Monitoring the Mcirinc Environment

of Long Island Sound
at Millstone Nucleeir Power Station

Watcrford, Connecticut

Niantic
Bay

Twotree
Channel

SUMMARY OF STUDIES PRIOR
TO UNIT 3 OPERATION

HORTMEASV imLrillsS

m

THE CONNECTICUT LIGHT AND POWER COMPANY
WESTERN MASSACHUSEHS ELECTRIC COMPANY
HOLYOKE WATER POWER COMPANY
NORTHEAST UTILITIES SERVICE COMPANY
NORTHEAST NUCLEAR ENERGY COMPANY

ENVIRONMENTAL LAB

April 1987

mi

Contents

SUMMARY 1

ROCKY INTERTIDAL STUDIES 1

BENTHIC INFAUNA 3

LOBSTER POPULATION DYNAMICS 6

EXPOSURE PANEL PROGRAM 8

FISH ECOLOGY 9

WINTER FLOUNDER STUDIES 11

ACKNOWLEDGEMENTS 15

SUMMARY

The Millstone Nuclear Power Station (MNPS) is located on the north shore of Lxing Island Sound
(LIS) in Waterford, Connecticut. The station consists of three operating units: Millstone Unit 1
commenced commercial operation in 1970, Unit 2 in 1975 and Unit 3 in 1986.

Extensive studies of the potential impacts of MNPS on local marine flora and fauna have been
conducted since 1968. During this period studies have consistently been reviewed and updated to assure
that the best available methods were used. This report summarizes data from all monitoring programs
performed at MNPS during 2-unit operation and is intended to provide information which will establish
the baseline for all impact assessment studies during 3-unit operating conditions.

ROCKY INTERTIDAL STUDIES

Attached plant and animal species on local rocky shores were identified, temporal and spatial
patterns of occurrence and abundance of these benthic species were examined, and physical and biological
factors that induce variability were identified. Qualitative algal collections, quantitative studies of intertidal
organisms, recolonization studies, and Ascophyllum nodosum studies were performed to assess impact
and are summarized below.

ITie local flora, as characterized by qualitative algal collections, has shown consistent spatial and
temporal patterns of distribution during Unit 1 and 2 operation. Overall, 158 algal species have been
identified since the inception of the monitoring program in 1979, consisting of 73 reds, 40 browns, and
45 greens. Several of these species were site-specific, and others were seasonally important. The greatest
number of algal species recorded from a single collection usually occurred in spring-eady summer for
all stations. The most species collected in any month was 117 in July and the fewest (101) in March.
The most species collected at any station was 131 at Bay Point and the least was 109 at both Seaside
Exposed and Twotree Island. Yearly, the greatest species number generally occurred at White Point.

The proportions of reds, browns, and greens are similar throughout the area and independent of
species number when analyzed by month and station. Annual percentages of species in each division

(1979-1985) ranged from 44-47% for reds, browns 25-27%, and greens 26-30%. The divisional propor-
tions vary seasonally: reds are more prevalent in August- December, browns in February-May, and
greens in May-July. When represented as percent occurrence of reds, browns, and greens (46:25:29), the
local flora is consistent with those reported by other researchers in the northwest Atlantic.

Quantitative studies show intertidal zonation patterns typical of rocky shores throughout New
England, with the high intertidal dominated by barnacles, the mid intertidal by barnacles and fucoids,
and the low intertidal dominated by Chondrus crispus, a perennial red alga. The abundances of these
major components of local rocky shore communities vary over time and space. Variations are predictable
and explainable in terms of seasonality, degree of exposure, intertidal height, inter- and intraspecific
competition, and life-history of the organisms. Changes to communities have been minor, indicating
stable environmental conditions during 2-unit operation.

An exception to the local stability is the development of a community dominated by opportunistic
ephemeral algae after the opening of the second quarry cut in August 1983 at Fox Island -Exposed (FE),
the station closest to the discharges. This change was attributed to thermal incursion and water
temperatures in excess of 28 °C. High water temperatures in late summer 1984 were responsible for
the elimination of the perennial algae Chondrus crispus, Fucus vesiculosus and Ascophyllum nodosum from
the low intertidal at FE. Codium fragile, a large green alga, became and remains the dominant component
of the FE community. It is expected that the present FE community will continue to be dominated
by opportunistic, warm water-tolerant algae.

Millstone Point, the second-closest station to the discharges, has shown a decrease in Fuct/s
vesiculosus coverage since 1981 when monitoring first began there. In addition, an increase in grazers,
especially Ijtlorina liltorea, has been observed since the second cut was opened.

Rccolonization studies, employing transects and exclusion cages, allowed isolation and identification
of some factors that infiuence the structure of local rocky intertidal communities. Rccolonization was
influenced by time of year in which denuding occurred, and related to degree of exposure and intertidal
height, e.g., rapid in the high intertidal of an exposed station and slow in the low intertidal of a sheltered
station. Results from the exclusion cage studies have shown that rates and patterns of rccolonization,
both with and without the influence of grazers and predators, were unaffected by proximity to the discharge.

Growth and mortality studies of Ascophyllum nodosum, a perennial brown alga sensitive to water
temperature change, were included in the rocky intertidal sampling program. Tip length analyses helped
distinguish between a stressed population at Fox Island and populations at two reference stations. Since
1979, Ascophyllum plant loss averaged about 60% and tip loss about 80% overall; there was much
variability in plant and tip mortality from year to year.

With the exception of the FE intertidal community, no significant changes to the benthic shore
biota were observed that could be attributed to MNPS operation.

BENTHIC INFAUNA

Infaunal communities in the vicinity of MNPS were sampled to provide data needed to characterize
suhtidal and intertidal community abundance and species composition, identify spatial and temporal
changes in these parameters and evaluate whether any observed changes were the result of construction
and/or operation of MNPS.

Intertidal

Sediments at the three intertidal sampling stations were composed of medium sands that usually
contained low amounts ( < 3%) of silt/clay. During the baseline period, sediment grain size and the
percentage of silt/clay were more consistent at stations exposed to constant wave-induced scour while
at the seasonally protected .Jordan Cove beach, these parameters exhibited considerable variability.

At all stations, infaunal communities were dominated by polychaetes and oligochaetes; these groups
often accounted for over 75% of the total number of individuals collected annually. The polychaetes,
Scolecokpides viridis, and Polydora ligni, and the oligochaetc group were among the dominants at all
stations. At .Jordan Cove, oligochaetes accounted for over 60% of all individuals in 5 of the past 6
years and was the most abundant taxon in each of the last six sampling years. At Giants Neck and
White Point, rhynchocoels, Paraonis fulgens, and Haploscoloplos fragilis were dominant, contributing
over 10 percent of the total individuals over years.

Quarterly mean abundance (no./core) at intertidal stations ranged from 4 to 840 and mean species
numbers from < 1 to 13. Overall, species abundances and species numbers were highest at Jordan
Cove and of similar magnitude at Giants Neck and White Point. In general, intertidal abundance and
species number were higher during warmer sampling periods (June and September) than during colder
ones (March or December). Multiple regression analyses, which were based on natural abiotic variables
were used to identify and remove naturally-induced temporal variations in abundance and number of
species. After adjusting for this variation, no significant increasing or decreasing trends in abundance or
species number were evident from 1980 to 1985.

Annual mean species diversity (H') over the study period ranged from 1.2 to 2.3, and evenness (J)
from 0.4 to 0.7, and on an annual basis, no consistent spatial or temporal shifts in IV have occurred
over the monitoring period. Diversity parameters reflected the spatial differences evident in the structure
of intertidal communities throughout the monitoring program.

l')ata collected during the baseline period characterized the spatial relationships among sampling
stations and investigated the extent and direction of temporal fluctuations in the abundance and numbers
of species that have occurred from 1980 - 1985. During this period, no changes in intertidal communities
could be attributed to operation of Millstone Units 1 and 2 or construction of Unit 3. Data presented
here appear representative of natural, undisturbed intertidal communities and will be the basis for all
future impact studies performed during 3-umt operating conditions.

Subtidal

Sediments at subtidal stations ranged from fme to coarse sands and contained up to 40% silt/clay.
Sedimentary characteristics of all stations, except Jordan Cove, have exhibited some temporal shifts
during the study. Values for grain size at Giants Neck have generally increased since 1982. At Intake,
smaller grain size and more highly variable silt/clay values have been observed since June 1983, when
construction activities (dredging and coffer dam removal) resulted in the deposition of fme material at
this station. Silt/clay content at Effluent has also become more variable following construction activities
in the area of the Unit 3 discharge cut.

Polychaetes and oligochaetes were the most abundant organisms at Effluent, Giants Neck and
Jordan Cove while arthropods were frequently abundant at Intake. Polychaete abundances were generally
highest in either September or June and although molluscs and arthropods contributed substantially to
the subtidal communities no consistent seasonal trends were seen in these groups.

During 1986, higher numbers of arthropod species were recorded in September and December
samples at Giants Neck and Jordan Cove than in previous years. At Intake, species numbers continued
to increase in 1986 continuing a trend begun in 1985 after construction activities (in 1984) eliminated
most of the species in this area. In contrast, the numbers of species and individuals of all the major
taxa at Effluent were generally lower in 1986 than in the previous two years.

From March 1 979 to March 1 986, mean quarterly abundance of subtidal communities ranged from
9 to 633 (no. /core) and mean species numbers (no. /core) from 5 to 46. Highest quarterly abundances
generally occurred in June or September at all stations. After removing naturally induced temporal
variation, no significant increasing nor decreasing trends in annual mean abundance were evident at any
subtidal station. Species numbers were generally highest in June or September at Effluent, Giants Neck
and .lordan Cove; (December at Intake). At Effluent, the mean species number has increased significantly
over the monitoring period.

Over all stations and years, oligochaetes (as a group) were the most consistently dominant taxon,
accounting for 4 to 61% of the total individuals collected. Other taxa among the more consistently
abundant forms were Pofycirrus eximius, Protodorvillea gaspeensis, Tharyx spp., Aricidea catherinae, and
Tharyx aculus. Of all communities, Intake was the most dissimilar; At this station, 29% of top ten
dominants were species of amphipods. In addition, other dominant taxa at this station exhibited strong
temporal fluctuations in abundance.

Mean annual species diversity (IT) ranged from 2.6 to 4.6 with lower values generally reflecting
short-term pulses in species abundances. High H' values reflected changes in the numbers of individuals
or species, but not in the equality of the distribution of individuals among species.

The subtidal benthic infaunal program has provided data necessary to characterize communities
inhabiting areas potentially impacted by power plant operations (Intake, Effluent, and Jordan Cove) and

an unimpacted area (Giants Neck). During the baseline period, temporal and spatial changes in species
abundance and community composition were evident at all stations; however, those at Intake and
Effluent appeared power plant related. Observed changes occurred prior to 1985, and were due to Unit
3 construction activities, including dredging, and not to operation of Millstone Units 1 and 2. The
opening of the second discharge cut may have caused recent changes in sedimentary and community
parameters observed at Effluent. The widespread nature of infaunal community changes at Giants Neck
and Jordan Cove were limited mostly to rearrangements in the ranking of traditionally dominant species
which suggest a response to naturally occurring events and are not related to operation or construction
of the Millstone facility.

LOBSTER POPULATION DYNAMICS

The lobster population in the Millstone Point area was sampled using pots from 1976 to 1985.
I/obsters > 55 mm carapace length were tagged and released to monitor growth and movement. Sex,
presence of eggs, carapace length, missing claws and molt stage were also recorded. Tagged lobsters
were released at the site of capture. These studies characterized population dynamics of the local lobster
stock during two unit operation. In addition, studies of lobsters caught on the intake traveling screens,
(impingement) and larvae drawn through the plants cooling water system, (entrainment) were conducted
to assess these impacts of Millstone Units 1 and 2 on the local lobster population.

Annual total catch per unit effort (CPUE) ranged from 0.56 to 2.10 lobsters per pot from 1976 to
1985. The lower CTUE values corresponded to data collected with wood pots which allow small
lobsters to escape between the 3-5 cm lath spacings. Wood and wire pots used during a 3 1/2 yr
gear-comparison study provided the basis for a decision to use all wire pots in our lobster studies
beginning in 1982. The CPUE of legal -sized lobsters (greater than or equal to 81 mm CL) was similar
for wood and wire pots throughout the gear comparison study. With the exception of 1981, total CPUE
was significantly higher for wire pots due to greater catches of sub-legal lobsters in wire pots. A special
study conducted during 1982 to investigate the lower catch of wire pots used in 1981 indicated that trap
efficiency was affected by the construction and placement of funnels used in pots. Other factors that
contributed to the efficiency of lobster pots were the number of days between pothauls (soaktime) and
the infiuence of competing species caught in pots. Mean monthly CPUE was adjusted accordingly using
covariance analysis to account for these influences. Dredging activities in the vicinity of the intake

structures were responsible for lower catches at the Intake station during 1985, however, after the dredged
area has stabilized lobsters will probably return to the area and catch rates at that station should increase
in 1986. Based on the annual mean CPUE and inspection of the confidence intervals around the mean,
the 1980 and 1981 CPUE's were the lowest annual values of all years from 1978 to 1985. Conversely,
the 1982 CPUE was the highest annual value due to a strong prerecruit class in 1982 which sustained
record landings throughout Long Island Sound during 1983 and 1984 when these lobsters molted to
legal size.

Size frequency distributions indicated that wire pots caught significantly more small lobsters ( < 75
mm) than did wood pots. Annual mean carapace lengths of lobsters caught in wire pots have been
consistent (range 70.8-71.8). Since 1975, the overall sex ratio of males to females was close to 1:1
however, when three stations were compared, Twotree (1.5 km offshore) had consistently higher pro-
portions of females, whereas Intake and Jordan Cove (<0.5 km offshore) had slightly more males.
Berried females comprised between 3.1 and 6.7% of all females caught from 1975 to 1985 and greater
proportions were caught at Twotree. The size distribution of berried females collected and the abdomen
width/carapace length relationship suggest that females first become sexually mature at about 50 mm
carapace length and that all females are mature at 95 mm carapace length.

The number of molting lobsters observed in the weekly catch varied from year to year and over
the sampling period. In general, molting peaked in June although in several years a fall molting peak
was also observed. The average growth per molt of males (14.1%) and females (13.7%) was significantly
different. The percentage of lobsters missing one or both claws (culls) ranged from 9.0 to 17.4%; more
lobsters caught in wood pots experienced claw loss (14.4%) than lobsters caught in wire pots (12.7%).
Since 1975, of the 57,359 lobsters caught; 47,259 were tagged and released, and 8,053 (17%) were
recaptured in our sampling program. Commercial lobstermen caught an additional 13,394 (28.3%) of
our tagged lobsters over the same period. About 95% of the lobsters were recaptured at the release
station; movement between stations was minimal. Of the movement that occurred, most was inshore
between Jordan Cove and Intake. Tagging studies indicate lobster movements are restricted to the local
area since 9 1 % of the commercial recaptures occurred within the study area; of those lobsters that were
recaptured outside the study area, most moved to the east. Some lobsters traveled considerable distances,
more than 100 km offshore, where they were caught on the edge of the continental shelf (Block and
Hudson canyons).

Ix)bster larvae entrainment studies indicated that lobster larvae are susceptible to cntrainment from
mid-May through late-June. The occurence of lobster larvae in the cooling waters coincided with the
peak abundance of berried females caught in our traps. More lobster larvae were collected in night
samples (substantiated by two 24 h samplings in 1985). The fact that more larvae were collected at
night when surface densities have been reported to be lowest may result from a combination of larval
behavior and the intake structure curtain wall design. This design minimizes entrainment of lobster
larvae during day when larvae are surface oriented. Survival of lobster larvae after passing through the
plant's cooling water system was observed indicating that entrainment mortality is lower than the assumed
100%.

Since 1975, an estimated 11,359 lobsters were caught on the intake traveling screens. The number
of lobsters impinged at Units 1 and 2 was highest in 1982, corresponding with the highest annual trap
catch, A fish return system (sluiceway) was constructed at Unit 1 and began operating in December
1983 which improved survival and minimized damage to lobsters associated with the impingement process
at MNPS.

There is no evidence to date that MNPS has significantly affected the local lobster population.
I'luctuations in the annual abundance of lobsters throughout Long Island Sound and the variability in
annual (.TUE's of the local lobster population appear to be related to natural events.

EXPOSURE PANEL PROGRAM

Patterns of abundance and distribution of fouling and woodboring organisms on exposure panels
at ambient water sites, determined during 2-unit operation, have been consistent from year to year, and
were predictable based on seasonal water temperatures, and the life stages available for settlement.
Wood-loss was caused primarily by Teredo nax'alis, and was highest during the May-Nov exposure
period. Variation in identity and abundance of species that colonized the panel surfaces did not appear
to affect recruitment or abundance of woodborers.

Effluent was also characterized by the absence of cold water species, e.g., Laminaria sacc.harina, and by
the presence of a warm water shipworm, Teredo barlschi.

Teredo hartschi also maintained a reproductive population in panels located 100 m outside the
quarry, exposed to the effluent produced by 2-unit operation. Exposure to elevated temperatures may
be required for larval settlement. Teredo navalis, the native shipworm, was also found in the MNPS
thermal effluent; there was a trend of increasing abundance with decreasing distance from the quarry.

Results from the Timber Study show that untreated wood is rapidly degraded in local waters,
primarily by Teredo navalis; Red Oak is more resistcnl than Douglas Fir, but blocks with a minimum
dimension of 6.4 cm have a survival time on the order of 2-3 yrs.

Chemical treatment can deter woodborer attack, but if timbers are cut after treatment, unprotected
surfaces are exposed, and are susceptible to woodborers. This susceptibility is less for creosote treated
wood than for CCA treated wood, as creosote is a better penetrant.

Characteristics of fouling and woodboring communities in the vicinity of MNPS have been estab-
lished during 2-unit operation. Comparisons of community and population parameters determined after
Unit 3 is operational will permit assessment of the potential added impact.

FISH ECOLOGY

The construction and operation of MNPS could affect fish assemblages in several ways. Lxirger
fish may be removed from the population by impingement on the intake screens; eggs, larvae and small
fish may be removed during entrainment through the cooling water system; and spatial distribution of
local fish populations may change in response to the cooling water effluent.

Several programs were established to provide baseline data for assessing impacts of MNPS on fish
assemblages. Ihese include studies of planktonic, demersal, pelagic and shore-zone fish assemblages, and
estimates of the number offish impinged and entrained. Plankton studies conducted since 197.3 included
collections of fish larvae at various stations, and entrainment mortality and thermal tolerance research
on selected larval fish taxa. The trawl sampling program was established in 1973 to monitor spatial

Several programs were established to provide baseline data for assessing impacts of MNPS on fish
assemblages. These include studies of planktonic, demersal, pelagic and shore-zone fish assemblages, and
estimates of the number offish impinged and entrained. Plankton studies conducted since 1973 included
collections of fish larvae at various stations, and entrainment mortality and thermal tolerance research
on selected larval fish taxa. The trawl sampling program was established in 1973 to monitor spatial
and temporal fluctuations of demersal fish. The gill net program, started in 1971 to provide qualitative
estimates of local pelagic fish assemblages, was dropped at the end of 1982 because catches were generally
low and none of the species collected were adversely affected by MNPS. The seine sampling program
was established in 1969 to monitor shore-zone fish. Impingement monitoring began at MNPS Unit 1
in 1972 and at Unit 2 in September 1975 and was supplemented by several fish diversion and survival
studies. These programs, which provide the data necessary for assessing the effects of two-unit operation
also provide the baseline for three-unit impact assessment.

Over 100 taxa of fish have been collected in the various Fish Ecology monitoring programs at
MNPS from .January 1976 through December 1985. Composition of the fish assemblages studied during
that period remained relatively stable and were typical of those reported for LIS by other researchers.
Eight taxa were selected for detailed analyses based on their susceptibility to impact from impingement
and entrainment: anchovies, sand lance, sticklebacks, silversides, tomcod, grubby, cunner and tautog.

The abundance of these taxa varied both seasonally and annually in all programs and to separate
fluctuations representing natural variability from those resulting from the construction and operation of
MNPS, a time-series approach was developed and applied to the monitoring data. This approach, which
combined several statistical techniques (harmonic regression, analysis of variance and time-series analysis)
to summarize catch fluctuations in the long-term data series, provided confidence intervals that were
narrower than those associated with annual or monthly means or medians and was, therefore, more
sensitive to unusual abundance fluctuations.

The abundances of potentially impacted taxa remained relatively stable throughout the 10-year
period, except for larval and juvenile sand lance, and larval anchovy, cunner and tautog. Except for
larval sand lance, these abundance changes were short-term. Larval sand lance abundance decreased
during 1982 and has remained low since then. A mass impingement (390,000) of sand lance juveniles
occurred in a one week period in .luly 1984 but was an uncommon event and is not expected to recur.

10

In 1984, there was a marked decrease in the abundance of larval anchovy, cunner and tautog but this
decrease was also observed in other parts of LIS. The reasons for this decline were not known but
during this time ctenophores, a plankton predator, were abnormally abundant.

Impacts from the construction and operation of MNPS were assessed using representative collections
of fish assemblages during the operation of Units 1 and 2. Except for larval sand lance, there was no
indication that catches of the most abundant fish taxa were consistantly below historic levels and for
sand lance, the observed fluctuation occurred along the entire Atlantic coast. Thus the operation of two
nuclear power plants at MNPS has not adversely affected fish abundance, distribution or species
composition in the Millstone area of LIS.

WINTER FLOUNDER STUDIES

The life history and population dynamics of the winter flounder (Pseudopleuronectes americanus)
have been studied intensively since 197.1, due to its importance to the sport and commercial fisheries of
Connecticut and potential for impact. Because winter flounder stocks are localized, most work has
concentrated on the population spawning in the Niantic River to determine if MNPS impacts of
impingement and entrainment have caused or would cause changes in abundance beyond those expected
from natural variation.

Annual estimates of the Niantic River spawning population have been made since 1976. An
abundance index based on the stochastic model of Jolly for open populations showed that numbers
were relatively stable from 1976 through 1980, increased to a peak in 1982, and subsequently declined
to an 11-yr low in 1986. Abundance determined by trawl CPUE generally paralleled the Jolly index
through 1982. The decline in CPUE was greater through 1985 and less in 1986 than for the corresponding
.lolly estimates. The influence of potential biases on both estimators were examined. A third measure
of abundance was provided from trawl monitoring program data using time-based harmonic regression
models. However, models from most stations were unsatisfactory due to insufficient data or a lack of
a repetitive pattern of abundance. High variability in catch, relatively low effort, and the mixture of
stocks found at most stations at certain times of the year make these trawl data difficult to interpret
and of limited use in assessing MNPS impact on the winter flounder. Throughout southern New

England, winter flounder abundance has declined in recent years because of natural fluctuations and also
most likely because of recent increases in commercial fishing.

As reported for other populations, the average sex ratio for Niantic River winter flounder was 1.44
in favor of females. The length of 50% maturation of females was 26.8 cm, equivalent to age 3 or 4.
Most spawning in the Niantic River was completed by early April with annual variations apparently
related to water temperature. Egg production was a function of female size and the length-fecundity
relationship was similar to those reported for other populations. Egg production peaked in 1982 and
has since decreased about 80%.

Scales were successfully used to age winter flounder. Mean lengths of age 3 and older females
were significantly larger than those of males. Growth was relatively rapid in early years, but older age
groups overlapped considerably in size. Growth of the Niantic River fish was less than other populations
in the region through age 2, but equaled or exceeded their means at age 3 and older. The von BertalanfTy
model was used to calculate population growth parameters using 1983 length-at-age data. Loo was
determined as 423 and 381 mm and K as 0.42 and 0.44 for females and males, respectively. The mean
annual survival rate of age 3 and older adults was determined as 0.486 using a catch curve with samples
combined from successive years to reduce bias. As found elsewhere, the winter flounder preyed upon
a variety of benthic organisms and algae. Food items varied by location and reflected bottom type and
different benthic communities.

The overall rate of return of Petersen disc-tagged winter flounder was 25%. About twice as many
were taken by the sport than the commercial fishery, although less cooperation was probably received
from the latter. Most (70%) of the returns were from local waters and three times as many of the
longer-distance recaptures were made in waters to the east than to the west.

Direct tissue isoelectric focusing techniques were used to differentiate stocks of winter flounder.
Good separation was achieved using fish from major estuaries in Connecticut and Rhode Island at least
8 km apart. A second study using fish from areas closer to MNPS showed more homogeneity, with
significant intermixing occurring throughout much of the year. The technique could not be used to
separate immature specimens.

Several special studies and analyses were conducted to identify possible sampling biases in the larval
winter flounder data base. The results of these studies included reduced larval net extrusion with 202-fim
mesh nets compared to 333- and 505-jim nets, increased sample density of larger larvae in night
collections, and changes in sample densities in relation to tidal stage at a station in the lower portion
of the Niantic River. Due to the identified sample biases, much of the offshore data collected prior to
1980 could not be used to examine the life history of larval winter flounder.

Based on the abundance and distribution of smaller larvae, spawning primarily occurred in the
Niantic River. larvae were gradually flushed into Niantic Bay, where larger larvae dominated. The
spatial distribution of larvae within the Niantic River varied from year to year, but generally smaller
larvae were more prevalent in the upper portion of the river and larger larvae in the lower. The lion's
mane jellyfish was identified as an important predator of larval winter flounder.

Eight tidal export-import studies were conducted at the mouth of the Niantic River during 1983-85.
The results showed a net export of 4 mm and smaller winter flounder larvae and a net import of 5 mm
and larger larvae. Larvae with developed fin rays migrated vertically in response to tidal currents to
reenter the Niantic River and those within the river demonstrated a similar behavior as a retention
mechanism.

Examination of otoliths from field-collected and laboratory-reared winter flounder larvae indicated
that daily increments were not visible. Based on the length-frequency distribution, most larval mortality
occurred at the time of first feeding (3-4 mm). Transition to the demersal juvenile stage occurred at
about 6-7 mm.

Abundance of post-larval young-of-the-year peaked in mid-June and stabilized by late July. Young
were most numerous in the lower river during 1983, with similar densities found during 1984 and 1985.
Growth of young in the lower river was significantly greater than at stations farther upriver after
mid-June. Weekly mean lengths in 1983 were about 6 to 8 mm larger than in 1984 or 1985. Monthly
survival estimates of young ranged from 0.552 to 0.569 in the lower river and 0.661 at a station in mid-river.

Peak abundance of age 1 juvenile winter flounder taken in the Niantic River during the adult
surveys occurred in 1981, with second and third highest CPUE in following years. An 11 -yr low was

13

found in 1986. However, in recent years juveniles have been found in more areas throughout the river
and in Niantic Bay during the time of the surveys. This variation in distribution makes the estimation
of juvenile abundance less certain than that of adults.

About two -thirds of the total number of winter flounder impinged on the traveling screens of
MNPS were taken in winter. Before 1984, annual estimates usually ranged from 4 to 10 thousand with
winter storms accounting for large proportions of most annual totals. Sex ratios and reproductive
condition of impinged fish differed from fish taken in the river. The predominance of males and of
gravid females in the collections indicated that at times impingement was related to behavior of winter
flounder. A fish return sluiceway was installed at MNPS Unit 1 in December of 1983 and studies
showed that survival of returned winter flounder would be considerable (ca. 80-90%). This greatly
reduces the impact of impingement on the winter flounder.

Entrainment sampling has been conducted since 1976. A majority (>60%) of the winter flounder
larvae entrained were 5 mm and larger. The greatest entrainment densities occurred from mid-April
through May. Based on the median aimual entraiimient density, three years were low (1977-79), four
years were high (1976, 1980-83), and the remaining years were intermediate. Annual entrainment was
related to total egg production in the Niantic River and the length of time a larva was susceptible to
entrainment was related to water temperature. The effects of entrainment on larval winter flounder were
examined in the laboratory and field. Larvae 5 mm and larger were able to survive a AT of 13 °C for
up to 9 h. The estimated critical thermal maximum was approximately 24 °C. A mortality study
showed that about 80% of the Stage 4 larvae would have survived entrainment.

Impact assessment was addressed using a deterministic model developed by the University of Rhode
Island. The model, subdivided into hydrodynamic, concentration, and population submodels, predicted
a 5 to 6% decrease in the Niantic River population after 35 yr of MNPS operation. Based on the
initial assumptions, the model results were probably conservative. A new stochastic population dynamics
model, which takes into account the natural variability in the recruitment process, is currently under
development at NUEL and will provide a more realistic estimate of potential losses.

To date, there is no evidence that MNPS has significantly affected the local winter flounder
population. Variability in annual abundance appears to be related to natural events and has been noted

14

throughout the region. Future work at NUEL will focus on early life history stages and will include
estimates of larval mortality, which are critical to the assessment of MNPS impact.

15

ACKNOWLEDGEMENTS

The following report was prepared by the Environmental Laboratory staff (NUEL) of Northeast
Utilities Service Company. All contributors to this report are acknowledged below according to their
respective disciplines.

Laboratory Manager
Secretarial Support
Benthic Ecology

Eish Ecology

Statistical Support

Paul Jacobson

Dian Audoin

Robin Field
Bette Eields
James Foertch
Raymond Heller
Dr. Milan Keser

Dr. Linda Bireley
John Castleman
David Colby
Donald Danila
Greg Decker

Dr. Ernest Lorda

Donald Landers
Richard Larsen
Douglas Morgan
John Swenarton
Joseph Vozarik

David Dodge
• Christine Gauthier
Dorothy Hagen
JoAnne Konefal
Dale Miller

NUEL Mailing Address

Northeast Utilities Environmental Lab.

P.O. Box 128

Waterford, Connecticut 06385

Special thanks are extended to Dr. William Renfro, Director Environmental Programs Department
(NUSCo) and the following members of the Millstone Ecological Advisory Committee for their critical
review of this report.

16

Dr. Nelson Marshall University of Rhode Island (Emeritus)

Dr. William Pearcy Oregon State University

Dr. Saul Saila University of Rhode Island

Dr. John Tietjen City College of New York

Dr. Robert Wilce (University of Massachusetts) and Dr. Robert Whitlatch (University of Connecticut)
are gratefully acknowledged for verifying species identifications and for providing critical reviews of early
drafts of this report. Special thanks also to personnel at the Connecticut Department of Environmental
Protection, Marine Fisheries Bureau, particularly Eric Smith, Penny Ilowell, and Mark Blake for
providing data and other information used in preparing this report.

17

Contents

INTRODUCTION 1

BIBMOGRAPHY 9

INTRODUCTION

The Millstone Nuclear Power Station (MNPS) is located on the north shore of Long Island Sound
(L,IS) in Waterford, Connecticut. The station consists of three units located on a peninsula bounded by
Jordan Cove on the east and by Niantic Bay on the west (Fig. 1). Millstone Unit 1, which commenced
commercial operation November 29, 1970 is a 652-MWe boiling water reactor (BWR). Unit 2, an
870-MWe pressurized water reactor (PWR), began operating October 17, 1975. Construction of Unit 3,
a 1,150-MWe PWR, began in August 1974; commercial operation began April 23, 1986.

Niantic Boy
Figure 1 . Site plan of the Millstone Nuclear Power Station.

All three units use once-through condenser cooling water systems. The rated circulating flows for
Units 1, 2 and 3 are 935, 1,220 and 2,000 cfs, respectively. Cooling water is drawn from depths greater
than four feet below mean sea level by separate shoreline intakes located on Niantic Bay. The intake
stRictures, typical of shoreline installations, have course bar racks and traveling screens. The cooling water,
heated to 17 "C above ambient, flows from discharge structures through an abandoned granite quarry and
exits into LIS through two channels equipped with fish barriers. Cooling water flow rates from 1976
througli 1985 are presented in Figure 2 for Units 1 and 2. Flow rates for Units 1 and 2 prior to 1976 are
provided in Appendices on file at Northeast Utilities Fnvironmental Laboratory (NULL). Ambient water
temperatures and AT for the same period are presented in Figure 3.

250
D ;o 200

i]

t 0 150
0 E

II

100

UKJi ItXn Mm JAK79 JiWaO JAIISl JWS2 JMH3 JANM JMa5 JANM

Time

Figure 2. Cooling water flow rates for Units 1 and 2 from 1976 to 1985

M16 mm jakts mn imo jamii imi imi janm jtMi janss
Time

JW76 JAN77 Mtn JAN73 JANSO JAM1 JANU JMIU JiWM JANS5 MSS

Time

Figure 3. Ambient water temperature and AT during two unit operations (1976-85).

The potential impact of MNPS on LIS biota has been the focus of study since 1968. The early
biological investigations included exposure panel monitoring of woodboring and fouling communities, and
surveys of the intertidal sand, rocky shore and shore-zone fish communities. The program scope increased
considerably between 1970 and 1973 with the addition of heavy metal analyses of seawater and mollusc
tissue, studies of impingement, pelagic and demersal fishes, plankton, subtidal benthos, and lobster and
Niantic River winter flounder population studies (Battelle - W.F. Clapp Laboratories 1975; NUSCo 1975).
A bibliography of all Millstone-related studies is provided at the end of this introduction; results of these
studies are on file at NULL.

Studies of entrained plankton began in 1970 when Unit 1 became operational (Carpenter 1975); studies
at Unit 2 began in 1975. To date, the routine monitoring and special investigations have covered nearly
all components of the plankton, including ichthyoplankton, phyto plankton, and zooplai\kton. Effects of
chlorination and increased temperature on entrained phytoplankton were addressed and latent mortality
of 7,ooplankton after condenser passage was determined (Carpenter et al. 1972b, 1974b) L^ter, emphasis
was placed on entrained ichthyoplankton and the relative impact of entrainment on fish populations in
surrounding waters (NUSCo 1976b, 1984a).

Impingement monitoring began at Unit 1 in 1971 and at Unit 2 in 1975. The scope has varied from
a complete census of all impinged organisms (1972-1976) to the current program of counting those
organisms impinged during a 24 h period on several days per week. Special studies have evaluated the
effectiveness of several fish deterrent systems at the intakes, including acoustics, underwater lighting and a
surface and bottom barrier (NUSCo 1976b, 1980a, 1981a). In December 1983, a fish return system
(sluiceway) began operating at Unit 1 reducing impingement related impacts on fish and shellfish populations
(NUSCo 1981b, 1986b).

The potential effect of three-unit operation on selected species was also considered. Mathematical
population dynamics models were developed for the Niantic River winter flounder population (Hess et al.
1975, Saila 1976) and for the regional menhaden population (NUSCo 1976b, 1983c). These models
estimated the effect of predicted entrainment and impingement losses to populations over the life of the
power station.

Several hydrographic and hydrothermal studies have been conducted since 1965 (NUSCo 1983c).
These studies were of two types. Some were designed to predict the shape and extent of the plume under
1-, 2-, and 3-unit operations. Others were field studies designed to determine the general hydrographic
nature of the waters surrounding MNPS or to verify the shape and extent of the thermal plumes (NUSCo
1979d). In addition, a tidal circulation model was developed that predicted current patterns and thermal
distributions and simulated dispersal and entrainment of Niantic River winter flounder larvae (Hess et al.
1975; Saila 1976).

As a result of these studies, the hydrographic and ecological characteristics of surrounding waters are
described. Studies have been intensified and modified to provide the most representative data with respect
to the changing concerns and state-of-the-art techniques. The present report provides results of studies
conducted during two-unit operations and provides a basis for evaluating any long-term impacts associated
with three-unit operations at Millstone Point. The report also satisfies certain license and permit conditions
stipulated by the Connecticut Department of Environmental Protection and the Connecticut Power Facility
Evaluation Council.

All ecological and hydrographic studies through 1976 were conducted by consulting laboratories, most
notably Battelle - W.E. Clapp laboratories, Woods Hole Oceanographic Institute and Normandeau
Associates. In 1977, Northeast Utilities Service Company (NUSCo) began a phased, in-house takeover
beginning with the entrainment and impingement programs. Some benthic and lobster program respon-
sibilities were added in 1978. As of January 1980, all studies (excluding heavy metals) were being conducted
and reported by NL'SCo scientists based at NUEL. Critical scientific review is provided by a four-member.
Ecological Advisory Committee (see acknowledgements) that has provided continuing support since 1968.

Data from the MNPS monitoring programs, the results of which are presented in this summary report,
are stored on discs at NUEL and at Environmental Programs Dept. in Rocky Hill, CT. Appendices to
this report are also archived at NUEI,.

In addition to the monitoring programs described in this report, several studies were conducted in
earlier years but were later discontinued (i.e., phytoplankton, zooplankton, heavy metals). A brief summary
of these studies' results follows; more detailed results can be found on file at NUEL.

PHYTOPLANKTON - Phytoplankton, as primary producers, were considered to be an important
component of the marine ecosystem to study in early power plant impact assessments. Thus, various
studies were completed at MNPS from 1970 to 1982 to monitor and assess the impact of entrairunent on
phytoplankton community composition and abundance. The phytoplankton community in the vicinity
of Millstone was found to be similar to that of Long Island Sound and to that near Cape Cod (NUSCo
1983b). Carpenter (1975) found that the higher discharge temperature depressed productivity only during
warmer periods at Millstone. Chlorination had the greatest impact on phytoplankton, but during chlori-
nation the predicted 5-10% decrease in productivity and biomass Ln the effluent mixing zone at Millstone
could not be detected (Carpenter et al. 1974a). This result was not unexpected because NUSCo (1979a)
estimated that, assuming total mortality of entrained phytoplankton and using published growth rates, the
phytoplankton populations in the vicinity of MNPS could recover to preentrainment levels in 1 to 9 h.
Because it became apparent that power plant operation had a negligible impact on the phytoplankton
community, the phytoplankton program was discontinued in 1982 (NUSCo 1983a).

ZOOPLANKTON - Zooplankton densities in the Millstone area and potential entrainment losses
were also examined as part of the long term monitoring program because of the importance of zooplankton
to the marine ecosystem. Zooplankton studies were conducted from 1970 through 1983 and included,
estimates of zooplankton densities at several nearshore stations in and around Niantic Bay, estimates of
entrained zooplankton, and studies of entrainment-related zooplankton mortalities (NUSCo 1983a). Car-
penter et al. (1974b) found that entrainment resulted in zooplankton mortality but significant changes in
the zooplankton community near MNPS were not observed. Only a small percentage of the community
was directly influenced by power plant operation (4% of the average volume of the Niantic Bay tidal
exchange (NUSCo 1976b) and the densities and species composition were typical of greater LIS. Because
it was unlikely that detectable changes in zooplankton species composition or abundance would occur
during Unit 3 operation, the zooplankton monitoring programs were discontinued in 1983 (NUSCo 1983c).

OSPRFY - The osprey {Pandion haliaetus) is a pisciverous raptor found in many estuarine areas along
the east coast of North America. The area around MNPS is an established breeding ground for osprey;
both .fordan Cove and the Niantic River provide abundant food. Because the population in the northeast
declined during the 1950's and 1960's as a result of egg shell thinning from the ingestion of DDT, federal
officials placed the osprey on the list of threatened species. To assist the recovery of osprey populations
after the ban on DDT, NUSCo erected nesting platforms on MNPS property between 1967 and 1985

(NUSCo 1985a). Since then, 61 young have been produced from these nests; over 400 were produced in
Connecticut (NUSCo 1985a). NUSCo continues to monitor the recovery of these magnificent birds.

HEAVY METALS - Concentrations of heavy metals in seawatcr and shellfish tissue samples were
monitored five times per year from 1971 through 1983. Seawater and shellfish tissue samples were examined
for concentrations of copper, zinc, iron, chromium, and lead at areas adjacent to and distant from the
MNPS to assess possible heavy metal additions associated with seawater passage through the plant's
cooling water systems.

Results indicated enhanced levels of copper, nickel, and zinc in cooling water samples relative to levels
in seawater samples collected outside the immediate mixing zone of the MNPS plume (NUSCo 1983b).
However metal levels return to ambient at rates similar to the return of water temperature to ambient. Of
all shellfish tissue samples analyzed, only those from oysters inhabiting the quarry had elevated metal
concentrations. In general a decline in concentrations of soluble and insoluble phases of heavy metals was
observed and was related to improved analytical techniques rather than actual decreased levels in concen-
trations (Waslenchuk 1980, 1981, 1982, 1983). For example, concentrations in sea water reported in 1982
were significantly lower than reported in 1981, under similar plant operating conditions (NUSCo 1983b).
Since concentrations of metals found in shellfish outside of the effluent quarry were comparable during
one and two unit operations, and since Unit 3 has a titanium condenser that resists corrosion, the heavy
metals monitoring program was discontinued in 1984.

AQUAC^UITURE - In 1976, a study was initiated to assess the feasibility of utilizing the thermal
effluent in the culture of selected species of shellfish. The bay scallop {Argopectin irradians) was chosen
as the study species because it could be easily cultured in the laboratory and was a desired sport and
commercial species locally. Bay scallops were successfully reared from egg to juvenile stages utilizing
effluent waters at Millstone Point (MRI 1980). Discharge waters 11-12 °C above ambient temperatures
favored the conditioning of brood stocks for early spring and late fall spawnings. This, coupled with
increiu->cd growth rates of juveniles cultured in the effluent during winter months, potentially provided a
method of seeding coastal waters with juvenile shellfish. Initial experiments to seed hatchery reared juveniles
into nearby Jordan C^ove indicated that predation of young scallops was high and would be the limiting
factor in the success of any put-and-take type of fishery.

BIOASSAY - In 1981, continuous effluent toxicity testing of the discharge from MNPS began using
populations of sheepshead minnow {Cyprinodon variegatus) and mysid shrimp (Mysidopsis bahia) subjected
to undiluted effluent in quany waters and to Jordan Cove water (as a control), both adjusted to constant
temperature of about 20 "C. Both organisms have been extensively used in marine toxicity testing and
are among EPA recommended test organisms. Because the effluent is primarily condenser cooling water,
it has a low potential for toxicity. Potential toxicants that are present in the MNPS effluent include
chlorine, heavy metals and hydrazine.

Sheepshead minnow embryo-larval tests were used to assess acute toxicity of the discharge because
the early life history stages of fish are most sensitive to toxicants. Sheepshead minnow life cycle tests were
also conducted to assess chronic toxicity by examining egg viability, larval mortality and growth. Parameters
examined during Mysidopsis bahia toxicity testing were population growth rates, and reproductive potential.
Comparisons were made between animals maintained in undiluted MNPS effluent and Jordan Cove water.

Results of these studies to date indicate no chronic toxicity related to the MNPS effluent. No
differences were found between control and effluent treatments for egg viability, and development and
growth of larvae (NUSCo 1983f, 1986c). Effluent toxicity testing will continue during three unit operation.

SHELLFISH SURVEY - During 1984 and 1985, the abundance and distribution of edible bivalves,
hard clams {Mercenaria mercenaria), soft-shell clams {Mya arenaria), eastern oysters (Crassostrea virginica),
and bay scallops {Argopectin irradians) was documented. These surveys were conducted in three steps at
intertidal and subtidal areas around MNPS to establish a data base for these commercially valuable bivalves
prior to three unit operations and to verify the distribution of bivalves in Jordan Cove previously reported
in the State of Connecticut Shellfish Concentration Area Maps (NUSCo in prep.).

Survey results indicated that hard clams were the most abundant and valuable shellfish. In addition
to the target species assessed in these studies, the razor clam {Ensis directus) was collected and was the
second most abundant species, however, it is not a commercially or recreationally harvested species in the
Millstone Point area. Soft-shell clams occurred at lower densities and supported a marginal recreational
fishery in Jordan Cove. Only a single eastern oyster was found during the survey; no bay scallops were
found in the study area although an important scallop fishery occurs in the Niantic River (about 2 km
from MNPS).

F,F,I ,GR ASS - Zostera marina is an important component of estuarine systems because it stabilizes
sediments and provides habitat for many marine organisms. In the early 1970s two studies were sponsored
by NUSCo and conducted by the University of Connecticut to document eelgrass distribution in the
MNPS area (Klotz and Knight 1973; Knight and lawton 1974). In 1985, NUSCo conducted a more
extensive survey which included mapping the extent of eelgrass in .lordan Cove, estimating standing stock
and monitoring plant density, length and reproductive status. These studies were conducted to compare
results of earlier eelgrass distribution and provide a quantitative data base prior to three-unit operations
to assess possible impacts on eelgrass after Unit 3 start-up. Initial results of the NUSCo studies show
average eelgrass densities ranged from 18 to 39 plants/m and average blade length ranged from 144-681
mm. Standing stock estimates at .Jordan Cove averaged from 39.4 to 297.7 g/m and were highest in July.
Effects of the thermal plume on the Jordan Cove eelgrass stock have not been evident during two unit
operating conditions.

BIBLIOGRAPHY

Balser, J. P. 1981. Confidence interval estimation and tests for temporary outmigration in tag-recapture
studies. Ph.D. Thesis, Cornell University, Ithaca, NY. 205 pp.

Battelle-Columbus laboratories, W.F. Clapp Laboratory, Duxbury, MA. 1969. A monitoring program
on the ecology of the marine environment of the Millstone Point, Connecticut area. Annual report
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the Millstone Point, Connecticut, area, with special attention to key indicator organisms--pre-operational
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1975. A monitoring program on the ecology of the marine environment of the Millstone Point,

Ccnnecticut area. Annual report presented to Northeast Utilities Service Company.

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(Connecticut area. Annual report presented to Northeast Utilities Service Company.

1977a. Benthic Program Evaluation. Prepared by John Dickinson and presented at the Millstone

Ecological Advisory Committee Meeting, November 7-8, 1977.

1977b. A study to determine if trawling has an effect on the scallop population in the Niantic

River. Presented to Northeast Utilities Service Company.

1977c. A monitoring program on the ecology of the marine environment of the Millstone

Point, Connecticut area. Annual report presented to Northeast Utilities Service Company.

1978a. Investigations on the effects of sample size on estimates of community parameters for

suhtidal sand fauna. Presented to Northeast Utilities Service Company. 27 pp.

1978b. A monitoring program on the ecology of the marine environment of the Millstone

Point, Connecticut area. Annual report presented to Northeast Utilities Service Company.

1978c. Exposure panel variability study Millstone. A special report presented to Northeast

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1979. Exposure panel variability study Millstone. A special report presented to Northeast

Utilities Service Company. 9 pp.

Bechtcl Corporation. 1966. Diffusion patterns of the circulating water discharge effluent for the
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Bireley, I,. E. 1984. Multivariate analysis of species composition of shore-zone fish assemblages found
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. 1985. Time-series modeling: Applications to long-term finfish monitoring data. Ph.D. Thesis,

University of Rhode Island, Narragansett, RI. 181 pp.

. 1987. Application of intervention analysis to power plant monitoring data. Proceedings of 12th

SAS Users CJroup International, Eeb. 8-11, 1987, In press.

10

Braincon Corporation. 1974. Hydrographic surveys, August-September 1973 and February 1974.
Report to Northeast Utilities Service Company.

Brown, R.T., and S.F. Moore. 1977. An analysis of exposure panel data collected at Millstone Point,
Connecticut. MIT, Cambridge MA. Rep. No. MIT-F,L 77 015. 119 pp.

Carpenter, F. J. 1975. Integrated summary report to NUSCo on entrainment of marine organisms.
Woods Hole Oceanagraphic Institute. 35 pp.

, S..I. Anderson, and B.B. Peck. 1971a. First semi-annual report to Northeast Utilities Service

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waters of a nuclear power station and problems associated with their measurement. Fst. Coast. Mar.'
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station on Northeastern \x)n% Island Sound, USA. Mar. Biol. 24:49-55.

Cole, (jr. II., R.L. Copp, and D.C. Cooper. 1977. Fstimation of lobster population size at Millstone
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12

, N.W. Davis, and J. Wennemer. 1977. Abundance, diversity and stability in shore-zone fish

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Johnson, G., J. Foertch, M. Keser, and B.R. Johnson. 1983. Thermal backwash as a method of
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Knight, J.I,., and R.B. lawton. 1974. Report on the possible influence of thermal additions on the
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13

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14

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15

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. 1979d. Millstone Nuclear Power Station Units 1 and 2 thermal plume study. March 1979.

16

1979c. Millstone Point Units 1 and 2 hydrothermal survey report July 25 - August 2, 1977.

Submitted to the Nuclear Regulatory Commission, January 1979.

19803. Monitoring the marine environment of Ix)ng Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1979.

1980b. Proposed ecological studies. Millstone Nuclear Power Station, 1981. Letter to Con-

necticut Department of Environmental Protection.

1981a. Monitoring the marine environment of Long Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1980.

1981b. Feasibility of modifying the Millstone LInits 1 and 2 cooling water intake screen wash

system to improve the return of fish to Long Island Sound. 67 pp.

1981c. Proposed ecological studies. Millstone Nuclear Power Station, 1982. Letter to Connecticut

Department of Environmental Protection.

1982a. Monitoring the marine environment of Ix)ng Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1981.

. 1982b. Scope of work - Adult winter flounder program Niantic River - spring 1983. 15 pp.

. 1982c. Millstone Nuclear Power Station Unit 3. Interim environmental report, operating license

stage.

. 1982d. Proposed ecological studies, Millstone Nuclear F'ower Station, 1983. Letter to Connecticut

Department of Environmental Protection.

. 1983a. Monitoring the marine environment of Ix>ng Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1982.

17

. 1983h. Monitoring the marine environment of Long Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Resume 1968-1981.

. 1983c. Millstone Nuclear Power Station Unit 3 environmental report. Operating license stage.

Vol. 1-4.

. 1983d. Proposed ecological studies, Millstone Nuclear Power Station, 1984. Letter to Connecticut

Department of Environmental Protection.

1983e. Infaunal community studies in the area of the Millstone Unit 3 discharge. L Initial

sampling results. December 1982 - .June 1983.

. 1983f. Affluent toxicity testing at Millstone Nuclear Power Station using sheepshead minnow

{Cyprinodon variegatus) during 1981 and 1982.

, 1984a. Monitoring the marine environment of Ix)ng Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1983.

. 1984b. Infaunal sand communities inhabiting the discharge quarry at the Millstone Nuclear

Power Station.

i984c. Proposed ecological studies. Millstone Nuclear Power Station, 1985. Letter to Connecticut

Department of Hnvironmental Protection.

J985a. Monitoring the marine environment of I/Ong Island Sound at Millstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1984.

1985b. Proposed ecological studies. Millstone Nuclear Power Station, 1986. Letter to Con-

necticut Department of Environmental Protection.

1986a. Monitoring the marine environment of long Island Sound at MilKstone Nuclear Power

Station, Waterford, Connecticut. Annual report, 1985.

18

. 1986b. The effectiveness of the Millstone Unit 1 sluiceway in returning impinged organisms to

l,ong Island Sound. 18 pp.

. 1986c. Effluent toxicity testing at Millstone Nuclear Power Station 1983 through spring 1986.

. 1986d. Proposed ecological studies, Millstone Nuclear Power Station, 1987. I.xtter to Connecticut

Department of Environmental Protection.

. 1987. Ecological significance of community changes at Fox Island 34 pp.

. In preparation. Survey of bivalve molluscs in Jordan and Outer Jordan Coves, Waterford,

Connecticut.

Perra, P., and C. Steinmetz, Jr. 1980. Further documentation for rare fishes and a list of seventeen
fishes new to the marine waters of Long Island Sound, Connecticut. Pages 1-13 in P.M. Jacobson, ed.
Studies of the ichthyofauna of Connecticut. Storrs Agric. Exp. Sta. Bull. 457.

Pritchard-Carpenter, Consultants. 1967. Continuous discharge tracer study, Twotree Island Channel
and Niantic Bay, Ix)ng Island Sound. Report to Millstone Point Company.

. 1970, Tracer study of the circulating water system, MUlstone Point Unit Number One. Report

to Millstone Point Company.

Raytheon Marine Research laboratory. 1968. Millstone survey, August 29, 1968. Report to Millstone
Point Company.

. 1969. Millstone survey, March 20, 1969. Report to Millstone Point Company.

Saila, S.B. 1976. Effects of power plant entrainment of winter flounder populations near Millstone
Point, Connecticut. URI-NUSCo Rep. No. 5. 139 pp + 4 app.

19

Schenck, R., and S. Saila. 1982. Population identification by biochemical methods with special reference
to the winter flounder Pseudopleuronectes americanus in the vicinity of Millstone Point, Connecticut.
Final report to Northeast Utilities. 47 pp.

Schneider, C".W. 1981. The effect of elevated temperature and reactor shutdown on the benthic marine
flora of the Millstone thermal quarry, Connecticut. J. Therm. Biol. 6:1-6.

Sissenwine, M.B., K.W. Hess, and S.B. Saila. 1973. Semiannual report on a mathematical model for
evaluating the effect of power plant entrainment on populations near Millstone Point, Connecticut.
Report period April 1, 1973 through September 30, 1973. MES-NUSCo Rep. No. 1. 78 pp.

. 1974. Second semiannual report on evaluating the effect of power plant entrainment on

populations near Millstone Point, Connecticut. Report period October 1, 1973 through March 31,
1974. MES-NUSCo Rep. No. 2.

. 1975. Interim report on evaluating the effect of power plant entrainment on populations near

Millstone Point, Connecticut. Report period April 1, 1973 to December 31, 1974. MES-NUSCo Rep.
No. 3. 197 pp.

Stone and Webster Engineering Corporation. 1965. Study on thermal effects analysis for a 1,200 Mw
plant at the Millstone site. Submitted to Millstone Point Company.

Stoltzenbach, K. and E. Adams. 1979. Thermal plume modeling at the Millstone Nuclear Power
Station. Report to Northeast Utilities Service Company.

Thomas, .I.M., .I.A. Mahaffey, K.L. Gore, and D.G. Watson. 1978. Statistical methods used to assess
biological impact at nuclear power plants. .1. Envir. Man. 7:269-290.

■['I (Texas Instruments, Inc.). 1977. Airborne thermal infrared survey, Millstone Point Nuclear Power
Station. Report to Northeast Utilities Service Company.

20

United States Atomic Energy Commission (USAEC). 1973. Final environmental statement related to
the continuation of construction of Unit 2 and the operation of Units 1 and 2. Millstone Nuclear Power
Station - Millstone Point Company. Docket Nos. 50-245 and 50-336. June 1973.

. 1973. Final environmental statement related to the proposed construction of Millstone Nuclear

Power Station Unit 3 - Millstone Point Company, et al. Docket Nos. 50-423. February 1974.

United States Nuclear Regulatory Commission (USNRC). 1984. Final environmental statement related
to the operation of Millstone Nuclear Power Station Unit No. 3. Docket No. 50-423. Northeast Nuclear
Energy Company, et al. December 1984.

Vaughan, D.S., N. Buske, and S.B. Saila. 1976. Interim report on evaluating the effect of power plant
cntrainment on populations near Millstone Point, Connecticut. Report period January 1, 1975 to
February 15, 1976. MES-NUSCo Rep. No. 4. 78 pp.

VAST, Inc. 1*571, June 1971 Millstone Point temperature survey. Report to Millstone Point Company.

. 1972a. Dye diffusion survey. Millstone Point, Connecticut, September - November 1971.

Report to Millstone Point Company.

. 1972b. Thermal survey and dye study Millstone Point, Connecticut, September - November

1971, Report to Millstone Point Company.

, 1972c. Study of an offshore thermal diffuser outfall by dye simulation (Phase III - 1978 unit).

Report to Millstone Point Company.

1972d. Thermal survey, Millstone Point Company, Unit No. 1, March- April 1972. Report to

Millstone Point Company.

Waslenchuk, D.G. 1980. The concentration, reactivity, and fate of copper, nickel, and zinc in a cooling
water plume. Final report to Northeast Utilities Service Company, January 27, 1980.

21

. 1981. The concentration, reactivity, and fate of copper, nickel, and zinc in a cooling water

plume. Final report to Northeast Utilities Service Company, October 23, 1981.

. 1982. The concentration, reactivity, and fate of copper, nickel, and zinc associated with a

cooling water plume in estuarine waters. Environmental Pollution (Chemistry and Physics, Series B),
.3:271-287.

. 1983. Tlie concentration, reactivity, and fate of copper, nickel, and zinc associated with a

cooling water plume in estuarine waters, II. The particulate phases. Environmental Pollution (Chemistry
and Physics, Series B), 5:59-70.

22

Contents

ROCKY INTERTIDAL STUDIES 1

INTRODUCTION 1

MATERIALS AND METHODS 2

RESULTS AND DISCUSSION 8

Temperature Data 8

Qualitative Studies 12

Quarry Study 20

Undisturbed Transects 22

Recolonization Studies 38

Transects 38

Exclusion cages 45

Ascophyllum nodosum Studies 50

(Jrowth 50

Mortality 51

SUMMARY 59

CONCLUSION 60

REEERENCES CITED 61

ROCKY INTERTIDAL STUDIES

INTRODUCTION

The intertidal zone and near-shore waters are among the most productive regions of the world (Mann
1973). Intertidal algae provide food directly and indirectly to snails, crabs, and other benthic invertebrates,
as well as to fish, shore birds, and man (Paine 1980; Edwards et al. 1982; Menge 1982). Some algae,
Ascophyflum nodosum for example, release a large portion of their annual biomass as detritus and dissolved
nutrients (.lossclyn and Mathieson 1978). Other algae, primarily annual species, are consumed directly.
I^rge perennial algae also contribute to the intertidal community's physical structure by providing shade
and protection to much of the shore biota, and attachment space for epiphytes (Lewis 1964; Stephenson
and Stephenson 1972; Menge 1975; Lobban et al. 1985).

CJradients of many parameters affecting shore populations result in universal patterns of zonation
(C^hapman 1946; I^wis 1964; Zaneveld 1969; Stephenson and Stephenson 1972). Some of these parameters
can be quantified and characterized over time, and some can be experimentally manipulated in an effort
to determine causal relationships (Connell 1961; Paine 1966; Dayton 1975; Menge 1975).

Rocky intertidal communities have certain attributes that make them ideal subjects for ecological
assessment (MYAPCo 1978; Wilce et al. 1978; IJLCo 1983; PSNII 1985). The stability of rocky shores
permits establishment of permanently marked sampling areas. A discrete segment of a community, in
many cases the same individual plants and animals, can be studied by successive observations. Some
shore species are long-lived, capable of integrating effects of environmental conditions over their life spans.
The presence of ephemeral species, which respond quickly to environmental conditions, reflects environ-
mental change or instability. Sessile and slow-moving species arc continuously exposed to potential
impacts; others arc motile, whose occurrence and abundance at a locality indicates the suitability of the
environment at a given time. Many intertidal species show precise seasonal patterns of occurrence,
abundance, and reproductive status. These seasonal patterns allow a multitude of spatial and temporal
biological comparisons (Vadas et al. 1978; Schneider 1981).

The interticial region in the vicinity of Millstone Point is exposed to a potential thermal impact from
MNPS. Response to an impact may be obvious or subtle, and may occur at a community, population,
or species level. The Rocky Shore monitoring program was designed and implemented with the following
objectives:

1. to identify the attached plant and animal species found on nearby rocky shores,

2. to identify and quantify temporal and spatial patterns of occurrence and abundance of benthic species
on these shores, and

3. to identify the physical and biological factors that induce variability in these intertidal areas.

To achieve these objectives, the rocky intertidal studies include qualitative algal collections, abundance
measurements of intertidal organisms (percent of substratum covered), measurement of rates and patterns
of recolonization following small-scale perturbation, experimental exclusion of grazers and predators for
selected areas, and growth studies of Ascophyllum nodosum. These studies permit determination of potential
biological perturbation from operation of Units 1 and 2 and construction of Unit 3. These studies also
provide base-line data that will pennit prediction and assessment of additional impact, if any, from
operation of Unit 3.

The purpose of this report is to provide a summary of results from all rocky shore studies performed
during 2-unit operation. Space limitations required considerable condensation of information; c<5mplete
data arc included in Appendix RS la-d.

MATERIALS AND METHODS

I'hc rocky intertidal sampling program at MNPS began in May 1968 (Fig. I; NU'SCo 1982); the
initial surveys were primarily qualitative in nature. In August 1978, the sampling program was evaluated,
and extensive modifications were proposed (Appendix RS II, Proposed ('hanges for Intertidal Rock
Sampling at Millstone Point). Modified sampling procedures were instituted in February 1979, incorporating
non-destructive sampling, emphasizing more frequent qualitative and quantitative collections. This report

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summarizes data collected from March 1979 through February 1986, and characterizes local rocky intertidal
communities under 2-unit operating conditions.

Qualitative Collections

Tlie benthic algal flora at nine rocky intertidal stations (Fig. 2) was monitored qualitatively on a
monthly basis. These stations are, in order of most exposed to least exposed: Bay Point (BP), Fox
Island-Exposed (FE), MiUstone Point (MP), Twotree Island [TT), White Point (WP), Seaside Exposed
(SE), Seaside Sheltered (SS), Giants Neck (GN), and Fox Island-Sheltered (FS). Sampling at MP and
TT began in October 19SI.

Figure 2. Loc.iLion of rocky inlcrlidal sampling sites. GN = GInnts Neck. BP=Day Point. MP= .Vliil.stone Point,
rn = Fox Isl.ind-C.xposcd. rS = Fox Island-Shcllcrcd. TT = Twotree Island. WP = White Point. SIZ = Sc.isidc
r.xposcd, .S.S = Sc.i.';idc Shcllcrcd.

Qualitative collections were made over an area sufficiently wide to characterize the flora at each site.
Samples were identified fresh, or after short-term freezing. Voucher specimens were preserved using various
methods, depending on the material: in 4% formaljn/seawater, as dried herbarium mounts, or on micro-
scope slides.

The Millstone quarry study was initiated in 1982. One site at the original quarry cut (site I, Fig. 3)
and three sites within the quarry (sites 2-4) were sampled monthly to permit examination of species
composition under greater than ambient water temperatures. The quarry samples were processed as
described for the qualitative collections from the rocky intertidal stations.

Figure 3. Detail map of MNPS vicinity. FL = original experimental Asrophyllvm site (1979-1984), FN = ncw
expcrimcnl.nl AsrnphvUum site (19S5-prcsent), 1-4 = effluent quarry collection sites.

Quantitative Studies

At each qualitative collection station except Twotrce Island (owing to insufficient exposed bedrock),
five permanent transects were established perpendicular to the water-line, one-half meter wide and extending
from Mean High Water to Mean I^w Water levels. Bach transect, composed of 0.5 x 0.5 m quadrats,
was non-destructively sampled monthly from March 1979 to February 1981, seven times per year from
March 1981 to April 1983, and six times per year, in odd numbered months since May 198.1 (see Appendix
RS MI, Fnvironmental Tech. Spec. Change Request for Intertidal Rocky Shore Survey). The percentage
of substratum cover of all organisms and remaining free space in each quadrat was subjectively determined
and recorded. Understory organisms, or species that were partially or totally obscured by the canopy
layer, were assigned a percentage that reflected their true abundance.

Recolonization Studies

Transects

Rates and patterns of recolonization following substratum denudation were determined in two series
of recolonization transect experiments that were conducted at four stations (Fox Island-F.xposed, Fox
Island-Sheltered, White Point, Giants Neck). Sample design included two pairs of stations with similar
degrees of exposure (Fig. 2): exposed at F'F, and WP, and sheltered at GN and FS. The Fox Island
stations, becau.se of their proximity to the MNPS discharge, were considered potentially impacted, while
White Point and Giants Neck were identified as reference stations. In April 1979, three vertical transects
were established at each station. Fach transect was scraped free of attached algae and invertebrates and
burned with a liquid petroleum gas torch. All recolonization transects were sampled monthly in the same
manner as described for undisturbed transects. The effect that seasonality of denuding had on recolonization
was determined in a second series of experiments that was established in September 1981, .10 months after
the initial denuding, when all recolonization strips were reburned.

Exclusion cages

Four series of exclusion cage studies at each of the four recolonization stations were undertaken to
determine the effects of grazing and predation on recolonization rates and patterns. The first series began
in April 1979; nine areas were selected at each station, three areas in each of three tide zones (high, mid,
and low tidal levels). In each area, two 20 x 20 cm patches were burned and cleared; one was covered
with a stainless steel mesh cage (20 x 20 x 5 cm, 3 mm mesh), the second left as a control. Each month
the percent cover of colonizing organisms was determined. The effect that season of denuding had on
rates and patterns of recolonization was determined, as with the recolonization transect experiments.
Subsequent series of exclusion cage experiments began in June 1980, September 1981, and December 1982;
each area was rebumed 15 months after the previous denuding.

The complete series of recolonization experiments (strip transects and exclusion cages) was completed
under two-unit operating conditions by March 1984, but the recolonization strips were monitored bimonthly
until March 1986 to assess long-term recovery. The observed degree of recolonization provides a base-line
against which to compare the impact of Unit 3 on rates and patterns of community recovery. The entire
series of experiments will be repeated under three-unit conditions.

Ascophyllum nodosum Studies

Growth and mortality of populations of the brown perennial alga, Ascophyllum nodosum, were studied
at two control stations (GN, 5.5 km west of the discharge and WP, 1.5 km east of the discharge, Fig. 2)
and an experimental station (FF, ca. 75 m east of the original Millstone quarry cut. Fig. 3) from 1979-1984
Ascophyllum was eliminated from FL in summer 1984, its loss attributed to elevated water temperatures
resulting from the thermal plume of two operating units discharging through two quarry cuts (NUSC'o
1985; also Appendix RS IV, Ecological Significance of Community Changes at Fox Island). In spring
1985 a second experimental Ascophyllum station (FN) was established between FE and I'S (Fig. 3; ca.
250 in from the quarry discharges, northeast of the Fox Island-Exposed sampling site).

Ascophyllum plants were measured at monthly intervals from April, after the onset of new vesicle
formation, until the following April. Fifty plants at each station were marked with a numbered plastic
tag at the base of each plant, and five apices were marked on each plant with colored cable ties (prior to

1985, with colored electrical tape on uncolored cable ties). Linear growth was determined by measurements
made from the top of the most recently formed vesicle to the apex of the developing axis, or apices if
branching had occurred. Vesicles had not developed sufficiently to be tagged in April or May, so five tips
were measured on each of 50 randomly chosen Ascophyllum plants. Monthly measurements of tagged
plants began in .lune. Lost tags were not replaced, and the pattern of loss was used as a measure of both
mortality and environmental stress. I^ss of the entire plant was assumed when the base tag and tip tags
were missing. Tip survival was determined in terms of remaining tip tags.

Temperature

Water temperatures were derived from the EDAN (Environmental Data Acquisition Network) system,
which continuously records a variety of environmental parameters and reports at 15-minute intervals.
Ambient water temperatures were recorded by sensors in Unit 1 and 2 intake bays, and effluent water
temperatures by sensors in the quarry cuts (Eig. 3). Temperatures at EE and the experimental Ascophyllum
stations (EL and EN, I'ig. 3) were interpolated, based on measured AT, and verified over several tidal
cycles with a portable thermistor and strip chart recorder.

Data Analysis

Relative abundance of intcrtidal organisms was estimated on the basis of percentage of substratum
covered by each taxon. Unoccupied substrata were classed as free space. Similarity between communities
was determined by a percent standardi/.ed form of the Bray-Curtis coefficient (Sanders 1960), calculated as:

where P(ii) is the percent of species (i) at station (j), P(ik) is the percent for station (k), and (n) is the
number of species in common. A flexible-sorting, clustering algorithm was applied to the resulting
similarity matrix. The calculations were performed on untransformcd percentages.

Ascnphvllum growth data are reported as mean growth ± 2 standard errors; means are compared using
2-sample t-tcsts (F'ROC TTEST, SAS Institute Inc. 1982). A probability level of n = 0.05 was used to

determine statistical significance. Ascophyllum mortality data are presented as the mean of years 1979-1986,
with vertical bars representing the range of values. As a special case, mortality at Fox Island excludes
1984 data, because the elimination oi Ascophyllum from FL in late summer of 1984 would bias comparisons
between F^'ox Island and other stations.

RESULTS AND DISCUSSION
Temperature Data

Ambient water temperature in the Millstone Bight area follows a predictable annual cycle. Maximum
daily average temperatures of 20-21 °C occur in August-September, with little variability among years.
Winter temperatures are more variable, ranging from 0 to -1 °C in a cold year (e.g., 1977), to 3-4 °C in
a warm year (e.g., 1983); yearly minima occur in January- February.

Condenser cooling water used by Millstone Units 1 and 2 is heated to 12-15 °C above ambient,
depending on reactor power level. Prior to August 1983, the heated effluent was discharged through a
single cut in the south end of the discharge quarry (Fig. 3); a second quarry cut was opened in anticipation
of the added volume of cooling water needed by Unit 3.

With one cut open and either 1 or 2 units operating, the effluent plume was directed to Twotrce
Channel where it was subjected to tidal flushing. Water temperatures within 75 m of the cut (FL
A.Kcopliyllum station; Fig. 3) were 2-3 °C above ambient, and temperatures at FF, were within 1 "C of
ambient regardless of tidal stage (Fig. 4, regime 1).

After the second discharge cut was opened the effluent plume lost half its momentum and mixed with
nearshore water, producing nearly isothermal temperatures along the shore between the cuts and the
southwest tip of Fox Island. During this time temperatures at Fox Island were 3-4 "C cooler than the
undiluted effluent (Fig. 4, regime 2), regardless of tidal stage. This resulted in temperatures at FF, 7-9 °C
above ambient when one Unit was operating (e.g., autumn of 1983), and 12-13 °C above ambient when
both Units were operating (e.g., most of 1984). Under these conditions, maximum water temperatures at
FF could exceed 30 °C.

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With three units pumping, the effluent plume was again directed into Twotree Channel where it was
subjected to tidal flushing. On the flood stage of the tide the effluent was directed westward, away from
Fox Island. During high tide, ambient water temperatures were recorded at FE, and temperatures at FL
were only 3-4 °C above ambient. On the ebbing tide, the plume was directed eastward across Fox Island.
Maximum temperatures, up to 8-9 °C above ambient, occurred at FE and FL at low tide. Minimum
temperatures were recorded 3 hours out of the 12 hour tidal cycle; elevated temperatures occurred during
the remainder of the 12 hour cycle. These conditions are modelled in Figure 5 and produce regime 3
temperatures illustrated in Figure 4 (note two curves for temperature at FE in this period). Water
temperatures are dependent on both the number of units operating and cooling water flow, and only when
all units are pumping will there be a tidal component to the temperature. Therefore, conditions are likely
to vary from year to year as each unit undergoes scheduled and unscheduled shut-downs. The effects of
these changing conditions will be examined in subsequent reports. Most of the data presented in this
report were collected under conditions modelled as regimes 1 and 2.

Qualitative Studies

Qualitative studies were designed to identify algal species presentin intertidal and shallow subtidal
areas in the vicinity of MNPS throughout the year, and to characterize their patterns of spatial and
temporal distribution. Changes in these patterns indicate environmental changes, and suggest a close
analysis of whether the changes were related to construction or operation of MNPS.

A rich and diverse flora occupies the rocky intertidal monitoring area, relative to other areas of Long
Island Sound. Overall, 158 algal species have been identified since 1979. Not all species were found at
any one station, nor were they all found in any one collection period, nor in any one year. Qualitative
algal collections for the monitoring period 1979-1985 are presented as number of times each species was
found in each month and at each station (Table 1). Complete collection records for each station are
presented in Appendix RS la.

The benthic flora of the Greater Millstone Bight can be separated into five divisions (sensu Whittaker
1969): Rhodophyta (reds), Phaeophyta (browns), Chlorophyta (greens), Cyanophyta (blue-greens), and
Chrysophyta (golden and yellow-green, including diatoms). In this study, blue-greens and diatoms are not
identified to lower taxa. The benthic algal flora can also be classified on the basis of life history, e.g..

131
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16

perennials, pscudoperennials, seasonal annuals, and aseasonal annuals. Perennials (species present as a
whole thallus throughout the year and persisting for more than one year) include Chondnis ch.spus,
Ascophyllum nodosum, and Fucus vesiculosus. Pseudoperennials (individual plants present throughout the
year but passing through adverse conditions in a reduced form) include Codium fragile. Seasonal annuals
(plants only found during part of the year) include Bangia atropurpurea, Desmarestia viridis, Cladophora
flexuosa, and Sphacelaria cirrosa. Aseasonal armuals (population as a whole present throughout the year
and capable of continual reproduction) include Uha lactuca and Enteromorpha flexuosa.

Of the 1 58 species of benthic algae found in our area, several were site-specific or characteristic of
only one station (Table 1), such as Laminaria digitala at TT, Ceramium deslongchampii at GN, Fucus
spiralis at BP, Bryopsis plumosa at FE, Polysiphonia nigrescens at WP, and Gelidium crinale at FS. In
addition, some species are abundant at only 2 or 3 stations, e.g., Pilayella littoralis at GN and FS, and
Pra.uola stipilata at GN, TT, and SE.

Temporal differences also occur, and seasonal components in the local flora have been identified.
Some examples include Bangia atropurpurea, Dumontia contorla, and Monostroma grevillei as most common
in winter-spring, Desmarestia viridis, Leathesia difformis, and Polysiphonia urceolata in spring-summer,
Champia parvula, Da.sya baillouviana, and Cladophora flexuosa in summer-autumn, and Callithamnion
tetragonum, Spermothamnion repens, and Sphacelaria cirrosa in autumn-winter (Table 1).

The persistence of these spatial and temporal patterns, and their consistency from year to year is an
indication of the stability of the local flora. Another measure of stability is number of species, i.e., species
richness.

The greatest number of species recorded from a single collection usually occurred in spring-early
summer for all stations. The most species collected in any month (1979-1985) was 1 17 in .July (Table 2),
and the fewest was 101 in March. TTie most species collected at any station since 1979 was l.'^l at BP
(Table ?i), and the least was 109 at both SF and TT. In each year, the greatest species number generally
occurred at WP (Table 4).

When division proportions are analyzed by month and station, proportions are similar and independent
of species number (Tables 2 and 3), providing another measure of floral stability. Annual percentage of

17

Number ot ipecier. coilcctsd in each division, by month { 1979-1985 combined), and
their percentage (in parentheses).

Division

total

Jan

Feb

Mar

Aor

Jun

Jul

Aug Sep

Oct

Nov

Dec

Rhodophyia 53(48) 47(44) 45(45) 45(41) 43(38) 45(40) 50(43) 56(51) 59(54) 53(49) 54(49) 56(51)

Phaeophyra 24(22) 30(28) 28(28) 32(29) 34(30) 29f26) 28(24) 25(23) 22(20) 26(24) 25f23) 23(21)

Chlornphyta 33(30^ 31(29) 28(28) 33(301 36(32) 38(34) 39(33) 29(26) 29(26) 30(28) 32(29) 31(28)

no

lOI

no

113

112

117

110

110

109

111

no

Table 3. Number of species collected in each division, by station (1979-1985 combined), and
their percentage fin parentheses).

Division

GN

BP

MP

TT

FE

F5

WP

SE

SS

total

Rhodnphyta
Phaeophyla
Chlnrophyta

56(45)
30(24)
39(31)

57(441
36(27)
38(29)

51(45)
30(27)
32(28)

54(50)
28(26)
27(25)

50(45)
26(23)
36(32)

54(44)

32(26)
38(31)

58(46)
33(26)
36(28)

48(44)
29(27)
32(29)

57(46)
31(25)
36(29)

73(46)
40(25)
45(28)

loiai

125

131

113

109

112

124

127

109

124

158

Table 4. Number of species at each station in each year (1979-1985), yearly totals, and

yearly division counts and percentages (in parentheses). Each 'year' represented by
collections from March to following February.

Stauon

1979

1980

1981

1982

1983

1984

1985

BP

72

70

94

86

80

85

73

FE

76

72

77

80

70

65

50

FS

71

69

72

80

79

82

65

GN

67

74

85

85

82

84

77

MP'

-

-

75

77

77

74

SE

58

55

71

73

69

70

63

SS

67

67

84

88

85

85

68

XT'

87

80

77

78

WP

72

^82

96

95

90

90

87

total

lUO

103

129

131

126

133

1 17

Division

Rhodophyia

44(44)

47(46)

60(47)

58(44)

57(45)

61(46)

54(46)

rhaeophyla

26(26)

26(25)

35(27)

35(27)

32(26)

34(25)

29(25)

Chlorophyta

30(301

30(29)

34(26)

38(29)

37(29)

38(29)

34(29)

species in each division (1979-1985) ranged from 44-47% for reds, browns 25-27%, and greens 26-30%
(Table 4), but the proportions of reds, browns, and greens vary seasonally (Table 2). Reds are more
prevalent, but especially so in August- December; browns are less prevalent than reds or greens, but have
their highest percentages in February-May; greens are proportionally most common in May-July. The
overall number of species in each phylum is 73 reds, 40 browns, and 45 greens (all stations, all years);
their proportion is 46:25:29 (Table 4).

The local flora, when represented as percent occurrence of reds, browns, and greens, is consistent with
those reported by other researchers in the northwest Atlantic (Vadas 1972; Schneider et al. 1979; Mathieson
et al. 1981; Mathieson and Hehre 1986). Vadas (1972) reported the proportion 45:32:23 on an open coast
in Maine. Mathieson et al. (1981), working in the Great Bay estuary system and adjacent open coast of
New Hampshire- Maine, reported the proportion 47:28:25, and Mathieson and Hehre (1986) updated this
study reporting a New Hampshire open coast proportion of 43:31:26. In a checklist of Connecticut algae
(including intertidal and subtidal species), Schneider et al. (1979) reported a proportion of 45:26:29, which
included 188 species, not including varieties and forms. Proportionally, the Connecticut marine flora as
determined by Schneider, is virtually identical to our own.

Exceptions to spatial and temporal trends are evident in the Fox Island -Exposed qualitative collections
after the opening of the second quarry cut in August 1983. The average number of species per monthly
collection was 31 from March 1979 to August 1983, and dropped to 28 in the year following the opening
of the second cut. A sharper drop in species richness occurred after August-September 1984. An average
of 18 species per month was collected from September 1984 to February 1986, and in October 1984, only
10 species of algae were collected from FE (the collection with lowest number of species from any station
in any month since the beginning of the study). Species richness decreased because physiological limits
of many species were exceeded; water temperatures at Fox Island exceeded 28 °C in August-September
1984 (NliSC^o 1985; also Appendix RS IV, Ecological Significance of Community Changes at Fox Island).
Community changes resulting from elevated water temperatures included the loss of established populations
of perennial macroalgae [Chondrus crispus, Fucus vesiculosus, Ascophyllum nodosum) and associated
epiphytes, and increased abundance and persistence of opportunistic species {Codium fragile, Enteromorpha
spp., Po/ysiphonia spp.). The changes were evidenced both as a loss of species, and a shift in relative
divisional proportions. From March 1979-August 1983 (prior to the second cut opening), 105 species were
reported at FE; 70 species were reported from September 1983- August 1984, the first year after the second

19

cut opening, and 67 species were reported from September 1984-September 1986, beginning one year after
the second cut opening. Proportions for the three periods were 43:25:32, 41:26:33, and 40:22:37, respectively;
noticeable is the decrease in browns and reds with a concomitant increase in the proportion of greens.
This shift in relative proportions in response to elevated water temperature was also seen in the quarry
collections, and will be discussed in the next section.

The floristic changes noted at FE were localized, and not indicative of more widespread effects.
Overall, the flora of Greater Millstone Bight has remained stable over time, and is similar to those studied
elsewhere in New England by other researchers (Vadas 1972; Wilce et al. 1978; Schneider et al. 1979;
Mathieson et al. 1981). The NUEL qualitative collections are important for predicting and assessing the
impact of 3-unit operation. These studies permit the determination of the degree of variability in seasonal
and yearly species occurrence. Qualitative differences in species composition among stations or years (as
noted at FE after 1983), as compared to species composition at the reference sites, can signal power plant
influence. Analyses of the flora in the years after Unit 3 becomes operational should indicate whether
possible thermal effects will be within present bounds or will spread to other reference sites.

Quarry Study

Qualitative algal collections from the Millstone quarry permit characterization of sites exposed to a
wide range of water temperatures, from ambient temperature when all reactors are shut down, to 21 "C
above ambient, when all reactors are at fuU power. Water temperatures change in response to varying
reactor power levels.

The overall quarry flora, composed of all species collected in the quarry or quarry cut, is similar but
not identical, to that of the NUEL rocky shore sampling stations reported in the previous section. Of the
118 species collected from the quarry or quarry cut, only 3 have not been collected at other NUEL
monitoring sites: Audouinella flexuosa, A. sagraenum, and Soroc.arpus micromorus. Those species found
at other sites but never in the quarry or the quarry cut are mostly cold-water reds, browns, and their
epiphytes. The relative proportion of reds, browns, and greens at the MNPS quarry (1979- 1986) was 46:21:33.

Some of the similarity between the quarry flora and that of the reference stations is due to periods of
ambient water temperatures in the quarry as a resuU of periodic reactor shutdown. Schneider (1981)

20

sampled algae from the Millstone effluent quarry over an 18 month period (including several shutdowns)
and found 42 species in the 3 major algal divisions, with proportions similar to those found in NUEL
quarry studies (Table 5). All species noted by Schneider except Spongomorpha arcta were present in our
quarry collections (this species was found in the quany cut). Schneider also reported the range of
temperatures over which each species occurred in his study area; relative algal proportions change with
elevations in water temperature, a fact also evident in NUEL quarry data. In Schneider's study and our
own, when temperatures exceeded 25 "C and 30 °C, a difference in species proportions became evident.
With elevated temperatures, the number of brown algal species decreased rapidly in the quarry, thereby
decreasing the proportion of browns relative to other groups. The relative proportions of species in each
algal division are similar in both Schneider's study and the NUEL quarry study (Table 5). Divisional
proportions are independent of species number and indicate phytogeographic afTmity (Druehl 1981).

Table 5. Relative proportion of each major algal division (reds, browns, greens) from New
England collections and MNPS quarry collections.

32:23
31:26
28:25

45:26:29
46:25:29
46:21:33
58:10:32
57: 3:40
45:24:31
50:12:38
57: 5:38

Maine open coast

New Hampshire open coast

Great Bay estuary and

NH-Maine open coast

CT intertidal and subtidal

reference sites

MNPS quany

>25°C

>30X
MNPS quany

>25°C

>30°C

Vadas (1972)

Mafhieson and Hehrc (1986)

Mathieson et a/. (1981)

Schneider et al. (1979)
NUEL (1979-1986)
NUEL (1979-1986)

Schneider (1981)

21

These phytogeographic affinities are also evidenced in the temporal distribution of components of the
quarry flora, relative to that of the reference sites. Species with southern centers of distribution (i.e.,
sub-tropical affinities), found mostly in summer and autumn in local rocky shore collections, had an
extended growing season in the quarry. For example, Agardhiella subulata ocurred mostly in summer
(May, June, .July) at the rocky intertidal collection sites, but occurred Ln every month in the quarry effluent.
Another red alga, Dasya baillouviana, was seasonal at reference stations (August- November) and found
only 83 times since 1979. Over the course of the quarry study, Dasya baillouviana could be found in any
month in the quarry. Similarly, Enteromorpha clathrata and Cladophora sericea, May-October greens at
most rocky intertidal sites, were much more common in the quarry and over a longer period. After
September 1984 at FE, Agardhiella subulata, Enteromorpha clathrata, and Cladophora sericea, among
others, were nearly as common at FE as at the quarry site.

In contrast, algae with more northerly distributions (boreal affinities, especially browns) were less
common in the quarry. Laminaria saccharina occurred each month at qualitative collection sites, but only
in March and April at the quarry. Similarly, Petalonia fascia, a November-.Iuly brown at nearby coastal
stations, occurred only in January and February at the quarry.

Qualitative algal collections from the MNPS effluent quarry are important because they characterize
a flora exposed to water temperature higher than those found at any nearby station. This flora therefore
reflects environmental conditions at one end of a thermal gradient; the floral characteristics of the reference
stations reflect ambient coastal thermal regimes. Differences in the quarry flora, i.e., reduced number of
species, especially browns, with increasing temperature, the resultant shift in divisional proportions, and
the temporal displacement (extension or reduction of an alga's growing season) are responses to this
thermal gradient. If the flora at a station farther from the discharge evidences similar floristic or vegetative
change, particularly after Unit 3 begins operation, a critical standard has been developed against which
thermal impact may be assessed.

Undisturbed Transects

One of the most noticeable biological features of local rocky shore communities is 7,onation; i.e., the
segregation of intertidal organisms into horizontal bands, each characterized by a particular complex of

22

plants and animals. This phenomenon is considered to be a universal feature of rocky shores (Stephenson
and Stephenson 1949, 1972; Lewis 1964).

Locally, we recognize three intertidal zones; identified as the high, mid, and low intertidal. The high
intertidal (Zone I), primarily bare rock, is seasonally occupied by barnacles {Balanus balanoides) and
ephemeral algae (mostly Ulothrix flacca, Bangia atropurpurea, Blidingia minima, or blue-greens). Fucus
(mostly F. vesiculosus, occasionally F. spiralis) may occur in small amounts in the high intertidal.

Barnacles and the fucoids Fucus vesiculosus and Ascophyllum nodosum dominate the mid intertidal
(Zone 2). Other algae in Zone 2 grow directly on rock (e.g., Ralfsia verrucosa, Enteromorpha spp.) or as
epiphytes of fucoids (e.g., Elachista fucicola, Polysiphonia spp.).

The low intertidal (Zone 3) is typically dominated by Chondrus crispus, though fucoids may also be
common. Barnacles are seasonally abundant, but usually obscured by an algal canopy. Other algae may
be attached to rock (e.g., Ralfsia, Corallina officinalis, Dumontia contorta) or to larger algae. Monostroma
pulchrum and Polysiphonia spp. are common ephemeral epiphytes.

The preceding description is not meant to imply that local intertidal communities are static or
homogenous; that is far from the case. Rather, the rocky shore is patchy, a mosaic of plants and animals
in dynamic equilibrium. Organisms compete for space, light, and nutrients. Processes of recruitment,
colonization, and growth are balanced against predation, senescence, and death. These processes vary over
space and time, on varying scales.

General patterns of spatial and temporal distribution may be illustrated by plotting abundance (mea-
sured as percent substratum coverage) over time for the major components of the local intertidal commu-
nities (I'igs. 6-10); data for all taxa are included in Appendix RS lb. In each case, data are presented as:
a) a time-series beginning in March 1979, to show long-term trends and year-to-year variability, and b)
all years combined, calculating monthly means ± 2 SE, to show seasonal trends. For example. Figure 6
presents barnacle coverage in each zone, and abundance of predatory snails (mostly Urosalpinx cinerea
and Thais lapillus) in Zone 3. Generally, barnacle coverage is highest in the mid intertidal (Zone 2) and
higher at exposed stations (e.g., BP, FE) than at sheltered stations (e.g., SS, FS). There are differences
between years, but most variability occurs annually, i.e., a seasonal cycle. Barnacles settle in early spring.

23

b)

barnacies ii pred. snails

§ ;:

i-^H

h—h'

Y-ft~^'f^r^^K^.^Y

JN FEB UAR APR UAY JUN JUL AUC SEP OCT NOV DEC
-- Zone 1 Zone 2 Zone 3 —Snails

1 a)

barnacle? St pred. snails

JtN FEB kUR APR kUY JUN JUL AUS SE? OCT NOV DEC
Zone 1 Zona 2 Zone 3

Figure 6. Abundance of barnacles and predatory snails as percent cover in each zone: (a) from March 1979-March
1986, and (b) monthly from 1979-1986, for GN, FS, FE, and DP.

a)

barnaclas i prod.

UW SEP UAJ( SEP UAR SEP UAR SEP U*R SEP UAR SEP UW SEP U«
lo-rn 198Q 1981 1M2 19" 198* 1985 198S

'1^ 2one 1 Zone 2 Zone :3 Snails

FEB UAR APR UAY JUN JUL AUG SEP OCT MOV DEC
Zone 1 Zone Z Zone 3 • Snails

UAR HP UAfi SP UAR SEP UAR 3EPUARSEPUAftSEPUARSEPUAR

-AN FIB UAR APR UAY JUN JUL AUC SEP OCT KCfJ DEC
Zone 1 — Zone Z Zone 3 — Snails

barnacles St pred. snails

UARSEPUAR^PUARSEPUARSETUAPSEPUARSEPUARSEP UAR
1 979 1 980 1 98 1 1 9B2 1 983 1 98* 1 985 1 98S

Zonal Zone Z — --Zone 3 —Snails

a)

barnacles i pred. snails

iM

UARSEPUARSEPUARSEPUARSEPUARSEPUARSEPUARSEPUAR
1979 1980 1981 1982 1983 ;98+ 1985 1986

Zone 1 Zone 2 Zone 3 — Snaiis

b)

barnacles Se pred. snails

/

N-

4.

^

^

'^^r''/

Y

■ ^-=i-^

\-^-

^r

'S

^^

^^

__-4

*-— 4=

-^=?:i

^

---,

.JN FEB UAR APR U»Y JUN JUL AUC
ion. 1 Zon.2 Zone 3

OCT NOV DEC
- Snaib

Figure 6. (cont.) Abundance of barnacles and predatory snaiis as percent cover in each zone: (a) from March
1979-Vlarch 1986. and (b) monthly from 1979-1986, for WP, SS. SE, and MP.

25

and coverage increases through early summer as individuals grow. By late summer, barnacle coverage
decreases, as individuals are lost to predation (especially in Zone 3), or desiccation (especially in Zone 1).
Barnacles may settle so densely or grow so quickly that they may eventually be lost to intraspecific
competition. Crowding and 'hummocking' (cf. Grant 1977) weakens an individuals attachment to sub-
stratum, and clumps of barnacles may be lost, especially during autumn storms (Foertch and Keser 1981).
Algae that have settled and grown on or between barnacles may also be lost with the removal of barnacles.
Another factor contributing to local barnacle mortality is predation; the most important predators in the
Millstone Pomt area are two carnivorous snails, Urosalpinx cinerea (oyster drill) and Thais lapillus (dog
whelk). These snails are most abundant in late summer, and are partially responsible for the decline in
barnacle abundance (cf. Hanks 1957; Bayne and ScuUard 1978; Foertch and Keser 1981).

Barnacles are also lost as a consequence of thermal stress. Throughout the NUEl. rocky shore
sampling program, thermal stress was a source of mortality only at Fox Island-Exposed, and only after
the opening of a second quarry cut in August 1983. Barnacle mortality was one of the changes observed
in the rocky shore community near the MNPS discharge following the opening of the second cut; the
changes are described and discussed in Appendix IV. Briefly, changes in water circulation patterns allowed
incursion of warm water to areas that were previously unimpacted (Fox Island-Exposed and the shoreline
between FE and the MNPS discharges). In spring, when ambient water temperatures were below 5 °C,
the thermal incursion was not detrimental to barnacles; at the time of peak barnacle settlement, maximum
temperatures at FE were ca. 12-14 °C. In March and April, dense bamacle set and rapid growth were
observed. However, in autumn, water temperature at FE exceeded 28 °C (see earlier Temperature Data
section), and barnacles were eliminated from this site.

Fucus vesiculosus is another important component in the northern Atlantic and local rocky shore
communities (Fig. 7). Peak abundance during the year usually occurs in late summer, following growth
of germlings that appear in spring; substratum coverage declines as plants are lost to autumn and winter
storms. There is also station-to-station variability in Fucm abundance; some stations have very low Fucus
cover (e.g., BP), others have consistently high cover (e.g., WP, SE). These patterns are related to degree
of exposure to waves; moderately exposed stations favor Fucus populations (Topinka et al. 1981). Fucus
cover also varies from year to year. At some stations (e.g., GN, FS), there appears to be a 3-5 year cycle
of Fucus abundance, related to the ecological life-span of this alga. Fucus does not propagate vegetatively
from a basal holdfast; rather, it occupies new substrata following settlement of zygotes and growth of

26

UAR SEP UAR SEP UAA SEP UAR SP UtA SS> UAR SEP UAR SEP UAjt
1 979 1 980 19B1 1 982 1 983 1 984 1 9U 1 98S

Zone 1 ^— Zone 2 Zone 3

UAR SEP UAH SEPUARSEPUMSEPUARSEPUARSEPUARSEPUAR

a)

^^^^0A!^^>...,^s,..^

SEP UAR SEP UAR SEP UAR SEP kMR SEP UAR SEP IMR SEP UAR
979 1980 1981 1982 19U 1984 1985 19S6
Zone 1 Zone 2 Zone i

1 b)

.^,jk^id^:^.^i=4^

JAN FEB UAR APR IMY JUN JUL AUC SEP OCT MOV DEC
Zonal Zone 2 — •- Zon« 3

Figure 7. Abundance of Funis as percent cover in each zone: (a) from March 1979-lVlarch 1986, and (b) monthly
from 1979-1986, for GN, FS, FE, and BP.

27

a)

LURSEPUARSEPUARSEPUARSEPUARSEPU«S£PUARSEPUAR
1979 1980 1981 1982 '9" 1984 1985 1986

Zone 1 Zone Z Zone 3

b)

:t;:it+i't4-^rt~t=-Tfc#==^

JW res UAR APR W.Y JUN JUL AUG SEP OCT NOV DEC
Zonal Zone 2 Zone 3

a)

b)

jAN FIB UAR APR UAY JUN JUL
Zone 1 ——Zone 2

a)

/\ / ^

•Zone 2 Zon« 3

b)

v-v-

+-4-F-"+-hh4^fl

JAN FEB UAR APR klAY JUN JUL AUC SEP OCT
Zone 1 Zone 2 Zone 3

o)

U»RSEJ"1MRSEPUARSEP1URSEPU»RSEPU*RSEP1«R3EP1UR
1979 1980 1981 1982 1980 1984 1983 I9B6
Zonal Zono Z Zone 3

Figure 7. (cont.) Abundance of Fucus as percent cover in each zone: (a) from March 1979-March 1986, and (b)
monthly from 1979-1986, for WP, SS, SE, and MP.

28

germlings (Knight and Parke 1950; Keser and Larson 1984). Typically, these germlings do not grow under
an established Fucus canopy. However, if an area in the mid intertidal is cleared (e.g., by ice-scour), Fucus
zygotes settle and grow into a new canopy, composed of plants of similar age. As these plants mature,
they become increasingly susceptible to epiphytism (Menge 1975), storm damage and ice-scouring
(Mathieson et al. 1982; Chock and Mathieson 1983). These processes tend to remove many plants at
once; plant loss opens new substrata for colonization, and the cycle of Fucus abundance is maintained (cf.
Schonbeck and Norton 1980; Keser and Larson 1984).

The decrease in Fucus cover at FE from 1980 through 1983 was another example of a cyclic pattern
in abundance. However, thermal impact resulting from water temperatures in excess of 28 °C interrupted
the Fucus population cycle at FE. The increase predicted after a settlement of germlings in spring 1984
failed to occur after thermal incursion and subsequent germling mortality.

Fucus cover also decreased at MiUstone Point, the station second closest to the MNPS discharges.
This decline may represent the descending portion of the same type of abundance cycle seen at FE, or it
may reflect a direct or indirect thermal effect. A direct effect might relate to the thermal tolerance of
Fucus; an indirect effect might be related to the observed increase in abundance of Liltorina littorea at
MP, and concomitant increase in grazing pressure on newly settled Fucus germlings. Other researchers
have shown that high grazer densities can retard Fucus recolonization for several years (Lubchenco 1983;
Keser and I.^rson 1984).

Chondrus crispw; is the dominant alga in low intertidal (Zone 3) and shallow subtidal areas near
MNPS, as it is throughout New England, the Canadian Maritimes, and Northern Europe (Mathieson and
Prince 1973). Chondrus populations were stable at all NUEL study sites, both within and among years
(Fig. 8). The decline in abundance seen at FE after the opening of the second quarry cut was due to
water temperatures in excess of 28 °C which eliminated Chondrus from FE in September 1984.

lypically, Chondrus is host to a variety of ephemeral epiphytic algae. In our area, the dominant
epiphytes on Chondrus are Monostroma pulchrum, Polysiphonia harveyi, and P. novae- angliae. These algae
have distinct seasonal peaks of abundance (Fig. 8), with Monostroma occurring in spring and Polysiphonia
in late summer-autumn. Some researchers have reported that shading by epiphytes is harmful to the

29

a)

Chondrtis & mOjOr epiphyte

UAftSEPUARSCPUARSO>UAR5EPlURSEPUAR5£?UARSEPUAR
1979 1980 19S)

Uonortroma —

a)

Chondrus ic major epiph/te

UAR ^EP UAR rEP UAR Sc7 UAP SEP UAR SEP UAR SEP UAR SEP UAR

FO UAR APR HAY JJN
— Uonosrtroma Poiysipho

SEP OCT NOV DEC
Chondrus

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
1 979 1 980 1 98 1 1 982 I 983 I 984 1 985 1 986

Poiysiphonia Chondrus

b)

CTumdrus Sc major spiphyti

JW FEB UAR APR UAY JUN JUL
Uonosiroma Polysiphonio

SEP OCT MOV

Chondrus

UARSEPUARSEPUARSEPUARSEPUARSEPUARSEPUARSEPUAR
\ 979 1 980 1 9B1 1 982 1 98^ 1 984 1 98S 1 986
Uonoatroma Poiysiphonia Chondrus

Figure 8. Abundance of Chondrus and major epiphytes as percent cover in each zone: (a) from March 1979-March
1986, and (b) monthly from 1979-1986, for GN. FS, FE, and BP.

30

°)

CTumd-rus i£ mojor epiphyt'

UAR SEP UAR SEP UAR SEPUARSEPUARSEPUARSEPUARSEPUAR
:979 1980 19SI 19S2 1983 1984- 1 9B5 1986
Uonostrofna Poiysiphonia Chondrus

JAN FEB UAR APR UAY JUN JUL

Uonostroma Polysjphonia

OCT NOV DEC

a)

CTwndrus ie major epiphyte

UAR3EPUARSEPUAR3EPUARSEPUAfirEPUARSS>UAft::EPUAR
■ 379 1 980 T 98 1 1 982 i 983 1 98* 1 985 1 986

Uonojrtroma Poiysiphonia Chondrua

.AN FEB UAR APR lUY JUN JUL AUG SEP OCT NOV
- Uonostroma Porysiphonia Chondrus

UARSEPUARSCPUARSEPUARSEPUARSEPUARSEPUARSEPUAR
1 979 1 980 1 98 1 1 982 1 983 1 984 1 985 \ 986

Uonostroma ■ Poiysiphonia Chondrus

a)

Cfumdrus ii major ep,phlrte

A,

U*RSEPU*RSEPU«)SEPlii«SEPU»R3EPU»RSE?U*RS£PU»R
1979 1900 1981 1982 1983 19B« 1983 1986
Uonofftroma poiysiphonia Chondrus

FEB UAA APR UAY JUN JUL AUG SEP OCT NOV DEC
- Uonostroma Polysiphonia Chondrus

FEB UAR APR UAY JUN JUL AUG SEP OCT NOV DEC
-— Uonostroma • Poiysiphonia Chondnjs

Figure 8. (cont.) Abundance of Chondrus and major epiphytes as percent cover in each zone: (a) from March
1979-iVlarch 1986, and (b) monthly from 1979-1986, for WP, SS, SE, and MP.

31

underlying Chondrns (Menge 1975; Lubchenco and Menge 1978); no such detrimental relationship was
evident from our data. Chondrus maintained high understory abundance.

Many other species of ephemeral algae contribute to the local intertidal community. Grouped by
division, some patterns are evident (Figs. 9 and 10). Generally, ephemeral algae are more common in
Zone 3 than in Zone 2, and more common at exposed than at sheltered stations. Many of these species
are opportunistic, and may occur at any time of year (e.g., Uha lactuca, Enteromorpha spp.), but others
show seasonal periodicity (cf Qualitative Studies section). For example, an increase in red algal abundance
in early spring was attributed to an increase of Bangia and Porphyra spp. Similarly, ephemeral browns
were most abundant in early summer (Apr.-July), corresponding to peak abundance of Petalonia and
Scytosiphon. Green algae, especially Enteromorpha spp., were most common in early spring and autumn.
Some of these abundance patterns were related to numbers and activity of grazers (Figs. 9 and 10). In
the MNPS area, littorinid snails (especially Littorina littorea) are the most important grazers, most active
in summer.

The abundances of major components of local rocky shore communities, and therefore the structure
and appearance of the communities themselves, vary over time and space. Variations are predictable, and
explainable in terms of seasonality, degree of exposure, and life-history of the organisms. Except for the
alteration noted at FE following the opening of the second quarry cut, changes to local rocky shore
communities have been minor, indicating stable environmental conditions during 2-unit operation. This
stability permits a characterization of each rocky shore station in terms of patterns of abundance of its
major community components. A measure of this stability is illustrated in Figure 11. Each station/year
combination is represented by the average annual percent cover of each species; Bray-Curtis similarity
indices were calculated for each pair-wise comparison. When these comparisons are plotted by applying
a clustering algorithm to the similarity matrix, the resultant dendrogram shows several levels of grouping.

The first level of separation distinguishes between unimpacted (group I) and impacted (group II)
collections. As previously described, the community that developed at FE in response to elevated water
temperatures was more like that found in the effluent quarry than at other sampling sites. Detection of
community alterations are evident from analyses of this type.

32

JAR SS> UAR SEP UAR SEP UAR SEP UAR S^ UAR SEP UAK SEP UAR

1 979 1980 1 98 1 1 982 1 983 1 S84 1 985 938

— Snails Reds Browns Greens

JM FIB UAR XPR UAY
Snails Reds

JUL AUG SEP OCT
- Browns — - Greens

a)

' ephemeral algae c

d grazers ,n zone 2

^A

/.

, X_

JAR lEP UAR SEP U« :eP U*R rEP UAR :EP UAR rtP -AR ZET' -Ai
■, 979 ; 960 ■ 98 1 1 982 i SS^S ; 98+ 985 ?^ -

b) ^"*-"

ephemeral algoe and grazers ;n zone 2

[ 1 f-H f— -1 — i ' f-

-AN FEB UAR APR UAY ^LJI

T,«C

1 aigce end gra

/•- •'"'_

-^

' '.---- ^-v

.'-.

■\'

T II'

v/V.

r-

N.

r)^

X /^^

OAR SEP UAR SEP UAR SG* UAR SEP UAR SEP UW SEP UAR SEP UAr?

FEB UAR APR UAY JUN JUL AUG SEP 0C7 NCTw DEC
— Snail* ■ Reds Browns — ■-Greens

SEP UAR SEP UAR SEP UAR SEP UAR , SEP UAR SEP UAR SEP UAR

b)

ephemeral algae and grcsers in zone Z

-i , i . ! h

-[ f

^AN FEB UAR APR

Snails Red:

Figure 9. Abundance of ephemeral algae and grazers in Zone 2 as percent cover: (a) from March 1979-IVIarch 1986,
and (b) monthly from 1979-1986, for GN, FS, FE, and BP.

33

A^_/v ^/^VJV-

yMSEPUAHSEPlWRSEPUWSEPUHRSEPUARSEPUHRSEPliW
1979 1980 1981 198Z 1983 198* 1983 198S
Snaito Rai' Browm Sreens

I-

FZB UAR APR UAY JUN JUL AUG SEP OCT NOV DCC
— Snail* R«ds Brown* Cr««n*

OAR SEP UAR SEP UAR SEP UAfl SEP UAR SEP WH SEP UAR SE? UAi?
1979 1980 -.981 1982 1983 198* 1985 :9a6

b)

«ph«m«fal algaa and grazers In zon« 2

-'K^.--

FEB UAR APR UAY JUN JUL AUG SEP OCT
— Snail* R«ds Brown* Greens

"^^J \j

1979 1980 1981 1982 1983 1984 1983 1986

Sndli R«d» Brown J Gr««n»

SEPU*RSEPl«RSEPl«RSEPll*RSEPU«!SEPU*BS£PU*fi
,981 1982 1983 198« 1985 1 98S
R«d» Brown* Gr««n»

■ Snails R«ii

Figure 9. (cont.) Abundance of ephemera! algae and grazers in Zone 2 as percent cover: (a) from March 1979-March
1986, and (b) monthly from 1979-1986, for WP, SS, SE, and MP.

34

b)

ephefneroi algae and grazers in zone 3

1 ■ M

A

^t\ ^_ .A^r^ /\_^

MR SSP UARSEPUARSEPUARSEPUARSQ^UARSEP UAR SEP UAR
t>7B 1980 1981 1982 1982 1984 1 9BS 1986

Snoll» Red» Browns Greens

-4--

.^.

JAN FEB UAR APR UAY JUN JUL AJJC SEP OCT
——Snails Reds Browns Greens

a)

ophemerol algae and grazers in zone 3

,__.^-'^-[-^-l-.^__

SEP UAR SEP UAR SEP UAR jHT UAR SEP UAR SEP UAR SEP UAR

,4^.

Mi FEB lUR tFR UtX iUH JUL AUG SE? OCT NCW DEC
Snails Reds Browns Greens

■ Snails Rods

U»RSEPU*«5EPtt»RS£PlMBSEPUARSEPU»RSEPUWSEI"U*R
UTS ISM 1981 1M2 1983 198* 1985 1988
Snails Reds

b)

ephemerol aJgoe and grazers in zone 3

i — { — I — . — -■ — I — • — I — ' — i-

^-^-^~~H-^^^.

-^~~yf~'~~^-

-Browns Greens

JAN FIB lUfl APR lUY JUN JUL «US
Snails Reds Browns

SEP OCT NOV DEC
- Gfeens

Figure in. Abundance of ephemeral algae and grazers in Zone 3 as percent cover: (a) from March 1979-March
1986. and (b) monthly from 1979-1986, for GN, FS, FE, and BP.

35

M_/VL-

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR

epnemeral algaa and grazers in rone Z

-f — -i — [ — p—r

-4-

-K^^^^l-^^.

-4

FtB UAR APR UAY JUN JUL AUG SEP OCT
— Snails Rods Browns — ■-- Greens

ral aigaa and grazers in zone 3

,-^../\_..__,-._/V-_.

^^ .'V.

—■^ /\_,—„-_A

— ■-■ -^-^

^■-, '-^, "- '^ ' .- ■

SSJ" li*H SEP UAR SEP
Snoils ' Reos

iE? UAR ic? UAR SEP UAR SEP UAS

FEB UAR APR UAY JUN JUL
— Snails Reds • 3ro

SEP 0C7 NOV DEC
Greens

,.A ..,

-!\^-^j '^-'

/ , y\ .-^^

lUKSEPUARSEPUARSEPUARSEPUARSEPUARSEPUARSEPUAR

— [—^"""^^^^-S. ---_._

--f^-^-

t-^,

.i/N FEB UAR APR UAY JUN JUL ^G SEP OCT UOJ XC
^^ Snails Reds Browns Greens

UAR SEP UAR SEP
1979 1980
Snails

b)

ephemeral algae and grazers in zone 3

I— +-^-^

.u__u-4-

'K.-

JAN FEB UAR APR UAY JUN ML AUO SEP OCT NOV DEC
Snails Reds Browns — --Greens

Figure 10. (cont.) Abundance of ephemeral algae and grazers in Zone 3 as percent cover: (a) from March 1979-March
1986, and (b) monthly from 1979-1986, for WP, SS, SE, and MP.

36

!J0|IUJ;2 4USOJ9J

37

IJnimpacted stations may be separated on the basis of those with little Chondrus cover in Zone 3
( < 25% on average; group lA) and those with greater Chondrus cover ( > 40%; group IB). These groupings
may be further subdivided on the basis of Fucus cover; groups IA2 (FS) and IBl average 30-40% Fucus,
groups lAl (SS) and IB2 average about 10%, and group IB3 (BP) with only a trace of Fucus.

Further subdivisions are based on species complexes unique to each station, and consistent over time.
The obvious pattern is for each station to resemble itself more than any other station. Fox Island-Exposed
is the only station to show clear changes over time. Collections from FE separate into periods when Fucus
was abundant (1979-81), when Fucus was less abundant (and collections were similar to those at Millstone
Point, 1982-83), and the period when FE was thermally impacted (1984-85).

In summary, local rocky intertidal communities, as represented in the undisturbed transects, have
undergone drastic changes in the immediate vicinity of MNPS, little change elsewhere. Analyses of data
collected during 2-unit operation show that community parameters vary within predictable limits, and that
the ob.served patterns of distribution and abundance of intertidal organisms may be explained in terms of,
e.g., seasonality, degree of exposure, intertidal height, inter- and intraspecific competition. Similar analyses,
using data collected during 3-unit operation, coupled with analyses of individual community components,
permit assessment of possible changes to nearby rocky shore communities, especially those that may be
affected by the 3-Unit thermal plume.

Recolonization Studies

Transects

Recolonization of denuded areas on local rocky shores is an on-going, naturally occurring process;
grazing/predation, storms, senescence, ice/sand scour all clear areas of intertidal rock, and make space
available for recolonization. Our recolonization experiments, therefore, allow isolation and identification
of some factors that influence the structure of local rocky shore communities. .luvenile stages of
recolonization organisms in the denuded transects could be more susceptible to power-plant effects than
adults in established populations, and comparisons of rates and patterns of community recovery under the
exclusion cages permit determination of the influence of grazing and predation on local intertidal community
structure.

38

As shown in the previous section (Undisturbed Transects), the shore community is divided into three
zones, each dominated by a specific biota: barnacles in the high intertidal, barnacles and fucoids in the
mid intertidal, and Chondrus in the low intertidal. Because of different life history strategies, each com-
ponent recovers at a different rate. Other factors that affect rates of recolonization include degree of
exposure, season of denuding, and inter- and intraspecific competition (Keser and I^rson 1984). For
example, the high intertidal is mostly barren rock, on which ephemeral cdgae, barnacles, and snails appear
seasonally. Many of the ephemeral algae are opportunistic, and readily colonize (at least temporarily)
available space. Mobile intertidal predators repopulate cleared substrata from nearby undisturbed areas as
soon as food availability and weather conditions permit. Therefore, the high intertidal may appear
'recovered' immediately after denuding, and similar in appearance to Zone 1 of nearby undisturbed transects
at the end of the first barnacle set. Percent cover values for all taxa found in the recolonization transect
studies are presented in Appendix RS Ic.

The mid intertidal of the local rocky shore community is dominated by a fucoid canopy over a
barnacle understory (Figs. 6 and 7). Recovery of these components is illustrated by plotting their abundance
(as percent cover) over time, compared with abundance in the undisturbed transects (controls). Figure 12
represents recolonization by barnacles in Zone 2 of the recolonization. transects. Following the spring
1979 denuding (made prior to the peak barnacle settlement period), barnacles settled heavily and, generally,
within two months were at least as abundant in the recolonization strips as in the control areas. The
exception was Giants Neck; at this station, most barnacles had already set at the time of denuding, and
subsequent settlement was lighter than at other stations. These barnacles grew through summer, and by
October 1979 barnacle coverage in the recolonization strips was as high as that in the controls. After the
autumn 1981 denuding (after barnacle set), barnacles were rare or absent in recolonization strips at all
stations until the following spring, after which their abundance paralleled that in the controls. The same
seasonal patterns of abundance were seen, i.e., settlement in spring, growth into summer, then decline in
cover in autumn and winter (cf. Undisturbed Transects section). At F'E, patterns of barnacle abundance
after the opening of the second cut (specifically, complete elimination in September 1984 and September
1985) were related to thermal incursion, and are included as part of the community changes described and
discussed in Appendix RS IV.

Recovery of the Fucus population in Zone 2 of the recolonization strips, relative to that in the
undisturbed transects (Fig. 13), was directly related to degree of exposure, hence the amount and duration

39

zone 2 I

Balamis at WP j

g denuding autumn denuding

UAR SEP UM! SEP UAR SEP UAR SEP IMK SEP UAR SEP UAR SEP UAH
1973 1980 1981 1982 1983 J 9S4 1985 1986
UNDISTURBED — RECOLONIZATTON

UAR SEP UAR SEP WAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
1979 ...l.SSiL 1981 1382 _J.983 ..._1.9a4.. 1985 1986

• UNDISTURBED

— RECOLONIZATION

£ « 111

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
1979 1980 1981 1982 1983 1384 1985 1986
UNDISTURBED RECOLONIZATION

zone 2
Balanus at FS

spring denuding

autumn denuding

n

M

'' i/l I

''I \

r V "\/ 1 1

v\

vw

M r

i ^

>/

\ 1' '

\ A "

1 '

1 h ; V

1 / ^

I

1

1 V

1

1

_'

■ UNDISTURBED

— RECOLONIZATION

Figure 12. Abundance of Balanus at recolonization sites in Zone 2, from March 1979-March 1986. Vertical lines
represent time of denuding.

40

zona 2
Fucus at WP

rpring denuding

UAR SEP VttR SEP UAR 3B> UAR SEP UAR SEP UAR SEP UAR SEP UAR
1979 1980 12gl 1932 1983 J 5.84 1935 1986
UNDISTURBlD — RECOLONiai ION

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP MAR SEP UAR SEP UAR
1979 1980 1981 1982 1983 1984 1 985 1986
UNDISTURBED — RECOLONIZATION

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP MAP SEP UAR
1979 1980 laei 1982 1983 1984 1985 1986
UNDISTURBED — RECOLONIZATION

• UNDISTURBED

— RECOLONIZATION

Figure 13. Abundance of Fucus at recolonization sites in Zone 2 from March 1979-March 1986. Vertical lines
represent time of denuding.

41

of available moisture. Following spring denuding, Fucus recovered at FE (the most exposed recolonization
station) in 8 months, at WP (2nd most exposed) in 14 months, at FS (2nd most sheltered) in 19 months,
and at GN (the most sheltered) in 29 months. After autumn denuding, the time needed for Fucus
abundance in the recolonization strips to approach that in the controls at FE, WP, FS, and GN were,
respectively, 16, 24, .36, and 36 months. Delay was attributed to the requirement for surface heterogeneity
to provide refuges from grazing; Littorina littorea prevent Fucus from establishing itself on smooth surfaces
(Lubchenco 1983). The community of the mid intertidal recovers (in terms of Fucus canopy) in as little
as S months (when denudation occurs prior to barnacle set, at an exposed station), or as long as 3 years
(when denudation occurs after barnacle set, at a sheltered station).

Recovery of the low intertidal (re-establishment of a Chondrus canopy) takes longer than recovery of
high or mid intertidal areas (Fig. 14). Chondrus propagates vegetatively from a basal crust; if the upright
axes are removed (e.g., by scraping or freezing) but the crust left intact, recovery of uprights may be rapid
(MacFarlane 1956). If, however, the crust is removed (e.g., by our methods of scraping and burning),
repopulation mu.st occur by settlement of spores. For Chondrus, repopulation initiated by spores is a slow-
process. After both spring and autumn denudings, Chondrus at GN and WP reached a maximum of only
5% cover after 30 months. In fact, during each 30 month experiment, the highest abundance of Chondrus
at any recolonization station was ca. 10% at FS after the autumn denuding.

Recovery of a Chondrus population involves long-term survival of relatively slow growing individuals.
This strategy is at the opposite end of a spectrum from that of ephemeral algae, that settle and grow
quickly whenever conditions are favorable. It also implies that even short-term periodic exposure to lethal
conditions will preclude re-establishment of Chondrus at FE.

Even under favorable conditions, interspecific competition for space from Fucus vesiculosus may
partially explain the slow recovery rate of Chondrus. Regardless of the time of year in which denuding
occurred, Fucus was the first perennial macroalga to colonize the low intertidal, and usually developed
into a dense canopy (Fig. 15). FoUowing experimental denudation of areas in dense Chondrus beds,
Lubchenco (1980) reported that Fucus colonized and persisted for at least 3 years. Chondrus settled and
grew under the Fucus canopy. Lubchenco predicted that when Fucus senesced (after its 3-5 year lifespan),
Chondrus would remain and exclude further Fucus settlement. In other words, Fucus initially out-competes
Chondrus, but eventually Chondrw; would dominate the low intertidal. Data from recolonization transects

42

I zone 3
IcTumd-ms crt WP

spring aanuding

V V

;\r-

100
90

zone 3

Chmidr\is <A GN
spring denuding

autumn denuding

ao

g so
o 1
z so

i «

30

hi

~-H/

'%:
H

20

10
0

'^:' \^-^^\^^^

- UNDISTURBED

-- REC3L0NIZAT10N

UAR SEP U*R SEP UAR S£? U(kR SEP UAR SEP HAS SE? UAR SEP WAR
1979 1980 1981 1982 1983 1984 1985 1986
UNDrSTURBED — RECOLONIZATION

zone 3

Chondrus ct Fc^
spring denuding

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
1979 1980 1981 1982 1983 1934 1985 1986
UNDISTURBED RECaLONIZATiON

zone 3

CTumdrus at FS
spring denuding

UAR SEP UAR SEP iUR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
T979 1980 1981 1982 1983 1984 1985 1986
UNDISTURBED — RECOLONIZATION

Figure 14. Abundance of Chondrus at recolonization sites in Zone 3, from March 1979-March 1986. Vertical lines
represent time of denuding.

43

-UNDISTURBED

RECOLONIZATION

- UNDISTURBED

RECOLONIZATION

I zone 3

I ■ F-ucus at Ft

'spring denuding

UAR SEP UAR SEP IMR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
1979 1980 198T 1982 1983 1984 1985 1986
UNDISTURBED — RECOLONIZATION

001

zone 3

1

Fucus at FS

i

801

spring denuding

autumn denudin

!

/'';

1
70

60

SO

,V

'v>

1

/ 1

40

I 1
1 1

/
I

30

^ I \ \

\,

20

'\h i

A^A

aA '

aV

10

J w

1 ^

W ;

V v^

' V

UAR SEP UAR SEP UAR SEP UMi SEP UAR SEP UAP SEP UAR SEP UAR
1979 1980 1981 1982 198J 1984 1985 1986
UNDISTURBED RECOLONIZATION

Figure 15. Abundance o[ Fucus at recolonization sites in Zone 3, from March 1979-March 1986. Vertical lines
represent time of denuding.

44

support this hypothesis; i.e., five years after denuding, Chondrus was established under the Fucus canopy
in Zone 3 at FS, GN, and WP (Fig. 14).

Barnacles also settle heavily in low intertidal areas (Fig. 16), more heavily under a Fucus canopy
(recolonization strips) than under a Chondrus canopy (controls). However, predatory snails have a greater
portion of the intertidal period to feed in the low intertidal, and barnacle mortality is higher than in Zone
2. Seasonal variability of barnacles is therefore more pronounced.

Results from recolonization transect studies conducted under 2-unit operating conditions support the
conclusions that: 1) different components of the community recover at different rates, 2) recovery is faster
at exposed stations than at sheltered stations, 3) when present, grazing snails can maintain smooth rock
surfaces free from algal coloniz.ation, and 4) they are prevented from doing so indefinitely because of
surface heterogeneity provided by barnacles. Obviously, spatial and temporal distribution patterns of
grazers and predators are important influences on the structure of local intertidal communities. We examine
influences of grazing and predation on recolonization in the next section.

Exclusion cages

Results from four series of exclusion cage experiments supplement conclusions relating to the effect
of .seasonality on rates and patterns of recolonization, and provide information on the effects of grazing
and predation. Reduction of interspecific competition separates the physical and biological factors, that
influence distribution of intertidal organisms. Thus, it is possible to demonstrate whether rates and patterns
of recolonization at Fox Island-Exposed were directly influenced by proximity to the MNPS discharge.
Fach series of experiments consisted of nine caged areas and nine control areas at each of four stations;
the information is synthesized into a model of community development, outlining common sequences of
events and alternate pathways. Complete percent cover data for each experimental area during each
denuding are included in Appendix RS Id.

General patterns of community development are illustrated in Figure 17. In each case, the vertical
axis represents relative, not absolute, abundance; absolute values varied among and within stations and
zones, but trends were similar. In general, values were higher at exposed stations than at sheltered, and
higher in mid and low intertidal areas than in Zone 1 , also higher under the cages than in the control areas.

45

UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR SEP UAR
1979 1930 1981 1982 1983 1984 1985 1986
....^vj<-.._j,« RECOLONIZATION

zone 3
Balanus at GN

spring danudinq | \ autumn denuding

- UNDBTUR^ED^

RECOLONIZATION

100

rone 3

90

tialanus at l-L

spring o.nuding

outL-mn denuding

ao

o

70
60
50

ivi

■ 1 ^' S

o

40

■ ■!

j 1 i i i

n.

30
20
10

n

i ii ;■!

mi

■UNDISTURBED

— RECOLONIZATION

•UNDISTURBED

— RECOLONIZATION

Figure 16. Abundance of Balanus at recolonization sites in Zone 3, from March 1979-March 1986. Vertical lines
represent time of denuding.

46

a) Zone 1

JASONDJFUAUJ
— aarnacles Ephemerals Fucus

b) Zone 2
spring danudinq

AUJJASONDJFUAUJ

— Barnacles Ephemerals Fucus

d) Zone 2

r denuding - opllon 2

JASONDJFUAUJJAS
— Barnacles Ephemerals Fucus

e)

Zone 2

autumn denuding

/

/

'"/Cr

'"--^...^ ^

ONDJ. FUAUJ
— Barnacles Ephemerals

A s 0 N D
- Fucus

f) Zone 2

wintflr denuding

■JFUAUJJASONDJFU
Barnacles Ephemerals Fucus

JFUAUJJASONDJFU
— Barnacles Ephemerals Mussels

h) Zone 3
option 2

J.FUAU.IJASONDJFM

— Barnacles Ephemerals Fucus

Figure 17. Models of recolonizadon community development under exclusion cages: a)Zone I, b-Q difTerent options
in Zone 2, and g-h) difTerent options in Zone 3.

47

As described in the previous section, the high intertidal (Zone 1) is mostly barren rock, with seasonal
occurrences of barnacles and ephemeral algae. Herbivory contributes to the structure of high intertidal
communities (Foertch and Keser 1981; Cubit 1984), but in general, physical factors are the controlling
influence (Menge 1975). Thus, the ephemeral algal turf that appears in spring in Zone 1 cages and control
areas is removed from control areas by grazing in early summer, and from caged areas by desiccation in
late summer. Barnacle settlement and growth are higher under the cages than in controls, but similarly
barnacles are usually lost from both areas with autumn desiccation. Degree of exposure had more effect
on community structure than did protection from grazing and predation. Growth and survival of barnacles
and ephemeral algae were higher at exposed stations (with more available moisture) than at sheltered
stations. For example, maximum barnacle coverage in Zone 1 cages at an exposed station exceeds 90%;
at a sheltered station less than 10% coverage. The seasonal cycles of settlement, growth, and mortality
were independent of the time of year in which denuding occurred (Fig. 17a).

In mid intertidal cages, initial stages of recolonization were dependent mostly on what reproductive
units were in the water column when space was made available, i.e., barnacles in spring, Fucus in summer,
ephemeral algae throughout the year (Fig. 17b-f). Unlike the recolonization transects, where a barnacle
set was prerequisite for development of a Fucus canopy (crevices between barnacles provided refuge for
Fucus germlings that were otherwise vulnerable to grazing), substrata denuded in summer was colonized
quickly ( < 1 month) by Fucus, if grazers were excluded.

Alternatively, exclusion of grazers retarded Fucus colonization, by permitting monopolization of sub-
stratum by ephemeral algae. In such instances, opportunistic algae occupied available rock, and Fucus
settlement was delayed until the following year. Both patterns are illustrated in the plot representing a
summer denuding (Fig. 17c and d).

In all Zone 2 denudings, it was apparent that exclusion of predators and grazers from mid intertidal
areas had more effect on the rate of recolonization than on the ultimate structure of the recolonization
community. Fach experiment ran for 15 months, but there was a clear indication that, had they continued,
the caged communities would have resembled nearby "undisturbed" communities, i.e., a Fucus canopy
over a barnacle understory. These findings support the conclusion that recovery from disturbance is
deterministic, even if transition states are variable (Paine 1984).

48

Recolonization was different in Zone 3 (low intertidal). The recolonization community developed
under the cages differently from the one that occurred when predators and grazers were not excluded. The
most common sequence of events is illustrated in Fig. 1 7g.

In Zone 3, Mylilus edulis set in early summer, even if barnacles already occupied available substrata.
Mussels gradually out-competed barnacles (and all other organisms) for space, and by autumn, typically
occupied 100% of the caged substratum. The mussels persisted as long as the cages remained in place.
The cages were removed when crowding prevented further community development. Mussels were lost
within 2-3 days, either washed away as a mass, or heavily preyed upon by Urosalpinx.

Alternatively, recolonization in Zone 3 could resemble that seen in Zone 2, i.e., development of a
Fucus canopy over a barnacle understory (Fig. 17h). These exclusion cage studies did not continue long
enough to determine the ultimate development of the low intertidal community. However, recolonization
transect studies discussed earlier show that re-establishment of a Chondrus population usually takes more
than 3-5 years. Exceptions occur and stochastic processes cannot be ignored. In one instance (specifically,
site 3 at White Point after the autumn denuding), Chondrus appeared in the cage area within 4 months,
and within a year, exceeded 85% cover. By contrast, Chondrus settlement never exceeded 5% in any of
the other experimental denudings. Obviously, recolonization is subject to natural variability.

One important result of the exclusion cage studies is the conclusion that recolonization at Fox
Island-Fxposed was not affected by proximity to the MNPS discharge; the patterns of development seen
at FF were similar to those at other stations. The series of exclusion cage experiments was completed
before the shore community was altered following the opening of the second quarry cut. These data will
be particularly useful for assessing potential effects of 3-unit operation.

The exclusion cage studies also show that grazers and predators exert their influence on local intertidal
communities, especially in mid and low intertidal areas, by preventing monopolization of space by a single
species (cf Menge 1975; Menge 1978). Grazers and predators help to maintain local communities in a
state of dynamic equilibrium, a balance between recruitment and growth, and senescence and removal.
This balance has persisted throughout the MNPS area during 2-unit operation. Where the community
balance has been disturbed (i.e., at FE following the opening of the second quarry cut), the community
responds to the changes as an entirety, and also in terms of its constituent species populations.

49

Ascophyllum nodosum Studies

Growth

Since 1979, the rocky intertidal monitoring program has included studies of Ascophyllum nodosum, a
large perennial alga that is abundant in the low and mid intertidal areas locally, as well as throughout
New England, the Canadian Maritimes, and Northern Europe. Ascophyllum has been studied extensively
throughout its range, and its vegetative and reproductive phenology is well documented (David 1943;
Printz 1959; Baardseth 1970a; Sundene 1973; Mathicson et al. 1976; Wilce et al. 1978). Ascophyllum
growth rate has been shown to be sensitive to water temperature changes, especially increases to ambient
temperature (Vadas et al. 1976, 1978; Stromgren 1977; Wilce et al. 1978; Keser and Foertch 1982). Because
of the alga's response to water temperature change and its mode of linear growth, this alga is an important
biomonitoring tool in the rocky intertidal program. Details of growth and mortality of local Ascophyllum
are summari/xd below.

From April 1979 through May 1983, Ascophyllum plants (tips) at Fox Island grew significantly longer
than those at White Point or Giants Neck (Fig. 18a); data from the reference stations did not vary between
themselves. In the year representative of this growth pattern, 1982-1983, Ascophyllum tips grew longer
because of the 2-3 "C AT at FL under single quarry cut conditions (see Temperature Data section),
showing a higher growth rate earlier in spring and an extended growing season in late autumn (Fig. 18b).
Tlie increased tip length at FF resulted from faster growth from April to July. Growth rate during the
remainder of the year was similar to growth rates at the control stations. Annual growth was similar to
growth recorded for Ascophyllum populations throughout its geographical range (cf. Vadas et al. 1976,
1978; Stromgren 1977, 1983; Wilce et al. 1978; Keser and Foertch 1982).

During the 1983-1984 growing season, FL water temperatures were 2-3 °C above ambient from April
to luly, and average tip length was significantly longer at FI, than at the control sites (Fig. 19a). After
August 1983 when the second quarry cut opened and only one unit was in operation, the water temperature
at V'V, rose to 7-9 °C above ambient and plants were exposed to a maximum temperature of about 27 °C.
Growth rate at FF decreased sharply from August to October when temperatures decreased (Fig. 19b);
tissue damage and some deformed tips were observed. When both units were operating in spring 1984,
elevated water temperatures (12-13 °C above ambient, ca. 20 °C at the end of April 1984) were within the

50

range of temperatures for optimal growth of Ascophyllum. Average tip length and growth rate were
significantly greater at FL than at the control sites.

When two units were operating, with discharge through two quarry cuts, as in the 1984-1985 growing
season, water temperature averaged 12-13 °C warmer than at the control sites, resulting in high initial
growth at FL in April-June (Fig. 20a). In July, temperatures exceeded 25 °C and growth rate at FL
decreased sharply (Fig. 20b); in July some tagged plants had tiny bladders and many lateral proliferations.
By August, water temperatures exceeded 28 °C and Ascophyllum plants died at FL. Ascophyllum at GN
and WP had a predictable epiphyte flora and appeared healthy. Other researchers have related increased
water temperatures to physiological stress. Chock and Mathieson (1979) found the maximum net
photosynthesis for summer Ascophyllum nodosum plants to occur at temperatures between 18-21 °C with
a "conspicuous decrease" beyond 24 °C. Thermal injury to Ascophyllum was determined between 30-35
°C (Kanwisher 1966), while enhancement at 22 °C, gradual demise at 26 "C, and complete thalJus
destruction at temperatures above 30 °C was modelled by Vadas et al. (1978).

A second Fox Island station was established in April 1985, following the loss of Ascophyllum at FL
in 1984. This new station was located at the first available Ascophyllum population around Fox Island-
Exposed, approximately 200 m from the discharges (Fig. 2); water temperature at FN was 0-2 °C warmer
than at controls in spring 1985 (with only two units in operation). Ascophyllum growth at FN was higher
than at the control sites from April to May, but for the remainder of the growth season neither average
tip length nor growth rate differed significantly between FN and GN (Fig. 21).

Temperature measurements made during periods when Unit 3 was testing its circulating water pumps
in summer of 1985 (thereby increasing effluent volume) indicate that during 3-unit operation, FN will be
exposed to water temperatures 2-3 °C above ambient. Thermal plume predictions indicate that WP may
also be exposed to warmer water. Comparison of Ascophyllum growth under 3-unit operating conditions
to data collected during 2-unit operation will permit assessment of the extent of the plume.

Mortality

Ascophyllum mortality, determined as thallus breakage, is a response to mechanical and environmental
stress. Thallus breakage could occur above the base tag, either between the base tag and the colored tie

51

wL'Ncj

E
£ 2C

c

2 -

AFRS2 JUNfiZ AUGc2 00732 DECa2 FE3S3 AF?tS3 JUNe3

DATZ
FL GN WP

Figure 18. Ascophyllum gro\vth, 1982-1983: a) as average tip length, and b) as average monthly increments. Data
are plotted as means i2 standard errors.

52

2 ICC

JL•^^c- Au:

CCTc3

n.

AP=='

JL'Mc-i

WF

E

E 2C

if '-
c

^ ic-

2nd cut coenec

0-. :

AFKZ2 JUNaZ AUG22 CCTSZ DEC23 FTE54 AFF.a4 JUNa4

DAIZ

FT. g:j W

Figure 19. Ascophyllum growth, 1983-1984: a) as average tip length, and b) as average monthly incremenL';. Data
arc plotted as means ±2 standard errors.

5.1

175-

1£0-

a)

A-^

:44-+f

AFHH- -UNc-; al'g;

CCTH-i DECS-i FI5=5 APRS

DA7Z
GM WF

JUNE;

:o-'

E

£ 20

c

IE

S 51

-k--i

r--T..I .A

4
/ \

^^-^T-1^

-F-

>.

APHS4 JUNa4 AUGa4 0CT84 DECa4 Ft=E5 AFRS5 JUNBS

DATE
Fl GN WP

Figure 20. Ascophyllum growth, 1984-1985: a) as average tip length, and b) as average monthly increments. Data
arc plotted as means ±2 standard errors.

54

0--

JL'N£;

AL'GG;

FN

ccTcs decs;

DATZ
G.N WF

FlEHo APR25

JUNcc

zc-'

V 10-

b)

V-^'

APFvSS JUNS5 AUG35 OCToS DEC35 FEBE5 APRae JUNHB

DATE
FH GN WP

Figure 21. Ascophyllwn growth, 1985-1986: a) as average tip length, and b) as average monthly increments. Data
are plotted as means ±2 standard errors.

55

wrap used as a tip tag, or between the tip tag and the growing apex. To determine if the causes of
mortality differed between stations, tip mortality was examined in two ways: as surviving tapes, and as
surviving tapes with at least one viable apex (Figs. 22 and 23). Ix)ss of tip tags implies mechanical removal
and immediate loss of plant material. Loss of viable apices and/or damage to the apical cell implies a
potential loss of biomass due to lack of growth.

Factors that contribute to Ascophyllum mortality include epiphytization (e.g., by Pofysiphonia lanosa,
Ceramium ruhrum, Ec.tocarpus siliculosm) and grazing (especially by Littorina oblusata). Both of these
processes increase the likelihood of breakage during storms. Thermal stress was evident only at Fl, < 1
month after the opening of the second quarry cut, and in the following year, tagged Ascophyllum plants
were eliminated from FL by September 1984.

Since 1979, Ascophyllum plant loss averaged ca. 60% and tip loss ca. 80% (NUSCo 1986). In general,
there was much year-to-year variability in plant and tip mortality. Prior to the opening of the second
quarry cut, mortality was never associated with proximity to the MNPS discharge. Maintenance of stable
populations, despite high measures for loss of plant material, is an indication of both the high degree of
productivity of Ascophyllum, and the importance of this plant in contributing to the detrital pool of the
marine ecosystem. Similar conclusions, and similar rates of mortality have been reported by other
researchers in New England (Vadas et al. 1976; Wilce et al. 1978).

Ascophyllum is not expected to recolonize at FL, even though conditions may be favorable for most
of each year. Since repopulation involves long-term survival of individuals (as discussed earlier for
Chondrus), even short-term exposure to lethal water temperatures in summer prevents Ascophyllum recovery.
The substratum previously occupied by Ascophyllum in this area will continue to be dominated by
ephemeral algae. We must emphasize, however, the localized scale of this impact, i.e., less than 150 m of
shoreline. Sampling of populations more distant to the discharge will continue to provide information to
the rocky intcrtidal monitoring program. In particular, analyses of growth during ,3-unit operation permits
determination of whether thermal effects may be seen over a larger area.

56

JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

Fox Island

JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

Figure 22. Ascnphyllum mortality, as number of surviving tagged plants. Means of monthly values from 1979 to 1986
are plotted with their ranges.

57

250-

\^

200'

^-

ISO

^

100

--^

50

Giants Neck

1 ~"

250-

^

-^^

200-

Q-

P

y

Q

\

O

ISO'

\

^

\

o

\

a

2

Z

100

Fox Island

^^

__^

50

__

~^

JUL AUG SEP OCT NOV DEC JAN FEB MAR APR

OCT NOV DEC ■ JAN FEB MAR APR

Figure 23. Ascophyllum mortality, as number of surviving tagged tips. Means of monthly values from 1979 to 1986
are plotted with their ranges.

58

SUMMARY

1 . Water temperature is an important environmental parameter afTecting local rocky intertidal communities.
At sampling stations exposed to ambient water temperatures, communities closely resemble those
studied throughout New Bngland. The Millstone area flora has exhibited consistent patterns of spatial
and temporal distribution during 2-unit operation. Since 1979, 158 species have been reported: 73
reds, 40 browns, and 45 greens. Quantitative studies show intertidal /.onation patterns typical of rocky
shores throughout New England: the high intertidal was dominated by barnacles, the mid intertidal
by barnacles and fucoids, and the low intertidal was dominated by Chondrus. Degree of exposure to
waves and storms played a determining role in the structure of rocky intertidal communities, either
directly by minimizing desiccation and providing nutrients, or indirectly by influencing the distribution
of grazers and predators. Changes to local rocky shore communities have been minor (except for the
alteration at FE after the second cut opening) and predictable, based on naturally occurring cycles,
indicating that environmental conditions during 2-unit operation have been stable.

2. The intertidal community at Fox Island-Exposed was unimpacted by 2-unit operation, prior to the
opening of the second quarry cut in August 1983. Subsequent qualitative and quantitative collections
show exceptions to the typical spatial and temporal trends noted elsewhere (and evident at FE
previously). Physiological limits of many species were exceeded at 28 "C in late summer 1984, resulting
in a decrease in species number at FE. Perennials were replaced by opportunistic species (ephemerals);
a decrease in browns with a concomitant increase in greens with extended temporal patterns was
reported. The resulting community resembled that found in the discharge quarry.

3. Recolonization experiments were undertaken to isolate factors that influence the stnicture of local
rocky intertidal communities. In the Millstone area, recolonization was influenced by time of year in
which denuding occurred, and it was related to degrcx of exposure and intertidal height. For example,
-ecolonizafion was rapid in the high intertidal of an exposed station and slow in the low intertidal of
a sheltered station.

59

4. Results from exclusion cage studies support conclusions made earlier, i.e., Fox Island-Exposed was
unimpactcd prior to the opening of the second quarry cut. Rates and patterns of recolonization, both
with and without the influence of grazers and predators, were unafTccted by proximity to the discharge.

5. Ascnphyllum nodosum is an important biomonitoring tool in the rocky intertidal program because of
its response to water temperature change and its mode of linear growth. Analyses of tip length have
allowed us to distinguish between an impacted population exposed to water temperatures 2-3 "C
above ambient and populations at two reference stations. Further, the response of the experimental
Ascophyllum population, especially after the opening of the second cut, allows us to assess the effects
of sublethal and lethal water temperatures.

CONCLUSION

Rocky intertidal studies performed during 2-unit operation show that local rocky shore communities
are in a state of dynamic equilibrium; settlement, recruitment, and growth are balanced by senescence and
removal (by both physical and biological interactions). Most of these processes are cyclic, and we have
identified their temporal and spatial variability. We have also determined the effect of elevated water
temperatures on these processes, and documented floristic and vegetational changes in an established
community close to the MNPS discharge. If similar changes occur at stations more distant to the MNPS
discharge, the NUF.F rocky intertidal studies constitute a base-line from which to assess potential impacts
associated with Unit 3 operation.

60

REFERENCES CITED

Baardseth, E. 1970. Synopsis of biological data on knobbed wrack Ascophyllum (Linnaeus) LeJolis.
FOA Fisheries, Synopsis #38, Rev. 1.

Bayne, B.L., and C. ScuUard. 1978. Rates of feeding by Thais (Nucella) lapillus (L.). J. Exp. Mar.
Biol. Ecol. 32:113-129.

Chapman, V.J. 1946. Marine algal ecology. Bot. Rev. 12:628-672.

Chock, .I.S., and A.C. Mathieson. 1979. Physiological ecology of Ascophyllum nodosum (L.) I^.Iolis
and its detached ecad scorpioides (Homemann) Hauck (Fucales, Phaeophyta). Bot. Mar. 22:21-26.

. 1983. Variations of New England estuarine seaweed biomass. Bot. Mar. 26:87-97.

Connell, .1.11. 1961. Effects of competition, predation by Thais lapillus and other factors on natural
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66

3 T1S3 OnSflEll 5

Contents

BENTHIC INFAUNA 1

INTRODUCTION 1

MATERIALS AND METHODS 3

Chronology of Previous Sampling Protocols 3

Current Sampling Practices 5

DATA ANALYSES 7

Statistical Modeling 7

Biological Index Value 10

Species Diversity 11

Numerical Classification and Cluster Analyses 11

INTERTIDAL RESULTS 12

Sedimentary Environment 12

General Community Composition 12

Community Dominance 15

Community Abundance 17

Numbers of Species 20

Species Diversity 20

Cluster Analysis 23

INTERTIDAL DISCUSSION 25

INTERTIDAL CONCLUSIONS 26

SUBTIDAL RESULTS 27

Sedimentary Environment 27

General Community Composition 29

Community Abundance 31

Numbers of Species 31

Dominance 36

Species Diversity 39

Cluster Analysis 40

SUBTIDAL DISCUSSION 41

SUBTIDAL CONCLUSIONS 43

REFERENCES CITED 44

APPENDICES 51

BENTHIC INFAUNA

INTRODUCTION

The benthic infauna are relatively small inconspicuous organisms that inhabit intertidal beach and
subtidal bottom sediments. Infaunal communities are generally composed of worms (polychaetes and
oligochaetes), clams and small crustaceans and collectively, they play a vital role in maintaining ecosystem
productivity. For instance, many infaunal organisms are important prey species for demersal fishes
(Woodin 1982; Moeller et al. 1985; Witman 1985; I,e Mao 1986) and thus form an important linlc tn
energy transfer pathways in the food chain. Their contribution to primary production in marine
environments, though less conspicuous, is of equal importance. Many studies have described the
influence of infaunal feeding, burrowing and tube building activities on nutrient recycling (Goldhaber et
al. 1977; Aller 1978; Hylleberg and Maurer 1980; Raine and Patching 1980). The importance of this
recycling process was documented by Zeitzschel (1980), who estimated that 30-100% of the nutrients
required by shallow-water phytoplankton are derived from the sediment; the activities of the benthos
often enhance this nutrient release.

Infaunal organisms are also useful environmental monitoring tools. These species are relatively
sedentary and thus are often exposed to and cannot escape the anthropogenic stress. Further, the
manner in which infaunal communities respond to stress is highly predictable (Boesch 1973; Reish 1973;
Sanders et al. 1980; Boesch and Rosenberg 1982; Young and Young 1982; Rees 1984). For example,
a physically stressed community is usually comprised of a few characteristically abundant species (e.g,
Polydora ligni, Capitella spp. and Mediomastus ambisetd) which rapidly invade after disturbance or are
capable of tolerating environmental stress (McCall 1977; Reish et al. 1980; Sanders et al. 1980).

To evaluate impacts based on the abundance and species composition of infaunal communities
assumes that the organization of natural, undisturbed communities can be established, and that the
direction and extent of any natural trends can be identified (Nichols 1985). Many studies have shown
that cold winters (Beukema 1979), storms (Boesch et al. 1976), or heavy rainfall (Jordan and Sutton
1985; Flint 1985) and changes in such biological factors as competition and predation (l^vinton and

Stewart 1982; Woodin 1982; Moeller et al. 1985) can strongly influence the abundance and composition
of infaunal communities. As a result, the structure of natural infaunal communities oscillates around
an equilibrium point and the range can only be established through long-term studies (Holland 1985).

The sampling of infaunal communities to identify environmental impacts associated with construction
and operation of the Millstone Nuclear Power Station (MNPS) began in 1969, one year before start-up
of Millstone Unit 1, has continued interrupted since that time. Environmental changes associated with
construction and operation of MNPS include: bottom scour near the intake and discharge structures
caused by water currents; chemical and heavy metal additions to the water; dredging near the intake and
discharge structures and increased water temperatures due to cooling water discharge. To assess the
degree of impact of these power plant induced changes on infaunal communities, the MNPS benthic
monitoring program was designed to:

(1). Describe infaunal community abundance and composition at subtidal and intertidal stations located
within and beyond areas influenced by operation and construction of the MNPS,

(2). Identify spatial and temporal patterns in community structure and establish the extent and direction
of natural changes in these communities.

(3). Evaluate whether any observed changes in infaunal communities were the result of construction
and/or operation of MNPS and; if so, assess their ecological significance.

Since 1975, the long-term infaunal program has centered on assessment of impacts that might occur
during 2-unit operation. In recent years, additional short-term studies were implemented to provide data
that will be used to assess nearfield impacts that result from Unit 3 start-up. These studies included an
investigation of the infaunal community inhabiting the Millstone Discharge Quarry (Appendix BI-I) and
a study of infaunal organisms inhabiting the area of the discharge cut (Appendix BI-II). The following
report is intended to summarize results of the long-term sampling prior to the commercial operation of
Unit 3 (April 1986) and is intended to establish a baseline for assessing impacts that might occur during
3-unit operation at the Millstone facility.

MATERIALS AND METHODS

Since the beginning of infaunal monitoring, numerous modifications in sampling procedures and
laboratory techniques have been implemented to improve the quality of the data (Table 1). A chrono-
logical description of program changes are provided below; however, details of these changes, including
justification for, and the overall effect on the data, are provided as appendices to this report.

Chronology of Previous Sampling Protocols

Sampling of infaunal organisms began in 1969, with studies of intertidal habitats. These studies
provided comparisons between population sizes of the gem clam. Gemma gemma, at a potentially
impacted station (Jordan Cove) and a reference station (Giants Neck). This program also provided
meiofaunal biomass estimates; however, organisms were not identified. Sampling methods used during
these studies (May 1969 through March 1973) were developed to obtain abundance estimates of primarily
one species, thus corrmiunity parameters that are currently used to assess environmental impacts can not
be calculated. These data have been summarized elsewhere (Hillman et al. 1973) and will not be
considered further in this report.

In March 1973, the scope of the benthic infaunal program was expanded and reflected adoption
of a "community" approach to assess environmental impacts rather than an "indicator species" approach.
In addition, sampling of subtidal habitats began and an additional intertidal station was established.

Since 1973, the "community" approach to evaluating power plant impacts has continued, although
modifications in sample size, numbers of replicates, collection locations and schedules, preservation
methods, and mesh size used to process samples have influenced the data. For instance, the practice
of freezing samples, (from 1973 to June 1976), resulted in the loss of up to 75% of the organisms
(NUSCo 1982). These data can not be quantitatively compared to subsequent data and will not be
used in any future study of potential impacts of the Millstone facility.

Infaunal data collected in June and September 1976 were analyzed to assess the adequacy of ten
replicate cores in sampling infaunal communities at each station (Battelle 1977). Results identified the
patchy distributions of infaunal organisms and concluded with a recommendation that increased replication

5 0, L
S 3 S

S U.

might help integrate small scale patchiness and thus provide better estimates of density, species diversity
and patterns in community composition. Following this report, a more intensive study examined the
effects of sample size on the various parameters used to characterize infaunal communities (e.g., species
area curves, indices of dispersion, species diversity, abundance, dominance patterns) (Battelle 197R).
Results showed that larger cores (25-cm (i.d.) x 10-cm deep) were more effective than smaller cores
(10-cm (id.) X 5-cm deep) in collecting less abundant species, although significant differences in density
were evident for only three species. Based on this study, a recommendation for increasing the numbers
of replicate cores from 10 to 15 was implemented in March 1979. In addition, samples were processed
with a 0.7 mm and a 0.5 mm mesh sieve to provide a comparison of the numbers of individuals retained
by each sieve. Because of the increased numbers of replicates, several sampling stations were eliminated
and use the 10-cm core was adopted to allow sufficient time to process the additional samples.

In 1981, data collected during the previous two years were analyzed to evaluate the effects of 15
vs 10 replicates (NlJSCo 1982). This study revealed that 10 cores were needed to collect 90% of the
species found in 15 cores. Species composition was similar using both methods, overall estimated
densities were not significantly different, and the estimates of community variance were not substantially
lower based on 15 replicates. Based on this study, the replicate number was reduced to 10 cores per
station/quarter. As might be anticipated, use of the smaller mesh sieve significantly increased both the
numbers of individuals and species collected (NUSCo 1986).

Current Sampling Practices

From March 1979 to March 1986, infaunal communities were sampled at four subtidal and three
intertidal stations (Fig. 1). The Giants Neck subtidal (GN-S) and intertidal (GN-1) stations are located
5.5 km west of the power plant and serve as reference stations. The Intake subtidal station (IN-S) is
located 0. 1 km seaward of the Millstone Uriit 2 intake structure and the Fffluent subtidal station (EF-S)
is approximately 0.1 km offshore and adjacent to the cooling water discharge into Long Island Sound.
The FF-S station is located as close to the effluent as possible given the current produced by the
discharge. Jordan Cove subtidal (JC-S) and intertidal (JC-I) stations are located 0.5 km east of the
power plant and based on thermal plume mapping studies (and modeling of Unit ?>) (NUSCo 1983) are
located in areas potentially influenced by the plant discharge during two and three-unit operation. The

Figure 1 . Map of the Millstone Point area showing the location of intertidal and subtidal sand sampling stations.
(CiNI, JCI and WPI = Giants Neck, Jordan Cove and White Point intertidal stations; GNS, FFS, JCS,
INS = Giants Neck, RfTluent, Jordan Cove, and Fntake subtidal stations).

White Point (WP-I) intertidal station is farther east of the power plant (1.6 km), but is still within an
area potctilially influenced by plant discharge, particularly when all three units are operating.

At each subtidal and intertidal station, ten 0.007R m cores (10 cm diameter x 5 cm deep) were
collected quarterly (March, .lune, September and December). F'or reporting purposes, a sampling year
begins in September and ends in .lune, and the year of the .lune sample assigned as the sampling year.
Subtidal samples were taken within 3 m of each station marker by SCUBA divers. Each sample was

placed in a 0.333 mm mesh Nitex bag and brought to the surface. Intertidal samples were collected at
approximately 0.5 m intervals parallel to the water line at mean low water.

Samples were brought to the laboratory and fixed with a 10% buffered formalin/rose bengal
solution. After a minimum of 48 h, organisms were floated from the sediments onto a 0.5 mm mesh
sieve and the float and residue were preserved separately in 70% ethyl alcohol. Organisms were removed
under dissecting microscopes, sorted into major groups (annelids, arthropods, molluscs, and others),
identified to the lowest possible taxon and counted. Taxa not quantatatively sampled by our methods,
(e.g., nematodes, ostracods, copepods, and foraminifera) were not removed from samples.

A 3.5-cm diameter x 5-cm deep core was taken at the time of infaunal sampling and sediment
analysis performed using the dry sieving method (Folk 1974). His method of moments technique was
used to calculate the arithmetic mean phi, which was then converted to mean grain size.

DATA ANALYSES

This report includes data that were collected from March 1979 through March 1986, the last
sampling period prior to commercial operation of Millstone Unit 3. Quarterly results from this period
arc presented either on Tables within the text or attached as Appendices. When analyses are based on
annual means or annual totals, only data comprising an entire sampling year (e.g., the September,
December, March and .Tune quarters) are used. In this report, data collected in March and June 1979,
September and December 1985 and March 1986 were not used in analyses involving annual means
because they do not constitute an entire sampling year.

Statistical Modeling

Multiple regression techniques were used to minimize natural sources of variation and thus improve
the sensitivity of analyses designed to identify year to year differences in animal abundance and numbers
of species. Data used were log-transformed quarterly mean densities (no. /core) and quarteriy mean

numbers of species (no./core) collected from March 1979 through March 1986. As noted previously,
natural temporal and spatial fluctuations in infaunal communities often reflect environmental changes
due to climatic conditions or to life history cycles of the organisms comprising these communities. To
remove this natural variation, the following were used as explanatory variables in our multiple regression
models:

A. Precipitation

Daily precipitation records compiled by the U.S Weather Bureau at the Groton Filtration Plant
were obtained from June 1976 through March 1986. Values to the nearest 0.01 inch were used as our
"rain" data for the regression model.

B. Water and Air Temperature

Ambient water temperatures (at the Millstone Intake Structures) and air temperatures (at the 33-foot
level of Millstone meterological tower) were extracted from the Northeast Utilities Environmental Data
Acquisition Network (EDAN). Daily averages, based on observations made at 15-minute intervals, were
calculated for the period June 1976 to March 1986.

C. Wind Speed and Direction

Wind speed and direction (at the 33-foot level of the Millstone meterological tower) were extracted
from the EDAN database at 15-minute intervals from June 1976 to March 1986. These values were
used to calculate a Wind Index which weighted wind speed according to wind direction. A NOAA
navigational chart of the sampling area was used to calculate site-specific wind direction weights according
to the particular wind direction responsible for potential wave-induced sediment disturbances at each
sampling station. The directional weight ranged from 0, when wind would not influence the station, to
1, when the wind could result in waves directly affecting the area. The Wind Index was then computed
by multiplying the directional weight times the wind speed. Because the effect of wind was assumed
to be cumulative, daily averages were derived using only Wind Index values greater than 0 (i.e., wind
direction and speed during the 15-minute periods when such wind-induced effects could have occurred).

D. Sedimentary Parameters

Sedimentary parameters (e.g., mean grain size and silt/clay content) were obtained as part of the
monitoring studies and the quarterly values for each used as explanatory variables in the regression analyses.

E. Climatic Extremes (Deviations)

Additional variables were created to represent periods of extreme climatic conditions which have
occurred during the sampling period. High or low deviations were derived for each abiotic factor as the
difference between the quarterly mean or daily value and the ten year mean for that quarter. Deviations
based on quarterly means were intended to examine the effects of longer term extremes (i.e., an unusually
cold winter), while those based on daily values were intended to remove the effects of shorter-term
episodic events (i.e., storms). Daily deviations were averaged and summed (for cumulative effects) over
each sampling quarter.

F. Seasonal Reproduction-Recruitment Component

Many infaunal organisms in the Millstone area exhibit annual peaks in abundance, which often
reflect the seasonal nature of annual reproduction and recruitment cycles or periods of favorable climatic.
Spectral analyses of quarterly data showed that annual cycles in community abundance and numbers of
species were present. To account for this periodicity, harmonic terms having a period of 1 year were
included as explanatory variables in the regression models.

In ail, .12 abiotic variables were available for the analyses (28 climatic variables, 2 sedimentary
charateristics and 2 seasonal harmonic components).

Model Selection Procedure

Lx)ng-term trends in the quarterly mean values were first detrended using a polynomial regression
equation. If no significant long-term trend was evident, residuals were created by subtracting the quarterly
mean from the six-year mean. A stepwise multiple regression on these residuals was then used to select

relevant abiotic variables and combinations of variables that were significant at a probability level of
a < 0.1 5. This probability was deemed sufficient to guard against fitting more parameters than can be
reliably estimated, given the sample size. The model that minimized the mean square error and
maximized the R-square was selected as best describing observed variablity in abundance and numbers
of species.

Analyses of covariance were then conducted to test for annual differences in abundance and species
using significant explanatory variables as covariates. Results of these analyses and pair-wise t-tests on
adjusted means (least square means) were used to identify significant (a < 0.05) long-term and annual
differences species abundance and number.

Although some abiotic factors were not independent of each other, all variables were initially
included in the stepwise regression analyses, because our objective was to identify and remove the natural
temporal variability and thus improve our ability to detect power plant related changes. Future analyses
of data collected during 3-unit operation will be directed to identifying the extent and effect of individual
abiotic factors in structuring local infaunal communities.

Biological Index Value

The Biological Index Value (BIV) of McCloskey (1970), an index of dominance, calculated using
annual totals of the 10 most abundant taxa at each station collected from 1980-1985. Species were
ranked according to their total abundance in each sampling year and the ranks summed for all years.
To calculate the BIV, the sum for each taxon was expressed as a percentage of a theoretical maximum
sum that would occur if a species ranked first in all sampling years. For example, the BIV would be
equal to 100"''o and the theoretical maximum equal to 60 when a species ranks first in abundance in
each of six years and a total of 10 species are collected.

10

Species Diversity

Species diversity for each station was calculated using the Shannon information index:

where n i = number of individuals of the i species, N = total number of individuals for all species and
S = number of species. An evenness component of diversity was calculated as:

./ = ^^ {Pielou 1977)
"max

where II max ='"8 S and represents the theoretical maximum diversity when all species are equally
abundant. Evenness ranges from zero to one and increases as the numbers of individuals among species
become more evenly distributed. Diversity calculations excluded oligochaetes and rhynchocoels (groups
that sometimes accounted for over 80% of the totals organisms collected) because they were not identified
to species. Similarly, other organisms that could not be identified to species, either because they were
juveniles or in poor physical condition, were excluded from this analysis.

Numerical Classification and Cluster Analyses

Cluster analyses, based on annual abundances of organisms were performed using the Bray-Curtis
similarity coefficient. This coefficient is calculated as:

li^tj + ^ik)

Sji^ = -%; {Clifford and Stevenson 1975)

where X |j = abundance of attribute i at entity j and X jk = abundance of attribute i at entity k. Based
on these similarities, cluster analyses incorporating a flexible sorting strategy (B = -0.25) was used to form
station groups (lance and Williams 1967).

INTERTIDAL RESULTS
Sedimentary Environment

The JC station is a semi -protected, southeasterly facing beach that is seasonally exposed to waves
produced by southeast winds (primarily during fall and winter storms). The sediment at this station is
composed of medium to very coarse sands; mean grain size since March 1979 ranged from 0.3 - 1.3
mm (I'ig. 2). These sediments generally contain only 1-3% silt/clay and large amounts of eelgrass
{Zoslera marina) and algae often cover the beach. The beaches at GN and WP face southerly and are
exposed to the prevalent south to southwesterly winds which occur in the Millstone area. Wave scour
produces clean, sandy beaches composed of medium sand which ranged from 0.3 to 0.8 mm in sb,e
since 1980; silt/clay content at these stations has been consistently low (< 1%).

During the monitoring period, temporal fluctuations in sediment grain size and the percentage of
silt/clay have been characteristic of the JC station and possibly reflect the more seasonal nature of
erosion and accretion cycles. In contrast to JC, sedimentary characteristics of the GN and WP beaches
have exhibited temporal stability, both seasonally and annually and is probably due to more uniform
exposure to wave induced scour.

General Community Composition

I'he 720 samples collected at the three intertidal beaches during the baseline period yielded 135
taxa and 69,448 individuals. Since 1980, communities have been dominated by polychaetes and
oligochaetes, which frequently accounted for over 75% of the total number of individuals collected
annually (Table 2). The JC community was dominated by the oligochaetes, which accounted for 40-86%
of the individuals collected in each of the last six years. At GN and WP, polychaetes were generally
most abundant and oligochaetes accounted for less than 40% of the individuals. At these stations,
rhynchocoels were often an abundant component of the community. In terms of species number,
polychaetes were most numerous and, although arthropod and mollusc species were present at JC and
GN, these groups accounted for less than 5% of the total individuals collected.

12

STATION- GIANTS NECK

Grain Size (-•-•-•)
Silt/Clay (-+-+-+)

MAR79 MARaO MARS1 MARB2 MARS:! UARa4 UARSS MARae

STATION: JORDAN COVE
Brain Sizo (-.-.-«) ,
Silt/Clay (-+-+-+)

■3 i<

MAR79 MARBO MARai UAR82 MARa3 MARa4 UARas UARB6

STATION: WHITE POINT

Grain Size (-.->-•)
Silt/Cloy (-+-+-+)

hlAR79 UARSO MARai MAR82 MARa3 MARa4 MARS5 MAR86

Figure 2. Quarterly mean grain size (mm) and silt/clay content (%) of sediments sampled at Millstone intertidal
stations from March 1979 - March 1986.

13

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14

Quarterly numbers of species, total numbers of individuals and relative abundances from September
1979 to March 1986, for each major taxon collected at intertidal stations are presented in Appendix I.
Highest abundances of polychaetes and oligochaetes generally occurred in September or June. Molluscs
and arthropods, more common in the JC community, have also been most abundant in either September
or June. Rhynchocoels, an important component of the GN and WP communities, were generally most
abundant in colder months (December and March).

In the three 1986, sampling periods (September/ December 1985 and March 1986), there were
temporal shifts in general community composition evident at all intertidal stations. For instance,
polychaete species number at WP and GN stations was lower than all previous observations in the
September collections. The total number of individuals at WP in September was lower than most
previous observations. The GN and WP stations also had relatively low total numbers of individuals
in December and March collections, lower numbers of polychaete species and total numbers of species
in the December collections. Although the three JC sample periods were similar to most previous
sampling periods, the total number of individuals in December was sightly lower. The JC 1986 March
collection was among the highest for total numbers of species and individuals recorded for that period.

Community Dominance

Since 1980, intertidal communities have been numerically dominated by species of polychaetes,
oligochaetes and rhynchocoels, and during this period, only one one arthropod {Gammarus lawrencianm)
and one mollusc {Gemma gemma) species have accounted for more than 5% of the total individuals
collected (Table 3). Only Scolecolepides viridis, Polydora ligni, and oligochaetes were among the
dominants at all stations. At GN and WP, 9 of 10 numerical dominants were the same over the
baseline period. In contrast, six of the top ten most abundant taxa at JC were dominants at only this
station.

Sandy beach communities in the Millstone Point area were typically comprised of a few taxa that
occurred in high densities over all sampling years, along with less abundant forms that exhibited temporal
variations over the monitoring period. This was particularly true at JC, where oligochaetes accounted
for over 60% of all individuals in 5 of the past 6 years and was the most abundant taxon in each of
the last six sampling years (BIV= 100%). Scolecolepides viridis and Hediste dtversicolor were the orily

15

Percent contribution and Biological Index Value (BIV) 'of the ten most numerically abundant taxa
at Millstone intertldal stations in each year, September 1970 - June 1985.

Giants Neck

Rhynchocoela
llaploscoloplos f ragils
Scolecolepides viridis
Paraonis f ulgens
Oligochaeta
Capttella spp.
Hedlste diversicolor
Polydora ligni
Mtcrophthalmus sczelkowii
Tharyx acutus
Gammarus lawrencianus
Streptosyllis arenae
Neohaustorius biarticulatus
Haustorius canadensis
Pygospio elegans
Lepldonotus squamatus
Polydora socialis

32

15

20

19

6

1

<1

2

<1

1

<1

0

0

1

<1

0

0

22
26
18
13

4
11

5
<1

1
<1
<1

0
<1
<1
<1

0

0

10

10

21

40

6

4

2

1

<1

<1

1

I

<1

0

1

0

12

23

11
9

37
9
6

<1
0

<1
1

<1
0

<1

<1
0
0
0

7
12
28

4
30

8
<1

4
<1

0
<1

1
<1

0
<1

1

0

19

19

5

2

40

9

2

1

1

0

<1

<1

<1

<1

0

0

0

90.2
89.2
85.3
84.3
83.3
75.5
53.9
52.9
47.1
36.8
35.8
32.9
32.8
31.9
27.9
20.6
19.6

Jordan Cove

Oligochaeta

87

64

70

81

40

86

100.0

Scolecolepides viridis

8

6

13

10

32

4

94.4

Hedlste diversicolor

2

20

I

1

21

4

88.1

Polydora ligni

• <1

1

<1

3

2

1

77.4

Capitella spp.

1

2

1

2

1

2

77.0

Gemma gemma

1

5

<1

<1

1

<1

68.3

Gammarus lawrencianus

<1

<1

14

1

<1

<1

65.1

Rhynchocoela

<1

<1

<1

<1

<1

<1

60.7

Gammarus mucronatus

<1

<1

<1

<1

<1

<1

53.2

Streblospio benedict!

<1

<1

<1

1

<1

<1

52.4

Microphthalmus sczelkowii

<1

<1

<1

<1

0

<1

44.0

Lacuna vincta

<1

0

<1

<1

<1

<1

41.3

Pvgospio elegans

<1

0

0

5

<1

<1

40.9

Nereis succinea

0

<1

<1

0

0

<1

38.9

Leptocheirus pinguis

0

0

<1

1

<1

<1

35.3

Eteone longa

<1

0

0

0

0

0

34.9

Crepidula plana

<1

0

<1

0

<1

<1

31.3

Edotea triloba

0

<1

<1

<1

<1

<1

31.0

Phoxocephalus holbolli

0

0

<1

0

<1

0

22.2

Potarailla reniformis

0

0

0

0

0

<1

21.8

White Point

Rliynchocoela
llaploscoloplos f ragilis
Paraonis f L-lgens
Oligochaeta
Streptosyllis arenae
Capitella spp.
Scolecolepides viridis
Parapionosyllis longicirrata
Exogone hebes
Polydora ligni
Pygospio elegans
Hedlste diversicolor
Aricidea catherinae
Mytilus edulis

39

34

13

40

39

19

95.6

21

21

15

31

23

11

92.1

8

12

34

7

15

26

89.5

4

12

26

12

16

31

88.2

4

4

6

7

1

3

77.2

9

2

<1

<1

<1

4

66.7

4

7

<1

<1

<1

1

60.5

<1

1

1

2

<1

<1

53.1

<1

<1

<1

<1

<1

<1

46.1

4

2

0

0

<1

1

45.6

0

2

<1

<I

0

<1

42.1

1

<1

1

0

0

<1

38.6

0

0

2

0

<1

<1

37.3

0

0

<1

<1

<1

<1

33.3

16

other taxa that had relatively high BIV's ( > 80%) and consistently accounted for over 5% of individuals
during the period. And although Capitella spp., Polydora ligni, and Gemma gemma have consistently
ranked among the dominants, they usually were found in low densities relative to other the top three
taxa.

At GN and WP, rhynchocoels, Paraonis fulgens, and H aploscoloplos fragilis were dominant, con-
tributing over 10 percent of the total individuals and having BIV's over 80% indicating their consistent
abundance over years. In addition to the above taxa, Scolecolepides viridis was a consistent dominant
at GN and Slreptosyllis arenae at WP.

Community Abundance

Quarterly mean abundance (no. /core) of intertidal communities along with predicted values from
multiple regression models are given in Figure 3. From March 1979 to March 1986 infaunal abundance
(the exponential of values in Figure 3) ranged from 4 to 95 at GN; 18 to 840 at .IC; and from 2 to
143 at WP. Overall, the .IC community included more organisms, than GN and WP which were of
similar magnitude. On a seasonal basis, intertidal organisms were generally more abundant during
warmer sampling periods (June and September) than during colder ones (March or December). However,
no consistent trend was common to all stations.

Multiple regression models removed 59%, 20% and 60% of the variability in abundance at GN,
.IC and WP, respectively. Plots of annual means after adjusting for this natural variation are presented
in Figure 4. The analysis of variance, based on adjusted annual abundances revealed that no significant
long-term trends in abundance have occurred at any intertidal station between 1980 and 1985.

Pairwise comparisons, based on t-tests, indicated that the annual mean abundance at .IC^ during
1982 was significantly lower than those observed in 1983 and 1985. At GN, the 1984 value was
significantly higher than those of 1981 or 1983. At WP, annual density in 1983 was significantly lower
than those found 1981 or 1982; 1985 density was also significantly lower than 1982;

17

station: GIANTS NECK INTERTIDAL
R ^ = 0.59

Station: jORDAN COVE INTERTIDAL
R ^ = 0.20

Figure 3. Quarterly mean numbers of individuals per core and multiple regression predictions for Millstone intertidal
infaunal communities sampled from March 1979 - March 1986.

Figure 4. Annual mean abundance per core with two standard errors for intertidal infaunal communities sampled
from September 1979 - June 1985. (Annual means were adjusted using analysis of covariance which
included abiotic and climatic conditions as covariales.) .g

Numbers of Species

Quarterly mean numbers of species (no. /core) from March 1979 - March 1986 ranged from 1 to
10 at GN; 3 to 13 at JC; and < 1 to 9 at WP"(Fig. 5). As with overall community abundance, the
number of species was highest at JC, while at GN and WP numbers of species were similar. The
seasonal trend in the numbers of intertidal species was similar to that of density, being higher in
September and .June than in March or December.

Abiotic variables used in the multiple regression models accounted for 60% (GN), 63% (.IC) and
62% (WP) of the total variation in species numbers. After removing this variation, no long-term trends
in species numbers were evident at any station since 1980. Plots of annual adjusted mean numbers of
species illustrated the stability of this community parameter during the monitoring period (Fig. 6). In
addition, t-tests of adjusted annual means identified significant interannual differences between the 1982
and 1984 values at JC; all other pairwise comparisons between years were not significant.

Species Diversity

Annual mean species diversity (H') over the study period ranged from 1.2 to 2.3, and evenness (J)
from 0.4 to 0.7 (Table 4.). The mean numbers of species and individuals included in diversity calculations
ranged from 6 to 17 and 97 to 580, respectively. On an annual basis, no consistent spatial or temporal
shifts in H' have occurred over the monitoring period. Other parameters (S, J, N), reflected spatial
differences in the structure of intertidal communities. For example, at GN and WP both the numbers
of species and individuals was generally lower than at JC.

Quarteriy values of species diversity from September 1979 to March 1986 for intertidal stations are
presented in Appendix II. Highest values of H', S and J commonly occurred in September at all
stations. For the three sample periods in 1986, H', S and J attained historical low values in the GN
September and December collections. At JC, H' and J were low in December relative to previous
values of these indices. Given the temporal variation of diversity parameters at WP, the values in the
1986 collections were considered similar to previous years.

20

station: GIANTS NECK IHTERTiDAL
R ^ = 0.60

MARSO MARB1

UARS3 MAR84 MARS5 MARSS

14

Station: jQRDAN COVE INTERTIDAL
R= = 0.63 •

12

•

•

10

A

A

A

o

o

a

z\ / \ / \ / \

ft

/ \

a.

6

1 / ^

12

o

a.
m

4

/ \. / • Vy I

j

\.l

f

\i

2

2

0

a •

\j

W

UARS2 MAR83 MARa4 MARSS

UARSO UARS

UARS2 MARS3

MARSS MAR86

Figure 5. Quarlcrly mean numbers of species per core and multiple regression predictions for Millstone intertidal

infaunal communities sampled from March 1979 - March 1986.

21

10

STATION: JORDAN COVE

8

,'

..--

o 6

\

""i ''

Il-

\

/•'

l/I
D-

'•,

,.-''

,

2

1982 1983 1984 1985

10

STATION: WHITE POINT

8

cr
o 6

a:

Q-

-

10

"--,

o 4

Q-

"

2-

Figure 6. Annual mean number of species per core with two standard errors for intertidai infaunal communities
sampled from September 1979 - June 1985. (Annual means were adjusted using analysis of covariance
which included abiotic and climatic conditions as covariatcs.) 22

Table 4. Annual mean species diversity CH' ) , evenness (J), species number (S),
total individual (+ 1 standard error) collected at Millstone
incertldal stations from September 1979 - June 1985.

Giant Neck

1.9+0.3 1.7+0.2 1.5+0.4 1.3+0.2 2.2+0.5 1.7+0.4

0.7+0.1 0.6+0.1 0.4+0.1 0.5+0.1 0.6+0.1 0.5+0.1

9 + 3 10+1 13 ±1 ^±1 13 + 3 9 + 2

322 + 202 202 + 73 368 + 61 162 + 87 220 + 112 149 + 54

Jordan Cove

1.5+0.5 1.7+0.5 1.6+0.5 1.7+0.5 1.5+0.4 2.3+0.1

0.4+0.1 0.4+0.1 0.5+0.2 0.4+0.1 0.5+0.1 0.5+0.1

12 + 2 15 + 5 9 + 2 17 + 4 12 + 4 21 + 3

267 + 127 421 + 160 309 + 230 558 + 162 581 + 249 580 + 237

White Point

2.2+0.1 2.1+0.2 1.2+0.2 1.5+0.1 1.4+0.2 1.7+0.4

0.6+0.1 0.7+0.1 0.4+0.1 0.6+0.1 0.4*+ 0.1 0.5+0.1

12+2 1113 10+2 ' ± 2 10+1 11+2

193 + 53 275 + 101 337 + 148 97 + 39 181 + 63 182 + 58

Cluster Analysis

Cluster analysis, based on annual species counts since 1980 produced two major station-time groups
tliat reflected differenres between community structure at .!(" and those found at GN and WP (Pig. 7).

23

0 -

10 -

20 -

N-

.10 -

rr

i

40 -

2

in

50 -

1-

X

60 -

tc

UJ
CL

70 -

80 -

90 -

^ % cj^ % c^ % <?;. ^ ^ ^ ^ ^ '^c -^c ^o^ t^^ '^c t-^

Figure 7. Dendrogram resulting from classification of annual infaunal collections at Millstone intertidal stations from
September 1979 - June 1985.

The first major group of station/years (Group I) included all WP and GN collections and was father
subdivided into two subgroups, (jroup A contained CjN years, and the 1985 WP collection; similarity
among these station/years and their separation from other collections was due to shared high numbers
of oligochaetcs and 1 1 aplnscoloplos fragilis. Subgroup B (remaining WP years) separated from other
years because of very high densities of rhynchocoels, Streptnsyllis arenae and Paraonis fulgens.

The .ICr collections (Group II) had relatively low similarity with GN and WP because of the high
numbers of oligochaetcs, Scolecnlepides viridis, Hediste diversicolor and Polydora ligni found at JG. The
relatively high similarity among most .IC years reflected temporal constancy in the species composition
at this station and the level of similarity among years was dependent on variations in the abundance of
taxa rather than shifts in composition. For example, the subgroup containing 1981, 1982, 1983 and
1985 coUccticins included very high numbers of oligochaetcs, and high numbers of Polydora ligni, Capitella
spp. and Gammaf-us lawrencianus. Collections from other years, had similar species composition, but
densities of these species were considerably lower.

24

INTERTIDAL DISCUSSION

Intertidal infaunal beach communities were dominated by annelids, with arthropods, molluscs and
rhynchocoels being locally abundant. The structure and composition of these communities contrasts
sharply with haustoriid amphipod communities that have been reported as typical of more exposed
sandy beaches along the coasts of North America (Croker et al. 1975; Croker 1977; Dexter 1969) and
are more typical of annelid dominated communities reported from more sheltered estuarine areas (Withers
and Thorpe 1978; Mauer and Aprill 1979; Tourtellotte and Dauer 1983).

Although the level of wave exposure within LIS is probably lower than ocean exposed beaches,
wind and wave energy appears to be a major structuring force within the Millstone area. Throughout
the monitoring program, all measures used to describe infaunal communities have consistently illustrated
the spatial similarity of the GN and WP communities and their dissimilarity from that of JC. The
shallow-sloping, clean sandy beaches of GN and WP, reflect their constant exposure to wind and
wave-induced scour. Generally low numbers of species and individuals are found at these beaches and
dominant components include Haploscoloplos fragilis, Paraonis fulgens, rhynchocoels, and Streptosyllis
arenae, taxa which are typically found in sandy habitats (Dexter 1969; Whitlatch 1977; Maurer and
Aprill 1979; Tourtellotte and Dauer 1983).

The clean medium sands consistently found at GN and WP contrasts sharply with the sedimentary
environment at .IC. The .IC station is protected from constant wave scour, except during periods of
strong southeast winds. Flere the sediments are less uniform in size, exhibit larger seasonal shifts in
size, contain higher amounts of silt/clay and are frequently covered by large amounts of algae or eelgrass.
Infaunal abundance and numbers of species have been typically much higher at .IC than at either CjN
or WP; differences in density are primarily caused by very high densities of oligochaetes. Other organisms,
including molluscs and arthropods have been frequently more abundant at .IC than at other stations.
In intertidal sand habitats, higher numbers of these organisms generally occur in areas of increased shelter
from wind-induced stress (Croker 1977, Maurer and Aprill 1979). The dominant components of the
.IC community include oligochaetes, Hediste diver.sicolor, Capitella spp. and Polydora ligni, species which
can utilize fine organic matter as a food source (Sanders et al. 1962; Whitlatch 1977; Caspers 1980;
Knott et al. 1983). High abundances of these taxa may also be enhanced by the detrital mat which

25

covers the JC beach throughout much of the year; this mat can significantly influence the numbers and
types of species found inhabiting intertidal beaches (Soulsby et al. 1982).

Seasonal and year-to-year fluctuations in intertidal community abundance and composition were
evident throughout the Millstone sampling program. However, an extensive evaluation of seasonal trends
in species abundance are not appropriate because the sampling is performed only four times per year.
A more important consideration, from the monitoring standpoint, is the removal of natural, temporal
variation that can significantly reduce our ability to identify power plant related impacts on infaunal
communities. Intertidal communites are strongly influenced by physical environmental conditions
(Holland and Polgar 1976) and interannual variations in these conditions are expected to effect rather
large changes in the overall abundance and composition of these communities. Attempts to model this
variation at the community level, using abiotic factors as explanatory variables, removed 20-60% of the
total variation in community density and 60-63% of the variation in numbers of species observed since
1980. After adjusting for the effects of the variation in these factors, both the average numbers of
species and individuals have not significantly changed at any of our intertidal stations since 1980. Species
compositional changes have also been relatively minor at our intertidal stations, and over the baseline
period, were limited to rearrangements in the ranking of dominant species rather than additions or deletions.

INTERTIDAL CONCLUSIONS

Long-term studies of intertidal infaunal communites characterized areas communities within and
beyond areas that will be potentially impacted by the Millstone facility. These data established spatial
relationships among sampling stations, and investigated the extent and direction of temporal fluctuations
in the abundance and numbers of species that have occurred from 1980 - 1985. During this period, no
changes in intertidal communities could be attributed to operation of Millstone Units 1 and 2 or
construction of Unit 3. Data presented here appear representative of natural, undisturbed intertidal
communities and will be the basis for ail future impact studies performed during 3-unit operating conditions.

26

SUBTIDAL RESULTS
Sedimentary Environment

Quarterly mean grain size and silt/clay content of subtidal sediments from June 1979 to March
1986 are plotted in Figure 8. Sediments at subtidal stations ranged from fme to coarse sands and
contained up to 40% silt/clay. Bottom sediments at IN were composed of fine (0.125-0.25 mm) to
medium (0.26-0.50 mm) sands. Since December 1983, seven of ten quarterly values were lower than
those obtained prior to this period. At EF, sediments were composed of fine to medium sand. Coarse
sands only predominated in March 1981. Grain size at this station was relatively stable at this station
until .lune 1985; since then greater seasonal variations and a general increase in mean grain size have
occurred. Sediments at GN were generally composed of medium sands, although over the sampling
period they ranged from 0.14-0.76 mm. From March 1979 to March 1983, grain size at this station
gradually increased and since then, relatively larger seasonal peaks in grain size have been evident during
September. Sediments at JC were mostly medium sands, although coarse sands sometimes occurred
during winter months (i.e., December and March). Of all stations, JC sediments were among the
coarsest during the study.

Silt/clay content of subtidal sediments ranged from 1.3 to 44.1%. At GN, silt/clay ranged between
10% and 20% and has been relatively consistent since December 1980. At IN, silt/clay ranged from
5.5 to 44%, although 17 of the 28 values were between 5% and 10%. Since June 1983, IN sUt/clay
content increased to levels higher than those previously observed. Silt/clay values at JC ranged from 3
to 24%; however, 23 of 28 values were less than 10%. At EF, silt-clay content ranged from 2-14%,
and 26 of 28 values were between 1% and 10%.

Sedimentary characteristics of all stations, except JC, have exhibited some temporal shifts during
the study. Values for grain size at Giants Neck grain size have generally increased since 1982. This
trend is believed attributable to the increased amounts of Mytilus edulis shell found in the sediments.
This shell increases the overall weight of sediment retained by larger sieves during analysis and inflates
grain size values. At IN, higher and more variable silt/clay values have been observed since June 1983,
when construction activities (dredging and coffer dam removal) resulted in the deposition of fine material

27

_..

'■'—--,

>

~~~^-...^

/

^>

\^

/'

\

/*

^--»

,/

T:^-''

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•d.

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[

"->

\

\

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<
V

\

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UJ i

<;

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? >

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z «:_

V

° \

^

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^-^

5

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CC

~5

^

/

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o

C/1

^::''^

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f«:) AVlO/illS

(nn) 3ZIS Nivao

(>:) AVIO/niS

(Hr<) 3ZIS Nivys

<

\

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\

♦•'^

\

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1

\

z

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u.

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'<z:Z^

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o

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1

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y

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<^

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(

^■■'

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LLl

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W Avia/iiis (ni^) 3ZIS Nivyo

(=!) A>no/iiis

(rtn) 3ZIS HNna

28

at this station. Silt/clay content at EF has also become more variable following construction activities
in the area of the Unit 3 discharge cut.

General Community Composition

The 960 samples collected from the four subtidal stations from September 1979 - .June 1985 yielded
a total of 359 taxa and 193,956 individuals. On an annual basis, polychaetes and oligochaetes were the
most abundant organisms and collectively represented 77 to 91%, 88 to 92% and '58 to 96% of the
individuals at BF, GN and JC, respectively (Table 5). At IN, these groups were also abundant (23 to
82%), although arthropods were generally more abundant than oligochaetes. Arthropods usually ac-
counted for less than 10% of the individuals found at other stations. Molluscs and rhynchocoels were
common at FF, but generally represented less than 10% of the total organisms collected.

Polychaetes frequently accounted for over half of all species collected (Table 5). On an annual
basis, the number of polychaete species collected typically ranged from 60 to 75 at all but IN, where
totals generally ranged between 40 and 50 species. Arthropods were the second most numerous species
group at all stations (20 to 40 species) followed by molluscs (15 to 3p per year/station).

Quarterly total numbers of individuals and relative abundance for each major taxa collected at
subtidal stations from September 1979 to March 1986 are presented in Appendix III. Polychaete species
number and abundances were generally highest in either September or June. Although molluscs and
arthropods contributed substantially to the subtidal communities, there were no consistent seasonal trends
evidenced by these groups. In comparison to previous years, some changes in species composition were
evident during 1986. Higher numbers of arthropod species were recorded in September and December
samples at CjN and .IC than in previous years. At these stations, total species number in September
collections was also high when compared to previous years. At IN, the numbers of species in 1986
continued to increase. This trend began in 1985 after construction activities (in 1984) eliminated most
of the species in this area. In contrast, the numbers of species and individuals of all the major taxa at
E'/F were generally lower in 1986 than in the previous two years.

29

-3- a: I o

is?

o r < S - H o

H M Q, o s: ■

. -< O u J- o o

. o a: < K - H

30

Community Abundance

Mean quarterly abundance (no. /core) of subtidal communities from March 1979 - March 1986
ranged from 60 to 393 at EF, 107 to 360 at GN, 9 to 303 at IN and 106 to 633 at JC, (values are
exponentials of those presented in Fig. 9). At EF, GN and .?C, abundance was generally highest in
June or September with declines evident during colder months of December and March. This seasonal
pattern was evident at IN until June 1984 after which peaks in density occurred in September and December.

Regression analysis using abiotic factors as explanatory variables (i.e., covariates) removed 46%,
48%, 55% and 57% of the temporal variation in community abundance at EF, GN, IN, and JC,
respectively. After removing abiotic sources of variation, no significant long-term increases or decreases
in annual mean abundance (for 1980 - 1985 only) were evident. In fact, overall abundance at all stations
was relatively stable over the sampling period (Fig. 10). Inter-annual differences did occur; however,
and paired-t tests of adjusted annual mean revealed significant a < 0.05 differences at all stations. Except
at IN, these differences were generally due to the very high abundances that occurred in past years. For
example, the high density at JC in 1984, was significantly different from 1981 to 1983 and 1985.
Similarly, the high 1984 density at EF was significantly different from all previous years. In contrast,
the low density at IN in 1984 was significantly different from every other year except 1981. I^wer
density during 1981, at GN also resulted in significant differences with 1980 and 1984. In addition, the
low 1983 density was significantly different from densities in 1980, 1982, 1984 and 1985.

Numbers of Species

The mean quarterly species numbers (no. /core) at subtidal stations ranged from 5-23 at IN, 19-40
at J(^ 12-40 at GN and 13-46 at EF (Fig. 11). Species numbers were highest at EF and lowest at IN.
Seasonal patterns generally followed those of density (higher in June or September at F^F, GN and .IC
and December at IN).

Multiple regressions of species numbers accounted for 75% (EF), 63% (JC), 61% (GN) and 47%
(IN) of the temporal variation observed since 1980. At EF the model included a significant increasing
trend which persisted after removal of quantifiable sources of variation (Fig. 12). Results of paired t-tests
showed that significant inter-annual differences occurred at all stations and were frequently in years in

31

(l+x Boi) 3^03 a3d AilSN3a NV3^^

(l+X 6oi) JUOO a3d AllSN3a NV3n

(L+X Boi) 3^03 y3d AIISN3a NV3W

(l + X Bo-|) 3yoO a3d AilSN3a HVin

M

(i+xooi) 3yoD y3d sivnaiAiaNi

(i+xooi) 3yoo ysd sivnaiAiONi

-r
i

1

\

o

UJ

o

■4-'

z
o

/

< s

(i+xsoi) 3aoo y3d sivnaiAiaNi

(1+X301) 3id03 y3d SivnaiAiaNi

3yO0 y3d S3l03dS NV3W

3^03 y3d S3ID3dS NV3M

-E 2

C i

3yoa y3d S3i03ds nv3W

3yOO y3d S3l33dS NV3W

34

\

\

\

\

\
\

\

\

\,

/

o

o

/

5

o

>' '

z

o

I

C s

moo y3d S3l33dS

3aOD y3d S3l03dS

\

\
\

T'"'

i

' — > — '

Z i

t ' \ '

IJ

z

o

s \

\

\

\

/

/
/

/

z

E2
z
<

\

o

/

z

!

o

1

E fc

< <

3y03 y3d S3l03dS

3y03 y3d S3l33dS

35

which very low numbers of species were collected. The annual mean at IN in 1984 was significantly
lower than in 1^80 and 1982. At JC, the mean number of species in 1982 was significantly lower than
those in 1980, 1981, 1984 and 1985, and the low mean values obtained in 1981 and 1983, were lower
than 1984 and 1985. Only at EF did this pattern differ; 1984 and 1985 values were significantly higher
than all previous years.

Dominance

Since 1980, a composite list of all taxa present among the ten numerically abundant forms in any
samplng year, included 18, 19, 21 and 24 taxa at GN, JC, EF and IN, respectively (Table 6). Among
these, eight taxa were dominant at all stations: Thary>x ac.utus, oligochaetes, Aricidea catherlnae, Capitella
spp., Gammarus lawrencianus, Prionospio steestrupi, Leptocheims pinguis and Mediomastus amhiseta.

Over all stations and years, oligochaetes (as a group) were the most consistently dominant taxon,
accounting for 17 to 51% (EF), 1.3 to 31% (GN), 4 to 19% (IN) and 21 to 61% (.IC) of the total
individuals collected and thus had the highest BIV's (93.1-99.1%). Aricidea catherinae was also consis-
tently found among the dominants at GN, IN and .IC, where it ranked second in terms of the six-year
BIV and generally accounted for over 10% of all the individuals collected. Other taxa among the more
consistently abundant forms (i.e., BIV > 80%) were Polycirms eximius and Protodorvillea gaspeensis at
EF, Tharyx spp. at GN and Tharyx acutus at JC.

Of all communities, that of IN was the most spatially dissimilar; 29% of the taxa included among
the ten dominants collected over the last six years, were amphipods. In addition, species type was
highly variable and only oligochaetes had a BIV > 80%. Many other dominant taxa at this station
exhibited strong temporal fluctuations in abundance. For example, the relative abundance of Tellina
agilis ranged from 1-15%, Mediomastus amhiseta from 1-20%, Ampelisca verrilli from < 1-24% and
Polydora ligni from 0-19%. No other sampling station has exhibited this degree of variability.

36

Table 6. Percent contribution and Biological Index Value (BIV) of the ten numerically most abundant
taxa at Millstone subtidal stations in each year, September 1979 - June 1985.

Effluent

Oligochaeta
Polycirrus eximius
Protodorvillea gaspeensis
Aricidea catherinae
Tharyx acutus
Tellina agilis
Rhynchocoela
Tharyx spp.
Exogone he be 3
Eumidia sanguinea
Capitella spp.
Mediomastus ambiseta
Polydora caulleryi
Lumbrineris tenuis
Caulleriella spp.
Pagurus acadianus
Leptocheirus pinusuis
Ampelisca verrilli
Microphthalmus aberrans
Prionospio steenstrupi
Gammarus laurencianus

17

31

47

51

24

39

98.4

17

7

6

6

32

8

92.9

1

7

2

3

81.7

12

1

2

1

69.4

34

1

21
2

1
4

65.5
65.1

1

2

2

59.5

<1

1

4

57.9

1

1

I

54.4

1

1

3

1

<1

1

1

53.2
47.2

<1

9

<1

<1

5

46.0

<1

<1

<1

1

43.7

<1

<1

<1

2

41.3

<1

<1

1

38.9

0

<I

<1

34.9

<1

<1

<1

2

32.5

<1

<1

<1

<1

1

31.3

1

<1

<1

<1

<1

31.0

1

<1

<1

<1

<1

29.0

<1

2

<1

<1

<1

26.2

Giants Neck

Oligochaeta
Aricidea catherinae
Tharyx spp.
Tharyx acutus
Protodorvillea gaspeensis
Lumbrineris tenuis
Mediomastus ambiseta
Polycirrus eximius
Phoxoxephalus holbolli
Exogone dispar
Polydora caulleryi
Prionospio steenstrupi
Capitella spp.
Gammarus lawerencianus
Lumbrineris impat lens
Eumida sanguinea
Polydora quadrilobata
Leptochlerus pinguis

25

31

21

17 "

13

23

94.4

19

16

35

26

13

14

94.4

9

12

10

19

16

16

90.7

14

11

1

4

75.9

2

4

3

68.5

1

2

3

63.2

9

25

7

60.2

5

3

3

58.3

3

1

1
3

2

5

51.2
48.6

<1
1
1

<1

<1

<1

3

1
<1

2
<1

1

42.6
35.2
34.7

0

<1

<1

33.8

1

0

<1

32.4

<1

<1

<1

1

1

32.4

<1

<1

<1

2

<1

25.5

<1

<1

<I

<1

<1

17.6

37

Table 6 (con' t)
Intake

OligochaeCa
Arlcidea catherlnae
Phyllodoce mucosa
Capltella spp.
Tellina agllls
Exogone hebes
Tharyx acutus
Medlomastus amblseta
Splophanes bombyx
Unciola serrata
Nucula proxlma
Leptochelrus plnguls
Prionospio steenstrupi
Ampelisca abdita
Protodorvillea gaspeensls
Ampelisca verrllll
Ampelisca vadorum
Clymenella torquata
Polydora quadrllobata
Pygosplo elegans
Polydora llgnl
Gamma ru9 lawrenclanus
Sabellarla vulgaris
Crangon septemsplnosus

16

18

15

19

5

93.1

8

15

12

13

4

79.2

1

2

<1

<1

<1

70.5

13

3

<1

67.4

5

15

2

3

67.0

5

6

1

64.9

9

2

<1

2

62.8

5

1

20

5

60.1

4

6

1

57.6

<1

4

4

57.3

<1

1

5

52.1

<1

<1

1

10

17

50.0

2

2

<l

49.0

<1

<1

1

26

49.0

1

3

<1

<I

46.2

3

8

24

<1

5

45.5

<1
1

<1

2
8

8
0

45.5
41.7

<1
1

<1

2
<1

<1

0

39.9
38.9

<1

0

<1

19

1

36.1

<1

6

<1

<1

29.5

6

<1

<1

0

<1

24.3

<1

0

<1

<1

<1

22.6

Jordan Cove

Ollgochaeta
Arlcidea catherlnae
Tharyx spp.
Polycirrus exlmlus
Medlomastus amblseta
Paraplonosyllis longlclrrata
Lumbrlnerls impatlens
Lumbrlnerls tenuis
Tellina agilis

Polydora caulleryl
Rhynchocoela
Eumida sanguinea
Tharyx acutus
Capltella spp.
Pholoe mlnuta
Exogone hebes
Prionospio steenstrupi
Leptochelrus plnguls
Gammarus lawrenclanus

51

41

61

43

21

34

99.1

8

21

17

25

10

11

92.1

1

2

3

1

2

5

80.7

4

3

11

3

5

8

79.8

19

2

1

2

43

11

77.6

1

1

1

<1

<1

<1

67.5

2

1

1

<1

<1

0

55.3

2

6

2

3

4

8

52.2

<1

3

<1

<1

2

2

50.0

<1

<1

1

8

2

1

46.7

<1

1

1

I

1

1

43.9

1

2

<1

<l

<1

1

40.4

2

2

<1

2

1

1

36.8

1

1

1

2

1

3

35.5

<1

<1

1

1

<1

<1

34.2

<1

1

<1

<1

<1

1

31.1

<1

<1

1

<1

1

<1

28.9

<1

<1

<1

<1

<1

<1

26.8

<1

<1

1

<1

<1

<1

19.3

38

Species Diversity

Mean annual species diversity (H') ranged from 2.6 to 4.6 (Table 7). Low diversity indices (e.g.,
1980 at F,F and 1984 at JC) were seen when short-term pulses in species abundance caused the evenness
component of diversity to decline. High H' values reflected changes in the numbers of individuals or
species, but not in the equality of the distribution of individuals among species.

Table 7.

Annua:

1 t

Dea

n specli

3S dlverslt-

y 1

;h'),

, even.

less (J)

, spi

5Ci

Les number

(S)

and t-

ot:

Jl

Indivldi

ual co:

llecti

ed

at MlUsti

Dne subt

;idal

SI

:atloi

IS Er.

Dm

Septet

nber

1979 - .

June 1985.

Station

1980

1981

1982

1983

1984

1985

Effluent

H'

2.7

+

0.

2 3.9

+ 0.3

4.4

+

0.2

4.6

+

0.1

3.6

+

0.2

4.8

+ 0.1

J

0.4

+

0.

1 0.7

+ 0.1

0.7

+

0.1

0.7

+

0.1

0.6

+

0.1

0.7

+ 0.1

S

63

*

6

66

+ 13

63

+

9

75

+

8

84

+

4

86

+ 5

N

1583

+

29

1324

+ 364

689

-

144

809

1

88

2333

+

211

1667

+ 228

Giant Ne<

l!l

H'

3.6

+

0.

1 3.5

+ 0.2

3.4

+

0.1

3.4

+

0.1

3.5

+

0.2

4.2

+ 0.1

J

0.6

+

0.

1 0.6

+ 0.1

0.6

+

0.1

0.6

+

0.1

0.6

+

0.1

0.6

+ 0.1

S

68

+

4

57

+ 10

69

+

6

53

+

5

73

+

8

82

+ 4

N

2080

+

46

1177

+ 394

1975

1

456

1230

+

175

2549

+

217

1824

+ 281

Intake

0.1 3.8+0.1 3.9+0.1 3.4+0.3 3.4+0.2 3.8+0.3
0.1 0.7 + 0.1 0.7 + 0.1 0.7 + 0.1 0.7 + 0.1 0.7 + 0.1

445 + 335 907 + 293

Jordar

1 Co

ve

H'

3.6 + 0.2

3.7 + 0.4

3.0 + 0.4

3.0 + 0.2

2.6 + 0.2

3.8 + 0.2

J

0.7 + 0.1

0.6 + 0.1

0.6 + 0.1

0.5 + 0.1

0.4 + 0.1

0.5 + 0.1

S

66 + 1

55 + 9

44 + 5

55 + 4

67 + 9

72 + 9

N

1594 + 480

1202 + 4

724 + 145

1477 + 174

3561 + 523

1949 + 711

39

During the baseline period, evenness (J) ranged from 0.4 to 0.8, numbers of species from 30 to 86
and individuals from 301 to 3,561. Values for J were generally highest at IN and most consistent at
GN (0.6 in every year); EF and GN had the most species and IN generally the fewest. The numbers
of species collected at EF, GN and JC increased from 1982 through 1985 when high numbers of species
were collected at all stations. The IN station had consistently had lowest mean numbers of individuals
in all sampling years.

Quarterly values of species diversity from September 1979 to March 1986, for subtidal stations are
presented in Appendix IV. At all subtidal stations, H', S and J were generally highest in the September
or .June. At F.F, all diversity values in the three 1986 (September and December 1985 and March 1986)
were lower than similar periods for the last two years. Values of H' over the same period at GN were
slightly lower than 1985, but very comparable to previous years. Because of the high density of
Ampelisca spp. in the December IN collections, H' was lower than all previous observations, otherwise,
values were similar to previous years. At JC, all species diversity index components in 1986, were
similar to previous years.

Cluster Analysis

Cluster analysis, performed to examine spatial and temporal similarities among subtidal collections,
clearly illustrated the spatially distinct nature of the infaunal community found at IN (Group I), and
the strong spatial similarity among collections from EF, GN and JC (Group II) (Fig. 13). Within the
IN group (I), collections made in 1985 and 1984 separated from previous years due to a species
compositional shift. In each of the last two years, large increases in the numbers of ampeliscid arthropods
have occurred, together with a marked reduction in annelid number (particularly oligochaetes).

Group II included all other collections and the primary cluster was subdivided into station groups
(A, n, C). Within each group, collections made during 1985 and 1984 linked at highest similarity
reflecting the area-wide abundance of oligochaetes and Mediomastus amhiseta. In addition, species that
have been traditionally dominant at subtidal stations were found in unusually high abundance in these
years. For example at FF, high densities of Lumhrineri.^ tenuis, Ampelisca verrilli and l.eploc/ieirus
pinguis occurred in each of the last two years, while at GN and JC, Tharyx spp. and Polycimjs eximius
were very abundant.

40

0 -

10 -
^ 20 -

01

^ 30-
^ 40 -
§50-
^50-
70 -
80 -

\ \ W W <^ <^ ^^ '^^ <^^ <^^ -^o '^n '^c t^^ "^o^ t' % % % % % %
\ \ >> *= */ *o '*y \ \ \ \ \ \ \ */ *o \ \ \ \ \ \ \ \

Figure 13. Dendrogram resulting from classification of annual infaunal collections at Millstone subtidal stations from
September 1979 - June 1985.

SUBTIDAL DISCUSSION

I'he subtidal benthic monitoring program characterized infaunal communities inhabiting three areas
potentially impacted by power plant operations (IN, F.F and JC) and an unimpacted reference area
(GN). J'emporal and spatial changes in species abundance and overall community composition were
evident at IN and F,F and appear related to power plant to construction and related dredging. Differences
also occurred at GN and JC, but given the limited area influenced by two-unit operations, changes are
probably reflecting natural events. The following section is intended to summarize the spatial and
temporal changes observed over the monitoring period and assess whether these changes were related to
power plant operation.

During the baseline period, infaunal community abundance and species composition at IN reflected
the unique nature of this station and exhibited impacts associated with construction and dredging activities
which have occurred in the area. Prior to construction, a variety of amphipods were present at this
tidally scoured station and infaunal communities were more typical of those found in offshore areas

41

where bottom currents are higher (Biembaum 1979). After construction, the infaunal community
responded to bottom disturbances in a highly predictable manner. As in other areas subjected to
disturbance, (i.e., dredging) the initial decrease in species numbers and abundance was followed by the
rapid invasion of opportunistic species (e.g., Polydora ligni, Capitella Mediomastm amhisela), (Grasste
and Grassle 1974; McCall 1977; Swartz et al. 1980; Flint and Younk 1983; Nichols 1985). Following
these species, ampeliscid amphipods, more traditionally found at the IN station, settled and became very
abundant. These species can stabilize the sediment surface (Dlumer et al. 1970; Sanders et al. 1972)
and thus allow recolonization and recruitment of other species to the area.

Power plant related impacts at EF, even during the period immediately following construction
activities, were less dramatic than those at IN. Levels of silt/clay were only slightly elevated and
apparently enhanced colonization of species that rely on fine material as a food source. In 1985, densities
of deposit feeding species such as oligochaetes, T/iary-^ spp., Tellina agilis, Lumbrineris tenuis and
Polyc.lmis eximius remained higher than most previous years (except 1984). Although these species
were present at this station in the past, their relative abundances were much lower before construction.
The FF community also exhibited a significant increase in the average number of species. Although
relatively high numbers of species have been collected at this station, the most dramatic increase occurred
after construction. This increase probably reflected the influx of deposit-feeding species, which utilized
the higher silt/clay content found after construction began. However, since the opening of the second
discharge cut, silt/cIay content decreased and the numbers of amphipod and mollusc species increased
in the three quarters during the 1986 sampling period. Despite these changes, the structure of the FF
community has exhibited a higher degree of year-to-year similarity than that at IN.

Generally, the GN and JC communities have been more similar to each other in terms of species
composition, abundance and diversity. Species comprising these communities and their abundances are
more similar to other studies of near-shore areas (e.g., Watling 1975) than those of IN. During the
baseline period, an area-wide increase and decline was seen in the abundance of Mediamaslus amhiseta
at GN and JC. This species was the most abundant organism at both stations during 1984, and
accounted for 25% (GN) and 43% (JC) of the total organisms collected. In 1985, the relative abundance
of Mediomaslus amhiseta declined to 7% and 12% at GN and JC, respectively (lower densities of this
taxon were also evident at EF and IN in 1985). The decreased abundance of Mediomastus amhiseta at

42

JC and GN was accompanied by increases in more traditionally dominant members of these communities
(e.g., Lumbrineris tenuis, Aricidea catherinae, Polycirrus eximius)

Temporal shifts in community composition and abundance have occurred throughout the study at
all subtidal stations. This variation often reflects the interaction of biotic and abiotic factors (CouU
1985; Holland 1985; Nichols 1985) and temporal shifts in numbers of species, abundance, diversity and
species composition are characteristic of shallow-water benthic communities (Green 1969; Eagle 1975;
McCall 1977; Watling 1975; Holland and Mountford 1977; Rachor and Gerlach 1978; Loi and Wilson
1979). Even though subtidal abundances in the 1986, were lower than in recent years, regression models,
which included natural abiotic factors as variables, accounted for the lower values; thus the observed
differences were not due to plant operation. Shifts in infaunal species abundance probably reflected
variations in recruitment success and mortality, processes which are frequently linked to predation and
changes in the local physical and chemical environments (Nichols 1985; Gallagher et al. 1983). The
short-term rearrangements in the ranking of a few of the dominant species apparently reflect the effect
of these natural phenomena (Watling 1975; Flint and Younk 198.3; Nichols and Thompson 1985).

SUBTIDAL CONCLUSIONS

The Millstone subtidal benthic monitoring program detected some power plant related impacts at
stations in the immediate vicinity of the discharge (EE) and intake (IN) structures. Observed changes
occurred prior to 1985, and were attributed to Unit 3 construction activities and not to operation of
Millstone Units 1 and 2. Recent observation of community parameters at IN indicate the area is
recovering from the disturbance. The opening of the second discharge cut may have caused recent
changes in sedimentary and community parameters observed at EE. The widespread nature of infaunal
community changes at GN and JC suggest a response to naturally occurring events and are not related
to operation or construction of the Millstone facility. Data obtained during this study period will enable
us to distinguish any future impacts due to 3-unit operation of the Millstone facility from those that
occur naturally.

43

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Battelle, 1977. Benthic Program Evaluation. Prepared by John Dickinson and presented at the
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Beukema, .l.J. 1979. Biomass and species richness of the macrobenthic animals living on a tidal flat
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44

Caspers, II. 1980. The relationship of saprobial conditions to massive populations of tubificids.
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Clifford, II.T. and W. Stephenson. 1975. An introduction to numerical classification. Academic
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50

Appendix I. Quarterly number3 of species (S), number of Individuals and relative

percent (%) for each major taxon collected at Millstone Point Intercldal
stations sampled for September 1979 - March 1986.

Giants Neck

1980

Polychaeta

Ollgochaeta

Mollusca

ArChropoda

Rhynchocoela

Totals

1981

Polychaeta

Ollgochaet

Mollusca

Arthropoda

Rhynchocoe

Totals

1982

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

Totals

1983

Polychaeta

Ollgochaet

Mollusca

Arthropoda

Rhynchocoe

Totals
1984

Polychaeta 13 34 1 52

Ollgochaeta - 295 45

Mollusca

Arthropoda

Rhynchocoe

Totals 17 661 5 96 18 186 9 577

1985

Polychaeta 13 227 65 6 248 68 4 25 22 7 113

Ollgochaeta - 49 14 - 8 2 - 40 36 - 529

Mollusca

Arthropoda

Rhynchocoe

TOTALS

1986

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

Totals

5i

Polychaeta

OUgochaeca

HoUusca

Arthropoda

Rhynchocoeli

Totals

1981

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoel:

359
2447

2416
3256

214
1191

597
3307

26

2

5 185

34

948

70

324

60

379

28

2 8

1

1982

Polychaeta

Ollgochaet

Mollusca

Arthropoda

Rhynchocoe

3 479 17
- 1868 65

Totals

1983

Polychaeta

Ollgochaet

Mollusca

Arthropoda

Rhynchocoe

932

527

423
2340

477 6
7197 94

Totals

1984

Polychaeta

Ollgochaet

Hollusca

Arthropoda

Rhynchocoe

1081 63
605 35

1110
2000

206
2306

715 8
7955 91

Totals

1986

Polychaeta

Ollgochaet

Mollusca

Arthropoda

Rhynchocoe

Totals

233
1344

440 27
1210 73

52

Appendix I Ccont.)

White Point

16 370 89

1981

Polychaeta

OUgochaet

Hollusca

Arthropoda

Rhynchocoe

599 67
158 19

10 362 47

Totals

1982

Polychaeta

OUgochaet

Hollusca

Arthropoda

Rhynchocoe

295 61
175 36

802
451

Totals

1984

Polychaeta

OUgochaet

Hollusca

Arthropoda

Rhynchocoe

Totals

1985

373
123

Polychaeta

OUgochaeta

Hollusca

Arthropoda

Rhynchocoela

264
424

Totals

1986

Polychaeta

OUgochaet

MoUusca

Arthropoda

Rhynchocoe

Totals

53

Appendix II. Quarterly species diversity (H'), evenness (J) and number of species
(S) for each Millstone intertidal station sampled from September 1979
March 1986.

Giants Neck Jordan Cove White Point

1980

Sept. 79 2.30 18 0.55 2.64 18 0.63 2.00 16 0.50

Dec. 79 2.42 6 0.94 1.65 7 0.59 2.37 12 0.66

Mar. 80 1.95 6 0.75 1.58 H 0.46 1.93 9 0.61

June 80 1.07 6 0.41 0.30 10 0.09 2.55 11 0.74

1981

Sept. 80 1.56 12 0.44 2.78 28 0.58 2.45 16 0.61

Dec. 80 1.63 9 0.51 2.25 17 0.55 1.22 7 0.44

Mar. 81 2.35 6 0.91 0.62 8 0.21 1.92 4 0.96

June 81 1.30 12 0.36 1.26 8 0.42 2.44 14 0.64

1982

Sept. 81 2.49 13 0.67 2.63 12 0.73 1.22 8 0.37

Dec. 81 0.83 14 0.22 2.06 8 0.69 1.64 9 0.52

Mar. 82 0.88 10 0.27 0.17 3 0.11 0.65 6 0.25

June 82 1.77 16 0.44 1.43 14 0.37 1.33 15 0.34

1983

Sept. 82

1.62

6

0.63

2.62

26

0.56

Dec. 82

1.12

6

0.43

2.59

21

0.59

Mar. 83

1.55

6

0.60

0.94

8

0.31

June 83

0.98

7

0.35

0.58

13

0.16

1984

1.58 9 0.50

1.32 10 0.40

1.52 3 0.96

1.44 7 0,51

Sept. 83 2.22 18 0.53 1.55 21 0.35 0.85 9 0.27

Dec. 83 2.11 5 0.91 2.54 17 0.62 1.53 9 0.48

Mar. 84 3.45 18 0.83 1.04 3 0.66 1.90 8 0.63

June 84 0.97 9 0.31 0.75 8 0.25 1.45 14 0.38

1985

Sept. 84 2.43 12 0.68 2.32 22 0.52 2.71 16 0.68

Dec. 84 0.76 9 0.24 2.12 20 0.49 1.68 10 0.51

Mar. 85 1.30 5 0.56 2.15 12 0.60 1.70 6 0.66

June 85 2.20 11 0.64 2.54 29 0.52 0.85 13 0.23

1986

Sept. 85

0.21

3

0.13

2.27

23

0.50

1.49

8

0.50

Dec. 85

0.39

3

0.25

1.21

13

0.33

1.75

4

0.88

Mar. 86

3.32

10

0,98

1.76

12

0.49

1.03

5

0.44

54

Appendix III. Quarterly number of species (S) , number of Individuals (N) and

relative percent of the total (7.) for each major taxon collected
at Millstone subtidal stations from September 1979 to March 1986.

1980

Polychaeta

Ollgochaeta

Mollueca

Arthropoda

Elhynchocoela

41 1438 81

1531
393

2166
132

1847
844
106

Totals

1981

Polychaeta

Ollgochaet

Hollusca

Arthropoda

Rhynchocoe

2126
1186
227

839 58
437 30

724
234

1012
738
202
380

Totals

1982

Polychaeta

Ollgochaeta

Hollusca

Arthropoda

Rhynchocoel

523
756

411
623

951
609

49 2398
635

Totals

1983

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

639
854

489

33

35

841

49

53

1217

55

862

59

-

703

41

-

762

34

1573
636
173
232

1784
994
248

2007

72

54

2470

62

462

17

-

852

21

201

7

15

293

112

4

21

264

11

<1

-

117

1985

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

Totals

1260

39

42

1086

1288

40

-

1127

267

8

21

275

312

10

18

185

123

3

-

27

978

50

57

1235

33

647

33

-

1434

38

160

8

16

232

6

143

7

28

772

21

13

<1

-

82

2

941

101

3755

1986

Polychaeta

Ollgochaet

Hollusca

Arthropoda

Rhynchocoe

626
867
149
234

776 43
910 61

1401
262

Totals

55

Appendix III (cone.)

1980

Polychaeta

44

2978

Ollgochaeta

-

1237

MoUusca

12

lU

Arthropoda

12

74

Rhynchocoela

-

12

381
2203

1320 37 40
2131 60

1132
2240

Totals 68 4415

Polychaeta

46

2280

Ollgochaeta

-

2114

Mollusca

26

232

Arthropoda

17

150

Rhynchocoela

-

29

663
437
110

673
208
113

1982

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

969
1127

264 18 25
1171 78

463 30 37
1030 67

Totals

1983

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

1504

50

27

114

8

33

1670

1269

42

-

1211

85

-

856

1407
1285

Totals

1984

Polychaeta

OUgochaet

Mollusca

Arthropoda

Rhynchocoe

3382
920

204

1010
139

2962
624

4587
1323
289

Totals

L985

Polychaeta

Ollgochaeta

MoUusca

Arthropoda

Rhynchocoela

Totals

1986

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

Totals

3628
831
334

2081
1490
395

261

15

36

1057

1328

77

-

732

105

6

19

156

19

1

7

12

1447
1192
155

463 32 20
840 57
69 5 12

56

Appendix III. (cont.)

1980

Polychaeta

ii3

2046

Ollgochaeta

-

5i2

Holluaca

9

52

Arthropoda

U

113

Rhynchocoela

-

6

1998
957

2166
491

1847
768

Totals 63 2759

Polychaeta

49

2059

Ollgochaeta

-

698

Molluaca

14

187

Arthropoda

22

210

Rhynchocoela

-

12

459
433

724
443

1020
624

Totals 85 3166

Polychaeta

41

2738

Ollgochaeta

-

597

HolluBca

16

168

Arthropoda

24

162

Rhynchocoela

-

12

1415
649

951
508

2398
321

Polychaeta

40

1368

Ollgochaeta

-

384

Molluaca

6

15

Arthropoda

18

200

Rhynchocoela

-

6

906
232

841
221

1217
125

Polychaeta

52

2794

Ollgochaeta

-

491

MoUusca

19

133

Arthropoda

25

304

Rhynchocoela

-

11

2256
472

2007
283

2470
282

155
55

Polychaeta

44

1691

Ollgochaeta

-

505

Molluaca

7

140

Arthropoda

20

179

Rhynchocoela

~

33

Totals

71

2548

1986

Polychaeta

46

2113

Ollgochaeta

-

545

Molluaca

20

154

Arthropoda

25

470

Rhynchocoela

~

11

1607
615

978
396
114

2139
657
105
285
31

1085
426

1401
524

57

Appendix III. Cc

1980.

Polychaeta 35 368 64 23 381 76 17 113 52 20 468

Ollgochaeta - 81 14 - 66 13 - 46 21 - 123

Mollusca 8 46 8 9 28 6 7 28 13 9 69

Arthropoda 12 75 13 11 22 4 11 31 14 16 68

Rhynchocoela - 5 1 - 3 1 - 1 <1 - 5

1981

Polychaeta

Ollgochaeta

Mollusca

Arthropoda

Rhynchocoela

1982

Polychaeta 25 463 73 21 254

Ollgochaeta - 68 11 - 153

Molluaca U 46 7 8 24

Arthropoda 19 58 9 14 124

Rhynchocoela - 2 <1 - 4

Totals 55 637 43 559

Polychaeta

Oligochaet

Mollusca

Arthropoda

Rhynchocoe

1984

Polychaeta

Oligochaet

Molluaca

Arthropoda

Rhynchocoe

Totals

Polychaeta

26

210

Ollgochaeta

-

17

Mollusca

12

158

Arthropoda

17

544

Rhynchocoela

"

15

159
1447

Polychaeta

23

585

Ollgochaeta

-

45

Mollusca

12

331

Arthropoda

19

429

Rhynchocoela

-

6

201
2354

58

Appendix IV. Quartierly species diversity (H'), evenness (J) and number of species (S)
for each Millstone subtidal station sampled from September 1979 - March
1986

Effluent

Giants

Neck

Intake

Jordan Cove

H'

S J

H"

S

J

H'

<-,

H' S J

1980

Sept. 79
Dec. 79
Mar. 80
June 80

3.09 79 0.49

2.29 51 0.40

2.49 60 0.42

2.29 61 0.48

3.40 66 0.56

3.82 78 0.61

3.30 68 0.54

3.72 61 0.63

4.

,42

54

0.77

3.03

67

0.50

3.

.77

43

0.69

3.75

62

0.63

4,

,19

34

0.82

3.58

66

0.59

4,

.02

43

0.73

4.14

67

0.68

1981

Sept. 30
Dec. 80
Mar. 81
June 81

3.48 97 0.53

3.45 38 0.66

4.00 53 0.70

4.72 76 0.75

3.95 84 0.62

3.46 41 0.55

3.19 42 0.59

3.97 60 0.67

3.79 50 0.67

3.68 25 0.79

3.50 28 0.73

4,14 46 0.75

4.02 90 0.62

2.64 46 0.48

3.68 61 0.62

4.41 68 0.72

1982

Sept. 81
Dec. 81
Mar. 82
June 82

3.86 53 0.67

4.31 45 0.78

4.54 67 0.75

4.39 85 0.76

3.19 82 0.50

3.46 71 0.56

3.54 51 0.62

3.23 71 0.53

3.

,56

55

0.62

2.

,87

49

0.51

4,

.11

43

0.76

2,

.51

36

0.48

3.

,92

39

0.74

2.

,57

32

0.51

4,

.11

44

0.75

4,

.11

58

0.70

1983

Sept. 82

4.29

64

0.72

3.51

65

0.58

Dec. 82

4.73

71

0.77

3.35

47

0.60

Mar. 83

4.39

67

0.72

3.10

41

0.58

June 83

4.84

97

0.73

3.43

57

0.59

3.43 38 0.65

3.04 36 0.59

3.24 29 0.67

3.96 43 0.73

3.33 65 0.55

2.85 51 0.50

2.64 45 0.48

3.20 57 0.55

Sept

.S3

3.42

78

0.54

3.95

96

0.36

3.79

20

C.88

Dec.

83

3.87

92

0.59

3.03

61

0.28

3.18

25

0.69

Mar.

84

3.26

74

0.52

3.26

64

0.34

3.09

21

0.70

June

84

3.92

90

0.60

3.85

70

0.30

3.45

53

0.60

2.92 77 0.47

2.10 53 0.37

2.37 50 0.42

3.01 89 0.46

Sept. 84

4.51

87

0.70

4.

,25

84

0.66

4.16

56

0.72

Dec. 84

4.61

84

0.72

4,

.00

78

0.64

3.15

54

0.55

Mar. 85

4.75

75

0.76

4,

.15

72

0.67

3.54

44

0.65

June 85

5.15

100

0.77

4,

.21

93

0.64

4.44

51

0.78

3.63 96 0.55

3.65 55 0.63

3.82 61 0.64

4.29 77 0.68

Sept

.85

4.66

70

0.76

3.93

92

0.60

3.45

54

0.60

3.75

94

0.57

Dec.

85

3.92

70

0.64

3.31

73

0.62

2.04

46

0.37

3.46

66

0.57

Mar.

86

4.41

50

0.78

3.99

83

0.63

3.94

43

0.73

3.40

46

0.62

59

Contents

LOBSTER POPULATION DYNAMICS I

INTRODUCTION 1

MATERIALS AND METHODS 2

RESULTS AND DISCUSSION 6

Abundance and Catch Per Unit Effort 6

Population Characteristics 12

Size Frequencies 12

Sex Ratios 15

Reproductive Activities 16

Molting and Growth 19

Claw Loss 25

Tagging Program 26

Movement 27

Entrainment 30

Impingement 33

SUMMARY 35

CONCLUSION 36

REFERENCES CITED 37

LOBSTER POPULATION DYNAMICS

INTRODUCTION

The American lobster, Homarua americaniis, is the most valuable commercially harvested species in
I^ng Island Sound (I.,IS). Annual landings since 1977 have ranged between 600,000 and 2,000,000 pounds
with a value ranging between 1.3 and 6.2 million dollars. The landings for New London county, which
include Millstone Point, were between 28% and 45% of the total LIS catch from 1977 to 1985 (Blake
and Smith 1984; CT DEP personal communications). Fxploitation rates in LIS are high and over 90%
of marketable lobsters are newly recruited from the sublegal size class (Smith 1977; Keser et al. 1983).
Therefore the strength of the legal catch is highly dependent on the number of lobsters in the prerecruit
size class (one molt from legal size).

The lobster monitoring program at the Millstone Nuclear Power Station (MNPS) was designed to
assess the impacts of plant operations by evaluating year-to-year, seasonal, and between station changes
in selected population characteristics such as catch per unit effort, size frequencies, growth rates, sex ratios,
female size at sexual maturity, characteristics of egg-bearing females and lobster movements. L,obster larvae
enfrainment studies are also conducted to assess impacts on the larval stage of lobsters. The results of all
these studies arc often compared to other studies conducted throughout the range of the American lobster.

Potential effects of MNPS operations on the lobster population are impingement of lobsters on the
intake traveling screens, entrainment of larvae through the cooling water systems, and thermal effects of
the discharge. These power plant impacts may reduce survival of lobster larvae and juveniles or alter the
behavior of adults which may result in a decline in the local inshore fishery.

The purpose of this report is to summarize the results of the lobster population studies conducted
during 2-unit operation from 1975 to 1985. These results will be compared to data collected under 3-unit
operating conditions to assess the possible impacts on the local lobster population associated with MNPS
operations.

MATERIALS AND METHODS

The collection of information on the abundance of lobsters in the Millstone area began in February
1969, when the numbers of legal, short, and berried lobsters were recorded using catch records from a
local commercial lobsterman (Table 1).

Table 1. Summary of lobster population sampling methodology from 1969 to 1985.

Year Sample Period Sample Method Sample Stations

1969 June-Dec Commercial Catch Records Millstone, Spindle Area, Seaside,

White Rock, Bartlett Reef
a
1970-73 Feb, May, July Commercial Catch Records Seaside, Fox Island,

Sept, Dec SCUBA Surveys Bartlett Reef

Battel le Pots (6 wood/Station)

1973 Oct Monthly Surveys of Artificial Effluent, Intake, Twotree,

and Natural Habitats (SCUBA) Giants Neck, Bay Point

Battel le Pots (80 wood) Effluent, Jordan Cove,

Twotree, Intake

NUSCo Pots (60 wood) Jordan Cove, Intake, Twotree

NUSCo Pots (30 wood and 30 wire) " "

NUSCo Pots (60 wl re) "

a Single Pots set out for 1 week and checked daily.

b Pots hauled three times per week, weather permitting, from 1975 through 1985.

During the period 1970-73 lobster pot sampling was conducted daily for one week in February, May,
■July, September and December. Six wood pots were set for a week around Fox Island (at the fringe of
the Unit I plume) and, as controls, six were set around Seaside Point (1.5 miles from the plant); in May
1973 the Bartlett's Reef station was added. These pots were checked daily during the week that the Rocky
Shore surveys took place. In addition to the pot sampling, several SCUBA surveys were made annually
to assess the abundance of lobsters in these areas.

During the summer of 1973, artificial habitats consisting of an array of 36 concrete blocks (16 x 24
X 10 in), with three burrows each, were installed to provide additional habitat at four sites: outside of the
quarry-cut, in .lordan Cove, near the intake structures, and adjacent to Bartlett's Reef. Four natural

197U

Apr-Dec

1975

Jan-Oec

1975

Sept -Dec

1976-77

Jan-Dec

1978

Jan-Aug

1978

Aug -Dec

1979-80

May -Oct

1981-85

May -Oct

lobster areas were chosen for observation in conjunction with the artificial habitats: located south of the
discharge, between Twotree Island and Bartlett's Reef, near Bay Point, and south of Giants Neck. Each
artificial habitat and natural area was inspected monthly using SCUBA. These areas were monitored
through December 1975, when artificial habitat monitoring was replaced by a more intense tagging program
using pots to collect lobsters.

Beginning in September 1975, pot trawls consisting of five double entry wood pots (3-5 cm lath
spacings) strung along a 50-75 m line bouyed at both ends were used to collect lobsters. Four pot trawls
were placed at Jordan Cove, Intake, Effluent and Twotree Island (Fig. 1).

Figure 1. Location of the Millstone Nuclear Power Station (MNPS) and the three lobster sampling stations (•).

Pots were checked three times each week, rebaited with flounder carcasses and reset in the same area.
Ix)bsters > 55 mm carapace length (CL) were banded to restrain chelipeds, brought to the lab, and kept

in a tank supplied with a continuous flow of seawater. On Fridays, lobsters caught that week were
examined and the following data recorded: sex, presence of eggs (berried), carapace length (CI.), crusher
claw position, missing claws and molt stage (Aiken 1973). Lobsters were then tagged with a serially
numbered international orange sphyrion tag (Scarratt and Elson 1965; Scarratt 1970), and released at the
site of capture. Recaptured tagged lobsters, severely injured or newly molted (soft) lobsters and those <
55 mm CL were not taken to the lab but returned to the water immediately after recording the above data.

Sampling at the effluent station was discontinued in 1978, due to the difficulty in hauling and keeping
pots set properly in that area as strong currents and large boulders resulted in snagged trawls and lost
pots. From 1975 through 1978 sampling was conducted from January to December and from 1979 through
1985 during the months of highest catch: May through October. Starting in 1979, surface and bottom
water temperatures were recorded at each station. .

To obtain more information on small lobsters, wire pots (2.5 cm ) were added to the sampling design
in August 1978. Half of the wood pots at each station were replaced with wire pots which were able to
keep many of the small lobsters that were able to escape between the lath spaces of wood pots. Quantifying
the abundance and population characteristics of these smaller individuals is important since they constitute
the majority of prerecruits whose abundance largely determines the size of the legal catch. To further
increase catch, all wood pots were replaced by wire pots in 1982 after completing a study (discussed under
"Results and Discussion") to compare the performance of the two pot types.

In 1981, we began collecting additional data to determine the size at which females first become
sexually mature. The maximum outside width of the second abdominal segment of all females was
measured, to the nearest millimeter. Female size at sexual maturity was estimated by calculating the ratio
of the abdominal width to the carapace length and plotting that ratio against the carapace length (Skud
and Perkins 1969; Krouse 1973).

beginning in 1982, pots were numbered individually to determine the variability in catch among pots.
This information would provide more accurate values for catch-per-pot than an average catch-per-pot
based on the 20 pots of each sampling location. In addition to recording the number of lobsters caught
in each pot, we began counting the number of other organisms caught in pots to examine the influence
of competing species on lobster catch. Catch per unit effort (CPUE) was adjusted by covariance analysis

for the effect of soaktime (number of days between pothauls) and the catch of competing species that
significantly affected CPUE.

The size of the local lobster population was estimated during 1976-84 using the method of Jolly (1965)
as modified by Seber (1965)(NUSCo 1984, 1985). This multiple census method uses tag and recapture
data to estimate the size of the entire population at various points in time. Due to the low accuracy of
the Jolly-Seber population estimates relative to the annual CPUE values, the use of .lolly-Seber estimates
was discontinued in 1985 (see Appendix to NUSCo 1986). The annual CPUE (lobsters caught per pot)
is a reliable index of relative population abundance, is interpreted more readily than a composite estimate,
and has a reliable and well known estimate of variance.

Methods for the collection of lobsters on the intake traveling screens are described in the Fish Ecology
section of this report under Methods and Materials- Impingement.

Initially, lobster larvae were enumerated from entrainment samples as part of the ichthyoplankton
(IP) monitoring program (see Fish Ecology); however, the methods were not designed for sampling lobster
larvae. larger volumes of water must be sampled to adequately quantify lobster larvae density because
of their patchy distribution in the water column. Beginning in 1984 a special lobster larvae entrainment
study was initiated to provide better estimates of the number of lobster larvae entrained through the plant's
cooling water systems. Lobster larvae sampling was conducted during the period of their occurrence (May
through July) at Units 1 and 2 discharges. Samples were collected with a 1.0 x 6.0 m conical plankton
net of 1.0 mm mesh deployed using a gcintry system described previously (NUSCo 1978). Sample volumes
were averaged from those calculated from the readings of four General Oceanic flowmeters. Four day and
four night samples were collected weekly (1 day, 1 night on each of 4 days). Each sample was placed in
a large 1.0 mm mesh sieve and kept in tanks supplied with a continuous flow of seawater. Samples were
sorted shortly after collection in a white enamel pan and larvae were examined for movement and classified
as either alive or dead. Ix)bster larvae were also classified by stage according to the criteria established by
Ilerrick (1911) and stored in 70% ethyl alcohol.

Since some of the catch and population data collected prior to 1979 were incomplete, they do not
provide long term continuity. Therefore, in some of the following Results and Discussion sections, only

the data which provided a comparable continuum were used to describe the lobster population under
2-unit operating conditions.

RESULTS AND DISCUSSION
Abundance and Catch Per Unit Effort

Annual catch statistics for lobsters caught in pots from 1976 to 1985 are presented in Table 2. A
total of 51,717 lobsters was caught in 40,910 pothauls. Annual total catch per unit effort (CPUE) ranged
from 0.56 to 2.10 lobsters per trap. The lower CPUE values for 1976-77 correspond to data collected
with wood pots which allow smaU lobsters to escape between the 3-5 cm lath spacings.

Table 2. Catch statistics for lobsters caught in pots ' from May through October (1976-85).

Total

Number

Number

Pots

Total

Percent

Caught

Tagged

Recaptured

Hauled

CPUE

Recaptured

1976

1691

1503

188

3043

0.56

12.5

1977

1947

1773

168

3350

0.58

9.5

1978

3578

2768

521

4232

0.85

18.8

1979

5037

3732

722

4086

r.23

19.4

1980

4268

3634

522

4182

1.02

14,4

1981

5110

4246

704

4375

1.17

16.6

1982

9109

7575

1278

4340

2.10

16.9

1983

6376

5160

936

4285

1.49

18.1

1984

7587

5992

1431

4550

1.67

23.9

1985

7014

5609

1235

4467

1.57

22.2

1976-1985

51717

41992

7705

40910

1.26

18.4

60 wood pots used from 1976-77; 30 wood and 30 wire pots used from 1978-81; 60 wire pots used
from 1982-85.

Wood and wire pots used during a 3 1/2 yr gear-comparison study provided the basis for using all
wire pots in our lobster studies beginning in 1982. Monthly total and legal CPUE for wood and wire pots
are presented in Table 3. The CPUE data are proportions (no. lobsters caught/no. pots hauled) with
nonhomogeneous variances and normorma! distributions. Therefore, the nonparametric Wilcoxon 2-sample
test was used to test for equal catchability between pot types. The CPUE of legal-sized lobsters (greater
than or equal to 81 mm CL) was similar for wood and wire pots throughout the gear comparison study;
however, except for 1981, the total CPUE was significantly higher for wire pots. This, of course, was due
to greater catches of sub-legal lobsters in the wire pots.

Table 3 Monthly catch per unit effort for wood and wire pots during gear comparibilily study

Year Month Total CPUE LegaTcPUF

Wood Wire Wood Wire

f978 Aug 055 2T5 (108 n 18

Sept 0.96 1.77 0.14 0.19

Oct 0.54 1.32 0.08 0.15

Nov 0.98 1.62 0.16 0.12

1979 May 0.86 1.32 0.06 0,06
June 1.03 1.83 0.18 0.15
July 1.24 1.95 023 0 25
Aug 0.95 1.64 0.15 0.12
Sept 0.69 1.51 0.10 0.09
Oct 0.55 1.12 0.09 009

1980 M^ 079 Tio oTs 0.15
June 0.65 1.70 0.14 0 12
July 0.69 1.77 0.18 0.17
Aug 0.56 131 0.13 0.12
Sept 0.69 0.84 0.12 0.08
Oct 0.78 0.74 0.06 0.03

ml May US 134 o!o8 0.08

June 1.53 1.16 0.15 0.08

July 1.57 1.24 0.21 0.13

Aug 1.22 1.00 O.J 3 0.11

Sept 1.22 0.73 0.11 0,10

Oct 1.12 0.66 0.13 O.m
Summary of Wilcoxon 2-sample tests for equal catch regardless of pot type.

z-statistics' for total CPUE z-statistics' for legal CPUE

7, = -1.31 (p = 0.19)
7. = 0.24 (p = 0.8 1)
z = 0.65 (p = 0.52)
z= 1.63 (p = 0.10)
The 7.-statistic corresponds to the standard nonnal distribution.

A special study was initiated during 1982 to investigate the lower catch of wire pots used in 1981 and
to examine trap efficiency in relation to the construction of parlor entry funnels in wood and wire pots.
The wire pots used in the 1981 study (5 from each station) were fished with 15 newly constructed wire
pots during the 1982 sampling period. The old wire pots (used in 1981) were fished without any modifi-
cation during the first 6 weeks of the study. These old pots were then removed for 1 week to install new
parlor and entry funnels. They were then deployed as before and fished for the remainder of the study.

1978

z=-2.16 (p<0.05)

1979

z=-2.64 (p<0.01)

1980

z = -2.49 (p<0.05)

1981

z=1.36(p = 0.17)

In Figure 2, the plot of the weekly catch in the old and new wire pots shows a great disparity between
the catch efficiency in the two pot types before potheads were changed (prior to week 6). However, after
the parlor entry funnels were changed in these 2 yr old pots they fished as well as newly constructed wire
pots. These results support the observations of Spurr (1972) and Thomas (1959) further demonstrating
the sensitivity of trap efficiency to parlor head design and placement. Spurr found that the principal factor
affecting pot efficiency is parlor funnel design and Thomas found that high-rigged entry funnels deterred
escape.

Figure 2. Weekly mean number of lobsters caught with old pots (old Tunnels vs. new funnels) and new pots at all
stations during 1982.

Other factors we examined that contribute to the efficiency of lobster traps are the number of days
between pothauls (soaktime) and the influence of competing species caught in traps. The effectiveness of.
bait attracting lobsters into a trap is reduced when traps are set out for several days without rebaiting.
The bait deteriorates more rapidly in the warmer waters of summertime than in spring or fall. Accordingly,
lobstermen adjust the timing of pothauls to ensure that pots always have an ample supply of bait.
Competing species caught in traps also feed on the bait. Lobstermen alter their pothaul schedules over
the year to ensure that their traps do not become overcrowded. Generally the influence of soaktime and

competing species are more important during the summer months when water temperatures and crustacean
activity (feeding, molting, reproduction, etc.) are at a maximum.

The incidental catch of spider crabs {Libinia spp.) during 1984 and hermit crabs {Pagums spp.) and
cunner (Taulogolabrus adspersus) during 1985, had the greatest influence on lobster catch of all competing
species caught in traps (Table 4).

Table 4. Total numbers of lobsters and incidental species caught at each station from May to
October, during 1984 and 1985.

Jordan Cove

Intake

Twotree

1984

1985

1984

1985

1984

1985

Ixjbster

2657

2257

2238

1383

2692

3374

Rock crab

71

16

208

87

112

42

Jonah crab

12

2

26

1

36

29

Spider crab^

437

163

2729

1721

71

66

Hermit crab''

28

35

323

252

77

209

Blue crab

7

8

32

13

1

0

Winter flounder

,34

32

8

5

3

4

Summer flounder

24

9

27

15

9

0

Skates

2

4

6

4

■ 7

9

Oyster toadfish

38

27

37

40

1

0

Scup

3

34

23

29

1

27

Cunner

33

22

28

10

80

175

Tautog

1

16

27

118

11

116

Sea raven

7

9

11

6

2

4

Whelks

4

1

21

3

41

74

Species with significant (p<0.05) effect on CPUE in 1984.
Species with significant (p < 0.05) effect on CPUE in 1985.

Since the effects of soaktime, the incidental catch of spider crabs in 1984 and hermit crabs and cunner in
1985 significantly biased the values for lobster CPUE, we adjusted our mean monthly CPUE through
covariance analysis. Soaktime, the number of spider crabs caught in 1984 and the number of hermit crabs
and cunner caught in 1985 were used as covariates. Monthly catches (CPUE, and CPUE adjusted for
the covariates) are presented for each station for 1984 and 1985 in Table 5.

Table 5. Catch statistics for lobsters caught at each station from May to October during 1<)84-S5

1984

Number of Total number Total CPUE Total legals l^gal

Month pots hauled caught Actual Adjusted' caught CPUE

MAY

240

JUN

260

JUL

240

AUG

280

SEP

219

OCT

255

MAY

240

JUN

260

JUL

239

AUG

280

SEP

220

OCT

260

MAY

239

JUN

260

JUL

240

AUG

279

SEP

220

OCT

259

496

2.07

2.07

503

1.94

1.95

530

2.21

2.16

493

1.76

1,78

303

1.38

1.33

332

1.30
Intake

1,23

309

1.29

1.50

486

1.87

1.90

515

2.16

2.17

397

1.42

1.44

249

1.13

1.09

282

1.09
Twolrce

1.05

436

1.82

1.80

443

1.70

1,72

438

1.83

1,77

579

2.08

2.08

382

1.74

1 68

414

1.60

1. 55

0,12
(1,11

n,i8

0,12
0,11
0,06

0,08
0,14
0.15
0,08
0.09
0.05

0,35
0,23
028
0,25
0,26
0,22

CPUE values adjusted for the effects of soaktime, and the catch of spider crabs

Number of Total number
Month pots hauled caught

MAY
JUN
JUL

AUG
SEP

OCT

MAY

JUN
JUL
AUG
SEP
OCT

MAY
JUN
JUL
AUG
SEP
OCT

600
638
927

Total CPLIE
Actual Adjusted

Total icgals
caught

legal
CPUE

Jordan Cove

1.88

1,83

34

0,13

1.81

1,78

36

0,15

2.02

2,01

33

0,12

1.20

1,19

16

006

0.89

0,83

8

0,04

1,12

1,10

12

0,05

Intake

1,22

1,24

12

0,05

1,30

1.19

35

0 16

1,21

1,20

22

0,08

0,70

0.73

5

0,02

0.45

0.43

2

0,01

0.68

0.70

5

0,02

Twolrce

2.31

2.28

40

0,15

2,67

2.66

47

0,20

331

330

94

0,34

1,98

2.06

32

0,12

1,51

1,52

21

0.11

1,51

1.52

20

0.08

CPUE values adjusted for the effects of soaktime, and the catches of hermit crabs and cunner.

10

Annual catch statistics for lobsters caught in wire pots at each station from 1978 to 1985 are presented
in Table 6. The total CPUE was greatest at Twotree (range 1.15-2.52) followed by Intake (0.94-2.07) and
Jordan Cove (0.88-1.91). CPUE of legal-sized lobsters was also greatest at Twotree (0.11-0.28) followed
by Intake (0.05-0.22) and Jordan Cove (0.07-0.15). The total CPUE from Intake during 1985 was the
lowest value reported for that station since wire pots were first used in 1978. Only 20% of the 1985 catch
was taken at Intake, whereas Intake catch comprised 26-40% of the total catch from 1978 to 1984.
Dredging activities in the vicinity of the intake structures during June 1985 were responsible for the lower
Intake catch. Because dredging removes existing habitat (shelters), lobsters are displaced temporarily until
the dredged area stabilizes. After the dredged area has stabilized lobsters will probably return to the area
and catch rates at that station should increase in 1986. Effects of dredging on the benthic infaunal
community at Intake have also been documented in the Benthic Infauna section of this report.

Table 6. Catch statistics for lobsters caught in wire pots at each station from 1978 through 1985.

Number of

Total number

Total

Total legals

Legal

pots hauled

caught

CPUE

caught

CPL'E

Jordan Cove

im

349

634

1.82

34

0.10

1979

701

1337

1.91

97

0.14

1980

722

966

1.34

63

0.09

1981

724

640

0.88

51

0.07

1982

1473

2816

1.91

152

0.10

1983

1449

2368

1.63

218

0.15

1984

1494

2657

1.78

171

0.12

1985

1494

2257

1.51

139

0.09

Intake

1978

348

720

2.07

77

0.22

1979

709

1184

1.67

98

0.14

1980

721

903

1.25

60

0.08

1981

730

749

1.03

39

0.05

1982

1449

2740

1.89

153

0.11

1983

1439

1646

1.14

126

0.09

1984

1499

2238

1.49

147

0.10

1985

1474

1383

0.94

81

0.06

Twotree

1978

329

470

1.43

67

0.20

1979

641

738

1.15

72

0.11

1980

673

987

1.47

109

0.16

1981

733

847

1.16

127

0.17

1982

1418

3567

2.52

403

0.28

1983

1456

2350

1.61

308

0.21

1984

1497

2692

1.80

392

0.26

1985

1499

3374

2.25

254

0.17

Annual CPUE's and approximate 95% C.I. for wire pot data are presented in Table 7. These CPUE's
were computed as the geometric mean of the ratios of (no. lobsters) to (no. wire pots), because these
ratios are nonadditive and have an asymmetric distribution about the arithmetic mean. Therefore, the
geometric mean is the best statistic for constructing C.I.'s which should be asymmetric. Based on the
inspection of the C.I.'s in Table 7, the 1980 and 1981 CPUE's were the lowest annual values of all years
from 1978 to 1985. Conversely, the 1982 CPUE was the highest armual value when all years were
compared and was due to a strong prerecruit class in 1982 (also apparent in the 1982 frequency distribution
- see next section) which sustained record landings in 1983 and 1984 when these lobsters molted to legal
size.

Table 7. Geometric mean CPUE and approximated upper and lower 95% confidence interval.s for
lobsters caught in wire pots at all stations from 1978 through 1985.

Year

N

Lower Bound

CPUE

Upper Bound

1978

104

1.454

1.600

1,761

1979

208

1.302

1.404

1.513

1980

218

0.997

1.103

1.221

1981

220

0.839

0.904

0.974

1982

220

1.925

2.006

2.089

1983

218

1.250

1.331

1.417

1984

225

1.540

1.607 •

1.677

1985

221

1.252

1.352

1.460

Population Characteristics

Size Frequencies

Annual size frequency distributions for male and female lobsters caught in wire pots from 1979 to
1985 are shown in Figure 3 and for each station in Figure 4. Population statistics for lobsters caught from
1976 to 1985 are summarized in Table 8. Annual mean CL's have been consistent since lobsters have
been collected using pots. The mean CL of lobsters caught in wood pots was greater (range 73.3-76.6)
than the mean CL of lobsters caught in wire pots (range 70.8-71.8).

12

FEMALES

SO 75 50 75 50 75 50 75 50 75

CARAPACE LENGTH (MM)

50 75 50 75

Figure 3. Size frequency distributions for male and female lobsters caught at all stations from 1979 through 1985.

An important objective of this study was to gather information on as large a segment of the local

2
lobster population as possible. Through the use of wire pots (2.5 cip mesh) we anticipated increased

catch of smaller sized lobsters capable of escaping through the 3-5 cm gap between the laths of the

commercial wood pots. A Kolmogorov-Smimov test on the size frequency distributions of lobsters caught

in the two pot types indicated that wire pots caught significantly (p < 0.05) more of the size class smaller

than 75 mm CL than did wood pots. These results are similar to those of Krouse (1973) who found that

the CL of the catch from wire pots averaged between 67.9 and 70.5 mm. lie considered the modal size

of his catch (70 mm CL) to be the size at which lobsters are less apt to escape the traps; using the same

reasoning, lobsters in our study were vulnerable to the wire pots at 70 mm CL and to the wood pots at

about 76 mm CL. Knowledge of lobsters in the 70-76 mm size class is important, since these individuals

constitute a large proportion of the prerecruits (i.e., those individuals within one molt of legal size). Since

the lobster population of the Millstone Point region is subjected to a high exploitation rate (Keser et al.

1983), the size of the legal catch is largely determined by the abundance of the prerecruit size class the

year before. The sensitivity of our sampling effort in defming year class strength was apparent in 1982.

As stated in the previous section, during 1982, we observed a very strong prerecruit class (Fig. 3); when

these individuals molted the following year, record landings were realized throughout LIS in 1983 and

1984 (CT DEP Marine Fisheries Statistics).

13

2b

JORDAN COVE

00

MALES

1

J

75-

/

11 iiii

i

J

50-

i k

1 A A

i

i

25

i.i^

U^

1

j^

25

f ^

*f f

?

?

50

Fl

f r

T

75-

FEMALES

00-

1979 1980

1931 1982 1983

1 984

1 985

75-

50 75 50 75

50 75 50 75 50 75 50 75 50 75 100

CARAPACE LENGTH (MM)

FEMALES

1979 1980 1981 1982 1983

50 75 SO 75 50 75 SO 75 50 75 50 75 50 75 100
CARAPACE LENGTH (MM)

TWOTREE

50 75 50 75 50

75 SO 75 SO 75 SO 75 50 75 100

CARAPACE LENGTH (MM)

Figure 4. Size frequency distributions for male and female lobsters caught at each station from 1979 through 1985.

14

Table 8. Population statistics for lobsters caught in wood and wire pots from 1976 to 1985.

WOOD

WIRE

N*

Mean CL

Percent

N'

Mean CL

Percent

+ 1 S.D.

Legals

± 1 S.D.

Legals

1976

596

73.6 * 7.0

13.6

1977

549

76.6 ♦ 6.6

15.7

1978

777

75.1 ± 5.6

14.2

1910

71.5 * 6.5

8.5

1979

1510

75.7 ± 5.6

15.4

2846

71.2 * 7.0

8.2

1980

1213

75.9 ± 5.8

18 1

2529

70.9 ♦ 6.6

7.2

1981

2423

73.3 ♦ 6.0

10,4

1983

71.0 ± 7.5

9.6

19S2

7839

70.8 ± 6.9

6.3

198?

5435

71.7 t 7.3

10.1

1984

6156

71.8 ♦ 7.1

9.6

1985

5723

71.3 t 6.7

6.6

Recaptures not included

Sex Ratios

Since 1975, the overall sex ratio of males to females was close to 1:1 (Table 9). However, when three
stations were compared, Twotree had consistently higher proportions of females, whereas Intake and
Jordan ("ove had slightly more males. Sex ratios close to 1:1 were also reported by other researchers
working in waters close to shore (Herrick 1911; Templeman 1936; Ennis 1971, 1974; Stewart 1972; Krouse
1973; Thomas 1973; Cooper et al. 1975; Briggs and Mushacke 1980). Smith (1977) found male to female
ratios of the commercial catch ranging from 1:1.06 to 1:1.81 in four different areas of LIS which agrees
with the ratios of our Twotree station which is 1.5 km offshore. Ennis (1980) indicated that sex ratios are
dependent on the size composition of the catch which in turn is dependent on the method and depth of
sampling. Ratios close to 1:1 occur up to the size at which females are sexually mature, after which
females tend to predominate in the catch due to variation in trapping behavior related to molting and
reproduction, legal restrictions of taking egg-bearing females, and the fact that mature females molt less
frequently than males (Skud and Perkins 1969; Cooper et al. 1975; Ermis 1980).

Table 9 Male to female sex ratios of lobsters caught at each station from 1975 to 1985

Jordan Cove

Intake

Twotn

1975

1.0 0.71

1976

1.0 : 0.76

1977

1.0 : 0.75

1978

1.0 : 0.75

1979

1.0 : 0.70

1980

1.0 : 0.68

1981

1.0 : 0.65

1982

1.0 : 0.62

1983

10 ; 0.70

1 984

1.0 : 0.60

1985

1.0 : 0.70

0.86

i.n

1.55

0.97

1.0

1.83

0.89

1.0

1.27

0.95

1.0

1.13

0.87

1.0

1.13

0.87

1.0

1.18

0.68

1.0

1.13

0.66

1.0

1.13

0.65

1.0

1.28

0.68

1.0

1.27

0.66

1.0

1.38

15

Reproductive Activities

Tlie presence of external eggs indicates that females are mature and the size at onset of maturity can
be determined from the size distribution of berried females. Another method of determining female size
at sexual maturity was described initially by Templeman (1935) who observed that the relative width of
the second abdominal segment of females increased with the approach of sexual maturity. In our study
wc measured the second abdominal segment widths of all females, calculated the ratio of the abdominal
width to the carapace length, and plotted that ratio against the carapace length (Skud and Perkins 1969;
Krouse 1973).

The morphometric relationship between carapace length and abdominal width for data collected from
1981 to 1985 is described in Figure 5.

o.ao

All females are

...re

0.75

_„-'

":^\

0.70

Fe.

ies begin to mature _,-''

<^"'

-'"' \

0.65

--'V'^^''

0.60

0.55

___----r''' '-•''

30 40 50 60 70 80 90 100 110 120

CARAPACE LENGTH (MMj

Figure 5. Morphometric relationship between the ratio abdominal width/carapace length and the carapace length for
data collected from 1981 to 1985 for female lobsters.
(*) mean value for each 5 mm size; ( ) y = a + bx + cx +dx ; ( ) upper and lower 95% C.I.

The carapace length and abdomen width increase in size proportionately up to the size at which females
begin to mature (about 50 mm CL for our area) after which the abdomen increases in width faster than
the carapace increases in length. When all females are mature (about 95 mm CL) the relationship between
the carapace length and the abdominal width is again proportional. In western LIS, females begin to

16

mature at about 60 mm CL and most are mature at about 80 mm CL (Briggs and Mushacke 1979). In
contrast, outside of LIS, females begin to mature at sizes substantially larger than in our area. In northern
areas low water temperatures retard reproductive maturation, whereas warmer summer water temperatures
of LIS favor early maturation of females (Smith 1977; Aiken and Waddy 1980).

Berried females have comprised between 3.1 and 6.7% of all females caught from 1975 to 1985.
Females predominate at Twotree and greater proportions of berried females were caught there (5.1-10.1%)
when compared to Jordan Cove (1.0-4.5%) and Intake (1.1-4.3%) (Table 10).

Table 10. Percentage of berried females at each station and mean carapace lengths from 1975 to 1985.

Jordan Cove

Intake

Twotree

N'

Length
Range (mm)

Length
Meant 1 SD

1975

4.5

3.5

9.7

7

73 - 84

79.1 ± 3.7

1976

2.0

3.3

11.2

16

70 - 102

82.9 ± 7.7

1977

1.4

3.5

6.2

35

68 - 92

79.7 ± 6.4

1978

1.4

2.5

5.1

58

74- 88

80.1 ± 4.0

1979

1.9

2.7

6.2

67

64 - 93

80.6 t 5.4

1980

3.4

1.8

5.4

71

72 - 93

79.2 ± 5.1

1981

1.8

2.7

6.9

82

70 - 97

81.2 * 6.1

1982

1.0

1.1

6.2

108

64 - 99

80.0 ± 5.8

1983

2.5

3.6

8.3

123

66 - 103

80.5 ± 5,9

1984

4.3

3.3

10. 1

173

62 - 95

79.1 ± 5.8

1985

3.5

4.3

8.0

17!

63 - 94

77.0 ± 5.4

Recaptures not included

The size distribution (range, mean CL) of berried females collected have provided further evidence for the
small size at which females become mature in LIS (Table 10). The smallest berried females collected
(62-64 mim CL) were between 54-56 mm CL when oviposition first occurred assuming 14% growth per
molt. This confirms our carapace length/abdominal width relationship and suggests that 50 mm CL is
the size at which females begin to sexually mature in LIS.

The fact that females mature at a small size in LIS and that over half of the berried females are
sublegal size is important because these individuals are able to spawn before growing to marketable size
(Fig. 6).

17

CARAPACE LENGTH (MM)

Figure 6. Size frequency distribution for berried Temales caught from 1979 to 1985. Numbers in parentheses
represent the percentages of subiegal and legal berried females (%sublegal, %legal).

In comparison, females in northern and offshore populations (Maine, Canada) begin to mature at sizes
close to the legal size and only a small percentage is able to spawn prior to reaching marketable size
(Aiken and Waddy 1980).

To provide more information about the reproductive cycle of lobsters in our area, we recorded both
the fullness, and the developmental stage of egg masses carried by berried females during 1984-85 (Table
11). Based on embryo development, we concluded that berried females caught in May and June carried
eggs that were ready to hatch. The smaU number of berried females caught in .luly indicated the completion
of the biennial spawning cycle. Females that were fertilized in the previous year began extruding eggs in
August and the number of berried females caught carrying newly extruded eggs peaked in September and
October. About 89% of the berried females examined in 1984 for egg mass fullness had 1/2 or more the
normal complement of eggs and, in 1985, 86% had 1/2 or more the normal complement. Only 3.7% of
the berried females in 1984 and, in 1985, 7.7% had less than 1/4 the normal complement of eggs. This
may be compared to 10-14% of the berried females in western LIS carrying abnormally low numbers of
eggs in 1976 (Smith 1977). Smith's concern was that such an additional source of natural mortality (i.e.,
abnormally low fecundity) in western LIS, an area where 30% of the females are berried, could affect the
entire Connecticut fishery.

Table 1 1 The number of berried females examined for egg mass fullness and egg development
from May to October during 1984-85.

Number with Number with Number with Number with

Number of
Month Berried Females

Complement Complement Complement

Number with

Full Developmental

Complement Stage

MAY

JUN
JUL
AUG

It Green with
optical disks

SEP
OCT

48
5(1

1
1

5
5

16

7

10
16

16
21

TOTAL

164

6

12

30

43

73

1985

MAY

JUN
JUL
AUG

It. Green with
optical disks

SEP

56

2

3

4

14

33

OCT

89

4

6

3

23

48

10TAL

222

17

IS

21

52

117

Molting and Growth

Ix^bster growth was determined from carapace length measurements for those lobsters that molted
between tagging and recapture. The number of molting lobsters observed in the weekly catch varied from
year to year and over the sampling period (Fig. 7). In general, molting peaked in June although in several
years a fall molting peak was also observed. Frequency of molting and size increase per molt are reported
to be affected by temperature, light, nutrition, social behavior, injury/regeneration, habitat, season of year
and reproductive development (Aiken and Waddy 1980). The fact that secondary molts were observed in
our study area is not unusual; two molting peaks were observed by Lund et al. (1973) for LIS and by
Russell et al. (1978) for Narragansett Bay.

Several researchers have shown that growth increment per molt in crustaceans is best described by
linear regression (Wilder 1953; Kurata 1962; Mauchline 1976). Carapace lengths at recapture (post-molt
size) were regressed on carapace lengths at tagging (pre-molt size) for data collected from 1978 to 1985.
Regression plots, equations and growth parameters for all lobsters (n=733) and males (n = 296) and
females (n = 437) are presented in Figure 8.

19

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

MONTH

50

1973

40

_,.-'-,

g

30

/

\ /

^^^^

\

o

1

\

■z
■z.

20
10
0'

y

>

4

•\

^

/

/ V

h

AA

V

\

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTH

bO

1979

40

/•''

in

fT-

"^

r-'

"■y

g

X^

1,

r

o

UJ

m

20

-*

2
-I

N-A

^

10

0-

-^

\ V

V

vv^

^A

UAY JUN JUL AUG SEP OCT NOV

MONTH

Figure 7. The number of molting lobsters ( ) and bottom water temperature ( ) from 1977 to 1985.

20

MAY JUN JUL AUG SEP

MONTH

OCT NOV

1982

Fig. 7. cont.

UAY JUN JUL

AUG

MONTH

SEP OCT Haj

^,5 ?\

-J- 0

21

50-

1985

C/1

♦0-

^,-

,-'---'

'

'-.^^

lb

'

^v

m

3

30

,'^'

'

U-
O

t

%

\

m

20-
,0^

^

h

\

V

v^

WAY JUN

Fig. 7. cont.

AUG

MONTH

22

ALL LOBSTERS

New -y.ze = 1 5.797 + (0.895) Old S

CARAPACE LENGTH AT TAGGING (MM)

50 60 70 80 90 100 110

CARAPACE LENGTH AT TAGGING (MM)

110-

FEMALES

^

New s:z« -

■ 3.447 + (0.923) Old Size

>

r-=0.7a

2^

100

,' .

EC

/' /

30 1

. y / /'

in

y

•• •y' - y

mi-

yr....y

T

ii

y^.::liv:

.;'■

m

. /■■.•.yf..:-y

70-

hi

.y....f'

<

CARAPACE LENGTH AT TAGGING (MM)

Figure 8. Linear regressions for carapace lengths at tagging and recapture Tor all lobsters, males and females for data
collected from 1978 through 1985. ( ) y = a + bx; (- - -) upper and lower 95% C.I.

23

Growth of males and females was significantly different based on t-tests of y-intercepts and slopes (p
> 0.05). Smaller-sized males ( < 60 mm CL) had a greater incremental size increase when compared to
females of the same size (Fig. 9).

CARAPACE LENGTH (UM)

A

FEMALES

v'

CARAPACE LENGTH (UU)

CARAPACE LENGTH (UU)

Figure 9. Mean incremental size increase for all lobsters, males and females from tag and recapture data collected
from 1978 through 1985 (vertical bars = 2 standard deviations).

24

Lx)wer incremental size increases for females smaller than 60 mm (CL) are expected since females begin
to sexually mature at about 50 mm. Energy that would otherwise have been used in carapace growth was
diverted to widening of the abdominal segments and development of the ovaries. The average growth per
molt for males (14.1%) and females (13.7%) was similar to results reported by Briggs and Mushacke
(1984) for western LIS lobsters (males 14.5%; females 12.5%). Cooper and Uzmann (1980) reported
higher growth increments for the offshore lobster population, 18.7% for males and 16.7% for females.
They attributed the lower growth of the inshore population to lobster inactivity during the colder months
of the year.

Claw Loss

The percentage of lobsters missing one or both claws (culls) ranged from 9.0 to 17.4% for lobsters
caught in wood pots and 10.6 to 15.5% for lobsters caught in wire pots (Table 12).

Table 12. Claw loss for lobsters caught in wood and wire pots from 1975 to 1985.

Percent Cull

Percent

Missing

Percent

Missing

One Claw

Two Claws

Year

Wood

Wire

Wood

Wire

Wood

Wire

1975

9,n

7.8

1.3

1976

15.4

-

13.5

2.0

1977

11.6

-

10.4

1.2

1978

15-9

149

14.1

14.0

19

0.9

1979

17.4

15.5

15.0

14.4

2.5

12

1980

17.0

13.6

14.8

12.2

2.2

1.5

1981

143

12.0

13.0

11.1

1.3

1.0

1982

11.1

-

10.4

0,7

1083

12.4

11.6

0.8

1^84

10.6

9.8

0,7

1985

-

11.1

10.4

n.7

These percentages are typical for LIS; Smith (1977) reported 26.4% claw loss in LIS east of the Connecticut
River and Briggs and Mushacke (1979) reported claw loss varying between 7.4 and 22.8% in western LIS.
In general, the proportion of culls at each station was similar, and lobsters with missing or damaged claws
were observed more frequently after the spring and fall molts. Pecci et al. (1978) reported that trap-related
injuries resulting in claw loss are often associated with water temperature, fishing pressure (i.e., handling
by lobstermen), trap soaktime, and physical condition of the lobster (i.e., its nearness to molting).

25

Tagging Program

From 1975 to 1985, 57,359 lobsters were caught; 47,259 were tagged and released, and 8,053 (17%)
subsequently were recaptured in our sampling program (Table 13).

Table 13. Summary of tag and recapture studies from 1975 through 1985.

NUSCo

Commercial

No.

Mean CL

Returns

Mean CL

Returns

Mean CL

Year

tagged

(mm)

No.

Pet.

(mm)

No.

Pet

(mm)

1975

2285

67.3

123

5.4

a

116

5,1

80,2

1976

2963

75.5

351

11.9

'

515

17.4

79.6

1977

2870

74.5

240

8.4

"

311

10.8

79.3

1978

3193

73.6

508

15.9

75,5

884

27.7

81.1

1979

3732

72.8

722

19.4

75.1

1776

47.6

77.5

1980

3634

75.5

522

14.4

75.7

1363

37.5

76.4

1981

4246

72.4

707

16.7

74.8

1484

35.0

76.3

1982

7575

70.9

1278

16.9

73.2

2518

33.2

75.5

1983

5160

71.8

936

18.1

73.6

2266

43.9

76.9

1984

5992

71.9

1431

23.9

73.0

1.262

21.1

78.7

1985

5609

71.3

1235

22.0

73.1

899

16.0

•78.3

Recaptures not measured.

Commercial lobstermen caught an additional 13,394 (28.3%) of our tagged lobsters over the same period.
In recent years (1984-85), the percentage of tagged lobsters caught by commercial lobstermen was lower
(18.6%) than rates of recapture from 1975 to 1983 (30.6%). Conversely, our rates of recapture during
1984-85 were higher (23.0%) than rates during 1975-83 (15.1%). This disparity in rates of recapture was
due to the implementation of the escape vent regulation in April 1984 (Landers and Blake 1985). The
escape vent (1 3/4 in x 6 in) allows the escape of sublegal sized lobsters and, since the majority of our
tagged lobsters are sublegals, fewer were retained in the commercial traps with the required vents. In
comparison, our traps do not contain escape vents and retain greater numbers of tagged sublegals.

Additional evidence for the effectiveness of escape vents was apparent in the mean size of tagged
lobsters caught in commercial gear before (1975-83) and after implementing the escape vent regulation in

26

1984-85. The mean CL of tagged lobsters caught in commercial gear prior to the escape vent regulation
was 76.5 mm and was significantly smaller (t-test p<0.01) than the mean CL of 78.6 mm for tagged
lobsters caught with the regulation in force. Krouse and Thomas (1975) calculated selectivity curves for
lobsters caught in traps with various vent sizes (1 1/2, 1 5/8, 1 3/4 in). Traps fitted with a 1 3/4 in escape
vent had 50% retention of lobsters ranging in size from 75.4-78.8 mm CL. The mean CL of lobsters
caught in our wire traps since 1978 ranged between 70.8 and 71.8 mm and was lower than the 50%
retention sizes reported by Krouse and Thomas (1975). Thus, most of our tagged lobsters are able to
escape from vented commercial traps thereby decreasing the probability of their recapture in commercial
traps and increasing the proportions captured by unvented pots.

Movement

Because lobsters were tagged and released at the station where captured, any migrations from the
capture area could be detected at recapture. Recapture data from our sampling efforts and those of
commercial lobstermen were used to assess movement patterns.

About 95% of the lobsters were recaptured at the release station with movements between stations
being minimal. Of the exchanges that did occur, most were between Jordan Cove and Intake. During
1976-77, when sampling was conducted at the Effluent station, only 58% of the lobsters released there
were subsequently recaptured there. Thirty percent moved to Jordan Cove, 9% moved to the Intake
station and 2.5% moved to Twotree. TTiis suggests that lobsters may visit the effluent area to feed since
it is a productive area for mussels and other benthic invertebrates.

Tagging studies conducted in coastal waters of eastern North America indicate localized lobster
movement (Templeman 1935, 1940; Wilder and Murray 1958; Wilder 1963; Cooper 1970; Stewart 1972;
Cooper et al. 1975; Fogarty et al. 1980; Krouse 1980, 1981; Stasko and Campbell 1980; Ennis 1984). In
our studies 91% of the commercial recaptures occurred within the study area (Fig. 10, <8 km from
MNPS). Of the lobsters recaptured outside the study area, most moved to the east (97%; Fig. 11). Lund
et al. (1973) reported similar results for tagging studies in LIS. A few lobsters (n= 13) traveled considerable
distances where they were caught on the edge of the continental shelf (Figure 12).

27

Figure 10. Locations and numbers of tags returned by lobstermen in the Millstone area. An additional 3,014 tags
returned with inaccurate recapture points were reported as being caught around Millstone Point.

Figure II. l,ocations and numbers of tags returned by lobstermen in Long Island and Block Island Sounds.

28

Figure 1 2. Locations and numbers of tags returned from outside of Long Island Sound.

Other researchers working in waters off New England and on the continental shelf demonstrated similar
exchanges between the inshore and offshore populations (Saila and Flowers 1968; Uzmann et al. 1977;
Fogarty et al. 1980). Judging from the number of returns from the Race area, it is believed that these
lobsters leave the Sound through that deep water channel southwest of Fishers Island. Once out of the
Sound lobsters would have moved southerly toward the deep water canyons (Block and Hudson) or
easterly (Point Judith, RI, Buzzards Bay, MA, Martha's Vineyard and Nantucket Sounds). Recent work
by Campbell and Stasko (1985) off southwestern Nova Scotia revealed that mature male and female
lobsters ( > 95 mm CL) moved greater distances than immature lobsters ( < 95 mm CL). This hypothesis
is difficult to assess from our study results since exploitation rates are very high and most of the legal
lobsters tagged are caught by lobstermen shortly after release. However, 6 of the 7 lobsters caught at
Hudson Canyon were legal-sized and at Block Canyon all 3 were legal-sized.

29

Entrainment

lobster larvae were found in ichthyoplankton (IP) samples of the cooling water at Units 1 and 2
discharges from 1977 to 1985. Because lobster larvae distribution in the water column is patchy, large
volumes of water must be sampled to collect them. Thus, begirming in 1984, we initiated a special lobster
larvae entrainment study, these samples filter much larger volumes of cooling water (4000 m ) than do
the IP samples (400 m''). This sampling effort, focusing on lobster larvae in the cooling waters was initiated
in anticipation of Unit 3 start-up.

The timing of lobster larvae collected in entrainment samples corresponded to the developmental stage
of egg masses carried by berried females. In May, the number of berried females collected in traps was
high and the development of the eggs indicated that hatching was imminent. In June, the number of
berried females carrying ripe eggs declined and by July the low number of berried females caught indicated
the completion of the biennial spawning cycle. Although the hatching process and stage duration is
temperature dependent (Templeman 1936) and most intense at temperatures of about 20 "C (Hughes and
Mattheissen 1962), the larval phase is completed in 25-35 d under normal conditions. In general, since
1977, larvae were collected from mid-May through late-June.

Scarratt (1964, 1973) provided estimates of lobster larvae survival between stage I and IV for a
Canadian lobster population. In our study, most of the larvae collected were Stage I and presumably
hatched nearby (Table 14; 88% in 1984; 87% in 1985).

Table 14. Summary of 1984 and 1985 lobster larvae entrainment studies

1984

1985

Day

NiRht

Total

Day

Nif^ht

Total

No samples collected;

64

58

122

46

47

93

No. samples with larvae:

11

16

27

11

23

34

Number of Larvae

Stage I

15

73

88

56

69

125

Stage 11

0

1

1

0

1

1

Stage III

0

1

1

3

2

5

Stage IV

1

11

12

2

10

12

Total

16

86

102

61

82

143

30

Larval survival was not calculated due to the low occurence of Stage II and III larvae relative to Stage IV
which may have been an influx from more distant hatching. Lund and Stewart (1970) indicated that larvae
produced from the western LIS population are responsible for the gradual recruitment of fourth and fifth
stage lobsters in middle and eastern LIS. Their hypothesis appears to be true given the number of fourth
stage larvae collected in our entrainment studies.

Survival of lobster larvae after passing through the plant's cooling water system was observed in both
entrainment study years. In 1984, 2 stage IV, and in 1985, 2 stage I and 1 stage IV survived after passing
through the plant indicating that entrainment mortality is lower than the assumed 100%. Similar fmdings
at other power stations have been reported. CoUings et al. (1981) reported 14% survival for lobster larvae
(Stage II) collected at the Canal Electric Company, Sandwich, MA.

In both of the lobster larvae entrainment studies (1984-85), and the IP samples collected since 1977,
more larvae were collected in night samples than in day samples (Table 14). While this may appear at
first to contradict the photo positive behavior of lobster larvae observed by many researchers (Fogarty
1983), a combination of factors may explain the contradiction. Diurnal vertical distribution is apparently
related to light intensity, and larvae tend to disperse from surface waters during night except under bright
moonlight (Templeman 1939). The fact that more larvae were collected at night when surface densities
have been reported to be lowest may result from a combination of this lobster larvae behavior and the
intake structure design. The intake structures have curtain walls which extend down into the water column
about 2 m below MLW. This means that cooling water is drawn from well below the surface. Therefore,
since lobster larvae disperse from surface waters during darkness, they are more susceptible to entrainment
at night regardless of tidal stage.

Two 24 h samplings were conducted in 1985 to substantiate our initial fmdings of higher larval
densities in night samples and to determine peak diurnal abundance of lobster larvae in the cooling waters.
The numbers of larvae found on the two sampling dates were not significantly different; 19 larvae were
collected on 28 May and 17 were collected on 4 June (Table 15).

31

Table 15. Summary of 1985 24-hour lobster larvae entrainment studies.

Time of Day

28 May
no. larvae collected

4 June
no. larvae collected

0800

0

0900

0

0

1000

0

0

IIOO

0 Low

1120

0 High 1104

1200

0

1

1300

0

0

1400

0

1

1500

0

0

1600

0

0

1700

0 High

1719

1 Low 1709

1800

0

0

1900

0

0

2000

1'

1

2100

3

0

2200

3

2"

2300

1 Low

2357

4 High 2316

2400

0

5

0100

3

0

0200

1

1

0300

0

1

0400

1

0

0500

2 High

0540

■ 0

0600

4

0 Low 0605

0700

0

0

0800

0

Total

19

17

One larva collected alive.
One stage 11

The numbers of larvae collected in night samples (27) was significantly higher than the numbers collected
in day samples (*)) confinning our 1984 observations. The two 24 h collections were conducted 1 wk
apart to examine the effect of tide on lobster larvae entrainment under different day-night conditions.
Results indicated that lobster larvae entrainment was not significantly influenced by tidal stage.

Lobster larvae entrainment estimates from our IP program 1977-85 and from the 1984-85 lobster
larvae studies are presented in Table 16. The estimates were calculated by summing the volumes of all
samples collected over the study period, dividing that volume into the total cooling water volume over
the same period and multiplying that proportion by the number of larvae collected over the hatching

32

season. The low numbers of larvae collected, and the low entrainment estimate for IP entrainment samples
in 1984-85 compared to the special lobster larvae samples in those years, supports the need to apply the
new sampling methodology for the assessment of lobster larvae entrainment losses under 3-unit operating
conditions, given the reductions in IP sampling effort in 1983 and 1985.

Table 16. Summary of entrainment estimates for lobster larvae collected in ichthyoplankton
samples 1977-85 and in 1984-85 lobster larvae entrainment studies.

Year

Dates
Found

Total Volume (m^
Number Collected of samples collected
(number samples) May-Aug (xlO )

Total U-l + U.2^
Volume (mV
May-Aug (xlO*)

Entrainment
estimate
May-Aug

Ichthyoplankton Samples

1977

8Jun-6Jul

19 (10)

0.125

517.9

78,721

1978

5Jun-10Aug

74 (24)

0.121

662.9

405,410

1979

llJun-llJul

60(17)

0.151

467.5

185,762

1980

29May-3Jul

37 (14)

0.133

534.8

148,780

1981

27May-13Jul

18 (13)

0.138

556.3

72,561

1982

lJun-28Jul

45 (26)

0.128

677.9

238,324

1983

3IMay-20Jul

9(8)

0.060

516.0

77,400

1984

22May-19Jun

2(2)

0.060

538.0

17,933

1985

15May-10Jul

4(4)

0.036''

388.7^

43,189"

Lobster Larvae Samples

1984

21May-IOJul

102 (27)

0.505

538.0

108,665

1985

15May-29Jul

143 (34)

0.371

388.r=

149,822'=

' U-l = Millstone Station Unit 1; U-2 = Millstone Station Unit 2

Total volume (ra ) of entrainment samples sorted for lobster larvae from May through July.
*= May through July.

Impingement

Annual impingement estimates for lobsters collected on Unit 1 and 2 traveling screens from 1975 to
1985 are presented in Table 17. In general, impingement of lobsters is highest during the summer months
and coincides with peak catch in traps (NUSCo 1982, 1983, 1984, 1985, 1986). The number of lobsters
impinged at Units 1 and 2 was highest in 1982, corresponding with the highest annual catch. Impingement
of lobsters and other species is also closely related to plant operations. When units are down for scheduled
refueling or maintenance, cooling water demands are considerably less than at full power. Thus the
disparity in impingement estimates between units and over years and the lack of correspondence with trap
catch values with the exception of 1982 is related to cooling water demands.

33

Jnit 2

Both Units

56

790

663

1142

310

550

261

506

426

749

405

773

1009

1674

1041

1979

497

1496

1220

1220

480

480

Table 17. Annual impingement estimates ' for lobster collected at Units 1 and 2 from 1975 to 1985,

Unit 1

1975 734

1976 479

1977 240

1978 245

1979 323

1980 368

1981 665

1982 938

1983 999

1984 b

1985 b
Total 4991 6368 11359

' Values for the 1975-76 estimates are based on 7 days of sampling per week. The 1977-83 values are
based on 3 days of sampling per week and are extrapolated based on flow rates to represent the estimated
total number impinged.
Unit 1 sluiceway began operating December 1983.

The mean sizes of lobsters impinged during the period 1975-85 have ranged from 48.6 to 64.9 mm
CI, and were smaller than the trap catch values (NUSCo 1982, 1983, 1984, 1985, 1986). Smaller lobsters
may enter the screen house through the course bar racks more readily than larger lobsters which are seldom
impinged. Since 1982, when we began recording the sex of impinged lobsters, male to female ratios ranged
from 1.0:0.47 to 1.0:0.58 and were similar to those reported for the inshore Jordan ("ove and Intake
stations (NUSCo 1982, 1983, 1984, 1985, 1986). The percentage of culled lobsters was always greater in
impingement samples (30-50%) when compared to trap catch values (wood 9-17%; wire 10-16%) and is
probably related to the high pressure (80 psi) wash used to remove debris from the screens (NUSCo 1982,
1983, 1984, 1985, 1986).

A fish return system (sluiceway) was constructed at Unit I and began operating in December 1983.
Prior to the sluiceway operating at Unit 1, and presently at Unit 2, 100% mortality occurs to organisms
impinged at MNPS on non-impingement sampling days. On those days that impingement counts were
made, survival of lobsters impinged at Units 1 (1975-83) and 2 (1975-1985) ranged from 64-80% (NUSCo
1982, 1983, 1984, 1985, 1986). Generally, highest mortality of lobsters occurred during the peak molting
period when lobsters are soft and easily damaged and during the later summer months when water
temperatures are highest (NUSCo 1982, 1983, 1984, 1985, 1986). The design and operation of the Unit
3 traveling screens should improve survival and minimize damage to lobsters associated with the
impingement process at MNPS. A low pressure (10 psi) screen wash will be used to remove organisms
from the screens. The organisms are carried from a fish trough to a sluiceway which returns the organisms
back to Niantic Bay.

34

SUMMARY

1. Annual total CPUE from 1976 to 1985 ranged from 0.56 to 2.10 lobsters per trap. Total CPUE was
significantly higher for wire than wood pots. However, the CPUE of legal lobsters (>81 mm CL)
was similar for wood and wire pots. During 1985, low CPUE values at the Intake were attributed
to dredging activities in the vicinity of the intake structures.

2. Size frequency distributions indicated that wire pots caught significantly more small lobsters ( < 75
mm) than did wood pots. Since wire pots have been used, annual mean CL's have been consistent
(range 70.8-71.8). A strong prerecruit size class was observed during 1982 and resulted in record
landings throughout LIS in 1983 and 1984.

3. Male to female sex ratios of lobsters were close to 1:1. However, the Twotree station, 1.5 km offshore,
has yielded consistently higher numbers of females, when the three sampling stations were compared.

4. The size frequency distributions of berried females and abdomen width/carapace length ratios of
females indicated that female lobsters attain sexual maturity in this area at about 50 mm. Twotree
had consistently higher proportions of berried females of the three stations.

5. The frequency of molted lobsters in the catch varied over years. Although peaks occurred in early
summer, in some years fall molting peaks were also observed. Growth per molt averaged 14.1% for
males and 13.7% for females.

6. The percentage of culls ranged from 9.0 to 17.4%; more lobsters collected in wood pots experienced
claw loss (14.4%) than lobsters caught in wire pots (12.7%).

7. Since 1975, we tagged 47,259 lobsters and subsequently recaptured 8,053 (17%). Commercial lobster-
men recaptured 13,394 (28%) of the tagged lobsters released in our area.

8. Our tagging studies indicate lobster movements are mostly restricted to the local area since 91% of
the commercial recaptures were made within the study area. However, some lobsters moved more

35

than 100 km out of I, IS, and were caught on the edge of the continental shelf (Block and Hudson
canyons).

9. Ixjbster larvae entrainment studies conducted in 1984-85 provided better estimates of entrainment
losses than estimates made from ichthyoplankton samples. More lobster larvae were collected in night
samples than in day samples. Higher numbers of lobster larvae in night samples were related to larval
behavior and intake structure design.

10. Since 1975, an estimated 1 1,359 lobsters were caught on the intake traveling screens at MNPS. Since
it began operating at Unit 1, a fish return system improved the overall survival of impinged lobsters.

CONCLUSION

Results from our studies indicated that the local lobster population is highly exploited; more than
90% of legal lobsters are removed by fishing. The commercial and recreational catches were highly
dependent on the number of lobsters in the prerecruit size class. Because lobsters require at least 4 years
of growth before they are vulnerable to our traps, and an additional 2-3 years to reach marketable size,
there is a lag of about 6 years between the time of a potential impact on larvae and the time at which we
can detect that impact. Therefore, plant induced impacts or lack thereof on larval stages that may have
occurred since 1975 might have been observed in the adults caught in our traps beginning in 1981-82; yet,
thus far, the data do not indicate such a stress. Dredging activities in the vicinity of the intakes displaced
lobsters from that area; however, lobsters are expected to return soon after the sediments have stabilized.

The sensitivity of our program in defining population trends (i.e., observing the strong prerecruit class
in 1982) and impacts (displacement of lobsters as a result of dredging) is vital to our evaluation of impacts
associated with the operation of three units at Millstone Point. If changes occur in the local lobster
population, they will be detected by the alteration of the basic population parameters now being collected.
The stability of these parameters after the start up of Unit 3 will demonstrate the effects (if any) of MNPS
operations on the local lobster population.

36

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Dept. of Environ. Protection, Mar. Fish. 244p.

Campbell, A., and A.B. Stasko. 1985. Movements of tagged American lobsters, Homarus americanus,
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Collings, W.S., C.C. Sheehan, S.C. Hughes, and J.L. Buckley. 1981. The effects of power generation
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Cooper, R.A. 1970. Retention of marks and their effects on growth, behavior and migrations of the
American lobster, Homarus americanus. Trans. Amer. Fish. Soc. 99:409-417.

37

, R.A. Clifford, and CD. Newell. 1975. Seasonal abundance of the American lobster, Hnmarus

americ.anus, in the Boothbay Region of Maine. Trans. Amer. Fish. Soc. 104:669-674.

, and J.R. Uzmann. 1980. Ecology of Juvenile and Adult Homarus americanus. Pages 97-142 in

J.S. Cobb, and B.F. Phillips, eds. The Biology and Management of Lobsters, Vol II, Academic Press,
Inc. New York.

Ennis, G.P. 1971. Lobster {Homarus americanus) fishery and biology in Bonavista Bay, Newfoundland.
1966-70. Fish. Mar. Serv. Tech. Rep. 289, 46p.

. 1974. Observations on the lobster fishery in Newfoundland. Fish. Mar. Serv. Tech. Rep. 479,

21p.

. 1980. Size-maturity relations and related observations in Newfoundland populations of the

lobster {Homarus americanus). Can. J. Fish. Aquat. Sci. 37:945-956.

. 1984. Small-scale seasonal movements of the American lobster, Homarus americanus. Trans.

Am. Fish. Soc. 113:336-338.

Fogarty, M.J. editor. 1983. Distribution and Relative Abundance of American Ix)bster, Homarus
americanus Larvae: New England Investigations during 1974-79. NOAA Tech. Rep. NMFS SSRF-775,
64p.

, D.V.D. Borden, and H.J. Russell. 1980. Movements of tagged American lobster, Homarus

americanus, off Rhode Island. Fish. Bull. U.S. 78:771-780.

Ilerrick, F.II. 1911. Natural history of the American lobster. Bull. U.S. Bureau Fish. 29:149-408.

Hughes, J.T., and G.C. Matthiessen. 1962. Observations on the biology of the American lobster
Homarus americanus. Limnol. Oceanogr. 7:149-408.

38

Jolly, G.M. 1965. Explicit estimates from capture-recapture data with both death and immigration-
stochastic model. Biometrika 52:225-247.

Keser, M., D.F. Landers, Jr., and J.D. Morris. 1983. Population characteristics of the American lobster,
Homarus americanus, in eastern Long Island Sound, Coimecticut. NOAA Tech. Rep. NMFS SSRF-770,
7p.

Krouse, J.S. 1973. Maturity, sex ratio, and size composition of the natural population of American
lobster, Homarus americanus, along the Maine coast. Fish. Bull. 71:165-173.

. 1980. Summary of lobster, Homarus americanus, tagging studies in American waters (1898-1978).

Can. Tech. Rep. Fish. Aquat. Sci. 932:135-140.

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along the coast of Maine. U.S. Dep. Commer. NOAA Tech. Rep. NMFS SSRF-747:12p.

, and J.C. Thomas. 1975. Effects of trap selectivity and some population parameters on size

composition of the American lobster, Homarus americanus, catch along the Maine coast. Fish. Bull.
73:862-871.

Kurata, II. 1962. Studies on the age and growth of Crustacea. Bull. Hokkaido Reg. Fish. Res. Lab.
24:1-115.

lenders, D.F., Jr., and M.M. Blake. 1985. The effect of escape vent regulation on the American
lobster, Homarus americanus, catch in eastern Long Island Sound, Connecticut. Trans. 41st Annual
N.E. Fish and Wildlife Conference, 9p.

Lund, W.A., Jr., and L.L. Stewart. 1970. Abundance and distribution of larval lobsters, Homarus
americanus, off southern New England. Proc. Natl. Shellfisheries Assoc. 60:40-49.

, and C.J. Rathbun. 1973. Investigation on the lobster. NOAA Tech. Rept. NMFS Project No.

3-130-R, 189p.

39

MauchlLne, J. 1976. The Hiatt growth diagram for Crustacea. Mar. Biol. 35:79-84.

NUSCo (Northeast Utilities Service Company). 1978. Monitoring the Marine Environment of I,ong
Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Annual Report, 1977.

. 1982. Lobster Population Dynamics-A Review and Evaluation. Pages 1-.12 in Monitoring the

Marine Environment of Ixsng Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut.
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Long Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Annual Report 1982.

. 1984. Lxibster Population Dynamics. Pages 1-25 in Monitoring the Marine Environment of

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I^ng Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Annual Report 1984.
. 1986. Lobster Population Dynamics. Pages 1-29 /« Monitoring the Marine Environment of

I-ong Island Sound at MUlstone Nuclear Power Station, Waterford, Connecticut. Annual Report 1985.

Pecci, K..I., R.A. Cooper, CD. Newell, R.A. Clifford, and R.J. Smolowitz. 1978. Ghost fishing of
vented and unvented lobster, Homarus americanus, traps. Mar. Fish. Rev. 40:9-43.

Russell, II.J., C V.D. Borden, and M.J. Eogarty. 1978. Management studies of inshore lobster resources
completion report. No. L074-1-RI(1):1. R.I. Fish and Game, 75p.

Saila, SB., and J.M. Flowers. 1968. Movements and behavior of berried female lobsters displaced
from offshore areas to Narragansett Bay, Rhode Island. J. Cons. Int. Explor. Mer. 31:342-351.

Scarratt, D.J. 1964. Abundance and distribution of lobster larvae {Homarus americanus) in
Northumberland Straits. Fish. Res. Board Can. 21:661-680.

40

1970. I^aboratory and field tests of modified sphyrion tags on lobsters {Homarus americanux).

J. Fish. Res. Board Can. 27:257-264.

1973. Abundance, survival, and vertical and diurnal distribution of lobster larvae in

Northumberland Straits, 1962-63, and their relationships with commercial stocks. J. Fish. Res. Board
Can. 30:1819-1824.

, and P.F. Flson. 1965. Preliminary trials of a tag for salmon and lobsters. J. Fish. Res. Board

Can. 22:421-423.

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Stasko, A.B., and A. Campbell. 1980. An overview of lobster life history and fishery in southwestern
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42

Contents

EXPOSURE PANEL PROGRAM 1

INTRODUCTION 1

EXPOSURE PANEL STUDY 3

MATERIAI^ AND METHODS 3

DATA ANALYSIS 8

RESULTS 10

Fouling Species 10

Wood-boring species 16

DISCUSSION 23

DISTRIBUTION STUDY OF TEREDO NAVAUS AND TEREDO BARTSCHI 25

MATERIALS AND METHODS 25

DATA ANALYSIS 27

RESULTS 27

DISCUSSION 29

TIMBER STUDY 30

MATERIALS AND METHODS 30

DATA ANALYSIS 31

RESULTS 32

DISCUSSION 36

SUMMARY 39

CONCLUSIONS . 40

REFERENCES CITED 41

EXPOSURE PANEL PROGRAM

INTRODUCTION

The exposure panel program monitors the abundance of fouling and wood-boring organisms in the
vicinity of the Millstone Nuclear Power Station (MNPS). Since 1975, when the subtropical shipworm,
Teredo bartschi, was first collected in the MNPS effluent, the primary focus of this program has been the
monitoring of shipworms. Marine woodborers and specifically shipworms are primarily responsible for
the decomposition of wood in marine and estuarine waters. In the last 25 years, as industrial warm water
effluents increased in number, several investigators reported increased growth and fecundity of shipworms
within these thermally enhanced environments (Naylor 1965; Board 1973; Turner 1973; NUSCo 1982).
For example, T. bartschi and 7". furdfera caused extensive damage to marinas in the vicinity of the Oyster
Creek Nuclear Generating Station, New Jersey in 1971 (Turner 1973; Hoagland and Turner 1980; Hoagland
1981). Teredo bartschi primarily occurs south of Cape Fear, North Carolina and in the coastal waters of
the Gulf of Mexico. Although this species has not been collected beyond the influence of the undiluted
effluent at MNPS, we have conducted special studies between 1981 and 1985, and established that T.
bartschi can survive winter water temperatures in the Millstone Point area and reproduce at local summer
temperatures (report in preparation).

Fouling organisms, plants and animals that colonize new substrata, are also important in the exposure
panel program, for two reasons. First, some fouling species are sensitive to thermal stresses (Naylor 1965;
Cravens 1981) and the survival and growth of their sessile adult stages are influenced by the water quality
suiTounding the substratum to which they attach (Hillman 1975, 1977). Second, their abundance may
affect the recruitment of wood-boring species (Weiss 1948).

Artificial substrata have been used to study community structure and temporal variability of fouling
and wood-boring organisms (Turner 1947; Cairns 1982; Manyak 1982). Materials such as glass, plexiglass,
ceramic tiles, asbestos-cement and various types of wood have been used as zirtificial substrata. Although
the type of substratum, length of exposure period, and deployment strategies influence the patterns of
community colonization (Grave 1928; Zobell and Allen 1935; Schoener 1974; Shafto 1974; Osman 1977;

Sutherland and Karlson 1977), these factors can be standardized to allow comparisons between communities
that develop at different sites, or in different seasons. Several environmental monitoring programs have
used exposure panels to assess effects of thermal effluents (Cory 1967; Frame 1968; Cory and Nauman
1969; Nauman and Cory 1969; Hillman 1975, 1977; Young and Frame 1976; NAI 1979; Maciolek- Blake
et al. 1981; Osman et al. 1981; NUSCo 1982). Our Exposure Panel Program objectives are:

1. to monitor the abundance of marine woodborers at five sites in the Millstone Point area,

2. to quantify the loss of wood associated with the presence of woodborer populations in the vicinity
of MNPS,

3. to monitor the dispersal of Teredo bartschi in terms of distance from the Millstone Quarry, and,

4. to monitor the abundance of prevalent fouling organisms, and to investigate their relationship to
woodborer abundances in the Millstone Point area.

To achieve these objectives, three separate studies were conducted. The first (Exposure Panel Study)
used exposure panels to monitor the abundance of fouling and wood-boring species, as well as the
associated wood-loss. The second study (Distribution Study of Teredo navalis and Teredo bartschi) used
exposure panels deployed in close proximity to the MNPS discharge to monitor the distribution of
shipworms, in relation to the thermal effluent. The third study (Timber Study) used commonly available
dock building materials to quantify wood-loss.

The purpose of this report is to provide a summary of results from all Exposure Panel Program
studies performed during 2-unit operation. Space limitations required considerable condensation of infor-
mation; more detailed data are included in Appendix EP I.

EXPOSURE PANEL STUDY
MATERIALS AND METHODS

T'ouling and wood-boring organisms have been monitored in the vicinity of Millstone Point since
1968. This report summarizes data collected from 1979 to 1986, following evaluation and modification of
the methodology and objectives of the exposure panel program. These changes were based on the
recommendations from several studies that critically reviewed our program (Brown and Moore 1977;
Battelle 1978a, 1979; NUSCo 1983). The most important changes made were: (1) introduction of replicate
panels, (2) reduction of the exposure period from twelve months to six months, and (?>) restriction of data
collection to the wooden side of each panel. Adding replicates increased the power of our statistical
analyses, and reducing the exposure period decreased the likelihood that a panel would be entirely degraded,
and lost before collection. Since the major concern in fouling species was to determine their influence on
the abundance of woodborers, only data from the community that developed on wooden panels were
needed for our analyses.

The present study used sets of six replicated wood panels submerged at five sites, that were grouped
as: treatment sites, White Point (WP) and Fox Island (Fl), where potential power plant impacts during
3-unit operation may occur; control sites, Black Point (BP) and Giants Neck (CjN), located well beyond
the area of predicted power plant influence; and one impacted site, FfTIuent (FF), which was in the
Millstone Quarry where panels were exposed to maximum AT's. Water temperatures at FF from 1978-1986
averaged 9-10 "C warmer than those recorded at the Intakes of MNPS Units 1 and 2. The Intake
temperatures were considered to represent ambient conditions; seawater temperatures at WP and FI did
not vary more than 2 °C from ambient (NUSCo 1982). Water temperatures were derived from the
Environmental Data Acquisition Network (FDAN), and from continuous strip chart recorders.

Each of six exposure panels consisted of a knot-free pine board (25.4 x 9.5 x 1.9 cm) which had one
face covered by plexiglass. Only the uncovered wood side of each panel was processed. Sets of six
replicated panels were bolted to a stainless steel rack which was attached to a stainless steel frame at each
site (Fig. 2). The rack and frame assemblies deployed at WP, FI, BP, and GN were suspended from docks
by ropes in waters not exceeding 2 m in depth; the lower edge of the panels was maintained 0.2 ra off

Sites:

Exposure Panel Study

WP, n, EF. BP. GN

Distribution Study of Shipworms

100m, 500m, 1000m

Timber Study

WP, n. EF, NB, GN

Figure 1. Location of exposure panel and timber sampling sites in the vicinity of the Millstone Nuclear Power Station,
(WP = White Point, Fl = Fox Island, EF = Effluent, BP = Black Point, NB = Niantic Bay Yacht Club,
GN = Giants Neck, 100 m = trawl-line at 100 m, 500 m = trawl-line at 500 m, 1000 m = trawl-line at
1000 m).

the bottom. At EF, two rack and frame assemblies were used; the first 1 m below the water surface, and
the second about 1 m off the bottom at a depth of 10 m. This design was adopted to identify organisms
that have a settling preference for substrata near the surface, and those that settle near the bottom.

Figure 2. Frame and rack assembly used for holding six-month, six-replicale exposure panels at sites in the vicinity of
the Millstone Nuclear Power Station.

The panels were placed at each site in February, May, August and November and were collected six
months later in August, November, February and May, respectively. This provided four exposure periods,
each overlapping the next by three months. At the start of each exposure period, one rack of panels was
removed for processing and a new rack with fresh panels was deployed. Throughout this report the
exposure periods will be referred to using the following abbreviations: Aug-Feb, Nov-May, Feb-Aug and
May-Nov. Each abbreviation refers to the month of panel deployment followed by the month of panel
collection.

The temperature regimes in each of these exposure periods were different (Fig. 3). Aug-Feb began
when ambient water temperatures were warmest (> 20 "C) and ended when water temperatures were
coldest ( < 2 °C). Feb-Aug began when water temperatures were coldest ( < 2 °C) and ended when water
temperatures were warmest ( > 20 °C). Nov-May occurred during the coldest months (average = 5.8 "C)
of the year and May- Nov occurred during the warmest months (average = 17.2 °C). Seawater temperatures
in this report were based on data collected from 1978-1986 and the monthly averages were based on the
interval from the 15th of one month to the 15th of the next.

After collection, panels were either placed in flowing, filtered seawater and processed inmiediately or
frozen and processed at a later time. Primary cover, as a percentage, was estimated for each organism
that occupied more than 1% of the panel surface, e.g., barnacles, bryozoans, tunicates and some algae.
In addition, primary cover was estimated for other classifications such as freespace, mud and the dead tests
of fouling species, to complete the description of total primary cover for each panel. Numerical abundance
was determined for barnacles and mussels by counting the individuals on each panel. If the number of
individuals per panel exceeded 100, six subsamples of 1 x 1 inch were randomly selected, three from the
upper half and three from the lower half of the panel.

The abundance of woodborers was determined after the panel had been scraped of fouling species.
All individuals of the genera Limnoria and Chelura were counted when densities were less than 100
individuals per panel; otherwise, the subsampling scheme previously described for barnacles and mussels
was used. Subsampling was always conducted evenly between the top half and the bottom half so that
approximately 100 individuals were collected from each panel. After assessing the limnorid and chelurid
abundances, panels were frozen and subsequently radiographed using a 250 kV X-ray tube
(80 kV, 5 mA, for 1.2 min). The radiographs were used to visually estimate the number of shipworms.
Teredo navalis and T. bartschi, and the percentage of wood lost per panel. The percentage of wood lost
was expressed as the average "wood-loss" assigned to the the entire panel by rating the general proportions
of bright areas, caused by various densities of shipworm tubes and the dark areas caused by various degrees
of wood-loss. To determine the species of shipworms collected, shipworms were randomly removed from
the panels until all or at least 100 individuals were identified from each site. Shipworms < 5 mm in
length were classified only as juvenile teredinids because their pallets were too small and underdeveloped
for making accurate identifications.

Figure 3. The average monthly seawater temperatures from 1979-1986 during the four six-month exposure periods of
the Exposure Panel Program at the Millstone Nuclear Power Station (E = effluent, A = ambient). Note that these
monthly averages are from the 15th of one month to the 15th of the next.

In 1985 and 1986, a second estimate of wood-loss was obtained, based on weight. This measure
compared the pre-deployment weight of each panel with its weight after retrieval. Panels were dried at
80 °C for 96 h and weighed to the nearest 0. 1 g before deployment. After collection and panel processing,
each panel was soaked in 10% HCl for at least 48 h to dissolve calcium carbonate tubes secreted by
shipworms. Next, the panel was soaked for at least 48 h in two changes of fresh water to rinse the HCL
away before the panel was oven dried at 80 "C for 96 h. Panels were weighed to the nearest 0.1 g
immediately upon removal from the drying oven.

DATA ANALYSIS

The data represented in this report comprise five collection years prior to three-unit operation at
MNPS. The first set of panels was deployed in November 1978 and the last set of panels was collected
in May 1986. The collection years summarized in this report are: 1979 with three exposure periods, 1980
and 1981 with four exposure periods each, and more recently 1985 and 1986 with two exposure periods
each (Table 1). The monitoring of these panels was suspended from November 1981 to February 1985
(Appendix EP II, U.S. NRC, Docket Nos. 50-245 and 50-336, LS05-81-04-006, Exposure Panels) to
conduct special studies concerning the life histories of two shipworms. Teredo navalis and T. bartschi, in
relation to the mixing of effluent and ambient water at MNPS (report in preparation). These studies were
undertaken to acquire a better understanding of the limiting factors which restricted T. bartschi to the
Millstone Quarry.

The four exposure periods in each collection year do not represent a continuum because each period
overlaps the next by three months. Therefore, all averages and other summary statistics were computed
by exposure period. Data reported as percentages of primary cover were the estimated proportions of
exposed wood surface found covered by the most common species of foulers. Since all the exposure
panels were of equal size, the percentages of cover were treated as regular (or additive) count-data rather
than as ratios. These data for fouling species were based on 197 cm of panel surface, while wood-loss
estimates were based on the entire volume of a panel, or 422 cm .

Table 1.

The number of six-month exposure panels collected from 1979-1986 in the vicinity
of the Millstone Nuclear Power Station.

Collection

Exposure

Periods

Site

Year

Aug - Feb

Nov - May

Feb - Aug

May - Nov

1979

J

6

6

6

1980

6

6

6

6

W P

1981

6

6

6

6

1985

6

5^

1986

6

6

--

Total

18

24

24

23

1979

6

6

6

1980

6

6

6

6

F I

1981
1985

6

6

6

3

6

4

1986

6

6

--

Total

18

24

18

18

1979

-

6

6

6

1980

6

6

6

6

E F

1981

6

6

6

6

1985

-

-

6

6

1986

6

6

-

-

Total

18

24

24

24

1979

-

1980

-

-

-

-

B P

1981
1985

--

-

3

2

1986

3'

6

Total

3

6

0

0

1979

6

6

6

1980

6

6

6

6

G N

1981

6

6

6

6

1985

-

6

6

1986

6

6

-

Total

18

24

24

24

A dash ("), unless otherwise footnoted, indicates that no panels were deployed or collected.
Panels lost during Hurricane Gloria (Sept. 1985).
Panels exposed for three months.
Panels exposed for nine months.

RESULTS
Fouling Species

Primary Cover. The surfaces of the panels were covered with two types of marine fouling, that which
was alive and that which had died prior to collection. These two components comprise the total primary
cover. At WP, FI and GN total primary covers were largest during Feb-Aug, and at EF during Nov-May.
At WP, FI and GN covers were lowest in Aug-Feb, and at EF in Feb-Aug (Fig. 4). The average primary
cover on EF panels was 51%, while the combined average cover for the other sites was 29%.

Of the live organisms, 6 plants and 24 animals were considered dominant. The criterion for determining
this dominance was whether a species appeared among the five most abundant at any site during any
exposure period. After averaging primary covers from 1979-1986 by exposure period, the dominant foulers
accounted for 88-100% of the living cover on panels (Table 2). The most dominant organisms at ambient
water sites were Balanus crenatus, Codium fragile, Cryptosula pallasiana, Botryllus schlosseri, Laminaria
saccharina, and B. ehurneus. The most dominant organisms at EF were B. improvisus and Mytilus edulis.

As a taxonomic group, barnacles represented the most common genus on our exposure panels.
Balanus crenatus, B. improvisus, B. eburneus and Balanus juveniles accounted for large primary covers
throughout the study (Fig. 5). Balanus amphitrite, although collected at every site, was generally responsible
for less than 1% of the total primary cover and, for this reason, it was not included in Figure 5. In
Nov-May collections, these four barnacles contributed from 33% (EF) to 100% (FI) of the live cover at
all sites and in Aug-Feb they contributed 76% of the live cover at EF. Balanus crenatus was abundant
at all sites during Nov-May, the coldest exposure period. Balanus eburneus was most dominant at all sites
during the warmest exposure period, May-Nov. Balanus juveniles were most abundant on panels collected
in May and November, indicating that these two months are within the peak setting periods for barnacles
in the Millstone Bight.

Numerical Abundance. Six fouling species were monitored by counting the number of individuals
attached to our exposure panels: Balanus amphitrite, B. crenatus, B. improvisus, B. ehurneus, Balanus
juveniles and Mytilus edulis (Table 3). The temporal and spatial trends in numerical abundance were
generally similar to those discussed for primary cover data. Balanus amphitrite settled on panels in very

10

Aug— Feb

SITE

100
90
80
70-
60
50
40
30 i
20
101

Nov— May

i

SITE

Feb— Aug

May— Nov

i

SITE

DEAD SARNACLfS

SITE

n-^vv^M DEAD BARNACU

Figure 4. Mean primary covers of attached fouling organisms on wood panels during each of the four six-month
exposure periods from 1979-1986 in the vicinity of the Millstone Nuclear Power Station.

Table 2. Dominant taxa from 1979-1986 based on the average percent surface cover of the

six-month exposure panels collected in the vicinity of the Millstone Nuclear Power
Station. T = trace or less than 0.05% cover.

RANK

TAXA

WP

FI

I T

EF

BP

GN

TOTAL
% COVER

AUG -

FEB

1

Codium fragile

T

T

27.3

27.3

2

Balanus improvises

1.2'

0.1

21.6

0.1

0.2

23.2

3

Botryllus schlosseri

12.0'

1.1

M

4.8

20,3

4

Cryptosula pallaslana

24

6.0

0.1

lA

0.3

10.4

5

Balanus eburneus

T

T

■u

2.7

6

Botrylloides leachii

-LS

2.5

7

Bugula spp.

T

L6

0.3

-

0.5

2.4

8

Balanus juveniles ( < 2mm)

0.1

0.2

1.0

T

M

1.9

9

Mytilus edulis

0.1

T

lA

T

1.6

10

Tubularla crocea

T

LI

1.5

11

Balanus amphitrite

0.7

0.5

0.1

0.1

1.4

12

Molgula spp.

0.2

T

--

Li

1.3

13

Halecium spp.

1.2

T

1.2

14

Hydrozoa

0.7

-

0.7

15

Serpulid tubes

T

T

0.3

0:4

T

0.7

16

Barensia spp.

-

0.3

0.3

-

0,6

17

Alcyonidium spp.

-

--

0^

0,6

18

Ceramium rubrum

T

T

OA

T

0.4

19

Nicloea venustula

-

--

-

OJ

0.3

Total % cover

17.9

10.0

32.4

32.3

8.4

20.2-

NOV -

MAY

1

Balanus crenatus

10.8

35.2

10.7

6J

tl.2

74.6

2

Balanus juveniles ( < 2mm)

4.5

12.1

1.8

4.0

6^

28.6

3

Mytilus edulis

0.2

T

17.7

or

I

18,0

4

Laminaria saccharina

5.8

0,2

8.8

2J.

16,9

5

Alcyonidium spp.

--

9.2

-

9.2

6

Tubularia crocea

3.8

3.8

7

Balanus improvisus

T

\A

2^

-

3,8

8

Ohelia spp.

0.3

OJ

--

0,4

9

Punctaria plantaginea

-

I

--

T

10

Bacillariophyceae

T

T

-

I

T

Total % cover

21.6

47.6

45.0

21.6

19,5

31,1

Underlined percent covers indicate that the taxon was one of the top Tivc dominants for that site and exposure period.
Bold-face percent covers indicate that the taxon was the most dominant for that site and exposure period.
This is an average, i,e, sum of the total % covers divided by the number of sites.

12

Table 2. (cont'd)

RANK

TAXA

WP

FI

I T E
EF I

BP

GN

TOTAL
% COVER

I

Balanus crenatus

6.6

14.3

0.2

13.9

35.0

2

Balanus improvisus

1.2

0^

9.9

0.2

12.2

3

Cryptosula pallasiana

1.8

6.0

0.4

0.2

8.4

4

Balanus eburneus

2.8

0.3

3.5

0.6

7.2

5

Botryllus schlosseri

1.3

0.2

2.4

3.9

6

Ralfsia verrucosa

T

3.6

0.2

3.8

7

Balanus juveniles ( < 2mm)

0.7

0.3

1.6

0.5

3.1

8

Bugula spp.

1.6

0.3

T

0.2

2.1

9

Balanus amphitrite

0.9

0.3

0.1

0.6

1.9

10

Metridium senile

-

1.5

1.5

11

Halichondrla spp.

T

0.6

O.I

0.7

12

nbularia crocea

M

--

0.5

Total % cover

16.9

26.8

17.7

18.9

20.1

MAY -

NOV

1

Cryptosula pallasiana

7.7

23.7

3.4

34.8

2

Balanus eburneus

5.9

1.0

9.2

5.1

21.2

3

Balanus juveniles ( < 2mm)

2.2

1.3

10.3

3.2

17.0

4

Balanus improvisus

1.2

2.1

11.8

1.5

16.6

5

Halichondrla spp.

1.3

0.7

1.0

3.0

6

Bugula spp.

0.9

1.1

T

0.7

2.7

7

Balanus amphitrite

0.1

0.5

T

1.7

2.3

8

Schizoporella unicornis

1.4

0.3

1.7

9

Serpulid tubes

T

0.1

0.1

T

0.2

10

Crepidula plana

T

--

Oii

T

0,1

Total % cover

20.7

30.5

31.5

16.9

24.9

13

Aug-Feb

Nov— May

^

40-
30-

20-
10-

SITE

SITE

<

30-1

a.

70-

hi

>

C)

60 ■

o

V

50-

or

<

^

40-

rr

Q.

io-

7

s

zo-

3

Feb— Aug

SITE

100
90
30
70-
60-
50

May— Nov

SITE

Figure 5. Mean primary covers of four subtidal barnacles on wood panels during each of the four six-month exposure
periods from 1979-1986 in the vicinity of the Millstone Nuclear Power Station.

14

Table 3. The mean numerical abundance of six fouling species on six-month exposure
panels collected in the vicinity of the Millstone Nuclear Power Station, from
1979-1986.

M E A

N

c

; o u

N T ( ± 2 standard errors)

T A X A

SITE

Aug - Feb

Nov

May

Feb - Aug

May - Nov

w P

8.6

± 9.1

0.8

±

1.7

12.2 ± 10.0

0.3 ± 0.5

F I

0

± 0

0

±

0

1.9 ± 1.6

0.1 ± 0.1

Balanus amphitrite

E F

9.8

± 9.1

0

±

0

0.7 ± 0.7

0 ± 0

B P

1.3

± 1.3

0

±

0

...

G N

0.7

± 0.7

0

±

0

9.5 ± 8.9

0 ± 0

W P

0.1

± 0.1

113.5

~±

58.4

61.6 ± 29.3

0 ± 0

FI

2.0

± 2.8

350.9

±

187.2

8.7 ± 7.0

0.4 ± 0.5

Balanus crenatus

E F

5.2

± 4.6

27.4

±

13.6

0 ± 0

0 ± 0

B P

0

± 0

280.5

±

104.5

...

G N

0.1

± 0.1

247.8

±

188.6

83.6 ± 47.4

0.9 ± 1.3

W P

0.8

± 1.7

0

0

21.8 ± 19.2

8.2 ± 5.6

F I

O.I

± 0.1

0

±

0

0.3 ± 0.7

0.4 i 0.4

Balanus ehurneus

E F

7.4

± 6.1

0

±

0

7.5 ± 3.7

18.5 ± 9.3

B P

0

± 0

0

±

0

G N

0

± 0

0

±

0

3.0 ± 2.6

6.0 ± 4.4

W P

31.5

± 39.1

<0.1

± 0.1

18.5 ± 15.2

4.1 ± 2.9

F I

5.0

± 3.2

0.1

±

0.2

1.2 ± 1.3

0 ± 0

Balanus improvisus

E F

223.7

± 152.6

18.6

±

12.9

59.0 ± 25.1

64.5 ± 40.8

B P

2.3

± 1.8

0

±

0

..-

G N

1.2

± 1.0

0

±

0

4.5 ± 5.2

3.0 ± 2.4

W P

12.4

± 12.2

522.3

±

233.8

237.5 ± 177.8

10.8 ± 6.7

F I

62.2

± 36.0

826.9

±

448.4

8.2 ± 4.3

9.5 ± 6.7

Balanus juveniles

E F

53.6

± 44.1

9.2

±

2.6

49.5 ± 25.6

118.7 ± M.l

( < 2mm)

B P

0.7

± 1.3

820.3

±

287.2

G N

92.4

± 77.0

677.2

±

309.2

39.8 ± 19.4

18.8 ± 11.1

W P

149.3

± 1 10.1

27.9

±

19.5

7.1 ± 6.9

1.5 ± 2.8

F I

1.4

± 1.6

5.6

±

3.2

0.3 ± 0.3

0 -1- 0

Mylilus edulis

E F

167.9

± 134.6

128.4

±

74.1

0 ± 0

0 i- 0

B P

0

± 0

21.8

±

8.0

...

...

G N

3.9

;t 3.5

3.0

±

2.3

0.5 ± 0.3

0 i 0

15

low numbers. The maximum recruitment for this species was 12 individuals per panel during Feb- Aug.
Balanus crenatus settled in larger numbers than any of the other four barnacles and did so during the
coldest period of the year, Nov-May. Balanus eburneus consistently settled in low numbers on panels at
all sites during Feb- Aug and May- Nov. This species was also a dominant fouler at EF in Aug- Feb.
Balanus improvisus, like B. eburneus, was most commonly collected at EF and had 3 to 19 times more
larvae settling and surviving at EF than at any other site. Juvenile barnacles, which represent the pre-adults
of the above four barnacles, had strong recruitment onto panel surfaces throughout the study. The largest
numbers of juveniles settled during Nov-May, when B. crenatus was most abundant. Peak settlement of
Mytilus edulis occurred during Aug-Feb and Nov-May, and recruitment was largest at EF (Table 2). In
contrast, M. edulis was absent at EF in the Feb-Aug collections, while it was generally present in small
numbers at the ambient water sites.

Wood-boring species

Percentage of wood lost. Wood-loss of exposure panels was based on either direct inspection of each
panel (1979) or the visual assessment of panel radiographs (1980-1986). These types of estimates were
not as quantitative as that based on the actual weight loss of panels, but the precision of visual method
as compared to the weight method was very good (R = 0.98). Using a second-order polynomial
regression model (Fig. 6), the following equation was provided to predict the percentage of wood lost by
weight (WT) from that estimated by visual assessment of radiographs (V):

%WT loss = 6.668 + 0.4204 (%V loss) + 0.0032 (%V lossf

Wood-loss (V) was highest in May-Nov (average > 25%) and was primarily caused by Teredo navalis
(Fig. 7). Wood-loss during the Feb-Aug exposure period was < 5%, and ca. 10% during Aug-Feb.
Wood-loss from Nov-May was negligible, as T. navalis did not recruit during this period. The wood-loss
caused by T. bartschi at EF and juvenile teredinids at all sites did not exceed 1%. Among stations,
wood-loss has been greatest at GN and least at EF since 1979. At WP and FI, wood-loss has been similar
during all exposure periods except May-Nov, when wood-loss was nearly three times larger at WP than
at FI.

16

100-

•

80-

60-

^.^^9

40-

•

•

-^

20-
n

i^

• ^^^^'"^'^

PERCENT LOSS (RADIOGRAPH)

Figure 6. Comparison of wood-loss estimates from exposure panel weights versus visual assessments of radiographs
from 1985-1986. These data were collected as part of the Exposure Panel Program at the Millstone
Nuclear Power Station.

Numerical abundance. The Millstone area has two general groups of marine woodborers: crustaceans
and molluscs (Table 4). The crustaceans are represented in our data by two native taxa: IJmnoria spp.,
isopods, and Chelura terebrans, an amphipod. Because of the difficulties in identifying Limrtoria to the
level of species, these "gribbles" have been lumped together at the generic level. Recruitment of Limnoria
onto panels was greatest during the Feb-Aug (88-623 individuals/panel) and May-Nov
(up to 1670 individuals/panel) exposure periods (Fig. 8). Of the five sites monitored, GN and WP sup-
ported the greatest populations of these isopods. During the May-Nov exposure period, WP had 5 times
more Limnoria than any other site and nearly 9 times more C. terebrans. This latter species has a
commensal relationship with dense populations of limnorids, since the chelurids primarily feed on the thin

17

EFGW EFGW
F 1 N P F 1 N P

EFGW
F 1 N P

EFGW

F 1 N P

1 — Aug-Fob — 1 1 — Nov-Moy— 1

1— Feb-Aug— 1

1— May-Nov— 1

ivyvyvvi i navai is i
■■■■ T. QARTSCHI

1 T JUVENILES

Figure 7. Mean wood-loss caused by shipworms in six-monlh exposure panels collected from 1979-1986 in the vicinity
of the Millstone Nuclear Power Station.

paiiitions between limnorid tunnels (Barnard 1959). These large densities of wood-boring Crustacea at WP
during May-Nov were the cause of the increased wood-loss noted earlier at WP for this exposure period.

The moUuscan woodborers, shipworms, were represented in the Millstone area by Teredo navalis, the
native species and by T. hartschi, an immigrant species (Table 4). Shipworms were collected from every
site during three of four exposure periods (Fig. 9). Juvenile teredinids ( < 5 mm in length) representing
recent recruitment to panel communities, were most numerous during peak reproductive periods; August

18

The mean numerical abundance of five wood-boring taxa on six-month exposure
panels collected in the vicinity of the Millstone Nuclear Power Station, from
1979 -1986.

MEAN

C O U N T(i2 standard

errors)

T A X A

SITE

Aug

Feb

Nov

- May

Feb - Aug

May - Nov

w p

109.1

±

S2.3

40.7

± 20.5

581.2 ± 107.6

1670.5 ± 416.4

F I

38-0

±

27.7

0.5

± 0.5

179.3 + 102.0

164.9 ± 51.6

Limnoria spp.

E F

1.1

±

1.5

1.9

± 1.5

87.8 ± 54.9

6.8 i 5,9

B P

3.0

±

1.2

4.2

± 2.4

—

G N

201.8

±

90.6

307.8

± 147.1

623.2 ± 194.0

341,2 i 196.8

W P

0.8

±

0.8

0

± 0

18.3 ± 14.5

898.0 = 511.3

F 1

0.9

±

1.1

0

± 0

0 ± 0

0=0

Chctura terebrans

E F

0

=

0

T

i 0

0 I 0

0=0

B P

0

±

0

0

± 0

G N

3.1

±

4.4

0

± 0

0.9 ± 1.2

100,2 ± 138.3

W P

33.3

±

18.2

0

± 0

9.4 i 4.7

50,3 i 19.4

F 1

9 A

±

3.9

0

± 0

7.3 ± 5.0

15.1 ± 4.4

Teredo navalis

E F

8.1

±

4.1

<0.1

± <0.1

0.5 ± 0.3

7.4 ± 3.3

B P

6.0

±

4.2

0

± 0

...

G N

73.7

±

44.6

0

± 0

46.7 ±21.8

210.4 i 42.7

W P

0

-t

0

0

± 0

0 ± 0

0 ± 0

F I

0

±

0

0

± 0

0 ± 0

0 ± 0

Teredo hartschi

E F

13.4

±

10.8

0.1

± 0.1

1.0 ± 0,9

2.3 ± 1.5

B P

0

±

0

0

± 0

G N

0

±

0

0

± 0

0 ± 0

0 i 0

W P

0.1

±

0.1

0

± 0

23.8 ± 17 1

0 ± 0

Fl

0.1

±

0.1

0

± 0

12.6 ± 7,8

0.2 ± 0.4

Teredo juveniles

E F

0.4

±

0.4

0.6

i 0.2

1.0 ± 0.5

6.4 ± 6.4

B P

0

±

0

0

± 0

G N

0.1

±

0.1

0

i 0

71.6 ± 20,5

0.5 ± 0.7

at ambient water sites and November at EF. Teredinid larvae settling at EF in November were most
likely T. harlschi, since the major increase in recruitment from November to February was for this species.

Among sites, GN had the greatest recruitment of shipworms (210 shipworms/panel/year), and had
2-4 times as many shipworms per exposure period as any other site, while FI had the fewest
(15 shipworms/panel/year) among the ambient water sites. BP, established in 1985, has not been sampled
for a long enough period to determine temporal trends. EF was characterized by low abundances of all
wood-boring species throughout the study. However, this site supported the only population of T. bartschi,
which has been collected in the effluent since 1975.

Depth preferences of foulers and woodborers at EF. Two rack and frame assemblies of exposure panels
were monitored at EF to determine if fouling species or woodborers had any depth preferences for panels

19

JOOO-

B E F G W
P F I N P

I — Aug-Feb — I

E F G W
F I N P

-Nov-Moy — I

-Fob-Aug-

E F G W

B

E F G W

F 1 N P

P

F 1 N P

-May-Nov-

LIMNORIASPP.

CHELURA TEREBRANS

Figure 8. Mean numercial abundance of wood-boring Crustacea, Limnoria spp. and Chelura terebrans in six-month
exposure panels collected from 1979-1986 in the vicinity of the Millstone Nuclear Power Station.

placed 1 m below the surface or those placed 1 m above the bottom. Nine taxa were selected for
comparison based on their peak occurrences during the four exposure periods sampled from 1985-1986
(Table 5). Of these, four foulers and two woodborers had significantly larger abundances on one set of
panels as compared to the other in at least one exposure period. Alcyonidium spp., Balanus eburneus,
Tubularia crocea and Teredo navalis had their largest abundances on the panels close to the bottom, while
n. improvisus and Limnoria spp. were most abundant near the surface. Even though limnorids were most

20

B E F G W
P F I N P

I— Aug-Feb— I

B E F G W
P F I N P

I — Nov-Moy— I

E F G W
F I N P

-Feb-Aug — I

B E F G W
P F I N P

I— May-Nov— I

T. JUVENILES

Figure 9. Mean numercial abundance of the wood-boring mollusca, Teredo navalis. Teredo bartschi and Teredo
juveniles (< 5 mm in length), in six-month exposure panels collected from 1979-1986 in the vicinity of the
Millstone Nuclear Power Station.

abundant near the surface, T. navalis was much more destructive. Therefore, general wood-loss in panels
was greater near the bottom.

21

Table 5. A comparison between the recruitment of dominant fouling and wood-boring
species on six-month exposure panels suspended at two different depths in the
effluent of the Millstone Nuclear Power Station, from February 1985 - May 1986.

Taxa

Exposure
period

Mean

Abundance

Surface Bottom

Probability

Wilcoxon
t-test 2-sample Test

Alcyonidium spp.

Nov- May

11.8%^

17.8%

0.04*

0.07

Balanus eburneus

Feb-Aug

2.2^

8.7

0.007*

0.02*

May- Nov

2.5

9.8

0.008*

0.06

Balanus improvisus

Feb-Aug

9.8

14.8

0.21

0.23

Aug- Feb

15.0

0.3

0.003*

0.004*

Balanus crenatus

Aug- Feb

13.7

17.7

0.58

0.42

Nov- May

78.0

147.8

0.15

0.47

Mytilus edulis

Nov-May

70.2

91.0

0.26

0.38

Tuhularia crocea

Feb-Aug

0.0%

3.0%

0.01*

0.009*

Wood loss

May- Nov

4.5%

11.7% ■

0.008*

0.02*

Aug- Feb

3.0%

0.7%

0.13

0.10

Limnoria spp.

Feb-Aug

307.2

0.5

0.0001*

0.004*

May- Nov

21.2

1.3

0.07

0.04*

Teredo navalis

May- Nov

0.5

6.5

0.004*

0.004*

Aug- Feb

0.3

1.5

0.08

0.06

Teredo bartschi

Feb-Aug

4.2

3.3

0.50

0.61

May-Nov

3.8

7.7

0.19

0.23

Aug- Feb

2.0

1.7

0.81

0.80

Exposure periods listed are those which had peak recruitment for each species.

#% = average primary cover (n = 6)

# = average numerical abundance (n = 6)

Difference is significant at least at the 0.05 level.

22

DISCUSSION

Temporal changes in exposure panel communities are closely associated with seasonal water temper-
atures and the suites of fouling and wood-boring life stages which are available for settling. In Nov-May,
the coldest exposure period, panel communities were dominated by cold and temperate water species:
Balanus crenatus, Mytilus edulis and Laminaria saccharina. In May-Nov, the warmest exposure period,
these dominant species shifted to the warmer water assemblages of Cryptosula pallasiana, B. eburneus, B.
improvisus, Limnoria spp., Cfielura terebrans and Teredo navalis. These seasonal trends in recruitment for
fouling and wood-boring species have been well documented in other studies (Nair and Saraswathy 1971;
Osman 1977, 1978; Sutherland and Karlson 1977; Ibrahim 1981).

The fouling community at EF was different from those at ambient water sites; large primary covers
on EF panels were related to accelerated growth in response to elevated temperatures. Cory and Nauman
(1969) found that dry weight production of fouling species was on the average 2.8 times greater in the
power plant effluent at Chalk Point, Maryland than in its intake waters. Young and Frame (1976) reported
that the optimum temperature for growth of Balanus spp. was approached more closely during the winter
in the Oyster Creek power plant's discharge canal than in the intake canal where growth rate was reduced
by cold water.

Conversely, effluent temperatures during the wjirmest months of the year had negative effects. Set-
tlement and survival of some species were adversely affected by effluent temperatures, since seasonal
temperatures exceeded the upper tolerance levels for some of their life stages. Similar exclusion of temperate-
boreal species from the Millstone Quarry has been discussed in the Rocky Intertidal section of this report.
Laminaria saccharina, a temperate-boreal brown alga, has never been collected on panels at EF, yet was
a consistent dominant at ambient water sites in Nov-May. Adult stages of Mytilus edulis have an upper
thermal tolerance of 26-27 °C (Gonzalez and Yevich 1976; Johnson et al. 1983) and the effluent temperatures
exceeded 26°C from June to September. I^arge populations of mussels were observed in the Millstone
Quarry during several May collection periods, but totally disappeared during June and July. In addtion,
remains of dead barnacles and bryozoans were generally 2.5 times greater at EF than at other sites. This
abiotic cover peaked on EF panels during the warmest exposure period of the year (May-Nov).

2.1

To date, Teredo bartschi has been found only in panels exposed to undiluted effluent, but the
destructive potential of this species warranted a series of special studies, conducted from 1981 to 1985
(report in preparation). Teredo bartschi is a warm water immigrant, and differs from 7'. navalis in being
a long-term brooder instead of a short-term brooder. By brooding its veliger larvae to the pcdiveliger
stage before releasing them, 7'. bartschi pediveligers are able to reinfest wood near their parent populations,
which makes this species very destructive to a localized area after it has established a population (Hoagland
and Turner 1980; Turner 1973). In contrast, T. navalis veligers are released at the straight hinge stage and
require at least three weeks of development in the plankton before they metamorphose (Imai et al. 1950;
Culliney 1975). Teredo bartschi recruitment into EF panels occurred after August with the largest popu-
lations occuiring in the panels collected in February. However, our investigation concerning the life history
of this species has established that T. bartschi release pediveliger larvae throughout the year at EF tem-
peratures (report in preparation). This would suggest that the successful recmitment of this species requires
temperatures above 22 "C.

Wood-loss data prior to 1979 indicated that the EF site consistently experienced the heaviest annual
shipworm infestation of any of the ambient water sites (Battelle 1978b). This contradicted the 1979-1986
data as presented in this report. The reason for this discrepancy is that the location of the exposure panel
rack at EF was changed in 1979 from just off the bottom in shallow water to 1 m below the surface in
about 10 m of water. The depth preference data described in this report indicates that T. navalis occurred
in greater abundance 1 m off the bottom than at 1 m from the surface. Others have reported that this
species has a strong preference for setting close to the bottom (Grave 1928; Schellema and Tinjitt 1956;
Turner 1966; Nair and Saraswathy 1971). In fact, its preference is so pronounced that the location of our
panels 1 m of the bottom probably missed their peak zone of recruitment. Therefore the 1979-1986 data
may underestimate the abundances of woodborers on the bottom. We will evaluate the depth response
of T. navalis by placing a set of panels in pre- 1979 position, i.e., just off the bottom in shallow water.

In summary, the ambient water sites had similar fouling assemblages and trends in abundance from
1979-1986. Total primary cover at all sites was dominated by three barnacle species. Balanus crenatus was
most dominant at ambient water sites during Aug- Feb and Nov- May, and B. eburneus and B. improvisus
were most dominant during Feb-Aug and May-Nov. Other fouling species that consistently colonized over
5% of the panel surfaces at ambient sites were Cryplosula pallasiana, Botryllus schlosseri and Laminaria
saccharina. The primary covers of EF panels were different from those at ambient water sites; Balanus

24

improvisus, Tubularia crocea and Mytilus edulis, and Alcyonidium spp. had consistently large primary covers,
while Laminaria saccharina and Botryllus schlosseri were totally absent from EF assemblages.

Woodborer abundances vary from site to site and were dependent on the time of year the exposure
panels were exposed. Trends in primary cover did not appear to affect woodborer abundances. At ambient
water sites, Teredo navalis was the only shipworm collected. Woodboring Crustacea, Limnoria spp. and
Chelura terebrans, were most abundant at WP and GN. The EF site had the only population of T. bartschi
and this species appeared to recruit to panels only when effluent temperature exceeded 22 °C. Teredo
navalis colonized panels at EF later in the year than at ambient water sites.

Patterns of abundance and distribution of woodborers and other fouling organisms at the ambient
water sites were consistent and predictable from year to year, as were differences between the ambient
water communities and those that developed in undiluted effluent. Characteristics of the EF community
included enhanced primary cover, temporal shifts in peak abundance of individual species and total primary
cover, absence of cold water species, and the unique occurrence of a warm water shipworm, Teredo
bartschi. Further investigations of the factors that control the distribution of T. bartschi are detailed in
the next section.

DISTRIBUTION STUDY OF TEREDO NA VALIS AND TEREDO

BARTSCHI

MATERIALS AND METHODS

This study used panels located at 100, 500, and 1000 m from the cuts in the Millstone Quarry through
which the MNPS effluent flows into Long Island Sound (Fig. 1). In May of each year a total of 15
knot-free pine exposure panels without plexiglass backers were placed in three wire lobster pots attached
to each of three trawl-lines (Fig. 10). In November, nine panels from each trawl-line were collected,
leaving six panels to provide substratum for a stock population. Three panels were taken from each
lobster pot in a trawl-line and three new ones were added. In May of the following year all 15 panels
were collected and replaced with new ones. To date, only two exposure periods have been completed.

25

B. EXPOSURE PANEL

/

JL

3

(3

(3

r

£

Figure 10. Diagram of an exposure panel trawl-line used to sample the distribution of shipworms in relation to the
efriuent discharge point at the Millstone Nuclear Power Station (a. trawl-line of five lobster pots with the
locations of tfie 15 pine panels; b. pine panel showing the sections used for subsampling).

The panels collected in November were exposed during the period of peak recruitment for shipworms.
Therefore, only six of the nine panels collected from each trawl-line were selected for shipworm identification.
Each panel was cut into six equal parts, and all shipworms in one of the parts were removed and identified.
Because the parts chosen came from different locations in each panel (Fig. 10), the six parts processed

26

were, in fact, a "composite" of an entire panel. The same sampling scheme was used for each of the three
trawl-lines.

Shipworm infestation was assumed to be minimal in panels exposed from November to May. Hence,
all 15 panels were radiographed using the X-ray method described earlier, and if shipworms were present,
they were removed and identified.

DATA ANALYSIS

Data analyses consisted of comparisons between sites using observations made on panel sections
paired by their location in the panel. This type of pairing was necessary, because shipworm recruitment
rates vary with the location of the panel section observed (e.g., shipworm infestation is greatest on the
bottom and top ends of a panel). Parametric t-tests and non-parametric Wilcoxon 2-sample tests were
used to compare the occurrences of Teredo navalis between pairs of sites.

RESULTS

A total of 18 panels were collected in November 1985, after a six month exposure at distances of 100,
500 and 1000 m from the Millstone Quarry. Over 1500 shipworms were removed and identified from
these panels (Table 6). The estimated total recruitment of shipworms was 615 per panel at 100 m, 526 at
500 m and 388 at 1000 m. Teredo bartschi were collected only in panels at 100 m, and they represented
2.3% of the total number of shipworms which were collected at that distance. However, one of the 14
individuals collected was brooding pediveligers, indicating that T. bartschi can reproduce outside the quarry.

Both parametric and non-parametric statistical comparisons were made concerning the abundances of
shipworms by panel section and distance. None of the three comparisons among the sites were significant
at a = 0.05. However, there is a trend of decreasing abundance with increasing distance from the quarry
(Table 7). Lx)W number of observations and high degree of intra-site (within site) variability contribute
to the lack of statistical significance; more data may substantiate a distinct trend.

27

In May 1986, all 45 panels, representing all distances, were collected, x-rayed, and shown to be devoid
of shipworms.

Table 6. Distribution of shipworms in relation to the eflluent discharge point at

the Millstone Nuclear Power Station, from May - November 1985.

Distance

Species

Number per section Total no.

12 3 4 5 6 per panel Percent

100 m

Teredo navalis

145

116

49

32

161

98

601

97.7

100 m

Teredo bartschi

4

0

4

0

0

6

14^

2.3

TOTAL

615

500 m

Teredo navalis

85

83

58

98

92

110

526

100.0

500 m

Teredo bartschi

0

0

0

0

0

0

0

0.0

TOTAL

526

1000 m

Teredo navalis

98

83

73

43

54

37

388

100.0

1000 m

Teredo bartschi

0

0

0

0

0

0

0

0.0

TOTAL

388

One individual was brooding pediveligers.

Table 7. Statistical comparisons in the mean number of Teredo navalis collected in

exposure panels, in relation to the effluent discharge point at Millstone Nuclear
Power Station, from May - November 1985.

Pr

o b a

b

i 1 i t y

Mean

WUcoxon

Difference

n

difference

S E

t-test

2

-sample test

100 vs

500m

6

12.2

21.1

0.59

0.52

100 vs

1000m

6

35.2

19.8

0.14

0.26

500 vs

1000m

6

23.0

15.3

0.19

0.09

28

DISCUSSION

The panels at 100, 500, and 1000 m represent a series of samples collected along a straight line at
increasing distances from the quarry. The direction of this transect was the same as the ebb tide flow of
the effluent plume. The data described a consistent decrease in panel recruitment of Teredo navalis from
601 at 100 m to 388 at 1000 m. This trend may indicate that recruitment of 7'. navalis is enhanced m
the effluent mixing zone, even though the differences in shipworm densities were not statistically different
(p < 0.05) from 100 to 1000 m.

This was the first study investigating the distribution of Teredo bartschi beyond the undiluted effluent
or F-F site. Panels at the 100 m sampling site were within the effluent mixing zone, and were periodically
flushed by effluent waters; the depth at this site was 5 m. Incursion of effluent water permitted the
successful recruitment of T. bartschi in panels at 100 m. Studies on the life history of this species from
1983-1985 established that T. bartschi could grow and reproduce at ambient water temperatures in the
Millstone area (report in preparation), but may require higher effluent temperatures for successful recruit-
ment. The panels at 500 and 1000 m sampling sites were at depths of approximately 10 m and were not
exposed to effluent water, under 2-unit operating conditions. No T. bartschi were found at 500 or 1000 m.

A similar link between high temperatures and the distribution of this species has been indicated by
others; Teredo bartschi has been recorded outside its normal range only in the vicinities of thermal effluents.
Hoagland and Turner (1980) reported that T. bartschi was present in panels at the mouth of the Waretown
Creek and in Forked River from 1975 to 1978; both areas were in the mixing zone of the thermal plume
from the Oyster Creek Nuclear Generating Station, Bamegat Bay, New Jersey.

In summary, a reproductive population of Teredo bartschi was collected at a site 100 m outside of
the quarry cuts, within the mixing zone of 2-unit effluent. Preliminary data indicate that water temperatures
above ambient are needed for larval recruitment, i.e., some incursion of effluent water; however, additional
studies are needed to determine the exact conditions needed for T. bartschi settlement, and to determine
whether the local distribution of T. bartschi will expand under 3-unit operating conditions. Additional
studies may also substantiate the observed trend of increasing T. navalis abundance with decreasing distance
from the quarry cuts.

29

TIMBER STUDY
MATERIALS AND METHODS

This study used five different types of wooden blocks or "timbers" which were exposed to the marine
envirormient at five sites for periods of one to five years. The timbers (6.4 x 10,8 x 30.5 cm) were cut
from planks (6.4 x 24 x 300 cm) commonly used for building docks. The five types of wood were:
untreated Red Oak and Douglas Fir, and three types of chemically treated Southern Yellow Pine. The
three chemical treatments were; 20 lbs per ft creosote, 0.6 lbs per ft chromated copper arsenate (CCA),
and 2.5 lbs per ft CCA. The timbers were deployed at four sites used for monitoring fouling and
wood-boring species: White Point (WP), Fox Island (FI), Effluent (EF) and Giants Neck (GN), and at
a fifth site (Fig. 1), located at the Niantic Bay Yacht Club, Black Point (NB). The timbers were fastened
with plastic cable ties to wire lobster pots (Fig. 11). Three pots per site were deployed on the bottom
with timbers arranged so that all untreated wood blocks were attached to the same pot.

Three timbers of each type were collected at each site in November and new ones deployed. Four
replicate timbers of each type were placed at each site when this study began in March 1983, to be collected
in November 1985, 1986, 1987, and 1988. These timbers, deployed for long-term exposures, were not
replaced upon collection.

Wood-loss was quantified by comparing the weights of replicate timbers that have not been placed
in seawater (blanks) with those that have been exposed. Every year, three blanks of each type of timber
were cut from the same planks used to make timbers for deployment. After collection, the exposed timbers
were processed according to the following procedure. First the percentage of surface area covered by each
fouling species was recorded, and then the timbers were scraped clean and frozen. Next, they were
radiographed using a 250 kV X-ray tube and the approximate percentage of wood lost was visually
estimated from the radiographs. Wood-loss was expressed as the average of that percentage assigned to
the top left, top right, bottom left and bottom right quadrants of each timber and was accomplished by
rating the general proportions of bright areas, caused by various densities of shipworm tubes and the dark
areas caused by various degrees of wood-loss. Finally, the timbers and the blanks were sectioned into one
inch lengths and dried in a solar oven until they reached a constant weight. The untreated timbers were

30

Stction JisctrJed

Figure 1 1 . Diagram of a lobster pot (A), the location of timbers along its sides (B), and the dimensions of a timber
with the location of sections which are weighed (C). These limbers are used to monitor wood-loss caused
by marine woodborers in common building materials in the vicinity of the Millstone Nuclear Power Station.

acid-soaked and rinsed as described earlier for the exposure panels, but the chemically pre-treated timbers
were not acid-soaked because of the resulting hazardous reaction products.

DATA ANALYSIS

The data summarize three sampling years, 1983-1985, prior to three-unit operation at MNPS. The
first set of timbers was deployed in March 1983, and the last set was collected in November 1985.

31

The weight loss of exposed timbers was obtained by subtracting the weight of the exposed timbers
from the average weight of 15 sections obtained from the three replicate "blank" timbers. In addition,
since the dimensions of the timbers and the thicknesses of the sections varied from year to year, all weights
were converted to a standard density unit, grams per cubic centimeter (g/cm ).

In this report, the wood-losses for Douglas Fir and Red Oak were based on direct weighings. Direct
weights of chemically treated timbers would have been biased by the calcium carbonate tubes of shipworms,
as these timbers were not acid-soaked. Therefore, wood-losses for chemically treated woods were based
on radiographic estimates.

RESULTS

There was considerable variability in the dimensions and quality of the planks used in this study. Of
all the planks used, the Douglas Fir plank in 1983 and the creosote plank in 1984 were most dissimilar
in their general dimensions. The quality of the pressure treated woods used in 1984 was poor. The
creosote treated plank did not have 20 lbs of creosote per cubic foot because the density of these timbers
(g/cm^) was 39% lower than those in 1985. Similarly, the CCA treated sections in 1984 were dissimilar
to those in 1985. Weight data are not available for unexposed pressure treated timbers in 1983. To
account for all this variability, weight loss extimates were converted into grams per cubic centimeter (g/cm )
of wood (Table 8).

The correlation between the wood-loss estimates by weight to that by visual inspection of radiographs
was highly significant (p > 0.001). The second order polynomial equation used in the regression analysis
has an R^ of 0.81 (Fig. 12). The shape of this regression line relative to the data indicates that we
consistently overestimated wood-loss using the radiographic method.

Wood-loss for Douglas Fir and Red Oak are presented in Figure 13. Douglas Fir lost an average of
3 times more wood during a one year exposure than did the Red Oak, ranging from 30-70% loss vs.
5-55% loss. In general, timbers that lost 70% of their weight were so fragile that several severely degraded
timbers were lost from lobster pots.

32

Average weight of a section for each type 'of "blank " timber used in the Timber
Study at the Millstone Nuclear Power Station, from 1983-1985.

Average

dimensions

Avg. section

Avg, density

Length

Width

Height

Type of wood

Year

weight (g)

S E

C V

(g/cm')

(cm)

(cm)

(cm)

Douelas Fir

1983

108.4

2.3

8.3%

0.43

11.9

8.1

2.6

1984

86.8

0.9

4.0'!'n

0.46

11.4

6.3

2.6

1985

77.5

0.8

4.2»4

0.43

11.1

6.2

2.6

Red Oak

19S3

129.7

2.1

6. Pi

0.62

11.7

6.9

2.6

19S4

112.2

n.9

3.2'"o

0.63

11.0

6.2

2.6

1985

126.4

1.6

5.0"'o

0.75

10.8

6.0

2.6

Southern Yellow Pine

n.6 lbs/ft' CCA

1984

112.8

0.9

3.1%

0.50

12.1

7.2

2.6

1985

115.7

1.8

6.0%

0.64

11.1

6.3

2.6

2.5 lbs. ft' CCA

1984

111.7

1.0

3.6%

0.46

12.5

7.5

2.6

1985

119.0

1.6

5.1%

0.67

11.0

6.2

2.6

20 lbs, ft' Creosote

1984

165.1

3.4

8.1%

0.58

12.1

9.4

2.5

1985

169.5

3.1

7.1%

0.95

10.9

6.3

2.6

100-

"e

o

.•

■

E

•

Oi

80-

• • *

EC

•

/I

>-

y'^ •

UJ

•

z

60-

%/^ • *

o

•

'^ •

o

^^

• •

•

^y^*

01

^^

in

• ^

■^

O

40-

• •

•

_i

Q

•

•• •

^^,

O

^,^

•

O

5

•
•

X

•

•

1 —

20-

^

•

z

•

«•

tjj

-'^»

•

o

• •_•— ^* — '"*'

•

n.

0^

. •• •••/•.

PERCENT WOOD LOSS for ONE YEAR (Radiograph)

Figure 12. Comparison of wood-loss estimates from timber section weights versus visual assessments of radiographs
for all types of wood examined from 1983-1985. These data were collected as part of the Exposure Panel
Program at the Millstone Nuclear Power Station.

33

100

DF RO DF RO

NB WP

Figure 13. Mean annual wood-loss caused by marine woodborers from 1983-1985 in Douglas Fir and Red Oak
timbers in the vicinity of the Millstone Nuclear Power Station. Estimates are based on the weight of five,
one inch sections from each timber.

Radiographic estimates were used to describe wood-loss from chemically treated timbers. These data
indicated that wood-loss was greatly reduced in treated woods relative to untreated types (Fig. 14). Only
the cut surfaces of these timbers, which exposed areas with no chemical treatment, were su.sceptible to
recruitment of woodborers. However, shipworms were able to penetrate some areas of CCA treated wood
after they had settled and metamorphosed in untreated grains exposed by the cut surfaces.

Data concerning wood-loss from timbers exposed for more than one year indicated that wood-loss
can more than double during the second year of exposure (Table 9). Generally, Douglas Fir timbers were
totally degraded by woodborers after two years, while three years were required for Red Oak timbers to
reach 70% wood-loss. At EF, wood-loss of untreated timbers was considerably greater, and neither

34

Douglas Fir or Red Oak timbers lasted through two years of exposure. At EF and GN, CCA treated
timbers with untreated grain had up to 50% wood-loss after three years of exposure.

25

^ 20-

15

ID-

S'

C2 = 2.5 lbs/ft^ CCA)
C6 = 0.6 lbs/ft^ CCA)
OR = 20 Iba/ft^ Creosote)

EF = Effluent Site
Fi = Fox Island Site
GN = Giants Neck Site
NB = Niantic Bay Site
WP = White Point Site

CR C2 C6
K EFH

CR C2 C6
h- Fi — 1

CR C2 C6
f- GN H

CR C2 C6
H NB H

CR C2 C6
h- WP H

Figure 14. Mean annual wood-loss caused by marine woodborers from 1983-1985 in chemically treated Southern
Yellow Pine timbers in the vicinity of the Millstone Nuclear Power Station. Estimates are based on visual
assessments of radiographs.

35

Table 9. Percentage of wood-loss Trom timbers submerged for periods of I, 2, and
3 years in the vicinity of the Millstone Nuclear Power Station, from
1983-1985.

no. of

Percentage of wood lost

years

Type of wood

exposed

E F

F 1

G N

W P

Douglas Fir

I
2

68%

27%
82%

66%

48%

1

55%

4%

21%

8%

Red Oak

2

♦

49^0

68%

56%

3

•

70%

*

72%

Southern Yellow Pine

0.6 lbs/ft^ CCA

1

8%

1%

10%

2",'-.

2

12%

2%

2%

3

44%

15%

2.5 lbs/ft^ CCA

1

19%

1%

11%

10%

2

28%

6%

19%

21%

3

47%

26%

50%

...

20 lbs/ft^ Creosote

1

0%

0%

0%

2

0%

0%

0%

3

NOTE: The Douglas Fir and Red Oak data are based on direct weights and the
pressure-treated wood data are based on visual estimates of radiographs.
Timbers were lost from pots and assumed totally destroyed by woodborers.
— Timbers were lost from pots, but this loss was not related to woodborers.

DISCUSSION

The timber study quantified the annual loss of wood at the five sites in the vicinity of MNPS, and
detenmined the longevity of five types of wood commonly used in marine construction. The untreated
woods have provided direct weight data to compare wood-loss between sites, and the percentage of wood
lost in the chemically treated woods has been calculated on the basis of visual estimates of wood-loss
using radiographs.

The chemical treatments applied to the timbers protected the wood from woodborer attacks. However,
woodborers readily recruited into the untreated wood grain exposed by the preparation of timbers. Within
the first year, between 1-10% of the wood in the CCA treated timbers was lost and after three years

36

15-50% of the wood was lost. In addition, the adult shipworms appeared to be able to survive boring
through the lower concentrations of CCA, which existed beneath the treated surfaces of the timbers.
Woodborers were never observed penetrating the treated outside surfaces of a timber. The total protection
of creosote timber from wood-loss in 1983 and 1985, resulted from the effective penetration of this chemical
(20 lbs/cm ) throughout the interior wood grain of each timber. Other studies have concluded that the
CCA and creosote treated woods are very effective at deterring marine woodborers (Baechler et al. 1970;
Johnson 1977; Richards 1977, 1979; Johnson and Gutzmer 1981). Creosote (20 lbs/ft^) and CCA
(1.0 lbs/ft ) have been reported to withstand woodborer attacks for eight years, while test panels and piles
with very high retentions of CCA (2.5 lbs/ft ) have been reported to repel woodborers for 25 years (letter
from W.T. Henry to J.D. Land, Koppers-Hickson Canada, Ltd., 1976). In their studies small test blocks
were used and treated after being cut. In the present study, we used products and treatments available to
local builders.

Aruiually, there was a threefold greater loss of wood from Douglas Fir timbers than from Red Oak
timbers. Although Douglas Fir is seldom used in marine construction, oak planking and pilings are often
used locally. The reduced wood-loss as observed for Red Oak is the reason hardwoods have been used
in dock building. Oak pilings are much larger than our timbers and are set with the bark still on the tree,
which provides additional protection from wood-borers. However, untreated woods in the local marine
environments are readily attacked by borers.

Wood-loss varied from site to site, and FI had the least wood-loss of any of the sites sampled.
However, Red Oak timbers at EF lost over twice as much wood when compared to the Red Oak timbers
at ambient water sites. This was in contrast to data collected at EF using exposure panels, where wood-loss
of panels at EF never exceeded that observed at ambient water sites. The reason for this discrepency was
related to the location of the panels versus that of the timbers. Timbers were deployed directly on the
bottom, while the EF panels were suspended off the bottom. Even the lower frame and rack assembly
of panels deployed at EF was approximately one meter higher in the water column thcin were the timbers.
The fu-st inch of the timbers was usually embedded in the bottom sediments, which was the reason the
first section of the timbers was routinely discarded during processing. Therefore, the greater annual
wood-loss in timbers was caused by shipworms setting most heavily at the mudline, an occurrence
documented by others (Grave 1928; Scheltema and Truitt 1956; Turner 1966; Nair and Saraswathy 1971).

37

In conclusion, our objectives for the timber study are being met. The untreated timbers have provided
the needed database for quantifying wood-loss from site to site and year to year. The longevity of untreated
Douglas Fir and Red Oak have been determined, and that for the treated woods continues to be investigated.
Chemical treatments deter woodborer attack, but cutting treated timbers exposed unprotected surfaces. Of
our test treatments, only creosote was penetrating enough to provide protection to interior wood grain.
These data will be used to defme potential power plant impacts on wood-loss in the vicinity of Millstone
during three unit operation.

38

SUMMARY

1. The most abundant fouling species at ambient water sites (WP, FI, BP, GN) were Balanus crenatus,
Codium fragile, Cryptosula pallasiana, Botryllus schlosseri, Laminaria saccharina and Balanus eburneus
while the most abundant fouling species at EF (effluent site) were Balanus improvisus and Mytilus
edulis. Balanus eburneus, a wann water barnacle, was consistently more abundant at EF than at the
ambient water sites, and L. saccharina was never collected at the EF site. The identity and abundance
of these fouling species did not affect abundance of woodborers.

2. Characteristics of the EF community which were related to temperature included enhanced primary
cover, temporal shifts in peak abundance of individual species and total primary cover, absence of
cold water species, and the unique occurrence of a warm water shipworm, Teredo bartschi.

3. Teredo bartschi recruited into EF panels after August with their largest populations occurring in panels
collected in February. There is evidence to suggest that this species has a minimum setting temperature
of approximately 22 "C.

4. Teredo navalis was most abundant at GN in May-Nov, while Limnoria spp. and Chelura terebrans
were most abundant at WP in May-Nov. The low abundance of T. navalis at EF from 1979-1986
was caused by panel location. A second rack and frame assembly of panels will be relocated 0.2 m
from the bottom in shallow water to further evaluate the vertical distribution of woodborers at EF.

5. The occurrence of T. bartschi at 100, 500 and 1000 m from the MNPS effluent discharge point was
monitored. A reproductive population of T. bartschi was collected from panels at 100 m, after six
months exposure.

6. Our data describe a consistent decrease in panel recruitment of T. navalis from 601 at 100 m to 388
at 1000 m. This trend may indicate that recruitment of T. navalis is enhanced in the effluent mixing
zone.

39

7. Annually there was a threefold greater wood-loss from untreated Douglas Fir than from Red Oak
timbers, but both types of wood were readily infested, and generally decomposed within 2-3 years.

8. Commercially available preservatives (e.g., creosote, CCA) retard woodborer infestation. However,
chemical treatments were compromised by cutting the timbers. These cut surfaces exposed untreated
grain which allow woodborers to enter the timbers. At EF and GN, CCA treated timbers with
exposed untreated grain had up to 50% wood-loss in three years.

CONCLUSIONS

Results from these studies indicated that thermal effects due to two unit operation at the Millstone
Nuclear -Power Station were restricted to within 100 m of the effluent discharge point. In future studies,
sustained increase in abundance of Teredo navalis, Balanus eburnens and MytHus edulis or the sustained
decrease in abundance of Balanus crenatus and Laminaria saccharina at nearby sites would indicate thermal
effects caused by three unit operation. In addition. Teredo bartschi recruitment, and establishment of
reproductive populations at sites beyond 100 m from the effluent discharge point would also be considered
power plant related.

40

REFERENCES CITED

Baechler, R.II., B.R. Richards, A. P. Richards and H.G. Roth. 1970. Effectiveness and permanence of
several preservatives in wood coupons exposed to seawater. Am. Wood Preservers' Assoc. 66:47-64.

Barnard, J.L. 1959. Generic partition in the amphipod Family Cheluridae, marine woodborers. Pacific
Naturalist 1:3-12.

Battelle-Columbus Lab., W.F. Clapp Lab., Duxbury, MA. 1978a. Exposure panel variablity study
Millstone. A special report to Northest Utilities Service Company. 13 pp.

. 1978b. A monitoring program on the ecology of the marine envirormient of the Millstone Point,

Connecticut area. Annual report for the year 1978. Presented to Northeast Utilities Service Company.

. 1979. Exposure panel variablity study Millstone. A special report to Northest Utilities Service

Company for the years 1977-1978. 13 pp.

Board, P. A. 1973. The effects of temperature and other factors on the tunnelling of Lyrodus pedicellatus
and Teredo navalis. Pages 797-805 in Proc. 3rd Int. Congr. on Marine Corrosion and Fouling, Natl.
Bur. Std., Gaitherburg, Maryland, U.S.A.

Brown, R.T., and S.F. Moore. 1977. An analysis of exposure panel data collected at Millstone Point
Connecticut. MIT, Cambridge, Massachusetts. Rept. No. MIT-EL 77-015. 119 pp.

Cairns, .1., .Ir. (ed.). 1982. Artificial Substrates. Ann Arbor Science Publisher, Inc. Ann Arbor Michigan.
279 pp.

Cory, R.L. 1967. Epifauna of the Patuxent River Estuary, Maryland, for 1963 and 1964. Chesapeake
Sci. 8:71-89.

41

_, and J.W. Nauman. 1969. Epifauna and thermal additions in the Upper Patuxent River Estuary.

Chesapeake Sci. 10:210-217.

Cravens, J.B. 1981. Thermal effects. J. Water PoUut. Control Fed. 53:949-965.

CuUiney, J.L. 1975. Comparative larval development of the shipworms Bankia gouldi and Teredo
navalis. Mar. Biol. 29:245-251.

Frame, D.W. 1968. Epibiota attached to wooden panels on the Cape Cod Canal, Sandwich, Massa-
chusetts. M.S. Thesis, Univ. of Massachusetts, Amherst, Massachusetts. 146 pp.

Gonzalez, .I.G., and P. Yevich. 1976. Responses of estuarine population of the blue mussel, Mytilus
edulis, to heated water from a steam generating plant. Mar. Biol. 34:177-189.

Grave, B.H. 1928. Natural history of shipworm. Teredo navalis, at Woods Hole Massachusetts. Biol.
BuU. Woods Hole 55:260-282.

Hillman, R.E. 1975. Environment monitoring through the use of exposure panels. Pages 55-76 in S.B.
Saila, ed. Fisheries and energy production: a symposium. D.C. Heath Company. Lexington, Massa-
chusetts.

. 1977. Techniques for monitoring production and growth of fouling organisms at power plant

intakes. Pages 5-9 ij% L.D. Jensen, ed. Biofouling control procedures, technology and ecological effects.
Marcel Dekker, Inc. New York.

Hoagland, K.E. 1981. Life history characteristics and physiological tolerances of Teredo hartschi, a
shipworm introduced into two temperate zone nuclear power plant effluents, [n 3rd Int. Waste Heat
Meetings Proc. 14 pp.

, and R.D. Turner. 1980. Range extensions of teredinids (Shipworms) and polychaeta in the

vicinity of a temperate-zone nuclear generating station. Mar. Biol. 58:55-64.

42

Ibrahim, J.V. 1981. Season of settlement of a number of shipworms (Mollusca: Bivalvia) in six
Australian harbours. Aust. J. Mar. Freshwater Res. 32:591-604.

Imai, T., M. Ilatanaka and R. Sato. 1950. Breeding of marine timber-borer, Teredo navalis L., in tanks
and its use for anti-boring tests. Tohoku J. Agricult. Res. 1:199-208.

Johnson, B.R. 1977. Preformance of single- and dual-treated panels in a semi-tropical harbor. Am.
Wood Preservers' Assoc. Prog. Rpt. 73:174-180.

, and D.I. Gutzmer. 1981. Marine exposure of preservative-treated small wood panels. U.S. Dept.

of Agri., Forest Service, Forest Products Lab., Research Paper, FPL 399. 14 pp.

Johnson, G., J. Foertch, M. Keser, and B.R. Johnson. 1983. Thermal backwash as a method of
macrofouling control at Millstone Nuclear Power Station, Waterford, CT, USA. Section 25 in I.A.
Diaz-Tous, M.J. Miller, and Y.G. Mussalli (eds.). Symposium on Condenser Macrofouling Control
Technologies - The State of the Art, June 1-3, 1983. Hyannis, MA.

Maciolek- Blake, N.J., R.E. Hillman, P.I. Feder and C.I. Bellmore. 1981. Annual report for the period
December 1, 1979 to November 30, 1980 on study of woodborer populations in relation to the Oyster
Creek Generating Station to Jersey Central Power and Light Company. Battelle-William F. Clapp
Laboratories. Report No. 15040. 15 pp.

Manyak, D.M. 1982. A device for the collection and study of wood-boring molluscs: application to
boring rates and boring movements of the shipworm, Bankia gouldi. Estuaries 5:224-229.

NAI (Normandeau Associates, Inc.). 1979. Seabrook Ecological Studies 1976-1977. Estuarine panel
studies. Coastal panel studies. Tech. Rept. VII-5: 311-436. Prepared for Public Service Compoany of
New Hampshire.

Nair, N.B. and M. Saraswathy. 1971. The biology of wood-boring teredinid molluscs. Adv. Mar. Biol.
9:335-509.

43

Nauman, J.W., and R.L. Cory. 1969. Thermal additions and epifaunal organisms at Chalk Point,
Maryland. Chesapeake Sci. 10:218-226.

Naylor, E. 1965. Effects of heated effluents upon marine and estuarine organisms. Adv. Mar. Biol. 3:63-103.

NUSCo (Northeast Utilities Service Company). 1982. Monitoring the marine environment of Long
Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Annual report, 1981.

. 1983. Exposure Panels 1968-1981: A review and evaluation. Monitoring the marine environment

of Long Island Sound at Millstone Nuclear Power Station, Waterford, Connecticut. Resume 1968-1981.
37 pp.

Osman, R.W. 1977. The establishment and development of a marine epifaunal community. Ecol.
Monogr. 47:37-63.

. 1978. The influences of seasonality and stability on the species equlibrium. Ecology 59:383-399.

, R.W. Day, .I.A. Haugsness, J. Deacon and C. Mann. 1981. The effects of the San Onofre Nuclear

Generating Station on sessile invertebrate communities inhabiting hard substrata (including experimental
panels). Hard Benthos Project, Marine Science Institute University of California, Santa Barbara. Final
Report 223 pp.

Richards, B.R. 1977. Comparative values of dual-treatment and water borne preservatives for long-range
protection of wooden structures from marine borers. Am. Wood Preservers' Assoc. 73:128-130.

. 1979. Comparative values of dual-treatment and water borne preservatives for long-range pro-
tection of wooden structures from marine borers. As submitted to American Wood Preservers Institute,
Battelle-Wm. F. Clapp Laboratories. Duxbury, Massachusetts. Rept. No. 14951. 23 pp.

Scheltema, R.S. and R.V. Truitt. 1956. The shipworm Teredo navalis in Maryland coastal waters.
Ecology 37 (4). 3 pp.

44

Schoener, A. 1974. Experimental zoogeography: colonization of marine mini-islands. Am. Nat.
108:715-738.

Shafto, S.S. 1974. The marine boring and fouling invertebrate community of Bamegat Bay, New Jersey;
general community structure: the relationship of hydrography to dominant species and community
complexity; specific community structure: patterns of differential settling of dominant species as a
function of depth and surface orientation. M.S. Thesis, Rutgers Univ., New Brunswick, New Jersey.
237 pp.

Sutherland, J. P., and R.H. Karlson. 1977. Development of stability of the fouling community at
Beaufort, North Carolina. Ecol. Monogr. 47:425-446.

Turner, R.D. 1947. Collecting shipworms. Limnol. Soc. Am. Spec. Publ. No. 19.

. 1966. A survey and illustrated catalogue of the Teredinidae. Cambridge Mus. Comp. Zool.

Hcirvard Univ. 265 pp.

. 1973. In the path of a warm saline effluent. Am. Malacol. Union Bull. 39:36-41.

Weiss, CM. 1948. An observation on the inhibition of marine wood destroyers by heavy fouling
accumulation. Ecology 29:120.

Young, J.S., and A.B. Frame. 1976. Some effects of power plant effluent on estuarine epibenthic
organisms. Int. Revue, ges. Hydrobiol. 61:37-61.

Zobell, C.E., and E.C. Allen. 1935. The significance of marine bacteria in fouling of submerged surfaces.
J. Bacteriology 29:239-251.

45

Contents

FISH nCOLOGY 1

IN'IRODUCTION 1

MATERIALS AND MEIHODS 4

Ichthyoplankton program 4

Impingement program 8

Trawl program 10

Seine program 12

Data handling 16

Time-series analysis 18

RESULTS AND DISCUSSION 20

Ichthyoplankton 21

Impingement 26

Trawls 27

Seines 28

Selected species 30

Ammodytes americanus, American sand lance 30

Anchoa spp., anchovies 32

Gasterosteux spp., sticklebacks 36

Menidia spp., silvcrsides 38

Microgadus lomcod, Atlantic tomcod 39

Myoxocephabis aenaeus, grubby 44

Tautoga onilis, tautog 46

Tautogolahrux adspersus, cunncr 51

C:ONCLL'SIONS 56

SUMMARY 57 •

REFERENCES CITED 58

AFPENDIX 68

FISH ECOLOGY
INTRODUCTION

Finfish are an important marine resource and are found in a variety of habitats in the vicinity of
Millstone Nuclear Power Station (MNPS) in eastern Ixjng Island Sound (LIS). The construction and
operation of MNPS could affect fish assemblages inhabiting the site environs (Fig. 1) by increasing
mortality rates of various life stages and by altering spatial distributions. Populations may experience
higher than normal mortality rates due to either impingement of young and adult fish on the intake screens,
or entrainment of larvae in the cooling water system. The effect of increased mortality rates on these
populations can be very different depending on the size, age structure and life span of the affected
populations, and on the existence of compensatory mechanisms. Further, the spatial distribution of local
fish populations may change in response to alterations in the thermal or chemical regime of the effluent
or modifications to the physical habitat. Warmer water temperature can attract or exclude fish from areas
affected by the thermal plume. Physical alterations caused by construction, dredging or bottom scouring
could also attract or exclude fish from affected habitats. Because of these potential effects, Northeast
Utilities Service Company (NUSCo) established several finfish sampling programs to provide baseline data
for assessing the impacts of construction and operation of MNPS on local fish populations.

The objectives of the fish ecology programs are as follows:

1. To sample, identify, and enumerate fish found in the Millstone Point area;

2. To determine which fish species may be susceptible to impact from entrainment, impingement, or
exposure to the heated effluent; and

3. To describe the fluctuations in abundance of life history stages of species that are potentially impacted
and evaluate whether these fluctuations are within the expected historical range or have been effected
by power plant operation.

Long Island Sound

Figure 1. F^ocation of the Millstone Nuclear Power Station in eastern Long Island Sound.

To meet these objectives the available life history stages of local finfish species are studied by various
programs at Northeast Utilities Environmental Laboratory (NUEL). The sampling programs established
over the years to monitor planktonic, demersal, pelagic and shore-zone fish abundances, were complemented
by entrainment and impingement monitoring programs. Studies of planktonic fish eggs and larvae (i.e.,
ichthyoplankton) have been conducted at Millstone since 1973. TTiese studies have included entrainment
and offshore collections at various stations, and entrainment mortality and thermal tolerance studies on
selected larval fish species. A trawl sampling program was established in April 1973 to monitor demersal
fish. Since then, up to 11 stations have been sampled biweekly. Although the program has been reduced
to six representative sites, the methodology continues today relatively unchanged. The seine program,
established in 1969 to monitor shore-zone fish, involved sampling at up to 7 stations at various frequencies.
This program has been reduced to three representative sites, but the methodology remains unchanged.
Routine impingement sampling began at MNPS Unit 1 in 1972, and at Unit 2 in September 1975.

Monitoring at Unit 1 ceased with the installation of a fish return system in 1983. A gill-net program was
established in 1971 to monitor pelagic fishes that were not caught in the trawl or seine programs, but it
was discontinued in 1982 after an evaluation concluded that the gill-net program did not provide qualitative
data, was not cost effective, and did not sample potentially impacted fish (see Appendices la and lb and
NUSCo 1982c).

The monitoring studies were supplemented over the years by several entrainment survival and fish
diversion studies, and by an evaluation of the Unit 1 fish return (sluiceway) system. Special studies of
mortality experienced by fish larvae during entrainment and the thermal tolerance of selected species were
conducted (Carpenter 1975; NUSCo 1975). Mortality of larvae entrained through Unit 1 was estimated
to range from 20 to 50%. I^arvae were captured at the intake, discharge and quarry cut and held for 24
hr at intake water temperatures. Laboratory thermal tolerance studies, conducted on larvae of the silverside
(Menidia spp.) mummichog (Fundulm spp.) and winter flounder {Pseudopkuronectes americanm) to assess
thermal effects of power plant entrainment, indicated that mortality was low for silversides and mummichogs.
The application of several devices (electric screens, noise generator, underwater lights, surface and bottom
barriers and barrier nets) was investigated in an attempt to divert fish from the intakes and reduce
impingement. Of the different devices tested, none reduced impingeftient (NUSCo 1976b). In 1980,
NUSCo (1981b) demonstrated that it was practical and cost-effective to backfit a fish return system at
Unit 1. A sluiceway was fabricated and installed there in December 1983, and results from a subsequent
study indicated that survival of demersal fish and non-molting crustaceans exceeded 70% (NUSCo 1986b).
Because the Unit 1 sluiceway has worked as designed and has successfully returned most organisms to
LIS, it has mitigated the impact of impingement.

This report summarizes the monitoring data gathered by the ichthyoplankton, trawl, seine, and
impingement programs during the period of two-unit operation, 1976 through 1985. Accounts of the
evolution of these programs are also provided. In addition, the monitoring data and life history of eight
potentially impacted fish species are presented and evaluated to determine if two-unit operation of MNPS
has had any detrimental effect on them. Finally, it is noted that the monitoring data summarized in this
report consitute the baseline against which three-unit operational data will be compared after 1986.

MATERIALS AND METHODS

Ichthyoplankton program

Ichthyoplankton studies have been conducted at Millstone since 1973. The program consisted of
both "offshore" and "entrainment" sampling, and the number of samples collected by year and station is
summarized in Appendix II.

Offshore sampling was initiated in 1973 to provide information for development and interpretation
of entrainment impact predictive models (Sissenwine et al. 1973). A bongo sampler with two conical
plankton nets of 0.333- and 0.505-mm mesh and weighted with a depressor was towed for 1.5 min. Various
combinations of 16 stations (Fig. 2), sampling frequencies (weekly, biweekly, monthly), tow types (surface,
sawtooth oblique, bottom), and times (day, night) were used (Battelle 1976) (Table 1). Following an
evaluation of the program in 1975 (Vaughan et al. 1976), offshore sampling was redirected towards
determining the densities and seasonal succession of the plankton cornmunity. The number of stations
was reduced to six, the sampling frequency was changed to monthly, and night sampling was eliminated.
llie program was evaluated again in 1978 and the resulting recommendations were implemented in 1979.
Sampling was limited to NB because this station provided the most representative samples of the offshore
plankton community (NUSCo 1978). The 0.505-mm mesh net on one of the bongos was replaced with
a 0.333-mm mesh net; this arrangement provided replication for the latter net. A stepped oblique tow (5
min each at surface, bottom, and mid-depth) provided a sample representative of the entire water column.
Night sampling was reinstated to investigate the response of ichthyoplankton abundance to the diel period.
The program has essentially remained unchanged since 1980, except for the use of a wire angle-indicator
to more accurately position the net at the mid and bottom water depths.

The ichthyoplankton entrainment studies began in 1973 (Table 2). The density of fish eggs and
larvae was estimated from three replicate samples collected at the intake (IN) at three depths: surface (in
previous reports called INTl), mid (previously INT3) and bottom (previously INT5), at the discharge
(FN, previously DISI), and at the quarry cut (QCUT) (Fig. 3). Thirty plankton samples were taken every
week (15 day, 15 night) with a 1.0 x 3.6-m conical plankton net with 0.333-rrun mesh netting; the volume

Figure 2. Location of the ofTshore plankton sampling stations.

of water sampled was estimated from a TSK flowmeter. During 1974, studies were conducted to compare
the catches from the 0.333-mm mesh offshore sampling net and the net used at EN, and to evaluate
laboratory processing techniques. Results indicated that there was no significant difference between the
abilities of the two nets to catch eggs or larvae nor in the techniques used to process the samples (NUSCo
1983). Beginning in .luly 1975, an electronic flowmeter was used to measure volume of entrainment
samples. Sampling was limited to the discharge station, where flow velocities were high cnougli to eliminate
problems of poor flowrrieter response and net avoidance. Although the exact location of this station was
somewhat different from that used previously, a comparability study revealed that there were no significant
differences among density estimates made from samples collected simultaneously at the two sampling
locations at the discharge (NUSCo 1976a). The sampling frequency was changed from one-day and
one-night set of samples per week to three days and three nights per week (three replicates each, for a

Table I. Summary of ofTshore plankton sampling program.

J 1 r I M 1 A

M 1 J 1 J 1 A 1 S

1 O 1 N 1 D

1973

Stations 1-4, 6-10 & NR sampled " Week

ly (day) and Monthly (nighl)

1974

As in
Dec.

197,3

Stations 1-4, 6-13 & NR sampled"

Weekly (day) and Monthly (night)

Stations 1-4, 6-16 &
NB sampled^

1975

Weekly (day)
Monthly (night)

Stations 1-4, 6-16 & NB sampled "

Biweekly (day)
Monthly (night)

Monthly
(day and night)

1976

As in
Dec.

1975

Stations 2, 6, 8, 11, 14 & NB sampled"
Monthly (day only)

1977

to
1978

1979

to

Present

n

(day

ivveekly
and night)

Station NB sampled
At least weekly
(day and night)

Biweekly
(day and night)

' Sample technique - one 15-min sawtooth oblique towusing a bongo frame rigged with 0.333-mm mesh and n.SOS-mm mesh
plankton nets. Station NB previously reported as station 5.

Same as "a", but replicate stratified (surface and bottom) and oblique tows were also done on a regular basis at randomly
selected stations (see Battelle 1976 for details).

In 1979 towing methodology consisted of 15-min sawtooth oblique tows using a bongo frame rigged with two n.333-mm
mesh plankton nets. Beginning in 1980 the methodology changed to a stepped oblique tow (5 min lop, 5 min mid-depth, 5
min at bottom), f-rom 1983 to present a wire angle-indicator was u.sed to accurately position the net at surface, mid and
bottom.

total of 18 samples per week) to improve the accuracy of den.sily estimates and increase the sensitivity of
subsequent analy.ses. When Unit 2 began using cooling water (fall 1976), sampling at l',N began alternating
weekly between the discharge structures of Units 1 and 2, when operating conditions permitted. I'he
electronic flowmeter was replaced with an array of four General Oceanics flowmeters in 1080. The bases
for replacing the electronic flowmeter were high cost, poor maintenance record, and inability to account
for vertical and horizontal differences in flow observed at the discharges of the two Units (NUSCo 198.^).
The program was reviewed several more times (NUSCo 1981a, 1983, 1984a) and the sampling frequency
reduced according to the schedule in Table 2. The evaluation of these sampling schedules (NUSC'o 198.^)
indicated that no appreciable loss of accuracy had occurred despite a reduction in effort (see Appendix H).

Millstone Nuclear Power Station

Niantic
Bay

Figure 3. Location of the entrainment sampling sites.

The current ichthyoplankton sampling program includes weekly or biweekly collections at station
NB (located in mid-Niantic Bay) and at least weekly collections at station EN. Samples at NB were taken
with the bongo system described previously using 0.333-mm mesh nets. Sampling duration was 5 min at
each depth (surface, mid, and bottom) in stepwise oblique tows. Sample volumes were estimated using
one General Oceanics flowmeter in each net. Approximately 300 m of seawater were filtered in each NB
sample. Samples at EN were collected with the 1.0 x 3.6-m, 0.333-mm mesh conical plankton net deployed
for 4 to 10 min on a gantry system. The deployment time depended on plant operating conditions and
it was adjusted to filter about 400 m of cooling water per sample. Four General Oceanics flowmeters
were positioned in the mouth of the net to record flow. Volume sampled was calculated by averaging the
volume estimates provided by the four flowmeters. All offshore and entrainment samples were preserved
in a 5 to 10% formalin solution.

Although there have been minor changes in laboratory techniques to improve efficiency, the basic
process has remained consistent. A dissecting microscope was set at 1 0 or 1 2 X magnification to view a
portion of the sample and fish eggs and larvae were counted or removed using forceps. Initially, all fish

Table 2.

Summary of entrainmcnt plankton sampling program, 1973 - 1985.

J 1 r- 1 M 1 A

m|j |J |a|s |o|n|d

IQVf

.3 reps taken one day and one night per week at
IN(surrace, mid & bottom). EN & QCUT

1974

.3 reps taken one day and one night per week at IN(surrace, mid & bottom), EN & QCUC

1975

.3 reps taken one day and one night per week at
IN(!;urrace, mid & bottom), EN & QCUT

3 reps taken 3 days and 3 nights per week
at EN

1976 to
19S0

3 reps" taken 3 days and 3 nights per week at EN

1981 to
1982

i reps taken .1 days and .3 nights per week at EN

3 reps taken 1 day and 1
night per week at EN

198.1 to
1984

1 rep taken 4 days and 4 nights per vvcek at EN

1 rep taken 1 day and 1
night per week at EN

1985

I rep taken 1 day

and 1 night per

week at EN

1 rep taken 4 days and 4
nights per week at EN

1 rep taken 3 days and 3 nights per
week at EN

I rep taken 1 day and 1
night per week at EN

Volume estimated from TSK flowmeter readings
Volume estimated from electronic flowmeter
Volume estimated from General Oceanics flowmeter

larvae were removed from whole samples and identified to lowest practical taxon. Fish eggs were identified
year-round beginning in May of 1979 and from only April through September from 1981 through the
present. As the technology became available, a splitter (NOAA-noume, described by Botelho and Donnely
1978) was developed that allowed accurate subsampling and reduced .sorting time. Successive subsamples
were processed until at least 50 larvae and 50 eggs (for samples processed for eggs) were found, or until
one-half of the sample was examined. Samples collected at EN were sorted for both fish eggs and larvae,
but NB samples were sorted for larvae only (see Appendices III and IV). This further reduced laboratory'
processing time, but resulted in only minimal loss of infonnation (NUSCo 1983). Gunner [Taulo^olahrus
adsper.ws) and tautog (Tautoga onitis) eggs were differentiated weekly using the criterion of bimodality of
egg diameters (Williams 1967). Ichthyoplankton density was expressed as numbers per 500 m .

Impingement program

Fish impinged on the 9.5-mm mesh intake screens at Units 1 and 2 were periodically washed into
perforated collection baskets. Screens wash at various intervals, depending upon debris loading, and

frequency ranges from continuous washing during storms to at least once every 8 h. Impingement samples
were taken by sorting fish from all the material washed from the screens during a 24-h period, usually
beginning and ending at about 0800. Fish were identified to the lowest possible taxon, counted, and up
to 50 specimens of each species were measured to the nearest mm in total length, (ilatch was recorded as
number impinged per 24-h period.

Routine impingement sampling began at Unit 1 in 1972, although some qualitative observations were
made as early as 1971. Sampling at Unit 2 was initiated in September 1975. The primary objective of
impingement monitoring at Millstone has been to quantify total annual species-specific mortality. Ways
of minimizing this mortality were evaluated and plant design changes were recommended when appropiate.
Throughout the 13 yr of monitoring, various changes have been implemented. These occurred mainly in
four major areas, including the frequency of daily counts, the way in which fish lengths were recorded,
the method used to estimate the number of fish impinged per 24-h period, and the elimination of
impingement monitoring at Unit 1 after 16 December 1983 when a fish return sluiceway was installed.

Changes in the frequency of impingement monitoring are outlined in Table 3. From 1972 to March
1977, impinged organisms accumulated over a 24-h period and were counted daily. In 1977, sampling
effort was reduced to 3 counts/week. Before this reduction, mean daily impingement estimates for each
month based on 7 counts/week were compared to mean daily estimates extrapolated from 3 counts/week.
The differences between actual monthly totals based on a complete census and the estimated totals ranged
from 20 to 50%, depending upon the species (NUSCo 1978). At the level of effort reduced to 3
counts/week, more than 85% of all species were represented. In 1982, the impingement program was
evaluated to determine if the precision of the impingement data could be improved by redistributing and
optimizing effort (NUSCo 1983). Historical data (3 counts/week) were stratified by month and effort and
reallocated according to Fl-Shamy (1979). The historical program (uniform effort - 3 counts/week) had
a precision value of 0.79. When the sampling effort was hypothetically redistributed so that more samples
were collected in those months when the variances of winter flounder [Pseudopleuronextes americanm)
counts were high and fewer samples in months when variances were low, the precision factor increased to
0.88. An optimal sampling scheme was implemented in December 1983 (Table 3). Since then, sampling
effort at Unit 2 was stratified by month so that 8 samples were collected in .lanuary, 15 in February, 14
in March, 5 in April, 4 per month from May through November, and 10 in December. The overall
sampling effort was reduced by approximately 40%.

Table 3. Summary of impingement collections made per week. Unit 1 impingement collections were made from 1971, when it
first became operational, through 1983. Impingement collections at Unit 2 were made from the time it became operational (1976)
to the present.

J

F

1 M

^

1 M 1 J 1 J 1

-

S

o

N

I.)

1971 to 1972

Irregular sampling

1973 to 1976

7 24-h samples collected per

week.

1977 to 1983

3 24-h samples collected per

week.

1984 lo dale

2

^

3

'^

1 ' 1 > 1 ' 1

■ 1

1

'

•

1 ^"

If necessary, additional samples were taken to ensure that 5 samples were collected during April.

If necessary, additional samples were taken to ensure that 10 samples were collected during December.

During the first 3 yr of impingement monitoring (1972-1974), lengths of all fish impinged were
recorded. From January 1973 to April 1975, length information was recorded for each species by categories:
less than 3 in, 3 to 6 in, and greater than 6 in. This method did not accurately describe the sizes of
various species and was discontinued. In May 1975, the present practice of measuring up to 50 individuals
per sample was instituted. However, in 1977 and 1978, 100 or more individual lengths per species were
recorded. Fifty measurements per sampling date for each of five taxa (winter flounder, silversides, thrcespine
stickleback, grubby, and long-fmned squid) were randomly selected from the data base. The resulting
length frequency distributions were compared to the entire distributions for each species using chi-square
goodness-of-fit tests. For all five species, the random length distributions with 50 measurements were not
significantly different (p > 0.98) from the original distribution (NUSCo 1983).

Trawl program

The trawl sampling program was established in April 1973 to monitor demersal fish. Throughout
the program, demersal fish were sampled using a 9.1-m otter trawl with a 0.6-cm codend liner. Initially,
one 15-min haul was made biweekly at each of seven stations, including 1, 4, .IC (previously called station
6), 7, IT (previously station 8), 9 and 10 (Fig. 4). In September 1974, station IN (previously station 11)
was added because it was a potential location for the Unit 3 intake. In February 1975, station NB
(previously station 5) was added to provide a more representative sample from Niantic Bay. Sampling
began at station NR (previously station 2, then N2) in June of 1975 to obtain infonnation on fish
communities in the lower Niantic River. In February 1976, station BR (previously station 14) was added

10

Figure 4. Location of the trawling sampling stations.

because the area was considered another potential site for the Unit 3 intake. Single and duplicate tows
were made at various sites from 1973 to 1976 and are outlined in Table 4 along with a summary of the
addition and deletion of sampling stations. Several stations were eliminated in 1976: stations 1, 7, and 10
because the bottom cover made trawling inefficient; station 4 because it was similar to NB; and station 9
because it was very close to BR. Since February 1976, triplicate tows have been made biweekly at NR
(Niantic River), NB (Niantic Bay), JC (Jordan Cove), TT (Twotree), IN (Intake), and BR (Bartlett Reef).
These six stations are believed to represent the different demersal environments surrounding Millstone Point.

In October 1977, the unit of trawl effort was changed from 15 min to 0.69 km over the bottom
because it was felt that demersal fish abundance would be better estimated using a unit of effort based on
the area swept. The distance 0.69 km was used because it was the maximum distance that could be
covered at JC. This distance also provided some continuity with previous data because it approximated

the length covered in 15 min when the boat was towing a trawl under average conditions, with the engine
at idle speed and not influenced by tidal currents. Up to 50 individuals of a taxon at each station were
measured (total length) to the nearest millimeter. Catch was expressed as number of fish per standardized
tow.

Table 4. Summary of trawl sampling program. The .station numbers correspond to the stations listed in Figure 4. All stations
were sampled biweekly with a 9.1-m Wilcox otter trawl. Stations: I - Llpper Niantic River; NR -^ lower Niantic River; 4 -
Crescent Beach; Nil ^ Niantic Bay; JC == Jordan Cove; 7 " Seaside; 7T Twotrce; 9 -- Black Point; 10 - Otiler Bartlelt
Reef; IN ^ Intake; BR = Bartlett Reef.

J

F

ivi|a|m|j |j |a|s |o|n|d

197.3

Stations 1,4,7,9,10,JC & TT — One 15-min tow at each station.

Stations 1, 4, 7, 9, 10, JC & Vr:

Sta. I, 4, 7, 9, 10,

JC, TT & IN:

Two lows at TT, 10, IN;

One tow elsewhere.

Two tows

3 tows

1974

one 1 5-min tow

at one

at one

at each.

station.

sla.

One 15-min tow at other stations.

As in

Stations

Stations

197.S

Dec.

1974

1, 4, 7, 9, 10, JC, TT, NB, IN

1,4, 7, 9, 10, JC, NB, TT, IN & NR:

Two 15-min tows at Station 10, NB, TV. IN and one random station; one tow elsewhere.

As in

Stations 1, 4, 7, 9, 10, JC, TT, NB, IN, NR, BR:

1976

Dec.

Three 15-min lows at JC, NB, IT', IN, NR, BR;

1975

one 15-min tow elsewhere

Stations JC, IT', NB, IN, NR, BR: three tows at each station.

1977

(15-min) | (0.69 km over bottom)

1978 lo

Stations JC, TT, NB, IN, NR, BR — Three tows at each station

present

(0.69 km over bottom)

This station was selected randomly.

Seine program

The seine sampling program, established in 1969 to monitor shore-zone fish, is summarized in Table
5. Shore-zone fishes were sampled using a 9.1 x 1.2-m knotlcss nylon seine net of 0.6-cm mesh hauled
parallel to the beach for about 30 m; three replicates were taken in adjacent areas of the beach. Because
a preliminary study (I3atteilc 1973) indicated that there was no difference in the numbers offish collected

12

from the shore-zone at different tidal stages, all collections were made in the 2 h before high tide. The
shore-7one fish assemblages of seven different areas were sampled at some point in time since May 1969.
These areas were GN (Giants Neck), BL (Black Point), SP (Sandy Point in the Niantic River), IN (Bay
Point in front of the station intakes), JC (Jordan Cove), WP (White Point), and SS (Seaside) (Fig. 5).
From 1969 through 1972, stations GN, IN, JC, and WP were sampled. In February 1973, SS and BL
were added. Station SP was sampled in only 1975. Sampling at IN was discontinued in 1983 when
construction activities associated with the Unit 3 intake removed a major portion of the beach. Sampling
at BL was also discontinued in 1983 because its bottom type did not correspond to other stations and
because few fish were caught there. Catches of shore-zone fish at SS also did not correlate with catches
at other stations, probably because the station was more exposed to wind and wave action than the others
(NUSCo 1983). Sampling at SS was discontinued in 1984 and effort was redistributed to the special seine
study described below. Initially, hauls were made in February, May, July, September, and December; this
frequency continued through 1973. In 1974, sampling frequency was increased to include collections
during June, August, and October. Collections in November were added in 1982 and in .lanuary during
1984. Also, in 1984 sarrnle frequency was increased to biweekly from April through October.

Figure 5. Location of the shore-zone seine sampling stations.

13

Throughdut the sampling program, fish were identified to lowest practical taxon and measured to
the nearest millimeter in length. From 1969 to 1980, standard length was measured. During J9S1-J982,
both standard and total lengths were measured and a regression was used to convert previously recorded
standard lengths to total lengths (NUSCo 1984a). When more than 50 individuals of a taxon were collected
in a replicate, a representative subsample was measured; otherwise all fish were measured. Catch was
expressed as number of fish per 30 m haul.

Special seine study. In 1982, the seine program was evaluated to determine if it would adequately
address the potential impact of the three-unit thermal plume. The sampling frequency was increased to
biweekly from April through October to achieve a 50% detectability level for the dominant shore-zone
taxon, the silverside. MacCall et al. (1983) recommended this level as a criterion for long-term impact
a.ssessment programs. Because the thermal plume was projected to encompass .Jordan (\)ve and raise the
water temperature 0.3°C on the flood tide and 1.2''C on the ebb, sampling was scheduled for both tidal
stages from April through October, when most fish are in the shore zone. Initially (April-.Iuly 1984),

Table !>. Summary of seine sampling program during 1969-1985. Three seine hauls were made with a 9.1-m, 0.fi,')-cm mesh seine
net at each station (see Figure 5). Unless otherwise indicated, all samples were collected during the 2-h period prccccding high tide.

J 1 F

M 1 A

M

J

J

A

S

O

N

U

1969

GN WP
IN JC

GN WP
IN JC

GN WP
IN JC

GN WP
IN JC

1970 to
1972

GN WP
IN JC

GN WP
IN JC

GN WP
IN JC

GN WP
IN JC

GN WP
IN JC

197.1

GN WP
IN JC
SS BL

GN WP
IN JC
SS BL

GN WP
IN JC
SS BL

GN WP
IN JC
SS BL

GN WP
IN .IC
SS BL

1974

to
1982'

GN WP

IN JC
SS BL

GN, WP, IN, JC, SS, RL Monthly

GN WP
IN JC
SS Bl,

198.1

GN WP
IN JC
SS Bl.

GN, WP.JC, SS Monthly

1984

ON. ,IC, WP, SS

Monthly

^

GN, WP-- Biweekly, High 1 Rbb

SS-- Monthly, High
JC- Biweekly High, Monthly Ebb

GN, WP. SS, JC

Monthly

1985

GN WP JC Mc

)nthly

GN WP .- Biweekly, High ( Ebb
JC - Monthly, High H Rbb

GN WP JC
Monthly

Ouring
During

1975 only one haul was made at IN, three hauls were made at SP.

this time period, JC and WP were sampled biweekly, high I ebb; GN and SS were sampled monthly, h

Rh.

14

stations .K' and WP were sampled biweekly on both tides. Both sites are within the area projected to be
influenced by the thermal discharge from three-unit operation. But because only 2 yr of 3-unit pre-operational
data could be collected on the ebb tide, a new sampling scheme was adopted based on a control-treatment
pairing (CrrP) design (Skalski and McKenzie 1982; Bernstein and Zalinski 1983). The critical requirement
of the CTP design is the selection of the control-treatment (nonimpacted-impacted) pairs of stations where
the abundance of an organism responds similarly to changes in environmental parameters. The ratios of
control-to-treatment data from each pair of stations, are compared between pre-operational and operational
phases to detect impacts. An analysis of 15 yr of data showed significant correlations between GN (control)
and WP (treatment) data using silverside and total fish abundance as response variables. Based on the
results of this analysis, a new sampling scheme was adopted. Our control-treatment pair (GN, WP) is
now sampled biweekly. Because work to date will serve as a baseline for a future assessment of three-unit
operation, no data from this special study are presented here.

Data handling

To assess impacts it was necessary to identify potentially affected species, document their spatial
distribution, and describe the natural temporal fluctuations of their life history stages collected near MNPS.
Although sampling at NUEL has occurred since 1969, the changes in each program have limited the
comparability and usefulness of data collected before 1976. Therefore, when data were available, analyses
were restricted to 1976-1985, the period of two-unit operation at MNPS. The only exception to this was
that the 1969 through 1985 seine data were used in the time-series analysis of silversides.

The selection of potentially affected species was based on their prevalence in entrainment or
impingement samples. Spatial distribution patterns were based on the catch of a species at each station.
Temporal fluctuations were described by annual (median and/or mean) catches and by the forecasts pro-
vided by time-scries models, which used log-transformed catch data. The distribution of life history stages
in impingement, trawl, and seine collections was inferred from the morphological characteristics and sizes
of the fish. Identification of each fish species in all programs was made to the lowest possible taxon.
Some specimens were identified to genus or family if they were juveniles, adults that could not be easily
identified in the field, or if they were species of uncertain taxonomic status due to inadequate descriptions
in the literature. The taxa which included more than one species are listed in Table 6. This table also
includes the programs in which each taxon was used, the reason for combining species, and the probable
species that were included in each group identification.

15

Table ft. List of taxa which were identified to genus or family.

Taxa

Program

Reason Possible identification

Alona spp.

PL,I,T

1, 2 ,.1,4

Anchoa spp.

PL..I,T.S

1,2,.-?

Rothidae

PI.,'f

3,5

Clupeidae

PI„I,T,S

1,4

Fundulus spp.

PL.I T,S

3

Gadidae

PI.,I,T,S

2.3

Gasterostcidae

PL,I,T

3

Gobiidae

PL,T

3

Ijpam spp. PL.l.T

Me.nidia spp. PL,I,T,S

\fyoxorpphalu!! spp. PI.,I,T

rrinnotin: spp. P[.,,I,T,S

Sciaenidae PI..,I,T

Urophych spp.
Raja spp.

PL.I.T.S
I,T

1,3

1,2,3

2,3

3

2,5

1,2,3

Alosa aeslivalis, Alo!:a mediocrh, Alosa pseudoharengus, Alosa <;apidissima

Anchoa hepSRtus, Anchoa mitchilU

Bothus ocellatu.i, l.eft-eycd flounder

Brevoorlia tyrannus, Clupea harengus, Alosa spp.

Fundulm majalis, Fundulus heteroclitus

Enchelyopus cimbrius, Gadus morhua, Mkrogadus lomcod, Pollachius virms

Apeltes quadracus, Gasleroslpus aculeatus, Gasterosteus wheallandi,

rungiiius pungilius

Goblonellus botensoma, Mirrogobius thalassinnus, Gobiosoma bosci,

Gobiosoma ginsburgi

Liparis allantiais, Uparis liparis

Menidia beryUina, Menidia menidia

Myoxocephaius aenams, Myoxocephalus oclodecemspinosus

Prionotus carolinw:, Prionotns evolans

Rairdinlla chrysnura, Cynoscion regalis, JMostomus xanlhiirus,

Menticirrhus saxarilis

IJrophycis chuss, Urophych rcgia, Urophycis tenuis

Raja erinacea, Raja ocellata

Program: PI, " plankton (larval), I = impingement, T "' trawls, S - .seines

Reason: 1 - Dirficult to identify using external features; 2 ^ Juveniles similar; 3 - Incorrect identincalion may have occurred;
4 ~ literature is not clear at species level; 5^ Too few collected for exact identification.

Ichthyoplankton abundance estimates. Because the tchthyoplankton data collected had skewed distri-
butions, median rather than arithmetic densities (no./500 m ) of the most abundant icthyoplankton taxa
entrained (station EN) were used to describe temporal trends. These medians, also used for calculating
entrainment estimates, were determined from data collected during the period when each species occurred
annually. The period of occurrence was that time during which 95% of the annual cumulative abundance
occurred; the data falling in the two tails (2.5% each) of the cumulative frequency distribution were not
used to compute the medians. Median densities could not be calculated for any taxon that had many
zero observations within its annual period of occurrence because the resulting median would have been at
or near zero. Therefore, arithmetic mean densities (no./500 m ) were computed and used as an index of
relative abundance to rank all the species in the species list tables. Similarly, annual mean densities were
used to determine annual cumulative densities for the six most abundant taxa of ichthyoplankton.

16

En<rainiticnt estimates. Annual entrainment estimates for selected species of larvae were calculated
from 1976 through 1985 and for eggs from 1979 through 1985. These estimates were obtained by
multiplying the median density at FN during the period when 95% of the annual cumulative abundance
occurred times the total volume of water passed through MNPS during the same period. A nonparametric
method (Snedecor and Cochran 1967) was used to construct a 95% confidence interval around each
median density and corresponding entrainment estimate.

Impingement estimates. Historically, several methods were used to estimate impingement when counts
were no longer made daily after April 1977. The first method used the real-time to sample-time ratio to
obtain estimates. Beginning in 1979, monthly impingement estimates were based on the extrapolation of
actual counts using a volumetric ratio. The daily cooling-water volume was calculated based on 15 min
flow rates from 0000 to 2345 for the date on which the impingement sample was taken during the morning.
This flow rate was then lagged back one day before it was used in the estimation procedure. The present
estimation procedure was developed in 1985 to account for the fact that impingement rates are directly
influenced by cooling water flow (Con Ed and PASNY 1977; lawler, Matusky and Skelly Engineers 1980).
Cooling-water volume estimates corresponding to the actual 24-h impingement period (0800 to 0745) of
each sample were used in order to improve accuracy. Within each monfh, an estimate for every day not
sampled was calculated by multiplying the average impingement density (number of fish per m of cooling
water) based on the days sampled in that month times the volume of cooling water on each day not
sampled. All of these daily estimates were then added to the sum of the actual sample counts to arrive
at the monthly totals for each species. Annual impingement estimates were calculated by summing the
monthly estimates.

Fish length frequency data. As indicated previously, sampling effort was stratified by season for seine
sampling and by month for impingement sampling during some periods of the study. Therefore, whenever
appropriate, the length-frequency data were weighted to account for unequal effort during the year. Because
seine sampling effort from April through October was twice that during the remainder of the year, data
collected from November through March were weighted by a factor of two. For impingement collections,
monthly weight factors of 4 (.January), 2 (February and March, 6 (April), 7 (May through November),
and 3 (December) were used to standardize monthly effort close to 30 (range of 28 to 32).

17

Time-series analysis

Autoregressive integrated moving average (ARIMA) time-series models were developed to describe
the natural fluctuations of potentially impacted species in the MNPS area during the period spanned by
our baseline data. Because the model building process and analytical aspects of this technique have been
discussed in detail elsewhere (Bireley 1985, 1987; NlJSCo 1985), only a brief review of the methodology
follows.

ARIMA models for each species were fitted only to time-series data from those stations and life
history stages where occurrence was high enough to provide reasonable descriptions of natural fluctuations.
The data (densities from ichthyoplankton, catches from impingement and seines) were log transformed to
reduce skewness and to stabilize variances (Glass et al. 1975), and then averaged over the sampling period
specific to each program to ensure that data would be spaced at equal intervals in the final time-series.
The sampling periods were a week for impingement and ichthyoplankton data and a month for seine data.

The deterministic portion of the ARIMA models included explanatory variables much like nonlinear
regression models. These variables were cooling-water flow (F), species 'season indicator (S), and periodic
components which entered the model as sine or cosine functions of 1 to 6, or 12, 24, 36 ... up to 120
months; or combinations of these periods. The stochastic portion of the model described the structure of
the model prediction errors using two types of stochastic terms, autoregressive (A) and moving-average
(M). Therefore, the general form of the ARIMA models was:

Zj = Qj[l + sin(tKp) -I- cos(tKp + ....] + [Stochastic terms: A, + M, 4- ....]

where Z( were the time-series of means of the log transformed data; the subscript (t) was time in days;
the multiplier Q of the deterministic portion of the model could be either the flow (F) for impingement
models or the season indicator (S) which had a value of zero when a species was known to be absent
from the MNPS area and a value of one otherwise (Table 7); and (I) was a constant estimated from the
data either as zero or as unity. The periodic component Kp was a constant that converted the time (t)
into angular units (radians) of some specified period (p) in months. Some models had more than one
pair of sine-cosine terms to accomodate more than one periodic component.

18

A stepwise regression procedure that maximized R values was used to select the best combination
of the above variables for the deterministic portion of each ARIMA model. Next, appropriate stochastic
terms were added to the deterministic model whenever the residuals were found autocorrelated. The
methods of Brocklebank and Dickey (1986) were used to identify the stochastic structure of the residuals
from the deterministic function.

Interpretation of time-series model statistics. Because the time-series models presented in this report
characterized the abundance levels and natural fluctuations of local fish populations during the two-unit
operation period (1976-1985), the model forecasts consitute the two-unit standard- or reference-series
against which future three-unit operational monitoring data will be compared. Several summary statistics
reported with the results of the time-series models will be used for impact assessment purposes in the
future. ITie "errors" or deviations of each data point from the model forecast were separated into "above "
(positive deviations) and "below" (negative deviations) and added up by years. These sums of deviations
indicated whether the year being examined was above or below the two-unit reference series. When the
deviations are squared, the annual sums become the annual components of the model sum of squares
error (SSE). The mean squared errors (MSB's) were obtained by dividing the SSE's by the number of
degrees of freedom associated with each year and model. These MSB" values provide a basis for impact
assessment because any annual MSB can be statistically compared to the reference series model MSB by
means of a simple F-test obtained as the ratio of the two MSB's. It is expected that the annual fluctuations
of MSB during the three-unit operation period, will be within the range of MSB values reported for this
preoperational period. Note that the periods modeled at BN and NB are not the same (1976-1985 versus
1979-1985). This may cause the summary statistics to show different patterns of deviations from the
models that characterize temporal fluctuations at the two stations (Appendices XIV through XXVHI).

Table 7. The "species and program combinations for which the mulliplier variable for season (S) in their lime-sencs models wns
set equal to one.

Species Program Season

AmmodytP.^ amerkanus Larval November - July

Anchoa spp. ■ Larval May - November

Egg April - August

Menidia spp. Seine May - December

Mynxocephaliis arnaeus Larval January - June

Taulogolahrus adspprms Larval May - October

Hgg April - August

Tautnga onitis Larval May - October

Egg April - August

19

RESULTS AND DISCUSSION

The fish studies at MNPS include data on over 100 taxa from icthyoplankton, impingement, trawl,
and seine samples collected from January 1976 through December 1985 (Appendices V through XVII).
The most common of these were: Ammodytes americanus (American sand lance), Anchoa spp. (anchovies),
Gasterosteus spp. (sticklebacks), Menidia spp. (silversides), Microgadus tomcod (Atlantic tomcod),
Myoxocephalus aenaeus (grubby). Raja spp. (skates), Stenotomus chrysops (scup), Scophthalmm aquosus
(windowpane), Tautoga onitis (tautog) and Tautogolahnis adspersus (cuimer). These taxa were typical of
fish assemblages found in other areas of LIS (Baird 1873; Bean 1903; Greeley 1938; Warfel and Merriman
1944; Merriman and Warfel, 1948; Wheatland 1956; Richards 1959, 1963; Richards et al. 1963; Pearcy and
Richards 1962; Perlmutter 1971; McHugh 1972; Saila and Pratt 1973) and the northeast (Bigelow and
Schroeder 1953; Briggs 1975; Fritzsche 1978; Leim and Scott 1966; McHugh 1977). Around the Shoreham
Nuclear Power Station in mid LIS, Austin and Amish (1974) reported a similar composition of ichthyofauna,
but they found that Cynosdon regalis was an abundant larval taxon. NAI (1979) and CT DEP (P. Howell,
pers. comm) also reported that these taxa were abundant among LIS ichthyofauna.

Eight of the above taxa were selected for a detailed analysis based on their susceptibility to impact
from impingement and entrainment. The selected taxa were those that contributed at least 3% to the
total catches from either impingement or entrainment (Table 8 and Appendix V). Although winter
flounder met this criterion, this species was not included in the above mentioned group of eight taxa
because it is discussed in a separate report section (Winter Flounder Studies). American sand lance ranked
first among impinged taxa and third among entrained larval taxa. Larval anchovies ranked first in

Table 8. Percentage contributed by each taxon to the estimates of total entrainment and impingement at IV1NPS during 1976-1985.

Taxa

Entrainment
Larvae Eggs

Impingement

Anchoa spp.

Pseudopleuronectes americanus
Ammodytes americanus
Myoxocephalus aenaeus
Tautogolabrus adspersus
Tautoga onitis
Menidia spp.
Microgadus tomcod
Gasterosteus aaileatus
Gasterosteus wheatlandi

61.3

10.8

8.1

10.8

<0.1

8.5

9.7

<0.1

47.8

3.7

<0.1

5.9

1.8

55.5

1.9

1.8

27.2

0.8

0.1

0.1

5.5

0.1

0.0

3.4

<0.I

0.0

5.1

<0.I

0.0

1.7

20

entrainment. F.ggs of cunner and tautog were the two most abundant egg taxa entrained; cunner was also
often caught in other sampling programs. Silversides ranked fifth in impingement. The grubby ranked
fourth among both impinged and entrained larval taxa. Sticklebacks and Atlantic tomcod each contributed
over 3% to the total impingement.

Results for the two-unit operational period (1976-1985) are summarized separately for the
ichthyoplankton, impingement, trawl, and seine sampling programs, and are followed by a discussion for
each of the eight selected taxa. Although the analytical techniques previously described were applied to
the data of all eight taxa, not all of the analytical results provided useful interpretations for impact
assessments. Therefore, the results and conclusions that follow may be based on different techniques
depending on the sampling program and taxon.

Ichthyoplankton

Because natural ichthyoplankton mortality rates are one of the most important controlling factors of
adult fish stock abundance (Gushing and Harris 1973; Bannister et al. 1974; Gushing 1974; May 1974;
DcAngelis et al. 1977), additional mortality due to entrainment could affect local fish populations. Thus,
the plankton studies conducted at Millstone since 1973 have included ichthyoplankton entrainment esti-
mates, density indices, and species composition. The data summarized in this section arc from the period
1976 through 1985 and restricted to stations EN and NB.

Annual entrainment estimates (based on medians) for the most common larval and egg taxa are
presented in Table 9. Anchovies were the most abundant fish larva entrained; annual estimates ranged
from a minimum of 1.5x10*' in 1984 to a maximum of 1,284x10^ in 1981, and the 10-yr total was 4,056x10^
larvae. The numbers of larval sand lance and grubby entrained during 1976-1985, totaled 359 and 313x10*'
respectively and were an order of magnitude lower than the estimates for anchovies. During the past 7
yr, more cunner eggs were entrained than any other taxon (13,480x10 ). Median densities were relatively
constant and entrainment estimates ranged from 1,610 (1981) to 2,589 (1983) xlO^ eggs (Table 9). The
total entrainment estimates of tautog and anchovy eggs were about one-half and one-fifth, respectively, of
that for cunner.

21

Table 9. Annual median density (no. /500m') at EN and estimated entrainmcnt oF selected taxa.

A mm

odytes americanus larvae

Year

Median

lower

Upper

N

um. days

Pntrainment

Lower

Upper

density

95% CI

95% CI

.sampled

estimate

95% cT

95% Cl'

1976

16.2

12.8

20.4

103

18.6

14.7

23,5

1977

48.9

41.5

56.9

140

66.7

56.6

77.5

1978

58.2

38.0

77.8

116

36.4

21.9

48.6

1979

50.7

42.6

61.4

143

62.4

52.4

75.6

1980

46.6

40.3

58.7

137

66.6

57.6

83.8

1981

73.7

64.1

86.5

130

57.4

50.0

67,4

1982

11.4

9.6

14.4

113

12.4

10.4

15,6

1983

15.5

n.o

21.4

12!

19.6

14.0

27.1

1984

10.1

8.1

12.2

132

13.1

10.4

15.7

1985

5.3

5.0

7.9

124

5.8

8.8

8.6

Total

359.0

Anchoa

spp. larvae

Year

Median

Lower

Upper

N

um. days

F.nlrainment

lower

Upper

density

95% CI

95% CI

sampled

estimate

95% Cl'

95% Cl'

1976

680 0

510.2

880.0

65

448.4

334.2

576.4

1977

215.4

157.7

329.3

71

162.5

119.0

248. 4

1978

248.4

173.3

367.9

59

160.0

111.6

236.9

1979

1020.8

734.9

1302.0

60

600.9

432.6

766.5

1980

1044.6

900.2

1323.5

51

558.1

480.9

707.1

1981

2285.0

1888.9

2725.9

51

1284.1

1061.5

1 53 1 .9

1982

429.1

328.8

567.4

64

299.7

229.6

396.3

1983

SOI. 7

571.8

1119.6

76

485.6

346.3

678.2

1984

137.6

89.3

240.2

61

1.5

0.9

2.7

1985

581.0

479.7

958.3

73

454.9

375.6

750.3

Total

4055.7

Anchoa

spp. eggs

Year

Median

1 ,ower

Upper

N

um. days

P.nlrainmenl

Lower

Upper

density

95% CI

95% CI

sampled

estimate"

95% C\'

95% Cl'

1979

850.6

670.8

989.6

55

464.1

366,0

540.0

1980

449.3

1 1 5.9

614.6

38

183.1

47.2

250.4

1981

666.1

514.4

833.5

50

369.3

285.2

462.1

1982

473.5

328.3

614.1

42

213.6

148.1

277.0

1983

1563.7

1 08 1 .4

2174.5

42

503.5

348.2

700.2

1984

2401.2

1154.4

3715,8

37

807.7

388.3

1249.9

1985

22,6

0.0

75.8

74

16.0

53,7

Total

2557.3

xlO of Hsh larvae or i

22

Table 9. (continued).

Myoxocephalus aenaeus larvae

Year

Median

Lower

Upper

Num. days

Rntrainment

Lower

Upper

density

95% CI

95% CI

sampled

estimate

95% Cl'

95% Cl'

1976

17.9

15.0

22.5

73

12.0

10.1

15.2

1977

44.9

37.1

50.2

67

30.2

24.9

33.7

1978

18.4

15.2

22.3

90

8.9

7.3

10.8

1979

30.7

27.7

34.3

84

19.8

17.9

22.2

1980

30.8

26.3

37.9

90

30.2

25.8

37.1

1981

98.5

73.1

113.0

73

45.0

33.4

51.7

1982

59.2

53.3

73.0

78

46.4

41.8

57.2

1983

62.1

51,6

78.8

79

50.0

41.6

63.5

1984

45.2

36.6

53.9

82

35.8

29.0

42.7

1985

64.4

51.0

75.0

72

36.5

28.9

42.5

Total

312.9

Tautoga onilis eggs

Year

Median

Lower

Upper

Num. days

P.ntrainment

Lower

Upper

density

95% CI

95% CI

sampled

estimate'

95% Cl'

95% Cl'

1979

919.9

724.3

1153.4

80

645.8

508.5

809.7

1980

1608.4

1356.2

1277.7

72

992.1

836.5

1158.2

1981

1618.9

1404.1

1934.5

86

1385.3

1201.5

1655.4

1982

1562.9

1278.9

1709.7

84

1443.4

1181.1

1579.0

1983

1309.0

986.4

1750.2

92

953.7

718.7

1275.2

1984

1486.4

1123.4

1892.8

88

12ri.9

915.9

1543.2

1985

1519.9

1133.1

2844.8

92

1260.1

939.4

2358.6

Total

7892.3

Taulogolabrus adspersus eggs

Year

Median

Lower

Upper

Num. days

Rntrainment

1 .ower

Upper

density

95% CI

95% CI

sampled

estimate'

95% Cl'

95% Cl'

1979

3412.0

2733.3

4002.0

60

1674.7

1 34 1 .6

1964.3

1980

4365.5

3554.9

5310.5

59

203 1 .8

16-54.5

2971.6

1981

2958.3

2452.8

3941.0

58

1610.5

1335.3

2145.5

1982

3447.3

2778.0

4760.2

55

2103.0

1693.5

2903.9

1983

5934.3

4041.2

7076.8

54

2589.3

1763.3

3087.9

1984

3482.4

2892.0

4799.6

65

2153.6

1563.9

2595.4

1985

3636.3

2524.0

5893.4

64

1897.2

1316.9

3074.8

Total

13479.8

xlO of Tish larvae or eggs.

23

To investigate possible trends in icthyoplankton abundance during the period of two-unit operation,
annual mean densities (no./500 m ) were calculated for over 50 taxa of fish larvae at EN and NB
(Appendices VI and VII) and 29 taxa of fish eggs at EN (Appendix VIII). For the selected taxa these
densities are also presented in Tables 10-12. Because the standard errors of the mean densities were 20 to
200 times larger than the corresponding means, these data could not be used to describe trends. The
variablity associated with these taxa as a group, appeared related to the very high variability in the
abundance of anchovies (Fig. 6). Anchovy, winter flounder, sand lance, and grubby larvae and cunner,
tautog, and anchovy eggs comprised over 80% of the overall mean density of larvae and eggs at EN for
1976-1985 (Table 8; Appendix V). Based on mean densities, anchovies were the most abundant larval
taxon (mean density = 244/500 m^ 61% of total density at EN and 330/500 m^ 62% at NB). Cunner
eggs were dominant (mean density = 16,281/500 m^, 56% of total density) and little variation was seen
in annual mean densities of eggs.

Table 10. Annual mean fish larval density (no./500m ) of selected taxa at EN during 1976-1985.

Taxa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Mean

Anchna spp.

185.2

178.2

72.0

313.3

346.7

550.5

182.3

301.7

66.3

245.2

244.1

Psajdopleiironecles amerkanus

42.0

27.6

31.0

26.8

59.5

31.4

59.2

70.6

45.9

36.2

43.0

Ammodyles americanus

10.8

55.2

110.8

50.6

65.7

52.8

12.4

13.4

8.3

4.7

38.5

Myoxocephalus aenaeus

4.7

11.7

7.1

10.7

11.2

25.5

20.8

20.5

16.0

19.9

14.8

Tautogolahnis adspernis

5.6

12.1

0.4

3.2

12.4

13.8

8.6

12.5

1.0

2.8

7.2

Tauloga onitis

7.0

8.5

0.4

2.5

9.3

16.7

11.1

9.5

0.8

4.5

7.0

Menidia spp.

0.5

0.1

0.5

0.6

0.5

0.4

0.2

2.2

0.1

0.3

0.5

Gaslerostms aculeatus

O.I

0.1

0.2

0.1

<0.I

<0.1

<0.!

<0.1

0.0

0.0

0.0

Other taxa

32.5

42.4

24.1

32.2

39.3

61.1

42.2

59.6

25.4

73.6

43.4

Total

288.4

335.9

246.5

440.0

544.6

752.2

336.8

490.0

163.8

387.2

398.5

Table 1 1. Annual mean fish larval density (no./500") of selected taxa at NB during 1979-1985.

Taxa

1980

1981

1982

1983

Anchoa spp.
Ammodyles amerkanus
Psertdoplfnironectes amerkanus
Taulogolabnis adspersus
Tautoga onitis
Myoxocephalus aenaeus
Menidia spp.
Microgadus tomcod
Gaslerosleus aculeatus
Other taxa

Total

320.7

418.2

494.1

292.5

485.3

62.9

239.3

330.4

56.2

52.4

174.9

9.4

40.9

27.9

11.4

53.3

19.0

42.9

26.8

43.1

68.4

41.8

44.2

40.9

19.6

24.9

17.6-

34.4

42.4

7.9

8.0

22.1

10.6

17.3

18.4

27.8

28.3

6.7

11.3

17.2

6.1

9.1

13.0

11.2

11.8

9.6

11.9

10.4

0.4

0.2

0.6

0.0

0.6

<0.1

<0.1

0.1

<0.1

0.1

0.2

0.1

0.1

<0.1

0.1

<0.1

<0.1

0.0

<0.1

0.0

0.0

0.0

0.0

<0.1

36.5

36.0

58.4

94.6

71.6

45.1

49.0

56.0

24

Table 12.

Annual mean Tish egg density (no./500m

of selected taxa at EN during April through September of 1979-1985.

Taxa

1979

1980 1981 1982 1983 1984 1985 Mean

Tautngolahnts adxpemis
Tautoga onitis
Anchoa spp.
Menidia spp.

Pseudopleiironectes amerlcanus
Myoxoccphalus aenaeus
Ammodytes americanus
Other taxa

2454.5 2898.5 1908.9 1761.6 2001.2 2240.7 3016.3

714.6

1311.4

1273.9

1033.5

999.2

1122.0

1507.5

413.0

306.1

339.4

218.4

636.7

1196.9

53.2

0.0

3.4

1.5

0.3

0.7

19.8

<0.1

0.8

0.9

4.7

I.l

0.3

0.0

0.0

3.2

<0.1

<0.1

0.9

<0.1

0.0

0.5

0.3

0.0

0.0

0.0

0.0

0.0

0.0

377.2

138.8

277.5

253.3

220.6

235.5

374.7

2326.0

1137.4

452.0

3.7

1.1

0.6

<0.1

268.0

Total

3963.6 4659.1 3803.9 3269.1 3858.7 4814.9 4952.2

4188.8

800
700

2 600

a

>; 500-

^ 400

5 300-

^ 200-

s

100
0

77 78 79

83 84 35

900-

NB

300-

y\

^ 700-

/\

A

Q 600-
>2

y^

\/

\

i 500-
^ 400-
<300-

^^•^ \

\y

/ \ \

All species
Anchovies

S 200-
100-

^^^

\y--

Other species

Figure 6. Annual mean density (no./500 m ) for all larval species combined, anchovies and all other species at EN
and NB.

25

Impingement

Impingement estimates were calculated from January 1975 to .December 1985 using daily cooling
water volumes (for 24 h starting at 0800 h). Over 100 taxa of fish and invertebrates have been impinged
over the past 10 years (Appendix IX). Impingement estimates for the selected taxa are presented in Table
1.1. Sand lance accounted for almost 50% of the total number impinged. Prior to 1984, sand lance
accounted for less than 1% of the total impingement (NUSCo 1986a). However, in 1984, an estimated
390,000 sand lance were impinged at Unit 2 during the week of July 18th. This estimate was based on a
single 24-h sample, and qualitative observations made during the remEiinder of the week indicated that the
numbers of impinged sand lance decreased rapidly thereafter. The sand lance is a schooling species (I^im
and Scott 1966) and a large school probably encountered the intake structures. A similar short-term large
impingement of a schooling species, Atlantic menhaden (Brevoorlia tyrannus) occurred in 1971 (NUSCo
1982b). At that time, approximately one million juvenile menhaden were impinged in August at Unit 1
(the only unit operating then). Excluding sand lance, seven fish taxa dominated the impingement collections
and accounted for over 90% of the fish impinged. These included winter flounder, silversides, grubby,
anchovies, Atlantic tomcod, cunner, and sticklebacks. Except for the cunner and anchovies, these species
were impinged in the winter months (December through March). The winter flounder was the most
abundant and accounted for approximately 20% of the annual impingement catch.

There was no apparent trend for the total number of fish impinged annually during the two-unit
operational period (Table 13). Although impingement samples wrre collected only at Unit 1 after 1983,

Table IV Annual impingement estimates Tor selected taxa impinged, calculated using (lows frnm 0800-0745 (Units 1 A 2 combined
by year except during 1984-85 when Unit 2 was estimated alone).

[axa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Total

Ammodylrs amiriranus

65

69

277

98

192

269

iTT

449

48-5411

73

487039

rsinidoplnironpclps ampricamis

5654

7622

7676

23544

7207

7640

8875

13467

2542

2765

86992

Anchoa spp.

5606

804

869

3340

4426

4755

5895

52280

4200

342

82517

Myoxorpphalus apnanu

2108

2357

7528

3699

10736

5450

6486

14634

2359

4553

59866

Menidia spp.

1585

1328

12155

12187

10199

3733

3872

8136

1042

1480

55717

Mirrogadiis tomcnd

91

339

2398

1455

1314

8121

11868

2860

4938

1129

34513

Gasleroslrw: spp.

2411

5375

5511

9918

7441

30656

Gasternstnis anileatus

6817

2951

9472

1055

852

21147

Tautngnlahnts adsperms

903

1429

1862

3110

1157

2566

3851

2900

1188

466

19432

Gasip.rosteus whralhndi

601

1393

14381

702

21

17098

Tautoga nnitis

883

809

1074

866

338

814

1579

1512

664

122

8661

Other taxa

6222

7777

7187

9318

9502

11207

14530

38377

7286

4463

1 1 5893

Tolal

25528

27909

46517

67535

52512

51973

61436

1 58468

51 n87

16266

1019531

26

the highest estimated impingement occurred in 1984 due to the large number of sand lance impinged that
year. Without this large impingement, the estimate (25,976) for that year would have been among the
lowest since 1976. The smallest estimated impingement occurred in 1985 after sampling at Unit 1 was
eliminated.

Trawls

Over 90 taxa of fish were taken by trawl at six stations in the vicinity of MNPS during the 10 yr of
two-unit operation (Appendices X and XI); Oviat and Nixon (1973) and JefFeries and Johnson (1974)
found that demersal fish communities in Narragansett Bay were composed of many ot the same taxa. Six
fishes comprised over 80% of the trawl catch. The winter flounder was the most abundant and accounted
for approximately 45% of the total catch; about one-third of the winter flounder was caught at NR. The
second most abundant species was scup. Most scup were juveniles and they accounted for almost 15%
of the catch. Over 40% of them were caught at NB. Biologists from CT DEP have determined that the
Niantic Bay region is the primary nursery area for scup in LIS (P. Howell, pers. comm.). The windowpane
accounted for over 7% of the trawl catch and over half of them were caught at BR. Anchovies, skates,
and silversides had similar catches and together accounted for an additional 15% of the total. Over 90%
of the anchovies were taken in Niantic Bay at IN and NB. Skates (66%) were mostly caught at the two
deep-water stations (TT and BR), while silversides were often found at the nearshore stations (IN, 37%;
NR, 27%; and .IC, 25%).

The total annual catches of the selected taxa are presented in Tables 14 and 15. Their catch remained
relatively stable, except for anchovies and cunner. The former exhibited large year to year fluctuations in
catch, probably because of their highly variable distribution, and the latter showed a decline since 1976.
This apparent decline of cunner is discussed later.

27

Table 14. Trawl catch of selected taxa by year (1976-1985).

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Total

Number of samples

908

936

936

936

972

935

936

936

936

936

9367

Taxa

PseudoplR^irnnnrlcs amerkanus

7875

5752

6055

10694

1237S

13124

13517

16799

14027

8869

109090

Anrhoa spp.

980

580

2223

15

113

577

39

88

178

9997

14790

Menidia spp.

2151

1224

1060

2059

1003

356

427

635

348

465

9728

Taulngolahrus adspprsns

1009

1032

359

1381

981

825

561

412

246

143

6949

Mynxornphalus aenaetis

191

276

591

316

458

866

788

904

595

498

.5483

Tautnga oniti:\

251

292

246

283

138

235

228

159

110

136

2078

Mirrogadus tomcod

19

25

40

49

125

279

1147

132

90

85

1991

Gasternsteus anilnatKS

19

22

13

103

38

192

116

256

940

199

1898

Ammodylns americanus

1

4

60

127

37

117

14

19

10

19

408

Other laxa

6678

7560

5855

7760

9398

15350

I53I0

15013

13271

10733

106928

Total

19174

16767

16502

22787

24669

31921

32147

34417

29815

3 1 1 44

259343

Table 15. Trawl catch of selected taxa by station (1976-1985).

Station

JC

NR

Nn

TT

nR

IN

Total

Number of

samples

1563

1559

1563

1563

1563

1556

9367

Taxa

Psmidnpleuroni'cti'^ americanus

10786

33899

15760

18697

12923

17025

109090

Anchoa spp.

718

240

10263

293

15

3261

14790

Menidia spp.

2186

2380

1312

493

152

3205

9728

Tau [ogolahru.\ adspprsus

1412

297

495

260

377

4108

6949

Mynxncnphalus arnafus

846

2075

329

426

647

1160

5483

Tautoga onllis

442

427

252

177

222

558

2078

Microgadux tomcod

638

466

484

71

27

305

1991

Gasteromeiis aculcalua

1254

612

S

10

6

8

1898

Ammodytps ampricawis

19

94

4

28

257

6

408

Other taxa

10943

6464

26911

17632

25901

19116

106928

Seines

Approximately 30 different taxa have been caught by seine during the 10 yr of two-unit operation
(Appendices XII and XIII). Ilillman et al. (1977), found many of the same taxa in the MNPS area. Two
taxa accounted for over 90% of the total seine catch from 1976 through 1985. Silversides dominated the
shore-zone seine catches and accounted for about 75% of the total; Fundulus spp. (mummichogs and
striped killifish) accounted for an additional 12%. About 80% of the total seine catch (Table 16) was

28

Table 16. Seine catch of selected taxa by station (1976-1985).

JC

WP

GN

Total

Number of samples

300

314

321

93 5

Taxa

Menidia spp.

72783

9879

7817

90479

AmmodvlPS americanus

2

197

855

10.54

Gasternstnn: aculmnis

227

19

23

269

Psmdopleuronectes americanus

19

7

59

85

Gasterostms wheatlandi

12

13

14

39

Myoxocephalus aenams

4

7

7

18

Anchoa spp.

11

1

0

12

Tautogolabrus adapp.rxus

5

1

0

6

Tautoga onitis

4

0

0

4

Other taxa

12953

2517

1401

16871

Total

86020

12641

10176

108837

Table 17. Seine catch of selected

taxa by year (

1976-1985).

1976

1977

1978

1979

1980

1981

1982 1983

1984

1985

Total

Number of samples

66

72

72

72

72

72

80

99

174

156

935

Taxa

Menidia spp.

40620

18179

1178

1233

7764

3418

5408 9007

2330

1342

90479

Ammodytes americanus

6

520

16

51

10

318

82

30

21

0

1054

Casterosteus acuteatus

8

151

8

30

2

3

5

49

9

4

269

Pseudopleuronectes americanus

4

6

4

1

2

9"

2

1

18

38

85

GasternstKUs wheatlandi

8

3

5

5

1?

39

Myoxocephalus aenaeus

3

2

1

2

0

0

3

1

3

3

18

Anchoa spp.

0

0

0

0

2

0

7

2

1

0

12

Tautogolabrus adspersus

0

0

2

0

0

0

3

n

1

0

6

Tautoga onitis

0

0

0

0

0

0

4

0

0

0

4

Other taxa

2302

2466

1200

1116

1051

1114

1254 3112

2117

1139

16871

Total

42943

21324

2409

2433

8831

4870

6771 12207

4505

2544

108837

taken at .IC. Hundreds of juvenile silversides were routinely caught at this site during the summer months
because this station is in a nursery area for shore-zone fish.

Total annual seine catches of all taxa combined (Table 17) showed no apparent trend during the
period, although totals. were highest in 1976 and- 1977. Because silversides dominated all the annual
catches, total catches were largely a function of silversides catches. Over half of all the silversides were
caught in 1976 and 1977, thus catches for all taxa combined were also highest in 1976 and 1977. Except
for silversides, there has been no apparent trend in the total annual seine catches of the selected taxa since
1976. Results of the silversides data analysis are discussed later.

29

Selected species

Ammodytes americanus, American sand lance

The American sand lance {Ammodytes americanus) is found from the Arctic to Cape Hatteras
(Bigelow and Schroder 1953). They are primarily pelagic plankton feeders (Richards 1982). Individuals
form large schools and are found over sandy bottoms from near shore to the edge of the continental shelf
(Richards 1963; Leim and Scott 1966). Sand lance mature in one to two years and spawn between
December and March (Westin et al. 1979). Covill (1959) and Meyer et al. (1979) reported that large
annual fluctuations of sand lance abundance occur along the Atlantic coast.

Sand lance have been collected in all fish programs. Except for 1984, when a large school of sand
lance was impinged, these fish have generally contributed less than 1% to annual total impingements
(NUSCo 1984a). The sand lance is a winter spawner and its larvae were collected from January to May
(Fig. 7); its abundance ranked third at EN and second at ND (Tables 10 and 12). Annual entrainment
estimates during the two-unit operation period (1976-1985), were based on median densities and ranged
from 5.8x10 (1985) to 66.7x10 (1977) (Table 9). Because sand lance eggs are demersal and adhesive
(Erizsche 1978), they were rarely collected. Sand lance were collected irifrequently in the trawl and seine
samples, probably because juvenile and adult sand lance burrow into the sand (Leim and Scott 1966),
thereby avoiding these gear.

Annual impingement estimates for sand lance never exceeded 450 except in 1984 when 390,000 sand
lance were impinged during the week of July 18 (NUSCo 1985). This mass impingement of sand lance
did not recur and the estimated number of sand lance impinged in 1985 was comparable to historic levels
(Table 13). Time-series analysis did not adequately describe the fluctuations of impinged sand lance
because of the large numbers in 1984 and the low levels of impingement during all the other years.

Larval sand lance were abundant in plankton collections from 1977-1981, but a marked decrease in
densities occurred after 1981 (Fig. 7). The temporal catch distribution of larval sand lance was as variable
as that seen in impingement (Tables 10 and 12). Larval sand lance were caught in large numbers during
short time periods. For example, more than 60% of the annual 1978 cumulative density was caught at
EN between January 23 and February 3, and more than 35% of the 1980 cumulative density on May 19.

30

LARVAE AT EN

YEAR (19 )

LARVAE

AT

NB

BOOO-

YEAR (19 — )

7000 -

„.

„

o
o

6000 -
5000 -

d

4OO0 -

fe

3000 -

2000 -

■z

J^

BO

1 000 -
0 -

^'>^

^ —

- 8-3

=^^-

R-s

"^

S2

OIJAN OITEB OlMAR OlAPR OlMAY OIJUN OIJUL OlAUG O l SEP OlOCT Ol

MONTH

O IDEC O 1 ,

Figure 7. Annual cumulative density (no./500 m ) of sand lance larvae at EN and NB.

At NB, more than 70% of the 1981 cumulative density was collected on April 15. These patterns could
be explained by the finding that larvae that hatch together tend to remain together (Norcross et al. 1961).

Time-series models of larval density at EN and NB fitted observed data well and had R values of
0.74 and 0.92, respectively (Fig. 8; Appendix XIV). These models included periodic components of 4 and
6 mo, suggesting that the abundance of sand lance larvae is inherently seasonal within each year. The
previously mentioned decline in abundance of sand lance after 1981 has become a feature of the time-series
model, which provides an average characterization of the years of high (1977-1981) and low (1982-1985)
abundance. Therefore, the measures of variation from the model forecasts (MSE) at EN and NB (Appendix
XIV) are presented as a two-unit operational baseline for future assessments.

31

a.o

7.0
6.0
5.0
4.0-
3.0
2.0
1.0
0.0
-1.0
-2.0

7.0

^ 6.0 i

X 5.0
ro

2 4.0

o
o

.!5_ 3.0

cH 2.0

NB

Figure 8. Time Fcries plots of sand lance larvae at EN and NB; Torecast ( — ), 95"o confidence limils (--), and mean
weekly log-transformed density (no./500 m ) (*).

Anchoa spp., anchovies

Two anchovy species, the bay anchovy {Anchoa mitchi/lf) and the striped anchovy {Anchoa hepsclus)
have been collected in the MNPS area. Eggs of the two species can be easily distinguished and, based on
their relative proportions, the bay anchovy was by far the most common at MNPS (more than 80%).

The bay anchovy is perhaps the most abundant fish along the Atlantic C^oast (McHugh 1977). They
are commonly found inshore during the warmer months and move offshore in the winter. Hildebrand
(1943) believed that each section of the coast had a distinctive population and all migrations were inshore

32

and offshore movements. In LIS, spawning takes place in depths of less than 20 m during June through
September (Richards 1959). Eggs are pelagic and hatch in 24 h at approximately 27°C (Kuntz 1914).
Development is rapid and individuals may mature within 2.5 mo of hatching, at a size of 34 to 40 mm;
its life span is probably not more than 2 or 3 yr (Stevenson 1958).

Anchovies were among the four most abundant taxa collected in all programs except seines. Larval
abundance ranked first at both EN and NB and egg abundance ranked third at EN (eggs from NB were
not identified) (Appendices VI, VII and VIII). During the two-unit operational period, annual larval
entrainmcnt estimates, based on median densities ranged from 1.5x10 in 1984 to 1,284.1x10 in 1981.
Although median larval densities at EN were generally low (1976-1978), high (1979-1981), and low again
(1982-1985), the actual number of anchovies entrained during the same periods did not follow that pattern
because entrainment is a function of plant operating conditions. However, the highest and the lowest
estimates at EN also occurred in 1981 and 1984, respectively. In addition, both the entrainment estimate
and median density of larval anchovies at EN in 1981 were significantly higher (p < 0.05) than in any
other year (Table 9). Also the number of larval anchovies entrained in 1984 was significantly lower than
in any other year. Annual egg estimates ranged from 16.0x10 in 1985 to 807.7x10 in 1984 (Table 9).
Although annual impingement estimates varied more than two orders of magnitude (342 to 52,280), it was
the third most abundant taxon impinged (Appendix IX). Among the species taken in trawls, anchovies
ranked fourth (Appendices X and XI).

Near MNPS, anchovies migrated inshore in May and June and were available to the various NUEL
sampling gear through October (Fig. 9). Adults (median length of 77 mm) were impinged primarily from
May through June, which corresponded to the time of their spawning. Eggs were abundant from June
through July and larvae .July through August at EN and NB. Juvenile anchovies (median length of 27
mm) were caught in trawls during August through October, primarily at NB and IN.

Because anchovies mature in one year, changes in larval density in any given year should result in
corresponding changes in adult and egg abundances the next year. However, this pattern was clearly not
observed in the annual catches of anchovies during the last three years (1983-1985) of the two-unit
operational period. In 1983 and 1984, the densities of eggs at EN and the number of adults impinged
were equal to or higher than in previous years, but the 1984 larval densities at both EN and NB were
lower than in any previous year (Tables 10, 1 1, and 13; Fig. 10). This minimum was probably related to

33

80
60 :
40 ■

PROGRUi
l-UPINCeUENT

L-LARVAE
T-TRAVW.

20

lELT lELT lELT lELT lELT lELT PROGRAU
I — 5 —i 1 — 6—1 I — 7 —i 1—8 — I I— SH 1-10H UONTH

Figure 9. The monthly percent distribution of anchovies collected in impingement plankton and trawl samples.

the high abundance of a planktivorous ctenophore that occurred during the summer of 1984 (see tautog
subsection for a further discussion of this phenomenon). As expected, the catch of adults in impingement
samples and the density of eggs decreased the following year. However, later in 1985, a large increase
occurred in larval density (compared to 1984), which was followed by the largest annual catch of young-
of-the-year in trawls (Fig. 11). Because the 9. 1-m trawl does not sample anchovies well, due to their small
size and patchy distribution, year to year comparisons based on these data are generally not useful.
Nevertheless, the 1985 increase was probably real because the mean annual trawl catch for that year was
nearly an order of magnitude larger than in any other year, and was significantly larger than the mean in
any of the previous three years. These fluctuations did not appear to be related to MNPS operations nor
to the abundance of adults and eggs, but rather caused by density-dependent mechanisms as other re-
searchers have reported (Lasker 1974).

The seasonality of anchovy catches in plankton and impingement programs was described by the
periodic components in the time-series models (Appendices XV, XVI, and XVII). The models of egg and
larval abundance explained the data better (R values larger than 0.84) than the impingement model did
(R =0.69). The 1984 decline in larval abundance is now a feature of the two-unit operational series
described by the model (Appendix XVII). The lower R value of the impingement model was probably
the result of the unusually high 1983 catches (NlJSCo 1984a). Summaries of these baseline models are
presented in Appendices XV, XVI, and XVII.

34

STAT I ON—ECCS AT EN

YEAR (19 )

O 20000

t 1 0000

OIJAN 01FEB OTMAR OTAPR OlMAY OIJUN OIJUL OlAUC O 1 SEP 010CT 0 1 NOV 01DEC OIJAN

MONTH

STAT JON— LARVAE AT EN

YEAR (19-

O 20000

g IOC

OIJAN OlFEB OlMAR 01APR OlMAY 01

JN OIJUL OlALTC 0 1 SEP OlOCT 0 1 NOV 01DEC OIJAN
MONTH

STATION-LARVAE AT NB

O 20000

t 10000

YEAR (19 — )
81

OIJAN OlFEB 01MAR OlAPR O 1 MAY OIJUN OIJUL OlAUC 0 1 SEP OlOCT 0 1 NOV OlDEC OIJAN

MONTH

Figure 10. Annual cumulative density (no./500 m') of anchovy eggs at EN and larvae at EN and NB.

35

h-

40

Qn

L±J

D_

30

X

C)

\—

<

V()

u

z

<

10

:2

—1

<

0

<

10

— ; 1 1 1 1 1 1 1 1 1

76 77 78 79 80 81 82 83 84 85

YEAR

Figure 11. Annual mean catch of anchovies taken by trawl; the vertical bars are approximated QS'ii confidence
intervals for each year.

Gasterosteus spp., sticklebacks

The threespine stickleback {Gasterosteus aculeatus) and the blackspotted stickleback {Gasterosteus
wheatlandi) are small, nearshore fishes. The threespine stickleback is distributed throughout the north
polar regions and as far south as Chesapeake Bay in the Western North Atlantic. The blackspotted
stickleback is found only in the Western North Atlantic from Newfoundland to I, IS (Perlmutter 1963).
During the spring, both species move into salt marshes and tidal rivers to spawn (Worgan and Fitzgerald
1981). However the two species are found in different salinity regimes during their reproductive season,
and thus do not compete for resources during spawning (Audet ct al. 1985). The threespine stickleback
is the larger fish of the two species.

Threespine and blackspotted sticklebacks are very similar in appearance and are not easily distinguished
(Bigelow and Schroeder 1953). Because of this similarity, the blackspotted stickleback was not identified
in MNPS collections until October 1981 (NUSCo 1982a). Although Fitzgerald and Whoriskey (1985)
found no size overlap between these two species, the length frequency distributions of individuals collected

36

at MNPS overlapped at 30 to 35 mm (Fig. 12). Thus, length frequencies could not be used to separate
the species in earlier data. Data for the two species were combined.

1 ooo zoo o

FREQUENCY

500 1 OOO

FREQUENCY

Figure 1 2. Length frequency distribution of sticklebacks.

niackspotted and threespine sticklebacks were collected in all programs, but were only abundant in
impingement samples from fall through spring. Adults and young-of-the-year remain in the spawning areas
until late summer (Fitzgerald 1983), which may account for the low abundance of these fish during the
summer. Approximately 35% of all sticklebacks impinged at MNPS were taken in 1983 (Table 13). The
estimated impingment of sticklebacks in 1984 and 1985 was much lower, because sampling had been
eliminated at Unit 1. '['he estimated number of sticklebacks impinged ranged from 2,411 to 9,918 in the
period of two-unit operation prior to 1984, but no trend was apparent and, presumably, no impact had
resulted from MNPS operations.

Sticklebacks were sufficiently abundant for time-series modeling in only impingement samples. The
R for the impingement time-series model was 0.82, demonstrating a good fit to the data. Cooling- water
flow, an annual periodic component, and a short term 4-mo cycle described impinged stickleback abundance.
A summary of this baseline model is presented in Appendix XVIII.

37

Menidia spp., silversides

Two species of silversides dominate the shore zone along the Connecticut coast, the Atlantic silverside
{Menidia menidia) and the inland silverside {Menidia berylUna). Both species are sympatric along the
Atlantic coast, with the Atlantic silverside ranging from the Gulf of St. Lawrence to the Chesapeake Bay
and the inland silverside ranging from Cape Cod to South Carolina (Johnson 1975). Both species spawn
as yearlings and have a life cycle that ranges from one to two years. Both are omnivorous, feeding on
copepods, mysid shrimp, fish eggs and young squid. They are important as forage food for larger fish
species (Bigelow and Schroeder 1953).

Silversides collected in MNPS programs were identified to genus during some portion of the two-unit
operational period. When identified to species, Menidia menidia were the most abundant (over 90%).
However, to investigate long-term trends the two species were always analyzed together as a single taxon.
Silversides, the most abundant taxon among those collected in the seine program, ranked third and fifth
among taxa sampled by the trawl and impingement programs, respectively. Silversides were not abundant
in plankton samples because their eggs are adhesive (Bigelow and Scliroeder 1953) and larvae and juveniles
stay close to shore (Bayliff 1950).

Pronounced seasonal patterns of abundance were evident in seine, trawl and impingement collections
(Fig. 13). The seine catches in the summer and early fall were composed primarily of juveniles (20-50
mm), while catches in trawl and impingement collections were composed of larger fish (60-120 mm)
collected from deeper waters in the winter. This pattern of catches seems related to the offshore migrations
of silversides in the late fall and winter reported in other studies (Bayliff 1950; Bigelow and Schroeder
1953; Conovcr 1979). The average monthly catches of silversides taken by trawls in the MNPS area during
the last in yr also showed a pattern pointing out to regular winter offshore migrations (Fig. 14), Silversides
began to move away from the shore-zone and were found at the nearshore station, JC, in September.
They were collected from NR, NB and IN in November and were found at the two offshore stations, BR
and TT, December through March.

Although the total annual seine and trawl catches of silversides (Tables 17 and 14, respectively)
suggest a common and decreasing trend, a similar pattern was not evident among annual impingement
estimates (Table 13). Further, the variances associated with those data were high as demonstrated by the

38

SEASON
Wl NTER

SUMMER

:ngth

20

40

60 B

80 fei^iXiJ-^^a

1 00 ^ggsgggg^sgsgs^g^

1 20

20

40

60

SO
1 00
1 20

20

40

60 I

SO p
100
1 20

20

40

60

80
1 00
1 20

1 000 2000 0
FREQUENCY

2000 4000
FREQUENCY

SsXS^rtb%i^i

5000 TOOOO
FREQUENCY

TRAWLED

I MP I NGED

Figure 13. Length frequency distribution of silversides by season.

wide (and overlapping) 95% confidence intervals in Figure 15. Because NUSCo (1984b) found that catches
from GN, a control station located away fi-om the influence of MNPS, were correlated with catches from
WP, a potentially impacted station, the apparent declines in both seine and trawl catches were attributed
to a regional decline unrelated to the construction and operation of MNPS.

Silversides abundance was well described by the time-series models for seine data (R > 0.80; Appendix
XIX) and impingement data (R = 0.75; Appendix XX). All models had an annual periodic component,
except the seine model for JC station which had only a 6-mo period. Summaries of these baseline models
are presented in Appendices XIX and XX.

Microgadus tomcod, Atlantic tomcod

The Atlantic tomcod {Microgadus tomcod) is the most abundant member of the cod family collected
in the monitoring programs at MNPS. It ranges along the Atlantic coast of North America from

39

100-

, /

o

y^ BR

a

*^

Q.

50-

3
E

0-

100

T

i-

TT

. /

c

>.^^

Q-

50

<

>

3
E
o

0

12 3 4 5 6 7
MONTH

9 10 11 i:

1 2 3 4 5 6 7
MONTH

9 10 11 12

100'

/

o

NB

/

J

a.

50'

/^

13

h

o

100

J

-2

IN

/

a

50

/

>

/

3

1
o

n-

.-— ^-^

1 2 3 4 5 6 7 8 9 10 11 12
MONTH

1 2 3 -4 5 6 7 8 9 10 11 12
MONTH

100-

JC /

50-

_^

+ *

1 2 3 4 5 6 7 a 9 10 11 12
MONTH

Figure 14. Silversides 10-yr trawl-catch monthly averages (no./0.69 km) expressed as a cumulative percentage of total
annual catches.

40

ID
<

1500-

(Y

1300-

UJ
Q.

1 100-

X

900-

f—

<

700-

O

z

500-

<

Ld
2

300-

_l

100-

~D

z

-100-

z

<

-300-1

o

f—

[r

LlJ
Cl

j:
o
I—
<

<

LlI

<

ZD

<

4 85

YEAR

Figure 1 5. Silversides annual mean catches taken by seine (a) and trawl (b); the vertical bars are the approximated
95% confidence intervals for each year.

41

Newfoundland to Virginia (Bigelow and Schroeder 1953). Howe (1971) reported that tomcod reach sexual
maturity at about 130 mm; they migrate up rivers to spawn in fresh or brackish water from November
through February. Eggs are adhesive and are found attached to the substrate. After spawning, adult and
larval tomcod remain in or near the estuary. They move to cooler waters during the summer months.

Tomcod were caught in all fish programs, but were more abundant in the impingement and trawl
samples than in plankton collections. Eggs are adhesive and larvae tend to remain in or near spawning
areas, which are habitats that were not sampled by NUSCo programs. Over 98% of impinged tomcod
were adults (fish larger than 130 mm) and about 90% of these were taken during fall and winter (Fig. 16).
About 58% of the total tomcod impingement estimate during the two-unit operational period, were
impinged during 1981 and 1982; estimates for other years ranged from 91 to 4,938 fish (Table 13). In
trawls, more individuals were caught nearshore (stations NR, IN, NB and JC) than offshore (BR, TT)
(Table 15). Young-of-the-year dominated the catches of tomcod taken by trawl in the spring and summer;
adults were caught mostly in the fall and winter (Fig. 16). Trawl catches were seasonal and peaked from
April through June except at NR, where most fish were caught during their spawning season (Fig. 17).
Tomcod trawl catches were higher in 1981 and 1982 than in any other year (Table 14); during these two
years impingement estimates were also highest. This 1981-1982 peak could not be related to MNPS
operation or construction activities and, thus, it was attributed to an unusually large year-class.

SEASON

LENGTH

SPR I NG-SUMMER

60

80

1 0 0

-I 20

1 40

1 60

FALL -WINTER

60
80
1 00
1 20
140
1 60

0 200 400
FREQUENCY
TRAWLED

600

0 2000 4000
FREQUENCY
MP I NGED

6000

Figure 1 6. Length frequency dislribution of tomcod.

42

100

/ '"

*

=(i=

=^

c

/ '^

e

i

a.

50

1

>

1

O

0-

*-

/

1 2 3 4 5 6 7
MONTH

9 10 11 12

1 2 3 4 5 6 7 a 9 10 11 12
MONTH

1 2 3 4 5 6 7
MONTH

9 10 11 12

9 10 11 12

100

F

"c

m /

it

j-

a.

50

/

>

, ■ , .--^

o

„r-*-^'><

9 10 11 12

5 6 7 8 9 10 11 12
MONTH

Figure 17. Atlantic tomcod 10-yr trawl-catch monthly averages (no./0.69 km) expressed as a cumulative percentage
of total annual catches.

.43

The tomcod impingement data were well described (R =0.69; Appendix XXI) by a time-series
model. This model had annual and six-month periodic components. A summary of this baseline model
is presented in Appendix XXI.

Myoxocephalus aenaeus, grubby

The grubby {Myoxocephalus aenaeus) is found in coastal waters, commonly in eelgrass habitats, along
the Atlantic coast of North America from the Gulf of St. Lawrence to New Jersey (Bigelow and Schrocder
1953). It spawns throughout the winter (Lund and Marcy 1975) and Richards (1959) reported finding
larvae in shallower areas of LIS from February to April. The grubby tolerates a wide range of temperatures
and salinities (Bigelow and Schroeder 1953).

The grubby is a resident of the waters near MNPS and both larvae and adults have been collected
in the NUSCo monitoring programs. Eggs were rarely collected because they are demersal and adhesive.
Adult fish were also rare in seine samples.

Overall mean larval density of grubby during the two-unit operational period ranked fourth at EN
and sixth at NB (Appendices VI and VII). These larvae were collected from February through May at
both stations (Fig. 18). Annual entrainment estimates ranged from 9x10 in 1978 to 50x10 in 1983 and
peak larval abundance, as measured by both median (Table 9) and mean densities (Tables 10 and 12),
occurred in 1981. However, the temporal pattern described by the annual means and medians did not
correspond to the pattern described by the cumulative mean densities shown in Figure 18. Cumulative
density at NB was highest in 1985, followed by 1981, 1983 and 1982, while at EN it was highest in 1981,
followed by 1982, 1983 and 1985. Most likely, these discrepancies were not related to any real differences
but were a result of of the high variablity inherent of the plankton data (variances were 20 to 200 limes
larger than the corresponding means).

Over 90% of the grubby in the impingement and trawl samples were adults (60 to 120 mm) (Fig.
19). Adult catches ranked fourth among impinged taxa and ninth among species taken in trawls (Appendices
IX and X). Impingement estimates ranged from 2,108 in 1976 to 14,634 in 1983, and 42% of the total
impingement during the two-unit operational period (1976-1985) occurred in 1980 and 1983. The

44

200 •^

^

/

STAT 1 ON~LARVAE

AT

EN

•EAR (19 —

1 oo ■

000 ■

/
/
/

900 J

/^^'

BOO -

r

700 -

_ri~

600 -

I^

500 -

.■■'

3

400 -

^^

^^''^

i

1 00 -

0 .

01JAN OlFEB OlMAR 01APR 01

JN OIJUL OlAUG OlSEP OlOCT O 1 NOV OlDEC O 1 J AN
MONTH

STATION-LARVAE AT

700 -

SOO

500

400

300

^N 01FEB OlMAR OlAPF

S.Y O 1 JUN OIJUL
MONTH

\UG OlSEP OlOCT OINOV OlDEC 01

Figure 18. Annual cumulative density (no./500 m ) of grubby larvae at EN and NB.

impingement estimates for 1984 and 1985 were relatively low and did not include Unit 1 impingement
because the sluiceway was operational, but those estimated for 1976 and 1977 were smaller.

The grubby was taken in trawls primarily from November through April except at JC where it was
taken throughout the year (Fig. 20). Almost 75% were caught at the nearshore stations JC, NR and IN
(Table 15). Total catch of grubby taken in trawl for the two-unit operational period was 5,483 fish (Table
14) and annual catches ranged from 191 to 866. Annual mean catches did not show any trend over the
1976-1985 period (Fig. 21) and the observed fluctuations could not be related to MNPS two-unit operations.

45

500 1000 1500 2000
FREQUENCY

2000 4000
FREQUENCY

"RAWLED

I MP 1 NGED

F^igure 19. Leiiglh frequency distribution of grubby

Time-series models described well the temporal abundance of grubby in impingement and larval
collections (Appendices XXII and XXIII). All R^ values were over 0.90 in the larval series models. These
larval models had annual and 4-mo periodic components as their main deterministic features. Cooling-water
flow and an annual cycle accounted for 83% of the variability in the impingement model. All the models
have been consistent for the past 3 yr (NUSCo 1984a, 1985, 1986a) suggesting that they included the most
relevant variables for describing the natural fluctuations of this species. Summaries of these baseline models
are presented in Appendices XXII and XXIII.

Tautoga onitis, tautog

The tautog {Tautoga onitis) is found from New Brunswick to South Carolina, but is most conmion
from Cape Cod to Delaware Bay (Cooper 1965). Adult and juvenile tautog are found around rocky areas,
ledges, mussel beds, breakwaters, an other similar nearshore habitats from eariy May until late October
(Bigelow and Schroeder 1953; Cooper 1965). .Juveniles are also found in eelgrass beds and among
macroalgae in coves and channels (Tracy 1910; Briggs and O'Conner 1971). Both juveniles and aduhs
have a home site where they remain inactive and under cover at night; during the day larger fish move to
other locations to feed, but juveniles remain close to their home sites (Olla et al. 1974). During winter,
adults move to deeper water and remain inactive while juveniles stay inshore to overwinter in a torpid
state (Cooper 1965; Olla et al. 1974). Tautog males become sexually mature at age 3 and females at age
4 (Chenoweth 1963). Spawning occurs from mid- May until mid-August in LIS (Wheatland 1956;

46

1 2 3 4 5 6 7
MONTH

9 10 11 12

100

1 1 1 1 1 1^

1

/^ ''^

a

j

Q.

50-

/

>

1
U

0

1 2 3 4-567
MONTH

9 10 11 12

100

. /

c

z*-'^ NB

t:

y

Q.

50

If

>

"5
E
o

n-

^

1 2 3 4 5 6 7 a 9 10 11 12
MONTH

1 2 3 4 5 6 7
MONTH

9 10 11 12

9 10 1112

Figure 20. Grubby 10-yr trawl-catch monthly averages (no./0-69 km) expressed as a cumulative percentage of total
annual catches.

47

o

I —

cr

LjJ
Q_

X

o

I—
<

<

LJ

<

ID

<

— I 1 1 1 1 1 1 1 1 1 —

76 77 78 79 80 81 82 83 84 85

YEAR

Figure 21. Annual mean trawl -catches of grubby; the vertical bars are the approximated 95% confidence intervals for
each year.

Chenoweth 1963). The eggs are pelagic and are concentrated in the upper 5 m of the water column
(Williams 1967). Young become benthic and move inshore after metamorphosis, which is completed by
10 mm (Fritzsche 1978).

Tautog was found in all sampling programs, but was most abundant in the June through August
plankton collections (Tables 10, 12, and 14). Catches were low in impingement, trawl and seine samples.

Tautog eggs were the second most abundant egg taxon entrained (Appendix V) during the two-unit
operational period. Annual egg entrainment estimates did not vary widely and ranged from 646x10 (1979)
to about 1,400x10 (1981 and 1982). Both median and mean egg densities (Tables 9 and 11) varied over
a relatively small range; medians from 920 (1979) to 1,619/500 m^ (1981) and means from 715 (1979) to
1,506 /'500 m (1985). The lowest egg density as indicated by both measures occurred in 1979, but the
highest egg density occurred in either 1981 or 1985, depending on the index of abundance used. Clearly,
no trend can be discerned from these data.

4S

Tautog larvae ranked fifth at NB and seventh at EN and the annual cumulative larval densities were
usually greater at NB than at EN (Fig. 22). Although tautog egg abundance was relatively stable throughout
the study period, larval abundance was not. Larval densities were considerably lower in 1978 and 1984
than in any other year (Tables 10 and 12). In July 1984 a large decline in the abundance of other plankton
(including larval anchovies and cunner) was noted. The reasons for this 1984 decrease, which was observed
in other parts of eastern LIS (Richards, per. comm.), were not known, but during July 1984, ctenophores,
a plankton predator (Denson and Smayda 1982) were unusually abundant; a similar phenomenon may
have occurred in 1978.

Juvenile and adult tautog were present throughout the year in both impingement and trawl collections
but catches were higher May through October. Even though tautog prefer rocky shores such as those
surrounding MNPS intakes, they were not impinged in large numbers and contributed less than 1% to
the estimated impingement total (Table 8). Annual impingement estimates varied an order of magnitude,
from 122 in 1985 to more than 1,500 in both 1982 and 1983; the low estimate in 1985 may have been
related to a Unit 2 shut-down in June. More tautog were taken by trawl at nearshore stations (JC, IN
and NR) than at mid-bay (NB) and offshore (TT, BR) stations. Juveniles (fish smaller than 80 mm)
were taken by trawl primarily at NR (Fig. 23), which was an ideal nursery area (P. Briggs, per. comm.).
Smaller adult tautog probably stayed near the rocks and shoreline and thus were more susceptible to
impingement (Fig. 23). For similar reasons, these smaller fish were also abundant at JC. Because larger
tautog move to open water to feed, these individuals would be more likely to be taken by trawl at BR,
IN, NB and IT.

Because the numbers of tautog caught in trawl and seine samples were generally low and not
representative of their temporal distribution, the indices of egg and larval density were used for impact
assessment. Time-series models were fitted to the egg and larval data from the NUSCo plankton program.
All models had R^ values larger than 0.80 and included an annual cycle. The 1984 decline in larval
abundance is now a feature of the two-unit operational baseline models for both EN and NB. Summaries
of these models are presented in Appendices XXIV and XXV.

49

STATION-EGGS AT EN

O 20000

JAN OlFEB OlMAR 01APR 0 1 MAY 01JUN OIJUL OlAUG 0 1 SEP OlOCT O 1 NOV OlDEC 01.

MONTH

STATION-LARVAE AT EN

800

700
SOO
SOO
400
30O
200

JAN 01FEB OlMAR OlAPR 0 1 MAY 01JUN OIJUL 01AUG 01SEP 01OCT OINOV 01DEC 01

MONTH

STATION-LARVAE AT NB

1400

1 300

1 20O

1 TOO

1 000

300

SCO

700

SOO

SOO

400

300

200

"EB OlMAR OlAPR OlMAY 01

OlAUG OlSEP OlOCT OINOV OlDEC 0 1 J AN

Figure 22. Annual cumulative density (no./SOO m ) oftautog eggs at EN and larvae at EN and NB.

50

1 O O 200
FREQUENCY

SO 1 oo
FREQUENCY

TRAWLED AT JO

TRAWLED AT NR

TOO 200 300 4-00
FREQUENCY

SOO T 000
FREQUENCY

"RAWL ED — OTHER

MP I NGED

Figure 23. Taiitog length frequency.

Taiitogolabrus adspersus, cunner

The dinner {Tautogolabrus adspersus) is a coastal marine fish that prefers reef habitats (Bigelow and
Schrocdcr 1953; Serchuk 1972; 011a et al. 1975, 1979; Dew 1976; Pottle and Green 1975). It ranges from
northern Newfoundland to the mouth of the Chesapeake Bay (I^im and Scott 1966). Most cunner have
limited home ranges and are active only during the day (Green 1975). Activity declines in cold weather
and individuals become dormant at temperatures below 8°C and lie torpid among and under rocks (Green
and Farwell 1971; Dew 1976; Olla et al. 1979). The cunner becomes mature in its fu-st year (Dew 1976)
and spawns inshore from May through August (Wheatland 1956). Eggs are pelagic and usually found in

51

tlie upper 5 m of the water column (Williams 1967). Metamorphosis of larvae is complete by 10 mm and
juveniles move to the bottom (Miller 1958).

Gunner was found in all NUSCo programs, but it was most abundant in the plankton collections
(Tables 10, 12 and 14). It ranked among the top ten fishes in all collections except seines (Appendices V,
VIII, IX, X and XII).

Gunner eggs were the most abundant egg taxon entrained (Table 8) during the two-unit operational
period. Annual egg entrainment estimates ranged from 1,675x10^ (1981) to 2,589x10^ (1983) (Table 9).
Gunner egg density was lowest in either 1981 or 1982 depending on the abundance index used (median
or mean). The lowest median was 2,958/500 m in 1981 and the lowest mean was 1,761/500 m m 1982.
Similarly, egg density was highest in either 1983 (median = 5,934/500 m^) or 1985 (mean = 3,016/500
m^). Because the pattern of cunner abundance changed depending on the measure used, these data were
not useful for describing trends.

Gunner was the fourth most abundant larval fish at NB and fifth at EN. Abundance at NB was
higher than at EN in terms of both aimual cumulative density (Fig. 24)" and mean density (Tables 10 and
12). Further, temporal patterns at the two stations were different. Mean annual larval density was highest
at EN (13.8/500 m^) in 1981 and at NB (42.4/500 m^) in 1983. Both indices were lower in 1984 and
1985 than in any year since 1979, but no trend was apparent.

.luvenile and adult cunner were present primarily from May through November in impingement and
trawl collections; 25% of the total impingement catch occurred in .lune alone. Like tautog, cunner prefer
the rocky habitats that surround MNPS. Unlike tautog, however, cunner contributed more than 1% to
the total estimated impingment (Table 8). Annual impingement estimates varied an order of magnitude,
from 466 in 1985 to 3,851 in 1982. As it was the case for tautog, the low number of cunner impinged
during 1985 may have been related to the shut-down of Unit 2. Over 75% of cunner taken by trawl were
caught at IN and JG (Table 15). The spatial distribution of cunner was also similar to that of tautog
because both species have similar preferences and behavior. Although, juvenile cunner (individuals smaller
than 75 mm) stay near shore and thus were more likely to be taken by trawls at both NR and JG (Fig.
25), juvenile tautog were abundant only at NR (Fig. 23). Smaller adults also stay inshore and were likely
to be found in impingement collections; larger adults move offshore and were taken in trawls from deep

52

STATION— EGGS AT Ef'

20000
1 OOOQ

O 1 JAN O IFEE

IMAR OlAPR OlMAY OIJUN OIJUL OlAUG OlSEP OlOCT O 1 NOV 01DEC 01
MONTH

STAT I ON— LARVAE AT EN

JAN OlFEB OlMAR 01APR OlMAY OIJUN OIJUL OlAUG OlSEP OlOCT O 1 NOV OlDEC 01

MONTH

STATION-LARVAE AT NE

YEAR (19 )

O 2000

OIJAN OrFEB OlMAR OlAPR OlMAY OIJUN OIJUL OlAUG OlSEP OlOCT 0 1 NOV OlDEC OIJ/

Figure 24. Annual cumulative density (no./500 m ) of cunner eggs at RN and larvae at EN and NB.

53

zoo 40 O I
FR EQUENCY
TRAWLEP AT NR AND JC

500 1000 1500 2000
FREQUENCY
TRAWLED— OTHER

^OO lOOO TSOO 2000
FREQUENCY
I MP I NGED

Figure 25. length frequency of cunner.

water stations (Fig. 25). Although both total trawl catches (Table 14) and annual mean trawl catches
(Fig. 26) have declined since 1979, the other indices of cunner abundance (e.g., egg and larval densities)
did not follow the same trend. The precipitous drop of cunner larval abundance in 1984 could be explained
by the predation that also affected the abundances of tautog and anchovies that year. A previous drop in
cunner larval abundance in 1978, was followed in 1979 by the highest mean trawl catch (Fig. 26). None
of these fluctutations could be attributed to MNPS operations.

The time-series models described the seasonal variability of cunner catches reasonably well as indicated
by R values of 0.70 for plankton and 0.65 for impingement. All the models included an annual cycle
and the plankton models had an additional 4-mo cycle. The 1984 decline in larval abundance was well

54

described and is now a feature of the baseline model. Summaries of these models are presented in
Apr^ndices XXVI, XXVII, and XXVIII.

cr
u

n:
o

<

o

3

<

I I I I I I 1 i 1 1 —

76 77 78 79 80 81 82 83 84 85

YEAR

["igtire 26. Annual mean catch of cunner taken by trawl; the vertical bars are approximated 95% confidence intervals
for each year.

CONCLUSIONS

Impacts from the construction and operation of the Millstone Nuclear Power Station were assessed
during the operation of Units I and 2, using representative collections of fish assemblages. The composition
of these fish assemblages from January 1975 through December 1985 remained relatively stable, and was
typical of that reported for I ,IS by other researchers. Fish abundances exhibited predictable seasonal and
annual fluctuations; analyses indicated no adverse impact of two-unit operation. Data collected over the
past 10 yr provide an excellent baseline for assessing the possible impacts from the operation of three
power plants at MNPS.

55

SUMMARY

1. The construction and operation of the Millstone Nuclear Power Station (MNPS) could effect changes
in fish assemblages in several ways. Larger fish may be removed from the population by impingement
on the intake screens; eggs, larvae and small fish may be removed during entrainment through the
cooling water system; and spatial distribution of local fish populations may change in response to the
cooling water effluent.

2. Several programs were established to provide baseline data for assessing impacts of MNPS on fish
assemblages: entrainment, offshore plankton, trawl, seine and impingement monitoring programs. These
programs provided the data necessary for assessing the effects of two-unit operation and also provide
the baseline for three-unit impact assessment.

3. Over 100 taxa offish have been collected in the various Fish Ecology monitoring programs at MNPS
from January 1976 through December 1985. Eight taxa were selected for detailed analysis based on their
susceptibility to impact from impingement and entrainment: sand lance, anchovies, sticklebacks,
silversides, tomcod, grubby, cunner and tautog.

4. The abundance of these taxa varied both seasonally and annually in all programs and to separate
population fluctuations representing natural variability from those resulting from the construction and
operation of MNPS, a time-series approach was developed and applied to the monitoring data.

5. The abundance of potentially impacted taxa remained relatively stable throughout the 10-yr period,
except for larval and juvenile sand lance, and larval anchovy, cunner and tautog. Except for larval sand
lance, these abundance changes were short-term. Large annual fluctuations of sand lance have been
observed along the entire Atlantic coast. Thus the operation of two nuclear power plants at MNPS
has not adversely affected fish abundance, distribution or species composition in the Millstone area of
LIS.

56

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58

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59

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60

JefFries, H. P., and W. C. Johnson. 1974. Seasonal distributions of bottom fishes in the Narragansett
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l^im, A. H., and W. B. Scott. 1966. Fishes of the Atlantic coast of Canada. Bull. Fish. Res. Board
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I,und, W. A., and B. C. Marcy, Jr. 1975. Early development of the grubby, Myoxocephalus ae.naeus
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62

1981b. Feasibility of modifying the Millstone Units 1 and 2 cooling water intake screen wash

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63

. 1975. Activity, movements, and feeding behavior of the cunner, Tautogolabrus adspersus, and

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64

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65

Westin, D. T., K. J. Abemethy, I. E. Meller, and B. A. Rogers. 1979. Some aspects of biology of the
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Williams, G. C. 1967. Identification and seasonal size changes of eggs of the labrid fishes, Taulogolabnis
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Worgan, .1. P., and G. .1. Fitzgerald. 1981. Habitat segregation in a salt marsh among adult sticklebacks.
Env, Biol. Fish. 6:105-109.

66

Appendix la. Summary of gill net sampling program. Letters indicate station sampled T = Twotree; I = Intake; J = Jordan
Cove; C ^ Crescent Beach-Black Point; B = Bartlett Reef; N = Niantic Bay; E = East of effluent; W = West of effluent.

J

f|m|a|m|j |j |a|s

O 1 N

D

1971

(NOTE: The following sampling program began using a 6-panel net)

T-1^

1972

T-I^

T-.' 1

T-I^

r-i'

1973

T-I'

T-I-J-C'

T-I

j-c'

T-I

j-c'

1974

T-I-J-C'

1975

X^

T-I-J-C'
B-N-E-w"

T-I-J-C^; B-N-E-W" NOTE; changed to an eight-panel net
of varying mesh sizes starting in May.

1976

X^

T-I-J-B-N-E-W"

1977

T-I-J-B-N-E-W" 1

I-I-J-C-B-N-E-W''

1978

T-I-J-C-B-N-E-W"

1979 to
1982

T-l-J-C-B-N-E-W"

Indicates net was set at surface.
Indicates net was set at bottom.
Indicates a mid-water set.
X = Same a December of the previous year.

Appendix lb. Location of the gill net sampling sites.

67

Appendix II. Nuitiher of icthyoplanklon samples from various stations during I'JV.'i-IQSS.

F.ntrainment

stations

1973

1974

1975

1976

1977

1978

197<;

I98C

1981

1982

1983

1984

1985

I'olal

P.N

1S9

288

692

934

906

866

942

9,«

776

774

338

338

262

8241

IN

472

726

333

1 53 1

QCUT

189

288

132

609

Total

850

1302

1157

934

906

866

942

936

776

774

338

338

262

10381

OfTshore

stations

1973

1974

1975

1976

1977

1978

1979

I98f

1981

1982

1983

1984

1985

Total

Nn
1

79
86

124
119

155
91

21

20

28

209

238

236
96

238
38

142

128

119

1737
430

2
3

69
96

96
164

87
142

23

20
20

24

M

118

112

66

629
422

4

64

133

111

308

6

58

109

85

21

20

26

319

7

ino

175

163

438

8

70

128

155

21

20

31

425

9

94

142

114

3.50

10

72

124

142

3^8

II

152

144

23

20

33

372

12

85

78

163

13

88

92

.

180

14

51

154

21

20

28

274

15

76

3

20

99

Ifi

90

90

Tola!

788

1690

1879

133

160

170

223

356

444

342

142

128

119

6574

68

Appendix III. Number of olTshore ichlhyoplankton samples processed from NB for each month during 1973-1985.

Number of day samples

197.3 1974 1975 1976 1977 1978 1979

1981 1982 1983 1984 1985

1

15

1

1

2

4

4

4

4

2

2

40

2

10

10

1

1

2

4

6

8

6

2

2

53

3

8

12

1

1

4

6

4

8

4

2

3

54

4

10

8

1

5

16

16

16

12

10

10

10

115

5

2

8

15

3

? 4

20

20 .

16

16

9

8

8

132

6

12

10

12

4

? 4

16

20

16

20

9

8

8

142

7

8

10

11

3

? 4

20

16

20

16

8

10

8

137

8

13

13

6

3

? 4

16

16

20

20

10

8

10

142

9

8

11

8

1

1

3

4

4

4

4

4

2

55

10

10

10

3

1

1

2

6

4

4

2

6

3

53

II

9

8

3

1

1

2

4

4

4

3

2

2

44

12

4

12

3

1

1

2

4

4

4

2

2

2

42

Total

66

110

106

21

20 28 105 120

118

120

71

64

60

1009

Number oP night samples

Month

1973

1974

1975

1976

1977 1978 1979 1980

1981

1982

1983

1984

1985

Total

1

1

2

4

4

4

4

2

2

23

2

1 5

2

4

6

6

6

2

2

34

3

1 7

4

4

4

8

4

2

2

36

4

1 3

20

16

16

12

10

9

9

96

5

1 5

16

20

16

16

9

9

9

101

6 1

I 5

16

20

16

20

9

8

8

104

7 1

3 8

20

16

20

16

8

10

8

110

8 5

1 3

16

16

20

20

10

8

10

109

9 1

1 3

2

4

4

4

4

4

2

29

10 1

2 3

2

6

4

4

3

6

3

34

11 4

1 3

2

4

4

4

2

2

2

28

12

1 3

2

4

4

4

2

2

2

24

Total 13

14 49

104

118

118

118

71

64

59

728

69

Appendix IV. Number of entrainmenl samples processed from each month during 1976-1985.

Larval

samples

Month

'l976

1977

1978

1979

1980

1981

1982

1.983

1984

1985

lotal

1

77

84

78

84

81

72

72

34

36

10

628

2

72

72

71

72

75

72

72

32

34

13

585

3

84

8(1

34

78

78

78

84

38

34

33

621

4

78

75

57

75

78

81

78

32

34

36

624

5

78

78

84

84

78

75

72

34

37

36

6.56

6

7S

80

78

75

78

81

84

37

33

24

648

7

78

75

77

78

81

81

78

33

36

28

645

8

78

83

79

84

75

78

78

38

36

26

655

9

81

78

75

72

78

78

78

34

32

24

630

10

75

78

77

84

84

30

24

9

10

14

485

11

78

68

81

78

60

21

30

9

8

8

441

12

77

54

75

78

90

29

24

8

8

10

453

lolal

934

905

866

942

936

776

774

338

338

262

7071

Bgg samples

Month

1979

1980

1981

1982

1983

1984

1985

Total

4

78

81

78

32

34

26

329

5

84

78

75

72

34

37

28

408

6

75

78

81

84

37

-

33

24

412

7

78

81

81

78

33

36

28

415

8

84

75

78

78

38

36

26

415

9

72

78

78

78

34

32

24

396

lotal

!93

468

474

468

208

208

156

2375

70

Appendix V.
1976-1985.

Percentage contributed by each taxa to the estimates of total entrainment and impingement at MNPS during

Entrainment

Taxa

Eggs

Impingement

Anchoa spp.

Pseudopleuronectes americanus

Ammodytes americanus

Myoxocephalus aenaeus

Tautogotabrus adspersus

Pholis gunnellus

Brevoorlia tyrannua

Tautoga onitis

Syngnaihus /uncus

Liparis spp.

Ulvaria subbifurcata

Scophthalmus aquosus

Peprilus Uiacanlhus

Enchelynpus cimhrius

Prionotus spp.

Gobiidac

Stenolomus chrysops

Myoxocephalus octode.cemspinosus

Cynoscion regalis

Scomber scombrus

Anguilla roslrala

Paralichthys oblongus

Menidia spp.

Clupea harengus

Clupeidae

Urophycis spp.

Sphoeroides maculatus

Gadus morhua

Merluccius bilinearis

Microgadus tomcod

Paralichthys dentatus

Sciaenidae

Trinectes maculatus

Etropus microstomus

Gasterosteus aculeatus

Centropristis striata

Ophidian marginatum

Alosa spp.

Mentlcirrhus saxatilis

Lophius americanus

Osmerus mordax

Apeltes quadracus

Gadidae

Limanda ferruginea

Pollachius vlrens

Bothidae

Chaetodon ocellatus

Lumpenus lumprelaeformis

Cyclopterus lumpus

Gasterosteus wheattandi

Mugil cephalus

Hippocampus erectus

61.3

10.8

8.1

10.8

<0.1

8.5

9.7

<0.1

47.8

3.7

<0.1

5.9

1.8

55.5

1.9

1.8

0.0

0.1

1.8

<0.1

0.2

1.8

27,2

0.8

1.0

0.0

1.6

1.0

0.0

0.1

0.9

0.0

<0.1

0.7

1.4

0.9

0.7

<0,1

1.5

0.6

0.4

<0.1

0.3

2.2

0.2

0.3

0.0

0.0

0.2

1.0

0.1

0.2

0.0

<0.1

0.2

<0.1

0.2

0.2

<0.1

<0.1

0.2

0.0

0.2

0.2

<0.1

<0.1

0.1

0.1

5.5

0.1

<0.I

<0.1

0.1

0.0

<0.1

0.1

0.3

0.1

0.1

<0.I

0.2

0.1

<0.I

<0.1

0.1

0.0

1.6

0.1

0.0

3.4

<0.I

<0.1

0.2

<0.1

0.0

0.0

<0.1

<0.1

0.1

<0.1

0.0

<0.1

<0.1

0.0

5.1

<0.1

0.0

<0.1

<0.1

0.0

<0.1

<0.1

1.0

<0.1

<0.1

<0.1

<0.1

<0.I

0.0

<0.1

<0.1

0.0

0.4

<0.1

0.0

<0.1

<0.1

<0.1

<0.1

<0.1

0.0

0.0

:0.1

0.0

0.2

<0.1

0.0

0.0

<0.1

0.0

<0.1

<0.1

0.0

0.0

<0.1

0.0

0.5

<0.1

0.0

1.7

<0.I

0.0

<0.1

<0.1

0.0

<0.1.

71

Appendix V. (continued)

Entrainment

Taxa

Impingement

Pungiiius pungilius
Fundulus spp.
Conger oceaniais
Hemiiripterus americanus
Aleclis cUiaris
Alosa aestivalis
Alosa medlocris
Alosa pseudoharengus
Alosa sapidissima
Aluterus schoepft
Auloslomus macula tus
Bairdiella chrysoura
Brosme brosme
Caranx crysos
Caranx hippos
Chilnmyclerus schoepfi
Cyprinodon variegatus
Dactylopterus volitans
Decaplems macaretlus
Decaplerus punrlatiis
Etrumeus teres
Fistularia tahacaria
Hippocampus spp.
Ictalurus catus
Leiostomus xanthunis
Lepomis macrochinis
Macrozoarces americanus
Melanogrammus aeglefinus
Monacanlhus hispidus
Monocanthus spp.
Morone americana
Morone saxa tills
Mugit curema
Mustelis canis
Myoxocephalus spp.
Ophidiiaae
Ophidian welshi
Opsanus tau
Petromyon marinus
Pomatomus saltatrix
Priacanthus arenatus
Priacanthus cruentatus
Prisligenys alta
Raja spp.

Rhinoptera bonasus
Saimo tmtta
Selar cnimenopthalmus
Selene selapinnis
Selene vomer
Seriola zonata
Sphyraena borealis
Squahis acanthias
Trachurus lathami

<0.1

0.0

<0.1

<0.1

<0.1

0.1

<0.1

0.0

<0.1

<0.1

<0.1

O.I

0.0

0.0

<0.1

0.0

0.0

0.5

0.0

0.0

<0.I

0.0

0.0

0.2

0.0

0.0

<0.I

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

<0.i

<0.1

0.0

0.0

-:0.1

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

<0.1

0.7

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

0.2

0.0

0.0

<0.1

0.0

0.0

0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

0.5

0.0

0.0

<0.1

0.0

0.0

<0.I

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

0.0

0.0

<0.1

72

Appendix VI. Annual mean fish larval density (no./SOOm ) at EN during 1976-1985.

Taxa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Mean

Anchoa spp.

185.2

178.2

72.0

313.3

346.7

550.5

182.3

301.7

66.3

245.2

244.1

Pseudopleuronectes americanus

42.0

27.6

31.0

26.8

59.5

31.4

59.2

70.6

45.9

36.2

43.0

Ammodytes americanus

10.8

55.2

110.8

50.6

65.7

52.8

12.4

13.4

8.3

4.7

38.5

Myoxocephalus aenaeus

4.7

11.7

7.1

10.7

11.2

25.5

20.8

20.5

16.0

19.9

14.8

Taulogolabnis adspersus

5.6

12.1

0.4

3.2

12.4

13.8

8.6

12.5

1.0

2.8

7.2

Pholis gunnelius

2.4

5.1

4.3

6.3

5.5

18.5

10.9

5.1

5.9

7.3

7.1

Brevoortia tyrannus

2.9

1.8

2.1

0.4

1.9

1.6

7.5

19.9

1.9

30.6

7.1

Tautoga onitis

7.0

8.5

0.4

2.5

9.3

16.7

11. 1

9.5

0.8

4.5

7.0

Syngnathus fuscus

1.5

3.5

2.2

8.5

3.4

6.1

3.2

4.7

4.0

2.7

4.0

Uparis spp.

1.1

6.1

5.9

2.4

4.2

4.7

1.3

3.2

1.9

7.7

3.8

Ulvaria subbifurcata

3.5

1.3

1.9

2.9

3.6

3.8

4.3

1.9

1.0

11.8

3.6

Scophthalmus aqiiosu!

4.0

6.0

0.7

2.2

2.5

2.9

1.5

7.0

1.7

0.6

2.9

Peprilus trtacanthus

4.7

1.1

0.4

0.5

9.9

4.7

3.1

3.0

0.4

0.7

2.8

Enchelyopus cimbrius

1.2

2.5

1.8

2.1

1.9

0.5

2.3

4.7

1.7

3.0

2.2

Prionotus spp.

0.8

0.6

0.1

0.3

0.9

5.2

0.3

1.6

0.2

2.0

1.2

Gobiidae

2.9

2.0

0.7

0.2

0.7

0.1

0.3

0.7

2.2

1.8

1.2

Stenolomus chrysops

1.1

1.8

O.I

1.0

I.l

2.0

0.4

0.0

<0.1

<0.I

0.7

Myoxocephalus octodecemspinosus

0.2

0.3

0.2

0.3

0.3

0.5

1.1

2.2

1.5

0.7

0.7

Cynoscion regatts

0.2

0.7

<0.1

1.2

<0.1

1.5

1.6

0.8

0.1

0.5

0.7

Scomber scombrus

0.6

3.7

O.I

0.1

0.1

<0.I

<0.I

1.3

<0.I

0.3

0.6

Anguilla rostra ta

0.4

1.9

l.I

1.0

0.2

0.3

0.3

0.4

0.2

O.I

0.6

Paralkhthys oblongus

0.6

0.8

O.I

0.1

0.1

0.8

1.3

0.4

0.4

1.0

0.6

Menidia spp.

0.5

0.1

0.5

0.6

0.5

0.4

0.2

2.2

0.1

0.3

0.5

Clupea harengus

O.I

0.3

0.2

0.4

<0.1

2.0

0.3

0.0

0.2

0.3

0.4

Clupeidae

<0.I

0.6

0.3

0.4

0.2

0.1

<0.I

0.4

O.I

0.0

0.2

Urophycis spp.

0.9

0.1

<0.I

<0.1

<0.1

0.8

<0.I

0.1

<0.1

0.2

0.2

Sphoeroides maculatus

0.6

0.2

0.0

<0.1

<0.I

O.I

0.2

0.2

<0.I

0.5

0.2

Gadus morhua

0.1

<0.1

<0.I

<0.I

O.I

I.l

0.2

0.2

<0.1

<0.1

0.2

Paralkhthys dentatus

0.1

<0.1

O.I

O.I

0.2

O.I

O.I

0.3

<0.1

0.3

0.1

Merluccius bilinearis

0.4

0.2

<0.I

O.I

0.2

O.I

<0.1

O.I

0.1

0.1

0.1

Microgadus tomcod

0.1

0.1

0.1

0.1

<0.I

O.I

0.3

0.2

0.1

0.1

0.1

Sciaenidae

<0.1

0.0

<0.1

0.0

<0.I

I.O

0.0

<0.1

<0.1

0.1

0.1

Trinectes maculatus

0.1

0.2

0.0

<0.I

<0.1

0.6

<0.1

O.I

<0.1

0.0

0.1

Etropus microstomus

0.3

O.I

<0.1

<0.1

0.1

0.1

<0.I

0.1

O.I

<0.1

0.1

Gasterosleus aculeatus

0.1

0.1

0.2

0.1

<0.1

<0.1

<0.I

<0.1

0.0

0.0

0.0

Centroprlstis striata

0.1

O.I

<0.1

<0.1

0.1

0.1

0.0

0.0

<0.I

0.0

0.0

Ophidian marginatum

0.2

<0.I

0.0

0.0

<0.1

0.0

0.0

0.0

0.1

<0.1

0.0

Alosa spp.

0.0

0.0

<0.1

0.1

<0.1

<0.1

0.0

0.1

0.1

0.0

0.0

Menticirrhus saxatilis

<0.1

0.0

0.0

0.0

0.0

0.2

0.0

0.0

0.0

0.0

0.0

Lophius americanus

0.0

0.0

0.0

<0.1

0.2

<0.1

0.0

0.0

<0.I

0.0

0.0

Osmerus mordax

<0.1

O.I

<0.1

<0.1

<0.1

<0.1

0.1

0.0

0.0

0.0

0.0

Apeltes quadracus

<0.1

<0.1

<0.1

0.0

<0.1

<0.1

0.0

<0.1

0.0

0.2

0.0

Gadidae

<0.1

0.1

<0.1

<0.1

<0.1

0.1

0.0

<0.I

<0.1

<0.1

0.0

Limanda ferruginea

0.2

<0.1

<0.1

<0.I

<0.1

<0.1

<0.I

<0.I

<0.1

<0.I

0.0

Pollachius virens

<0.1

<0.1

<0.1

0.0

<0.1

<0.1

<0.I

O.I

<0.1

<0.1

0.0

Bothidae

0.0

0.0

0.0

0.0

0.0

0.0

<0.I

0.0

0.0

0.0

<0.I

Chaelodon ocellatus

0.0

0.0

0.0

0.0

<0.1

0.0

0.0

0.0

0.0

0.0

<0.1

Lumpenus lumpretaeformis

0.0

0.0

0.0

<0.1

0.0

0.0

0.0

0.0

0.0

0.0

<0.1

Cyclopterus lumpus

0.0

0.0

0.0

0.0

0.0

<0.1

0.0

<0.1

0.0

0.0

<0.1

Mugil cephalus

<0.1

<0.1

0.0

0.0

0.0

<0.1

0.0

0.0

0.0

0.0

<0.1

Hippocampus erectus

<0.1

0.0

0.0

0.0

<0.1

0.0

<0.1

0.0

0.0

<0.1

<0.1

Pungitius pungitius

0.0

0.0

<0.1

<0.I

'0.0

<0.1

<0.1

0.0

0.0

0.0

<0.1

Fundulus spp.

<0.1

<0.1

<0.1

<0.I

0.0

<0.1

<0.1

<0.I

0.0

0.0

<0.1

Conger oceanicus

<0.1

<0.1

<0.1

<0.1

<0.1

<0.1

<0.1

0.0

<0.1

<0.1

<0.1

Hemitriplenis americanus

<0.1

<0.1

<0.!

<0.!

<0.1

<0.1

<0.I

<0.1

<0.1

<0.1

<0.1

Total

288.4

335.9

246.5

440.0

544.6

752.2

336.8

490.0

163.8

387.2

398.5

73

Appendix VII. Annual mean Hsh larval density (no./500 ) at NB during 1979-1985.

Taxa

1979

1980

1981

1982

1983

1984

1985 Mean

Anchoa spp.

320.7

418.2

494.1

292.5

485.3

62.9

239.3 330.4

AmmodytPS amerlcanus

56.2

52.4

174.9

9.4

40.9

27.9

11.4

53.3

Pseudopleuronectes amerlcanus

19.0

42.9

26.8

43.1

68.4

41.8

44.2

40.9

Taulogolabn/.'i adspersus

19.6

24.9

17.6

34.4

42.4

7.9

8.0

22.1

Tauloga onilis

10.6

17.3

18.4

27.8

28.3

6.7

11.3

17.2

Myoxocephalus aenaeus

6.1

9.1

13.0

11.2

11.8

9.6

11.9

10.4

Brevoorlia lyrannus

0.6

1.9

2.4

36.1

9.8

9.6

6.9

9.6

Scnphlhalmus atjunsus

8.3

5.8

3.0

10.6

12.2

5.7

3.6

7.0

Pholis gunneltus

4.6

3.6

12.1

6.6

3.8

6.4

4.5

5.9

Pepritus triacanlhus

1.9

5.3

6.9

10.4

11.5

0.8

4.7

5.9

Enchelyopus dmbrius

6.2

2.6

1.1

6.8

6.3

8.8

5.5

5.3

Syngnathus fusojs

2.7

3.2

3.7

2.4

6.5

3.6

1.5

3.4

Prionolus spp.

1.3

1.5

8.4

5.1

4.5

0.9

1.7

3.3

Liparis spp.

1.8

2.3

3.9

0.9

3.0

0.8

6.3

2.7

Ulvaria mbbifurcata

1.3

2.2

2.2

4.8

1.9

1.4

2.9

2.4

Myoxocephalus octndecemspinosus

0.5

1.3

2.3

2,0

3.1

3.9

1.6

2.1

Parallchthys oblongus

0.2

0.6

1.7

1.9

3.0

0.2

1.6

1.3

Cynoscion regalls

1.6

0.1

2.3

3.7

0.1

0.0

0.3

1.2

Stenntomus chrysops

2.1

4.0

1.4

0.4

0.1

<0.I

<0.I

0.9

Scomber scombnts

1.6

0.3

<0.1

0.9

1.0

0.5

1.0

0.7

Merlucclus bUlnearis

0.5

0.5

0.4

0.4

0.2

0.4

0.7

0.4

Parallchthys dentatus

0.2

0.2

1.2

0.1

0.2

0.3

0.2

0.3

Clupeidae

0.1

0.1

O.I

0.0

<0.1

•-0.1

3.4

0.3

Gobiidae

0.2

0.0

0.1

0.2

0.5

0.4

0.3

0.2

Sciaenidae

<0.1

0.0

1.2

0.4

1.1

<0.1

0.1

0.2

Clupea harengus

0.1

0.0

1.0

0.2

0.1

<0.1

0.6

0.2

Fjropus mkrostomus

0.0

0.0

0.1

0.2

0.3

0.1

0,2

0.1

Gadus morhua

<0.l

<0.1

1.3

0.1

0.5

0.3

0.1

0.1

Menldla spp.

0.4

0.2

0.6

0.0

0.6

<0.1

<0.1

0.1

Alosa spp.

0.1

<0.I

0.2

0.0

0.4

0.1

0.2

O.I

Pomalomus sallalrix

0.0

0.0

0.0

0.0

0.0

0.0

0.1

O.I

Sphoeroldes maculatus

0.2

0.1

0.1

0.1

<0.1

O.I

0.1

O.I

Angullla rostrata

0.1

0.1

0.1

0.1

<0.1

0.1

O.I

0.1

Centroprislls striata

<0.1

<0.1

0.2

0.0

1.0

0.0

0.0

O.I

Urophycls spp.

0.1

<0.l

0.6

0.2

<0.1

0.1

0.2

0.1

Pollachlus vlrens

0.0

0.0

0.0

0.0

O.I

0.1

<0.1

0.1

Cyclnpterus lumpus

0.0

0.0

<0.l

o.n

0.0

0.0

0.0

0.1

T'undulus spp.

0.0

0.0

<0.1

0.0

0.0

0.0

0.0

O.I

Hippocampus e.rectus

0.0

0.0

0.0

0.0

0.0

0.0

-0.1

0.1

Microgadus tomcod

<0.1

0.1

0.2

0.1

0.1

<0.1

0.1

0.1

Gadidae

0.0

O.I

0.0

•-n.i

<0.1

0.1

0.0

0.1

Conger nceanlcus

<0.1

0.0

0.0

0.0

<0.I

O.I

0.0

0.1

Ijophius amerlcanus

<0.1

0.0

0.0

0.1

<0.I

0.0

0.0

0.1

Castp.rnsteus aruleatus

<0.1

0.0

<0.1

0.0

0.0

0.0

0.0

O.I

Osmerus mnrdax

<0.1

0.0

0.0

-0.1

0.0

0.0

0.0

0.1

Ophidian marginatum

0.1

<0.1

<0.I

0.0

O.I

<0.I

0.4

0.1

'/"rlnectes mantlatus

0.0

0.0

0.4

■'0.1

<0.I

0.0

<0.I

O.I

Uemltrlpterus amerlcanus

0.0

<0.1

•;0.I

0.1

<0.1

0.0

0.0

O.I

limanda ferruglnea

<0.l

<0.1

<0.l

<0.l

O.I

0.2

O.I

O.I

lotal

A6f>.\

(501.1

SM.O

5H.1

749.4

50 1. '5

^m ^

W.5

74

Appendix VIII. Annual mean fish egg density (no./500m ) at EN during April through September of 1979-1985.

Taxa

1979

1980

1981

1982

1983

1984

1985

Mean

Tautogolahru.i ad^pnrsu.t

2454.5

2898.5

1908.9

1761.6

2001.2

2240.7

3016.3

2326.0

Tautoga onitis

714.6

1311.4

1273.9

1033.5

999.2

1122.0

1507.5

1137.4

Anchoa spp.

413.0

306.1

339.4

218.4

636.7

1196.9

53.2

452.0

Prionotus spp.

30.4

75.6

115.5

.118.3

133.2

51.9

112.2

91.0

Scophlhalmus aquosyx

34.5

41.4

53.4

24.6

17.3

41.9

208.9

60.3

Alosa spp.

267.3

0.3

0.2

14.6

0.0

on

0.0

40.3

Slenniomus chrysops

10.6

0.3

63.6

53.3

45.9

95.4

11.6

40.1

Enchelyopm cimhrius

14.2

9.5

17.4

31.6

7.7

8.9

16.3

15.1

Urophycis spp.

2.0

6.5

23.5

1.7

14.3

30.8

21.7

14.4

Menidia spp.

0.0

3.4

1.5

0.3

0.7

19.8

<0.l

3.7

Rrevoortia tyrannus

0.8

<0.1

0.5

0.6

2.0

6.4

3.8

2.0

Cynoscion regalis

4.9

3.0

1.3

0.0

0.0

0.0

0.0

1.3

Scomber scombrus

5.2

0.5

0.0

2.2

0.0

0.0

0.0

1.1

Pseudoplfnironectes americanus

0.8

0.9

4.7

1.1

0.3

0.0

0.0

1.1

Trinectes maculams

5.8

0.0

0,1

0.0

0.0 •

0.0

0.0

0.8

Ilemitriptcrus americanus

0.0

0.0

0.0

4.9

0.0

0.0

0.0

0.7

Myoxocephalus aenaeus

3.2

<0.1

<0.1

0.9

<0.1

0.0

0.5

0.6

Peprilus triacanthus

0.7

1.1

0.0

0.0

0.0

0.0

n.o

0.3

Paralichlhy.r oblongus

0.2

0.5

0.0

0.5

0.0

0.0

0.0

0.2

Cyprmndon varingatus

<0.1

0.0

0.0

0.7

0.0

0.0

0.0

0.1

Paralichlhys dentatiia

0.0

0.1

0.0

0.3

0.0

0.0

0.0

0.1

Ammodyles americanus

0.3

0.0

0.0

0.0

0.0

0.0

0.0

<0.1

Fundutus spp.

0.3

0.0

0.0

<0.1

. 0.0

0.0

0.0

<0.1

Morone americana

0.0

0.0

0.0

<0.1

0.0

0.2

0.0

■-0.1

Myoxocephalus octodecemspinosus

0.1

0.0

0.0

0.0

0.0

0.0

0.0

<0.1

Clupea harengus

<0.1

0.0

0.0

0.0

0.0

0.0

0.0

•■0.1

Sphoeroides marulatus

<0.1

0.0

0.0

0.0

0.0

0.0

0.0

<0.1

Gadidae

0.0

<0.1

<0.I

<0.1

<0.1

0.0

-o.i

<0.1

Gadus morhua

<0.1

<0.1

<0.1

<0.1

<0.1

0.0

0.0

<0.1

Total

3963.6

4659.1

3803.9

3269.1

3858.7

4814.9

4952.2

4188.8

75

Appendix ?X. Annual impingement estimate for all taxa impinged, calculated using flows From 0800-0745 (Units 1 & 2 combined
by year except during 1984-85 when Unit 2 was estimated alone).

Fish Taxa

1976

1978 1979 1980

1984 1985 Total

Ammndytes spp.

65

69

277

98

192

269

136

449

485411

73

487039

Psmdopletironectes americanuY

5654

7622

7676

23544

7207

7640

8875

13467

2542

2765

86992

Anchoa spp.

5606

804

869

3340

4426

4755

5895

52280

4200

342

82517

Myoxocephalus aenaeus

2108

2357

7528

3699

10736

5450

6486

14634

23 59

4553

59866

Menidia spp.

1585

1328

12155

12187

10199

3733

3872

8136

1042

1480

55717

Micrngadus tomcod

91

339

2398

1455

1314

8121

11868

2860

4938

1129

34513

Gasterostms spp.

2411

5375

5511

9918

7441

30656

Ga.itero.iteux aculealus

6817

2951

9472

1055

852

21147

Taulngolabms adsp^rsus

903

1429

1862

3110

1157

2566

3851

2900

1188

466

19432

Casterosteus wheatlandi

601

1393

14381

702

21

17098

Syngnathus fuscus

643

384

1265

1289

1152

1611

1029

6572

1467

456

15868

Merlucclus bilinearis

791

1086

545

837

1703

679

560

9419

133

105

15858

Peprilus triacanthus

135

149

298

1574

1139

1829

4061

3086

1455

1336

15062

Scophthalmus aqunsus

679

454

406

1024

1122

640

743

3401

569

173

9211

Tautoga onitis

883

809

1074

866

338

814

1579

1512

664

122

8661

Morone americana

312

761

670

368

643

598

2540

912

375

48

7227

Cydoptenis lumpus

47

525

781

578

1301

329

11

859

120

1010

5561

Alosa aestivalis

121

221

207

381

162

280

125

3605

91

51

5244

Raja spp.

499

271

240

337

453

531

507

1468

275

98

4679

Osmems mordax

399

337

658

476

175

438

492

1479

71

97

4622

Brevoortia tyrannus

200

159

104

187

222

165 .

306

682

167

242

2434

Paralichthys denlatus

463

127

87

14

80

390

349

241

646

29

2426

A iosa pseudoharengus

97

359

52

255

156

223

273

659

79

59

2212

Sphoeroides maculatiis

289

153

34

61

49

130

469

712

174

86

2157

rrinnolvs spp.

503

226

96

89

87

323

255

223

49

72

1923

Cynoscion regalis

31

886

84

10

12

632

58

90

34

14

1851

Anguilla rostra ta

99

210

76

180

115

114

486

379

60

48

1767

Pnllacliius virens

9

19

11

2

89

164

161

888

253

0

1596

Opsanus tau

163

103

167

169

155

228

214

246

98

28

1571

Ijparis spp.

9

308

188

48

53

371

55

272

39

66

1409

Fundutus spp.

58

75

464

97

98

340

138

80

20

8

1378

Pomatomus saltatrix

53

133

14

206

55

192

65

459

no

46

1333

Slenotomus chrysnps

153

118

30

139

48

101

213

343

53

105

1303

Ifrntitriplprus amrricanus

12

20

11

35

56

132

240

365

22

6

899

Pholis gunnpllus

72

39

78

111

67

119

100

247

49

12

894

Trinectes maatlatvs

28

15

30

119

55

61

139

88

194

21

750

Urophyds chuss

7

18

2

115

33

51

47

198

71

13

555

Urophyds regia

5

0

0

3

18

24

25

444

1'

0

526

Clupea harengus

60

128

0

5

2

77

21

48

12

12

365

Caranx hippos

6

0

2

6

2

76

134

76

21

34

357

Morone saxatilis

4

10

3

11

0

4

235

67

0

7

341

Melanogrammus anglefmus

0

0

6

307

7

0

0

0

0

0

320

Gadus morhiua

0

0

0

0

n

10

65

74

142

7

298

Monaranlhus hispidus

6

30

50

118

8

6

11

7

3

9

248

76

Appendix IX. (continued)

Fish Taxa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Total

Etropus mkrostomus

Urophycis spp.

Mugil ce.phalus

Alosa sapldlssima

Myoxocephalus spp.

Leioatomus xanthunis

Centropristis striata

Sphyraena horealis

Ophidian marginatum

App.ltes quadracus

Paralichthys ohlongus

Urophycis tenuis

Scomber scomhrus

Selene setapinnis

Aluterus schoepfi

Selene vomer

Mustelis canis

Ulvaria subbifurcata

Conger occanicus

Caranx crysos

Mugil atrema

Pungitius pungitius

Alectis ciliaris

Chaetodon orellatus

Myoxocephalus octodecemspinosus

Squalus acanlhias

Trachurus lalhami

Ophidiidae

Fistularia tabacaria

Cyprinodon variegatus

Rairdiella chrysoura

Dactylopterus votitans

Fjrumeus teres

Gadidae

Hippocampus erectus

iMphius americanus

Chilomycterus schoepfi

Derapterus macarellus

Pristigenys alta

Decapterus punctatus

Menticirrhus saxa tills

Alosa spp.

Priacanthus arenatus

3 5 0

0 34 190
8 13 23

12 1 0

1 203 0

16 4 152
316 0
12 4 12
26 0 0

2 5 8
50 15 6

0 2 II

3 4 5

30 0 0

1 57 6
0 37 4

2 II 34
6 5 9

17 8 0
0 13 7
0 0 0

0 0 2

1 7 2
0 0 4
0 0 3

2 0 0
0 0 0

31 0 0

3 4 5
0 0 13
0 0 0
0 2 0
0 2 0
0 0 5
2 0 0
0 0 0
0 2 3
0 0 0
0 0 0
0 0 0
0 0 4
0 0 0
0 0 0

0

6

5

9

178

20

10

236

4

2

2

0

3

0

0

235

11

37

37

9

34

39

4

215

5

33

33

25

82

16

0

207

0

0

0

0

0

0

0

204

0

0

0

2

28

0

0

202

0

9

2

12

54

74

0

188

0

0

35

71

2

12

0

148

10

0

0

9

31

50

6

132

10

33

48

14

5

2

0

127

14

6

16

2

7

0

6

122

0

6

17

30

6

45

0

117

17

9

12

48

9

0

0

107

0

0

0

2

6

20

34

92

0

3

6

9

0

6

0

88

0

5

0

2

4

14

22

88

12

n

6

7

5

0

8

85

13

0

7

7

26

6

4

83

0

2

2

9

31

0

0

69

0

0

5

14

4

24

0

67

0

0

24

0

7

27

8

66

0

0

6 ■

21

22

5

10

66

0

3

30

2

0

6

7

58

0

0

4

12

26

0

7

53

5

5

14

7

10

0

0

44

3

6

2

0

31

0

0

44

32

0

4

0

4

0

0

40

0

0

0

5

0

0

0

36

0

10

2

5

0

0

6

35

0

4

2

5

9

0

0

33

0

0

0

2

24

0

0

26

0

0

2

10

3

0

7

24

19

0

0

2

0

n

0

23

0

2

0

13

0

0

0

20

0

0

2

0

11

0

3

18

0

2

0

9

0

0

7

18

0

0

2

2

0

8

0

17

0

0

0

0

0

15

0

15

0

0

0

2

n

12

0

14

0

0

4

7

2

0

0

13

5

0

0

2

2

0

0

13

0

0

0

5

0

6

0

11

0

0

0

5

0

6

0

11

77

Appendix IX. (continued)

Fish Taxa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Total

rriacanlhus rnientatus

0

0

0

0

n

2

0

9

0

0

11

\facrozoarres amerkanus

0

0

0

2

n

0

0

2

0

6

10

Seriota lonata

0

9

0

0

0

0

0

0

0

0

9

Enchelyopus cimhrius

0

0

0

0

0

0

0

0

8

0

8

Monocanthus spp.

0

0

0

0

0

0

2

3

3

0

8

Clupeidae

0

0

0

0

0

0

0

0

3

4

7

Hippocampus spp.

0

0

0

0

0

0

0

■ 0

0

6

6

Salmo trutta

1

0

0

5

n

0

0

0

0

0

6

Selar crumenopthalmus

3

0

0

0

0

2

0

0

0

0

5

Alosa medincris

n

0

0

0

0

0

2

2

0

0

4

Ictalurus cams

2

0

0

0

0

0

2

0

n

0

4

Ophidinn welshl

0

0

0

0

0

2

0

2

0

0

4

Aulnstnmus maailatids

3

0

0

0

0

0

0

0

0

0

3

Brosme hrosme

I

0

0

0

0

0

0

2

0

0

3

l.epomis macrochirus

0

0

0

0

0

0

0

2

0

0

2

Petromynn rnannus

0

0

0

0

2

0

0

0

0

0

2

Rhinoplera bonasus

0

0

0

0

0

2

0

0

0

0

2

Total

25528

27909

46517

67535

52512

51973

61436

158468

511387

16266

1019531

Invertebrate Taxa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Total

Inligo pealei

138.36

4482

4493

22124

18763

13725

19521

24109

14748

3291

139092

Ovalipe.s ncellatiis

1845

4337

3050

11258

17912

22686

31952

17574

4118

2833

117565

Cancer irroratus

830

633

751

681

684

6058

7925

7137

6680

4448

35827

Carcinus maenus

989

781

656

765

912

3732

2533

6687

5647

2717

25419

CalUnertes sapidus

939

437

928

1901

1963

1802

1433

1553

1020

732

12708

Hnmanis ameriranus

1141

544

508

718

761

1715

1967

1504

1167

501

10526

Libinia spp.

1598

526

157

119

235

795

865

1360

1484

406

7545

Ncnpannpe texana

0

35

35

28

25

167

785

626

1496

242

3439

IJmulus polyphemiu

327

59

45

64

89

184

142

162

164

0

1236

Squitla e.mpusa

53

67

6

2

193

34

29

178

3

3

568

Pagurvs spp.

227

45

21

4

91

45

18

14

12

7

484

Cancer borealis

18

6

7

100

26

37

25

42

2

0

263

Upngebia afftnis

0

0

0

0

0

0

14

128

0

0

142

Argopnctpn irradians

0

0

0

0

0

5

2

50

38

0

95

IUpx illprrhrosus

0

19

10

n

0

29

7

5

6

0

76

rrnaeus azirciis

0

0

0

n

4

2

47

0

0

7

60

Callinassa atlandcus

0

0

0

0

0

0

0

34

0

0

34

Callinectes siniilis

0

0

0

0

0

7

18

0

0.

0

25

Lunatia heros

0

0

2

0

2

0

7

0

0

0

11

Aplysia wilroxi

0

0

0

0

2

0

0

0

0

0

2

Uexapanopnis angustifrons

1

0

0

0

0

0

0

0

0

0

1

Total

21804

11971

10669

37764

41662

51023

67290

61163

36585

15187

355118

78

Appendix X. Trawl catch by year (1976-1985).

W6

1977

1978

1979

1980

1981

198 J

1983

1984

1985

Total

Number of samples

908

936

936

936

972

935

936

936

936

936

9367

Fish Taxa

Psmdopleuronectes ameriranus

7875

5752

6055

10694

12378

13124

13517

16799

14027

8869

109090

Stenotomus chrysops

2209

4040

2556

4052

3882

3401

4878

5286

4109

2732

37145

Scophthalmux aquosus

1618

1259

736

1408

2133

1549

2745

2970

2339

1951

18708

Anchoa spp.

980

580

2223

15

113

577

39

88

178

9997

14790

Raja spp.

875

541

409

404

728

819

1819

2602

2067

2402

12666

Gadidae

29

231

647

438

391

6627

1424

429

455

698

11369

Menidia spp.

2151

1224

1060

2059

1003

356

427

635

348

465

9728

Tautngotabrus adspp.rnis

1009

1032

359

1381

981

825

561

412

246

143

6949

Myoxocephalus aenaeus

191

276

591

316

458

866

788

904

595

498

5483

Prionotus spp.

370

333

105

341

389

535

1176

411

369

317

4346

Paralichlhys den laws

309

149

89

79

120

232

244

266

1929

210

3627

Merlucdus bilinearis

385

141

102

169

533

217

391

135

109

175

2357

Urophyds spp.

194

97

55

102

161

215

356

626

216

231

2253

Tautoga onitis

251

292

246

283

138

235

228

159

110

136

2078

Uemitriptems ameriranus

31

41

35

82

223

347

381

581

262

72

2055

Microgadus lomcod

19

25

40

49

125

279

1147

132

90

85

1991

Casterostmts aculeaius

19

22

13

103

38

192

116

256

940

199

1898

Phnlis gunnellus

24

147

62

100

145

301

206

290

130

156

1561

Syngnathus fuscus

49

34

58

71

127

288

158

241

262

181

1469

Peprilus Iriacanthus

37

42

408

173

46

69

182

244

17

134

1352

Osmerus mordax

121

242

102

39

110

49

62

83

221

319

1348

Apeltes quadracus

19

7

5

24

32

196

764

77

22

119

1265

Cadus morhua

3

29

3

2

0

I

26

255

278

348

945

Myoxocephalus octodecemspinosiis

43

12

23

92

42

110

117

126

34

24

623

Etropus mkrostomus

52

6

3

3

26

80

54

88

96

124

532

Paralichlhys oblongus

31

8

21

7

53

31

109

54

87

58

459

Ammodytes americanus

1

4

60

127

37

117

14

19

10

19

408

Alosa pseudoharengus

9

38

243

9

18

11

7

6

23

4

368

Opsanus tau

102

22

6

17

32

35

21

28

18

34

315

Centropristis striata

34

9

3

4

10

63

22

39

26

66

276

Anguilla rostrata

20

17

7

6

10

35

28

26

22

32

203

Pollachius virens

1

3

0

19

0

5

33

36

87

19

203

Cyrlopterus lumpus

2

17

13

28

56

11

1

14

0

29

171

Uparis spp.

8

8

26

12

19

12

35

9

15

11

155

A losa sapidissima

32

6

2

3

42

9

3

28

1

0

126

Ciupeidae

2

1

0

0

0

0

0

0

0

110

113

Chipea harengus

5

1

9

13

0

1

0

1

6

67

103

Cynoscion regalis

9

21

4

2

2

45

4

3

1

5

96

Sphoeroides maculatus

17

10

1

0

9

14

16

15

6

8

96

Mustelis canis

2

5

45

11

1

5

4

6

0

2

81

Alosa aestivalis

5

0

12

10

13

1

0

8

11

5

65

Brevoortia tyrannus

1

4

11

10

2

1

0

0

1

34

64

Umanda ferruginea

0

7

5

6

1

9

10

5

1

3

47

Monacanthus hispidus

3

6

8

4

0

0

8

1

8

9

47

Morone americana

4

7

15

3

11

3

1

1

0

0

45

Macrozoarces americanus

0

5

8

8

3

3

0

2

2

3

34

Goblidae

3

0

0

0

4

0

0

3

2

13

25

Fislularia labacaria

2

3

0

0

3

0

1

0

8

1

18

79

Appendix X. (continued)

Fish Taxa

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Tolal

Leiostomus xanlhunis

3

2

6

rt

0

f)

0

5

0

i

15

Gasterosteidae
Pomatomus sallatrix
Hippocampus spp.
Aluterus schoepfi
Dactyloptenis volitans
Synodus foeiens
Pungitius pungitius
Fundulus spp.
Priacanlhus cruentatus
Menlicirrhus saxatilia
Morone saxaiiUs
Caranx crysos
Lnphius americanus
Trinectes maculatus
Ulvaria suhbifurcata
Conger oceanicun
Prisligenys alta
Sphyraena borealis
Trachurus lathami
Gasterosleus wheatlandi
Lactophrys spp.
Mullus auratus
Ophidion marginatum
Priacanlhus arenatus
Selene vomer
Alosa mediocris
Caranx hippos
Chaetodon ocellatus
Decapterus macarellus
Mugil cephalus
Scomber scombrus
Squalus acanthias
Acipenser oxyrhynchus
Auloslomus maculatus
Bairdiella chrysoura
Bothus ocellatus
Dasyatis centroura
Enchelyopus cimbrius
Melanogrammus aeglefinus
Mylioba tis fremin villei
Salmo Irutta
Scyliorhinus retifer
Selar crumenoplhalmus
Selene sctapinnis
jyachinocephalus myops
Trachinotus fakatus
Upeneus parvus
Total

19174 \6161 1(5505 nm lA^^ ,51951 35147 54417 MSi5 .'il l44 i59M.5

80

Appendix X. (continued)
Invertebrate Taxa

"TT75 TTTT ITTS m^ m^

iwi rm — rm — mi Total

Libinia spp.
Carcinus maenus
Cancer irroratus
Loligo pealei
Lunatia heros
Ovalipes ocellatus
Homarus americanua
Argopecten ir radians
Libinia spp.
Pagurus pollicaris
Neopanope texana
Asterias forbesi
Callinecles sapidus
Umulus polyphemus
Busycon canaliculatum
Cancer borealis
Cancer spp.
Busycon carica
Polinices duplicata
Squilla empusa
Callinectes similis
Henricia sanguinolenta
[Ilex illecebrosus
Total

1268

3832

339

331

1991

2177

1822

2856

2932

3206

20754

276

86

58

81

805

1643

3152

1203

2539

2965-

12808

91

91

193

142

469

1713

2112

5530

828

996

12165

520

1062

421

563

860

1838

668

1943

891

1134

9900

0

0

0

0

1626

771

220

453

494

1157

4721

37

116

110

215

680

392

1168

647

291

189

3845

103

141

150

118

213

572

1170

623

407

331

3828

147

315

157

47

445

506

172

326

370

636

3121

5

0

0

0

0

415

119

102

1329

1009

2979

0

0

0

0

207

312

367

1098

274

451

2709

0

0

0

0

32

161

281

282

188

317

1261

0

0

0

0

503

125

23

0

4

2

657

56

17

3

15

138

42

59

82

50

75

537

0

0

0

0

39

45

58

47

40

39

268

0

0

0

0

52

65

43

42

39

26

267

48

42

0

0

31

1

0

0

0

1

123

76

7

1

1

2

0

0

0

0

0

87

0

0

0

0

0

11

3

20

24

18

76

0

0

0

0

6

5

3

11

2

7

34

0

0

0

0

6

4

1

4

3

4

22

0

0

0

0

0

0

11

0

0

5

16

0

0

0

0

4

0

0

0

0

0

4

0

0

0

0

0

0

0

0

0

1

1

1555 — rm — rm — rm — 8i09 idm \\m ism? — ^37^ iisso 77i03

81

Appendix XI. Trawl catch by station

(1976-1985).

JC

NR

NB

IT

BR

IN

Total

Number of samples

1563

1559

1563

1563

1563

1556

9367

Fish Taxa

Pseudopleuronectes americanus

10786

33899

T5760

18697

12923

17025

109090

Stenolomus chrysops

2592

221

15841

5710

3124

9657

37145

Scophthalmus aquosus

1064

1421

1676

2604

9876

2067

18708

Anchoa spp.

718

240

10263

293

15

3261

14790

Raja spp.

689

10

2088

3259

5130

1490

12666

Gadldae

2196

584

4435

1744

326

2084

11369

Menidia spp.

2186

2380

1312

493

152

3205

9728

Taulogolabrus adsperms

1412

297

495

260

377

4108

6949

Myoxocephalus aenaeus

846

2075

329

426

647

1160

5483

Prionotus spp.

72

424

346

905

2144

455

4346

Paralkhthys dentatus

493

588

402

1592

133

419

3627

Merluccius biVmearis

139

3

328

306

1116

465

2357

Urophycis spp.

301

22

212

230

1154

334

2253

Tautoga onitis

442

427

252

177

222

558

2078

Hemilripterus americanus

443

81

403

286

444

398

2055

Microgadus tomcod

638

466

484

71

27

305

1991

Gasterosteus aculeatus

1254

612

8

10

6

8

1898

Pholis gunnellus

851

187

164

98

13

248

1561

Syngnathus fuscus

450

668

103

55

61

132

1469

Peprilus triacanthus

19

3

178

373

730

49

1352

Osmerus mordax

846

227

90

57

36

92

1348

Apeltes quadraais

48

1214

0

1

1

1

1265

Gadus morhua

203

18

244

110

79

291

945

Myoxocfphalus octodecemspinosus

3

0

20

80

505

15

623

EtTopus microstomus

58

4

51

78

263

78

532

Paralkhthys oblongus

0

2

45

6

390

16

459

Ammodytes amerkanus

19

94

4

.28

257

6

408

Atosa pseudoharengus

7

59

16

7

46

233

368

Opsanus tau

5

299

0

0

0

11

315

Centropristis striata

20

35

26

16

22

157

276

Anguilla rostra la

35

146

0

14

2

6

203

Pollachius virens

51

8

7

11

8

118

203

Cyclopterus lumpus

105

4

11

6

2

43

171

IJparis spp.

19

1

32

26

53

24

155

Alosa sapidissima

8

17

50

9

20

22

126

Clupeidae

0

1

0

1

0

111

113

Clupea harengus

63

3

15

4

14

4

103

Cynoscion regalis

18

0

19

8

36

15

96

Sphoeroides maculatus

12

56

9

1

12

6

96

Mustelis canis

4

1

39

3

30

4

81

Alosa aestivalis

1

22

13

6

13

10

65

Brevoortia tyrannus

0

48

12

1

0

3

64

Umanda ferruginea

0

0

0

4

43

0

47

Monacanthus hispidus

IS

1

7

5

10

9

47

Morone americana

6

11

4

1

6

17

45

Macroioarres americanus

0

0

0

1

32

1

34

Gobiidae

2

23

0

0

0

0

25

Fistularia tabacaria

14

1

0

0

0

3

18

82

Appendix XI. (continued)

Fish Taxa JC N^ RT5 TT ^K m T3t3I

Leiostomus xanthurus
Gasterosteidae
Pomalomus saltalrix
Hippocampus spp.
Alutenis schoepfi
Dactylopterus volitans
Synodus foetens
Pungitius pungitius
Fundulus spp.
Priacanthus cruentatus
Menticirrhus saxalilis
Morone saxa tills
Caranx crysos
Lophius americanus
Trinectes maculatus
Ulvaria subblfurcata
Conger oceanlcus
Pristigenys alta
Sphyraena borealis
Trachurus lalhami
Gasterosteus wheatlandi
Lactophrys spp.
Mullus auratus
Ophidian marginatum
Priacanthus arenatus
Selene vomer
Alosa mediocris
Caranx hippos
Chaetodon ocellatus
Decapterus macarellus
Mugit cephalus
Scomber scombrus
Squalus acanthias
Acipenser oxyrhynchus
Auloslomus maculatus
Bairdiella chrysoura
Bothus ocellatus
Dasyatis centroura
Enchelyopus cimbrius
Melanogrammus aeglefinus
Myliobatis freminviUei
Salmo tnitta
Scyliorhinus retifer
Seiar cntmenopihalmus
Selene setapinnis
Trachinocephalus myops
Trachinotus falcatits
Upeneus parvus
Total

2

0

7

0

3

3

15

2

n

13

2

3

2

0

5

1

13

4

3

1

1

0

2

11

5

0

0

1

1

3

10

0

7

0

0

0

2

9

0

3

0

2

4

0

9

5

2

0

0

0

1

8

0

7

0

0

0

0

7

1

0

1

2

0

3

7

0

2

1

2

0

1

6

0

6

0

0

0

0

6

0

0

2

0

1

2

5

0

0

0

I

4

0

5

5

0

0

0

0

0

5

3

0

1

1

0

0

5

1

1

0

0

2

0

4

1

0

0

1

1

1

4

4

0

0

0

0

0

4

1

0

3

0

0

0

4

3

3

2

1

0

0

0

0

3

1

0

0

0

0

2

3

0

0

0

2

1

0

3

0

1

0

0

0

2

3

1

0

1

0

0

1

3

1

0

0

0

1

0

2

0

0

0

0

0

2

2

1

1

0

. 0

0

0

2

1

0

1

0

0

0

2

1

0

1

0

0

0

2

0

0

1

0

0

1

2

0

0

0

0

2

0

2

0

0

1

0

0

0

1

0

0

0

0

0

0

0

0

0

1

0

0

1

0

0

0

0

1

0

0

0

0

0

0

0

0

0

1

0

1

0

0

0

0

0

0

0

1

0

0

0

0

1

0

0

0

0

0

1

0

0

0

0

0

0

0

1

0

0

0

0

1

0

0

0

1

0

0

0

0

0

0

0

0

0

0

1

1

0

0

0

0

0

83

Appendix XI. (continued)

Invertebrate Taxa

-KT

Tnr

"RB"

TT

~mr

Total

Ubinia spp.
Carcinus maenus
Cancer irroratus
Loligo pe.alei
Lunalia heros
Ovalipes oceltatus
liomarus americanus
A rgopeclen irradiana
Pagurus pollicaris
Neopannpe texana
Asterias forbesi
CalUnecles sapidus
Limutus polyphemus
Busycon canaliculatum
Cancer borealls
Cancer spp.
Busycon carica
Polinlces duplicata
Squilla empusa
CalUnecles slmills
Henricia sanguinolenta
Illex illecebrosus
Total

1207

12614

464

12265

1092

1391

1021

140

11

1

416

2565

1294

341

139

2973

155

76

339

848

12

133

97

248

16

210

24

45

30

14

5

2

0

2

2

3

2

■ 0

0

11

0

0

0

0

2486

28

2194

1823

374

46

599

6

351

21

19

110

4

20

43

47

13

5

4

0

0

0

2670

13

5135

1783

1481

424

224

1

424

16

53

12

9

79

14

22

26

2

0

0

2

1_

12390

456

11

1073

2892

2840

382

288

0

1565

4

401

13

1321

20754

27

12808

1280

12165

2241

9900

14

4721

12

3845

1082

3828

2

3121

138

2709

33

1261

39

657

57

537

21

268

50

267

11

123

7

87

13

76

12

34

11

22

5

16

2

4

0

1

84

Appendix XIl. Seine catch by year (1976-1985).

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

Total

Number of samples 66

72

72

72

72

72

80

99

174

156

935

laxa

Menidia spp.

40620

18179

1178

1233

7764

3418

5408

9007

2330

1342

90479

Fundulus spp.

1746

1174

838

660

943

612

914

870

1659

901

10317

Applies quadrants

464

602

254

269

35

109

79

1767

230

107

3916

Cyphnndon varwgatiis

57

672

41

30

10

352

144

47

33

29

1415

Ammodytes amerkanus

6

520

16

51

10

318

82

30

21

0

1054

Pungiliiis piingilius

6

I

11

19

2

3

9

322

10

10

393

Gaslernsleus aculeatus

8

151

8

30

2

3

49

9

4

269

Syngna thus fuscus

9

3

9

108

6

8

21

9

38

27

238

Pomatnmus saltatrix

I

0

1

6

0

2

49

90

19

35

203

A losa pseudnharengus

0

0

0

0

0

0

93

0

94

Gadidae

2

0

9

1

1

24

21

2

18

10

S8

rspudoplmronectes americanus

4

6

4

1

2

9

18

38

85

Mugil cephalus

0

4

3

18

46

1

0

5

0

81

Gasterosteus whnallandi

8

5

5

18

39

Brevoorlia tyrannus

0

0

17

0

4

0

0

8

37

Anguilla rostra ta

11

2

14

4

1

1

0

I

0

35

Myoxocephalus aanaeus

3

2

1

2

0

0

3

3

18

Anrhoa spp.

0

0

0

0

2

0

1

0

12

Mugil nirema

0

0

0

0

0

0

0

9

0

10

Alosa aestivalis

2

6

0

0

0

9

0

0

0

0

8

Ijirania parva

1

2

0

0

0

0

0

2

0

1

6

Tautogolahnis adspersus

0

0

2

0

0

0

3

0

1

0

6

Sphoernides manilatus

0

0

0

1

0

0

1

0

0

3

5

Tautnga nnilis

0

0

0

0

0

0

4

0

0

0

4

Trachinntvs falcatus

0

0

1

0

3

0

0

0

0

0

4

Caranx hippos

0

0

1

0

0

1

0

0

0

I

3

A losa sapidissima

I

0

0

0

0

0

0

0

0

1

2

Clupea harengus

0

0

0

0

0

0

2

0

0

0

2

Men ticirrh us sa xa tills

1

0

1

0

0

0

0

0

0

0

2

Osmerus mordax

0

0

0

0

0

0

0

0

0

2

2

Peprilus triacanthus

0

0

0

0

0

0

1

0

1

0

2

Strongyltira marina

0

0

0

0

0

I

1

0

0

0

2

Ciupcidae

1

0

0

0

0

0

0

0

0

0

Cynoscinn regalis

0

0

0

0

0

0

0

0

0

1

rholis gunnellus

0

0

0

0

0

0

0

0

0

1

Prionotus spp.

n

0

0

0

0

0

0

0

0

I

Srnphthalmus aqunsus

0

0

0

0

0

0

0

0

0

1

Urophycis spp.

0

0

0

0

0

0

0

0

1

0

42943 21324 2409 2433 8831 4870 6771 12207 4505 2544 108837

85

Appendix XIII. Seine catch by station (1976-1985).

JC

WP

GN

Total

Number of itamples

300

314

321

935

Taxa

MRnidia .';pp.
Fundulus spp.
Apeltes quadrants
Cyprinodon variegatus
Ammndylea americanus
Pungitius pungitiu.i
Gasternstms amleatus
Syngnathus /uncus
Pomatomus sallatrix
Atosa pseudnharpngus
Gadidae

rspudopleuronprles ameriranu.'!
Mugit cpphalus
Gaslerosteus wheallandi
Brevoortia tyrannua
Anguilla mslrata
Myoxocephalus annaeu.v
Anchoa spp.
Mugil curema
Alosa anslivalis
Utcania parva
Tautogolabrus adspersus
Sphoernide.'! marulalus
Tauloga onilb
Trachinntiis falralus
Caranx hippos
Alosa sapidissima
Clupea harengus
Meniicirrhus saxalilis
Osmerus mordax
Ppprilus Iriacanlhus
Slrongylura marina
Clupeidnc
Cynoscion rpgalis
Phnlis gunnellus
Prinnotus spp
Scoplitltalnms aquosus
Urophycis spp.

Total

72783

9879

7817

90479

im

1502

1068

10317

3896

6

14

3916

625

767

23

1415

2

197

855

1054

322

67

4

393

227

19

23

269

45

34

159

238

141

7

55

203

5

89

0

94

58

24

6

88

19

7

59

85

55

2

24

81

12

13

14

39

2

6

29

37

32

2

1

35

4

7

7

18

11

1

0

12

10

0

0

10

1

5

2

8

4

0

2

6

5

1

0

6

0

0

5

5

4

0

0

4

2

2

0

4

2

0

1 ,

3

0

0

2

2

2

0

0

2

1

0

1

2

0

0

2

2

0

1

1

2

2

0

0

2

0

1

0

1

0

0

0

0

1

0

1

0

0

0

1

0

1

0

86

Appendix XIV. Time-series models used to describe the log-transformed density {no./500 m) of larval Ammodytes americanus
collected at stations EN and NB and analytical summary.

Station = EN

Model' : Z, = /?|5(l f RiSmitK^) - BjCOSilKs) ' B^SmilKi) + RsCOSitKt)) I Ai + A2

Model summary statistics: SSE ^ 627.5, df = 515, MSE = 1.22, R^ ^ 0.74

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1976

44.2

45

0.98

1977

110.4

44

2.51

1978

160.4

45

3.57

1979

57.0

44

1.30

1980

53.8

44

1.22

1981

69.8

44

1.59

1982

22.9

44

0.52

igg.'?

27.7

44

0.63

1984

,30.2

45

0.67

1985

51.1

44

1. 16

13.4
16.4

Station == NB

Model' : Z, = BiS{\ + B2Sm{lK6) - R^COSilKf) - BiSINitK^) h BsCOSitKi)) + At + A2 + A^ + Af,o

Model summary statistics: SSE = 170.0, df = 355, MSE = 0.48, R^ = 0.92

Year

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1979

17.0

42

0.41

1980

18.3

42

0.44

1981.

31.6

42

0.75

1982

29.3

42

0.70

1983

8.3

42

0.20

1984

16.4

43

0.38

1985

49.2

42

1.17"

19.1
0.2

0.7
19.0

Z, - mean of LOG((no./500 m ) f 1)

/?„ ^ regression coefficients

t - time in days

K^ ~ constant for period of duration m months

Ap ~ autoregressive coefficients at lag p

Mp ^ moving average coefficients at lag p

S " dummy variable for season (see Table 7)

annual component of SSE

MSE " SSE/df

Significanlly higher than the model MSE, F statistic (p

0.05)

87

Appendix XV. Time-series models used to describe the log-transformed catch (no./24 h) or Anchoa spp. impinged at MNPS

Unit 2 and analytical summary.

Model' : Z, - «|F(/2(l - flz-^'M"^!:) ^ B^COSitKn) " BiSINilKs) t RiCOS{tKf,)) - Ay - A2 - A^ -*- Af, + Ai - Ag
iVIodel summary statistics: SSE = 1729.8, df = 510, MSE - 3.39. r' = 0.69

Year

MSE

Sum of deviations from model forecast
Above Below

1976
1977
1978
1979
1980
1981
1982
1983
1984
1985

146.9
82.3
195.0
164:9
122.4
331.5
250.1
259.4

2.20

2.16

3.67

2.06

4.76*

4.12

3.06

8.29*

6.25*

6.49*

1)

Z, = mean of LOG((no./24 h)

/?„ = regression coefficients

t =• time in days

K^ = constant for period of duration m months

Ap ~ autoregressive coefficients at lag p

Wp ~ moving average coefficients at lag p

FV7 ~- water flow through Unit 2

annual component of SSE

MSE = SSE/df

Significantly higher than the model MSE, F statistic (p

34.3
30.3
67.9

0.05)

88

Appendix XVI. Time-series models used to describe the log-transformed density (no./500 m ) of Anchoa spp. eggs collected at

EN and analytical summary.

Model" : Z, = ByS{D2SIN(tKu) " B-iCOS{tKn) + B^SIN{lKf) + BsCOSilK^)) + /ii + Ai+ M7
Model summary statistics: SSE = 279.3, df = 357, MSE = 0.83, R = 0.84

Sum of deviations from model forecast
Year SSe'' df MSE'^ Above Below

19.6 8.1

19.6 9.5

2.5 20.0

1979

25.9

44

0,59

1980

35.3

44

0.80

1981

17.3

44

0.39

1982

26.9

44

0.61

1983

64.1

44

1.46'

1984

77.1

45

1.71-

1985

50.7

44

1.15'

Z, = mean of LOG((no./500 m ) + 1)

/?„ - regression coefficients

t = time in days

Af^ = constant for period of duration m months

A = autoregressive coefficients at lag p

Wp ~ moving average coefficients at lag p

5 - dummy variable for season (see Table 7)

annual component of SSE

MSE - SSE/df

Significantly higher than the model MSE, F statistic (p > 0.05)

89

Appendix XVII. Time-series models used to describe the log-transFormed density (no./500 m' ) of larval Anrhoa spp. collected
at BN and NB and analytical summary.

Station - RN

Model' : Z, - /?,.s(l I B^SINitKf,) + RsCOS{tKs) • BaSINitK^.) BsCOS(tK-i)) ^ /i, )■ A-fj I A/,

Model summary .statistics: SSF, - 336.5, df - 514, MSB - 0.65, r' - 0.93

Year

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1976
1977
1978
1979
1980
1981
1982
1983
1984
1985

18.0
18.6
79.7
22.8
24.9
33.6
27.0
35.5
46.9
29.4

44

0,41

43

0.43

44

1.81

43

0.53

43

0.58

43

0.78

43

0.63

43

0.83

44

1.07

43

Station -^ NR
Model' : Z, - R\S(\ - B2.SllV{lKt) I HjCnSitKi) niSIN{lKj) + BsCOS{lKj))
Model summary statistics: SSE - 269.2, df - 359, MSE = 0.75, R^ - 0.92

Year

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1979
1980
1981
1982
1983
1984
1985

32.2
34.9
55.9
16.2
29.2
59.6
41.2

46

0.70

46

0.76

46

1.21

46

0.35

46

0.64

47

1.27

46

0.89

1)

Z, - mean of I.OG((no,/500 m)

/?„ ~ regression coefficients

t - time in days

K'n, ~ constant for period of duration m months

,-tp autoregressive coefficients at lag p

M ' moving average coefTicients at lag p

5 ~ dummy variable for season (.see Table 7)

annual component of SSE

MSR - SSE/df

Significantly higher than the model MSR, R statistic (p 0.05)

90

Appendix XVIII. lime-series models used to describe the log-transformed catch (no./24 h) of Gastero.'^tmx spp. impinged at
MNPS Unit 2 and analytical summary.

Model' : Z, - RyFU2{\ 4 R2SIN{lK,2) + B}COS{tKn) - RiSIN{lKi) + RiCOSitKi)) -/(, - A2 t- As

Model summary statistics: SSE - 1546.5, df - SI.T, MSF - 3.01, R^ -= 0.82

Sum of deviations from model forecast
Year SSe" df MSE'' Above Below

1976

69.8

44

1.59

1977

64.3

43

1.50

1978

141.7

43

3.30

1979

137.5

43

3,20

1980

120.0

44

2.73

1981

106.1

43

2.47

1982

176.3

43

4.10

1983

106.1

43

2.47

1984

360.8

43

8.39

1985

263.4

43

6.12

58.7
58.2

Z| - mean of LOG((no./24 h) f I)

R„ ~ regression coefficients

t ~ time in days

K^ ~ constant for period of duration m months

A " autoregressive coefficients at lag p

M - moving average coefficients at lag p

FU2 ~ water flow through Unit 2

annual component of SSE

MSE - SSF/df

Significantly higher than the model MSE, F statistic (p

0.05)

91

Appendix XIX. lime-series models used to describe the log-transformed seine catch (no./IOO m) of Menidia spp.
stations GN, JC and WP and analytical summary.

Station - GN

Model' ; Z, - /?|5(l - HiSINUKn) + R^^COSilKn) ^ niSINilKfi) + nsCOS{lRf.))

Model .summary statistics: SSE - 265..-?, df - 194, MSB - 1..37, R^ - 0.88

SSE

df

MSB

Sum of deviations from model forecast
Above Below

1969

13.7

1970

7.6

1971

31.3

1972

28,2

197.^

9.6

1974

26.3

1975

16.3

1976

24.1

1977

6.1

1978

10.3

1979

4.8

1980

9.0

1981

20.4

1982

7.0

198.3

24.1

1984

21.9

1985

4.8

2

6.83

6

1.26

6

5.22

6

4.70

6

1.60

6

4.38

6

2.71

6

4.02

6

1.02

6

1.71

6

0.80

6

1.49

6

3.39

6

1.17

6

4.01

6

3.65

8.4
6.5

12,2
2.9

4.8
5.7

1.6

9.7

3.3

3.8

9 .0

8.3

Station - JC

Model' : Z, - fi,.S(l f R2SIN{lKf,) I R^^COSitKf,))

Model summary statistics; SSE = 150.4, df - 196, MSB - 0.77, r' - 0.83

Year

SSE

df

MSB

Sum of deviations from model forecast
Above nelow

1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985

10.5

12.6
4.1

16.9
8.7

13.3
3.8

13.8
4,6
3.9
8.9
9.3
6.9
9.6

10.0
7.4

4

1.47

8

1.31

8

1.58

8

0.51

8

2.11

8

1.08

8

1.66

8

0.47

8

1.72

8

0.58

8

0.49

8

1.12

8

1.19

8

0.86

8

1.19

8

1.25

8

0.92

92

Appendix XIX. (continued)

Station = WP

Moder : X, = ByS{\ + HiSW^tKyi) \- B-!,COS{tKxi) i B^SmitKf,) - RsCOS{tKf,))

Model summary statistics: SSE ^ 15.6, df ^ 194, MSB = 0.08, r' = 0.81

Sum of deviations from model forecast

Year SSe'' df MSE'^ Above Below

r969 ol ~~

1970 0.7

1971 0.6

1972 1.0
197.3 0..3

1974 1..? 6 0.22* 1.7 0.2

1975 1.6 6 0.26* 1.2 1.1

1976 1.1 6 0.19* 0.2 2.2

1977 0.5

1978 1.0

1979 0.7

1980 0.5

1981 0.9

1982 1.4 6 0.23* 1.7 1.0

1983 1.4 6 0.21* 1.8 0.9

1984 1.1 6 0.18* 1.5 1.5

1985 1.2 6 0.20* 2.3 0.2

Z, - mean of LOG((no./100 m) + 1)

R„ ^ regression coefficients

t ^ time in days

K„ ~ constant for period of duration m months

Ap ~ autoregressive coefficients at lag p

Mp ~ moving average coefficients at lag p

5 ~ dummy variable for season (see Table 7)

annual component of SSE

MSE - SSE/df

Significantly higher than the model MSE, E statistic (p - 0.05)

2

n.23*

6

0.11

6

0.09

6

0.17

6

0.05

6

0.22*

6

0.26*

6

0.19*

6

0.08

6

0.17

6

0.11

6

0.08

6

0.15

6

0.23*

6

0.21*

6

0.18*

6

0.20*

93

Appendix XX. Time-series models used to describe the log-transformed catch (no./24 h) of Menidia spp. impinged at MNPS

Unit 2 and analytical summary.

Model" : Z, = S,Fl/2(l + B^SINilKn) + BjCOSilKn)) ^ A, - A2 + /(u - An
Model summary statistics: SSE = 1349.4, df - 514, MSB = 2.63, r' = 0.75

Sum of deviations from model forecast
Year SSE*' df MSE'' Above Below

1976

82.9

1977

76.7

1978

129.8

1979

102.3

1980

179.5

1981

153.2

1982

133.7

1983

88.8

1984

238.0

1985

164.5

45

1.84

44

1.74

44

2.95

44

2.33

45

3.99

44

3.48

44

3.04

44

2.02

44

5.41

44

3.74

1)

Z^ - mean of LOG((no./24 h)

B„ - regression coefficients

t ~ time in days

K„ ~ constant for period of duration m months

A- ^ autoregressive coefficients at lag p

M„ - moving average coefficients at lag p

FV2 -■ water fiow through Unit 2

annual component of SSE

MSE = SSE/df

Significantly higher than the model MSE, F statistic (p

0.05)

94

Appendix XXI. Time-series models used to describe the log-transformed catch (no./24 h) of Microgadus lomcod impinged at
MNPS Unit 2 and analytical summary.

Model' : Z, = R^FU2{\ + B2SIN(tK\-i) + B:iCOS(tKi2) - BiSIN(tK(,) + BiCOS(tKf,)) - /f, - A^

Model summary statistics: SSE = 1538.0, df = 514, MSE = 2.99, R^ = 0.69

Sum of deviations from model forecast
Year SSE df MSE*^ Above Below

48.9 28.7

49.7 34.9

1976

34.6

45

0.77

1977

64.9

44

1.48

1978

107.8

44

2.45

1979

208.8

44

4,75"

1980

91.0

45

2.02

198)

196.0

44

4.45'

1982

196.6

44

4.47'

1983

103.5

44

2.35

1984

351.4

44

7.99'

1985

182.9

44

4.16'

Z, == mean

of LOG((no./24 h) + I)

B_ - regrei

ssion coefficients

62.2 56.1

23.3 52.3

t = time In days

K^ = constant for period of duration m months

/Ip ~ autoregressive coefficients at lag p

M„ ~ moving average coefficients at lag p

FU2 ~ water flow through Unit 2

annual component of SSE

MSE -= SSE/df

Significantly higher than the model MSE, F statistic (p > 0.05)

95

Appendix XXII. Time-series models used to describe the iog-transformed catch (no./24 h) of Myoxncephalua aenaeus impinged
at MNPS Unit 2 and analytical summary.

Model' : Z, = B|F(72(l + /?2.S//V(fA'|2) -I- R^COS{tKu)) - Ai - A2

Model summary statistics: SSE = 1804.6, df = 516, MSB = 3.50, R^ = 0.83

Sum of deviations from model forecast
Year SSe'' df MSE^ Above Below

1976

124.7

47

2.65

1977

110.2

46

2.40

1978

151.8

46

3.30

1979

170.5

46

3.68

1980

139.1

47

2.96

1981

126.3

46

2.75

1982

142.0

46

3.09

1983

189.2

46

4.11

1984

305.7

46

6.65

1985

345.7

46

7.51

7.^ = mean of LOG((no./24 h) + 1)

B„ ~ regression coefficients

t =^ time in days

K^ - constant for period of duration m months

A„ ^ autoregressive coefficients at lag p

M„ ~ moving average coefficients at lag p

FV2 - water flow through Unit 2

annual component of SSE

MSB = SSB/df

Significantly higher than the model MSB, F statistic (p

0.05)

96

Appendix XXHI. Time-series models used to describe the log-transformed density (no./500 m ) of larval Myoxocephalus
aenaeus collected at stations EN and NB and analytical summary.

Station = FN

Model' : Z, = BiSiBiSINilKn) + RiCOS{lKi2) - BiSIN{tKi) - BsCOS{tK^)) + A\ - As - Mi " Mf,

Model summary statistics: SSE = 111.4, df = 514, MSB = 0.22, R^ = 0.93

Sum of deviations from model forecast
Year SSE*" df MSE*^ Above Below

1976

13.1

44

0.30

1977

15.4

43

0.36

1978

7.5

44

0.17

1979

3.6

43

0.08

1980

5.7

43

0.13

1981

19.2

43

0.45

1982

10.0

43

0.23

1983

19.9

43

0.46

1984

9.6

44

0.22

1985

7.3

43

0.17

0.5
4.6

9.4

12.3

15.2
10.7

5.2
4.4

Station ^ NB
Model' : Z, = BxSl^B^SINitK^i) + BsCOS(tKn) - BtSIN(tKi) + BiCOS(tKi))
Model summary statistics: SSE = 62.1, df = 360, MSB = 0.17, R^ = 0.93

SSE

df

MSB

Sum of deviations from model forecast
Above Below

1979

8.1

47

0.17

1980

5.8

47

0.12

1981

10.5

47

0.22

1982

3.6

47

0.07

1983

12.1

47

0.26

1984

10.7

48

0.22

1985

11.4

47

0.24

5.8

4.5

Z^ - mean of LOG((no./500 m ) + 1)

/?„ = regression coefTicients

t ~ time in days

K^ - constant for period of duration m months

/fp ~ autoregressive coefTicients at lag p

Wp moving average coefficients at lag p

5 - dummy variable for season (see Table 7)

annual component of SSE

MSB - SSB/df

Significantly higher than the model MSB, F statistic (p

0.05)

97

Appendix XXIV. Time-series models used to describe the log-transformed density (no./500 m ) of Tauloga nnitis eggs collected
at station EN and analytical summary.

Model' : Z, =- n^s{- ttiSINitKn) - R^COS(tK\2) ^ RiSIN(tKf,) i FsCOS{lK()) + A^ + Wj

Model summary statistics: SSR - 163.8, df - 3SR, MSP, - 0.46, R^ - 0.97

Sum of deviations from model forecast
Year SSE*" df MSE'' Above Below

1979

14.2

45

0.32

1980

20.9

45

0.46

1981

38.6

45

0.86

1982

19.0

45

0.42

1983

10.9

45

0.24

1984

35.5

46

0.77

1985

24.7

45

0.55

Zi - mean of LOG((no./-500 m) + I)

/?„ ~ regression coefficients

t - time in days

K^ -- constant for period of duration m months

/) ~ autoregressive coefficients at lag p

W ~ moving average coefTicients at lag p

S ~ dummy variable for season (see Table 7)

annual component of SSB

MSE - SSE/df

Significantly higher than the model MSE, F statistic (p ^- 0.05)

98

Appendix XXV. Time-series models used to describe the log-transformed density (no./500 m) of larval Tauloga onith collected
at stations EN and NB and analytical summary.

Station = EN

Model' : Z, = n^si" B2SIN(tKn) - B}COS{tKa) - B^SINilKt) -BsCOS{lKt) + B6SlN{lK2) + njCOSilKi)) + A,

Model summary statistics: SSE = 151.3, df = 515, MSE = 0.29, R^ -= 0.7!

Year

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1976

14.0

45

0.32

1977

8.2

44

0.19

1978

27.1

45

0.60

1979

6.7

44

0.15

1980

14.6

44

0.33

1981

28.1

44

0.64

1982

12.1

44

0.28

1983

14.5

44

0.33

1984

19.0

45

0.42

1985

7.0

44

0.16

13.5

Station - NB

Model' : Z, = Bi5( - Bi^'f^C^n) ' fljCOSff AT,,) - BiSlNilK^) - BsCOS{tKi) + BiSII^itKi) ^ B^COS{lK2))

Model summary statistics: SSE = 138.5, df - 358, MSE = 0.39, r' = 0.85

Year

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1979

17.6

45

0.39

1980

13.9

45

0.31

1981

25.8

45

0.57

1982

13.7

45

0.30

1983

23.0

45

0.51

1984

24.8

46

0.54

1985

19.7

45

0.44

7'i '

mean

of I

OG((no./500 m') 1-

1)

»n ="

regression

coefficients

t ~ time in days

K^ ~ constant for period of duration m months

/1p - autoregressive coefficients at lag p

M " moving average coefficients at lag p

5 "-" dummy variable for season (see Table 7)

annual component of SSE

MSP, - SSE/df

Significantly higher than the model MSE, F statistic (p

0.05)

99

Appendix XXVI. Time-series models used to describe the log-transformed density (no./SOO m ) of Tautognlabrus adsperaus eggs
collected at station EN and analytical summary.

Model' : Z, = B\S{BiSIN{tKx2) - BjCOSitKn) ^ BiSIN{tK<i) - BsCOS{lKt)) + A^ - /),

Model summary statistics: SSE = 227.6, df -- 358. MSB ^ 0.64, R ^ 0.96

Sum of deviations from model forecast
Year SSE*" df MSE*" Above Below

1979

15.0

45

0.33

1980

15.6

45

0.35

1981

44.9

45

1.00

1982

31.5

45

0.70

1983

39,1

45

0.87

1984

44.9

46

0.98

1985

36.6

45

0.81

Z, = mean

of

LOG((no./500 m') +

1)

B. = regre

-sio

n coefTicients

t = time in days

K^ ~ constant for period of duration m months

Ap ~ autoregressive coefTicients at lag p

Mp ~ moving average coefTicients at lag p

S -= dummy variable for season (see Table 7)

annual component of SSE

MSE - SSE/df

SigniTicantly higher than the model MSE, F statistic (p

0.05)

100

Appendix XXV II. Time-series models used to describe the log-transformed density (no./SOO m ) of larval Tautogolabrus
adspersus collected at stations EN and NB and analytical summary.

Station = EN

Model :

Z, - /?,,S( - B2SIN{lKi2) - niCOSilKu) " BiSl/VilKf) - BsCOS{tKi) + BtSINitK^) + BiCOS(tK2)) + A^ I- A^ - A-i + A^

Model summary statistics: SSE = 152.5, df = 511, MSE = 0.30, R^ - 0.72

Year

SSE

df

MSE

Sum of deviations from model forecast
Above Below

1976

3.6

41

0.09

1977

15.1

40

0.38

1978

25.8

41

0.63

1979

5.5

40

0.14

1980

22.7

40

0.57

198!

26.7

40

0.67

1982

8.9

40

0.22

1983

15. 1

40

0.38

1984

17.2

• 41

n.42

1985

12.0

40

0.30

1.1

4.7

Station - NB
Model' : Z, = BiS{ - B2SIN(tKi2) - B3COS{lKt2) " B^SmilKt) - BsCOS{tKi))
Model summary statistics: SSE = 142.3, df = 360, MSE = 0.40, R^ = 0.85

SSE

df

MSE

Suiji of deviations from model forecast
Above Below

1979

11.7

47

0.25

1980

16.9

47

0.36

1981

28.3

47

0.60

1982

19.6

47

0.42

1983

24.0

47

0.51

1984

26.1

48

0.54<

1985

15.8

47

0.34

Z, ~ mean

of l,OG((no./500 m') +

1)

/?. ^ regre

"sion coefficients

t - time in days

K^ constant for period of duration m months

/(p =" auloregressive coefficients at lag p

M„ ~ moving average coefficients at lag p

5 - dummy variable for season (see Table 7)

annual component of SSE

MSE - SSE/df

Significantly higher than the model MSE, F statistic (p

0.05)

101

Appendix XXVIII. Time-series models used to describe Ihe log-lransformed catch (no./24 h) of Tautngntahrus adspprsus im-
pinged at MNPS Unit 2 and analytical summary.

Model' : Z, = /?iFt/2(l - B2SIN(tKn) - BT,COS(lKn)) - /(| - A^ - As

Model summary statistics: SSE = 1819.4, df - 515, MSB - ,3.53, R^ - 0,67

Sum of deviations from model forecast
Year SSe" df MSE*^ Above Below

1976

ion.7

46

2.19

1977

129.5

45

2.88

1978

174.2

45

3.87

1979

114.1

45

2.54

1980

133.8

46

2.91

1981

133.0

45

2.96

1982

153.2

45

3.41

1983

168.9

45

3.75

1984

446.6

45

9.92*

1985

264.9

45

5.89*

Z( - mean

of LOG({no./24 h) 1- 1

)

/?„ = regre;

ssion

coefficients

56.9 80.0

36.3 66.9

I ~ time in days

K^ - constant for period of duration m months

A - auloregressive coefficients at lag p

M„ - moving average coefficients at lag p

FU7 ~= water flow through Unit 2

annual component of SSE

MSE - SSE/df

Significantly higher than the model MSE, F statistic (p > 0.05)

102

Contents

WINTER FLOUNDER STUDIES 1

INTRODUCTION 1

MATERIALS AND METHODS 3

Adult abundance studies 3

Life history studies 8

Movements and exploitation 13

Stock identification 13

Larval studies 14

Post-larval studies 23

Growth and mortality 25

Impingement 26

Entrainment 26

Impact assessment 27

RESULTS AND DISCUSSION 28

Adult abundance studies 28

Abundance in the Niantic River 28

Harmonic regression models 35

Regional trends in abundance 36

l,ife history studies 37

Reproduction 37

Age and growth 42

Mortality and survival 49

Food habits 51

Movements and exploitation 53

Stock identiiication 58

larval studies 60

Net extrusion studies 60

Diel behavior 61

24-h studies 64

Abundance and distribution 68

Age and growth 79

Tidal export and import 87

Post-larval stage 91

Abundance (age 0) 91

Growth and mortality (age 0) . . ; 91

Abundance (age 1) 99

Impingement 102

Abundance 102

length and sex distribution 105

Fish return sluiceways 106

Entrainment . . ". 1 09

Abundance 109

Survival 113

Impact assessment 115

CONCLUSIONS 117

SUMMARY 118

REFERENCES CITED 123

APPENDICES 139

WINTER FLOUNDER STUDIES
INTRODUCTION

The purpose of this report is to summarize research completed by Northeast Utilities Environmental
Laboratory (NUEL) and various consultants on the winter flounder {Pseudopleuronectes americanus) prior
to 3-unit operation of MiUstone Nuclear Power Station (MNPS). Due to its local abundance, this species
has been studied intensively since 1973 and considerable data have been collected on its life history,
population dynamics, and impact assessment. The large effort devoted to winter flounder studies is related
to its importance for the Coimecticut sport and commercial fisheries. It is the most valuable commercial
finfish in Connecticut and on average makes up about lOVa of the total fmfish landings. The winter
flounder is also one of the most popular marine sport fishes in the state with an estimated aimual catch
iu 1979 of almost 1.4 million fish weighing 412,234 kg (Sampson 1981; Blake and Smith 1984). Its
particular life history also makes it potentially susceptible to various types of localized impacts.

The winter flounder ranges from Labrador to Georgia (Leim and Scott 1966) and is one of the most
common demersal fishes in inshore waters along the northeastem coast from Nova Scotia to New Jersey
(Perhnutter 1947). The population of winter flounder is composed of reproductively isolated stocks which
spawn in specific estuaries and coastal areas (Lobell 1939; Perlmutter 1947; Saila 1961). Most adult winter
flounder enter natal estuaries in fall and early winter and spawning occurs in late winter and early spring.
Females usually mature at age 3 and 4 and males at age 2. Average fecundity is about 500,000 eggs per
female with as many as 2.3 mUlion eggs for a 45-cm fish. Winter flounder eggs are demersal and hatch
in about 15 d, depending upon water temperature. Small larvae are planktonic and remain in natal estuaries
to a great extent, although some may be carried out into open waters by tidal currents. Some of these
larvae may return to the estuary on subsequent incoming tides, but the rest are lost from the system. The
larval stage lasts about 2 mo, depending upon water temperature. Larger larvae maintain some control
over their position by vertical movements and also may spend considerable time on the bottom. Following
metamorphosis, most demersal juveniles remain in the estuary in shallow waters. Juveniles are resistant
to warm summer water temperatures found there to at least 30.4 °C (Huntsman and Sparks 1924).
Immature yearling winter flounder become photonegative and though many remain within the estuary, are
usually found in deeper water than young-of-the-year (Pearcy 1962; McCracken 1963). Many adults stay

in estuaries following spawning, while others disperse into deeper waters. By summer, most have left
shallow waters as their preferred temperature range is 12-15 °C (McCracken 1963). However, some remain
inshore and may escape temperatures above 22.5 °C by burying themselves in cooler bottom sediments
(OUa et al. 1969). Adults are omnivores and as opportunistic feeders eat a wide variety of algae and
benthic invertebrates. They are sight feeders and are usually active only during the day. Additional details
regarding their life history, physiology, behavior, and population dynamics may be found in Klein-MacPhee
(1978).

Because winter flounder stocks are localized, NUEL studies have concentrated on the dynamics of
the population spawning in the Niantic River to determine if MNPS impacts of impingement and entrain-
ment have caused or would cause changes in local abundance beyond those expected from natural variation.
Preliminary field studies to estimate abundance of this population in 1973-74 were expanded in scope in
1975, when surveys using mark and recapture techniques were initiated. An adult abundance survey has
been completed each year through the present. In many years, studies of age structure, reproductive
activity, growth, survival, movements, early life history, and stock identification have been conducted. For
plant impact, impingement and entrainment estimates are available for each year. Data from many of
these studies have been used in a predictive mathematical population dynamics model developed by the
University of Rhode Island (Saila 1976). This model has formed the basis for all MNPS impact assessments
to date, including that for Unit 3 (NUSCo 1983c). However, a stochastic population dynamics model is
under development which should more realistically predict population-level effects over the expected
duration of MNPS operations. Increased knowledge of larval population dynamics and the stock-recniitment
relationship is necessary for the successful application of this model and has been the focus of recent efforts
at NUE1-.

Tliis report includes a summarization of the data, results, and conclusions for various winter flounder
studies from 1973 through the winter 1986 adult abundance survey. Unit 3 began startup tests in fall 1985
and commenced commercial operations in late April of 1986. Therefore, no data from sampling programs
(other than the adult survey) after fall 1985 will be presented in this report. These data are from the
operational period for Unit 3 and will be included in future reports. Additional information on sampling
methodologies, program evaluations, and detailed results and analyses may be found in previous annual
reports and documents, including NUSCo (1975, 1976, 1977, 1978a, 1978b, 1979, 1980, 1981a, 1981b,
1982, 1983a, 1983b, 1983c, 1984, 1985, 1986a, 1986b).

MATERIALS AND METHODS

Adult abundance studies

Abundance estimation of the Niantic River population of adult winter flounder has been based on
mark and recapture methodologies and details concerning annual surveys from 1973 through 1986 are
summarized on Table 1. Fish tagging began in 1973 and 1974, but Niantic River spawners were not
specifically targeted; the numbers marked were inadequate for abundance estimation (see NUSCo 1975 for
additional details). The 1975 survey design was based on the requirements of the deterministic triple-catch
model (Ricker 1958). Fish captured by trawl in various portions of the river were marked by fm clips
over a 7-wk period beginning on March 31; recaptures were not remarked (NUSCo 1976). From 1976
through 1981, surveys commenced in early to mid-March and ended during early to mid- May, after all
spawning was completed (NUSCo 1977, 1978a, 1979, 1980, 1981a, 1982). Since 1982, each survey started
after ice-out in the river from mid to late February and ended in early April, when the proportion of
reproductively active females decreased to less than 10% of all females examined for two consecutive weeks
(NUSCo 1983a, 1984, 1985, 1986a). In all years since 1975, sampling took place on 2 to 3 d of each week.

In 1976, the Niantic River was subdivided into a number of areas (stations) for each survey (Fig. 1).
Stations 1, 2, and 4 were in the navigational chatmel of the lower to mid-river and 3, 6, 7, and 8 were in
the adjacent shallows. After 1979, no tows were made outside of the navigational channel in the lower
portion of the river due to an agreement with the East Lyme-Waterford Shellfish Commission to protect
bay scallop (Argopeclin irradiam) habitat. In 1983, station 5 in the upper river was subdivided into
stations 51-53; station 54 in the upper arm was not established until 1986 (Fig. 2). Some tows in station
51 during 1984-86 along the eastern shore of the upper river extended into the deeper northern portion of
former station 6. Tows each week were usually allocated to stations according to station area and the
expected abundance of winter flounder; more tows were made where fish were most numerous. In most
years, heavy accumulations of macroalgae and detritus that occurred in the deeper portion of station 51
hindered sampling there.

Table 1.

Summary of Niantic
1986.

River adult winter flounder abundance studies from 1973 through

Dales Marking

sampled method

1973 Throughout Anchor lag

year

1974 Throughout Anchor tag

year

1975 Mar31-Mayl3 Fin clip

1976 Mar 1-May4 Fin clip,

spaghetti lag

1977 Mar 7-May 10 Freeze-brand

Mar 6-May 16 Freeze-brand

Mar 12- May 15 Freeze-brand

Mar 1 7-May 6 Freeze-brand

Mar 2-May 3 Freeze-brand

reb22-Mayll Freeze-brand

r-cb 2 1 -Apr 6 Freeze-brand

Size
marked

Method of
abundance
estimation

None Only 1000 marked in Niantic River

inadequate Tor abundance estimate

Jolly (1965) Only 2300 marked in Niantic River.
Recaptures not marked.

Triple-catch Designed for triple-catch model. Recaptures
(Ricker 1958), not marked - inadequate for Jolly model
Jolly (1965)

Jolly (1965) Designed for Jolly model (1976-86).

Recaptures in 1976 marked with tags.

Jolly (1965) Freeze-brand used to improve marking

methodology. Marks indicating both station
and week of mark and recapture applied
during 1977-79.

Jolly (1965)

Jolly (1965) Jolly model evaluated.

Jolly (1965), Other mark and recapture models considered.

Manley-Parr and Marks indicating week of mark and recapture

Fisher-Ford applied during 1980-86.
(Begon 1979)

Jolly (1965)

Jolly (1965) All winter flounder studies evaluated.

Jolly (1965) Minimum size increa.sed so mostly adults

marked. Survey limited to spawning season.
Tow distance standardized. All marked fish
sexed and measured.

Feb 14- Apr 4 Freeze-brand
[•eb 23-Apr 2 Freeze-brand
Feb 24-Apr 8 Freeze-brand

Jolly (1965)

Jolly (1965) Jolly model evaluated.

Jolly (1965)

Niantic
River

Figure 1. I^ocation of Niantic River adult winter flounder sampling stations from 1976 through 1982.

Niantic
River

Figure 2. Location of Niantic River adult and juvenile winter flounder sampling stations from 1983 through 1986.

Winter flounder were captured with a 9.1-ni otter trawl (6.4-mm bar mesh codend liner) towed by
various vessels. From 1983 through 1986, tow was standardized at 0.55 km. This distance was chosen
because it represented the maximum tow length at station 1 and because using the same tow length at all

stations was expected to reduce variability in calculating catch-per-unit-effort (CPUE), used as an index
of abundance. However, because catch data from station 2 were also used for the trawl monitoring
program, these hauls were maintained at a tow distance of 0.69 km. Prior to 1983, tows were not
standardized. Mostly because of differences in tidal currents, wind, and amounts of extraneous material
collected in the trawl, tow times for the standardized disttmces varied and were usually greater in the lower
than in the upper river. For 1976-86, the mean duration for tows at stations 1 and 2 was 14.4 min and
at stations 4, 51, 52, and 53 was 12.1 min. Tows from 1976-82 that had extremely short or long durations
compared to the distribution of tow times from 1983-86, when tow distance was uniform, were excluded
from data analyses and calculation of CPUE. For comparisons among years, all catches of winter flounder
larger than 15 cm made during a 4-wk period from mid- March through early April were standardized to
either 15-min tows (stations 1 and 2) or 12-min tows (all other stations). The annual mean and median
CPUE were determined and a 95% confidence interval was calculated for each median using a distribution-
free method (Snedecor and Cochran 1967). The catch of winter flounder taken in the trawl monitoring
program from October 1976 through September 1985 (see Fish Ecology section for methods) was also
used to calculate median CPUE values as indices of abundance for various size groups.

The winter flounder caught in each tow during the adult abundance survey in the Niantic River were
briefly held in water-filled containers. At least 200 randomly selected fish were measured to the nearest
0.1 cm in total length during each week of the population abundance survey in all years. During 1983-86,
all winter flounder larger than 20 cm were measured and sexed. Non-measured fish were classified into
various length and sex groupings, depending upon the year; at minimum all fish caught can be classified
as smaller or larger than 15 cm. Since 1977, the sex and reproductive condition of the larger winter
flounder were determined either by observing eggs or milt or by the presence (males) or absence (females)
of ctenii on the caudal peduncle scales of the left side (Smigielski 1975). Following measurement or
classification, all fish 15 (1977-82) or 20 (1983-86) cm or larger were marked with a number or letter made
by a brass brand cooled in liquid nitrogen; the mark was changed weekly. Fish recaptured were noted
and remarked with the brand designating the week of their recapture. In 1976, fish were fin clipped in
various ways and recaptures were marked with a numbered spaghetti tag.

Estimates of abundance of all winter flounder 1 5 or 20 cm and larger in the Niantic River during the
spawning season were obtained from the mark and recapture data using the Jolly (1965) model. The
actual computations were done using a computer program (Davies 1971) of Jolly's model with minor

modifications as described in NUSCo (1982). Prior to 1985, absolute estimates of winter flounder abun-
dance during the spawning period had been obtained by starting with an estimate of N obtained during
the first week of the survey and then adding the total number of fish joining (Jolly's B) during subsequent
weeks. As a result of a comprehensive review of the mark-recapture methodology in 1985 (NUSCo 1986a),
this procedure was eliminated. In its place a composite index was developed for describing the relative
abundance of adult winter flounder. This index was computed by avera^g the weekly estimates of N
made during the winter flounder spawning season, except for the first and last estimates. These estimates
are less reliable and were eliminated from the computations in all years except when the number of values
used would have been less than three. The standard error of N was determined as:

(j)7Var o{{Nj) + Var of(yV3) + Var of(yV4) (1)

where N is the estimate of population size during each week

Fluctuations in the log-transformed catches of winter flounder taken at all six stations of the trawl
monitoring program (see Fish Ecology section) were analyzed using harmonic regression techniques,
methods of which were most recently described in NUSCo (1986a). Catch data from three replicated tows
taken every other week were averaged to obtain a single biweekly mean. These values were used to
construct various models describing catches from October 1976 through September 1985.

Life history studies

Various life history data have been collected since 1973 (Table 2). General methods and procedures
for most studies briefly follow. For additional details concerning particular studies, specific reports should
be consulted.

Reproduction

Using data from 1981-86, probit analysis (SAS Institute Inc. 1985) was used to estimate the length at
which 50% of all females were mature. An index of the number of females reproducing in the Niantic
River each year since 1977 was created by estimating their abundance in each 1-cm length increment
starting with 26 cm. Fecundity (annual egg production per female) of Niantic River winter flounder was

Table 2. Summary of Niantic River adult winter flounder life history information collected

from 1973 through 1986.

Year

Types of studies

Comments

1973 I.englh frequency, food habits, movements and exploitation.

1974 Length frequency, food hahits, movements and exploitation.

1975 Lengjh frequency

1976 Length frequency, sex ratio

1977 Aging, length frequency, fecundity, length-weight, sex ratio and
maturity

Anchor tag returns used for movements and exploitation study

Not all adults measured from 197.5 through 1983
Not all adults sexed from 1976 through 1983

Both scale and otolith samples examined for age during 1977
and 1978

Aging, length frequency, length-weight, sex ratio and
maturity

1979 Aging, length frequency, sex ratio and maturity, survival

Only scales used for aging from 1979 through 1983

1980 Aging, length frequency, sex ratio and maturity, survival, stock

identification

Stock identification from isoelectric focusing of eye lens
proteins by URI during 1980 and lORl

1981

Aging, length frequency, sex ratio and maturity, survival, stock
identification, movements and exploitation

Petersen disc tag returns used for movements and
exploitation studies from 1981 through 1983

Aging, length frequency, sex ratio and maturity, survival,
movements and exploitation

Life history studies evaluated

Aging, length frequency, sex ratio and maturity, survival,
movements and exploitation

All adults measured and sexed from 1983 through 1986. The
von Bertalanffy growth model applied to data.

1984

Length frequency, sex ratio and maturity, movements and
exploitation

Adult life history studies decreased in favor of increased
larval and juvenile work.

1985 Length frequency, sex ratio and maturity

1986 I ength frequency, .sex ratio and maturity

estimated from length -frequencies and a length-fecundity relationship determined from 1977 data using a
functional regression model with log-transformed vaxiables (Jolicoeur 1975; Sprent and Dolby 1980).
Forty-eight fish from 24.5 to 43.3 cm were examined according to methods found in NUSCo (1978a).

Data from an unpublished independent assessment of fecundity, which used 65 fish (19.7-45.3 cm) taken
in Niantic Bay and at MNPS in 1977, were also used in a functional regression for comparative purposes.
Annual mean fecundity was determined from the sum of all individual fecundities divided by the number
of spawning females. The sum of the fecundities gave a relative annual index of egg production.

Age and growth

Separate length-weight relationships for Niantic River (270 specimens; 4.5-43.3 cm) and Bay (491;
6.7-45.3 cm) winter flounder were described with a functional regression with log-transformed variables.
Specimens collected in 1977 and 1978 were measured to the nearest 0.1 cm in length and the nearest 0.1
g in weight.

During 1977-1982, randomly selected specimens were aged by examination of scales removed from
the right side between the dorsal fm and the lateral line. Five or more scales from each specimen were
cleaned and mounted in plastic resin on a slide and examined using a Bausch and Lomb trisimplex
projector or a compound microscope. Except for the first year of life, winter flounder have a zone of
widely-spaced circuli (fast spring and summer growth) followed by a zone of closely-spaced circuli (slow
fall and winter growth). The outer edge of the closely- spaced circuli was considered to be an annulus
(Lux and Ntchy 1969; Lux 1973). Age of each specimen was determined by at least two people. Some
comparisons of age were made during 1977-78 using otoliths with methods described in Williams and
Bedford (1974) and Kurtz (1975). Annual age-length keys were constructed by determining the percentage
that each of the ages made up of every 1-cm length increment in the sample of aged fish. This key was
used to assign an age to all fish measured during the abundance surveys.

The growth rate of Niantic River winter flounder was determined by additional examination of one
of the scales used in age determination in 1983. Based on previous findings, a stratified sample (Ketchen
1950; Ricker 1975) was used to select fish for aging. From five to ten scale samples were allocated to
each 1-cm size interval of both sexes starting with 20 cm; scales from a number of smaller fish were also
selected. Measurements were taken from the midpoint of the scale focus to each annulus and to the
anterior margin of the projected scale image along a standard axis (Tesch 1968; Everhart et al. 1975). For
the back-calculation of length-at-age, the relationship between scale size and fish length was examined.
Some curvilinearity was seen in this relationship, especially for larger specimens, indicating probable

10

heterogeneous growth of the scale and fish (NUSCo 1984). Therefore, length at each annulus was
calculated for each sex by the non-linear relationships:

length = 3.557( scale sizef'^"^ for females, (n = 216, r^ = 0.93) (2)

length = 3.777( scale size)"'^"'* for males, (« = 193, r^ = 0.94) (3)

Annuli measurements for each fish were substituted into the appropriate regression equation for back-
calculation of growth. Mean lengths-at-age with 95% confidence intervals were then computed.

Using the 1983 length-at-age data, the von Bertalanffy growth model (Ricker 1975; Gallucci and
Quinn 1979) was used to describe the growth of Niantic River winter flounder:

L, = L«,(l-et-^{'-'»'!) (4) .

where L/ = length in mm at time t
K = growth coefficient
Loo = asymptotic maximum length
?o = hypothetical date at which a fish would
have zero length if it had always grown
in the manner described by the equation

A nonlinear procedure using the modified Gauss-Newton iterative method (SAS Institute Inc. 1985) was
used to estimate the growth model parameters from the length-at-age data. The co parameter (the product
of Loo and K) of Gallucci and Quirm (1979) was calculated for comparisons of growth.

Similarly, the growth model was applied to the entire 1977-83 age-length data set. As all age 1 and
2 and some age 3 fish were not sexed, these specimens were used with both females (through age 10) and
males (age 8). An independent assessment of growth was made using lengths at marking and recapture
of 129 females and 81 males tagged with Petersen discs (see Movements and Exploitation below). As
recommended by Sundberg (1984), the method of Fabens (1965) was used with these data to estimate Loo
and K. Most recaptures used in the analysis were from NUSCo sampling to ensure that length data were

11

accurate. A few commercial returns and those from the Connecticut Department of Environmental
Protection (CT DEP) and research institutions were also included. The data were constrained to include
only fish captured after at least 90 d at large that showed positive growth; negative or zero grovrth was
assumed to be due to measurement error or to severe effects of tagging which retarded growth.

Mortality and survival

Two methods were used to estimate survival (S) and the instantaneous mortality coefficient Z ( = -In
S). The annual age-length keys from 1978-79 and 1981-83 were used with the length-frequency distributions
of all measured fish 15 cm and greater (0.5-cm groupings) to determine total number by age. Catch curves
were constructed and the slope of the natural logarithm of number plotted against age was used as an
estimate of Z (Ricker 1975). Estimates of survival were also made using the method of Robson and
Chapman (Robson and Chapman 1961; Ricker 1975):

S = ^^ (5)

where T = yVi + 2N2+ 3N3 + ...
Y,N=No+ Ni+ N2 +..

A^o ~ number of age 3 winter flounder
A'l = number of age 4 winter flounder

variance = S

Food habits

The food items of 306 winter flounder collected in the area of Millstone Point from June 1973 through
November 1974 were examined. Whole stomachs were removed and preserved in 10% buffered formalin.
Each stomach was cut open, examined, and subjectively ranked according to fullness, and assigned point
values (Hynes 1950) as follows:

100 - full; appeared unable to hold any additional ingested material

12

75 - three-quarters full; stomach distended such that no folds seen
50 - half-full; partial stomach distention

25 - one-quarter full; some ingested material, but little distention
0 - empty; no ingested material

TTie stomach contents were sorted and classified to a major taxonomic grouping. A visual estimate was
made of the percentage of stomach contents for each taxon. The fullness point total for each stomach
was multiplied by the percentage of each taxon to give a point value for each food item and averages were
computed for each station.

Movements and exploitation

During February through July of 1973 and 1974, approximately 2,000 and 2,600 winter flounder,
respectively, were individually marked with a Floy anchor tag and released in various areas near Millstone
Point. The tagging study was performed by a consultant and initial tagging data are not available which
limits the usefulness of the study. However, tag returns that were reported in NUSCo (1975) may be
used to make inferences concerning movements and exploitation by the sport and commercial fisheries.

From December 1980 through September 1983, almost 5,000 specimens larger than 20 cm were
marked with a Petersen disc tag. During tagging operations, length and sex information were recorded
along with location and date of release. A white 1.3-cm diameter disc uniquely numbered and printed
with information for its return was positioned on the nape of the right side of the fish and a red disc with
additional information was used on the left side. A nickel pin was pushed through the musculature, cut
to size, and its end was crimped over to connect the tags and hold them in place. Except for specimens
released specifically at the MNPS intakes, winter flounder were returned to the location of their capture.
Information requested at recapture included date, location, method of capture, length, sex, and additional
scales. A reward of $1.00 was given to all persons returning a tag.

Stock identification

A special study was undertaken for NU by the University of Rhode Island to determine if local
populations of winter flounder could be distinguished using a biochemical technique, direct tissue isoelectric

13

focusing. Theory and details regarding this electrophoretic method may be fround in the original report
(Schenck and Saila 1982) as well as in Lundstrom (1977), Saravis and Zameheck (1979), and Marine
Colloids (1980). Samples were taken during the spawning season when stock separation should have been
greatest. From February through April 1980, approximately 50 winter flounder were collected from New
Haven, CT; Connecticut River; Niantic River, Niantic Bay, and Jordan Cove (combined for analysis);
Thames River, CT; Mystic River, CT; and Charlestown Pond, RI. In March 1981, about 75 fish were
examined from the Cormecticut River, Niantic River, Niantic Bay, Jordan Cove, and Thames River.
Additional samples were collected in Niantic Bay during each season to examine changes on an annual
basis. All except the New Haven fish were processed immediately after collection. Each fish was pithed,
measured, weighed, sexed and its eye lenses were removed and individually frozen. After the eye lens
proteins were separated, sample gels for each specimen with separated protein bands were fixed and stained
and examined for the presence or absence of certain protein bands. Some samples were quantitatively
read with a scanning densitometer. Data were analyzed using linear discriminant analysis, details of which
may be found in Schenck and Saila (1982).

Larval studies

Abundance and distribution

Ichthyoplankton collections containing larval winter flounder have been made at numerous locations
in the Millstone area since 1973. Prior to 1979, the collection of winter flounder was incidental to the
general ichthyoplankton surveys, with varying objectives. Since 1979, special sampling in the Niantic
River has been conducted during the occurrence of larval winter flounder. The most comprehensive
sampling has been conducted since 1983, with numerous special studies conducted to identify sampling
biases. Except for entrainment sampling (discussed below), the varying sampling designs prior to 1983
have limited the usefulness of these data in understanding factors affecting the abundance of larval winter
flounder in the Millstone area.

All offshore ichthyoplankton sampling designs have used 60-cm bongo samplers towed from boats at
approximately 2 knots and weighted with various depressors of differing weights. Sample volumes were
determined with General Oceanic flowmeters (Model 2030). Mesh size of the nets have varied with paired

14

333- and 505-fim mesh from 1973 through 1978, exclusively 333-|j.m mesh from 1979 through 1983, and
varying combinations of 202- and 333-|im nets in 1984 and 1985. Tow duration was usually 15 min
(volume filtered of about 200-250 m^^) through 1984, but was reduced to 6 min (ca. 100-150 m^) in 1985
for Niantic River collections. Most tows were oblique, but the tow pattern was changed in 1980 from
continuous (bongo sampler continuously retrieved or let out between surface to near the bottom) to
stepwise (equal sampling time at surface, mid-depth, and near the bottom). In addition, surface and
bottom tows were taken from 1973 through 1978. Bottom tows were taken with a bongo sampler mounted
on a sled. All samples were preserved in 5 to 10% formalin.

Offshore sampling programs can be categorized into four sampling periods. An intensive area-wide
sampling took place from May 1973 through 1975. A much reduced area-wide sampling occurred from
1976 through 1978. Sampling efforts increased for winter flounder larvae in the Niantic River and at one
station in Niantic Bay from 1979 through 1982. Finally, more comprehensive sampling took place in the
Niantic River from 1983 through 1985.

The intensive area-wide sampling program began in May of 1973 to verify the winter flounder larval
dispersal model (Sissenwine et al. 1973); a detailed sampling scheme was provided in NUSCo (1976).
Because sampling started in May 1973, information on larval winter flounder was restricted to 1974 and
1975. Stations 1-13 were sampled in 1974 and 1-16 in 1975 (Fig. 3). During this period, sampling
frequency varied, but usually an oblique tow was made at each station during the day once a week and
at night once every month. Surface and bottom tows were taken every other week during the day and
night at selected .stations. For this report, these data were examined for temporal distribution of winter
flounder larvae in the Millstone area and for the collection efficiency of 333- and 505-|im mesh nets.

In 1976, the ichthyoplankton program was reduced because the previous data were not adequate for
verification of the winter flounder larval dispersion model (Vaughan et al. 1976). The number of stations
was reduced to six (2, 5, 6, 8, 11, and 14). Single day oblique tows were made monthly with additional
surface and bottom tows in May through August. Because of the low frequency of sampling (monthly)
at each station, these data were not useful to examine the life history of larval winter flounder in the
Millstone area.

15

14

10

Figure 3. Location of stations sampled for larval winter flounder at various times from 1976 through 1985.

16

Based on a 1978 evaluation of the offshore ichthyoplankton program (NUSCo 1978b), stations were
further reduced to one (5) with an increase in sampling frequency in 1979. From January through March
and September through December, one day and night oblique tow was taken every other week. During
the remaining months, two day and night tows were made weekly, with all replicate samples processed.
This sampling program has remained the same to the present. For reporting purposes, the station 5
designation was changed to NB in 1983.

Specific sampling for larval winter flounder during their occurrence in the Niantic River began in
1979. Some changes have been made in sampling frequency, station location, and station designation
from 1979 through 1985 (Table 3). The Niantic River sampling was re-designed for 1983, based on the
recommendations of a larval winter flounder workshop held at NUEL in October 1982. The changes
included special studies to reduce sampling biases, resulting from tidal and diel larval behavior. Identification
of sampling biases with special studies in 1983 (NUSCo 1984) and 1984 (NUSCo 1985) limited the
usefulness of data collected previously in 1979-82.

Starting in 1983, ichthyoplankton samples for winter flounder larvae were taken in Niantic River at
stations A, B, and C and in mid-Niantic Bay at station NB (Fig. 3). To ensure mid-depth and near
bottom sampling, the length of tow line necessary to sample the mid-water and bottom strata was based
on water depth and the tow line angle measured with an inclinometer (NUSCo 1984). Nets with 333-^im
mesh were used in 1983. Paired 202- and 333-nm mesh nets were towed in 1984 through mid- March and
only 333-iim mesh nets during the remainder of the season. In 1985, 202-|im mesh nets were used through
the first week of April and 333-|im mesh nets during the remainder of the season. Medusae of a potential
predator, the lion's mane jellyfish {Cyanea sp.), were sieved (1-cm) from the samples at the three river
stations and measured volumetrically (ml). These data were compared to mean weekly medusoid diameter
in the river (Miller et al. 1986) and a diameter to volume relationship was used to estimate abundance of
medusae.

Sampling time and frequency varied during the 1983-85 surveys. In 1983, sampling time in the Niantic
River was systematically varied during daylight and night and at station C sampling was varied over four
tidal stages (high, low, mid-ebb, and mid-flood). At each of the three river stations, day and night tows

17

Table 3.

Summary of sampling in the Niantic River for larval vs^inter flounder.

Year

Sampling frequency Replicates Stations

1979 day - weekly . 2 2

1980 day and night - weekly 4 2

1981 day and night - weekly 4 1,2

1982 day and night - weekly 2 1,2

1983 day and night - twice weekly 1 A, B, C

1984 day and night - twice weekly 1 A^ B, C

1985 day and night - twice weekly^ 1 A, B, C

Day samples only through the first week of April; day and night samples dunng the remainder
of April; night samples only duritig the remainder of the season.

were made twice weekly (Monday and Thursday or Tuesday and Friday). In 1984 and 1985, from the
beginning of sampling (mid to late February) through the fu-st week in April, single tows were made during
the day twice weekly within 1 h of low slack tide. During the last 3 wk of April, single-bongo tows were
made twice weekly day and night. The day samples were collected within 1 h of low slack tide and the
night samples during the second half of a flood tide. During the remainder of the season until the
disappearance of larvae at each station, tows were made twice a week only at night during the second half
of a flood tide.

laboratory sample processing has varied (Table 4). Through 1977, whole samples were processed
and all winter flounder larvae were measured. Subsequently, samples have been split based on the
abundance of larvae and up to 50 winter flounder larvae were measured. When a subsample of larvae
was measured, the length -frequency distribution was adjusted by sample density. Prior to 1983, measure-
ments were in total length and since then have been in standard length (tip of snout to end of notochord).
The difference between total and standard length measurements were only apparent for larvae in the latter
stage of metamorphosis when the caudal fin rays extended past the end of the notochord; these larger
larvae were collected infrequently. From 1973 through 1976, both paired 333- and 505-nm samples were
processed, but length measurements taken only in 505-|im samples m 1976. In 1977 and 1978, only the
333-nm samples from the paired 333- and 505-^im mesh nets were processed. From 1979 through 1982,

18

both replicated 333-|im samples from each bongo tow were processed. Since 1983, only one of the two
bongo sampler replicates collected in the Niantic River was processed in the laboratory and the develop-
mental stage of each measured larva recorded. The five stages were defmed as:

Stage 1, The yoUc sac was present or the eyes were not pigmented (yolk-sac larvae)

Stage 2. The eyes were pigmented, no yolk sac was present, and no fm ray development

Stage 3. Fin rays were present, but the left eye had not migrated to the mid-line

Stage 4. The left eye had reached the mid-line, but juvenile characteristics were not present

Stage 5. Transformation to juvenile was complete and intense pigmentation was present near the
caudal fin base

Because few Stage 5 larvae were collected, their abundance and distribution were not examined.

Table 4. Summary of mesh size and laboratory processing of larval winter flounder

samples.

Sampling mesh Sample No. larvae

Year size ( nm) splitting measured

1974-76 333,505

1977 333

1978-83 333

1984-85 202,333

larval data analyses were based on standardized densities per 500 m of water sampled. Weekly mean
densities were used because of varying sampling frequencies. For comparisons of data in the 1981-85
period, daylight samples during 1981-83 from the last week of April through the end of the season were

19

no

all

no

all

yes

up to 50

yes

up to 50

excluded. During these weeks in 1984 and 1985, daylight samples were not collected because these samples
underestimated abundance due to diel behavior of the older larvae, which apparently remained near bottom
during the day and were not susceptible to the bongo sampler (NUSCo 1984).

Typically, the distribution of larval abundance over time is skewed, with a rapid increase to a maximum
followed by a slower decline. This skewed density distribution results in a sigmoid-shaped cumulative
distribution and the time of peak abundance is the time at which the inflection point occurs in the
cumulative distribution. The cumulative Gompertz function (Draper and Smith 1981) was chosen to
describe the cumulative distribution data because the inflection point of the Gompertz function is not
constrained to the central point of the sigmoid curve. The fonn of the cumulative Gompertz function
used was:

Q = a(exp(-|3e"'^'l) (6)

where Q = cumulative density at time t

a = total or asymptotic cumulative density

P = location parameter
k = shape parameter
t = time in days from February 15

The origin of the time scale for our data was set to the 15th of February, which is when winter
flounder larvae generally appear in the Niantic River. The parameter a was used as an index to compare
annual abundances.

The derivative of the above cumulative function with respect to time yields a "density" function which
directly describes the larval abundance over time. This density function has the form:

4 = apA:(exp[ - kt{ - pe " '"}]) (7)

where dt = density at time t

where all the parameters are the same as in the cumulative function (Equation 6), except for a, which was

20

rescaJed by a factor of 7 because the cumulative densities were based on weekly means and thus accounted
for a 7-d period. Time of peak abundance was estimated as the date t{ corresponding to the inflection
point of the cumulative function defmed by its parameters P and k as:

^. = -f- (8)

Least-squares estimates and asymptotic 95% confidence intervals for these parameters were obtained by
fitting Equation 6 to the cumulative abundance data using nonlinear regression methods (SAS Institute 1985).

The cumulative Gompertz function was used to examine temporal and spatial distribution of larval
winter flounder from data collected in the 1974-75 offshore study, entrainment sampling in 1976-85, and
special larval winter flounder sampling in 1981-85. The stations sampled during 1974 and 1975 were
grouped in relation to their location to the Niantic River: Niantic River (1 and 2); mouth of the Niantic
River (3, 4, 15, and 16); mid-Niantic Bay (5, 11, and 12); Jordan Cove (6 and 13); Twotree Island Charmel
(7 and 8); and Offshore (9, 10, and 14).

Time-based harmonic regression models were also used with abundance data from station 5 in Niantic
Bay (1979-85) and the entraioment sampling station EN (1976-85) to describe fluctuations in abundance
(see Fish Ecology section for detailed methods).

Special studies

The only station in the Niantic River with strong tidal currents was C. To determine the effect of
tidal currents on sample densities of larvae, 24-h studies were conducted in 1983 and 1984. Samples were
collected at 2-h intervals over a 24-h period on April 28 and May 9 in 1983 and March 12 and March 19
in 1984. Tow duration was 15 min with paired 333-^lm mesh nets in 1983 and 6 min with paired 202-
and 333-}jm mesh nets in 1984. These data were examined to determine if tidal currents caused sample
density biases.

Larval import and export studies were conducted at the mouth of the of the Niantic River from 1983
through 1985. Stationary tows were taken by mooring the boat to the Niantic River Highway Bridge in
the middle of the channel. Bongo samplers were deployed off each side of the boat with one at mid-water

21

and the other near bottom. In 1983, samples were collected at the time of maximum ebb and flood tidal
currents during three tidal cycles (two cycles on May 9 and one on May 16). In 1984 and 1985, samples
were collected hourly except for 1 h before and after slack tidal currents during five tidal cycles (April 4
and May 8 in 1984; March 28, April 29, and May 28 in 1985). The 1984 and 1985 data were combined
along with current velocity from the flowmeters to calculate the net exchange of larvae leaving and entering
the river.

Ebb and flood tide velocity measurements used in estimating net larval exchange may not have been
comparable due to the different widths of the channel at the point of sampling. Due to the length of the
mooring line tied to the bridge, the actual sampling location was approximatedly 10 m north of the bridge
during a flood tide and approximately 10 m south of the bridge during an ebb tide. The comparability
of velocities was investigated by fitting a second order polynomial equation to the water velocity measure-
ments over time during the five flood and ebb tidal phases sampled in 1984 and 1985. Because there is
minimal freshwater input into the Niantic River, the area under the fitted curves for flood and ebb tides
should be similar in magnitude. If the areas differ, then adjustments to velocity measurements of either
tidal stage could be made to make the areas similar and velocities comparable (NUSCo 1986a).

The effects of mesh size and tow duration on net extrusion of larval winter flounder were examined.
Comparisons of mesh size were examined in the laboratory (NUSCo 1986a) and in field studies (NUSCo
1985). In the laboratory, meshes of 202, 333, and 505 \im were compared. An apparatus was constructed
such that the velocity of water could be regulated as it passed through a chamber covered by the various
meshes with a similar cross-net velocity (ca. 20 cm/sec) as encountered in field sampling. Ten laboratory-
reared yolk-sac to first-feeding larvae (ca. 3-4 mm) were placed in the chamber. The flow was maintained
for 15 min, the chamber was removed, and the number of larvae retained was counted. From 9 to 18
tests were completed for each mesh. Field comparisons of 333- and 505-nm mesh nets were based on
492 bongo tows made in 1974 and 1975, which examined the number of larval winter flounder by 1-mm
size classes. Comparisons of 202- and 333-|j,m mesh nets were available from 28 bongo tows in 1984 and
were based on the sample densities of Stage 1 and eady Stage 2 larvae. The effect of tow duration on
sample density was made in 1984 with consecutive 6- and 15-min tows in the Niantic River using 333-nm
mesh nets (16 comparisons). A Wilcoxon signed-ranks test was used to compare the paired samples and
test for significant differences (p^0.05) due to mesh and tow duration.

22

Otoliths from larval winter flounder collected in the Niantic River during 1984 were examined to
determine if an age-length key could be constructed from daily increments (NUSCo 1985). At least one
sample each week from all Niantic River stations was preserved with 95% ethanol and processed to obtain
approximately 50 larvae, if possible. All otoliths removed (1 to 4) from a larva were mounted and
examined with a compound microscope connected to a video monitor that provided a magnification of
approximately 5,000 X. If individual otoliths differed in size, the larger pair was assumed to be the sagitta
and used for counting increments. If no size difference was found, the otolith with the most distinct
increments was used.

Winter flounder larvae were reared in the laboratory during 1985 to determine developmental time
and to verify daily otolith deposition (NUSCo 1986a). To examine the effect of starvation on growth,
larvae in one aquarium were not fed. Known-age larvae were routinely sacrificed to obtain otoliths for
aging verification and information on growth rate. Sampling frequency varied, with almost daily collections
during early development to approximately biweekly during later development when few larvae remained.

Post-larval studies

Abundance and distribution

The CPUE of juveniles smaller than 15 cm taken in the Niantic River during the spawning season
was determined in a manner similar to that for adults. Their abundance at the trawl monitoring program
stations was also examined. Numbers of these fish, most of which were age 1 , provided information on
the relative strength of year-classes produced in local waters. In addition, during the surveys of 1981 and
1982, 6- to 15-cm juveniles were marked with freeze-brands to obtain abundance estimates using the Jolly
model.

The abundance and distribution of young-of-the-year (age 0) winter flounder were first examined
during 1976 through 1978. Brief field studies were conducted in summer using various seines and trawls
and diver observations in the Niantic River (Table 5). Because of the small effort and difficulties in
quantifying diver observations without bias, these studies did not provide useful information and will not
be discussed further.

23

Table 5. Summary of Niantic River post-larval juvenile winter flounder studies from 1976 through
1985.''

Year

Method

Period
sampled

Areas or
stations
sampled

Times
sampled

Comments

1976

otter trawl

May 27-Jul 23

4-8

3

Confirmed Niantic River

seines

Jun 16

5

1

as nursery area

1977

otter trawl
diving obs.

May 17-Jul 29
Aug 9-Sep 9

3
12

5
2

Inconclusive - few taken
Rarely seen except in lower
river

1978

diving obs

Jul - Sep

11

3

Abundance estimates made
based on observed densities
and bottom areas

1981

free/e-branding

Apr - May

4

--

6 - 15 cm juveniles branded
during part (1981) or

1982

freeze branding

Feb - May

4

all (1982) of adult surveys.
Abundance estimates unreli-
able because of high marking
mortalities

1983

beam trawl

May 18-Oct 12

4

21

Abundance, growth and
mortality estimates made
from 1983 through 1985

1984

beam trawl

May 24-Sep 26

3

19

A seine was also used several
times in 1983, but few were
taken.

1985

beam trawl

May 23-Sep 19

2

18

.Juvenile (^15 cm) winter flounder abundance estimated by CPUE also available for
1976 through 1985 from adult winter flounder surveys in Niantic River and from trawl
monitoring program data.

A quantitative study of post-larval young-of-the-year winter flounder in the Niantic River began in
1983 and has continued through the present. One of the four stations established then (LR) was sampled
in each year (Fig. 2). Station CO was sampled from 1983 through July 1984, when it was replaced by
WA because continued heavy accumulations of the alga Enteromorpha clathrata hampered sampling at the
former location. Stations SP and CH were used only in 1983 and were dropped because flounder were
less common there and catches more variable; data from these two stations will not be included in this
report. All stations contained habitat preferred by juvertile winter flounder, with sandy to muddy bottoms

24

in shallow (ca. 1-2 m) water adjacent to eelgrass beds (Bigelow and Schroeder 1953). Each was sampled
once every week from late May through late September or early October during daylight within about 2
h before to 1 h after high tide.

A 1-m beam trawl was used with interchangeable nets of 0.8-, 1.6-, 3.2-, and 6.4-mm bar mesh. A
tickler chain was added in late June of 1983 to increase catch efficiency. In 1983, triplicate tows were
made using one of the nets, which was changed as young grew during the season. In 1984 and 1985, two
nets of successively larger mesh were used during each sampling trip to collect the entire available size
range of young. This helped to eliminate a bias that was found in 1983, when some of the older and
larger specimens apparently were able to avoid the 0.8-mm mesh net used without a tickler chain (NUSCo
1984). A change to the next larger mesh in the four-net sequence was made when young had grown
enough to become susceptible to it. The larger meshes also reduced the amount of detritus and algae
retained. Two replicates with each of the two nets were made at both stations; the order in which the
nets were deployed was chosen randomly. Distance of each tow was estimated by letting out a measured
line attached to a lead weight as the net was towed. Tow length increased from 50 to 75 to 100 m as the
number of fish decreased throughout the summer. For data analysis and calculation of CPUE, the catch
of both nets used at each station was summed and standardized to giVe a density per 100 m of bottom
covered by the beam trawl.

Growth and mortality

Young winter flounder were measured unpreserved in the field or laboratory to the nearest 0.5 mm
in total length (TL). During the first few weeks of study, standard length (SL) was also measured because
many of the specimens had damaged caudal fm rays and total length could not be taken. The relationship
between the two lengths was determined by a functional regression and used to convert SL to TL:

rL= -0.10+ 1.198 (5'L)(«= 136, r^ = 0.92) (9) .

To calculate mortality, all young were assumed to comprise a single cohort. A catch curve was
constructed with the natural logarithm of density plotted against week. The slope of the descending
portion of the curve provided an estimate of Z, the weekly rate of instantaneous mortality. Once Z was
determined, daily survival was estimated as exp(-Z/7), weekly as exp(-Z), and monthly as exp((-Z)(30.4/7)).

25

Impingement

The number of winter flounder impinged on the traveling screens of MNPS from October 1972
through September 1985 was estimated using techniques described in the Fish Ecology section of this
report. The chronology of impingement sampling at MNPS was also given there. Meteorological data
were obtained from MNPS operating records to examine certain specific instances of high impingement,
length-frequency data offish impinged from 1976-77 through 1984-85 were also examined. The sex and
reproductive condition of impinged winter flounder taken just prior to and during the spawning 1982 and
1983 seasons were recorded using methods and criteria described previously.

Details regarding studies leading to the construction, installation, and operation of a fish return
sluiceway at MNPS Unit 1 were summarized in the Fish Ecology section. Data and fmdings pertinent to
the winter flounder will be discussed in this section. Additional information may be found in NUSCo
(1981b, 1986b).

Cntrainment

Winter flounder larvae entrained at MNPS were collected at station EN (Fig. 3). Sampling has been
conducted since April 1973 as part of a general ichthyoplankton sampling entrainment program. Because
of sampling problems, data collected through June 1975 were not used to estimate entrainment numbers,
but were the basis for the sampling design beginning in July 1975. Entrairmient samples from the 1976-85
larval winter flounder seasons (primarily March through May) provided the longest time-series of data for
which annual comparisons could be made. The only changes in sampling design were sampling frequency
and replication. For 1976-82, three replicates were collected day and night on 3 d each week. In 1983,
sampling frequency was changed to one sample during the day and night on 4 d per week. Sampling
alternated weekly at the discharge of Units 1 and 2, whenever plant operations permitted. Approximately
400 m'' of water were filtered through a 1.0-m diameter, 3.6-m long, 333-nm mesh conical plankton net.
Laboratory processing methods and some data analyses were described previously in this report. Additional
details may be found in the Fish Ecology section, including the method used to estimate annual entrainment
numbers.

26

An entrainment mortality study was conducted in 1983 (NUSCo 1984). Samples of entrained winter
flounder larvae were collected downstream from the MNPS discharges with a 0.5-m diameter, 1-m long,
333-jim mesh plankton net. Dead larvae were removed from the sample and counted. Live larvae were
held in flow-through chambers in effluent water. Holding time was 2 or 4 h to simulate retention in the
quarry with three or two units in operation, respectively. Following effluent holding, chambers were
moved to ambient flow-through water and observed daily for latent mortality over a 96-h period.

The thermal tolerance of larval winter flounder was examined (NUSCo 1975). Larvae were grouped
as pre-metamorphosis ( < 5 mm) and metamorphosing ( ^ 5 mm). Larvae were exposed to a AT of 13 °C
(acclimation temperature of 8 °C) for 1 to 9 h and survival was monitored. The critical thermal maximum
for the two groups was also examined, where larvae held at 8 °C were exposed to an increase of 1 °C per
min until death. The temperature at which complete mortality occurred was the estimated critical thermal
maximum of larval winter flounder.

Impact assessment

A population dynamics model was developed under the direction of Dr. Saul Saila of the University
of Rhode Island for impact assessment during the projected life of the plant and for a recovery period
following decommissioning. This model incorporates hydrodynamic, concentration, and population
submodels in a simulation of the effects of MNPS operations on the Niantic River stock of winter flounder.
Data from both NU studies and the scientific literature were used in the model. The methods and
procedures used in its development and may be found in progress reports to NUSCo by Sissenwine et al.
(1973, 1974, 1975) and Vaughan et al. (1976). Aspects of the model were published by Hess et al. (1975).
The final form of the model presented by Saila (1976) was summarized and used with updated information
in the Environmental Report for MNPS Unit 3 (NUSCo 1983c). A brief summary of the results and
conclusions of the latest model application will be given in this report.

27

RESULTS AND DISCUSSION
Adult abundance studies

Abundance in the Niantic River

The Niantic River winter flounder population is demographically open and therefore subject to
immigration, emigration, natural death, and removal by fishermen. Although attempts to estimate the
abundance of Niantic River winter flounder using mark and recaptures techniques began in 1973, the first
reliable estimates were not made until 1976. The sampling intensity was too low and effort spread across
too much area and time in 1973 and 1974 for estimates to be made by any means. In 1975, a more
intensive sampling program was undertaken in the river. Fish were marked by fin clips, but recaptures
were not marked. Nevertheless, the Jolly (1965) model, a multiple mark and recapture method, was applied
to the data. Multiple recaptures were mathematically simulated, but the resulting estimates were judged
to be inadequate because of large errors in parameter estimates. In addition, the 1975 survey data were
not similar to later years for calculation of CPUE or other relative abundance indices. The March 31
start meant that the survey missed most of the spawning and was not temporally comparable to later
years. Most tows were very brief (average of 5 min) and defmition of stations differed from later years.

Surveys expressly designed to estimate abundance of open populations usmg the stochastic model of
.lolly began in 1976. The Jolly model is an extremely powerful general formula that uses all the information
provided by the mark and recapture experiment and provides the most efiicient estimates as long as failures
do not occur in basic assumptions (Cormack 1968; Southwood 1978; Begon 1979). The second measure
of abundance for winter flounder over the past 1 1 yr was the CPUE during a 4-wk period from mid-March
through early April, the only time including comparable data for all surveys. The median CPUE was
used as the most appropriate catch statistic as the trawl catch data were not normally distributed and were
positively skewed.

Annual Jolly composite abundance indies were calculated for 1976-86 using the mark and recapture
data (Table 6). The 1976-82 surveys extended into May, but later ones were made only during the period
when most spawning had occurred and ended by mid-April. Consequently, the earlier data were re-analyzed

28

to conform to the same criteria for ending surveys after 1982 (Appendices I - XXII). From 5 to 8 wk of
mark and recapture data aimually were available for the Jolly model. The largest number of fish branded
in one year was in 1981 (6,726) and totals have since declined each year through 1986 (2,790). Fewest
recaptures were made in 1985 (143; 4.7% of the total branded) and the most in 1980 (433; 10.0%); the
average armual recapture rate was 6.7%.

Table 6. Yearly mark and recapture data for Niantic River winter flounder studies from 1976

through 1986.

Year

Dates

No. of

No.

No.

%

sampled*

weeks

marked

recaptured

recaptured

1976

Mar 1 - May 4

10

9,856

699

7.1

Mar 1 - Apr 13

7

6,479

453

7.0

1977

Mar 7 - May 10

10

6,860

623

9.1

Mar 7 - Apr 12

6

3,737

257

6.9 -

1978

Mar 6 - May 16

11

8,403

729

8.7

Mar 6 - Apr 25

8

4,417

360

8.2

1979

Mar 12 - May 15

10

8,105

491

6.1

Mar 12 - Apr 17

6

4,067

241

5.9

1980

Mar 17 - May 6

8

7,625

961

12.6

Mar 17 - Apr 15

5

4,313

433

10.0

1981

Mar 2 - May 3

10

10,458

822

7.9

Mar 2 - Apr 14

7

6,726

469

7.0

1982

Feb 22 - May 1 1

12

11,076

901

8.1

Feb 22 - Apr 6

7

5,795

270

4.7

1983

Feb 21 - Apr 6

7

5,196

363

7.0

1984

Feb 14 - Apr 4

8

3,740

197

5.3

1985

Feb 27 - Apr 10

7

3,024

170

5.6

1986

Feb 24 - Apr 8

7

2,790

175

6.3

For 1976-82, first line gives data for the entire survey and second for the spawning season.
Minimum size for marking was 15 cm during 1976-82 and 20 cm thereafter.

The Jolly composite abundance indices showed that the Niantic River winter flounder population was
relatively stable from 1976 through 1980, increased to a peak in 1982, and declined to an 11-yr low in
1986 (Table 7; Fig. 4). Using the catch offish between 15.0 and 19.9 cm, the estimates for 1983-86 were
also adjusted upwards for direct comparability between that period and 1976-82, as the estimates for the
earlier years included all fish larger than 15 cm. The annual trends in median CPUE generally corresponded

29

with the Jolly composite index of abundance until 1982 (Table 8; Fig. 4). The CPUE in 1982 (42.6) was
nearly the same as in 1981 (43.4), but the abundance index increased 72% (28,693 to 49,439). However,
the Jolly estimate during 1982 was relatively imprecise with a large confidence interval (± 16,666). The
decline in CPUE for fish larger than 20 cm from 1983 (22.1) to 1984 (12.8) and 1985 (12.6) was much
greater than for the abundance index (29,912 to 29,282 and 21,632). The JoUy index for 1986 (8,252)
declined greatly from 1985, but the CPUE decreased by only about 20%. The CPUE for 1984-86 indicated
population levels about one-half of that during 1976-80, which also contradicted the Jolly abundance
indices. The apparent differences between abundance indices were evaluated below by examining meth-
odologies used in obtaining the estimates.

Data from the trawl monitoring program for the five stations outside the Niantic River were used in
calculating a median CPUE during January through April of each year. This period overiapped the river
spawning and allowed for an increase in available data. The median CPUE showed relatively low densities

Table 7. Compo.site index of abundance for Niantic River winter flounder from

1976 through 1986.

Year No. of Composite abundance Adjusted

values used — 2 standard errors^ abundance

1976

3

1977

3*^

1978

3"=

1979

2 =

1980

3^=

198!

3

1982

3

1983

3

1984

3

1985

3

1986

3

Composite al
- 2 standarc

Sundance
1 errors^

21,795 ±

4,768

18,183 ±

5,088

14,620 ±

3,494

18,709

18,159 ±

3,976

28,693 ±

6,640

49,439 - 16,666

29,912 ± 7,042 34,997

29,282 ± 10,518 36,310

21,632 ± 9^345 26,175

8,252 ± 2,723 9,663

For winter flounder larger than 15 cm during 1976-82 and 20 cm thereafter. Abundance
adjusted to all fish larger than 15 cm for 1983-86.

b

Only N] excluded.

No values of N excluded.

30

of adult winter flounder outside the river in winter and early spring, with little change in the catch of
adults over the l!-yr period. Values ranged from 1.8 to 5.3 in all years except 1981, when a peak value
of 8.2 was found. Although the Niantic River spawning population apparently reached its lowest level in
1986, the median outside the river was the third highest (4.7). The reason for this difference in abundance
and distribution is unknown. Water temperature is an important factor in winter flounder distribution.
However, based on MNPS operating records, water temperature in 1981 was the closest to the annual
February-April mean over the U-yr period and the mean for 1986 was only slightly higher than 1985.
The coldest year of the series was 1976 and the warmest was 1983.

Table 8. Mean and median CPUE of Niantic River winter flounder larger than 15 cm from

1976 through 1986 during the period of mid-March through mid-April.

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

Total tows made

112

154

106

93

112

109

90

135

145

156

179

Tows used for CPUE

85

123

88

77

91

97

87

134

143

155

173

% of tows used

76%

80%

83%

83%

81%

89%

97%

99%

99%

99%

97%

Mean CPUE

37.6

29.8

24.2

38.8

41.4

48.4

47.6

31.5

16.9

15.6

14.4

Standard deviation

33.5

25.8

16.0

33.6

32.3

31.1

30.6

16.3

10.2

8.0

9.0

Coeff. of variation

89%

86%

66%

87%

78%

64%

64%

52%

60%

51%

63%

Median CPUE

28

24

19.6

26.8

31.5

43.4

42.6

30.8

15.0

14.7

12.0

95% CI

22.5

20.0

16.2

22.4

26.1

36.2

35.2

24.1

13.6

12.7

10.6

-37

-30

-25

-38.4

-42.5

-51.4

-48.8

-33,9

-16.6

-15

-14.6

('oeff. of skewness^

2.33

1.45

1.18

1.67

1.54

1.24

1.13

0.96

1.48

1.13

1.25

Zero when data are distributed symmetrically

Both the Jolly model and its application to the Niantic River winter flounder were evaluated several
times by NUEL (NUSCo 1980, 1983b, 1986a). In the first two reviews, data were examined for the
violation of assumptions or conditions of the model generally as set forth by Bishop and Sheppard (1973),
Roff" (1973a, 1973b), Southwood (1978), Begon (1979), Balser (1981), and Amason and Mills (1981).
Most assumptions were met, although the possibility existed that some emigration outside the survey area
was not permanent and marked winter flounder re-entered the river. This assumption requires that all
emigration from the study area be permanent and therefore indistinguishable from death in the model. If

31

o 2

70

60-

50

< 5

i^9

LJ 40-

^ o 30-

^g 20-
z <

!^ O

10

CPUE
(>15 cm)

/

I
I

/

/

JOLLY
(>20 cm^

/ T

1 /
/

i ;

):

1

OLLY ■
>15 cm

t-

^^^

/

/ ^

/

/

A

\

\

A A "'s

(

)

CPUE
(>20 cm'

1

T

76 77 78 79 80 81 82 83 84 85 86

YEAR

Figure 4. Annual median trawl CPUE and Jolly abundance index (+2 standard errors) for Niantic River winter

flounder from 1976 through 1986. Jolly index and CPUF, adjusted for fish 15 cm and larger in 1983-86
and shown by * and A, respectively.

the catchability of marked and unmarked fish was not equal, sampling eirors of unknown magnitude
resulted. Jolly abundance estimates were also compared with those obtained using the Fisher- Ford and
Manly-Parr models in 1980 and as results were generally similar, the simpler and more powerful .lolly
model remained in use (NUSCo 1981a).

The latest review (NUSCo 1986a) rigorously examined the model itself, assumptions, reliability of
results, and its particular application to the winter flounder population. The Jolly model has been criticized
because its flexibility is provided by many unknown parameters which must be estimated. These estimates
may be imprecise unless sampling intensity is relatively high (Cormack 1979; Buckland 1980; Nichols et
al. 1981; Hightower and Gilbert 1984). The review concluded that sampling intensity and recapture rates

32

may be imprecise unless sampling intensity is relatively high (Cormack 1979; Buckland 1980; Nichols et
al. 1981; Hightower and Gilbert 1984). The review concluded that sampling intensity and recapture rates
of Niantic River winter flounder were rather low and may have resulted in errors of the estimates.
Furthermore, estimates of recruitment (Jolly's B) were undoubtedly unreliable because they accumulated
errors from other parameters in the model (also see Amason and MUls 1981 and Hightower and Gilbert
1984). Adding recruitment estimates to an initial estimate of abundance (Jolly's N), as done in previous
years to obtain absolute abundance estimates, was shown to be highly inaccurate. This led to the
formulation of the composite index of abundance based on the Jolly model, which used the average of
the central estimates of N and a pooled variance estimate (NUSCo 1986a).

Using results from a simulation study by Hightower and Gilbert (1984) and based on sampling
intensities of 3 to 5.4%, population sizes of 20 to 40 thousand, and survival of about 0.90 ("deaths" 'here
are mostly due to emigration from the Niantic River), it was assumed with 95% confidence that errors in
estimating abundance using the Jolly model ranged from 25 to 50%. These levels of accuracy are sufficient
for management purposes, but are not within the 10% level of error that Robson and Regier (1964)
recommended for research investigations. Hightower and Gilbert (1984) demonstrated that sampling in-
tensities had to be doubled to increase the accuracy from 25 to 50%. Substantially higher and most likely
infeasible levels of effort would be required to achieve sampling intensities necessary for the accuracy level
of 90% for current population sizes in the Niantic River.

The CPUE was also examined for bias and accuracy (NUSCo 1983b, 1986a). The standardization of
fishing effort is difficult and although the catchability of a species is presumed constant, the fishing gear
can vary in efficiency and can be affected by subtle changes in its use, rigging, or deployment from different
vessels (GuUand 1983). Nevertheless, repeated surveys using relatively consistent methods can provide an
index of abundance free of difficulties caused by possible changes in catchability. Among the factors
examined that could have influenced Niantic River winter flounder CPUE were changes in boats, trawling
methodology, and variable annual conditions in the Niantic River.

With some exceptions, the vessels used during sampling changed annually from 1976 through 1981
(Appendix XXIII). Several comparisons between boats showed significant differences in catches among
years (NUSCo 1983b), indicating possible differences in fishing power. Since 1981, two vessels identical
except for rigging have been used. Northeast /, rigged exclusively for trawling, consistently caught more

33

winter flounder in comparable tows than Northeast II, designed for lobster pot hauling and modified for
trawling.

Another factor influencing CPUE was the distribution of effort among stations in the river (Appendix
XXIV). Effort was most extensive in the lower river channel and adjacent shallows in 1976-77 and
occurred mainly in the channel during 1978-80. Through 1980, it was believed that heavy concentrations
of algae and detritus found in the upper river greatly reduced the number of winter flounder found there.
However, in 198 1 many winter flounder were found in the upper river and sampling effort has predominantly
shifted there duriing the past 6 yr. Detrital loads probably also have altered the efficiency of the trawl and
may have affected CPUE. Quantitative comparisons indicated significantly longer tow times in the upper
river in 1984 than in 1983 or 1985-86. This was most likely due to the net filling with material as it was
towed, thereby increasing drag. Decreases in average tow time have been due to lesser amounts of detritus
as well as the purposeful avoidance of the worst towing areas in station 51. The practice of concentrating
effort where most winter flounder were present prior to 1983 also may have had some consequence;
increased medians may have resulted from limiting the number of tows with fewer fish.

Although each measure of abundance has inherent errors, the reasons for the disparities between the
.loUy index and CPUE are unknown. The standardization of tows to a uniform distance by station in
1983 and subsequent years lessened the variability in CPUE as seen by the smaller confidence interval
about each median and greater correspondence between the median and mean. The Jolly indices for
1984-86 were less precise with relatively large confidence intervals, which could have accounted for some
of the differences observed in the trends. Because of the small number of fish marked in 1986, the Jolly
estimate for that year may have been inaccurate. Although there were indications that the population
probably declined from 1985, the decrease would have been proportionately less if the CPUE was more
reliable than the Jolly composite index.

Some difi'erences between CPUE and the Jolly composite index could be related to changes in winter
flounder distribution over time. Possibly, most winter flounder were present only in the lower river during
the 1970s and despite low to moderate population levels, high CPUE were obtained because of their
concentration in the relatively smaller portion of the river that was sampled. Then, in 1980, for unknown
reasons, winter flounder began to use the upper river as well. Although more abundant, they would have
been less concentrated throughout the river and lower CPUE were obtained. Alternatively, winter flounder

34

may have always been present throughout the river and the Jolly indices from 1977 through 1980 were
inaccurately low to an unknown degree because only a portion of the population was sampled. This was
previously suspected for the 1980 survey, when a large percentage of relatively small and stationary winter
flounder were found and no samples were taken in the upper river unlike following years (NUSCo 1983b,
1985). Therefore, CPUE may have more realistically measured abundance from 1976 through 1980.
Examination of data from 1981 through 1986 showed that median CPUE values for station 1 and 2 in
the lower river were very similar to those from the upper river (within 4 fish per tow), except for 1983
(13.2 less in the lower river), so CPUE appears to be relatively consistent among areas. As surveys and
methods are presently more standardized, further comparisons of CPUE and the Jolly index may be made
in forthcoming years and the relative accuracies of the two measures of abundance can be reassessed.

Harmonic regression models

Another measure of winter flounder abundance throughout the MUlstone area was the development
of time-based harmonic regression models. I x)g-tr£insformed data from six stations of the trawl monitoring
program (see Fish Ecology section) were used to describe the fluctuations in abundance of winter flounder.
Models having data from October 1976 through September 1984 forecasted catches from October 1984
through September 1985 and the actual catches were then compared to those predicted (NUSCo 1986a).
Similar models were reported in NUSCo (1984, 1985) for 1982-83 and 1983-84 data. Results showed that
models for stations other than NR (Niantic River) were not satisfactory. Terms corresponding to a
sine-cosine function describing an 8-yr period were significant for most models in 1985, as were terms for
7 or 6 yr during 1984 and 1983. Since these terms represented the entire time-series of data at the time
of model development, this indicated either insufficient data or a lack of a repetitive pattern of abundance.
Terms of less than 1 yr were also found for most models and were probably related to aimual cycles of
abundance due to local movements and recruitment of juveniles into the trawl catch. Except for NR
(0.71), R values for each model remained low (0.38-0.53). However, this is a typical result for a species
taken year-round in samples. Forecast errors remained high in 1985 (65-279%; 128% for NR), although,
in most cases, improved each year since 1983. This was an indication that the models were perhaps
providing better predictability.

Many factors have influenced trawl monitoring program catches, as they have in the Niantic River
abundance surveys discussed previously. Despite its relatively high abundance in the catch (43% of the

35

lO-yr total, ranked first), typical high variability along with relatively low effort makes analyses of these
data problematical. In addition, the mixture of stocks present at most stations during many months of
the year (see Stock Identification below) makes data from the trawl monitoring program difficult to
interpret and of limited use in assessing the impact of MNPS operations.

Regional trends in abundance

Data from other sources were examined for comparisons in abundance as historically the abundance
of winter flounder has been known to fluctuate, showing various periods of increases and decreases
(Perlmutter 1947; Howe 1975; Ketschke 1977; Jeffries and Terceiro 1985). This feature of winter flounder
population dynamics, demonstrated above for the Niantic River population, also was found to have
occurred in other areas of Southern New England. Jeffries and Terceiro (1985) reported that winter
flounder abundance at a station in Narragansett Bay decreased 86% from 1968 to 1976, but increased
rapidly to reach another peak in 1979. This was followed by a steady decline through 1982. Flounder
abundance at another station in Rhode Island Sound showed similar fluctuations, indicating that the
changes in abundance were not due to a shift in population from inside to outside of the bay. However,
these fmding were based on only one tow per week at each station.

Commercial landings throughout Southern New England have decreased steadily from 11,100 mt in
1981 to 7,000 mt in 1985, although they have remained higher than any year prior to 1980 (NMFS 1986).
Commercial vessel CPUE fell to a historical low in 1985 from a peak in 1981. The National Marine
Fisheries Service (NMFS) offshore trawl surveys found that survey vessel CPUE decreased rapidly from
a maximum in 1981 (3.6 kg/tow) to levels below the long-term average in 1984 (0.8) and 1985 (1.0).
Based on these declines, NMFS considers the winter flounder to be fully exploited and that current catch
levels will probably not be sustained (NMFS 1986).

The Massachusetts coastwide fishery assessment fall survey found an 84% reduction in winter flounder
biomass from 1983 to 1984 (Howe et al. 1985). Commercial landings also have declined 52% in Massa-
chusetts since 1981. Some evidence suggests that overfishing of winter flounder has occurred in Massa-
chusetts (MDMF 1985). Besides decreases in landings, percentages of market-sized "small" and "pee-wee"
fish have increased; relatively high landings were maintained by landing more and more smaller fish. The

36

percentage of fishermen directing their effort towards winter flounder and shift of larger vessels inshore has
exacerbated the problem and serious concern was expressed about the fishery.

The annual geometric mean trawl catch of winter flounder by the CT DEP in eastern Long Island
Sound declined fivefold from 1984 through 1986 (P. Howell, CT DEP, pers. comm.), a decrease even
greater than seen in the Niantic River. Conversely, annual landings from Cormecticut-licensed commercial
trawlers increased threefold from an average of 87,657 kg during 1979-82 to 271,160 kg during 1983-86
(CT DEP, unpublished data). It should be noted that some of the increase in landings in recent years
was due to more accurate reporting by fishermen (E. Smith, CT DEP, pers. comm.). From 13 to 43%
of these fish were caught in eastern Long Island Sound, with increasing proportions (27-43%) for recent
years. Percent landings from outside Long Island Sound decreased during the same period from more
than half to about one-third of the total. At the same time, overall catch-per-trawl-hour decreased from
an average of 41.9 kg during 1979-83 to 30.0 kg in 1984-86.

Life history studies

Reproduction

Sex ratio

The sex ratio of winter flounder larger than 20 cm during the spawning period in the Niantic River
varied from 0.92 to 2.03 females for each male (Table 9). The average from 1977 through 1986 was 1.44;
the latest survey was the only one in which more males than females were taken. Sex ratios of 1.50 to
2.33 in favor of females were also reported by Saila (1962a, 1962b) and Howe and Coates (1975) for other
populations in southern New England.

Size at maturity

Female winter flounder can become sexually mature when they are age 3 or when about 20 cm in
length (Dunn and Tyler 1969; Dunn 1970; Kermedy and Steele 1971; Beacham 1982). More northerly
populations mature at smaller sizes and older ages than in Southern New England. Results of a probit

37

Table 9. Female to male sex ratios of winter flounder taken during the spawning

period in the Niantic River from 1977 through 1986.

1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 Mean C.V.

AH fish captured 1.03 2.23 1.37 2.66 1.42 1.16 1.52 1.07 1.37 0.92 1.48 38%

Measured fish 1.26 1.95 1.21 2.03 1.61 1.50 1.52 1.07 1.37 0.92 1.44 25%

>20 cm

analysis showed that the length of 50% sexual maturation of Niantic River females during 1981-86 was
26.8 cm with a 95% confidence interval of 26.3 to 27.3 cm. On an annual basis, values ranged from 25.1
cm in 1983 to 29.4 cm in 1981. Most of these fish were age 3 or 4. Males can mature at even smaller
sizes (down to 10-12 cm) and earlier ages (2) than females.

Spawning

Winter flounder spawning was followed by noting the weekly change in the percentage of gravid
females larger than 25 cm in the Niantic River. Generally, most spawning was completed by early April
(Fig. 5). Ice in the river prevented starting population surveys earlier in January or February, so for most
years approximately two-thirds of the females examined during late February had spawned before sampling
began. In most cases, spawning appeared to be correlated with water temperature. In relatively cold years
(1977-78, 1982), fewer females spawned during the earlier portion of the survey, whereas in warmer years
(1981, 1983-86) more were spent. No conclusions can be made about 1979 or 1980 (both cooler than
average) because of the late starts to these surveys and because relatively fewer females were examined in
comparison to other years.

Fecundity and egg production

The length-fecundity relationship for winter flounder taken in the vicinity of MNPS was determined
in two independent studies during 1977. In one, all fish were collected in the Niantic River and in the

38

70
60

y 50
<

Ld

o 30-

h-

UJ

o

n-

10

0-t

1977.

1981

\
\

/ \ / \

\J^978/ \ / \ \

'^, 197^/ \ ,./x

^ A \ \

M980..^ / \\ , \

FEBRUARY

MARCH

77 78 — - 79

\

\S

80

APRIL

- 81

70

60

H 501

40

o 30

Ld
O

cr 20

Ld

10

1984 ^-'
\ 1982

\
\
\
\

1986

1983^

1985'

1983^ \

\^

\

\

\

0-<— r-

FEBRUARY MARCH APRIL

82 83 84 85 86

Figure 5. Percentage of adult female winter Rounder in spawning condiUon by week in the NianUc River from 1977
through 1986.

39

second they were caught by trawl in Niantic Bay or were impinged at MNPS. Laboratory methods and
procedures for determining fecundity differed in some respects between the studies. Although findings

Table 10. Length-fecundity and length-weight relationships for winter flounder.

Sample location Type regression

Slope (b) Intercept (a)

Value for 31 -cm Hsh

Length-fecundity

Niantic River

Functional

Niantic Bay

Functional

Rhode Island

Functional

(Saila 1962a)

Newfoundland

Least squares

(Kennedy and

Steele 1971)

Niantic River

Functional

Niantic Ray

Functional

Mass.-R.I

Least squares

(Lux 1969)

Newfoundland

Least squares

(Kennedy and

Females:

Steele 1971)

Males:

LenRth-weight

43 1 ,000

410,000

117
107

3.1441
2.9833

-2.0702
- 1 .904 1

385 g
548 g
379 g

416 g
351 g

Recalculated from Saila's (1962a) published data.

Regression equation in the form: logio fecundity = a + b(logio length in cm).

Regression equation in the form: logio weight (g) = a + b(logio length in cm)
(except Lux 1969, where length is in mm).

40

based on these data were reported previously (NUSCo 1978a, 1983b), they were re-examined for this
report and new length -fecundity relationships were calculated using a functional regression (Table 10).
Using the 1977-86 modal length of 31 cm for Niantic River females for comparison, the fecundity estimate
obtained from the first study was most similar to estimates made using relationships obtained from Saila
(1962a) and Kennedy and Steele (1971). The Niantic Bay data gave comparatively high estimates, but no
reason can be given for the discrepancy between the two studies.

Table II. Annual indices of female spawners and egg production for Niantic
River winter flounder from 1977 through 1986.

Year

Number of
spawning females

(x/O^)

% of population

comprised by
mature females

Mean
fecundity

(xIO^)

Total egg
production index

(x/O^)

1977

5.6

31%

4.8

2.69

1978

5.5

38%

5.1

2.81

1979

4.8

26%

5.3

2.55

1980

3.7

20%

4.7

1.70

1981

10.7

37%

5.3

5.66

1982

18.9

38%

5.7 ■

10.79

1983

15.2

51%

5.6

8.51

1984

12.6

43%

5.7

7.20

1985

10.1

47%

5.9

5.92

1986

3.5

43%

6.5

2.31

From composite index of abundance and percentage of mature females, assuming that all
females 26 cm and larger were mature.

For winter flounder larger than 15 cm during 1976-82 and 20 cm thereafter.

The proportion of females in the population larger than 26 cm was combined with the .lolly index of
abundance to obtain a relative number of female spawners from year to year; 1976 was excluded because
no reproductive data were available then. Spawning females comprised 20 to 51% of the population
(Table 11). Percentages for 1977-82 were lower because they were based on all fish larger than 15 cm
and thus included more immature fish in the abundance estimates. The value for 1980 (20%) was
particularly low and is another indication that a segment of the spawning population was missed then, as
comparatively more smaller, immature fish were caught.

41

The mean fecundity was calculated using the relationship described previously with annual length-
frequency data. Values have been relatively consistent with somewhat greater means found since 1982,
when the start of the surveys was advanced into February. During the past several years, most females
larger than 40 cm were usually found in the Niantic River early in the season and many evidently left the
estuary in March. Surveys during earlier years started after February and probably missed many of these
large winter flounder, resulting in a lower mean fecundity. The mean length of all females 20 cm and
larger in 1980 was only 29.7 cm, in comparison to 31.4 to 32.1 cm for 1979 and 1981-85. This was
additional evidence that larger females were missed during the 1980 survey. In contrast, the 1986 mean
of 33.4 cm was particularly large, indicating that along with decreasing abundance, the female population
was comprised of relatively larger and older specimens.

Egg production indices were determined using Jolly abundance indices with the length, maturity, and
fecundity data. Since the indices reflect both the annual mean fecundity and abundance, the value for
1980 was probably underestimated. The egg production index peaked in 1982 and has declined about
80% since then. Tyler and Dunn (1976) reported that the relationship between length and egg production
of New Brunswick winter flounder varied from year to year, depending upon variable nutrition and females
were found to sacrifice egg production to maintain body weight. It is not known whether fecundity varies
annually among Niantic River winter flounder.

Age and growth

Length-weight relationship

As with fecundity, the length-weight relationships for winter flounder taken in Niantic River and Bay
were recalculated using 1977 data with a functional regression. Once again, the relationship determined
for Niantic River fish appeared to be more consistent with other published regressions (Table 10). The
Niantic Bay relationship gave heavier weights per unit of length; the reason for the difference is unknown.

42

Age and length

In 1977 and 1978, winter flounder were aged by examination of both scales and otoliths; age determined
by both structures agreed well, especially for younger fish (NUSCo 1979). As the use of otoliths required
sacrificing the fish, orJy scales were used in subsequent years. The overall mean lengths-at-age for
1977-1983 combined data showed that winter flounder grew most rapidly during the first several years of
life with considerably reduced annual growth after age 4 (Table 12). Females had greater annual increases
in length than males, especially at ages 3 through 5. The mean lengths of females were significantly greater
than males for fish age 3 and older; this was also noted for many other winter flounder populations (Berry
et al. 1965; Poole 1966; Lux 1973; Howe and Coates 1975; Danila 1978; Beacham 1982).

Table 12. Mean lengths in mm by age of Niantic River winter flounder from 1977

through 1983.

Ixjwer Upper Tenth Ninetieth
Age Sex Number Mean SD CV quartile quartile percentile percentile

1

7

1,259

82

23

28%

65

97

55

118

2

7

1,413

176

27

15%

156

195

142

214

3

7

1.39

212

15

7%

201

223

192

235

3

F

460

266

27

10%

245

284

2.34

304

3

M

220

256

28

11%

237

278

220

292

4

F

246

307

29

10%

289

327

267

.344

4

M

159

291

26

9%

275

.308

260

320

5

174

342

24

7%

325

360

314

370

5

M

150

312

26

8%

295

330

280

358

6

112

363

22

6%

.345

379

333

.391

6

M

90

3.36

25

8%

316

351

303

370

7

78

390

23

6%

374

405

362

419

7

M

57

360

25

7%

337

378

.331

392

8

51

409

27

7%

391

431

378

442

8

M

18

368

31

8%

.345

386

327

426

9

13

428

26

6%

408

447

389

467

9

M

4

400

29

7%

--

--

369

437

10

4

431

17

4%

--

--

422

456

10

M

1

411

--

--

--

--

--

--

12

F

1

443

--

--

--

--

--

--

43

The coefficients of variation for length by age were relatively consistent and ranged from 6 to 11 %
for age 3 through 8 females and males. Using the lower and upper quartiles as dividing points, age-length
groupings were relatively distinct, especially for younger specimens. However, older age groups overlapped
considerably in length. The oldest specimens aged were an age 12 female and an age 10 male. Maximum
lengths recorded in the Niantic River included a 490-mm female and a 483-mm male, both in 1986.
However, in May 1981, a 508-mm female determined to be age 8 was impinged on the MNPS screens.
Based on its length and age, tliis specimen fit the growth curve for the Georges Bank stock of winter
flounder described by Lux (1973).

For the purposes of calculating growth, 214 females and 188 males ranging from 44 to 465 mm were
aged by scale examination in 1983 and measuremems were made to each annulus (NUSCo 1984). A
non-linear length-scale relationship was used for the back-calculation of length-at-age because it provided
a better fit to the data. Except for ages 1 and 2, the mean calculated lengths-at-age of females were usually
larger than observed lengths (Table 13). The trend was not as obvious for males (Table 14). Calculated
growth estimates were probably less reliable for older specimens, particularly males because of small sample
size. A reverse Lee's phenomenon (Tesch 1968; Ricker 1975) was observed in which the calculated lengths
of fish increased as the age of the fish increased. This may have been the result of size-selective mortality
that was greater on the smaller fish of an age group (Tesch 1968) or due to a bias in sample selection if
only faster-growing larger specimens were used in aging and scales from slower-growing fish were rejected
as unreadable. This may also have resulted in the apparent anomalous increase in growth at age 9 in
females and 8 in males.

Growth of the Niantic River stock was compared in Figure 6 to that of other populations in nearby
areas, including Chadestown Pond, RI (Berry et al. 1965), Peconic Bay, NY (Poole 1966), and south of
Cape Cod, MA (Howe and Coates 1975). The Niantic River fish grew less tluough age 2 than these and
other populations (Poole 1966; Kurtz 1975; Danila 1978), with the exception of the nearby Mystic River
(Pearcy 1962). However, growth of Niantic River fish equaled or exceeded that of other stocks age 3 and
older. Although the winter flounder is an omnivorous feeder (Pearcy 1962; Richards 1963), conditions in
the Niantic River may not be as favorable for the growth of immature fish as other areas.

44

Table 13. Average back-calculated lengths (mm) at age for female winter flounder taken

in the Niantic River.

Mean length Mean calculated length (± 95% CI)

Age at capture ±

class Number 95% CI Age 1 Age 2 Age 3 Age 4 Age 5 Age 6 Age 7 Age 8 Age 9

30

I07±14

80±8

26

I95±13

67 + 9

178+16

43

277±11

78±7

182 + 12

285 + 12

25

3I5±13

87+10

I85H4

278 + 12

318 + 14

23

349±10

88t9

182+16

276 + 18

321 + 18

343+18

13

366±19

75+15

163 + 23

269 + 21

309+16

331 + 15

345+14

27

395±10

90+7

205+13

269+14

332+16

354+17

369+18

380+18

19

418-1:9

86+11

202 1 24

296 + 25

345 + 21

370 + 21

383 + 21

393 + 21

402 + 22

8

442 ±10

86+10

186 + 26

292 + 33

361+26

389 + 25

406 + 27

419 + 25

428 + 27

VI
VII
VIII

IX • 8 442+10 86+10 186 + 26 292 + 33 361+26 389 + 25 406 + 27 419 + 25 428 + 27 435 + 26

Mean calculated length 81+4 186 + 6 285 + 6 329+8 355 + 8 373 + 10 391 + 12 410+16 435 + 26

Average growth increment 81 105 99 44 26 18 18 19 25

Table

14.

Average back-c
flounder taken

;alculated lengths (mm)
in the Niantic River.

- at age

for male

; winter

Age
class

Number

Mean length
at capture ±
95% CI Age 1

Age 2

Age 3

Mean calculated length (± 95%
Age 4 Age 5 Age 6

Age 7

Age 8

1

28

96+13

80±8

II

18

177+16

70+13

166±I9

III

43

246+10

81+7

183+10

262+12

IV

19

285+15

75+10

171 + 19

248 + 20

281 + 21

V

26

327 + 12

92+12

181 + 18

259 + 18

301 + 16

322+16

VI

20

348 ± 1 2

84 + 9

185+17

257 + 18

302 + 1 7

322 + 17

334+18

VII

27

370+10

81+9

189 + 20

260 + 21

300 + 21

320 + 20

337+19

349+19

VIII

7

378 + 28

91 + 17

209 + 28

305 + 46

351 + 45

369 + 42

380 + 41

389 + 40

397 + 39

Mean calculated length 82 + 4 182 + 6 261+8 302 + 10 325+10 341 + 12 357+18 397 + 39

Average groivth increment 82 100 79 41 23 16 16 40

45

450-

400-

2
s

350-

300-

5

250-

X
1—
CD

■;7

200-

UJ

—I
z

150-

S

2

100-

50-

0-

MALES

4501
400
350
300
250
200
150
100
50
O-l

CC

4 5
AGE

CP

NR

"EMALES

AGE

CC

CP

NR

PR

Figure 6. Calculated mean lengths of winter flounder by age from various locations in the northeastern United States
(CC = south of Cape Cod, CP = Charlestown Pond, NR = Niantic River, PB = Peconic Bay).

46

von Bertalanffy growth model

Calculated -lengths-at-age from 1983 data were used to estimate the von Bertalanffy growth parameters
(Table 15). The growth models for females and males had good fits to the data and represented theoretical
growth of the population. Use of a nonlinear procedure for parameter estimation should have resulted in
the least biased and variable estimates in comparison with traditional linear methods used in most older
studies (Vaughan and Kanciruk 1982). The co parameter was used for comparisons of growth as suggested
by Gallucci and Quirm (1979). They suggested constructing a rectangle formed by two standard errors on
each side of point estimates of Lao and K. This was done for both sexes and because the rectangles did
not overlap, significant differences in growth were indicated between females and males. It was not possible
to make comparisons with other winter flounder populations because of the lack of published estimates
of variability. However, the co parameter of female Niantic River winter flounder was similar to those of
other stocks or geographical groups examined with the exception of Georges Bank, which has a racially
distinct population with much greater growth (Lux et al. 1970; Lux 1973; Howe and Coates 1975). The
value for males most closely corresponded to the Charlestown Pond stock (Berry et al. 1965); greater
asymptotic maximum length was achieved by winter flounder stocks in other areas to the east.

The estimates of Loo were actually less than the lengths of some specimens examined in the Niantic
River. However, this should not be considered unusual as Loo represents the maximum length that an
average fish would achieve if it grew indefmitely (Fabens 1965; Ricker 1975). This could have been a
result of the particular sample used and inclusion of additional larger and older specimens could have
increased asymptotic length estimates. Nevertheless, since 1977 lengths of only 1.7% of 14,374 females
and 1.0% of 10,706 males larger than 20 cm exceeded the calculated values.

The 1977-83 age-length data were also fit to the von Bertalanffy model (Table 15). Because sex of
age 1 and 2 and smaller age 3 fish was not ascertained in the field, these specimens were used separately
with both older females and males in fitting the model. Although growth of females and males was found
to be similar in early life, it is not known how the calculation of model parameters was affected by using
these data with each sex. Using the 1977-83 data, significantly larger estimates of Loo (453 mm for females;
397 for males) and smaller values of K (0.30; 0.34) were obtained in comparison with results using the
1983 calculated length-at-age data. Another error potentially affected results as the observed lengths were
taken over a period of several months each year and individuals could have been actually older or younger

47

Table 15. The von Bertalanffy growth parameters for Niantic River winter
flounder and comparisons with other stocks.

Ferriales

Area

No. of fish
examined

K

value

Asymptotic
95% CI

^00

(mm)

Asymptotic
95% CI

M°

to
(year)

Asymptotic
95% CI

R^

Niantic River

214

0.42

0.39-0.45

423

412-433

177.7

» 0.51

0.46-0.56

0.90

Niantic River

3789

0.30

0.29-0.31

453

446-461

135.9

-1-0.35

0.33-0.37

0.93

Niantic River

129

0.35

0.27-0.44

423

398-448

148.1

-

-

0.90

Charlestown
Pond'

104

0.41

396

162.4

--

South of Cape
Co/

839

0.34

--

487

--

165.6

--

-

--

North of Cape
Cod'

114

0.37

--

455

--

168.4

--

--

Georges Bank

126

0.44

-

622,

-

273.7

-

-

Georges Bank"

163

0.31

630

Majes

195.3

-0.05

Niantic River

188

0.44

0.39-0.48

381

367-395

165.7

-i-0.46

0.39-0.53

0.85

Niantic River

3286

0.34

0.33-0.35

397

389-405

135.0

+ 0.34

0.31-0.36

0.91

Niantic River

81

0.31

0.23-0.39

375

357-392

116.3

-

0.87

Charlestown
Pond'

49

0.54

--

323

--

174.4"

-

-

South of Cape
Cod'

298

0.25

-

477

-

119.3

--

Georges Bank

113

0.37

-

534

--

197.6

--

Georges Bank

184

0.37

550

203.5

+ 0.05

"

fo = K X Loo (Gallucci and Quinn 1979)
Fit to 1983 calculated lengths-at-age.
Tit to 1977-83 age-length data.

From method of Fabens (1965) using data from recaptured disc-tagged fish.

-k
Berry ct al. (1965); parameter K calculated from their k ( = e )

Howe and Coates (1975); parameter K calculated from their K

Lux (1973)

48

than the stated age. Conversely, error may have been introduced using the calculated lengths-at-age
because of variable timing of annulus formation. Also, if mostly faster-growing older fish were selected
for measurements of annuli on scales, as suggested previously, a larger K value may have resulted because
these specimens had a faster rate of growth.

An independent assessment of growth was obtained from winter flounder marked with Petersen disc
tags, released in the study area, and later recaptured after various periods at large. The fish used in this
analysis included females from 201 to 406 mm and males from 205 to 398 mm at time of tagging. The
recaptured fish were caught after 90 to 1,065 d at large and growth ranged from 1 to 149 mm in females
and 1 to 85 ram in males. The data were fit to a two-parameter (K and Loo) von Bertalanify model
described by Fabens (1965) for fish of unknown age, but whose increase in length is known for varying
time periods. The estimates of Loo (423 mm for females; 375 for males) were similar to those described
by the 1983 calculated length-at-age data, but the K values (0.35; 0.31) were closer to the 1977-83 aging
data model. However, less confidence can be placed on the parameters determined from the tagged fish
due to variability in the data and smaller sample size. Growth of individuals also varied because of the
particular season of release or recapture and effects of tagging may have influenced these results.

Mortality and survival

Mortality and survival were calculated using age and length data from 1978-79 and 1981-83. Data
from 1977 were not used because relatively few fish were aged and from 1980 because of previously
mentioned inconsistencies of data from that survey. Both methods of estimation used were time-specific
(Ricker 1975). Apparent large variability in estimated abundance of individuals of specific year-classes,
most likely due to changes in survey methodology, sample selection, and sampling error, made cohort-specific
methods of estimating survival less reliable or simply not possible (NUSCo 1984). The time-specific
method of Robson and Chapman (1961) has cin advantage in that the age determinations of older fish do
not have to be known with certainty, although the representativeness of the youngest age used is very
important (Ricker 1975). As noted previously, relative abundance of small winter flounder (ages 1 and 2)
in the population age structure were not accurately measured. Therefore, only ages 3 and older were used
in the calculations.

49

The geometric mean annual survival rate (S) for the five estimates was 0.572, corresponding to an
instantaneous mortality rate (Z) of 0.558 (Table 16). The value is larger than the survival estimate of
0.526 determined by Howe and Coates (1975) for winter flounder south of Cape Cod and even greater
than that for fish from Great South Bay, N.Y. (0.27-0.28; Poole 1969) and Rhode Island (0.35-0.49; Berry
et al. 1965). The estimate may be biased because of violations in required assumptions. Ricker (1975)
noted that Robson and Chapman's formula assumes that survival rate is constant at all ages, that all
year-classes are recruited at the same abundance, and that all ages are equally vulnerable to the sampling
gear. When these conditions are not met, estimates of S are biased and confidence intervals are too
narrow. Ricker also noted that differences In year-class strength are usually found for most stocks and
that the best estimate of S will be made using a catch curve with equal weighting.

Accordingly, catch curves were constructed for each year of data. Examination of the plotted log
frequencies of age showed that the curves were nonlinear. Furthermore, some bumps in the curves
increased with year, indicating probable non-uniform recruitment with stronger year-classes influencing
catches more so than average or weak ones. Tendencies for age 3 and age 7 and older frequencies to be
lower than the predicted regression line also suggested less than complete recruitment at age 3 and increasing
mortality in older age groups. Even so, for all years examined, the mean age of specimens age 3 and older
ranged only from 4.1 to 4.5. Annual estimates of Z ranged from 0.515 to 0.708, with a geometric mean
of 0.611.

Table 16. Survival (S) and instantaneous mortality rate (Z) of age 3 and older

Niantic River winter flounder determined using the method of Robson
and Chapman (1961).

Year

95% CI

1978

0.549

0.528-0.569

0.451

1979

0.564

0,539-0.589

0.436

1981

0.574

0.558-0.589

0.426

1982

0.567

0.552-0.581

0.433

1983

0.608

0.600-0.616

0.392

Geometric mean

0.572

—

0.428

0.600
0.573
0.555
0.568
0.498
0.558

Annual mortality rate = 1-S

50

Following Ricker's suggestion to combine samples from successive years, catch curves were constructed
from combined data for 1978-79 and 1981-83 (Fig. 7). Catches within each group were adjusted to give
equal weight to each year. Although years were combined, irregularities were still seen in the curves. The
geometric mean of Z for the two yearly groups was 0.721, corresponding to a survival rate of 0.486 and
an annual total mortality rate (A) of 0.514. These rates are probably less biased than the estimates made
using the method of Robson and Chapman and represent the best estimate of mortality for Niantic River
winter flounder.

Food habits

Major taxonomic groups of organisms eaten by winter flounder in the vicinity of MNPS were examined
from June 1973 through November 1974 (NUSCo 1975). Important food items consumed included
crustaceans, annelid and polychaete worms, and mollusks (Table 17). Algae was also frequently found in
stomachs at several stations, supporting the contention of Wells et al. (1973) that filamentous algae was
frequently eaten by winter flounder. This separates the winter flounder from most other northeastern
Atlantic marine fishes, which are strictly carnivorous. Average stomach fullness ranged from about
one-third full in the Niantic River to half-full at Seaside Point and Twbtree Island Channel. Food items
varied by location and seemed to reflect bottom type and different benthic communities. For example,
bivalves were particularly important in the muddier upper Niantic River, whereas worms and crustaceans
were more important in the sandier areas of the lower river and in Niantic Bay. The variable diet of
winter flounder in the area was not unexpected as it has been reported to be an omnivorous, opportunistic
feeder (Pearcy 1962; Richards 1963; Mulkana 1966; Frame 1972; Kurtz 1975; Festa 1977; Scarlett 1986).
Richards (1963) reported that winter flounder fed on more prey taxa than any other demersal fish in Long
Island Sound. Several studies have hypothesized that some movements of winter flounder are feeding
migrations not associated with water temperature preferences or for spawning (Kennedy and Steele 1971;
Van Guelpen and Davis 1979). However, not enough data were available for Niantic River winter flounder
to examine this possibility.

51

7-

1978-79

10
9

8
7

LU

m 6-

Z

^ 5-
4
3

Z = 0.793
S = 0.453
A = 0.547
r^ = 0.91

6 7

AGE

1981-83

10

AGE

Figure 7. Mortality determined by catch curve for Niantic River adult winter flounder from 1978-79 and 1981-83.

52

Movements and exploitation

Some tag return data from 1973 and 1974 studies were reported in NUSCo (1975). Anchor tags were
used in an attempt to estimate abundance and recaptures were made throughout the year during sampling
activities and by fishermen. Of 566 recaptures with location known, 422 (75%) were from local waters
in Niantic Bay and River. Most (81%) of the remainder were caught from 5 to 15 mi east of MNPS, 8
(10%) from within 5 mi to the west, 3 (4%) from 30 to 50 mi west, and 4 (5%) from offshore waters.
A large majority (80%) were caught during March through May of 1973 and 1974. Few tags were received
from cotmnercial fishermen which may be related to relatively poor retention of this type of tag in flatfish
(J. Castleman, NUSCo, pers. comm.), or to less cooperation in making returns.

Table 17.

Average estimated stomach fullness by major prey of winter flounder taken in
the Millstone Point area from June 1973 through November 1974.

Area

Upper
Niantic River

Niantic
Bay

Jordan

Cove

Seaside
Point

Twotree Island
Channel

Black
Point

Bartlett
Reef

Station bottom
type

mud

mud and
sand

sand coarse sand
and mud

sand

sand

sand and
rock

Number of fish
examined

39

48

51

32

49

49

38

Algae

3.4

1.7

Prey organisms
12.4 16.1

4.9

1.8

1.6

Sponges

-

0.1

--

0.2

1.2

2.4

Bryozoans

1.8

--

--

1.2

1.1

2.7

5.6

Mollusks

--

0.3

--

-

-

Univalves

2.6

1.6

0.4

0.2

Bivalves

14.9

4.2

1.8

2.5

15.1

9.9

7.4

Annelids

2.2

6.4

1.0

1.9

0.7

1.1

0.5

Polychaetes

4.7

6.4

14.8

14.2

5.6

10.8

8.4

Crustaceans

5.1

14.9

6.4

8.3

25.0

13.7

14.1

Oabs

0.5

2.5

0.7

4.2

0.5

1.5

Shrimp

0.7

--

0.2

0.2

Fish

--

0.3

Miscellaneous
or unidentified

0.8

2.2

2.6

1.3

1.4

2.7

2.8

Average total
points

36.7

38.7

41.5

50.1

54.7

45.7

43.0

100 = full, 50 = half full, 0 = empty

53

A study designed specifically to determine movements and exploitation by the sport and commercial
fisheries was undertaken from December 1980 through September 1983. Each of 4,978 specimens larger
than 20 cm was tagged with a Petersen disc (Table 18). Most were released in the Niantic River (46%)
and Bay (31%). About 61% were females, 29% were males, and 10% were fish whose sex was not
determined, mostly because of their smaller size.

More than half (57%) of the 1,227 recaptures were made within 6 mo of release (Table 19). Larger
percentages of fish were taken more quickly by NUSCo sampling than by the fisheries because sampling
was concentrated in the Niantic River shortly after most were released. Also, tagged fish set free in special
studies near the MNPS intakes tended to be impinged quickly, if at all. Recaptures dropped off rapidly
after 1984 with only 20 returns for 1985 and 2 in 1986. None of the latter fish were tagged in 1980 or
1981; about 40% were released in 1982 and 60% in 1983.

The overall rate of return through 1986 was 25%, with 40% of the recaptures made by sport fishermen,
33% from NUSCo sampling activities, 24% from the commercial fishery, 2% from fish impinged on the
MNPS traveling screens, and 1% from miscellaneous sources. This suggested that the sport fishery is a
significant source of mortality for the Niantic River winter flounder, also noted by Sampson (1981) and
Blake and Smith (1984). However, judging by the number of tags received from fish markets and processing
plants, cooperation by commercial fishermen in returning tags was most likely less than for sport fishermen.
The rates of return for each tagging area (ignoring NUSCo recaptures because of the disproportionate
effort in the Niantic River) were similar and ranged from 1 1 % for fish released at Bartlett Reef and the
MNPS intakes to 16-17% for Niantic River and Bay and Twotree, and 26% for .Jordan Cove.

The returns from the sport and commercial fisheries varied by location of release. The sport fishery
took about three-quarters of the recaptured fish that were released in the Niantic River and .Jordan Cove
embayments. The return from the Niantic Bay and Twotree releases was neariy equal between the two
fisheries, but about twice as many fish were caught by the commercial as the sport fishery from the deeper
water Bartlett Reef station.

Sixty-five percent of the recaptures were female, 31% were male, and 4% were fish of undetermined
sex. Similar (27%) proportions of all males and females released were caught again, but only 10% of the
undetermined fish were recaptured. It was suggested in NUSCo (1985) that because the latter fish were

54

Table 18. Summary of winter flounder disc tagging and recapture data from December

1980 through September 1986.

Niantic

Niantic

MNPS

Barlett

Jordan

Bay

River

Twotree

Intakes

Reef

Cove

Misc.

Total

Number Mgged

1980

309

410

47

0

68

10

0

844

1981

970

108

29

198

4

0

0

1,309

1982

280

1,015

294

61

206

131

10

1,997

1983

0

770

0

40

12

6

0

828

Total

1,559

2,303

370

299

290

147

10

4,978

Number
recaptured

1980

74

89

15

0

8

0

0

186

1981

179

22

3

27

0

0

0

231

1982

55

347

56

11

22

46

2

539

1983

0

264

0

4

2

1

0

271

Total

308

722

74

42

32

47

2

1,227

Method recaptured:

Sport fishing

1980

31

28

7

0

1

0

0

67

1981

64

8

0

8

0

0

0

80

1982

29

146

21

5

9

28

1

239

1983

0

105

0

0

0

0

0

105

Total

124

287

28

13

10

28

1

491

Commercial

1980

22

21

7

0

7

0

0

57

fishing

1981

91

9

3

2

0

0

0

105

1982

14

42

23

2

11

9

1

102

1983

0

27

0

0

1

0

0

28

Total

127

99

33

4

19

9

1

292

NUSCo

1980

18

38

1

0

0 "

0

0

57

sampling

1981

21

5

0

7

0

0

0

33

1982

12

155

9

1

0

8

0

185

1983

0

129

0

2

1

1

0

133

Total

51

327

10

10

1

9

0

408

Impingement

1980

1

2

0

0

0

0

0

3

at MNPS

1981

0

0

0

10

0

0

0

10

1982

0

3

0

3

1

1

0

8

1983

0

3

0

2

0

0

0

5

Total

1

8

0

15

1

1

0

26

Miscellaneous

1980

2

0

0

0

0

0

0

2

1981

3

0

0

0

0

0

0

3

1982

0

1

3

0

1

0

0

5

1983

0

0

0

0

0

0

0

0

Total

5

1

3

0

1

0

0

10

Includes various locations along shoreline west of Black Point to the Connecticut River.

Year here and following refers to year in which fish were tagged. Number recaptured includes

.390 released alive (mostly hy NU.SCo), 86 of which were caught again once, 5 twice, and 1 three

times.

Includes recaptures from the CT DEP, Project Oceanology, and unknown sources.

55

smaller at time of tagging than most of the fish sexed, they may have had greater initial mortality following
tagging, shed tags at a greater rate than larger fish, or were less vulnerable to capture. Many of them were
probably smaller females since their movements tended to be similar to that of mature females. Propor-
tionately, more females smd fish of undetermined sex were taken from distant locations than males. Since
even small males were readily sexed during the spawning season, it is likely that most of them were
identified when tagged.

Table 19.

Months

: at liberty

for disc-tagged winter flounder

by method of

recapture.

Months

Sport

Commercial

NUSCo

Impingement

Percent

at liberty

fishiriR

fishinR

sampling

at MNPS

Miscellaneous"

Total

of total

0-3

172

67

213

20

6

478

39

4-6

86

80

47

4

2

219

18

7-12

102

55

91

2

1

251

20

13-18

74

46

21

0

1

142

12

. 19-24

37

33

28

0

0

98

8

25-40

19

11

8

0

0

38

3

Total

490"

292

408

26

10

1,226

* Includes recaptures from the CT DEP, Project Oceanology, and unknown sources.
Month of one recapture not known.

Most (70%) of the returns were from waters near MNPS (Table 20). Similar to the 1973-74 study,
movement out of the area tended to be to the east as about three times as many recaptures occurred there
in comparison to the west. Most fish were taken in Fishers Island and Block Island Sounds, but 23 winter
flounder were taken in waters near Martha's Vineyard and on Nantucket Shoals. One fish was caught off
Cape Cod in February 1983 and in February 1985 one specimen was caught on Georges Bank. This
specimen plus the very large 8-yr old mentioned above indicated that a very small interchange may occur
between inshore and offshore stocks. Howe and Coates (1975) reported that a few percent of the winter
flounder they tagged in inshore waters of southern Massachusetts were recaptured on Georges Bank and
vice versa. Georges Bank winter flounder are usually recognized as a distinct race (Perlmutter 1947; Lux
et al. 1970).

56

Table 20. Location of recaptures of disc -tagged winter flounder from December 1980 through

September 1986.

Recapture location

Tagging location

liantic

Niantic

Twotree MNPS

Bartlett

Jordan

Miscellaneous

Bay

River

Intakes

Reef

Cove

Niantic Bay
Niantic River
Twotree
MNPS Intakes
Bartlett Reef
Jordan Cove

127

60

37

495

2

1

8

222
543

New London Co., CT

43

35

Suffolk Co., NY

6

17

Washington Co, RI

35

37

Newport Co., RI

1

Barnstable Co., MA

1

Dukes Co., MA

4

3

Nantucket Co., MA

3

7

Georges Bank

1

New London Co., CT

10

5

Middlesex Co., CT

4

11

Suffolk Co., NY

10

6

New Haven, Co., CT

7

2

Fairfield Co., NY

2

I

Bronx Co., NY

-■

--

Unknown

Connecticut

I

I

New York

I

Rhode Island

4

7

Massachusetts

5

7

Virginia'

1

32 47

Mostly from fish markets.

Most likely caught in Rhode Island.

57

In general, Niantic River and Bay winter flounder showed patterns of movement similar to those
reported by others. Lobell (1939) noted that concentrations of winter flounder near Block Island in
summer were fish from the Long Island region. Weber and Zawacki (1986) tagged and released winter
flounder in two bays off western Long Island Sound, New York. Most of the recaptures were made
locally and many of the distant returns were from areas to the east during summer and fall. However,
less than 10% of the recaptures were made outside of Long Island Sound. The majority of the fish seemed
to return to areas around the tagging site in subsequent years. Danila and Kermish (1981) and Scarlett
(1986) reported that fish resident in central and northern New Jersey estuaries from fall through spring
moved offshore and to the north and east for surmiier. Howe and Coates (1975) found that winter
flounder south of Cape Cod tended to move offshore to the southeast when water temperatures exceeded
15 °C. The Niantic River winter flounder population appears to have some individuals that remain in
local waters throughout the year, yet others are able to move relatively long distances and successfully
return each winter before spawning.

Stock identification

The ability to identify and separate stocks is important when quantifying impacts. If more than one
discrete population is affected, then losses may be partitioned accordingly. A study was undertaken for
NUEL by the University of Rhode Island in 1980-81 to investigate techniques for differentiating winter
flounder stocks using a specific biochemical technique (Schenck and Saila 1982). The method chosen was
direct tissue isoelectric focusing of eye lens proteins. Briefly, when a constant electrical potential is applied
to a pH gradient formed within a gel, each of the separate proteins migrates to its isoelectric point, where
it has no net electrical charge. This allows for the differentiation of even closely related protein molecules
and provides a criterion of genetic homogeneity. A brief summary of the study follows.

The first portion of the work in 1980 examined fish taken from major estuaries or embayments over
a relatively large (125 km) geographical area. Fish collected from New Haven, the Connecticut River, the
Niantic area, Thames River, Mystic River, and Charlestown Pond separated well when the data concerning
the presence or absence of certain proteins were used with linear discriminant analysis. Classification of
individual winter flounder was highest in the correct area of capture with misclassification tailing off as a
function of geographical distance from the source of each fish.

58

The 1981 study focused on a much smaller geographical area (23 km) using fish from the Connecticut
River, Niantic River, Niantic Bay, Jordan Cove, and the Thames River. These areas were thought to be
likely sources of winter flounder affected by MNPS operations. Because of the smaller area in which fish
were taken, the samples were much more homogeneous than the ones in 1980. Fish from Jordan Cove
often misclassLfied into Niantic River or Bay or the Thames River. The Connecticut River winter flounder
also misclassified frequently. Upon further examination, most of the latter fish were found to have been
sexually immature, which was thought to have caused the failures in discrimination. The seasonal samples
taken in Niantic Bay over the year showed substantial variability; summer and fall samples were not
significantly different, but other seasons were.

The major conclusion of the study was that the technique was able to distinguish between stocks or
subpopulations of winter flounder found about 5 to 10 km apart. Winter flounder in the area around
MNPS appeared to form separate stocks only during the winter and spring spawning season, with inter-
mixing greatest during summer and fall. The areas immediately in the vicinity of the plant (Niantic River
and Bay and Jordan Cove) appeared to be inhabited by substocks that intermix significantly. Additional
interchange took place with stocks from more distant areas, such as the Connecticut and Thames Rivers.
Immature fish were impossible to classify using the techniques and analyses employed during the study.
They were a heterogeneous group either because they were well-mixed over the geographical range of the
study or because juveniles showed a lack of differentiation for the particular proteins examined. As
young-of-the-year fish were not examined, this conclusion may not apply to them.

The fmdings of this study along with tagging data indicated that at certain times of the year the winter
flounder impinged at MNPS as well as throughout the study area were a mixture of a number of different
spawning stocks. Consequently, the long-term effects of this particular impact on the Niantic River stock
are somewhat reduced because of the dilution. Furthermore, the degree of intermixing implies that
interchanges frequently occur among local stocks; this would also help to mitigate losses particular to any
one of them.

59

Larval studies

Several special studies and analyses have been conducted to identify possible sampling biases in the
larval winter flounder data base. Because of the biases there are limitations in the usefulness of some of
the data. Therefore, the results of these special studies are presented fu-st to identify these limitations.

Net extrusion studies

The effects of mesh size and tow duration on the sample density of larval winter flounder were
examined in the field and laboratory. Field comparisons of the collection of 1-mm size-classes were made
for 333 and 505-^m mesh nets from the 1974 and 1975 data (Fig. 8). Based on paired comparisons, the

9001
800
7001
600
500
400
300
200
100
0

333 505 333 505 333 505 333 505 333 505 333 505

3 4 5 6 7 8

LENGTH (MM)

Figure 8. Compari.son of larval winter flounder length frequencies by 1-mm size-class collected in paired 333- and
505-tim mesh nets during 1974 and 1975.

60

333-}im mesh collected significantly greater densities of the 3- and 4-mm size-classes with no differences
detected for the other size classes. The effect of mesh size (202- and 333-jim) and tow duration (6- and
15-min) on net extrusion of early developmental stages (Stage 1 and 2) was examined in 1984 during
February and March (NUSCo 1985). In the comparison between the two mesh sizes, Stage 1 larvae were
collected in greater densities with 202-|im mesh in 21 of 28 paired comparisons, which represented a
significant difference. No difference was found for Stage 2 larvae, with their density in the 202-nm mesh
greater in only 1 3 of the 28 comparisons. No difference in the collection density of Stage 1 and 2 larvae
was found between the 6- and 15-min tow durations (16 comparisons). The results of laboratory com-
parisons of 202- 333-, and 505-nm mesh (NUSCo 1986a) verified the fmdings of the field studies with the
greatest retention in 202 \im (92%), followed by 333 jim (78%), and 505 ^m (63%).

Prior to 1984, all ichthyoplankton sampling at MNPS was conducted with 333- or 505-|im mesh nets
and during this period the early developmental stages were probably undersampled. This undersampling
limited the use of these data to examine the abundance and distribution of early developmental stages.
Although only a 333-tim mesh net was used for all recent entrainment collections, it probably did not
result in underestimates because 202-^m mesh nets were used at station NB during 1985 and very few
Stage 1 larvae were found in Niantic Bay (NUSCo 1986a).

Die! behavior

Diel behavior patterns of larval winter flounder could affect sample densities and bias abundance
estimates. A comparison of day and night collections was made at three stations where balanced day and
night sampling was conducted during several years: EN from 1976-85, NB from 1979-85, and C from
1980-83. The percentages that each 1-mm size-class made up of day and night samples were examined
(Fig. 9). At stations EN and NB an increasing percentage of the 5- to 6-mm and larger size-classes
occurred in night collections. Although the 5-mm and larger size-classes were more prevalent in night
samples at station C in the Niantic River, the difference was less apparent than found at the other two
stations. Comparison of day and night collections by developmental stage was possible with 1983 data
(Fig. 10). Only in this year were all three Niantic River stations (A, B, and C) sampled during both day
and night throughout the season. Stage 4 larvae at station A and Stage 1 larvae at stations EN and NB
were excluded because of low collection densities. No consistent difference between day and night

61

EN 1976-1985

90
80
70
60
50
40
30
20
10
0

90

80
70
60
50
40
30
20
10
0

D N
3

D N
3

D N
4

D N D N

5 6

LENGTH (MM)

NB 1979-1985

D N
4

D N D N

5 6

LENGTH (MM)

D N

7

D N
7

Figure 9. Comparison of the percentage of larval winter flounder Ukem in day (D) and night (N) collecdons by 1 mm
size-class at stations EN, NB, and C during various time periods.

62

C 1980-1983

70
60

501

UJ

^ 40

I—

LJ
O

°^ 30 "

Q.

20
10

D N
Figure 9. cont. 3

100
90
80
70
60
50
40
301
20
10
0

DN DN DN DN DN

4 5 6 7 8

LENGTH (MM)

1234 1234 1234 1234 1234

DAY

NIGHT

Figure 10. Comparison of the percentage of larval winter flounder taken in day and night collections by
developmental stage at each station in 1983.

63

collections were found for Stage 1 and 2. For Stages 3 and 4, percentages were noticeably higher during
the night at stations B, NB, and EN, but not at C. These diel differences have been attributed to vertical
movement of larvae from on or near bottom into the water column at night (NUSCo 1984). This behavior
pattern appears during Stage 3 following development of fm rays. The predominant length range of Stage
3 larvae is 5.0 to 7.5 mm (NUSCo 1984, 1985, 1986a) and the behavior pattern found for Stage 3 and 4
larvae agreed with the results based on size-classes. The lack of diel vertical movement of Stage 3 and 4
larvae at station C suggested that other factors in the lower river, such as tidal currents must have affected
their behavior.

Comparison of day and night collections showed that abundance estimates based on daylight collections
could underestimate the abundance of 5 mm and larger larvae. This was the reason for reducing sampling
in the Niantic River to only night during May and June starting in 1984. Entrainment sampling remained
balanced between day and night for the estimation of entrainment. Sampling at station NB remained
balanced because this station was also used to monitor other species. The daylight sampling bias severely
limited the usefulness of earlier data in examining the abundance and distribution of larval winter flounder.
In 1974 and 1975, collections were only made at night once a month andlTrom 1976-78 and none were
made during the larval winter flounder season. In addition, the special- larval winter flounder sampling in
the Niantic River during 1979 consisted of only daylight collections.

24-h studies

Sampling was conducted over 24-h periods at station C to examine the effect of tidal stage on the
sample density of larval winter flounder (Fig. 11). Two studies in 1983 occurred when the predominant
developmental stages were 3 (62%) and 4 (30%). During 1984, when two additional studies were
conducted. Stage 1 (48%) and 2 (51%) dominated. There was an apparent tidal effect on sample densities
in both studies in 1983 and the March 19 study in 1984. Harmonic regression was used with log-transformed
data to relate changes in density to tidal stage for these three studies (NUSCo 1984, 1985). A 12-h tidal
period was used with slack low at hours 0, 12, and 24 and slack high at hours 6 and 18. Satisfactory
fits were achieved for Stage 1 larvae (/?^ = 0.58) in the March 19, 1984 study and the combination of Stage
3 and 4 larvae on both sampling dates (R^ = 0.45) in 1983. Analysis of covariance of the 1983 studies
(NUSCo 1984), with tidal effect as described by the harmonic regression as the covariate, showed

64

APRIL 28, 1983

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

j EBB I FLOOD | EBB , FLOOD,

TIME (H)
MAY 9, 1983

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
, EBB , FLOOD , EBB i FLOOD ,

TIME (H)

Figure 11. Larval winter flounder densities per 500 m for 24-h studies at station C in 1983 and 1984 with time of
collection and tidal stage.

65

800

700

600

(1 500

Q 400

300

200

100-1-

MARCH 12,1984

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

I FLOOD I EBB , FLOOD , EBB ,

TIME (H)

MARCH 19,1984

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

I EBB I FLOOD , EBB | FLOOD ,

TIME (H)

Figure 1 1 . cont.

66

that an additional 19% of the total corrected sum of squares was due to the difference between the two
sampling dates (April 28 and May 9). Based on the harmonic regressions, the effect of tidal stage on
sample density at station C was inverse for Stage 1 compared to Stage 3 and 4 larvae (Fig. 12). Stage 1
density increased during ebb tides and declined during flood tides. This pattern was attributed to the
flushing of Stage 1 larvae from the upper portion of the Niantic River, where they were more abundant,
into the lower portion during ebb tide (NUSCo 1985). The decline during flood tide was caused by water
from Niantic Bay that contained few Stage 1 larvae entering the river. The inverse relationship for Stage
3 and 4 larvae was attributed to vertical migration in response to tidal flow as a retention mechanism
(NUSCo 1984), where the larvae remained on or near the bottom during an ebb tide and moved up in
the water column during flood tides. This tidal behavior of Stage 3 and 4 larvae would help explain the
lack of diel behavior at station C, as shown above (Fig. 10).

6-

A\

STAGE 3 AND 4

0 2 4

, FLOOD

8 10 12 14 16 1i
EBB I FLOOD ,

20 22 24 26
EBB I

HOUR

Figure 1 2. Harmonic regression models of larval winter flounder abundance (log density per 500 m ) during 24-h
tidal cycles at station C for developmental Stage 1 and Stage 3 and 4 combined.

67

Due to the effect of tides on sample density, starting in 1984 sampling time was based on tidal stage.
During the occurrence of Stage 1 larvae sampling was conducted close to low slack and when Stage 3 and
4 larvae were common sampling was conducted during the latter portion of a flood tide. Prior to 1984,
larval abundance in the lower portion of the Niantic River may have been underestimated, as sampling
was not synchronized with tidal stage.

Abundance and distribution

The distribution of larval winter flounder near MNPS was examined based on the area-wide sampling
conducted during 1974 and 1975, when up to 16 stations were sampled (Fig. 3). To reduce sampling bias
the data were restricted to oblique samples collected with 333-(im mesh nets. The date of peak abundance
was estimated from the point of inflection (Equation 8) of the Gompertz function to compare the temporal
distribution in six areas. The grouping of stations resulted in 2 to 9 samples per week in 1974 and 2 to
15 samples per week in 1975 for calculating a weekly mean used to construct the cumulative density curve
for the Gompertz function. Assuming that the Niantic River was the primary source of winter flounder
larvae in the area, the progressive date of peak abundance would provide a relative measure of dispersal
rate from the Niantic River. All fits of the Gompertz function exceeded an R} value of 0.97. A similar
pattern of the time of peak abundance was found for both years (Table 21). As expected, the earliest

Table 21. Estimated date of peak abundance for larval winter flGunder based on the

inflection point of the Gompertz function for six areas around Millstone
Point in 1974 and 1975.

Area

Niantic River

Mouth of the Niantic River

Mid-Niantic Bay

.Jordan Cove

Twotree Channel

onshore

19 7 4

19 7 5

27 Feb

30 Mar

4 Apr

7 Apr

10 Apr

13 Apr

13 Mar

29 Mar

3 Apr

15 Apr

16 Apr

17 Apr

68

peak was in the spawning area of the Niantic River. The date of peak abundance progressed to the mouth
of the Niantic River, mid-Niantic Bay, and then throughout the Millstone area. It took from 21 d in
1975 to 36 d in 1974 for the peak to progress from the Niantic River to mid-Niantic Bay, but once in
the bay dispersal was rapid to other areas. This progressive pattern of peak abundance as a relative
measure of dispersal rate agreed with the findings of the larval dispersal model (Saila 1976). The Niantic
River has high larval retention characteristics, but once larvae enter Niantic Bay they spread throughout
the area.

A more detailed examination of the abundance and distribution of larval winter flounder in the Niantic
River and Bay was possible with the data collected from 1981 through 1985. Abundance curves (Equation
7) were constructed from the Gompertz function (all R^ values of the Gompertz function exceeded 0.95)
for each year in the Niantic River (stations 1 and 2 combined for 1981 and 1982; A, B, and C for 1983
through 1985) and Niantic Bay (stations NB and EN combined). If collected, daylight samples during
May and .lune were excluded because they would have underestimated larval abundance during this period.
Larvae were most abundant in the river during 1982 and 1985 and the time of peak abundance for all
years occurred during mid to the latter part of March (Fig. 13). In the bay, larvae were most abundant
in 1982 and 1983, with similar numbers during the remaining 3 yr. The timing of peak abundance varied
more than for the river, ranging from about the second week of April in 1985 to the fu'st week of May
in 1981. Except for 1982, there was no apparent relationship between annual abundance in the river and
bay. For example, in 1985 larvae were most abundant in the river but were not abundant in the bay,
and in 1983 larvae were most abundant in the bay but were not abundant in the river.

The abundance of each developmental stage was compared in the Niantic River and Bay from 1 983
through 1985, the only years that larvae were classified in developmental stages. The a parmeter from the
Gompertz function (Equation 6) was used as an index of abundance. This function fitted the data well
with all R^ values exceeding 0.97 and the 95% asymptotic confidence intervals for the a parameter were
small (Table 22). However, less than 20 observations were used and the actual intervals may be larger
because asymptotic theory generally requires large data sets to apply. The most noticeable difference in
the river was the high abundance of Stage 1 and 2 larvae in 1985 compared to the previous 2 yr. This
occurred despite decreasing estimates of egg production from 1983 through 1985 (Table 11). The low
abundance of Stage 1 and possibly early Stage 2 larvae in 1983 was partly attributed to net extrusion
through the 333-nm mesh nets (NUSCo 1985). The previously discussed high densities of larvae in 1985

69

4000

3000

2000

1000

RIVER

1985

5FEB 28FEB 20MAR 09APR 29APR 19MAY 08JUN 28.JUN

DA^E

800
700 i
600

500-

400-

300

200

100

BAY

1985

1983

!8FEB 20MAR 09APR

29APR
DATE

19MAY 08JUN 28JUN

Figure 13. Estimated abundance curves (number/500 m ) for larval winter flounder at Niantic River and Bay stations
from 1981 through 1985.

70

in the river (Fig. 13) was a result of Stage 1 and 2 larval densities. In the river, densities of Stage 3 larvae
were similar in 1983 and 1985, but both were lower than in 1984. The higher abundance of Stage 2 and
the lower abundance of Stage 3 larvae in 1985 compared to 1984 indicated higher mortality during Stage
2 to Stage 3 development in 1985. The Gompertz function was not fitted to Stage 1 larvae in the bay
because they were rarely collected there. Stage 2 abundance in the bay for 1984 and 1985 was much lower
than in the river; this was expected because it is during this developmental stage that the larvae are tidally
flushed from the river (NUSCo 1985). The low abundance of Stage 2 in the river compared to the bay
in 1983 may be due to undersampling of early Stage 2 larvae in river because of net extrusion. The large
decrease in abundance from Stage 3 to Stage 4 in the river and bay during all years was not completely
attributed to mortality, but probably represented an undersampling of the older larvae. At Stage 4 of
development, the left eye has migrated to or past the mid-line, the larvae become more demersal, and not
as susceptible to capture with a plankton net. The undersampling of Stage 4 larvae should have remained
constant from year to year; therefore, their decreasing frequency in the river and bay since 1983 probably
represented a decrease in abundance.

Table 22. Larval winter flounder abundances and 95% asymptotic confidence

intervals as estimated by the a parameter fi-oni the cumulative Gompertz
function.

Developmental

stage

1983

1984

1985

Niantic River

1
2
3
4

540 (509-570)
1350 (1317-1383)
1029(1007-1051)

306 (263-331)

4075 (3727-4424)

2948 (2646-3250)

1846(1667-2024)

270 (228-312)

Niantic Bay

7836 (7641-8031)

5783 (5621-5947)

1023 (965-1082)

162(125-199)

2
3
4

1368 (1320-1417)

2045(1991-2099)

620 (581-657)

994(961-1027)

1326(1272-1379)

355 (306-405)

944 (906-983)

1172 (111-1232)

127 (116-139)

71

The temporal occurrence of each developmental stage in the river and bay from 1983 through 1985
was compared using the dates of peak estimated abundance (Table 23). These dates were estimated from
the inflection point (Equation 8) of the same Gompertz function that was used to estimate the a parameter
above. Since 1983, the dates of peak larval abundance have been very similar for Stage 1 in the river and
Stage 2 in the river and bay. The lag in peak abundance of Stage 2 in the bay compared to the river
ranged from 17 to 23 d. This difference between the river and bay may be related to flushing rate because
the average retention time of a passive particle in the Niantic River was reported as 25 d by Moore and
Marshall (1967) and 27 d by Kollmeyer (1972). Within each year, the dates of peak abundance for Stage
3 were similar in the river and bay. The greatest difference in dates among years was for Stage 4 larvae,
which in 1983 peaked earlier than either 1984 or 1985. The similarity in the estimated dates of peak
abundance, particularly Stage 1 larvae in the river, indicated that peak spawning occurred approximately
at the same time during the 3-yr period. Based on water temperatures of 2 to 3 °C during the latter
portion of February and egg incubation times reported by Buckley (1982), peak spawning probably
occurred in mid-February. The lack of Stage 1 larvae in the bay showed that spawning took place almost
exclusively in the river and the lag in Stage 2 abundance represented the gradual flushing of larvae from
the river to the bay. The similarity in the date of peak abundance for Stage 3 larvae between the the river
and the bay in each year indicated that by this stage of development the dispersion of larvae from the
river to the bay was completed.

Table 23. Estimated date of peak abundance oflarval winter flounder in the Niantic

River and Bay from 1983 through 1986.

River

Bay

Developmental

1983

1984

1985

1983

1984

1985

stage

1

5 Mar

9 Mar

11 Mar

2

16 Mar

18 Mar

16 Mar

8 Apr

9 Apr

2 Apr

3

18 Apr

26 Apr

25 Apr

23 Apr

30 Apr

24 Apr

4

30 Apr

19 May

17 May

10 May

23 May

18 May

72

A comparison of the spatial distribution of each developmental stage in 1983 through 1985 was based
on the cumulative abundance of weekly mean densities at each station (Fig. 14). As previously stated,
Stage 1 larvae were collected almost exclusively in the river and their low abundance in 1983 compared
to Stage 2 larvae was the reason for conducting net extrusion studies in 1984 and 1985. Their annual
spatial distribution varied with the greatest numbers collected at stations B and C in 1984 and at station
A in 1985. A similar pattern was found for Stage 2 larvae in 1984 and 1985. The previously mentioned
high mortality from Stage 2 or 3 in 1985 was apparent at all river stations. Stage 3 and 4 larvae were
primarily collected in the lower portion of the river at C and at Niantic Bay stations, but rarely at A. The
decline in larval abundance since 1983 in the bay (Fig. 13) was reflected in decreasing frequency of Stage
3 and 4 larvae at EN and NB. The decline in Stage 4 larvae in the river and bay (Table 22) from 1983
through 1985 was evident at stations B, C, EN, and NB.

Time-based harmonic regression models were used to describe the fluctuations in abundance of larval
winter flounder at station EN (1976-85) and NB (1979-85). Both models had a seasonal component and
1-yr and 6-mo terms (Table 24). It was possible to correct for autocorrelation at station EN because the
data were evenly spaced in time. No long-term trends were present in either model. The models fitted
the data well with R^ values of 0.93 for EN and 0.91 for NB. The time-based models will be used as
base-line information on the abundance of larval winter flounder for a comparison to their abundance
during Unit 3 operation.

Table 24. Summary of time-based regression models to describe the occurrence of
larval winter flounder at stations EN and NB.

Station Model^ Model R^

i

EN s {sin(l r) - cos(l K) - sin(6m) - cos(6wi)} -\- A/ + A2 - A3 - A8 0-93

NB s {sin(l r) - cos(l r) - sm{6m) - cos(6m)} 0-9 1

S = Season

nY, nM = period in years or months

An = autoregression coefficients

73

STAGE 1

10000

9000

8000

I 7000
u

uj 6000
>

^ 5000

1 4000
a

3000

2000-

1000

0

M

twsrt.'j CT^^^^^i

83 84 85 83 84 85

83 34 85
STATION
STAGE 2

83 84 85
I— EN — ^

83 84 85
I— NB — I

8000-
7000-

on
7

6000-

LU

a
u
>

5000-

^

4000-

3

O

3000-

2000-

1 000 -

^

83 34 85

83 84 85

83 84 85
STATION

53 84 85
1— EN — I

83 84 85
h— NB — !

Figure 14. Cumulative density by developmental stage for larval winter flounder at each station from 1983 through 1985.

74

STAGE 3

4000

^ 3000

>

§ 2000

1000

i:^^^ m.

m

m

m w^smm m

83 84 85 83

84 85

83 84 85
STATION
STAGE 4

83 84 85
^ EN — ^

83 84 85
^ NB — I

800

700-

^ 600-

m

-z.

LJ

Q 500

Ld
>

§ 400

g 300

200
100

0

V^ gggg^ F^?31

.^

83 84 85 83

83 84 85 83 84 85 83 84 85

I C 1 h- EN— 1 I— NB— I

STATION

Figure 14. cont.

75

The abundance and distribution of larval winter flounder in the Niantic River could be affected by
predation. During their occurrence, the medusal stage of the lion's mane jellyfish {Cyanea sp.) was
examined as a potential predator (Miller et al. 1986). Larval predation by these medusae has been observed
in laboratory studies at NUEL. A medusa was placed in a container with laboratory-reared Stage 2 larvae.
All larvae that came in contact with a tentacle were immediately stunned and even larvae that were not
consumed by the medusa sank to the bottom and died. During the larval winter flounder season an
examination of medusae in the Niantic River showed that up to 50% of the feeding jellyfish had fish
larvae in their gastrovascular cavity. Medusae were primarily collected in the upper portion of the river
at station A. Marshall and Hicks (1962) also found that jellyfish were most abundant in the upper river.
During the 3-yr period there were noticeable differences in the abundance of medusae at station A (Fig,
15). Fewest were found in 1985, which corresponded to highest larval densities (Fig. 14).

401

30

In 20

10

1984

— 1985

15FEB 01 MAR 15MAR 29MAR 12APR 26APR 1 0MAY 24MAY

DATE

Figure 1 5. Weekly mean volume (liters/500 m ) of Cyanea sp. medusae collected at station A in the Niantic River
from 1983 through 1985.

76

Weekly densities of medusae at station A were estimated by comparing the volumes of medusae in a tow
to the mean weekly medusoid bell diameter, using a medusoid diameter-to-volume relationship (Fig. 16).
Density estimates in 1983 and 1984 reached a maximum of approximately 3 to 4 per m but during 1985
never exceeded 1 per m (Fig. 17). Considering the high jellyfish densities in 1983 and 1984 and with
tentacles extending up to 10 to 15 cm below the bell, there was a relatively high probability that a larvae
would come into contact with a medusa.

501

40

30

O 20

10

V0LUME=7.61822 - 0.45019 DIAMETER + 0.00867 DIAMETER
R =0.88 N=63

20 30 40 50 60 70

DIAMETER (MM)

80

90

100

Figure 16. Polynomial regression of individual Cyanea sp. medusoid diameter to volume.

There are numerous accounts that jellyfish are predators offish larvae. Several species of hydromedusae
and the scyphomedusa Aurelia aurita were found to prey upon herring larvae (Clupea harengus) (Arai and
Hay 1982; Moller 1984). Laboratory studies with cod {Gadus morhud), plaice {Pleuronectes platessa), and
herring showed that the capture success by A. aurelia increased with medusa size (Bailey and Batty 1984).

77

Evidence of a causal predator-prey relationship on larvae of two European flatfish {Pleuronectes platessa
and Platichthys flesus) by A . aurita and the ctenophore Pleurobrachia pileus was reported by van der Veer
(1985). Pearcy (1962) stated that Sarsia tubulosa medusae were important predators of larval winter
flounder in the Mystic River, CT, and had greatest impact on younger, less motile individuals. Crawford
and Carey (1985) reported large numbers of the moon jelly (A. aurata) in Point Judith Pond, RI and felt
that they were a significant predator of the pelagic larval stage of winter flounder. Although no causal
predator-prey relationship in the Niantic River was established, there was strong circumstantial evidence
that the lion's mane jellyfish was an important source of mortality for winter flounder larvae.

1984-

1983-

15FEB 01 MAR 15MAR 29 MAR 12APR 26APR 1 0MAY 24MAY

DATE

Figure 1 7. Estimated abundance (number /m ) of Cyanea sp. medusae based on the volume to mean diameter
relationship.

78

Age and growth

Otoliths from larval winter flounder were examined to determine if an age-length key could be
constructed as deposition of daily increments on otoliths has been reported for many fish (e.g., Pancila
1971, 1974; Brothers et al. 1976; Laroche et al. 1982; Campana and Neilson 1985). Radtke and Soberer
(1981) reported that winter flounder larvae deposited a daily increment on otoliths following yolk absorption .
In 1984, otoliths from 104 larvae collected in the Niantic River were examined and 81 of these were
sufficiently clear to count the number of increments. Total increment counts ranged from 0 to 1 for Stage
1, 0 to 6 for Stage 2, 5 to 35 for Stage 3, and 17 to 50 for Stage 4 (Fig. 18). Based on the low counts
for Stage 2 and older larvae, daily increment deposition was not apparent. The otoliths of known-age

100

60

30

20

10

6

3

2

0-1

4 4+ 1 '^,

4

34
3

3
3 3

2 2 2 3

2 2 2

2 2

2

1 21
1111. 1 2_

5 6 7

LENGTH (MM)

Figure 18. Otolith increment count by length for each developmental stage oflarval winter flounder from 1984
samples.

79

larvae reared in the laboratory in 1985 were examined to determine if daily increments were formed (Table
25). Increment formation did not start until after yolk absorption, which agreed with the fmdings of
Radtke and Scherer (1981). But contrary to their fmdings, daily increment deposition was not evident
when otoliths were examined with a light microscope using transmitted light. A comparison of the number
of increments on known-age laboratory-reared larvae by length agreed well with increment counts from
the 1984 field data. Campana and Neilson (1985) stated that daily deposition may occur, but due to the
resolution limit of a light microscope individual increments caimot be seen. Ongoing research at the
University of Rhode Island (Dr. A. Durbin, University of Rhode Island, Narragansett, Rl, pers. comm.)
has shown that daily increments on winter flounder otoliths were not discernible using a microscope with
transmitted light, but increment defmition could be enhanced with special grinding, polishing, coating, and
reflected light techniques.

Table 25. Number of visible otolith increments from known age laboratory-reared
larvae with the number and length range of individuals examined.

Age
(days from hatching)

Increments

Number
examined

Length
range (mm)

7

0

3

3.6 - 3.7 .

11

0 - 2

3

3.8 - 4.4

21

3

1

4.5

. 28

2- 3

2

5.0 - 5.8

35

3

3

5.1 r 6.1

42

4- 5

3

5.8 - 6.9

49

6

1

7:2

56

7

2

6.6 - 7.8

70

30 - 32

3

6.3 - 7.1

The laboratory-reared larvae in 1985 were also used to examine developmental time and the effects
of starvation on growth and development. The larvae were held in three aquaria and those in one were
not fed. Water temperature ranged from 4.3 to 9.1 °C with a gradual increase occurring during the holding
period. Mean length at hatching was 2.94 mm (SE= 0.017; n= 160). Yolk absorption occurred 10 d after

80

hatching and growth was similar in both fed and unfed treatments (Fig. 19). By 18 d after hatch most
larvae in the unfed treatment were dead. Buckley (1980) reported 100% mortality at 6 to 9 d after yolk
absorption for unfed laboratory-reared winter flounder larvae. From laboratory information it appeared
that if no food was available within 8 d following yolk absorption, high mortality would occur. The
starvation period may be even shorter due to the "point of no return" reported by Blaxter and Hempel
(1963) and discussed by May (1974), as a starved larva will become too weak to feed and survive even if
food is provided.

In the laboratory, the duration of Stage 1 was 10 d, Stage 2 was 32 d. Stage 3 was 14 to 28 d, and
Stage 4 was less than 14 d. The estimates of Stage 3 and 4 were ranges because the sampling of larvae
occurred at 2-wk intervals due to low abundance. These developmental periods were within the range of
estimates for Stage 1, 2, and 3 larvae from the 1983-85 field data (Table 26). The developmental times
from the field data were estimated by modal progression (NUSCo 1985) using the number of days between
peak abundance of successive developmental stages. However, Hairston and Twombly (1985) demonstrated
that changes in mortality rates could bias estimates of developmental time based on modal progression.
Until the effects of mortality on the use of modal progression are determined, these estimates of develop-
mental time from field data are of questionable validity.

Table 26. Estimated development time (days) for larval winter flounder Stages 1 to
3 based on modal progression for 1983 through 1985 from Niantic River
collections.

Developmental
stage

1983

1984

1985

1

2

3

Total

11

32
12
55

9

39
23
71

5

40
22
67

81

FED

20 30 40

DAYS FROM HATCHING

Figure 1 9. Mean length and range of laboratory-reared fed and unfed winter flounder larvae.

82

Examination of the length -frequency distribution of larvae collected from 1983 through 1985 showed
a separation between the first three developmental stages by predominant 0.5-mm size-classes (Fig. 20).
Stage 1 larvae were primarily in the 2.5 to 3.0 size-classes (84%), Stage 2 were 3.0 to 4.5 (88%), Stage 3
were 5.0 to 7.5 (87%), and Stage 4 were 6.5 to 8.0 (83%). These predominant size-classes for each
developmental stage were similar in each of the years (NUSCo 1984, 1985, 1986a), indicating that stage
development and length were closely related. Due to this relationship, larval developmental stages can be
estimated from length measurements for data collected prior to larval classification by stage in 1983.

A comparison was made of the length-frequency distribution of larvae collected in the Niantic River
and Bay during 1981-85 (Fig. 21). Like the spatial distribution of developmental stages (Fig. 14), smaller
larvae dominated in the river and larger larvae in the bay. The 3.0-mm and smaller size-classes comprised
over 50% of the larvae collected in the river during the 5-yr period, even though the collections in 3 of
the 5 yr were made with 333-|im mesh nets and many of the smaller larvae were undersampled because
of net extrusion. Based on the large decline from the 3.0- to the 4.0-mm size-class, highest mortality
probably occurred at that size. Larvae in this length reinge were a combination of Stage 1 during yolk
absorption and Stage 2 at first feeding. This apparent time of high mortality may represent the larval
winter flounder "critical period", a concept first hypothesized by Hjort (1926) and discussed by May (1974)
for marine fishes. They suggested that starvation may be a compensatory factor. This period "of high
mortality was not as evident in the catch curve of winter flounder larvae presented by Pearcy (1962) for
the Mystic River. But the dominant size-class in his catch curve was 3.5-mni and his use of a 363 — |j,m
net may have resulted in an undersampling of smaller larvae. The slight increase in percentage starting
with the 6.0-mm size-class in the river and bay probably represented decreased growth in length for Stage
3 and 4 larvae during metamorphosis with a concurrent increase in body depth. Laroche (1981) reported
that for winter flounder the percentage of body depth at the pectoral fin base to standard length increased
from 9% for yolk-sac larvae to 31% for transformed larvae. The increasing percentage of larvae from
smaller to larger size-classes in the bay again indicated that spawning primarily occurred in the river and
larvae were gradually flushed into the bay. In the bay over 50% of the larvae collected were in the 5.0-mm
and larger size-classes. Based on the length frequency-developmental stage relationship (Fig. 20), they
were mostly Stage 3 and 4 larvae. The decline in percentage at about 6.5 to 7.0 mm in the river and bay
represented the transition to demersal juveniles that were less susceptible to capture with a plankton net.

83

STAGE 1

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

LENGTH (MM)
STAGE 2

Figure 20. Length -frequency distribution of larval winter flounder by developmental stage for all stations combined
from 1983 through 1985.

84

STAGE 3

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

LENGTH (MM)

STAGE 4

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

LENGTH (MM)

Figure 20. cont.

85

NIANTIC RIVER.

NIANTIC BAY

n :

£ 5

^ 4

2^0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6,0 6.5 7.0 7.5 8.0 S.5 9,0

LENGTH (MM)

Figure 21. Length -frequency distribution of larval winter flounder for all stations combined in the Niantic River and
Bay from 1981 through 1985.

86

Tidal export and import

The potential export or import of winter flounder larvae from or to the Niantic River was investigated
in 1983 by sampling three ebb and flood tides at the time of maximum current velocity. Most of those
collected were Stage 3 (45%) and 4 (48%) larvae. Many more larvae were collected during a flood tide
(Fig. 22). This indicated that there was a net import of at least the later developmental stages into the
river from the bay.

To quantify the net exchange of larvae between the river and bay, additional sampling at the mouth
of the Niantic River was conducted in 1984 and 1985. Five tidal cycles were sampled at 1-h intervals.

2000

1600:

o 1200:

O

Ld

a: 800

400:

JZL

E F

E F

E F

MAY 9

MAY 9

MAY 16

DAY

NIGHT

DAY

Figure 22. Frequency and collection times of larval winter flounder taken at the mouth of the Niantic River during
maximum ebb (E) and flood (F) tidal currents.

87

The sampling dates were spaced over most of the larval winter flounder season to collect various devel-
opmental stages. In 1984, mostly Stage 1 and 2 larvae (92%) were collected on April 5 and on May 8
the larvae were primarily Stage 3 (85%). In 1985, all larvae collected on March 28 were Stage 1 and 2,
on April 29 most were Stage 2 and 3 (99%), and on May 28 Stage 3 was dominant (89%). A few Stage
4 larvae were collected on two of the sampling dates (May 8, 1984 and May 28, 1985). Examination of
the combined data from all five dates by percent occurrence of each developmental stage showed that
Stage 1 and 2 larvae were more abundant during ebb tides and Stage 3 and 4 during flood tides (Fig. 23).
Similarly, examination by size classes showed that larvae 4 mm and smaller were more abundcint during
an ebb tide and larvae 5 mm and larger were more abundant during a flood tide.

In order to determine if velocity measurements were comparable between ebb and flood tides, separate
quadratic polynomial equations were fitted to hourly velocity measurements combined from each of the
five ebb and flood tides sampled. Good fits were obtained with an R value of 0.96 for both equations.
The mean ebb duration was 6.8 h and flood duration was 5.8 h. The area under the curve for the flood
tide (299.6) was smaller than for the ebb tide (397.7), indicating that flood velocities were low due to
sampling location. To make ebb and flood velocities comparable, the flood velocities were estimated using
a technique presented in NUSCo (1986a). The calculations of net exchange of larvae which follow were
based on actual ebb current velocities and the adjusted flood current velocities.

Using data combined from the five sampling dates, net tidal exchange was estimated for each 1-mm
size-class. The estimates were obtained by summing the number per 500 m of larvae of each size-class
in each hourly sample for the five sampling dates. The sum was multiplied by the estimated water velocity
at the time of the hourly collection. This density-velocity adjustment accounted for changes in discharge
volume during the tidal cycle. Because larvae coUected during an ebb tide represented a loss from the
river, the density- velocity value was made negative. A harmonic regression equation using a 12.6-h tidal
cycle (the average duration of the five tides sampled) was fitted to density-velocity values. The area under
the curve for each tidal stage was estimated by numerical integration of the regression equation using
5-min increments. Net tidal exchange was expressed as the percent return of a size-class on a flood tide
compared to loss on a ebb tide (Table 27). The harmonic regression could not be fitted to the 2-mm
size-class, because so few were collected on a flood tide. The results showed a net export of 4 mm and
smaller size-classes and a net import of 5 mm and larger size-classes.

100"

90

80

70

i^ 60
o

^ 50

UJ

o

<^ 40

Q.

30

20

10

0

100

90

80

70

UA 60

(J3

^ 50

Ld
O

^ 40

30

20-

10-

0

E F
1

E F E F

2 3

DE^/ELOPMENTAL STAGE

E F
4

E F
2

E F
3

E F E F

4 5

LENGTH (MM)

E F
6

E F
7

Figure 23. Percent occurrence of each developmental stage and 1-mm size class collected at the mouth of the Niantic
River during ebb (E) and flood (F) tidal stages in 1984 and 1985.

89

The eight tidal cycles sampled since 1983 clearly indicated a net loss of smaller larvae that lacked fin
rays and had little or no locomotion. However, larger larvae with developed fin rays apparently utilized
vertical migration in relation to tidal currents for passive movement back into the Nicintic River. This
vertical migration of larvae after fm ray development was also apparent in the 24-h studies conducted at
station C in the river (Fig. 12). Other researchers also reported vertical migration in early life history
stages of fish. Diel movements of larval yellowtail flounder {Limanda femiginea) were found to increase
with larval size (Smith et al. 1978). Atlantic herring larvae synchronized vertical migration with flood tides
to minimize seaward transport (Fortier and Leggett 1983). Post-larval spot {Leiostomus xanthurus), Atlantic
croaker {Micropogonias undulalm), and Paralichthys spp. flounders used vertical migration in response to
tides as a retention mechanism (Weinstein et al. 1980). Larval North Sea plaice {Pleuronectes platessa)
demonstrated selective horizontal transport by swimming up from the bottom during flood tides and
remaining near the bottom during ebb tides (Rijnsdorp et al. 1985). Most winter flounder larvae found
in Niantic Bay probably were tidally flushed from the Niantic River during early developmental stages.
After fin ray development, at least some of the older larvae in the bay utilized vertical migration in relation
to tidal flow to reenter the river and those within the river demonstrated a similar behavior to remain there.

Table 27. Estimated percent return of larval winter flounder on a flood tide

that were Rushed from the river on an ebb tide presented by size-
class with R^ values of the harmonic regression models.

Size Percent R of

class return model

3 23.4 0.80

4 60.0 0.66

5 131.8 0.90

6 114.2 0.89

7 140.9 0.88

90

Post-larval stage

Abundance (age 0)

Post-larval young-of-the-year winter flounder were collected using a 1-m beam trawl from late May
through September of 1983-85 at stations LR and CO or WA in the Niantic River. By design, nets of
four increasing mesh sizes (0.8 to 6.4 mm) and increasing tow lengths (50 to 100 m) were used to maximize
efTiciency in catching young as they grew in size and declined in number. The lack of a tickler chain in
the beginning of the study in 1983 was subsequently found to have affected catches and resulted in
underestimates of abundance for the first 5 wk (NUSCo 1984). Data from that period were not included
in the following calculations of abundance or mortality.

Abundance of young winter flounder peaked in mid-June, most likely when larval recruitment began
to be ofi"set by mortality (Fig. 24). Catches tended to stabilize by July and appeared to fluctuate about
mean levels for the remainder of the season. Although densities for the first month were not known with
certainty, young at LR were probably initially more numerous in 1983 than in 1984 or 1985, based on
abundance later in the year. This follows the pattern of Stage 4 larval abundance given above (Fig. 14).
More variability was also evident for 1983 as only three replicate tows were taken per sampling trip rather
than the four made during 1984 and 1985. Densities at CO in 1983 were initially quite high, but quickly
fell to levels similar to LR by late June. SampUng at CO was hampered by the buildup of dense mats
of Enteromorpha clathrata, a filamentous alga. This station was dropped in favor of WA in mid- 1984.
Catch at WA was also more variable than LR, but densities appeared to be higher there than in the lower
river.

Growth and mortality (age 0)

Growth of young was illustrated by changes in weekly mean length (Fig. 25). Less variability was
seen in growth than abundance, especially at LR, with relatively small 95% confidence intervals found.
Most variation occurred at CO in 1983 with a large group of smaller individuals clustered about one mode
joined each week by a few larger specimens. Growth was significantly greater at LR than upriver at CO
or WA after mid-June. After a relatively rapid increase from about 12 to 50 mm from May through July,
further growth occurred at a slower rate throughout the remainder of summer with little or no increase in
weekly means during September.

91

(0

90-

ir

IlI

^1

80-

2

III

<

/o-

)

n

t/)

60-

o

o

(T

bU-

III

a.

-r

40-

C )

1—

<

u

j50-

7^

r^

2

20-

V

_l

hi

10-

liJ

5

0-1

Station CO

83

MAY JUNE

JULY

AUGUST SEPTEMBER

50

40

o 30

20

10

0-L

Station WA

84

/ V I / \ A

85 ^-' \ / \

MAY JUNE

JULY

AUGUST SEPTEMBER

Figure 24. Weekly CPUE of young winter flounder talcen in the Niantic River from 1983 through 1985.

92

ti

50

40

30-

20

10-

btation LR

/ \ ^ \

/ \ \ v

/ V ^ A

J \ ^ / \

/ ^ \ V/ \ x^ \

/ ■

85 ^ ' ^^>^

//

MAY

JUNE

JULY

AUGUST

SEPTEMBER

Figure 24. cont.

Weekly means at LR during 1983-85 were similar by year until about late June; means were 6 to 8
mm greater thereafter during 1983 (Fig. 26). Those during 1984 and 1985 were more alike with growth
slightly less during the latter year. The reasons for these differences among years are not known. Although
water temperatures appeared to be comparable, life history data such as food preference, rates of feeding,
and predation upon young are not available. Apparent annual changes in growth may also be caused by
differential movement of larger young away from the station, which would also increase the apparent
mortality rate. However, only a few average-sized young were taken during the summer at trawl station
NR and none at the Niantic Bay stations. Thus, neither large-scale movements nor differential movements
by size seemed to have occurred, at least into areas sampled by trawl.

93

90
80
70
60
50
40
30
20
10

1983

MAY JUNE

JULY

AUGUST

SEPTEMBER

70-

1984

T

■^\ i

k

60-

LR

>4^

K^,/l

"^

2

X

}—
o

z

LU

_1

50-
40-
30-

^A CO

WA

y^

Ld

5

20-

10-

n-

y;^-

^f''

MAY JUNE

JULY

AUGUST SEPTEMBER

Figure 25. Weekly mean length (± 2 standard errors) of young winter flounder taken in the Niantic River from 1983
through 1985.

94

701
60
I 50

X

I 40

LiJ

i^ 30
if, 20

10

1985

HA-h-l

MAY JUNE

JULY

AUGUST SEPTEMBER

Figure 25. cont.

The instantaneous mortality rate (Z) of post-larval winter flounder was previously reported (NUSCo
1984, 1985, 1986a) using a method described by Jones (1981). Parameters required for this procedure
included the cumulative catch of young by length increment and the parameter K of the previously
described von BertalanfFy growth model. For young, /.oo of the model was fixed at 95 mm for LR and
75 mm for WA fish, or slightly larger than the length of the largest specimen found at each of the stations
(NlJSCo 1986a). Although not included in this report, analysis of data collected in 1986 indicated that
selection of a fixed Loo and the maimer in which the cumulative length increments were chosen most likely
biased estimates of Z. Therefore, catch curves were constructed using annual abundance data from LR
for 1983-85 and WA for 1985. No analysis was attempted for CO due to sampling problems affecting
abundance estimates. The catch curve method may also be criticized as young were assumed to have
comprised a single-age cohort which was followed from week to week during the sampling season.

95

80-

btation LR

70-

^~\_— 83

60-
50-
40-

30-

y^

//

20-

yy

MAY JUNE

JULY

AUGUST SEPTEMBER

Figure 26. Comparison of weekly mean length of young winter flounder taken at station LR in the Niantic River from
1983 through 1985.

The catch curves for LR had relatively good fits with r^ ranging from 0.60 to 0.83 (Fig. 27).
Remarkably similar values of Z were obtained, resulting in monthly survival estimates of 0.552 to 0.569.
A larger estimate of survival was found for WA (0.661). This is in contrast to the more variable survival
estimates determined by the method of Jones (1981) and reported in NUSCo (1986a). The monthly
survival estimates at station LR in the Niantic River were less than the value of 0.69 reported by Pearcy
(1962) for the Mystic River estuary, which is the only published estimate for young winter flounder.
Factors affecting the survival of young are unknown, but predation and disease probably cause most
deaths. The piscivorous summer flounder {Paralkhthys dentatm) reached peak abundance during the past
decade in the Niantic River during 1984, when it was 2.75 times more numerous than in 1983. However,
in 1985 its numbers fell to levels slightly below those in 1983. The abundance of other predators of
juvenile winter flounder commonly found during the summer in the Niantic River, such as the double-crested
cormorant {Phalocrocorax auritus), grubby (Myoxocephalus aenaeus), and bluefish (Pomalomus saltatrix),
have not been studied.

96

3-

2-

1983 - LR

Z = 0.137
S (weekly) =0.872
S (monthly) = 0.552
r^ = 0.60

MAY

JUNE

JULY

AUGUST

SEPTEMBER

4-

2-

1984 - LR

Z = 0.132
S (weekly) = 0.876
S (monthly) = 0.564
r2 = 0.79

MAY

JUNE

JULY

AUGUST SEPTEMBER

Figure 27. Mortality determined by catch curve for Niantic River young winter flounder from 1983 through 1985.

97

1985 - LR

*

* ^^\.

*

* *

--

*

*

*

Z = 0.130

*

*

*

S (weekly) = 0.878
S (monthly) = 0.569
r^ = 0,83

*

*

*

*

MAY

JUNE

JULY

AUGUST

SEPTEMBER

2-

1985 - WA

Z= 0.095
S (weekly) = 0.909
S (monthly) = 0.661
r2 = 0.56

MAY JUNE

JULY

AUGUST SEPTEMBER

Figure 27. cont.

98

The microsporidian parasite, Glugea slephani, was observed in some individuals collected. Mortality
caused by this parasite can be relatively high in winter flounder (Takvorian and Cali 1984; Cali et al.
1986). Incidences of the pathenogenic bacterium Vibrio anguillarum, which also can result in fatal infections
in winter flounder characterized by fm erosion, dermjd ulceration, and hemorrhaging (Levin et al. 1972;
Watkins et £il. 1981; Sindermann 1985), were not noted.

Abundance (age 1)

An attempt was made in 1981 and 1982 to estimate with the Jolly model the abundance of 6- to
1 5-cm juvenile winter flounder present in the Niantic River during the spawning season. Fish were marked
with freeze-brands during the adult surveys in late winter and released. However, apparent high rates of
marking mortality made the Jolly estimates biased and unreliable (NUSCo 1983a) and no further attempts
were made to mark small fish.

The median CPUE of juvenile winter flounder smaller than 15 cm in length was calculated for fish
taken during the adult winter flounder surveys in the Niantic River from 1976 through 1986 (Table 28,
Fig. 28). Nearly all of the fish in this size grouping were age 1 yearlings and represented the year-class
spawned during the previous abundance survey. Data were restricted to the mid-March to mid-April
period for comparability among years and to stations 1 and 2 because small winter flounder appeared to
have been less abundant in the upper river than adults. Inclusion of data from upper river stations could
have biased inter- year comparisons because few or no tows were made there prior to 1981.

Juvenile catches were more variable than those of adults and had larger coefficients of variation and
skewness. Less uniformity was seen between the median and mean, even after tows were standardized in
1983. Peak abundance was observed in 1981 (1980 year-class), with a median of 87.2. Second and third
highest medians were found in following years (61 in 1982, 50.1 in 1983). Abundance declined greatly in
1984 to a median of 16, increased to 27.7 in 1985, and fell to an ll-yr low of 3.6 in 1986. Juvenile
abundance, which began to increase in 1979 and peaked in 1981, was generally followed by increasing
adult abundance, which peaked in 1982. Abundance of both groups declined through 1984. Juvenile
catches were recently reported to have been correlated with adult abundance a year later (NUSCo 1986a),
but the addition of 1986 data made this relationship non-significant. Although juvenile CPUE in 1985
was 73% larger than that in 1984, adult abundance did not increase in 1986.

99

Table 28. Mean and median CPUE of Niantic River winter flounder smaller than

15 cm from 1976 through 1986 during the period of mid-March through
mid-April (stations 1 and 2 only).

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

Total tows made

80

143

100

79

101

47

39

44

41

48

37

Tows used for CPUE

64

116

84

71

90

45

39

44

41

48

35

% of tows used

80%

81%

84%

90%

90%

96%

100%

100%

100%

100%

95%

Mean CPUE

22.2

31.2

26.4

50.2

55.9

97.7

72.2

50.8

22.9

36.4

6.7

Standard deviation

17.5

26.6

28.5

54.1

43.7

65.2

58.9

35.0

27.2

25.6

7,3

CoefF. of variation

79%

85%

108%

108%

78%

67%

82%

69%

119%

70%

109%

Median CPUE

18

25.5

16.1

27

48.7

87.2

61

50.1

16

27.7

3.6

95% CI

13.5

18.0

10.2

17.4

33.8

61.0

46.5

32.8

9.9

20,9

2.5

-25

-30.9

-25

-42.3

-60

-120.9

-86.3

-61.2

-20.4

-41.1

-8.7

CoefF. of skewness*

0.81

1.10

1.81

1.88

1.14

0.67

1.00

0.58

2.71

1.00

1,51

Zero when data are distributed symmetrically

1251

5
c/i a:

y ^100

> o

o z 75

UJ Ld
=) X
0- 1-

CM 50

25

76

77

78

79

80

82

83

84

85

86

YE>\R

Figure 28. Annual median trawl CPUE (±2 standard errors) of age 1 winter flounder at stations 1 and 2 in the Niantic
River from 1976 through 1986. CPUE based on a tow standardized to a 15-min duration.

100

The observed abundance of juvenile winter flounder during the 4-wk period may not accurately reflect
their absolute abundance. Unlike adults, juveniles do not necessarily enter the river during the spawning
season and other factors may influence their movements. However, similar to adults, annual differences
in late winter-early spring water temperature did not seemingly correspond with abundance inside or
outside of the river. Additional data were examined to determine how accurate the juvenile CPUE was
as a predictor of year-class strength. Since many tows were made in the upper river after 1980, median
CPUE were calculated which included all tows in the river during the comparable 4-wk time period. These
data showed less difference in abundance between 1981-83 and 1984-86 than median CPUE for the lower
river channel stations 1 and 2 alone (Fig. 29). This indicated a greater use of the entire river in recent

90 i

80

70-

=5 60

Ll.

o

y 50

40-

P: 301

-z.

<

R 20

10

0-i

76 77 78 79 80 81 82 83 84 85 86

YEAR

Figure 29. Comparison of median trawl CPUE of age 1 winter flounder at various stations in and outside of the
NiantJc River from 1976 through 1986. CPUE are consistent within station groupings but are not
equivalent (see Materials and Methods).

101

years by juveniles. As areal distribution increased, concentrations in the lower river most Ukely decreased.
This confounds the use of an abundance index based on tows from only the lower river channel stations.

Juvenile abundance data were also available from the trawl monitoring program for January through
April at the five stations outside the river. These CPUE values show generally uniform densities of
juveniles from 1976 through 1982 (Fig. 29). A sharp increase occurred in 1983 followed by a decline to
average levels in 1984 and 1985 and an increase to another peak in 1986. CPUE values were close in
magnitude to those determined for slightly shorter tows in all areas of the river during 1981-86. However,
the 1986 median was significantly greater than the values obtained for the lower river channel and for the
entire river. The low abundance in the river during 1986 may not be indicative of the true abundance of
the 1985 year-class, which may have been less concentrated in the river than others observed. Because of
the disparities among the various estimates, the relative abundance of juvenile winter flounder is known
with less certainty than that of adults, which are found mainly in the river during winter and early spring.

Impingement

Abundance

Estimates of the number of winter flounder impinged on the traveling screens of MNPS are available
from 1972-73 through the present. With the installation of a fish return sluiceway at Unit 1 in December
1983, the the estimated total of 2,926 in 1984-85 was the second lowest of the 13-yr series (Table 29).
Most armual estimates for two-unit impingement ranged from 4 to 10 thousand, with an exceptionally
high estimate of 24,494 in 1978-79. Since 1976, it has been the second most abundant fish impinged at
MNPS, making up 8.4% of the total. If one large impingement event (over 400,000 on one day in July
1984) of sand lance {Ammodytes americanus) is ignored, the winter flounder would rank fu-st among all
fishes. About two thirds were impinged during winter and relatively few were taken in summer.

Precision of winter flounder impingement estimates should have increased following 1982-83. Using
a resource allocation analysis suggested by El-Shamy ( 1979), the number of samples was changed from a
uniform number per month to a variable schedule, specifically reflecting the variability of winter flounder
impingement (NUSCo 1983b). More samples were taken in February and March and fewer in other

102

months, resulting in an approximate 50% reduction in sampling effort (NUSCo 1984).

Table 29. Estimated total number of winter flounder impinged on the intake screens of

MNPS by season and year from October 1982 through September 1985 ^

Year"

FaU

Winter

Spring

Summer

Total

% by year

% of all fish

1972-73

405

4,404

1,184

170

6,163

6.2

37.9

1973-74

462

2,663

564

124

3,813

3.8

28.9

1974-75

384

1,666

354

185

2,589

2.6

27.0

1975-76

757

2,409

764

107

4,037

4.0

15.6

1976-77

2,377

4,858

2,250

143

9,628

9.6

32.8

1977-78

371

4,127

1,685

154

6,337

6.3

17.4

1978-79

1,710

17,753

3,884

1,147

24,494

24.5

32.7

1979-80

760 .

3,377

2,471

309

6,917

6.9

20.0

1980-81

1,050

4,406

1,329

377

7,162

7.2

12.3

1981-82

1,528

6,240

1,529

528

9,825

9.8

15.8

1982-83

578

7,678

2,005

699

10,960

10.9

7.5

1983-84

3,085

1,811

305

106

5,307

5.3

1.0

1984-85

320

2,170

304

132

2,926

2.9

13.2

Total

13,787

63,562

18,628

4,181

100,158

—

...

% by

13.8

63.5

18.6

4.2

...

...

...

Season

* Estimates for Units 1 and 2 from October 1972 through December 1983 and for Unit 2 thereafter.
October through September

Impingement estimates in themselves do not reflect absolute abundance of a species, but are related
to plant design and operational characteristics; time of day; and environmental variables such as water
temperature, wave height, wind direction and velocity, and precipitation (Grimes 1975; Landry and Strawn
1975; Lifton and Storr 1978). Severe windstorms combined with falling water temperatures particularly
have been correlated with increased impingement of fish at MNPS and elsewhere (Thomas and Miller
1977; Lifton and Storr 1978; NUSCo 1981a, 1983a, 1986a). Eleven instances were found when weekly
winter flounder impingement estimates exceeded 1,000 individuals; these samples were examined along
with available relevant meteorological data (Table 30). The impingement on these days made up a
considerable portion of seasonal and annual estimates. Six of the events occurred in 1979 and accounted

103

Table 30.

Instances of weekly winter flounder impingement estimates of greater than
1,000 individuals and associated meteorological data from October 1972
through September 1985.

Date

Weekly
imp. est.

Mean daily
wind speed

Avg. wind
direction

Mean
daily water
temp. (C)

Remarks

1

12-21-76
12-22-76

1,376

21
18

WNW
W

4.7
3.5

Water temperature declined
2°C during storm

2

3-24-77
3-25-77

1,292

18
18

NW
NW

2.9
2.6

3

4

1-09-78
1-10-78

1-24-79
1-25-79

1,292

2,472

28
31

17
14

sw
w

ENE
S

4.9

2.7

4.3
4.1

Among the highest average daily wind
speeds since 1975; rapid drop in
temperature.

5

1-30-79
1-31-79

1,229

16
12

NW
NW

4.1
4.1

6

2-5-79
2-6-79

7,889

23
21

WNW

NW

2.3
1.2

Water temperature declined 3"C in 3
days.

7

2-26-79
2-27-79

1,050

12

7

NE
SSW

1.5
1.6

8

3-13-79
3-14-79
3-15-79

2,054

11
19

17

s
sw

WNW

2.5
3.0
2.5

4-2-79 1,152 20 E 5.0

10 1-4-82 2,643

1-5-82

12-28-83 1,559

12-29-83

24

SE

4.8

22

W

4.7

23

S

5.4

14

WNW

5.6

Miles per hour,
for almost two-thirds of the abnormally high total for that year; one-third of the total alone was from one
storm in early February. In most cases the large impingement estimates were associated with sustained
daily wind velocities of about 16 mi/h (26 km/h) or more and water temperatures of 5.5 °C or less. Events

104

associated with winds from the northwest probably resuUed from the passage of cold fronts with accom-
panying falling temperatures and winds from the southwest were perpendicular to the MNPS intakes: The
combination of low water temperatures and frequent high winds in winter (NUSCo 1983c), along with
less sustained swimming speed and endurance for the winter flounder at colder temperatures (Beamish
1966; Terpin et al. 1977) most likely makes it more susceptible to impingement then. Strong winds alone
do not necesscirily increase impingement as 3 weeks prior to the December 1983 incident sustained winds
of 21 to 35 mi/h from the south to west over a 2-d period only produced a weekly estimate of 145 winter
flounder. The water temperature then was 9.5 to 9.8 °C.

Length and sex distribution

The length-frequency distribution of impinged winter flounder by 5-cm length groups showed that the
proportion of adults (fish larger than 25 cm) has remained relatively constant and made up about a third
of each annual total (Table 31). Catch of mid-sized (15- and 20-cm length groups) and small fish (5 and
10 cm) varied from year to year. Mid-sized fish made up more than half the total in 1977-78, but only
one-fifth in 1984-85. About 40% of the catch in 1978-79, 1982-83, and 1984-85 was comprised by small
specimens. As noted above, factors such as plant operating conditions and weather influence impingement
to a great extent and relative differences in abundance and size-classes impinged each year probably do
not reflect actual changes in the winter flounder population.

The sex and reproductive condition were examined for 755 winter flounder impinged from February
through April of 1982 and 1,675 from December 1982 through April 1983. The sex ratio in 1982 was
1:1, but males predominated earlier in the season and females later. In 1982-83, 65% were males and
35% females, a ratio opposite to that seen for the Niantic River spawning population. Of the females 25
cm or larger examined from mid-February through April of 1982 and 1983, 56 and 59%, respectively,
were gravid. This was contrary to fmdings from the trawl monitoring program for the same period, which
showed relatively few ripe winter flounder outside of the Niantic River. In addition, a comparison of the
weekly percentages of gravid females inside the Niantic River with those impinged showed that a much
larger portion of the latter had not spawned (Fig. 30). Although sample size was considerably smaller,
relatively higher percentages of gravid females continued to be taken at MNPS until the end of April,
whereas most fish in the river spawned earlier in the season.

105

Table 31. Annual mean length 2ind percent length-frequency distribution by 5-cm size

intervals of winter flounder impinged at MNPS from October 1976 through
September 1985.

Number

Mean

% length-frequency

Year

measured

length (cm)

cv

5

10

15

20

25

30 -^

1976-77

4,594

19.5

45%

7

22

16

16

16

23

1977-78

2,653

16.9

43%

12

16

29

23

12

8

1978-79

4,639

16.1

51%

17

23

24

12

13

11

1979-80

2,654

22.3

36%

1

9

25

16

18

31

1980-81

2,197

20.1

45%

7

19

18

13

18

25

1981-82

2,973

20.1

42%

6

10

28

20

13

21

1982-83

3,636

18.0

51%

7

32

19

9

14

20

1983-84

1,213

20.2

41%

5

15

21

21

19

20

1984-85

577

17.8

55%

16

27

10

11

14

23

The occurence of many fish in spawning condition at MNPS may have been partly related to behavior.
The enviromnental cues used by winter flounder to successfully return to the Niantic River from distant
areas for spawning are not known. Beverton and Holt (1957) and McKeown (1984) noted that currents
are among the important factors in guiding oriented migration of demersal marine fishes. If adult winter
flounder move along the shoreline in search of a particular estuary, then the intake currents at MNPS
may attract individuals seeking to enter the river for spawning. Also, the larger numbers of males impinged
than females may be related to their generally smaller size and therefore lower sustained swimming speeds
(Beamish 1966; Tcrpin et al. 1977), which would have allowed fewer of them to escape from the intake area.

Fish return sluiceways

A fish return sluiceway was installed at MNPS Unit 1 and put into operation in mid-December of
1983. A sluiceway was constructed at Unit 3 and has been in operation since the start of commercial
operations in late April of 1986. Survival studies completed before (NUSCo 1981b) and after (NUSCo
1986b) installation of the Unit 1 sluiceway indicated that future impingement mortality of winter flounder
at MNPS would most likely be less than 20% (Table 32). Data restricted to only colder months, when

106

100
90
80

CO

^ 70

:5

Ld

U- 601

Q

^ 50

or

CD

^ 40

UJ

DC 30

Ld

n.

20

10

0-^

83 IMP 82 IMP

FEBRUARY

MARCH

APRIL

Figure 30. Percentage of adult female winter flounder in spawning condition by. week taken in the Niantic River (NR)
and on the traveling screens at MNPS (IMP) during 1982 and 1983.

Table 32. Percent initial and extended survival of winter flounder impinged on the

MNPS Units 1 and 2 traveling screens.

Time between

Number

% initial

% extended

% overall

Date

screenwashes

examined

survival

survival^

survival

1980-81

Continuous

133

97

100

97

2h

146

98

94

92

4h

175

97

91

88

8h

164

96

95

92

1984-85

6h

44

93

88

82

60-h holding period in 1980-81 and 72-h in 1984-85.

107

most winter flounder were impinged, showed even greater (90%) survival. These estimates were similar
to those reported for winter flounder at several other power plants (Tatham et al. 1977; MR! 1982).

One potential problem in returning fish is recirculation and re-impingement, which would increase
the probability of mortality. On seven occasions during 1981-83, a total of 299 disc-tagged winter flounder
was released near a rock outcrop between Units 1 and 2 (Table 33). Only 15 (5%) fish were impinged,
80% of them within 3 d of release. In comparison, 17 fish were later recaptured by the sport and
commercial fisheries (4 to 735 d after release). Only once was more than two fish impinged. This occurred
after the June 3, 1981 release, when seven of the nine recaptures for this group were made within 2 d;
these were the only fish released at night. A small percentage of winter flounder may be susceptible to
re-impingement, especially at night or perhaps during storms. However, the Unit 1 sluiceway terminus is
farther from the intakes than the centrally located release point. On ebb tides the flow could carry fish
away from the MNPS intakes, depending upon their orientation to currents.

Table 33. Summary of winter flounder tagged and released near the intakes of

MNPS Units 1 and 2.

Number recaptured

Date of Source Number Sport Commercial NUSCo Percent Percent

release of fish released Impinged fishery fishery trawling* impinged recaptured

2 June 1981 Trawling 109 1 7 1 7 0.9 14.7

3 June 1981 Trawling 89 9 1 10 10.1 12.4
29 Mar. 1982 Impingement 15 0 3 1 1 0 33.3
5 Apr. 1982 Impingement 18 1 0 0 0 5.6 5.6
12 Apr. 1982 Impingement 8 1 0 0 0 12.5 12.5
26 Apr. 1982 Impingement 20 1 2 1 0 5.0 20.0
7 Mar. 1983 Impingement 40 2 0 0 2 5.0 10.0

Total 299 15 13 4 10 5.0 14.0

All released alive; 3 subsequently recaptured a second time and included in above totals.

108

The sluiceways at Units 1 and 3 should substantially reduce the impact of impingement on juvenile
and adult winter flounder. This is particularly important as apparently a relatively large proportion of
impinged adults did not spawn before encountering the intakes. Studies at NUEL are currently underway
to examine the effectiveness of the Unit 3 sluiceway in returning winter flounder and other species to
Niantic Bay.

Entraiiunent

Abundance

Sampling at the discharges of MNPS Units 1 and 2 to estimate the number of winter flounder larvae
entrained through the condenser cooling water system has been conducted since 1 976. This is the longest
time-series of data at NUEL with consistent yearly sampling on the abundance of larval winter flounder.
Generally, larvae were entrained from late February through the end of June with greatest densities from
mid- April through May. Over 60% of the larvae entrained during the 10-yr period were 5.0 mm and
larger (Fig. 31). Since 1983, the proportion of Stage 1 larvae entrained was 2%, Stage 2 was 31%, Stage
3 was 56%, and Stage 4 was 11%. As stated previously, smaller larvae are not abundant in the Niantic
Bay and therefore are less susceptible to entraiimient.

Since 1982, the median has been used as a measure of the armual entrainment density and in calculating
the total number of winter flounder larvae entrained. A median was used instead of a mean because the
data were highly skewed and the median was a better estimate of central tendency (NUSCo 1983a).
Selection of the time period used to calculate the median was changed for this report. Previously, the
median calculations were based on an annual time period selected by examination of the aimual density
distribution over time with an arbitrary determination of the beginning and end of the season. For this
report, the season was determined as the period in which 95% of the total cumulative abundance occurred,
excluding samples containing the first and last 2.5% of the cumulative abundance over time. This method
reduced the number of zero density values used in the calculations. Prior to 1982, entrainment estimates
were based on weekly means multiplied by the total weekly volume of water passing through MNPS.
These weekly values were then summed for an annual estimate, but confidence intervals could not be
calculated. Comparison of the results of these three methods (NUSCo 1983c, 1986a, and this report)
indicated large discrepancies among the the estimates. Further evaluations of techniques for estimating

109

12:
11 -
10

9

8

7i

6

5i

4

3

2-

1 :

2.0 2.5 3.0 3.5

4.0 4.5 5.0 5.5 6.0 6.5
LENGTH (MM)

7.0 7.5 8.0 8.5 9.0

Figure 31. Length-frequency distribution of larval winter flounder entrained at MNPS from 1976 through 1985.

annual entrainment numbers should be undertaken to establish the most credible estimates of entrainment
for impact assessment.

The median entrainment density has declined since 1983, which agreed with the decline in the cumu-
lative frequency in Stage 2 through 4 larvae at this station (Table 34; Fig. 14). The median densities
may be grouped into high and low years based on the lack of overlap of the 95% confidence intervals
with three low years (1977, 1978, and 1979) and four high years (1976, 1980, 1982, and 1983). The
confidence intervals of the remaining three years (1981, 1984, and 1985) overlapped either or both of the
low or high groups. A similar but slightly different grouping of actual entrainment estimates was found
with three low years (1977, 1979, and 1981) and four high years (1976, 1980, 1982, and 1983), with
remaining years overlapping. The total entrainment estimates took into account the volume of water
withdrawn for condenser cooling and may vary according to plant operations.

110

Table 34. Yearly median densities (n per 500 m^) of winter flounder larvae in en-

trainment samples during their season of occurrence and annual entrain-
ment estimates with 95% confidence intervals for MNPS Units 1 and 2
from 1976 through 1985.

Year

Median

95% CI

Estimate (xlO^)

95% CI (xlO^-)

1976

158.0

114.2 - 185.1

95.5

69.0 - 111.9

1977

68.3

54.5 - 96.3

30.9

24.7 - 43.6

1978

86.6

65.0 - 106.4

58.4

43.8 - 71.7

1979

90.3

69.7 - 108.4

36.6

28.2 - 43.9

1980

201.5

163.6 - 234.6

140.1

113.7 - 163.1

1981

139.2

99.3 - 182.6

47.6

33.9 - 62.4

1982

183.5

147.5 - 215.1

137.1

110.3 - 160.7

1983

244.4

158.1 - 314.8

172.9

111.9 - 222.6

1984

185.5

107.5 - 226.2

90.0

52.2 - 109.8

1985

107.1

78.8 - 149.5

65.9

48.5 - 92.1

The 10 yr of entrainment data provided an opportunity to examine factors that would affect annual
abundance and the timing of peak entrainment. The Gompertz function (Equation 6) was fit to the data
to compare the a parameter as an index of abundance to the median entrainment density and to compare
annual estimated dates of peak abundance (Table 35). A high correlation was found between the median
and the a parameter (Spearman's rank correlation coefficient = 0.855; p = 0.0016), showing that the a
parameter was a good index of abundance. The annual abundance of entrained larvae appeared to be
related to annual egg production in the river (Fig. 32). A linear regression was fitted to the total egg
production index (Table 11) versus the a parameter. The 1980 total egg production index was excluded
from the analyses because of the previously discussed problems with data from that year. The relationship
between egg production and entrainment abundance suggested that natural mortality from hatching to the
time of entrainment was similar for the 8 yr examined.

Ill

Table 35. The a parameter as an index of abundance and the date of

inflection as an estimate of the date of peak abundance from the
Gompertz function for larval winter flounder entrained from 1976
through 1985.

Date of

Year

a

inflection

1976

2321

13 Apr

1977

1263

18 May

1978

2476

8 May

1979

1665

1 May

1980

3216

24 Apr

1981

1693

5 May

1982

3012

28 Apr

1983

3565

18 Apr

1984

2568

27 Apr

1985

1951

17 Apr

The estimated date of peak density at EN varied from April 13 in 1976 to May 18 in 1977. For the
period of 1981-85, a similar pattern in the timing of peak abundance was also evident in the abundance
curves for Niantic Bay with stations NB and EN combined (Fig. 13). The estimated date of peak
abundance was determined from the inflection point of Gompertz function. This inflection was caused
by the decline in larval abundance and for EN data the decline was partly caused by the decrease of larvae
through recruitment to the juvenile stage. Because water temperature could affect the rate of development
to juveniles, temperatures during the entrainment season were compared to the timing of peak abundance
(Fig. 33). Temperature was expressed as the yearly deviation during March through May from the average
temperature for the 10-yr period. Time of peak abundance was the number of days after February 15
that the peak occurred each year. It appeared that as water temperature increased, the date of peak
abundance was earlier. This could be related to faster developmental rate to the juvenile stage or changes
in annual time of spawning (Fig. 5) due to water temperature. Although other factors could affect these
parameters, it was apparent that numbers entrained were probably related to total egg production in the
Niantic River and the length of time a larva was susceptible to entrainment, which was in turn related to

112

4 5 6 7 8

TOTAL EGG PRODUCTION INDEX xlO

10

Figure 32. The relationship between the a parameter (y) as an index of the annual abundance of winter flounder
larvae entrained and the annual total egg production index (x) in the Niantic River from 1977 through
1985 with the fitted linear regression of: y = 1164.7 + 191.8 (x); r^ = 0.56.

water temperature affecting growth and development.
Survival

Thermal tolerance studies on larval winter flounder were conducted to estimate the effect of increased
temperatures on larvae during entrainment (NUSCo 1975). Larvae were grouped as pre-metamorphosed
(less than 5.0 mm) and metamorphosing (5.0 mm and larger). Larvae were exposed to a AT of 13 °C
using an acclimation temperature of 8 °C. Mortality increased with exposure time for pre-metamorphosed
larvae from 29% at 1 h, 48% at 2 h, 53% at 3 h, to 89% at 6 h. No mortality occurred for metamorphosing
larvae with exposures up to 9 h. Because most larvae entrained were 5.0 mm and larger (Fig. 31) and

113

06APRHt

-2.0

-1.0 -0.5 0.0

TEMPERATURE DEVIATION (C)

Figure 33. The relationship between the estimated annual date of peak abundance (y) of entrained winter flounder
larvae and the annual temperature deviation (x) during March-May with the fitted linear regression of:
y = 72.0 - 10.7 (x); r^ = 0.53.

the retention time in the quarry with 2-unit operations was approximately 3 h, most larvae would survive
the thermal increase due to entrainment, but not necessarily any mechanical damage.

The critical thermal maximum was determined by increasing the water temperature from 8 °C at a
rate of 1 °C per min until total mortality occurred. The critical thermal maximum was 25 to 26 °C for
pre-metamorphosed and 24 to 26 °C for metamorphosing larvae. Water temperatures in the quarry
generally reached or exceeded 24 °C by mid-May. Whether the critical thermal maximum temperature
actually represents the maximum temperature that larval winter flounder can survive is doubtful because
an almost 15 °C rise in less than 20 min would not provide a period for acclimation at each temperature.
Furthermore, the CTM may vary according to any particular acclimation temperature (NUSCo 1975).

114

Entrainment mortality studies were conducted in 1983 on larvae that had passed through the plant
(NUSCo 1984). A total of 135 winter flounder larvae was collected during 11 sampling sessions (Table
36). During the study the effluent ^T ranged from 8.0 to ILSX. Of the 24 Stage 2 larvae collected, 8
were alive following capture but none survived the 2- to 4-h effluent holding period. Stage 3 larvae had
greater survival than Stage 2 following capture and the effluent holding period, but all survivors died during
the first 24 h of the latent holding period. All 24 Stage 4 larvae were alive following capture, with 19
(79%) surviving effluent and 96-h latent holding periods. From 1983 though 1985, 11% of the larvae
entrained were Stage 4 and many of these most likely would have survived passage. These older larvae
would also have had a greater probability of recruitment to the adult stock than the younger stages.
Survival of larger winter flounder larvae entrained would reduce the estimated effects in previous assessments
(Hess et al. 1975; Saila 1976; NUSCo 1983c), which assumed 100% mortality for entrained larvae.

Table 36. Results of larval winter flounder entrainment mortality studies.

Number

Alive at

Surviving

Surviving 96-h

Stage

captured

capture

effluent holding

latent holding

2

24

8

0

0

3

87

69

15

0

4

24

24

19

19

Total

135

101

34

19

Impact assessment

The potential impact of the 3-unit MNPS over its operational lifetime on the Niantic River population
of winter flounder has been addressed by a deterministic impact assessment model. This model was
developed under the direction of Dr. Saul Saila of the University of Rhode Island and has been described
in numerous reports to NUSCo as well as in the scientific literature (Sissenwine et al. 1973, 1974, 1975;
Hess et al. 1975; Vaughan et al. 1976; Saila 1976). The model is subdivided into hydrodynamic, concen-
tration, and population submodels and examines the entrainment of winter flounder larvae, which are

115

assumed to come from the Niantic River, as the major impact of MNPS operations. The latest application
of the model was for the MNPS Unit 3 Environmental Report - Operating License Stage (NUSCo 1983c).
Based on data from the literature as well as from NUEL studies at the time of the model run, a potential
5 to 6% decrease in winter flounder abundance was projected to occur after 35 yr of plant operations.
The population would recover to within 1% of the equilibrium level after an additional 65-yr period.

It was emphasized in NUSCo ( 1983c) that the above model results were probably conservative. The
effects of entrainment were overestimated since vertical stratification of larvae and vertical variations in
current velocity were ignored, as was the potential for a fraction of the entrained larvae to survive, and
because of input of larvae from outside the Niantic River. The immigration of winter flounder from other
stocks into the area; density-dependent growth, fecundity, adult mortality; and, in some cases, density-
dependent larval mortality were not considered. Criticisms could be made of many of the model assump-
tions, particularly the ones made for estimating the Ricker (1954) stock-recruitment function parameters.
Nevertheless, the model has been independently evaluated and found to be an acceptable, conservative
method of assessing MNPS impact (Gore et al. 1977; Thomas et al. 1978).

Some mathematical representation of the recruitment process is common to many fisheries population
models. Since egg and larval survival is more dependent upon environmental factors than adult survival,
a prominant feature of recruitment data for many species is the large amount of variability present (Jones
1982). In spite of this, deterministic population models use recruitment equations which have constant
parameters and assume either no adult age-structure or stable age-structure implying equilibrium. However,
models that take into account the effects of natural variability in the recruitment process have become
available recently. A stochastic population dynamics model, based on work by Lorda (1982) and Reed
et al. (1984), is currently being modified at NUEL to incorporate detailed early life history and temperature
effects on larval survival. This model explicitly uses the natural variability of some key population
parameters and data collected specifically for the Niantic River winter flounder stock. In recent years,
increased emphasis has been placed on understanding the dynamics of the early life history stages. The
factors governing the production and mortality of larvae should be known before assessing the impact of
MNPS operations. In particular, the quantification of larval mortality and its partition into density-dependent
and -independent components can be expected to be critical for the realistic estimation of entrainment
effects. Model results will include a probabilistic risk assessment analysis, which should provide better

116

and more realistic estimate of potential losses to the winter flounder population caused by the operation
of MNPS.

CONCLUSIONS

The Niantic River population of the winter flounder has been studied since 1976 because of its
importance to the sport and commercial fisheries of Connecticut and the potential for impact by MNPS
operations, especially from entrainment of larvae. Studies of adult winter flounder spawning in the river
have provided a time-series of data for impact assessment, including adult stock size, reproduction, move-
ments, exploitation, and rates of growth and mortality. Similarly, estimates of impingement and entraiimient
during the same time period were available to measure impact. Since 1983, increased emphasis was placed
on understanding critical early life history stages of winter flounder in the Niantic River. To date, there
is no evidence that MNPS has significantly affected the winter flounder population. Periodic cycles in
abundance are typical for this species throughout its range. Although numbers of adults have declined in
recent years, the decrease apparently has been due to natural causes or perhaps from an increase in
commercial fishing in Southern New England.

Events during the larval stage within the Niantic River are most important in determining the success
of a year-class and their understanding is still incomplete. The factors which govern the production and
mortality of larvae must be known before assessing the impact of power plant operations. Quantifying
larval mortality and partitioning it into density-dependent and -independent components will allow the
assessment of entrainment effects. Simileirly, knowledge of the post-larval juvenile stage is also important.
The mortality of these fish is intermediate between that of larvae and adults and may play an important
part in establishing the success of a year-class. Impingement of juveniles and adults at MNPS has become
less of a concern as the installation of fish return sluiceways at Units 1 and 3 has reduced this impact.
Recent decreases in impingement were most likely a result of the general decline in abundance, rather than
its cause.

MNPS Unit 3 began commercial operations in late April of 1986, immediately following the adult
winter flounder spawning season. Therefore, the data gathered up to that time will serve as the baseline
for assessing the full impact of 3-unit operations of MNPS. Future work will focus on larval, juvenile.

117

and adult population parameters. The development of a stochastic population dynamics model for impact
assessment will continue to be an important goal for NUEL.

SUMMARY

1. The life history and population dynamics of the winter flounder has been studied intensively since
1973, due to its importance to the sport and commercial fisheries of Connecticut and potential for
impact. Because winter flounder stocks are localized, most work has concentrated on the population
spawning in the Niantic River to determine if MNPS impacts of impingement and entrainment have
caused or would cause changes in abundance beyond those expected from natural variation.

2. Annual estimates of the Niantic River spawning population have been made since 1976. An abundance
index based on the Jolly (1965) model showed that numbers were relatively stable from 1976 through
1980, increased to a peak in 1982, and subsequently declined to an ll-yr low in 1986. Abundance
determined by trawl CPUE generally paralleled the Jolly index through 1982. The decline in CPUE
was greater through 1985 and less in 1986 than for the corresponding Jolly estimates.

3. Evaluation of both abundance estimators indicated that bias due to failures to meet assumptions and
errors due to low sampling intensity may have affected the Jolly estimates. CPUE values may have
been influenced by changes in sampling methodologies, varying distribution of winter flounder, and
variable annual conditions in the Niantic River.

4. Data from the trawl monitoring program were used with time-based harmonic regression models.
However, most models were unsatisfactory due to insufficient data or a lack of a repetitive pattern of
abundance. High variability in catch, relatively low effort, and the mixture of stocks found at most
stations at certain times of the year make these trawl data difficult to interpret and of limited use in
assessing MNPS impact.

5. Tlirougliout Southern New England, winter flounder abundance has recently declined because of
natural fluctuations and also most likely from increases in commercial fishing.

118

6. Similar to other populations, the average sex ratio for Niantic River winter flounder was about 1.44
females for each male. The length of 50% maturation of females was 26.8 cm, equivalent to age 3
or 4.

7. Most spawning in the Niantic River was completed by early April with annual variations apparently
related to water temperature. Egg production was a function of female size and the length-fecundity
relationship was similar to those reported for other populations. Egg production peaked in 1982 and
has since decreased about 80%.

8. Scales were successfully used to age winter flounder. Mean lengths of age 3 and older females were
significantly larger than those of males. Growth was relatively rapid in early years, but older age
groups overlapped considerably in size. Growth of the Niantic River fish was less than other
populations in the region through age 2, but equaled or exceeded their means at age 3 and older.

9. The von Bertalanfiy model was used to calculate population growth parameters using 1983 length-at-age
data. Loo was determined as 423 and 38 1 mm and K as 0.42 and 0.44 for females and males, respectively.

10. The mean annual survival rate of adults age 3 and older was determined as 0.486 using a catch curve
with samples combined from successive years to reduce bias.

11. As found elsewhere, the winter flounder preyed upon a variety of benthic organisms and algae. Food
items varied by location and reflected bottom type and different benthic communities.

12. The overall rate of return of Petersen disc-tagged winter flounder was 25%. About twice as many
were taken by the sport than the commercial fishery, although less cooperation was probably received
from the latter. Most (70%) of the returns were from local waters and three times as many of the
longer-distance recaptures were made in waters to the east than to the west.

13. Direct tissue isoelectric focusing techniques were used to differentiate stocks of winter flounder. Good
separation was achieved using fish from major estuaries in Connecticut and Rhode Island at least 8
km apart. A second study using fish from areas closer to MNPS showed more homogeneity, with

119

significant intermixing occurring throughout much of the year. The technique could not be used to
separate immature specimens.

14. Several special studies and analyses were conducted to identify possible sampling biases in the larval
winter flounder data base. The results of these studies included reduced larval net extrusion with
202-nm mesh nets compared to 333- and 505-|im nets, increased sample density of larger larvae in
night collections, and changes in sample densities in relation to tidad stage at a station in the lower
portion of the Niantic River. Due to the identified sample biases, much of the offshore data collected
prior to 1980 could not be used to examine the life history of larval winter flounder.

15. Based on the abundance and distribution of smaller larvae, spawning primarily occurred in the Niantic
River. larvae were gradually flushed into Niantic Bay, where larger larvae dominated. The spatial
distribution of larvae within the Niantic River varied from year to year, but generally smaller larvae
were more prevalent in the upper portion of the river and larger larvae in the lower. The lion's mane
jellyfish was identified as an important predator of larval winter flounder.

16. Examination of otoliths from field-collected and laboratory-reared winter flounder larvae indicted that
daily increments were not visible. Based on the length-frequency distribution, most larval mortality
occurred at the time of first feeding (3-4 mm). Transition to the dermersal juvenile stage occurred at
about 6-7 mm.

17. Fight tidal export-import studies were conducted at the mouth of the Niantic River during 1983-85.
The results showed a net export of 4 mm and smaller winter flounder larvae and a net import of 5
mm and larger larvae. Larvae with developed fm rays migrated vertically in response to tidal currents
to reenter the Niantic River and those within the river demonstrated a similar behavior as a retention
mechanism.

18. Abundance of post-larval young-of-the-year peaked in mid-.Iune and stabilized by late July. Young
were most numerous in the lower river during 1983, with similar densities found during 1984 and 1985.

120

19. Growth of young in the lower river was significantly greater than at stations upriver after mid-June.
Weekly mean lengths in 1983 were about 6 to 8 mm larger than in 1984 or 1985. Monthly survival
estimates of young ranged from 0.552 to 0.569.

20. Peak abundance of age 1 juvenile winter flounder taken in the Niantic River during the adult surveys
occurred in 1981, with second and third highest CPUE in following years. An U-yr low was found
in 1986. However, in recent years juveniles have been found in more areas throughout the river and
in Niantic Bay during the time of the surveys. This variation in distribution makes the estimation of
juvenile abundance less certain than that of adults.

21. About two-thirds of the total number of winter flounder impinged on the traveling screens of MNPS
were taken in winter. Before 1 984, annual estimates usually ranged from 4 to 1 0 thousand with winter
storms accounting for large proportions of most annual totals.

22. Sex ratios and reproductive condition of impinged fish differed from fish taken in the river. The
predominance of males and of gravid females in the collections indicated that at times impingement
was related to behavior of winter flounder.

23. A fish return sluiceway was installed at MNPS Unit 1 in December of 1983 and studies showed that
survival of returned winter flounder would be considerable (ca. 80-90%). This greatly reduces the
impact of impingement on the winter flounder.

24. Entrainment sampling has been conducted since 1976. A majority (>60%) of the winter flounder
larvae entrained were 5 mm and larger. The greatest entrainment densities occurred from mid-April
through May. Based on the median annual entrainment density, three years were low (1977-79), four
years were high (1976, 1980-83), and the remaining years were intermediate. Annual entrainment was
related to total egg production in the Niantic River and the length of time a larva was susceptible to
entrainment was related to water temperature.

25. The effects of entrainment on larval winter flounder were examined in the laboratory and field, larvae
5 mm and larger were able to survive a AT of 13° C for up to 9 h. The estimated critical thermal

121

maxmium was approximately 24° C. A mortality study showed that about 80% of Stage 4 larvae
entrained would have survived entrainment.

26. Impact assessment was addressed using a deterministic model developed by the University of Rhode
Island. The model, subdivided into hydrodynamic, concentration, and population submodels, predicted
a 5 to 6% decrease in the Niantic River population after 35 yr of MNPS operations. Based on the
initial assumptions, the model results were probably conservative. A new stochastic population
dynamics model, which takes into account the natural variability in the recruitment process, is currently
under development at NUEL and will provide a more realistic estimate of potential losses.

27. To date, there is no evidence that MNPS has significantly affected the local winter flounder population.
Variability in annual abundance appears to be related to natural events and has been noted throughout
the region. Future work at NUEL will focus on the early life history stage, including estimates of
larval mortality, which is critical to the understanding and estimation of any deleterious effects of MNPS.

122

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134

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135

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138

Appendix Weekly catch data used for estimating population abundance of Niantic River

I. winter flounder during 1976.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1975

(week marked)
12 3 4 5 6 7

recap

1

3-1

1,352

329

1,021

2

1,023

18

-

-

2

3-8

2,379

690

1,670

19

1,689

16

40 -

40

3

3-15

1,292

283

1,004

5

1,009

42

22 64 -

86

4

3-22

1,617

627

982

8

990

28

15 42 36 -

93

5

3-29

1,283

428

853

2

855

9

6 19 13 19 -

57

6

4-5

1,496

450

949

97

1,046

10

8 16 5 24 33 -

86

7

4-12

1,379

1,372

...

7

1,023

11

7 11 6 10 22 35 -

91

Total

10,798

4,179

6,479

140

7,635

131

98 152 60 53 55 35 -

453

Appendix The 1976 abundance estimate of winter flounder larger than 15 cm during the

11. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

((D)

of <D

(B)

of B

3-1

0.663

0.093

3-8

28,596

5,870

0.937

0.142

-1,411

5,474

3-15

25,353

4,511

0.578

0.110

4,292

2,535

3-22

18,939

3,524

0.527

0.102

11,116

3,373

3-29

21,094

4,286

0.728

0.164

4,148

3,012

4-5

19,514

4,371

Abundance ii

(A'2
idex =

2
errors = ^

+

A^3 + ^4)

3

21,795

±2 standard

VarNj + VarNj + VarN^

±4,768

139

Appendix Weekly catch data used for determining population abundance of Niantic River winter

III. flounder during 1977.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1975-76

(week marked)
12 3 4 5 6

recap

1

3-7

616

91

486

39

525

8

-

-

2

3-14

1,975

925

986

64

1,050

6

9 -

9

3

3-21

2,219

1,242

916

61

977

7

13 35 -

48

4

3-28

1,596

834

762

0

762

4

1 23 22 -

46

5

4-4

971

267

587

117

704

7

2 18 26 35 -

81

6

4-11

1,536

1,535

-

1

907

6

5 9 22 21 16 -

73

Total

8,913

4,894

3,737

282

4,925

38

30 85 70 56 16 -

257

Appendix The 1977 abundance estimate of winter flounder larger than 15 cm during the spawning

IV. period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

(<D)

of <D

(B)

of B

3-7

0.520

0.119

3-14

29,470

11,666

0.656

0.110

-2,874

7,554

3-21

16,425

3,462

0.694

0.124

7,895

3,496

3-28

19,245

4,097

1.157

0.331

-3,383

4,015

4-4

18,879

5,429

Abundance ii

{N2
idex =

2
errors = —

-1-

N3 + N4)
3

18,183

± 2 standard

VarN2 + VarNj + VarN^

±5,088

140

Appendix Weekly catch data used for determining population abundance of Niantic

V. River winter flounder during 1978.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1975-77

1

(week marked)
2 3 4 5 6 7 8

recap

1

3-6

108

40

68

0

68

3

-

.

2

3-13

321

96

189

36

225

13

0

0

3

3-20

1,083

647

436

0

436

14

0

4 -

4

4

3-27

1,108

576

517

15

532

4

0

0 3 -

3

5

4-3

2,037

992

1,045

0

1,045

15

0

3 20 15 -

38

6

4-10

1,893

842

1,051

0

1,051

14

3

2 8 7 35 -

55

7

4-17

1,973

862

1,111

0

1,111

6

0

6 6 6 34 57 -

109

8

4-24

2,486

2,485

-

1

1,574

13

0

2 1 5 21 33 89 -

151

Total

11,009

6,540

4,417

52

6,042

82

3

17 38 33 90 90 89 -

360

Appendix The 1978 abundance estimate of winter flounder larger than 15 cm during the

VI. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

m

of <D

(B)

of B

3-6 to 3-27

0.476

0.078

4-3

15,733

3,513

0.634

0.096

9,154

3,318

4-10

19,126

3,601

0.442

0.070

543

1,463

4-17

9,000

1,470

Abundance ii

(A^l
idex =

2
errors = ^

4-

A^2 + ^3)
3

14,620

± 2 standard

VarNi + VarN2 + VarN^

± 3, 494

141

Appendix Weekly catch data used for detennming population abundance of Niantic River winter

VII. flounder during 1979.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1975-78

(week marked)
12 3 4 5 6

recap

1

3-12

384

163

221

0

221

3

-

-

2

3-19

1,170

613

554

3

557

15

1 -

1

3

3-26

2,781

1,735

1,046

0

1,046

6

2 4 -

6

4

4-2

2,983

1,674

1,308

1

1,309

3

2 5 43 -

50

5

4-9

3,317

2,379

938

0

938

4

3 5 27 51 -

86

6

4-16

1,383

1,381

2

670

4

1 1 20 26 50 -

98

Total

12,018

7,945

4,067

6

4,741

35

9 15 90 77 50 -

241

Appendix The 1979 abundance estimate of winter flounder larger than 15 cm during the

VIII. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error

of

of survival

error

joining

error

(N)

N

(<D)

of <D

(B)

of B

3-12 to 3-26

0.559

-

4-2

26,658

-

0.433

-

-793

-

4-9

10,760

-

Abundance

(^1
index =

+

T

N2)

18,709

142

Appendix Weekly catch data used for determining population abundance of Niantic River winter

IX. flounder during 1980.

Week Date- Total No. No. No. No. Recaps Recaptures

no. week of catch unmrk'd marked removed exam'd 1977-79 (week marked)

12 3 4 5

1 3-17 1,288 646 642 0 642 8 -

2 3-24 3,007 1,806 1,151 50 1,201 24 28 -

3 3-31 3,756 2,586 1,170 0 1,170 4 18 47 -

4 4-7 3,026 1,675 1,350 1 1,351 6 13 50

5 4-14 2,362 2,361 - 1 1,216 10 15 36
Total 13,439 9,074 4,313 52 5,580 52 74 133

67 -
52 107
119 107

Total
recap

28
65
130
210

433

Appendix The 1980 abundance estimate of winter flounder larger .than 15 cm during the spawn-

X. ing period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

(O)

of<t)

(B)

of B

3-17

0.664

0.102

3-24

18,276

4,293

0.766

0.096

7,393

3,969

3-31

21,345

3,542

0.624

0.085

1,536

2,116

4-7

14,856

2,146

Abundance ij

. (A^i
idex =

2
errors = v

-1-

^2 + ^3)

3

18,159

±2 standard

VarN^ + VarN2 + VarN^

±3,976

143

Appendix Weekly catch data used for estimating population abundance of Niantic River

XI. winter flounder during 1981.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1977-80

(week marked)
12 3 4 5 6 7

recap

1

3-2

2,679

1,566

1,111

2

1,113

11

-

-

2

3-9

2,605

1,553

975

77

1,052

10

36 -

36

3

3-16

2,433

1,560

870

3

873

4

24 29 -

53

4

3-23

2,757

1,729

1,028

0

1,028

2

15 22 32 -

69

5

3-30

2,168

772

1,389

7

1,396

14

8 10 13 38 -

69

6

4-4

2,047

689

1,353

5

1,358

4

13 9 17 29 46 -

114

7

4-13

1,742

1,739

-

3

1,309

4

10 11 10 25 29 43 -

128

Total

16,431

9,608

6,726

97

8,129

49

106 81 72 92 75 43 -

469

Appendix The 1981 abundance estimate of winter flounder larger than 15 cm during the

XII. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

(<D)

of <D

(B)

of B

3-2

0.791

0.119

3-9

25,674

5,636

0.681

0.109

2,955

4,122

3-16

20,378

3,932

0.583

0.091

5,963

2,747

3-23

17,842

3,068

1.097

0.171

28,288

7,214

3-30

47,858

8,622

0.757

0.150

-2,988

5,444

4-4

33,218

6,553

Abundance ii

(^2

idex ~

2
errors = ^

-1-

N^ + /V4)
3

28,693

± 2 standard

VarNj + VarN-i + VarNa,

±6,640

144

Appendix Weekly catch data used for estimating population abundance of Niantic River

XIII. winter flounder during 1982.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unnu-k'd

marked

removed

exam'd

1977-81

(week marked)
12 3 4 5 6 7

recap

1

2-22

656

409

244

3

247

15

-

-

2

3-1

1,194

837

355

2

357

12

12 -

12

3

3-8

1,505

326

1,176

3

1,179

34

6 6 -

12

4

3-15

2,294

1,004

1,287

3

1,290

34

3 5 19 -

27

5

3-22

3,021

1,373

1,647

1

1,648

37

4 8 23 42 -

77

6

3-29

1,940

854

1,086

0

1,086

21

2 4 12 26 46 -

90

7

4-5

1,053

1,050

-

3

815

22

3 1 8 8 13 19 -

52

Total

11,663

5,853

5,795

15

6,622

175

30 24 62 76 59 19 -

270

Appendix The 1982 abundance estimate of winter flounder larger than 15 cm during the

XIV. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

(*)

of*

(B)

of B

2-22

1.213

0.335

3-1

8,806

3,458

0.939

0.226

50,683

19,838

3-8

58,950

20,594

0.612

0.102

15,510

15,121

3-15

51,600

12,397

0.754

0.122

-1,142

8,971

3-22

37,768

6,868

0.578

0.110

2,510

3,772

3-29

24,340

4,896

Abundance ii

(^2
idex = — —

2
errors = -r

+

N3 + Ni)
3

49,439

± 2 standard

VarN2 + VarNi + VarN^

±16,666

145

Appendix

Weekly catch data used for estimating population abundance of Niantic River

XV.

winter flounder during 1983.

Week Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no. week of

catch

unmrk'd

marked

removed

exam'd

1977-82

(week marked)
12 3 4 5 6 7

recap

1 2-21

1,461

638

823

0

823

43

-

2 2-28

1,740

962

777

1

778

52

31 -

31

3 3-7

1,633

741

869

23

892

46

15 28 -

43

4 3-14

1,586

718

855

13

868

40

8 22 20 -

50

5 3-21

2,380

1,364

1,015

1

1,016

29

14 14 22 24 -

74

6 3-28

1,969

1,081

857

31

888

33

11 8 14 23 29 -

85

7 4-4

2,014

2,007

-

7

788

31

11 12 9 12 17 19 -

80

Total

12,783

7,511

5,196

76

6,053

274

90 84 65 59 46 19 -

363

Appendix

The 1983 abundance estimate of winter flounder

larger than 20 cm

during the

XVI.

spawning period in

the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

m

of<D

(B)

of B

2-21

0.701

0.108

2-28

14,475

3,312

1.043

0.1.36

13,526

5,473

3-7

28,625

5,970

0.778

0.178

7,542

5,456

3-14

29,799

6,020

0.904

0.246

4,372

5,236

3-21

31,311

6,301

2,065

4,518

3-28

29,632

8,052

Abundance ii

(^2
idex =

2
errors = rr

+ N3 + N4)
3

29,282

± 2 standard

V VarN2 + VarN^ + VarNi

± 7, 042

146

Appendix Weekly catch data used for estimating population abundance of Niantic River

XVII. winter flounder during 1984.

Week

Date-

Total

No.

No.

No.

No.

Recaps

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1977-83

I

(week marked)
2 3 4 5 6 7 8

recap

1

2-14

672

316

351

5

356

31

-

-

2

2-21

1,284

750

534

0

534

53

10

-

10

3

3-1

1,369

693

676

0

677

52

5

9 -

14

4

3-7

1,257

651

605

1

607

45

5

14 14 -

33

5

3-13

740

348

391

1

393

20

1

3 9 4-

17

6

3-20

1,609

1,021

588

0

588

23

6

5 8 9 8-

36

7

3-27

1,049

453

595

1

598

23

2

5 6 11 9 12 -

45

8

4-3

1,074

1,070

-

4

543

16

2

6 5 5 8 6 10 -

45

Total

9,054

5,302

3,740

12

4,296

263

31 42 42 29 25 18 10 -

197

Appendix The 1984 abundance estimate of winter flounder larger than 20 cm during the

XVIII. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

((D)

of<D

(B)

of B

2-14

0.793

0.198

2-21

14,955

5,904

0.997

0.217

23,912

12,380

3-1

38,815

12,801

0.849

0.206

-10,076

10,144

3-7

22,864

6,244

0.667

0.175

10,924

5,213

3-13 to 3-20

26,167

6,785

0.912

0.339

2,028

5,536

3-27

25,900

9,803

Abundance i

(^2
index =

1 errors = ^

-1-

Nj + /V4)
3

29,282

± 2 standard

VarN2 + VarNj + VarN^

±10,518

147

Appendix Weekly catch data used for estimating population abundance of Niantic River

XIX. winter flounder during 1985.

Week

Date-

Total

No.

No.

No.

No.

Recap.

Recapt)

ares

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1981-84

(week marked)

recap

1

2

3 4

5

6 7

1

2-25

959

435

524

0

524

46

-

-

2

3-4

1,173

690

483

0

483

24

8

-

8

3

3-11

1,317

731

580

6

586

23

8

12

-

20

4

3-18

1,273

821

451

1

454

29

4

4

5 -

13

5

3-25

1,824

1.306

514

4

520

17

4

9

15 8

-

36

6

4-1

1,247

769

472

6

478

9

1

6

7 8

16

-

38

7

4-8

1,762

1,759

-

3

626

15

3

3

5 8

13

23 -

55

Total

9,555

6,511

3,024

20

3,671

163

28

34 32 24

29

23 ■

170

Appendix The 1985 abundance estimate of winter flounder larger than 20 cm during the

XX. spawning period in the Niantic River.

Date-

Total

Standard

Probability

Standard

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

m

of<D

(B)

of B

2-23

0.558

0.149

3-4

17,637

7,676

0.829

0.210

4,014

6,963

3-11

18,642

5,912

0.843

0.225

19,518

11,286

3-18

35,236

12,685

0.527

0.147

-7,555

5,796

3-25

11,017

3,020

0.560

0.162

2,573

1,848

4-1

8,739

2,570

Abundance u

(/V2

idex =

2
errors = -r

+ /V3 + /V4)
3

21,632

± 2 standard

^ VarN2 + VarNi + VarN^

± 9, 545

148

Appendix Weekly catch data used for estimating population abundance of Niantic River

XXI. winter flounder during 1986.

Week

Date-

Total

No.

No.

No.

No.

Recap.

Recaptures

Total

no.

week of

catch

unmrk'd

marked

removed

exam'd

1981-85

(week marked)

recap

1

2 3 4 5

6 7

1

2-24

470

178

292

0

292

29

-

.

2

3-3

420

118

298

4

302

33

6

-

6

3

3-10

1,105

630

475

0

475

29

7

11 -

18

4

3-17

954

370

584

0

584

20

6

5 22 -

33

5

3-24

1,002

422

579

1

580

15

4

2 11 27 -

44

6

3-31

1,181

617

562

2

564

17

0

2 5 10 14

-

31

7

4-7

1,055

1,055

-

0

409

10

4

2 3 4 18

12 -

43

Total

6,187

3,390

2,790

7

3,206

153

27

22 41 41 32

12 -

175

Appendix

The

1986 abundanc

:e estimate of winter flounder larger than 20 cm

during the

XXII.

spawning period in

the Niantic River.

Date-

Total

Standard

Probability

Standard-

Calculated no.

Standard

wk. of

number

error of

of survival

error

joining

error

(N)

N

((D)

ofO)

(B)

of B

2-24

0.995

0.286

3-3

14,620

7,202

0.582

0.144

399

3,767

3-10

8,118

2,599

0.658

0.152

3,562

2,160

3-17

8,902

2,375

0.557

0.140

2,779

1,593

3-24

7,735

2,071

1.322

0.463

16,755

7,444

3-31

26,978

10,033

Abundance ii

(A'2
idex =

2
errors = ^

+ N3 + N4)
3

8,252

± 2 standard

7 VarN2 + VarNi + VarN^

± 2, 723

149

Appendix Number of tows by boat during Niantic River adult winter flounder abundance studies

XXIII. from 1976 through 1986.^

Year

Small
craft''

Boat

Mya Hamilton Sisu Sunbeam Northeast I

Northeast II

1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986

106

6

--

--

154

-

-

-

-

67

10

29

-

40

2

51

37

' --

--

--

13

-

-

-

4

—

—

—

75

57
50
63
73
76
89

39
36

72
72
80
90

During four-week period from mid-March through early April.
Various outboard motor-powered boats of similar size.

150

Appendix Number of tows per station during Niantic River adult winter flounder abundance

XXIV. studies from 1976 through 1986.

Year

Station'

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

Entire

study

1

92

285

159

145

166

100

143

56

49

42

39

2

67

63

88

38

30

43

50

21

36

41

36

3

27

3

0

4

-

4

20

3

6

30

20

3

12

23

31

32

39

5

14

2

4

17

1

137

117

-

6

75

41

14

14

11

3

-

-

-

..

7

41

7

16

14

-

-

-

-

8

17

5

2

3

-

-

-

-

51

--

-

64

78

58

58

52

-

--

--

--

33

38

48

70

53

-

-

--

--

-

-

36

49

48

62

54

--

--

--

-- ■

--

--

--

--

--

11

Comparative period

1

54

115

63

62

83

39

27

32

21

24

18

2

26

28

37

17

18

8

12

12

20

24

19

4

4

2

2

3

11

1

7

. 13

17

20

22

5

7

2

1

7

0

59

44

6

21

7

3

4

0

2

-

-

51

-

-

-

-

-

-

36

41

30

27

52

-

-

--

-

-

21

17

29

45

53

--

-

--

-

21

29

29

43

54

--

--

5

Shallow-water stations 3, 6, 7, and 8 dropped after 1979 or 1981. Station 5 subdivided after 1982 into

51-53.

Four-week period from mid-March through April used for calculation of annual CPUE. Excludes

stations 3, 7, and 8 during 1976-79.

151