mu 'ir-m^
CAUFDRNIA
FISH- GAME
"CONSERVATION OF WILDLIFE THROUGH EDUCATION"
California Fish and Game is a journal devoted to the conservation of wild-
life. If its contents are reproduced elsewhere, the authors and the California
Department of Fish and Game would appreciate being acknowledged.
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Please direct correspondence to:
Perry L. Herrgesell, Ph.D., Editor
California Fish and Game
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u
0
V
VOLUME 69
APRIL 1983
NUMBER 2
Published Quarterly by
STATE OF CALIFORNIA
THE RESOURCES AGENCY
DEPARTMENT OF FISH AND GAME
—LDA—
STATE OF CALIFORNIA
GEORGE DEUKMEJIAN. Governor
THE RESOURCES AGENCY
GORDON VAN VLECK, Secretary for Resources
FISH AND GAME COMMISSION
NORMAN B, LIVERMORE, JR., President
San Rafael
WILLIAM A. BURKE, Ed.D., Vice President ABEL C. GALLETTI, Member
Los Angeles Los Angeles
BRIAN J. KAHN, Member ALBERT C. TAUCHER, Member
Santa Rosa Long Beach
DEPARTMENT OF FISH AND GAME
E. C. FULLERTON, Director
1416 9th Street
Sacramento 95814
CALIFORNIA FISH AND GAME
Editorial Staff
Editorial staff for this issue consisted of the following:
Anadromous Fish Kenneth A, Hashagen, Jr.
Inland Fisheries Ronald J. Pelzman
Mahne Resources Robert N. Lea
Wildlife Terry Mansfield
Wildlife Ronald M. Jurek
Editor-in-Chief Perry L. Herrgesell, Ph.D.
CONTENTS
67
Page
Contribution of Cutthroat Trout in Headwater Streams to the
Sea-Run Population John H. Michael, Jr. 68
Benthic Invertebrates of the Earthen Coachella Canal, Califor-
nia Paul C. Marsh and Carolyn R. Stinemetz 11
Osteophagia and Antler Breakage Among Roosevelt Elk
R. Terry Bowyer 84
Concurrent Measurement of Intertidal Environmental Varia-
bles and Embryo Survival for the California Grunion, Leures-
thes tenius, and Atlantic Silverside, Menidia menidia
(Pisces: Atherinidae) .. D. P. Middaugh, H. W. Kohl, and L. E. Burnett 89
Age, Growth, Reproductive Characteristics, and Seasonal
Depth Distribution of the Spotfin Surfperch, Hyperproso-
pon anale Donald M. Baltz and Elaine E. Knight 97
Hazards to Geese from Exposure to Zinc Phosphide Rodenti-
cide Baits James F. Glahn and Larry D. Lamper 105
Ova Fertility Relative to Temperature and to the Time of Ga-
mete Mixing in the Red Abalone, Haliotis rufesens
Earl E. Ebert and Randall M. Hamilton 115
Notes
First Californian Record of the Amarillo Snapper, Lutjanus
argentiventris James E. Phelan 121
Evidence of Birth of a Sea Otter on Land in Central California
Ronald J. Jameson 122
Age and Growth and Length-Weight Relationship for Flathead
Catfish, Pylodictis olivaris, from Coachella Canal, South-
eastern California
Mark S. Pisano, Mary J. Inansci, and W. L. Minckley 124
68 CALIFORNIA FISH AND CAME
Calif. Fish and Came 69 ( 2 ) : 68 -76 1 983
CONTRIBUTION OF CUTTHROAT TROUT IN
HEADWATER STREAMS TO THE SEA-RUN POPULATION ^
JOHN H MICHAEL, JR ^
Snow Creek Research Station
Star Route 2, Box 513
Port Townsend, Washington 98368
This study was designed to assess the contribution of populations of cutthroat
trout in headwater areas of three creeks to anadromous cutthroat populations.
Cutthroat living upstream of permanent barriers to anadromous fish migration in
Snow and Andrews creeks are resident fish which do not migrate to saltwater. In
Salmon Creek, anadromous cutthroat penetrate farther into a watershed than either
steelhead trout or coho salmon and rear sympatrically with resident cutthroat popu-
lations. Consequently, some fish present in these headwater areas will migrate to
saltwater.
Cutthroat present in streams with indefinite or intermittent migration barriers
(e.g., Salmon Creek) may be anadromous. In this study, outmigrant cutthroat
marked in the Salmon Creek study area are probably the progeny of anadromus
cutthroat, not migrants from a resident population. A method to identify resident
and anadromous cutthroat juveniles must be developed in order to more clearly
define the distribution of anadromous cutthroat trout populations.
INTRODUCTION
Coast cutthroat trout, Salmo clarki clarki, range from northern California to
southeastern Alaska (Hart 1973). Within a watershed there may exist sympatric
and allopatric populations of resident and anadromous cutthroat (DeWitt 1954;
Royal 1972; Scott and Crossman 1973; Moring and Lantz 1975; and Jones 1979).
Hartman and Gill (1968) found cutthroat generally occupying smaller tributary
and headwater streams, especially when steelhead trout, 5, gairdneri, were
present in the system. Lowry (1965) found age 0+ cutthroat abundant in small
tributaries within a stream system. Royal (1972), Edie (1975), and Jones (1979)
speculated that resident cutthroat populations may contribute to sea-run popula-
tions. Moring and Lantz (1975) reported a substantial downstream migration of
cutthroat juveniles from an area upstream of two "barrier" falls; however, the
destination of these migrants was undetermined and the nature of the barrier was
poorly defined. Cedarholm and Tagart (Univ. of Wash., research biologists, pers.
commun.) reported anadromous cutthroat adults captured upstream of what
they had previously considered to be an anadromous migration barrier. This
study was initiated to assess the contribution of cutthroat trout inhabiting head-
water areas of three separate streams to the sea-run cutthroat population and
to contribute to the knowledge of the life history of coastal cutthroat, which has
been inadequately studied.
STUDY AREAS
Snow Creek, its main tributary Andrews Creek, and Salmon Creek are located
on the northeastern portion of the Olympic Peninsula and drain into the Strait
' Accepted for publication September 1981.
^ Mr. Michael's current address is; Washington Departnnent of Fisheries, Harvest Management Division, Room 1 1 5
General Administration Building, Olympia, WA 98504.
CUTTHROAT TROUT IN HEADWATER STREAMS
69
of Juan de Fuca (Figure 1). The Washington Department of Game operates
permanent fish traps near the mouths of Snow and Salmon creeks. The traps are
designed to trap all migrating salmonids longer than 300 mm fork length (fl)
year-round and greater than 50 mm fl from March through August. Study areas
were located upstream of 20-m single-step falls in Snow Creek, a steep bedrock
chute with a 6-m drop at an angle of 60° or greater in Andrews Creek, and
upstream from a series of log jams, boulder jams, and cascades in Salmon Creek.
The difference in streambed elevation between the up and downstream sides of
the jams in Salmon Creek was 2-4 m. Preliminary sampling of each study section
failed to find steelhead and coho, Oncorhynchus kisutch, implying a lack of
penetration by anadromous fish.
VICINITY MAP
Strait of
Juan de Fuca
I STUDY AREA
▲ FISH TRAP
MAXIMUM OBSERVED PENETRATION OF
STtELHEAD TROUT AND COHO SALMON
CROCKER LAKE
1 km
FIGURE 1. Location of study areas in Snow, Andrews, and Salmon creeks.
Anadromous cutthroat trout in Snow and Salmon creeks are the late-entry
variety (Johnston and Mercer 1976). Adult cutthroat upstream migration peaks
during January through April. Smolt migration peaks during May but occurs
March through July.
METHODS
Cutthroat from the study areas were collected using a battery powered back-
pack electrofisher. All fish were measured to the nearest millimetre fork length,
fin clipped, and released.
70
CALIFORNIA FISH AND CAME
Cutthroat trout juvenile outmigrants captured in Snow and Salmon creeks'
traps were measured to the nearest millimetre fork length and examined for
marks. A subsample was weighed to the nearest 0.1 g wet weight. Condition
index, K, was calculated by the formula:
l<^ _ 10^ wet weight
Length ^
In 1978 all outmigrants trapped at Snow Creek were given a left maxillary clip
and all outmigrants trapped at Salmon Creek were given a right maxillary clip.
In 1979 a freeze brand was applied to the left side of all outmigrants trapped at
Snow Creek and to the right side of all outmigrants trapped at Salmon Creek.
Cutthroat captured as upstream migrants were measured to the nearest mil-
limetre fork length, weighed to the nearest gram wet weight, examined for
marks, and tagged with a numbered monel-metal mandible tag. The sex and
degree of maturity of the fish were determined by external examination. The
same procedure was employed for downstream migrating adults.
Scale samples were collected from a subsample of cutthroat captured in the
Salmon Creek study area, and a subsample of all cutthroat captured as outmi-
grants at the Snow and Salmon creek traps.
Electrofishing surveys were conducted in Snow Creek in the 1 00 m immediate-
ly downstream from the anadromous barrier during September 1978, to deter-
mine if marked cutthroat from the study area had descended the falls. Electro-
fishing surveys were also conducted downstream from the Snow and Salmon
creeks traps to tidewater during September 1978, to determine if any cutthroat
outmigrants had remained in freshwater.
RESULTS
More than 2,500 cutthroat ranging in size from 33 to 207 mm FL were marked
in the three study streams over a 1-yr period (Table 1 ). Age analysis of fish in
the Salmon Creek study area indicated fish up to 4 yr old were present (Figure
2). While electrofishing during April and May 1978, sexually mature male and
female cutthroat were collected from the Salmon Creek study area. No adult
anadromous cutthroat were found in any study area.
TABLE 1. Number of Cutthroat Trout Marked, Length Range, and Type of Mark for Fish
Marked in Study Areas in Snow, Andrews and Salmon Creeks.
Stream
Date
Number
marked
Length
range (mm)
Mark
Snow Creek system
Snow Creek
Andrews Creek
September 1977
November 1977
788
193
51-207
40-186
Left pelvic
Right pelvic
Total
981
40-207
Salmon Creek
September,
October 1977
April, May 1978
September 1978
810
172
614
40-182
51-200
33-186
Right pelvic
Right pelvic
Right pelvic
Total
Total (all systems)
1,596
2,577
33-200
33-207
CUTTHROAT TROUT IN HEADWATER STREAMS
71
40
30
20
10
5
9
Q
7
6
5
4
3
2
1
10
8
6
4
2
SALMON CREEK UNMARKED OUTMI GRANTS
I
AGE 1
AGE 2
AGE 3
AGE 4
SALMON CREEK MARKED OUTMI GRANTS
SALMON CREEK STUDY AREA
70 80 90 100 UO 120 130 140 150 160
FORK LENGTH (rm)
170 180 190 200 210
FIGURE 2. Ages of cutthroat trout from Salmon Creek, April and May 1978.
No cutthroat marked in either the Snow or Andrews creeks study areas were
captured at the Snow Creek trap. Total cutthroat outmigration for Snow Creek
was small (Table 2). One cutthroat (153 mm fl) marked in the Snow Creek
study area was found immediately downstream of the falls.
TABLE 2.
Numbers, Length, Weight, and Condition Indices (K) for Outmigrant Cutthroat
Trout Captured in the Snow Creek and Salmon Creek Downstream Traps, 1978
and 1979.
Total
Year
Croup
out-
migration
Fork Length (mm)
N Mean Range
Wet Weight (g)
Mean
Location
N Mean
Range
K
Snow Creek
1978
Unmarked
25
25
178
121-298
16 64.3
19.4-194.8
0.8172
1979
Unmarked
37
37
166
128-251
36 47.2
20.8-136.0
0.9143
Salmon Creek
1978
Marked
54
54
130
112-153
40 20.8
14.1- 30.2
0.9463
Unmarked
653
653
134
76-257
425 23.8
3.9-146.8
0.9757
1979
Marked
14
14
143
106-162
14 25.8
12.^ 41.0
0.8942
Unmarked
226
226
143
7^223
196 28.5
7.3-102.1
0.9235
72
CALIFORNIA FISH AND CAME
Cutthroat marked in the Salmon Creek study area were captured during spring
smolt outmigration at the Salmon Creek trap. Marked cutthroat outmigrants were
physically and behaviorally similar to unmarked outmigrants; their length,
weight, condition (K), ages, and migration timing were all similar (Table 2,
Figures 2 and 3).
MARKED OUTMIGRANTS
UJ
APRIL
JUNE
1978
1979
FICURE 3. Timing of capture at downstream migrant trap for outmigrating cutthroat trout in
Salmon Creek, 1978 and 1979.
There was no apparent residualism of study area cutthroat outmigrants in
Salmon Creek as none of the study area outmigrants were captured during
surveys downstream from the trap. Three sea-run cutthroat originally marked in
the Salmon Creek study area were recaptured on their migration from saltwater
to Salmon Creek. One of these fish was later recaptured, spawned out, on its
return migration to saltwater. All Salmon Creek outmigrant groups demonstrated
similar saltwater survival rates of 2 to 7% (Table 3).
CUTTHROAT TROUT IN HEADWATER STREAMS 73
TABLE 3. Survival from Smolting to First Return to Freshwater for Cutthroat Trout
Outmigrations from Snow and Salmon Creeks.
Total First return to upstream trap
Origin Year Croup outmigration 1978-79 1979-80 Total Percent
Snow Creek 1978 Unmarked 25 5 0 5 20
1979 Unmarked 37 N/ A 4 4 11
Salmon Creek 1978 Marked 54 1 1 2 4
Unmarked 653 21 4 25 4
All Salmon Ck. 707 22 5 27 4
1979 Marked 14 N/A 1 1 7
Unmarked 226 N/A 5 5 2
All Salmon Ck. 240 N/A 6 6 3
DISCUSSION
Andrew and Geen (1960) report on the survival rates of various species of
trout and salmon smolts passing over the spillways of 18 to 90 m high dams.
Survival rates ranged from 36-98%. The Washington Department of Fisheries
regularly stocks coho salmon in streams where the resulting smolts have passed
successfully over barriers of greater heights than those on Snow and Andrews
creeks (T. Flint, Wash. Dept. of Fisheries biologist, pers. commun.). If there was
a migration of cutthroat from the Snow Creek study area, it was expected that
enough of the fish would have survived the passage over the falls and instream
predation and have arrived at the trap. Outmigration of smolts from Andrews
Creek is complicated by the presence of Crocker Lake downstream from the
barrier. A trap operated on the inlet to the lake during the spring of 1977 trapped
over 200 migrating juvenile cutthroat, one of which passed through the lake and
was captured in the trap on the outlet stream. Whether the other fish were
anadromous and eaten by predators or were adfluvial and remained in the lake
is not known. In any case, no cutthroat marked in the study areas of Snow and
Andrews creeks migrated to saltwater. Brannon (1967), Northcote, Williscroft,
and Tsuyki (1970), and Raleigh and Chapman (1971 ) have discussed the influ-
ence of inheritance on salmonid migration patterns with the basic movement
pattern being an inherited characteristic. Studies by Miller (1957), Diana and
Lane (1978), and Lestelle (1978) indicate the home range for resident popula-
tions of cutthroat is small. In populations of fish which exist upstream of an
impassable barrier, any fish passing over that barrier is lost to the population.
Unless the fish spawns prior to its downstream migration, the migratory urge is
"lethal," as far as the population is concerned. Fish which leave the headwater
areas of Snow and Andrews creeks are probably random drifters, few in number,
and make no contribution to the anadromous population.
Outmigrant cutthroat which had been marked in the study area of Salmon
Creek are probably the progeny of anadromous cutthroat, not migrants from a
resident cutthroat population. Marked and unmarked outmigrants were similar
in many ways (size, age, migration timing, marine survival rates). In 1978 and
1 979, preseason estimates, obtained by electrofishing, of the number of cutthroat
smolts present in the presumed anadromous zone of Salmon Creek failed to
74 CALIFORNIA FISH AND CAME
indicate the magnitude of the cutthroat outmigration. A large portion of the
unmarked cutthroat likely migrated from reaches of Salmon Creek upstream of
the assumed anadromous barrier, but outside of the study area of this experi-
ment. Although population estimates were not conducted in the Salmon Creek
study area, evidence from experiments being conducted in Penny Creek (Wash-
ington State Game Department 1979), a stream inhabited by resident cutthroat
trout, indicates a rather stable population biomass and stable numerical popula-
tions of age one and older fish. The stability in numbers of age 1 fish present in
October and age 2 and older fish present the following April suggests that if there
is migration from a resident population, it should be stable from year to year
since the numerical decline is stable. Instead, the number of marked outmigrants
declined from 1978 to 1979. A more probable explanation of the migration of
marked cutthroat from the study area to saltwater is that during the spawning
migrations of 1975-1976 and 1976-1977, adult anadromous cutthroat were able
to negotiate what we had considered to be a migration barrier. Cedarholm,
Martin, and Osborne (Univ. of Washington, research biologist, pers. commun.)
have all observed anadromous cutthroat in reaches of streams thought to be
inaccessible to them.
The evidence implies that the "barrier" in Salmon Creek is intermittent or
non-existent and cutthroat migrating from the study area to saltwater were the
progeny of anadromous parents. Because no adult anadromous cutthroat were
captured in the study area of Salmon Creek, it cannot be proven that sea-run
fish actually spawned in the study area during the study period. Marine survival
rates measured for Salmon Creek cutthroat are substantially lower than the 20
to 40% reported by Giger (1972) for an unfished population and 17% reported
by Jones (1978) for a population considered to be overexploited. It is very
difficult to detect anadromous cutthroat adults in small streams (J. Johnson,
Wash. Dept. of Game biologist, pers. commun.). This difficulty, plus the poor
return rates which resulted in small numbers of adults in the stream, made it very
unlikely that any anadromous adults would be located during surveys in the
study area, even if they were present.
The existence of sympatric spawning populations of resident and anadromous
cutthroat may lead to some interbreeding; it is not known what effect this would
have on the migratory patterns of the offspring. Interbreeding may allow the
genes which determine migration patterns to remain in the population and be
expressed in the progeny upstream of a newly-created migration barrier. Unless
anadromous spawners re-invade the area or the fish spawn prior to migration,
the genetic basis for migration will be removed from the population as each
migrant passes over the barrier. The final result will be the evolution of a resident
population of cutthroat trout.
In the absence of a permanent migration barrier, it should be assumed anadro-
mous cutthroat could be present in a stream. Currently, there is no way to
separate juvenile resident and anadromous cutthroat stocks from each other.
There is a good deal of concern being voiced by research personnel in Washing-
ton (Johnston 1979) as to the depressed state of sea-run cutthroat stocks, espe-
cially in those areas of Puget Sound and the Strait of Juan de Fuca most
accessible to anglers. To determine the status of sea-run cutthroat stocks, a
method must be developed to differentiate them from resident cutthroat stocks.
CUTTHROAT TROUT IN HEADWATER STREAMS 75
Measurements of otolith nuclei (Rybock, Horton, and Koski 1975; and Tippetts
1979) have been used to differentiate resident from anadromous stocks of
rainbow trout and may do the same for cutthroat.
SUMMARY
Cutthroat trout residing upstream of permanent migration barriers in Snow and
Andrews creeks were non-anadromous. Cutthroat residing upstream of apparent
migration barriers in Salmon Creek appeared to be progeny of anadromous
stock, i.e., the "barrier" probably did not stop migration of adult sea-run cut-
throat. Cutthroat present in streams with indefinite or intermittent migration
barriers may be anadromous. It is apparent that to assess the status of sea-run
cutthroat populations, a method of discriminating between juvenile anadromous
and resident cutthroat must be developed.
ACKNOWLEDGMENTS
S. Elle, T. Johnson, J. Tagart, and R. Woodin assisted in the collection and
marking of trout and also provided critical comments and suggestions during the
preparation of this paper. M. Chilcote, J. Johnston, and P. Michael also reviewed
the manuscript and suggested numerous improvements. P. Knudsen provided
age determinations through scale analysis. This study was conducted as part of
a cooperative agreement between the U.S. Fish and Wildlife Service and the
Washington State Game Department.
LITERATURE CITED
Andrews, F.J., and C.H. Geen. 1960. Sockeye and pink salmon production in relation to proposed dams in the
Fraser River system. Int. Pac. Salmon Fish Comm. Bulletin 11, 259 pp.
Brannon, E.L. 1967. Genetic control of migrating behavior of newly emerged sockeye salmon fry. Int. Pac. Salmon
Fish. Comm., Prog. Rept. 16, 31 pp.
DeWitt, J. W., Jr. 1954. A survey of the coast cutthroat trout, Salmon c/ar/t/ c/drAr/ Richardson, in California. Calif.
Fish and Game. 40(3): 329-335.
Diana, J.S., and E.D. Lane. 1978. The movement and distribution of Paiute cutthroat trout, Salmo clarki seleniris,
in Cottonwood Creek, California. Trans. Amer. Fish. Soc. 107(3):444-448.
Edie, B.G. 1975. A census of juvenile salmonids of the Clearwater River basin, Jefferson County, Washington, in
relation to logging. M.S. Thesis, Univ. of Wash., Seattle. 86 pp.
Giger, R.D. 1972. Ecology and management of coastal cutthroat trout in Oregon. Oregon State Game Comm.
Federal Aid to Fish Restoration. Project F-72-R. Final Report. 61 pp.
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180:740
Hartman, G.F., and C.A. Gill. 1968. Distribution of juvenile steelhead and cutthroat trout (Salmo gairdneri And S.
clarki clarki) within streams in southwestern British Columbia. Can., Fish. Res. Bd., J., 25(1):33-48.
Johnston, J. M. 1979. Sea-run cutthroat; Stillaquamish River creel census (1978) and harvest limit recommendations.
Wash. Dept. of Game Progress Report. 26 pp.
Johnston, J.M., and S.P. Mercer. 1976. Sea-run cutthroat in saltwater pens: broodstock development and extended
juvenile rearing. Wash. State Game Dept. Federal Aid to Fish Restoration, Progress Report AFS-57-1. 92 pp.
Jones, D.E. 1978. Life history of sea-run cutthroat trout. Alaska Dept. Fish and Game. Anadromous Fish Studies,
Completion Rept, 1971-1977. Project AFS-42. 18(AFS-42-5-B):78-105.
'.. 1979. Development of techniques for enhancement and management of anadromous cutthroat trout
in southeast Alaska. Alaska Dept. Fish & Game. Anadromous Fish Studies, Annual Performance Rept., 1977-
1978. Project AFS-42. (AFS-42-6-B):69-119.
Lestelle, L.C. 1978. The effects of forest debris removal on a population of resident cutthroat trout in a small
headwater stream. M.S. Thesis, Univ. of Wash., Seattle. 86 pp.
Lowry, G.R. 1965. Movement of cutthroat trout, Salmo c/arAr/c/arAr/ (Richardson), in three Oregon coastal streams.
Amer. Fish. Soc, Trans. 94(4):334-338.
Miller, R.B. 1957. Permanence and size of home territory in stream-dwelling cutthroat trout. Can. Fish. Res. Bd.,
J., 14:687-691.
76 CALIFORNIA FISH AND CAME
Moring, ).R., and R.L. Lanlz. 1975. The Alsea Watershed study: effects of logging on the aquatic resources of three
headwater streams of the Alsea River, Oregon, Part 1 -Biological Studies. Federal Aid to Fish Restoration.
Project AFS-58. Final Report. 66 pp.
Northcote, T.C., S.N. Williscroft, and H. Tsuyki. 1970. Meristic and lactate dehydrogenase genotype differences
in streann populations of rainbow trout below and above a waterfall. Can. Fish. Res. Bd., )., 27:1987-1995.
Raleigh, R.F., and D.W. Chapman. 1 971 . Genetic control in lakeward migrations of cutthroat trout fry. Amer. Fish.
Soc., Trans. 100(1 ):33-40.
Royal, L.A. 1972. An examination of the anadromous trout program of the Washington State Came Department.
Wash. State Came Dept. Final Report. AFS-49. 176 pp.
Rybock, J.T., H.F. Norton, and K V. Koski. 1974. Use of otoliths to separate juvenile steelhead trout from juvenile
rainbow trout. Fish. Bull., 73(3):654-659.
Scon, W.B., and E.). Crossman. 1973. Freshwater fishes of Canada. Fish. Res. Bd. Can. Bull. 184:966 pp.
Tippetts, W.E. 1979. Evidence of successful reproduction of steelhead rainbow trout, Salmo galrdneri gairdnerl. in
the Ventura River, California. Calif. Fish Came, 65(3):177-179.
Washington State Came Department. 1980. Penny Creek coho planting study. Pages 70-84 in. C. Carrison, ed.
Steelhead program progress report, December 31, 1979.
BENTHIC INVERTEBRATES OF COACHELLA CANAL ^^^
Calif. Fish and Came 69 ( 2 ) : 77- 83 1 983
BENTHIC INVERTEBRATES OF THE EARTHEN COACHELLA
CANAL, CALIFORNIA '
PAUL C. MARSH
Center for Environmental Studies
Arizona State University
Tennpe, AZ 85287
and
CAROLYN R. STINEMETZ^
U. S. Bureau of Reclamation
Yuma Projects Office
Yuma, AZ 85324
At least 19 taxa of invertebrates inhabited the Coachella Canal, California, in
October-November 1980, Dominants were Asiatic clam, Corbicula fluminea; a hy-
dropsychid caddisfly, Smicridea utico; oligochaetes, Aelosoma sp. and Chaetogaster
sp.; and chironomid dipterans. Mean densities were from 158 to 3,678 individuals/m^
and biomass was 2.02 to 7.63 g dry wt/m^ in mid-channel and near-shore habitats,
respectively. Invertebrate distributions reflected substrate size and stability, and the
presence of organic matter. Concrete structures supported populations of S. utico
and lepidopteran larvae, Parargyractis confusalis, of 25,000 and 1,500/ m', respective-
ly, far greater than densities of any invertebrate on natural substrates.
INTRODUCTION
Macroinvertebrates of North American canals are poorly known despite the
fact that such systems support substantial fish populations (St. Amant etal. 1974)
that may depend on such animals for food. The U.S. Bureau of Reclamation has
conducted investigations of the biota of the Delta-Mendota canal in western
California (e.g., Prokopovich 1968, Eng 1975), although these data received
limited distribution. Outside the United States, work has been done on life cycles
of euryhaline and marine invertebrates of the Baltic Canal (Schutz 1969), and
molluscs have been studied in the Worchester-Birmingham Canal (Young
1975), and in irrigation canals of Lombardy (Bianchi et al. 1978).
Increasing demands for water transport efficiency in the arid American South-
west has resulted in proposals to line existing earthen canal systems with con-
crete. Conversion from earth to concrete substrate is an immediate
environmental alteration. The biological effects of such alterations are not assess-
able because of a lack of information. This report provides baseline data on
relative species abundance, biomass, and community structure of invertebrates
in the earthen Coachella Canal, southeastern California, during autumn.
METHODS AND MATERIALS
The Coachella Canal (Figure 1 ) delivers Colorado River water for agricultural
irrigation in the Imperial, Coachella, and Indio valleys. The canal has a capacity
of 70.8 m^/sec at the turnout from the All American Canal; this is reduced by
withdrawals to 36.8 m^/sec 137.8 km downflow. Depths range from 1-5 m
(mid-channel) and open-reach width is approximately 20 m. The region consists
of "Colorado Desert" (Jaeger 1957), is mostly below sea level, and lies entirely
within the endorheic Salton Sea basin. In order to reduce water loss through
seepage and to increase transport efficiency, the southernmost (upstream) 78.5
km of canal were re-aligned into a concrete structure in mid-November 1980.
' Accepted for publication November 1 981 .
* Present address: Department of Zoology, Arizona State LIniversity, Tempe, AZ 85287
78
CALIFORNIA FISH AND CAME
0 16
16 kn
10 m>
*Cx
V
%.
All AMERICAN
CANAL,
3 2
^^^^
b.h'
FIGURE 1. Earthen Coachella Canal and southern California location map (inset). Sampling sta-
tions denoted by closed circles.
Nine sampling stations on the earthen canal (Figure 1, Table 1 ) were sampled
by Ekman dredge (0.023 m^) on 23-24 October 1980. Quantitative samples were
collected along both banks and at mid-channel in depths of < 1 to 3 m. Samples
were retained on a 420 jutm-mesh sieve and preserved in 10% formalin. Estimates
of current velocity and qualitative observations of substrate type and aquatic
vegetation were made at each station. Additional observations were made adja-
cent to stations 2, 3, and 7 during 10-13 November, when the earthen canal was
dewatered. Qualitative studies included substrates and vegetation; densities of
biota associated with concrete structures were estimated within a 0.01 m^ quad-
rat.
Laboratory processing included removal of course particles from samples and
examination at magnification of 7X for removal, enumeration, and identification
of organisms. Wet weights of invertebrates (en masse except clams) were
recorded to the nearest milligram after blotting to remove excess water. Weights
of individual Asiatic clams were recorded after removal from valves (clams
>4 mm shell length), or following decalcification in 0.1 N HCL (clams <4
mm). Dry weights were estimated to be 0.1 times wet weight (Winberg 1971 ).
RESULTS AND DISCUSSION
General Characteristics
Substrate was predominately fine to medium sand with sparse, pea-sized
gravel (Table 1 ); silt or clay was in near-shore habitats where emergent vegeta-
BENTHIC INVERTEBRATES OF COACHELLA CANAL
79
tion reduced current velocity. Concrete structures at check drops, siphons, and
bridge crossings provided spatially limited, solid substrate. Water velocity was
relatively uniform (0.3 to 0.7 m/sec) in open reaches, but slower near banks and
immediately upstream from constrictions. Rooted aquatic vegetation was in
water <1.0 m deep, and areal coverage was <5.0%. Emergent macrophytes
were common reed, Phragmites australis, and cat-tail, Typha domingens/s; occa-
sional beds of sago pond weed, Potamogeton pectinatus, and milfoil, Myriophyl-
lum spicatum, were present. Water velocity was lower within and near
vegetation, and substrates in such areas contained particulate organic material
not present in areas of greater current. Attached filamentous algae, Cladophora
glomerata, was only on side-walls and aprons of concrete structures.
TABLE 1. Characteristics of Sampling Stations on the Coachella Canal ^
Substrate characteristics
Station East Mid-channel West
1 Clayey sand, Sand CPOM ', detritus,
pebble sand and subm.
vegetation
2 Sand, CPOM, Sandy clay Sand, CPOM,
pebble detritus
3 Sand Clay Sand
4 Sand, detritus Clayey sand Sand
5 Pebbles, sand Clay Pebbles, sand
6 Sand, FPOM ^ Clayey sand Sand
7 Pebble, sand. Clayey sand Pebble, sand
clay
8 Sandy clay Sand Silt, detritus,
vegetation
9 Sand Sand Sand
' East and west depths less than 1 m, nnid-channel depths 2-3 m; current velocities 0.3-0.7 ni/sec at all stations
except 8W, which was slack.
^ CPOM = coarse particulate organic matter, FPOM = fine particulate organic matter.
Macroinvertebrates
Seventeen taxa of aquatic invertebrates were collected on 23-24 October
(Table 2). Asiatic clam, C. fluminea; oligochaetes, Aelosoma sp. and Cha-
etogaster sp.; chironomid midges; and a hydropsychid caddisfly, 5. iy//co collec-
tively comprised >90% of numbers taken (Table 3). Two species of odonates
{Erpetogomphus compositus, Comphus intricatus) were collected on 10-13
November. Biomass was predominated by C. fluminea, with 5. utico a distant
second (Table 3). Near-shore habitat supported the largest populations and
biomasses, with more than 20 times as many individuals and nearly four times
the biomass as in mid-channel. More than twice as many taxa (17) were
near-shore as in mid-channel (7). Proportions of total individuals within each
predominant taxon was, however, about the same for near-shore and mid-
channel samples (Table 3).
East
Mid-channel
West
515
14110
0
515
0
0
0
515
0
0
14114
22119
6931265
43113
19110
513
182190
96150
80 CALIFORNIA FISH AND CAME
TABLE 2. Mean ( 11 Standard Error) Number per Square Meter of Macroinvertebrates
Collected at East Bank, Mid-Channel, and West Bank Sites in the Earthen Coachella Ca-
nal, 23-24 October 1980.
Site
Invertebrate
Ephemeroptera
Baetis sp
Baetiae, undet. genus
Odonata
Hetaerina americana
Hyponeura lugens
Trichoptera
Smicridea utico
Nectopysche sp
Lepidoptera
Parargyractis confusalis 0 0 71 5
Diptera
Chironomidae 804 1 318
Chrysops sp 0
Non-insecta
Turbellaria 5 1 5
Nematoda 0
Oligochaeta (Aelosoma sp., Chaetogaster sp.) 6271553
Ostracoda 0
Hydracarina 67131
Physidae, undet. genus 515
Corbicula fluminea 10331645
Number of samples 9
Overall mean 3305 1 1133
Total number of taxa 12
TABLE 3. Mean (H Standard Error) Number and Biomass (mg dry wt) per Square Me-
ter, and Percentage (in Parentheses) of Total of Predominant Macroinvertebrates Collect-
ed at Bank Sites (East and West Combined) Compared with Mid-Channel Sites in the
Earthen Coachella Canal, 23-24 October 1980.
Site
48138
4471325
0
14114
0
5±5
0
112194
514
6581454
0
616
0
24115
0
616
76133
245711733
9
9
158 1 56
4050 1 2636
7
15
Invertebrate
Bank
Mid-channel
Trichoptera
Smicridea utico
Number
440 1 150(12)
19 1 10(12)
Biomass
63 1 15(<1)
2 1 1(<1)
Diptera
Chironomidae
Number
625 1 252(17)
45 1 38(28)
Biomass
1315(<1)
1 1 1(<1)
Non-insecta
Oligochaeta
(Aelosoma sp., Chaetogaster sp.)
Number
642 1 346(17)
5 1 5(3)
Biomass
45 124(<1)
<1 10.3(<1)
Corbicula fluminea
Number
1745 1 912(47)
7460 1 4440(98)
74 1 33(47)
Biomass
20101 1100(99 + )
Other Taxa
Number
226 193(6)
15 18(9)
Biomass
44 1 18(<1)
1 1 1(<1)
Overall Mean
Number
3678 1 1394
7625 1 4205
158 1 56
Biomass
2015 1 1101
Total Number of Taxa
17
18
7
Number of Samples
9
BENTHIC INVERTEBRATES OF COACHELLA CANAL
81
Distribution of total organisms and biomass among stations (Table 4) ap-
peared related to substrate (Table 1 ) since highest numbers and biomass were
in habitats containing particulate organics. Greatest density occurred at Station
1 (west bank) where juvenile clams (shell <4 mm) predominated. Greatest
biomass was at Station 8 (west bank) where large clams (shells >l-2 cm)
averaged 1,277/m^ in three replicate samples. Station 8 (west bank) had the
lowest water velocity and silt/organic substrate, and supported two distinct
size-classes of clams, the smaller with mean individual dry weight of 0.01 mg,
and the larger with dry weights of 10-550 mg.
TABLE 4. Total Number per Square Meter and Biomass (mg dry wt in parentheses) of
Macroinvertebrates Collected at 27 Sites (East Bank, Mid-Channel, and West Bank at
Each of Nine Stations) in the Earthen Coachella Canal, 23-24 October 1980.
Site
East Bank
Mid-Channel
West Bank
4692 (185)
0
(0)
24,282
(487)
9643 (586)
430
(10)
1205
(51)
43 (1)
0
(0)
215
(2)
6974 (6117)
0
(0)
0
(0)
4649 (234)
344
(7)
1077
(63)
1506 (23,724)
0
(0)
344
(4)
1765 (104)
258
(8191)
732
(66)
86 (1)
172
(3014)
7306
(66,103)
387 (38,319)
215
(6893)
1291
(49)
3305 (7677)
158
(2013)
4050
(7425)
±1133 ±4619
±56
±1101
±2636
±7335
Station
1
2
3
4
5
6
7
8
9
Mean (±1 Standard Error) per Station.
Oligochaetes were abundant near both shores at Stations 1, 2, and 8, and
chironomids near shore at most stations. Caddisfly larvae were most abundant
at Stations 1, 2, 5, and 7, along the east bank where gravel substrates were
present (Table 1 ) . Mean individual dry weights of these organisms were far less
than that of clams, which largely explains the predominance of clam biomass.
The remaining taxa comprised a small numerical and biomass proportion of
the fauna and had no obvious distributional patterns relative to substrate; they
were notably more abundant near shore than in mid-channel (Table 3).
Concrete surfaces exposed upon de-watering were densely populated by
lepidopteran larvae, P. confusalis, and hydropsychid caddisflies, 5. utico. The
lepidopteran was unexpected since it was rare in quantitative samples (Table 2),
yet densities were estimated at 1,500/m^. These organisms are scrapers and
shredders (Merritt and Cummins 1978), and must have been associated with
microalgae films on concrete surfaces. The caddisfly, which feeds on drifting
materials caught in specially-constructed nets, was even more abundant;
estimated densities were at least 25,000/ m^ and biomass was nearly 2,500
mg/m^
Compared with most lotic systems the invertebrate fauna of the earthen
Coachella Canal was depauperate in terms of taxa represented and numbers of
individuals. For example, Merritt and Cummins (1978) reported densities of
chironomids >50,000/m^ as not unusual in lotic habitats, yet <2,300/m^ were
in quantitative canal samples. The unfavorable environment afforded by shifting
sand bottom undoubtedly explains part of the scarcity of organisms (Hynes
1970). Additional taxa could have been associated with beds of aquatic macro-
2—76875
82 CALIFORNIA FISH AND CAME
phytes; however, qualitative sampling upon de-watering added only two taxa
(the odonates) not previously collected. Seasons and organisnn life histories
have significant influences on organisnn abundance and biomass (Rosenberg
1979) since population numbers are high (mean individual weights are small)
early in the life of a given cohort. In these contexts data presented here must
be considered point estimates that may have little relation to mean annual
standing crops.
Predominant organisms in the canal were either filter feeders (Asiatic clam,
many chironomids, the dominant caddisfly), or sediment-detritus ingesters
(Oligochaeta), while others include predators (Turbellaria, Hydracarina, Heta-
erina, Hyponeura) and collector-gatherers (Baetidae, Nectopsyche, Chrysops).
Organisms which rely on a scraping-type habitat (e.g., the snail) were nearly
absent, or were highly localized in distribution ( P. confusalis) . This suggests that
during autumn production of attached microalgae was low on natural substrates
(sand), and local stands on stable substrates such as concrete were inadequate
to support large populations of dependent invertebrates.
It is notable that mayflies, typically in high population densities, were poorly
represented in the canal fauna, and that aquatic beetles, which inhabit an ex-
ceedingly broad spectrum of habitats, were not found. Seasonal effects may be
important, or possibly the shifting sand substrate largely excluded these taxa.
Certainly the most successful organisms were those which lived within sub-
strates, or which were associated with locally stable substrates (5. utico).
Since biomass in the canal was predominated by filter-feeding organisms (C
fluminea and 5. utico), which rely upon zooplankton, phytoplankton, and fine
organic detritus as food, it is relevant to ask where these foods are derived. Three
potential sources seem likely: i ) in water from the All American Canal; ii ) aeolian
particulate materials; and iii) autochthonous production by plants and animals.
If the first were the case, one would anticipate greater densities and biomass of
filter feeders upstream near the source of water. This did not occur (Table 4).
A choice cannot be made between the other alternatives, but a combination of
those two food sources seems likely.
CONCLUSIONS
The earthen Coachella Canal supported a depauperate invertebrate fauna.
Based upon our observations of stable concrete structures, we expect that
Cladophora and other periphyton will be highly productive on these substrates
in the new canal section and will support high secondary production of associat-
ed grazers and filter-feeders. Burrowers will be habitat-limited until substrate
accumulates through blow-in from the surrounding dune fields. Water clarity
should be enhanced by the virtual elimination of bank erosion and this should
have a positive effect on primary and secondary production. This new canal will
lack cover such as bank holes and vegetation which provide habitat diversity.
Too, concrete canals can be effectively cleaned and this disturbance could
substantially reduce the system's productivity.
LITERATURE CITED
Bianchi, I., A. Freddi, A. Cirod, and M, Marian. 1 978. Faunistic considerations and population dynamics of mollusks
living in irrigation canals in Lombardy. Boll. Pesca Piscic. Idrobiol., 30(2) : 177-206.
Eng, L. L. 1975. Biological studies of the Delta-Mendota Canal, Central Valley Project, California, II. Final Report,
U.S. Bureau of Reclamation, Sacramento, CA. 178 p.
BENTHIC INVERTEBRATES OF COACHELLA CANAL 83
Hynes, H. B. N. 1970. The ecology of running waters. University of Toronto Press, Toronto, Ontario. 555 p.
Jaeger, E. C. 1957. The North American deserts. Stanford University Press, Stanford, CA. 308 p.
Merritt, R. W., and K. W. Cummins. 1978. An introduction to the aquatic insects of North America. Kendall/Hunt
Publishing Co., Dubuque, lA. 441 p.
Prokopovich, N. P. 1968. Organic life in the Delta-Mendota Canal, Central Valley Project, California. Progress
Report, U.S. Bureau of Reclamation, Sacramento, CA. 126 p.
Rosenberg, D. M. (ed.). 1979. Freshyk^ater benthic invertebrate life histories: current research and future needs.
Can., Fish. Res. Bd., J. 36(3) : 289-345.
Schutz, L. 1969. Ecological investigations on the benthic fauna in the Baltic Canal, III. Autecology of vagile and
hemisessile species on piles overgrown with vegetation and animals: macrofauna. Int. Rev. Gesamten Hy-
drobiol., 54(4) : 553-592.
St. Amant, J., R. Hulquist, C. Marshall, and A. Pickard. 1974. Fisheries section including information on fishery
resources of the Coachella Canal study area, in Calif. Department of Fish and Game. Inventory of the fish
and wildlife resources, recreational consumptive use, and habitat in and adjacent to the upper 49 miles and
ponded areas of the Coachella Canal. Report to the U.S. Bureau of Reclamation.
Winberg, G. G. 1971. Methods for the estimation of production of aquatic animals. Academic Press, New York,
NY 175 p.
Young, M. R. 1975. The life cycles of six species of freshwater molluscs in the Worchester-Birmingham Canal.
Malacol. Soc. London., Proc. 41 (6) : 533-548.
84 CALIFORNIA FISH AND CAME
Calif. Fish and Came 69 ( 2 ) : 84-88 1 983
OSTEOPHAGIA AND ANTLER BREAKAGE AMONG
ROOSEVELT ELK
R. TERRY BOWYER '
School of Natural Resources
Humboldt State University
Areata, California 95521
Quantified observations of bone and antler chewing by Roosevelt elk, Cervus
elaphus rooseveiti, were made on Gold Bluffs Beach, Prairie Creek Redwoods State
Park, Humboldt County, California during 1973. Bulls were observed chewing bones
and antlers in June and July, and cows during June through August. Seventeen elk
antlers were measured and sampled for calcium and phosphorus content. Significant
correlations were found between antler size and both phosphorus content and the
calcium:phosphorus ratio. It was suggested osteophagia was in response to calcium
and phosphorus deficiencies in forage plants, and that such inadequacies were
related to antler breakage in bulls. Differences in the mineral intake between domi-
nant and subordinate individuals were related to elk dominance hierarchies, and are
discussed in terms of their adaptive significance.
INTRODUCTION
The consumption of bones and antlers by free-ranging ungulates may be
widespread. Osteophagia has been reported for several cervids (Murie 1935,
Flerov 1952, Banfield 1954, Harper et al. 1967, Dansie 1968, Prior 1968, Kraus-
man and Bissonette 1977), and the consumption of bird eggs (Palmer 1926) as
well as other occasional carnivory by ungulates (Severinghaus 1967, Skoog 1968,
Wormell 1969, Stone and Palmater 1970) may be similar to osteophagia.
The reason generally offered to explain bone and antler chewing is sup-
plementation of a calcium or phosphorus deficient diet. However, with the
exception of Langman (1978), little quantitative information exists on the miner-
als obtained by osteophagia, or the frequency with which this behavior occurs.
This paper provides a quantified description of osteophagia for Roosevelt elk,
Cervus elaphus rooseveiti, and examines the relationship between osteophagia
and antler breakage among bulls.
STUDY AREA AND METHODS
This study was conducted on the Cold Bluffs Beach portion of Prairie Creek
Redwoods State Park, Humboldt County, California. The study area is com-
prised largely of coastal prairie separated from nearby redwood. Sequoia seper-
vlrens, forest by precipitous sandstone cliffs. Red alder, Ainus rubra, groves
surround numerous creeks in the 4-km^ area. The climate is mild, but rainfall
commonly exceeds 200 cm per year. More complete descriptions of the Gold
Bluffs Beach climate and vegetation are available elsewhere ( Harper et al. 1 967,
Franklin, Mossman and Dole 1975, Bowyer 1976). Elk were observed for over
700h between 12 November 1972 and 28 November 1973. Behavioral data were
recorded using an all-occurrences log (Altmann 1974).
The circumference of the main beam for each of 17 antlers was measured
directly above the corona. The total length of each antler was measured along
the main beam from the corona to the tip of the last tine (royal or sur-royal),
and the number of tines recorded. An index of antler size was obtained by
' Mr. Bowyer's current address is: Center of Environmental Sciences, Unity College, Unity, Maine 04988. Accepted
for publication November 1981.
OSTEOPHACI A AMONG ROOSEVELT ELK 85
multiplying antler length by antler circumference and dividing by 1000. This
measurement was used rather than antler weight or density because some
antlers were attached to the skulls of museum specimens. Samples for chemical
analysis were obtained by drilling a small hole through the main antler beam at
the mid-point of its length. Plant and soil samples for chemical analyses were
collected at random from Cold Bluffs Beach in July 1973. Chemical analyses
were performed by the Department of Soils, Water, and Engineering of the
University of Arizona. Antler and plant samples were subjected to a perchloric
acid digestion for calcium and phosphorus determinations (Horwitz 1975). For
the soil sample, calcium was determined by the soluable plus exchangeable
method, while phosphorus was determined using the saturated carbon dioxide
extraction method (Horwitz 1975).
RESULTS AND DISCUSSION
Bulls were observed chewing bones or antlers on six occasions in June and
July, and a cow did so once during August. Osteophagia was observed among
50% of 10 bulls and 5% of 20 cows which comprised the Cold Bluffs Beach
herd. Other researchers observed Roosevelt elk cows chewing bones on eight
occasions in June and July (Severy, Kitchen, and Mandel, Humboldt State Univ.,
pers. commun.) and once during December (Harper et al. 1967). A yearling
male was observed chewing bone in late April (Mandel, Humboldt State Univ.,
pers. commun.). It appeared all bones and antlers chewed were from elk. Those
bones recognized included a scapula, rib, vertebra, lower jaw, and cannon bone.
Bones and antlers were never completely consumed by elk. Three bones and
an antler examined after elk had chewed them all showed areas where small
splinters and chips had been broken away and, presumably, ingested. Elk
chewed bones and antlers with their premolars and molars and often turned the
object in their mouth while chewing. A cow once temporarily lodged a vertebra
in her mouth. The mean length of time elk engaged in osteophagia was 10 min
(SD = 5.8 min, range = 5-20 min, N = 7).
Agonistic encounters between bulls over the possession of bones and cast
antlers were observed on five occasions during June, and accounted for 16%
of observed bull aggression during that month. Aggression over bones or antlers
was not observed in other months. \
Following the 1972 rut, 5 of 10 bulls sustained breaks of the main antler beam.
Severe antler breakage occurred among bulls with small or medium sized ant-
lers, but was not observed in large-antlered males. However, after the 1973
mating season, there were no breaks of the main beam; antler breakage was
restricted to tines. Although the sample was small, a highly significant difference
occurred in the number of bulls with breaks of the main antler beam between
1972 and 1973 (X^ = 6.66, P<0.01, 1 d.f.). Logsden (cited in McCullough 1969)
noted that elk from this area showed little or no antler breakage in 1964. Variabil-
ity among years in which antlers were broken and the occurrence of osteophagia
by bulls just prior to velvet shedding in August, raise the possibility that calcium
and phosphorus obtained by this behavior may be related to antler size and
strength.
Significant positive correlations were found between antler length and antler
basal circumference (r^ = 0.43, P<0.01, 16 d.f.) and between the number of
86 CALIFORNIA FISH AND CAME
antler tines and antler length (r^ = 0.99, P< 0.001, 16 d.f.) (Table 1). The
correlation between antler basal circumference and the number of antler tines
was not significant (r^ = 0.01, P>0.99, 16 d.f.). Since most of the variation in
the number of antler tines was explained by antler length, and number of tines
was significantly correlated with the composite variable antler size (r^ = 0.39,
P<0.05, 16 d.f.), number of tines was eliminated from further analyses.
TABLE 1. Measurements and Mineral Composition of 17 Roosevelt Elk Antlers
Mean SD Range
Length
(cm) %.5 11.2 77.6-121.2
Basal circumference
(cm) 21.1 2.4 16.5-25.4
Tines
(no.) 5.4 0.9 4-7
Calcium content
(%) 19.01 3.02 16.63-30.19
Phosphorus content
(%) 7.00 0.87 5.51-8.95
Calcium: phosphorus
ratio 2.7:1 0.4:1 2.3:1-3.3:1
A significant positive correlation was found between antler size and phospho-
rus content (r^ = 0.26, P<0.05, 16 d.f.), but there was no correlation between
antler size and calcium content (r^ = 0.01, P>0.99, 16 d.f.).
The ratio between calcium and phosphorus, rather than the amount of phos-
phorus per se, may be the critical factor in determining antler size and strength.
Unfortunately, no optimum calcium:phosphorus ratio has been established for
elk antlers. The four largest elk antlers (length X = 1 10.7 cm, SD == 4.5 cm, range
= 100.5-121.2 cm; cjrcumference X = 24.5, SD = 4.3 cm, range = 23.5-25.4
cm; number of tines X = 6.5, SD = 0.5, range = 6-7) were assumed to be the
strongest since main beam breakage did not occur among large-antlered bulls.
These four antlers approximated a calciumiphosphorus ratio of 2.5:1. This value
was assumed to be favorable for antler growth and strength, and all other ratios
were expressed relative to it. When antler size was regressed against the absolute
value of the difference of the calcium:phosphorus ratio of 2.5:1, the inverse
correlation was significant (r^ = 0.26, P<0.05, 16 d.f.), but explained no more
of the variation than did phosphorus content alone. However, antlers from
which the mineral samples were obtained came from specimens collected from
1957-1973, and some variation may have resulted from differences in mineral
availability between years.
Calcium and phosphorus contents of soil from a prairie area on Gold Bluffs
Beach were < 0.001% and 0.103%, respectively. Prairie wedge grass, Spheno-
pholis obtusata, had a calcium content of 0.729% and a phosphorus content of
0.1 03%. The calcium content of red alder leaves was 0.598% and its phosphorus
content was 0.174% . The calcium:phosphorus ratio for prairie wedge grass and
red alder was 7.1:1 and 2.9:1, respectively. The phosphorus content of prairie
wedge grass was identical to the amount of this mineral available in the soil,
suggesting the possibility of low phosphorus availability in some forage species.
Care should be exercised in interpreting these data. The true digestibility of
phosphorus is quite high in domestic ruminants while a considerably smaller
OSTEOPHAGIA AMONG ROOSEVELT ELK 87
portion of calcium is assimilated (Church 1971 ). For instance, a broad range of
calcium:phosphorus values (1:1 to 7:1) are adequate for growth in domestic
cattle and these rations all result in approximately a 2:1 ratio being deposited in
bones (Maynard and Loosli 1969). Data relating mineral intake to the final
chemical composition of elk antlers are unavailable. Nonetheless, the possibility
exists that phosphorus or the proper calcium:phosphorus ratio may be related
to antler size and strength, and that elk may supplement their diet by chewing
bones and antlers. Calcium:phosphorus deficiencies in livestock typically are
corrected by feeding bone meal (Maynard and Loosli 1969).
McCullough (1969) presented the only other information concerning the
mineral composition of Roosevelt elk antlers. He found a mean calcium:phos-
phorus ratio of 1 .9:1 for 5 antler samples collected from Prairie Creek Redwoods
State Parkin 1964. Similarly, the mean ratio for lOtuleelk, C. e. nannodes, antlers
from Owens Valley, California was 1 .9:1 and 5 antlers from the Tupman Reserve
in California yielded a mean ratio of 2.0:1 (McCullough 1969). McCullough
(1969) suggested that tule elk antlers were predisposed to breakage by low
phosphorus levels available in forage, and noted that those elk herds with the
highest proportion of phosphorus to calcium in their antlers seemed less prone
to antler breakage. The significant correlation between antler size and phospho-
rus content for Roosevelt elk supports this hypothesis. Moreover, phosphorus is
often in limited supply on western ranges (Stoddart, Smith and Box 1975).
An inadequate supply of either calcium or phosphorus in an animal's diet may
limit the nutritive value of both minerals ( Maynard and Loosli 1 969 ) . It is unclear
whether phosphorus or the calcium:phosphorus ratio is more important in deter-
mining antler size and strength. X
Roosevelt elk bulls exhibited a linear dominance hierarchy (Bowyer 1976).
High-ranking males of Cervos e/ap/jt/s typically have larger antlers than subordi-
nates, and antler size may be important in the establishment of dominance and
ultimately influence breeding success (McCullough 1969, Lincoln 1972, Topinski
1974, Bowyer 1976, Clutton-Brock et al. 1979). All agonistic interactions
between bulls over possession of bones and cast antlers resulted in subordinates
relinquishing these objects or being driven away from them. Minerals obtained
by this behavior may be important in antler size and strength and perhaps
reproductive success.
Ruminants have high calcium requirements during lactation and phosphorus
is needed for the proper growth of young (Maynard and Loosli 1969, Church
1 971 ) . Elk cows were nursing calves during June and July when bone and antler
chewing was most common, suggesting osteophagia may supplement minerals
needed for lactation.
ACKNOWLEDGMENTS
I would like to thank the personnel of Prairie Creek Redwoods State Park for
their help and friendship during my stay at Gold Bluffs Beach. Humboldt State
University, Prairie Creek Redwoods State Park, and Eureka High School gra-
ciously contributed elk antlers from their collections. I am indebted to T. Adams,
R. Botzler, D. Cahill, R. Mandel and M. Phillips for making arrangements for the
antler sampling and measuring. D.W. Kitchen, D.R. McCullough, K.O. Fulgham,
J. Wehausen, M. Collopy, V. Bleich, and Y. McCullough provided assistance in
preparing this manuscript.
88 CALIFORNIA FISH AND CAME
Literature Cited
Altmann, J. 1974. Observational study of behaviour: sampling methods. Behaviour, 49: 227-267.
Banfield, A.W.F. 1954. Preliminary investigation of the barren ground caribou. Canadian Wildl. Serv., Wildl. Mgmt.
Bull., Ser. 1 nos. 10A & 10B. 79 & 112 p.
Bowyer, R.T. 1976. Social behavior of Roosevelt elk during rut. Unpubl. M.S. thesis, Humboldt State Univ., Areata,
122 p.
Church, D.C. 1971. Digestive physiology and nutrition of ruminants. Nutrition, Vol. 2. DC. Church and Oregon
State Univ. Book Stores, Inc., Corvallis, 801 p.
Clutton-Brock, T.H., S.D. Albon, R.M. Gibson, and F. E. Cuiness. 1979. The logical stag: adaptive aspects of fighting
in red deer (Cervus elaphus L.). Anim. Behav., 27: 211-225.
Dansie, W. 1968. Muntjac pecularities. Deer J. Brit. Deer Soc, 1: 181.
Flerov, C.C. 1952. Musk deer and deer. Fauna of USSR, Mammals. Vol. 1 (New Series). Acad. Sci. USSR. Moscow
and Leningrad. TransL, 1960. Natl. Sci. Foundation, and the Smithsonian Inst. Washington, D.C. 275 p.
Franklin, W.L., A.S. Mossman, and M. Dole. 1975. Social organization and home range of Roosevelt elk. ). Mamm.,
56: 102-118.
Harper, J.A., J.H, Harn, W.W. Bentley, and C.F. Yocom. 1967. The status and ecology of the Roosevelt elk in
California. Wildl. Monogr., 16: 1-49.
Horwitz, W. 1 975. Official methods of analysis of the Association of Official Analytical Chemists. 1 2th Edition, 1 094
P-
Krausman, P.R., and J. A. Bissonette. 1977. Bone chewing behavior of desert mule deer. Southwest Nat., 22:
149-150.
Langman, V.A. 1978. Giraffe pica behavior and pathology as indicators of nutritional stress. ). Wildl. Manage., 42:
141-147.
Lincoln, C.A. 1972. The rote of antlers in the behavior of red deer. J. Exp. Zool. 182: 233-250.
Maynard, L.A., and J.K. Loosli. 1969. Animal nutrition. McGraw-Hill, New York, 613 p.
McCullough, D.R. 1969. The tule elk: its history, ecology, and behavior. Univ. Calif. Publ. Zool., 88: 1-209.
Murie, O.). 1935. Alaskan-Yukon caribou. N. Amer. Fauna No. 54, U.S. Dept. Agric, 93 p.
Palmer, L.J. 1926. Progress of reindeer grazing investigations in Alaska. U.S. Dept. Agric. Bull., 1423, 37 p.
Prior, R. 1968. The roe deer of Cranborne Chase, an ecological survey. Oxford Univ. Press, London, 224 p.
Severinghaus, C.W. 1967. Fishy deer. New York State Conservationist, 22: 40.
Skoog, R. 1968. Ecology of the caribou [Rangiferlarandus grantf) in Alaska. Unpubl. dissertation. Univ. California,
Berkeley, 699 p.
Stoddart, L.A., A.D. Smith, and T.W. Box. 1975. Range management. McGraw-Hill, New York, 480 p.
Stone, W.B., and J.R. Palmateer. 1970. A bird ingested by a white-tailed deer. New York Fish and Game |., 17:
3.
Topinski, P. 1974. The role of antlers in establishment of the red deer herd hierarchy. Acta Theriol., 19: 509-514.
Wormell, P. 1969. Red deer (Cervus elaphus) as a predator on Manx Shearwater (Procellaria puffins). Deer J.
Brit. Deer Soc, 1: 289.
CRUNION AND SILVERSIDE EMBRYO SURVIVAL 89
Calif. Fish and Came 69 ( 2 ) : 89-96 1 983
CONCURRENT MEASUREMENT OF INTERTIDAL
ENVIRONMENTAL VARIABLES AND EMBRYO SURVIVAL
FOR THE CALIFORNIA CRUNION, LEURESTHES
TENUIS, AND ATLANTIC SILVERSIDE, MENIDIA
MENIDIA (PISCES: ATHERINIDAE) ^
D.P. MIDDAUCH
U.S. Environmental Protection Agency
Environmental Research Laboratory
Gulf Breeze, Florida 32561
H.W. KOHL and L.E. BURNETT
University of San Diego
Department of Biology
Alcala Park
San Diego, California 92110
Concurrent daily measurements of environmental variables and embryo survival
were made for two atherinid fishes: the California grunion, Leuresthes tenuis, ob-
served at Blacks Beach, La )olla, California; and the Atlantic silverside, Menidia
menidia, observed at the Point of Pines, Edisto Island, South Carolina. Measurements
were made during April 1980.
Both species spawned in the upper intertidal zone on high tides. L. tenuis eggs
were deposited approximately 4 cm below the beach surface during nighttime.
Subsequent sand deposition buried embryos to a depth of approximately 8 cm where
they were protected from thermal and desiccation stresses. Daily survival of incubat-
ing embryos averaged 97%. M. menidia utilized three spawning substrates: (i) aban-
doned crab burrows, (ii) detrital mats, and (iii) the stems and primary leaves of
cordgrass, Spartina alterniflora. These substrates provided embryos with varying
degrees of protection from thermal and desiccation stresses. Daily survival of em-
bryos located 15 cm deep in abandoned crab burrows averaged 88%. Survival was
less, 76%, at the entrance. Daily survival averaged 94% at the surface of detrital mats
and at the axis of stems and primary leaves of cordgrass. Survival was lower at other
locations on these substrates.
INTRODUCTION
The California grunion, Leuresthes tenuis, and the Atlantic silverside, Menidia
menidia, are rhythmic spawners that deposit their eggs in the upper intertidal
zone (Thompson and Thompson 1919, Middaugh 1981 ). The California grunion
spawns in a sand substrate at the approximate time of new and full moons during
February through August (Clark 1925, Walker 1952). Spawning runs occur at
night and are timed just after the highest high tides during each semilunar period;
subsequent high tides and wave action result in deposition of sand over the
incubating embryos (Thompson and Thompson 1919, Moffatt and Thomson
1978). Approximately 2 weeks after deposition, developed embryos are washed
out of the sand by the next series of high tides of the same or greater height
(Shepard and LaFond 1940). The buried embryos are protected from thermal
stress and remain relatively moist even though they usually are not inundated
for a week or more during incubation (Thompson and Thompson 1919, Walker
1949).
' Accepted for publication December 1981. Contribution No. 221 of The Environmental Research Laboratory, Gulf
Breeze.
90 CALIFORNIA FISH AND CAME
In contrast, the Atlantic silverside deposits eggs on several intertidal substrates
including: (1) abandoned crab burrows along eroding intertidal scarps; (ii)
detrital mats; and (iii) the primary leaves and stems of cordgrass plants, Spartina
alterniflora. Spawning runs occur during daytime high tides. Eggs are deposited
at intertidal elevations where they are usually inundated daily during high tide
(Middaugh, Scott and Dean 1981 ). As with L. tenuis, maximum intensity spawn-
ing runs of M. menidia occur every 2 weeks at the approximate time of new and
full moons. A high tide-sunrise cue has been suggested as the synchronizer for
spawning in M. menidia (Middaugh 1981).
Similarities in the reproductive periodicity of these atherinids, and differences
in the substrates utilized for egg deposition, prompted a study of intertidal
environmental variables and embryo survival of L. tenuis and M. menidia. During
April 1980, daily observations of L. tenuis were made at Blacks Beach, La Jolla,
California and similar observations of M. menidia were made at the Point of
Pines, North Edisto River estuary in South Carolina.
MATERIALS AND METHODS
Study Sites
Blacks Beach, La Jolla, California (lat. 32°52'37", long. n7°15'0") is located
at the base of 50-m high cliffs, about 1 km northwest of the Scripps Institution
of Oceanography pier. During the highest-high tides in April 1 980, only a narrow
section of beach, approximately 2.5 m above mean low water (MLW), was
available as a spawning substrate for L. tenuis. The Point of Pines, North Edisto
River estuary (lat. 32°35'12", long 80°13'48") is located on the northeastern end
of Edisto Island, South Carolina. Three substrates utilized for spawning by M.
menidia, abandoned crab burrows, detrital mats, and cordgrass, S. alterniflora,
all occur along a 1 00-m section of shoreline at an elevation of approximately 1 .8
m above MLW.
Environmental Measurements
Measurements of sand deposition and erosion were made at Blacks Beach.
A wooden stake marked at 1-cm intervals was driven into the substrate at the
location where females were observed depositing eggs on the nighttime high tide
of 1 7 April 1 980. Daily measurements were taken between 1 1 00 and 1 300 Pacific
Standard Time (PST) to establish the pattern of sand deposition and erosion
from 18 to 30 April.
Substrate temperatures were measured at the surface of the beach (0 to 2 cm
deep) and at the estimated depth of incubating embryos each day between 1 100
and 1300 PST. Two replicate measurements were made at 3 to 5 minute intervals
with a YSI telethermometer (mention of trade names does not imply endorse-
ment by the U.S. Environmental Protection Agency or the University of San
Diego) and Model 401 probe.
Percentage moisture (g water/kg sand) at the beach surface and depth of
incubating embryos was determined by taking a 2.5 cm diameter core, extruding
the sample from the coring tube and quickily placing 2.0 cm sections in air tight
plastic bags. Samples were taken to the laboratory, weighed, dried for 24 hours
at 90° C and reweighed.
CRUNION AND SILVERSIDE EMBRYO SURVIVAL 91
A Bailey Instruments Model BAT-4 Laboratory Thermometer with a MT-29/1
microprobe was used to measure substrate temperatures at the following loca-
tions on spawning substrates of M. menidia: (i) abandoned crab burrows at the
lip of the entrance and on the wall 15 cm below the entrance; (ii) detrital mats
on the surface and 4 cm below the surface; (ill) Spartina alterniflora, at the axis
of the stem and primary leaves and 4 cm above it.
Percentage moisture (g water/kg atmosphere) was measured at the locations
outlined above (except 4 cm below the surface of detrital mats) with an Atkins
Model 90023-30 Digital Psychrometer. Replicate measurements of temperature
and moisture were made at 3- to 5-min intervals between 1 100 and 1300 Eastern
Standard Time (EST).
Where appropriate, paired comparison t-tests were used to test for differences
in environmental variables and embryo survival at each location on respective
spawning substrates (Sokal and Rohlf 1969).
Embryo Survival
One or two pods of L. tenuis embryos were collected daily from 18 to 28 April
and microscopically classified as viable or nonviable.
Groups of M. menidia embryos were collected from each substrate location
from 22 to 28 April. The first 30 embryos from each substrate location, observed
with a dissecting microscope, were also classified as viable or nonviable. For the
first few days, eggs of each species were classified as viable or nonviable on the
basis of similar developmental stages for all individuals. Later, the absence or
presence of a heart beat was used to determine viability.
RESULTS
Sand Deposition
There was an overall trend of sand deposition from 18 to 28 April at the
intertidal elevation where L. tenuis eggs were deposited on the night of 17 April.
We estimated that eggs were deposited approximately 4 cm below the beach
surface by females (Figure 1). The nighttime high tide on 28 April caused
moderate erosion (measured on 29 April); many embryos were presumably
washed out of the substrate. Measurements taken on 30 April indicated that a
total washout occurred on the nighttime high tide of 29 April when erosion
reduced the substrate elevation to approximately 11 cm below the developing
embryos (Figure 1 ). An extensive search between 1100-1300 PST on 29 and 30
April failed to yield embryos from the spawning area of 17 April.
Substrate Temperatures
Substrate temperatures where L. tenuis embryos developed were less extreme
than on the surface (Figure 2a). The maximum temperature at the surface was
40° C; at the depth of embryos, 31° C. During the 12-day incubation period,
temperatures at the depth of embryos were significantly lower ( P < 0.001 ) than
at the surface.
Temperatures in abandoned crab burrows utilized as a spawning substrate by
M. menidia were very uniform (Figure 2b). The temperature varied only 6°C at
the burrow entrance during embryo development; and J^C at 15 cm depth.
During the 7-day incubation period temperatures were significantly lower (P <
0.05) at the 15 cm depth than at the burrow entrance. Temperatures were less
92
CALIFORNIA FISH AND GAME
uniform in detrital mats (Figure 2c). The range at the surface was 16°C, max-
imum temperature 40°C. At 4 cm depth, the temperature range was 13°C and
maximum temperature, 34°C. Surface temperatures and those at 4 cm depth in
detrital mats were significantly different (P < 0.01 ). The harshest environment
for embryos was 4 cm above the axis of stems and primary leaves of 5. alterni-
flora, where a maximum temperature of AVC was measured (Figure Id). Tem-
peratures measured at the axis of the stem and primary leaves, and 4 cm high
on 5. alterniflora leaves were not significantly different ( P > 0.05); however, the
maximum temperature for the former location was only 36°C.
Figure 1. Egg deposition and subsequent deposition and erosion of sand from Blacks Beach,
California. Arrow indicates beach surface on 18 April, 1980.
Percentage Moisture
The moisture content of the sand where L. tenuis embryos developed ranged
from 1 to 19% (Figure 2e) . There was no significant difference (P < 0.05) in
the moisture content at the surface (0 to 2 cm deep) and the depth at which
embryos developed.
Atmospheric moisture was uniformly high and similar (P < 0.05) at the en-
trance and at 15 cm depth in abandoned crab burrows where M. menidia
embryos occurred (Figure 2f) . At the surface of detrital mats, moisture was
similar to that measured in abandoned crab burrows (Figure 2g) . No measure-
ments were made at 4 cm depth in detrital mats; however, embryos were always
moist at this location and there was no evidence of desiccation. Embryos devel-
GRUNION AND SILVERSIDE EMBRYO SURVIVAL
93
oping at 4 cm above the axis of stems and primary leaves of 5. alterni flora were
exposed to significantly lower atmospheric moisture (P < 0.001) than those
lower on the plant (Figure Ih).
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Figure 2.
Concurrent daily comparison of environmental variables and embryo survival for the
California grunion, Leuresthes tenuis, and Atlantic silverside, Menidia menidia. L. tenuis:
a) beach surface • •, depth of embryos o o; M. menidia: b) burrow entrance,
• •, 15 cm deep o o,c) detritus surface • ; 4 cm deep, o o, d) primary leaves
• •, 4 cm high o o ; L tenuis: e) beach surface • •, depth of embryos o o ; M.
menidia: f) burrow entrance • ; 15 cm deep o o, g) detritus surface • •, h)
primary leaves • ; 4 cm high o o. L. tenuis, i) buried embryos o o; M.
menidia: j) burrow entrance m 0, 15 cm deep o o, k) detritus surface « •, 4 cm
deep o — o, I) primary leaves 0 0, 4 cm high o o.
Embryo Survival
L tenuis ernbryos showed excellent survival during the 12-day incubation
period, daily X = 97% (Figure 2/). Although wide daily variations occurred,
there was no significant difference (P < 0.05) in the number of surviving M.
menidia embryos taken from the entrance or 15 cm depth in abandoned crab
burrows ( Figure 2j) . During the 7-day incubation period, survival at the entrance
to burrows averaged 76%; at the 15 cm depth, 88%. The number of surviving
embryoson the surface of detrital mats was significantly greater (P < 0.05) than
4 cm deep (Figure 2^), even though temperatures were more rigorous at the
surface of the mat ( Figure 2c) . Finally, embryos deposited at the base of primary
leaves of cordgrass showed significantly better survival (P < 0.01 ) than those
4 cm high (Figure 2/). Very poor survival in daily samples taken from 24 to 28
April probably resulted from extremely high temperatures on 24 April (Figure
Id).
94 CALIFORNIA FISH AND CAME
DISCUSSION
The California grunion spawns fronn February through August, with peak
intensity runs from April to June (Walker 1949, 1952). Shepard and LaFond
(1940) observed that spawning during April to June ensured against the influ-
ence of seasonal cut or fill of the spawning substrate since the primary influence
on sand movement during the period was tidal. Earlier in the year, October to
February, a combination of physical factors resulted in net loss of sand, whereas
later, during July to September, there was net accretion of sand on the beach
adjacent to the Scripps Pier. Timing of spawning runs to coincide with the
highest high tides or a decreasing tidal series on nights following the highest high
tides resulted in deposition of sand over embryos developing in a high-energy
environment.
During the present study, L. tenuis spawned in the sand of Blacks Beach during
the nighttime high tide of 1 7 April, part of the decreasing tidal series. Subsequent
sand deposition buried the embryos to a maximum depth of approximately 8 cm
prior to washout (Figure 1 ). Deposition of sand provided protection from ther-
mal and desiccation stresses and predation. Walker (1949) reported that shore
birds, including marbled godwits, Limosa fedosa, and Hudsonian curlews,
Numenius phaeopus hudsonicus, actively probed the sand in search of L. tenuis
embryos. California gulls, Larus californicus, were observed feeding on embryos
left at the surface by godwits and curlews. It is likely that birds would find pods
of embryos buried to a depth of 7 to 15 cm (Thompson and Thompson 1919
and this study) more difficult to locate than ones 3 to 4 cm deep, the approxi-
mate depth of pods immediately after deposition by females. Recently, Moffatt
and Thomson (1978) reported that L. tenuis egg pods were buried to a depth
of 30 cm. At this depth predation would be highly unlikely. Moreover, ambient
temperatures and the percentage moisture probably would be more uniform,
and less rigorous, than measured in our study.
In contrast, M. menidia spawns in a relatively low-energy estuarine environ-
ment. Spawning runs occur during daytime high tides in the upper intertidal
zone. Although M. menidia occasionally spawns aerially at the water's edge,
release of eggs and milt usually occurs underwater. Precise timing of spawning
to coincide with high tide, when tidal currents are low, probably helped to
ensure egg fertilization since eggs and milt would remain in close proximity for
a longer period during slack high tide than at times when current velocities are
stronger (Middaugh 1981). Recently, Middaugh and Takita (manuscript in
preparation) learned that 10-min old M. menidia sperm were capable of fertiliz-
ing 95% of freshly stri^•ped eggs, but aging of sperm for 20 min reduced the
fertilization rate to only 26%.
L. tenuis embryos monitored during this study showed excellent survival.
Substrate temperatures where embryos developed ranged from 19° to 32° C, X
= 25° C. Thompson and Thompson (1919) measured temperatures from 16 to
27° C at a depth of 7 to 15 cm below the surface; concurrent surface tempera-
tures ranged from 1 5 to 36° C. Our data and those of Thompson and Thompson
(1919) are within the thermal limits for L. tenuis determined in laboratory
studies. Hubbs (1965) reported successful fertilization at temperatures between
12 and 32.5° C; however, hatching occurred only between 14.8 and 26.8° C.
GRUNION AND SILVERSIDE EMBRYO SURVIVAL 95
Similarly, Ehrlich and Farris (1971) observed that L. tenuis embryos hatched
when maintained at 1 4.0 to 28.5° C. Optimum hatching, close to 1 00%, occurred
between 16.0 and 27.0° C, but dropped off rapidly outside this range. Moffatt
( 1 977 ) reported a thermal tolerance limit of 1 8 to 30° C for embryonic develop-
ment and 50% hatching in L. tenuis. Infrequent hatching was noted for embryos
maintained at 14° C. Hatched prolarvae showed decreased total length and
weight when incubated at temperatures above 25° C. Hubbs ( 1 965 ) pointed out
that embryos incubated at temperatures above 19° C would be able to hatch on
the next series of highest tides (approximately 10 to 14 days after they were
fertilized). During our study, these high tides occurred 1 1 and 12 days after eggs
were fertilized, i.e., on the nights of 28 and 29 April. No embryo pods were
found, despite extensive digging, during daytime (1100-1300 PST) on 29 and 30
April.
Thompson and Thompson (1919) and Walker (1952) reported that L. tenuis
embryos remained relatively moist even though they had not been covered by
high tides for several days. In our study, interstitial water ranged from 1 to 19%
(10 to 190 g/ kg sand). Sand at the depth of incubating embryos was damp; no
desiccation was evident.
Temperatures encountered by developing M. menidia embryos were, in gen-
eral, within their thermal tolerance range. Critical thermal maxima (CTM) tests
(Hutchinson 1961 ) conducted with newly fertilized embryos (0-to 1-cell stage)
indicated at least 96% survival up to 38° C, 66% at 39° C, and no survival at 40°
C. In tests with embryos in the closure of blastopore stage ( 1 9-h post-fertilization
at 25° C) and in the onset of circulation stage (48-h post-fertilization at 25° C),
the CTM was 42° C (Middaugh, unpubl. data).
M. menidia embryos developing in abandoned crab burrows and detrital mats
retained their spherical shape; there was no evidence of extreme desiccation.
However, those located 4 cm above the juncture of stems and primary leaves
of S. alterniflora did suffer desiccation and, apparently, the effects of thermal
stress. On 24 April, embroys located 4 cm high on Spartina had been distorted
to a half sphere by desiccation; one side was dimpled. The cumulative effects
of thermal stress, a temperature of 41° C was measured on 24 April, and desicca-
tion resulted in very low survival of embroys sampled on 24 April and subse-
quent days.
In summary, reproductive tactics of Leuresthes tenuis and Menidia menidia
are remarkably similar. Both species spawn intertidally, generally from March
through July. The fortnightly (lunar) spawning periodicity observed in L tenuis
(Walker 1949, 1952) apparently has evolved because of the availability of a
relatively stable spawning substrate during the highest high tides and decreasing
tidal series shortly after new and full moons (Thompson and Thompson 1919).
Additionally, deposition and erosion of spawning substrates during April to June
is influenced primarily by tidal forces; there is not a long term trend of cut and
fill that occurs during other times of the year (Shepard and LaFond 1940).
Menidia menidia also shows a fortnightly periodicity for maximum intensity
spawning runs (Middaugh 1981). However, the coincidence of a high tide at
the time of sunrise every 2 weeks, at the approximate time of new and full
moons, apparently cues the observed periodicity. Deposition of eggs in aban-
doned crab burrows, detrital mats, or on Spartina alterniflora probably occurs
because these substrates provide protection from thermal stress, desiccation,
and predation.
96 ' CALIFORNIA FISH AND CAME
LITERATURE CITED
Clark, F.N. 1925. The life history of Leuresthes tenuis, an atherinid fish with tide controlled spawning habits. Calif.
Fish and Game Comm. Bull., 10:1-51.
Ehrlich, K.F., and D.A. Farris. 1 971 . Some influences of temperature on the development of the grunion, Leuresthes
tenuis (Ayres). Calif. Fish Came, 57(1):58-68.
Hubbs, C. 1965. Developmental temperature tolerance and rates of four southern California fishes, Fundulus
parvipinnis, Atherinops affinis, Leuresthes tenuis, and Hypsoblennuis sp. Calif. Fish Came, 51 (2) ;1 13-122.
Hutchinson, V.H. 1961. Critical thermal maxima in salamanders. Physiol. Zool., 2:92-125.
Middaugh, D.P. 1981. Reproductive ecology and spawning periodicity of the Atlantic silverside, Menidia menidia
(Pisces:Atherinidae). Copeia, 4:766-776.
Middaugh, D.P., C.I. Scott, andJ.M. Dean. 1981. Reproductive behavior of the Atlantic silverside. Menidia menidia
(Pisces:Atherinidae). Environmental Biology of Fishes, 6(%):269-276.
Moffatt, N.M. 1977. Thermal effects on the survival and development of embryonic grunions Leuresthes sardina
and L. tenuis Ph.D. Dissertation. University of Arizona, Tucson. 88 p.
Moffatt, N.M., and D.A. Thomson. 1978. Tidal influence on the evolution of egg size in grunions (Leuresthes,
Atherinidae). Environmental Biology of Fishes, 3(3):267-273.
Shepard, F.P., and E.C. LaFond. 1940. Sand movements along the Scripps Institution Pier. Am. J. Sci., 238:272-285.
Sokal, R.R., and J.F. Rohlf. 1969. Biometry. W.H. Freeman and Co., San Francisco. 776 p.
Thompson, DA., and J.B. Thompson. 1919. The spawning of the grunion. Calif. Fish Game Comm. Bull., 3:1-29.
Walker, B.W. 1949. Periodicity of spawning by the grunion, Leuresthes tenuis, an Atherine fish. Dissertation. Univ.
of Calif., Los Angeles. 166 p.
. 1952. A guide to the grunion. Calif. Fish Game, 38(3):409-420.
SPOTFIN SURFPERCH LIFE HISTORY INFORMATION 97
Calif. Fish and Came 69 ( 2 ): 97-1 04 1 983
AGE, GROWTH, REPRODUCTIVE CHARACTERISTICS,
AND SEASONAL DEPTH DISTRIBUTION OF THE SPOTFIN
SURFPERCH,
Hyperprosopon anale ^
DONALD M. BALTZ
and
ELAINE E. KNIGHT
Department of Wildlife and
Fisheries Biology
University of California
Davis, California 95616
Life history information, based on an analysis of museum material, on the age,
growth, reproductive characteristics, and seasonal depth distribution of the spotfin
surf perch is presented. Females attain mean standard lengths (SL) of 103 mm at age
one, 116 mm at age two, and 121 mm at age three. Males grow more slowly. All
females produce their first brood at age one. Brood size varies from 4 to 20. Brood
size, size of young, and brood wet weight all increase significantly with length of
female. The regression of brood size on age is significant; moreover, when used with
length, age contributes to the prediction of brood size by multiple regression. Spotfin
surfperch occur in offshore waters (depths of 15-64 m) during most of the year but
in summer months females migrate inshore and give birth in shallow waters.
INTRODUCTION
Life history variation within the family Embiotocidae is extensive and involves
differences in longevity, growth, and reproductive characteristics; however,
information on several species is very sparse. To fill one such void for an
uncommon species, the spotfin surfperch, we analyzed several large museum
samples. DeMartini (1969) summarized information on food habits and feeding
morphology of the surfperches. The delicate pharyngeal plates, numerous sharp
teeth, and mouth structure of the spotfin surfperch correlate well with the limited
information on their diet of small fishes, zooplankton, and benthic crustaceans
(Cailliet et al. }^77). This species is now known to range from Blanca Bay, Baja
California to Seal Rock, Oregon ( Miller and Lea 1 972 ) . Other published informa-
tion includes systematic status (Tarp 1952) and distributional records (Gilbert
1915; Roedel 1953; Isaacson and Poole 1965; Miller, Gotshall, and Nitsos 1965;
Wydoski 1969). The purpose of this paper is to report life history information
on the age, growth, reproductive characteristics, and seasonal depth distribution
of this species.
METHODS
All of the fish examined were from museum collections from several locations
and years. A large sample, including 92 gravid females (beach seined by W.I.
Follett and party at San Simeon on 21 July 1948) was loaned by the California
Academy of Sciences (CAS 25471 ) . Other series, beach seined by B. W. Walker
and party at San Simeon on 27 June 1949 (W49-161) and on 20 July 1950
(W50-145), were loaned by the Department of Biology, University of California,
Los Angeles. An additional 73 specimens trawled in Monterey Bay on 6 August
' Accepted for publication January 1982.
98 CALIFORNIA FISH AND CAME
1971 were borrowed from California State University, San Francisco; and 18
specimens trawled near the Farallone Islands on 24 February 1971 were bor-
rowed from the Natural History Museum, Los Angeles County ( LACM 32654-1 ) .
Four Elkhorn Slough specimens were obtained from the teaching collection at
the University of California, Davis. All of the specimens examined had been
preserved in formalin and transferred to alcohol.
Age and growth rates were estimated from annuli on unregenerated scales.
Scales from the left pectoral region were read independently by two observers
on a modified microfiche projector (27.5 X); disputed scales were read by a
third person. Annuli were considered to be false if they were incomplete or
comparable in size to the regenerated portions of adjacent scales, and counts
were accepted only if they were the same on two or more scales. Growth rates
were estimated by back-calculation (Tesch 1971 ). To facilitate comparison with
other studies, linear equations for converting standard length (SL) to fork length
(FL) and total length (TL) were fitted:
FL mm = 5.20 + 1.10 SL mm, r - 0.99, N = 48
TL mm = 10.20 + 1.13 SL mm, r = 0.99, N = 48.
The fecundity of 46 near-term females was determined by counting embryos.
Using stratified sampling, females were selected to cover the range of sizes
available; however, females were excluded if their genital aperture indicated that
they might have aborted young. Females and their young were measured to the
nearest millimetre standard length. The preserved wet weight of the entire brood
was determined to the nearest 0.01 g.
RESULTS
Age and Grov^th
Females attained mean lengths of 103, 116, and 121 mm SL at ages one, two,
and three, respectively. The largest female examined was 128 mm SL. The mean
SL at age, as determined from the age composition of samples collected during
the birthing season and by back-calculation, was obtained (Table 1). Back-
calculation appears to greatly underestimate the length at age of near-term
females. Most of the 1 -year-old females from the San Simeon 1948 collection
had not formed an annulus by 21 July. The summer collections we examined
contained only nine adult males. One-year-old males were 81 mm SL and
2-year-old males were 83 mm SL. Based on these limited data, it appears that
males may grow more slowly and perhaps do not live as long as females.
Brood Characteristics
The number of young in intact broods ranged from 4 to 14 in the samples we
examined. All females of age one or older collected during the summer months
(June-August) carried young or were spent. The smallest 1 -year-old female was
81 mm SL and had a brood of four. Wydoski ( 1 969 ) reported an unusually large
female (161 mm SL; 4 yr) with a brood of 20; however, he did not indicate
whether or not this brood was intact. Simple regression analysis of brood size
on female SL (Figure 1 ) indicates that larger females produce larger broods (y
= -13.8 + 0.21 X, r = 0.873, N = 46, P < 0.01 ). Age does contribute signifi-
cantly to prediction of brood size by multiple regression when used with SL. The
SPOTFIN SURFPERCH LIFE HISTORY INFORMATION
99
multiple regression coefficients were both positive and significant (slope of age:
1.85, P < 0.001; slope of SL: 0.15, P < 0.001 ). The age-specific regression of
brood size was significant (y = 3.0 + 4.1 x, r = 0.79, N = 46, P < 0.01 ). Mean
brood sizes at ages one, two, and three were 7.1, 11.4, and 14, respectively
(Table 2); only one female of age three had an intact brood. The brood wet
weight (g) increased with female SL (Figure 2; San Simeon 1948: y = —30.5 +
0.33x, r = 0.714, N = 29, P < 0.01 ) and accounted for as much as 26% of total
female weight.
TABLE 1. Mean Standard Length (mm) at Age of Female Spotfin Surf perch.
Location
4 Year
Age
N
Mean SL (± 1 SD)
OBSERVED LENGTH AT ACE
1
2
3
San Simeon
1948
1
2
91
1
104.3(3.40)
122
1949
1
2
3
3
16
2
94.3(2.52)
120.4(3.37)
127.5(0.71)
1950
1
2
3
6
1
1
97.3(2.50)
115
125
Monterey Bay
1971
1
2
3
7
13
7
95.3(2.43)
110.2(1.69)
118.4(1.90)
Weighted Mean
1
2
3
107
31
10
103.0
116.0
120.9
Growth Increment
103.0
13.0
4.9
BACK-CALCULATED LENGTH AT AGE
1
2
3
San Simeon
1948
1
2
8
1
85.4(9.35)
101.3
San Simeon
1949
1
2
0
16
107.9(3.20)
3
2
97.5(4.17)
121.5(0.57)
Monterey Bay
1971
1
6
76.4(4.72)
2
13
89.5(13.05)
97.6(1.49)
3
5
78.8(5.52)
91.3(5.27)
104.0(4.29)
Weighted Mean
92.6
98.4
104.0
Growth Increment
92.6
5.8
5.6
TABLE 2. Age-Specific Brood Size of Spotfin Surfperch.
Age
1 2
Sample Means 7.1 11.4
SD 1.51 1.74
N 36 9
3
14
The size of young produced seems to increase with female size; however,
since parturition occurs earlier in older than in younger females in some embi-
otocids these trends may not be valid at parturition (Carlisle, Schott, and Abram-
son 1960). Mean embryo weight (g) increased significantly with female SL (San
Simeon 1948: y = -2.95 + 0.33 SL, r = 0.64, N = 29, P < 0.01). Embryo
100
CALIFORNIA FISH AND GAME
length (Figure 3) also increased with female SL (San Sinneon 1948: y = —25.4
+ 0.51 X, r = 0.633, N = 29, P < 0.01 ). Near-term embryos collected at San
Simeon averaged 27% of the SL of their female parents in June 1948 and 26%
in July 1949 (range 18-34%).
20
15 -
UJ
N
(/)
o
oio
q:
y--l3.8+0.2lx
r-0.873
N-46
P<O.OI
o
Son Simeon 1948
A
1949
D
1950
•
Elkhorn Slough
▲
Monterey Bay 1971
■
Oregon 1968
±
±
±
±
±
±
±
±
±
80 90 100 110 120 130 140 150 160
FEMALE STANDARD LENGTH
FIGURE 1 . The regression of brood size on standard length ( mm ) of female spotfin surfperch. The
Oregon specimen (Wydoski 1969) was not included in the regression.
Seasonal Depth Distribution
A review of depth distribution data for spotfin surfperch suggests that they
occupy offshore waters (15-64 m) during most of the year, but in summer
months schools composed mostly of females move inshore where the young are
born between June and August. Trawl surveys in Monterey Bay indicate that
SPOTFIN SURFPERCH LIFE HISTORY INFORMATION
^01
spotfin surfperch are locally abundant during all seasons at survey depths of 15
to 35 m I Kukowski 1 973; CM. Cailliet, Moss Landing Marine Laboratories, pers.
commun.); however, catch-per-unit-effort appears to decline between 18 and
30 m. Future studies should document sex-specific differences in distribution and
growth rates.
Recent work (Dorn, Johnson, and Darby 1979) comparing the swimming
abilities of pregnant and nonpregnant rainbow surfperch, Hypsurus caryi, indi-
cates that near-term females are unable to achieve the sustained or burst swim-
ming speeds typical of the species; therefore, they must be at a great
disadvantage when trying to avoid predators. This is probably true for all near-
term surfperches, and females of many species move inshore or take refuge in
turbid bays, eelgrass beds, or other complex habitats where they and their young
can better avoid predation. The young can grow more rapidly in a warm,
productive habitat. This tendency helps to explain the skewed adult sex ratios
seen in many inshore collections of embiotocids; however, the slower growth
of male spotfin surfperch suggests that they, like some other male embiotocids,
also suffer higher mortality than females (Warner and Harlan 1982). Thus the
skewed adult sex ratios observed in spotfin surfperch collections are related to
sex-specific differences in distribution and/or mortality.
X
UJ
I-
UJ
^ 5
o
o
o
o:
0 *-V
90 fOO 110 120
FEMALE STANDARD LENGTH
FIGURE 2. The regressions of preserved brood wet weight (g) on female standard length (mm)
in two samples of near-term embryos: open circles, solid line, San Simeon 1948 (y =
-30.5 + 0.33x, r = 0.714, N = 29, P < 0.01); open triangles, dashed line, San
Simeon 1949 (y = -32.7 + 0.35x, R = 0.971, N = 10, P < 0.01).
102
CALIFORNIA FISH AND CAME
35
E 30
o
>-
oc
m
liJ 25
z
<
UJ
20
15 -
^
J-
±
90 100 110 120
FEMALE STANDARD LENGTH
FIGURE 3.
The regressions of mean embryo standard length (mm) on female standard length
(mm) in two samples of near-term embryos: open circles, solid line, San Simeon 1948
(y = -25.4 -I- 0.51x, r = 0.633, N = 29, P < 0.01 ); open triangles, dashed line, San
Simeon 1949 (y = -20.8 -f 0.44x, r = 0.978, N = 10, P < 0.01).
DISCUSSION
The life history of the spotfin surfperch is best understood in comparison to
what is known of other embiotocids. Miller and Lea ( 1 972 ) indicated that spotfin
surfperch attain a maximum size of 152 mm TL; however, a much larger female
(199 mm TL) was reported by Wydoski (1969). Such large individuals are
SPOTFIN SURFPERCH LIFE HISTORY INFORMATION 103
apparently quite rare, and spotfin surfperch are annong the smallest embiotocids
(Miller and Lea 1972). Generally none of the small species studied, including
spotfin surfperch, delay first reproduction beyond age one (Hubbs 1921, Wilson
and Millerman 1969, Hayase and Tanaka 1980). However, under some circum-
stances resulting in poor growth, tule perch, Hysterocarpus traski, and shiner
surfperch, Cymatogaster aggregata, may not produce their first brood at age one
(Cordon 1965, Baltz 1980). The increasing trends in age- and length-specific
reproductive characteristics, including brood size, size of young, and brood wet
weight, found in the spotfin surfperch are typical of most embiotocids. Only the
pink surfperch, Zaiembius rosaceus, does not show a significant increase in
brood size with female length (Baltz, unpubl. data) and has a mean brood size
of 3.5 (Goldberg and Ticknor 1977). However, the lack of an increasing length-
fecundity trend in pink surfperch may be an artifact of capture in deep water
since fecund females tend to abort their young. Other small embiotocids have
brood sizes comparable to spotfin surfperch (Abe 1969, Wilson and Millerman
1969, Hayase and Tanaka 1980); but tule perch, kelp surfperch, Brachyistius
frenatus, (Baltz, unpubl. data), dwarf surfperch, Micrometrus minimus, and reef
surfperch, M. aurora, (Hubbs 1921 ) and one Japanese species, Ditrema viridis,
(Abe 1969, Hayase and Tanaka 1980) greatly exceed the spotfin surfperch in
length-specific fecundity.
Other members of the genus IHyperprosopon differ greatly from spotfin surf-
perch in life history traits. Both the silver surfperch, H. ellipticum, and the
walleye surfperch, /-/. argenteum, are considerably larger species, maximum
length 267 and 305 mm TL, respectively (Miller and Lea 1972). They are also
longer lived and may delay first reproduction. Silver surfperch produce their first
brood at age two and live for 5 years (Wydoski and Bennett 1973). Walleye
surfperch populations near the southern end of their range may attain 170 mm
SL, live for 4 or 5 years, and produce their first brood at age one ( E.E. DeMartini,
Marine Science Institute, U.C. Santa Barbara, pers. commun.); however, females
in central California and Oregon attain a larger size (226 mm SL), have higher
fecundity and may delay reproduction for one or more years (Baltz, unpubl.
data). Based upon the morphological distinctiveness of the spotfin surfperch
from other members of the genus, Hubbs, Follett, and Dempster (1979) use the
scientific name /-fypocriticfithys analis rather than Hyperprosopon anale ( W. I.
Follett, California Academy of Sciences, pers. commun.). Both life history and
morphological variation within the genus deserves further attention.
ACKNOWLEDGMENTS
We thank M. Bradbury, D. Buth, R. H. Rosenblatt, P. Sonoda and C. Swift for
assistance in the acquisition of specimens. G. Cailliet, E. DeMartini and C. Swift
made helpful comments on earlier versions of this paper.
LITERATURE CITED
Abe, Y. 1969. Systematics and biology of the two species of embiotocid fishes referred to the genus Ditrema in
Japan. Japanese Ichthyology, 15(3);105-121.
Baltz, D. M. 1980. Age-specific reproductive tactics and reproductive effort in the tule perch (Hysterocarpus
traskf). Ph. D. dissertation. University of California, Davis. 85 p.
Cailliet, C. M., B. Antrim, D. Ambrose, S. Pace, and M. Stevenson. 1977. Species composition, abundance and
ecological studies of fishes, larval fishes, and zooplankton in Elkhorn Slough. Pages 216-386 in Nybakken, ).,
G. Cailleit, and W. Broenkow, eds. Ecological and Hydrographic Studies of Elkhorn Slough, Moss Landing
Harbor and Nearshore Coastal Waters. Moss Landing Marine Laboratories, 464 p.
104 CALIFORNIA FISH AND GAME
Carlisle, ). C, ). W. Schott, and N. J. Abramson. 1960. The barred surfperch (Amphisticus argenteus Agassiz) in
southern California. Calif. Dept. Fish and Game, Fish Bull. (109):1-79.
DeMartini, E.E. 1969. A correlative study of the ecology and comparative feeding mechanism morphology of the
Embiotocidae (Surf-fishes) as evidence of the family's adaptive radiation into available ecological niches.
Wasmann |. of Biol., 27 (2) :1 77-247.
Dorn, P., L. Johnson, and C. Darby. 1 979. The swimming performance of nine SF>ecies of common California inshore
fishes. Am. Fish. Soc, Trans., 108:366-372.
Gilbert, C. H. 1915. Fishes collected by the United States steamer "Albatross" in southern California in 1904. Proc.
U. S. Nat. Mus., 48:305-380.
Gordon, C. D. 1965. Aspects of the life history of Cymatogaster aggregate. Thesis, Univ. British Columbia. 90 p.
Goldberg, S. R. and W. C. Ticknor, Jr. 1977. Reproductive cycle of the pink surfperch, Zaiembius rosaceus
(Embiotocidae). Fishery Bull., 75(4):882-884.
Hayase, S. and S. Tanaka. 1980. Growth and reproduction of three species of embiotocid fishes in the Zostera
marina belt of Odawa Bay. Bull. Japanese Soc. Sci. Fisheries, 46(9); 1089-1096.
Hubbs, C. L. 1921. The ecology and life history of Amphigonopterus aurora and other viviparous perches of
California. Biol. Bull., 40(4):181-209.
Hubbs, C. L., W. I. Follett, and L. J. Dempster. 1979. List of the fishes of California. Occas. Papers Calif. Acad. Sci.,
133. 51 p.
Isaacson, P. A., and R.L. Poole. 1965. New northern records for the spotfin surfperch, Hyperprosopon anale. Calif.
Fish Game, 51(1):57.
Kukowski, C. E. 1973. Results of the Sea Grant fishes sampling program for the 1971-1972 season. Moss Landing
Mar. Lab. Tech. Publ. 73-6, 48 p.
Miller, D.J., D. Gotshall, and R. Nitsos. 1965. A field guide to some common ocean sport fishes of California. Calif.
Dept. Fish and Game, Marine Resour. Oper., Sacramento. 87 p.
Miller, D. J., and R. N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Dept. Fish and Game, Fish
Bull., (157):1-235.
Roedel, P.M. 1953.Commonoceanfishesof the California coast. Calif. Dept. Fish and Game, Fish Bull., (91):1-184.
Tarp, F.H. 1952. A revision of the family Embiotocidae (the surfperches). Calif. Dept. Fish and Game, Fish Bull.,
(88):1-99.
Tesch, F. W. 1971. Age and growth. Pages 98-130 /WW. E. Ricker, ed. Methods for assessment of fish production
in fresh waters. IBP Handbook No. 3, Blackwell Scientific Pub., Oxford, England.
Warner, R. R., and R. K. Harlan. Sperm competition and sperm storage as determinants of sexual dimorphism in
the dwarf surfperch, Micrometrus minimus. Evolution, 36:44-55.
Wilson, D. C, and R. E. Millerman. 1969. Relationships of female age and size in the shiner perch, Cymatogaster
aggregate. Canada, Fish. Res. Bd., J., 26(9):2339-2344.
Wydoski, R.S. 1969. Occurrence of the spotfin surfperch in Oregon waters. Calif. Fish Game, 55(4):335.
Wydoski, R. S., and D. E. Bennett. 1973. Contributions to the life history of the silver surfperch Hyperprosopon
ellipticum from the Oregon coast. Calif. Fish Game, 59 (3 ):1 78-1 90.
RODENTICIDE BAIT EXPOSURE TO GEESE 105
Calif. Fish and Came 69 ( 2 ) : 1 05- 1 1 4 1 983
HAZARDS TO GEESE FROM EXPOSURE TO ZINC
PHOSPHIDE RODENTICIDE BAITS '
JAMES F. CLAHN' and LARRY D. LAMPER'
U.S. Fish and Wildlife Service
Denver Wildlife Research Center
Fresno, California 93721
Enclosure studies were conducted on Canada Geese, Branta canadensis mofflt-
ti, and White-fronted Geese, Anser albifrons, to evaluate bait acceptance and mortal-
ity of these species from field exposure to 1% zinc phosphide-treated rodent baits
applied at 1, 3, and 10 times the normal application rate of 6.7kg/ha over hay cover
crops. Over alta fescue, Festuca arundinacea, Canada Geese died at all toxicant
levels, but significant weight loss suggested that geese were forced to take bait due
to a lack of sufficient quantity of forage. Over alfalfa, Medicago sativa, Canada Geese
for the most part refused the bait and all survived 4 days of exposure in good
condition. White-fronted Geese over a minimal growth of alfalfa consumed suble-
thal amounts of bait at all treatment levels but survived exposure in good condition.
INTRODUCTION
Zinc phosphide-treated oat groat bait (1%) is commonly used to control
populations of voles Microtus sp. in western hayfields and certain perennial
crops. In the Klamath and Tule Lake basins, on the California-Oregon border,
large populations of geese frequently graze baited fields and may become ex-
posed to lethal quantities of bait. During operational baiting programs goose
mortality has been attributed to this rodenticide (Mohr 1959, Keith and O'Neill
1964); however, these reports suggest exaggerated or unusual exposures of zinc
phosphide bait to geese.
The toxicity of zinc phosphide baits to geese has been demonstrated under
laboratory conditions (Anon. 1962). In these tests. Snow Geese, Chen hyper-
borea, and White-fronted Geese died after being force-fed 200-300 kernels of
1% zinc phosphide oat groat bait. Free-feeding studies, however, indicate that
zinc phosphide-treated baits are repellent and may act as an emetic to certain
species of birds (Siegfried 1968, Mines and Dimmick 1970).
We report here on an evaluation of the potential hazards to two species of
geese from exposure to normal and exaggerated application rates of zinc phos-
phide rodenticide bait under conditions closely simulating those that exist during
operational hayfield baiting programs.
METHODS
All field testing was conducted at the Tule Lake National Wildlife Refuge,
Tulelake, California. Sixteen Canada and 16 White-fronted Geese were tested in
two trials per species of 8 geese each. All geese were wild-trapped adults held
in captivity for at least 1 month before testing and fed a ration of domestic goose
or rabbit pellets and water ad libitum. Canada Geese were exposed to zinc
phosphide baits over two types of hay cover: an alta fescue and alfalfa immedi-
' Accepted for publication February 1982.
* Present address; U.S. Fish and Wildlife Service, Denver Wildlife Research Center, Kentucky Research Station,
Bowling Green, KY 42101.
' Present address: U.S. Fish and Wildlife Service, Denver Wildlife Kcsearch Center, Denver, CO 80225.
106 CALIFORNIA FISH AND CAME
ately after the first hay cutting in |uly 1976. After cutting, both the fescue and
the alfalfa were about 8 cm high. In both White-fronted Goose trials, the birds
were exposed to zinc phosphide bait in alfalfa at the beginning of the growing
season (April 1977), when alfalfa averaged 2.5 cnn high.
For each trial two geese were randomly assigned to each of four (2.4 X 9.8
X 1.2 m) portable enclosures assembled on site from 18 (2.4 X 1.2 m) panels.
The panels were constructed of 1 .9-cm PVC pipe and 2.5-cm poultry netting and
fastened together with 7-cm worm screw-type hose clamps. The enclosures,
readily moved by two people, provided 23.5 m ^ of grazing area for each pair
of geese.
Geese were acclimated to the enclosures for at least 3 days while their general
condition and weight were monitored. During this period the only food provided
to Canada Geese in both trials was the hay cover available on enclosure sites.
Enclosures were moved daily to provide a new source of forage. Water was
provided ad libitum. During pretreatment acclimation, White-fronted Geese
were maintained in a similar manner except that in the first trial, 100 g and 200
g of alfalfa pellets were offered per day in each of two enclosures, respectively,
to assess the need of supplemental feeding over the sparse alfalfa growth.
We formulated the zinc phosphide bait with 1% technical grade (94%) zinc
phosphide on oat groats (hulled oats) using 1% lecithin/mineral oil (1:1 ) as a
binder-adhesive and 0.2% Monastral Green B pigment (E. I. DuPont Nemours
& Co.) as a coloring agent (reference to trade names or commercial suppliers
does not imply endorsement by the U.S. Government). An inert flourescent
particle manufactured by Metronics Associates, Palo Alto, California (Tracerite,
0.1%) was used in the bait to determine the relative amount of bait consumed
by geese. Previous trials on domestic ducks indicated that these particles were
voided within 24 h.
One of three toxicant levels — 1 , 3, and 1 0 times ( 1 X, 3X, and 1 0X ) the normal
application rate of 6.7 kg/ha (the equivalent of 16, 48, and 160g, respectively,
per enclosure site) — was assigned and applied to each site by broadcasting bait
with a hand seeder. The fourth enclosure in each series was used as an untreated
control (OX).
In the second trial with White-fronted Geese the 3X treatment level was
replaced with a 48-g equivalent of twelve 4-g bait spots placed at 1 .5-m intervals
within the enclosure. Enclosures were moved daily over newly applied bait for
4 consecutive days to provide a constant exposure factor and source of forage.
All geese were observed from 3 to 7 days following the last day of bait exposure.
Twenty-four hours after each bait application, body weight and physical
condition of geese were observed and the amount of bait remaining in the
enclosure was noted. A composite sample of goose droppings was collected
from each enclosure site to determine the presence and relative amounts of
Tracerite. Each composite goose dropping sample was hand-mixed and a por-
tion of the sample diluted with an equal amount of distilled water. Using a
disposable pipette, we transferred each diluted specimen to a glass slide and
examined it thoroughly; at least two dilutions were examined to verify the
presence or absence of Tracerite. Tracerite levels were ranked by average num-
ber of particles per field into five categories.
RODENTICIDE BAIT EXPOSURE TO GEESE 107
Geese found dead during trials were weighed, frozen, and shipped to the
Denver Wildlife Research Center for gross pathology and residue analysis. Speci-
mens of gizzard and liver were analyzed for zinc phosphide in the form of
phosphine (PH3) by the gas-liquid chromatography method (Okuno, Wilson,
and White 1975).
Canada Geese surviving field trials were transported to and held in captivity
at the San Joaquin Experimental Range, Madera County, California. Geese were
held 7 days for observation on a ration of goose pellets and water. Following
the observation period we attempted acute oral LD50 determinations for 1%
formulated zinc phosphide bait and with technical grade zinc phosphide using
a method described by Thompson (1947) and Weil (1952). The technical zinc
phosphide was encapsulated in gelatin and introduced into the stomach by
means of a plastic tube. Geese were fasted 4 h before dosing, placed in individual
cages where they were initially observed for 30 min after dosing, and then
observed briefly each day for 7 days after dosing. Two geese were dosed at each
of four levels; 8, 1 2, 1 8, and 28 mg/kg with technical grade zinc phosphide. Tests
with formulated baits were similar except that freshly prepared 1% zinc phos-
phide bait was administered by stomach tubing. Dosage levels were calculated
by grams of bait and administered in equivalent dosages of 12, 18, 28, 42, and
62 mg/kg to each of two geese. Because of the limited number of geese avail-
able, most of the geese surviving the formulated bait test were later used in the
technical material test 60 days later.
RESULTS
Test 1: Canada Geese
During the pretreatment acclimation before Trial 1, the eight geese feeding on
alta fescue stuble lost a mean of 7.3% of their initial body weight (range 0 to
12.5%). However, all geese were healthy and vigorous at the end of the 3-day
period and testing was completed without supplemental feeding. During the
4-day exposure period, test geese continued to lose weight and, based on
Tracerite analysis, consumed lethal and sublethal amounts of zinc phosphide-
treated bait at all toxicant levels (Table 1 ). Evidence of regurgitation was found
in the 3X enclosure 24 h after the first bait application and one of the geese died.
Both 10X geese died 24 h following the second bait application and it appeared
that most of the bait had been consumed. Following the fourth and last bait
application one of the geese in the IX enclosure died although no tracerite was
found in the droppings that day or the previous day. Zinc phosphide residues
of 27 ppm and higher were found in the gizzards of all geese found dead (Table
1 ), but no detectable residues were found in the livers. Gross pathology indicat-
ed that all geese were in varying degrees of emaciation and some congestion
in the heart and lungs was noted.
During 3 days of acclimation geese feeding on an alfalfa stubble (Trial 2) lost
a mean of 1.9% of their initial body weight (range 0 to 6.3%) and testing
commenced without supplemental feeding. Geese lost a mean of 3.8% (0.1 kg)
of their body weight during the 4-day testing period (Table 2). However, the
largest loss was with geese in the control group (0.3 kg) and not the treatment
groups. Tracerite analysis revealed that geese refused the bait under this test
regime except in one instance.
108
CALIFORNIA FISH AND CAME
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RODENTICIDE BAIT EXPOSURE TO GEESE 109
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110 CALIFORNIA FISH AND GAME
Canada geese surviving both trials showed no effect of treatment during the
7-day post-treatment observation period, and all were healthy and vigorous
before the force feeding trials with formulated 1% zinc phosphide bait. Geese
survived dosages of grain bait at 1.2 g/kg and 1.8 g/kg or the equivalent of 12
and 18 mg/kg of zinc phosphide. The first death occurred at 2.8 g/kg, or the
equivalent of 520 kernels of grain. One of two geese dosed at 2.8 g/kg and 4.2
g/kg died, and both geese died at the 6.2 g/kg dosage. The LD » for formulated
bait was calculated with 95% confidence limits at 33.09 ( Range = 1 8.62-58.69 )
mg/kg. Regurgitation of treated grain was noted at all dosage levels, but became
increasingly apparent at the higher levels. All deaths occurred within 18 h after
dosing.
Geese fed by stomach tube with technical zinc phosphide died at a minimum
dose of 8 mg/kg. One of two geese dosed at 8, 1 2, and 1 8 mg/kg died, and both
geese dosed at 28 mg/kg died. The acute oral LD 50 and 95% confidence limits
were calculated at 12.00 (Range = 2.94-48.89) mg/kg. Regurgitation was not
observed during this test. Deaths occurred within 24 h of dosing except at the
8 mg/kg dose which occurred between 48 and 72 h after dosing.
Test II: White-fronted Geese
After 4 days of acclimation to enclosures, White-fronted Geese showed no
improved performance with supplemental feeding; thus supplemental feeding
was eliminated during the testing period. All geese maintained their initial body
weight during the 4-day testing period. Tracerite analysis indicated that geese at
all treatment levels initially consumed sublethal quantities of bait, but consump-
tion appeared to decrease after the first 2 days of exposure (Table 3). All geese
survived 4 consecutive days of exposure without weight loss or unusual effects
except diarrhea, as noted in the 3X and 10X enclosures on day 2 (Table 3). The
second trial with eight White-fronted Geese was a repetition of the first and
geese reacted to spot bait and broadcasted treatments in a similar manner.
Tracerite analysis indicated that bait was consumed in the IX enclosure only on
day 4 and in the spot bait enclosure on days 1 and 4. In the lOX enclosure
sublethal quantities of bait were consumed in decreasing amounts on all 4 days
(Table 3). Again, diarrhea was noted in all treatment enclosures, but no other
adverse effects were observed.
DISCUSSION
Bait acceptance and mortality varied with differences in cover crops, amounts
of standing forage, and bait application rates. Over fescue stubble Canada Geese
consumed bait in large enough quantities to cause mortality at all toxicant levels.
Timing and number of mortalities per enclosure generally corresponded to the
application rate. Continued weight losses before and during treatment suggest
that geese were forced to take the grain bait due to lack of sufficient diet on the
fescue stubble. In contrast, Canada Geese with an ample diet of alfalfa appeared
to refuse bait except in one instance. Some weight loss during this trial did not
appear to be treatment related.
White-fronted Geese, although about half the size of the large Canadas, were
supplied with about one-third the amount of standing alfalfa forage. Under these
conditions the White-fronted Geese appeared to accept sublethal quantities of
bait at all treatment levels, but did not consume sufficient quantities to cause
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1 1 2 CALIFORNIA FISH AND CAME
mortality even at 10 times the normal application rate. After consuming sublethal
quantities of bait, White-fronted Geese appeared to develop an aversion to it
after 2 days of exposure. Subacute doses of toxicant did not appear to have
visible adverse effects, except for diarrhea, on either species. Apparently diar-
rhea was the result of ingesting sublethal amounts of the toxicant and was usually
associated with the presence of tracerite in the feces. This symptom of zinc
phosphide poisoning was observed with domestic fowl and had been attributed
to excessive amounts of bile being excreted (Robertson, Campbell, and Craves
1945).
Tests of technical material and formulated bait force-fed to geese indicated
that these baits are highly toxic and would present a potential hazard to geese
exposed to them. The difference in toxicity between that calculated for technical
material and that for formulated baits is not completely known but may be
associated with the volume of grain necessary to achieve lethal doses resulting
in regurgitation of a portion of the amount of treated grain administered. For this
reason we believe the LD » of 12.00 mg/kg for the technical material on the
Canada Goose to be more accurate. The LD 50 for White-fronted Geese is
reported to be 7.5 mg/kg and for the Snow Goose, 8.8 mg/kg (Anon. 1962).
These indicators of toxicity suggest that all species of geese tested are equally
susceptible to poisoning on a per weight basis. However, the minimum lethal
dose in kernels of 1% treated grain bait was estimated for White-fronted Geese
to be between 200-300 kernels (Anon. 1962), whereas our study with similar
procedures indicates that the minimum lethal dose for the larger Canada Geese
was about 520 kernels of bait. Further studies with 1% formulated bait (Anon.
1962) indicated that White-fronted Geese died when fed between 50-100 ker-
nels of treated bait for up to 5 days. The high gizzard residues in geese found
dead in our study suggest that all died of acute poisoning, although high subacute
doses and emaciation may have contributed to mortality.
Our studies suggest that geese under these testing regimes developed an
aversion to zinc phosphide-treated bait following ingestion of sublethal quanti-
ties. In free-feeding studies with other avian species, Bobwhite Quail, Colinus
virginianus, (Mines and Dimmick 1970), Crowned Guinea Fowl, Numida mela-
gris, and Laughing Doves, Stigmatopelia senegalensis, (Siegfried 1968) initially
avoided zinc phosphide-treated bait except under extreme food deprivation.
Geese, especially White-fronted Geese, did not appear to be as discriminating
as seed-eating birds in avoiding treated bait. In part, this may be due to bait being
inadvertently ingested while geese grazed on alfalfa.
Zinc phosphide is considered to be a strong emetic (Schitoskey 1975). We
were able to document only one instance of regurgitation during field trials,
although, based on force-fed trials, we believe it occurred more frequently. In
studies with Laced-necked Doves, Streptopela chinensis, L. F. Rank (Supervisory
Wildlife Biologist, U.S. Fish and Wildlife Service, pers. commun.) conducted
both free- and force-feeding tests with zinc phosphide-treated oat groats. Caged
doves consistently regurgitated free- and force-fed bait but no other adverse
effects were noted. We speculate that the emetic action of zinc phosphide may
have initially presented geese from ingesting lethal quantities of bait and may
have been responsible for bait aversion developing later in the test. Regardless
RODENTICIDE BAIT EXPOSURE TO GEESE 113
of cause and effect, aversion combined with the emetic properties of zinc
phosphide may have contributed to the survival of geese exposed to treated bait.
Possibly the most important factor contributing to survival of geese was the
availability of a preferred food source. The presence and amount of green forage
(alfalfa) appeared to correspond inversely to the amount of treated bait con-
sumed. Two documented cases of significant mortality to geese are reported
from the Tulelake and Klamath Basins and illustrate the definite hazards to geese
when bait is improperly exposed during periods of relative food scarcity. In 1958
a confirmed loss of 3,676 geese was attributed primarily to 1% zinc phosphide
bait used to control voles during one of the worse vole irruptions ever reported
(Mohr 1959). During February and March alone, about 68,000 kg of bait were
applied, primarily to dormant alfalfa fields, at rates greater than 22 kg/ ha. Me-
chanical broadcasting at excessive application rates was blamed for the mortal-
ity, but the limited forage available after a major vole irruption may have been
an equally important contributing factor. In late October 1963 a loss of 455 geese
was attributed to 1% zinc phosphide-treated bait applied to a barley field in late
July and August at the recommended rate of 7 to 9 kg/ha (Keith and O'Neill
1964). Subsequent burning of the field in October exposed residual bait and
barley to geese. These documented kills indicate that geese will accept lethal
quantities of fine phosphide-treated bait when it is exposed on essentially bare
ground during stress periods.
The overall conclusion from the present study is that zinc phosphide-treated
oat groats pose a relatively low hazard to geese if applied over alfalfa at recom-
mended rates during periods when sufficient foods are available; however, the
initial acceptance of zinc phosphide-treated bait by geese mandates that reason-
able care should be taken to (i) minimize the short- and long-term exposure of
bait, especially in fields where geese are not apt to discriminate between bait
and residual grain (barley stubble or Alta fescue), and (ii) coordinate bait
application with field management regimes insofar as possible until safer rodent
control measures are developed.
ACKNOWLEDGMENTS
We are indebted to R. Fields and E. O'Neill of the Tule Lake National Wildlife
Refuge for their assistance and cooperation in capturing and maintaining the
geese and arranging the test sites. This study was partially funded under contract
with the U.S. Bureau of Reclamation (Contract No. 14-06-200-7231 A).
LITERATURE CITED
Anon. 1962. Economic poisons (pesticides) investigations. Calif. Dep. Fish Came, Wildl. Invest. Lab. Job Compl.
Rep., Pittman-Robertson Wildl. Restoration Proj. No. W-52-B-6. 10 p.
Mines, T., and R. W. Dimmick. 1970. The acceptance by Bobwhite Quail of rodent baits dyed and treated with
zinc phosphide. Proc. Annu. Conf. Southeast Assoc. Game Fish Comm., 24:201-205.
Keith, J. O. and E. J. O'Neill. 1964. Investigations of a goose mortality resulting from the use of zinc phosphide
as a rodenticide. Unpubl. U.S. Fish Wildl. Serv. Rep. Klamath Basin Refuge. 7 p. (Mimeo)
Mohr, J. 1 959. The Oregon meadow mouse irruption of 1957-1 958: Influences of the poisoning program on wildlife.
Fed. Coop. Ext. Serv. p. 27-34.
Okuno, I., R. A. Wilson, and R. W. White. 1975. Determination of zinc phosphide in range vegetation by gas
chromatography. Bull. Environ. Contam. Toxicol., 13(4):392-396.
Robertson, A., J. G. Campbell, and D. Graves. 1945. Experimental zinc phosphide poisoning in fowls. J. Comp.
Pathol. Ther., 55:290-300.
1 1 4 CALIFORNIA FISH AND CAME
Schitoskey, F. 1975. Primary and secondary hazards of three rodenticides to kit fox. J. Wild!. Manage., 39 (2) :41b-
418.
Siegfried, W.R.I 968. The reactions of certain birds to rodent baits treated with zinc phosphide. Ostrich, 39 ( 3 ) : 1 97-
198.
Thompson, W. R. 1947. Use of moving average and interpolation to estimate median — effective dose. Bacteriol.
Rev., 11 (2) :1 15-145.
Weil, C. S. 1952. Tables for convenient calculation of median-effective dose (LD » or ED ») and instructions in
their use. Biometrics, 8(3):249-263.
RED ABALONE OVA FERTILITY 1 1 5
Calif. Fish and Game 69 ( 2 ) ; 11 5-1 20 1 983
OVA FERTILITY RELATIVE TO TEMPERATURE AND TO
THE TIME OF GAMETE MIXING IN THE RED ABALONE,
HAUOTIS RUFESCENS^
EARL E. EBERT AND RANDALL M. HAMILTON *
Marine Resources Branch
California Department of Fish and Game
Marine Culture Laboratory
Granite Canyon, Monterey, California 93940
Five test temperatures (9X, 12°C, ISX, 18"C and 21'C) were selected along with
gamete mixing delays up to 8 h to compare ova fertility in the red abalone, Haliotis
rufescens. At extreme test temperatures (9*0 and 21°C) fertilization success was
poor even at short gamete mixing delay intervals. Optimum fertilization success at
the time of spawning and for extended gamete mixing delay intervals was at ^S'Q.
Overall, fertilization rate was inversely related to the gamete mixing time delay
period.
Comparisons of sperm and ova viability loss, at 15°C, revealed that sperm lost its
viability well in advance of ova.
INTRODUCTION
Induced spawning techniques for the red abalone, Haliotis rufescens, have
been largely perfected by using either heavily ultraviolet irradiated seawater
(Kikuchi and Uki ^974a) or hydrogen peroxide (Morse eta/. 1977). However,
spawnings may lack synchrony and other factors may intercede causing both a
delay in gamete mixing and a loss in gamete viability.
Inoue (1969) and Kikuchi and Uki (19746) reportedon the duration of fertility
of spawned gametes relative to temperature for Japanese haliotid species.
However, such data are lacking for North American haliotids.
The objectives of this paper are (i) to determine gamete viability loss through
time relative to spawning onset and gamete mixing, (ii) to determine the rela-
tionship of temperature to the aforementioned objective, and (iii) to compare
the viability duration of ova and sperm. Such information is considered valuable
to the developing abalone mariculture industry in California.
MATERIALS AND METHODS
Adult red abalone came either directly from a wild population or from labora-
tory cultivate (F,) stocks. These stocks were maintained and conditioned at the
Department's Marine Culture Laboratory (Ebert, Haseltine, and Kelly 1974)
where all research was performed. Parent stock was conditioned in ambient
temperature (approximately 11-15 C), 15 /xm filtered, continuous flowing
seawater, with a natural photoperiod. Holding tanks were cleaned and supplied
weekly with an excess of fresh giant kelp, Macrocystis sp.
Testing was conducted in a lucite plastic water table measuring 2.4 m by 0.5
m by 0.3 m deep. Seven styrofoam containers, each measuring 28.0 cm by 21.0
cm by 26.0 cm deep, were positioned on the holding table to accomodate the
culture containers. The latter consisted of 10.2 cm inside diameter PVC pipe
sections, 11.4 cm high and screened at the base with 90 jam NITEX® to retain
ova and larvae. The containers were placed on plastic grate shelves situtated to
' Accepted for publication April 1982.
' Mr. Hamilton's current address is: Monterey Bay Aquarium, 886 Cannery Row, Monterey CA 93940
116
CALIFORNIA FISH AND CAME
give each culture container a water volume of 0.5 litre (Figure 1). Filtered
seawater (3 /xnn) was supplied continuously to the seven cultures at a rate of
about 200 ml/min. Five test temperatures were used: 9 C, 12 C, 15 C, 18 C and
21 C
I^^IPIPPPP
FIGURE 1. Experimental apparatus for holding spawned gametes at test temperatures.
Mature parent stock was selected based on gonadal bulk and color. One
male-female pair was used for each test run. Each member of a pair was held
separately in a 15-1 plastic container.
Spawning was induced by using heavily ultraviolet irradiated seawater (Kiku-
chi and Uki 1974a). We used a REFCO^ water purifier, Model RL-10 (REFCO
Purification Systems Inc, San Leandro, Calif.) and 3 /xm filtered seawater. Water
RED ABALONE OVA FERTILITY 1 1 7
flow from the purifier to each of the parent abalones was maintained at about
150 ml/min. Only synchronous spawners or those that spawned within 30 min
of one another were used.
At spawning, about 1,000 ova were pipetted into each of the seven culture
containers at the predetermined test temperature, ± 0.5 C. Sperm was collected
at spawning, concentrated in a 1 litre beaker (400,000/ml), unaerated, and
immersed in a water bath at the test temperature. A 50-ml sperm suspension was
added to one culture with ova at spawning and served as a control. Thereafter,
50 ml of sperm suspension was added hourly to successive ova cultures.
Tests to compare sperm and ova viability were conducted similarly; however,
they were conducted only at 15 C. Also, one male-female pair was spawned
synchronously, followed 3 h and 6 h later by separate male-only spawnings. Ova
were distributed in three containers. Sperm from each male was mixed with one
of the ova samples at the time of spawning. This gave fresh sperm with 0 h, 3
h and 6 h old ova.
Ova fertilization success was determined microscopically using lOOX magnifi-
cation. Four replicate samples of 30 ova each were used for each determination.
Successful fertilization was defined as normal cell cleavage at least to the morula
stage. Fertilization was deemed unsuccessful if cleavage did not occur or if
cleavage planes were aberrant. Fertilization success means and ranges were
calculated.
RESULTS
Thirty-six test runs were conducted from November 1979 through September
1980. Of these, 16 were usable and the remainder rejected. Rejection causes
included (i) asynchronous spawning, (ii) oneor both sexes failed to spawn, (iii)
failure to observe spawning onset, and (iv) insufficient observations following
spawning.
Acceptable test runs included six at 15 C, three at 9 C and 21 C, and two at
1 2 C and 1 8 C. Four of the 1 5 C test runs compared ova and sperm viability loss.
Spawning induction time for male abalones exposed to the ultraviolet-irradiat-
ed seawater took from 2 h 25 min to 4 h, and averaged 3 h 1 min. Concomitant
temperature rise averaged 4.1 C and ranged from 1.0-6.7 C. Spawning induction
for female abalones took from 2 h 45 min to 4 h 30 min and averaged 3 h 8 min.
Concomitant temperature rise averaged 4.3 C and ranged from 1 .3-6.2 C (Table
1).
At both temperature extremes (9 C and 21 C) replicate test runs disclosed
rather wide variations. For instance at 9 C and 0 h post spawning, fertilization
success ranged from 13% to 97% and averaged 54%; at 21 C and 0 h post
spawning, fertilization success ranged from 20% to 85% and averaged 65%.
Gamete viability duration was markedly affected by the 21 C temperature and
no fertilizations were observed after 1 h. At 9 C fertilization success sharply
declined after 1 h post spawning, however some fertilization did occur after 5
h.
The intermediate test temperatures (12 C, 15 C, and 18 C) yielded more
uniform results between replicate tests, and significantly better fertilization suc-
cess at longer time delays in gamete mixing, than did the test temperature
extremes. However, variations were apparent at extended gamete mixing delay
periods. For example, duplicate test runs at 1 5 C after a 4 h gamete mixing delay
yielded 39% and 92% fertilization success.
118 CALIFORNIA FISH AND CAME
Tests to compare sperm and ova viability loss revealed that sperm lost its
viability well in advance of ova. For example, 6 h old ova inoculated with a 6
h old sperm suspension resulted in 3% fertilization success. But, 6 h old ova
inoculated with a freshly spawned sperm suspension resulted in 72% fertilization
success (Figure 2).
TABLE 1. Temperature Rise And Time To Spawning For Sixteen Test Runs Using The
Heavily Ultraviolet Irradiated Seawater Spawning Induction Technique.
Temperature, C
Test run Initial At spawning Time to spawning, hrmin
Temp. (C) male and female male female male female
9 12.0 19.0 19.0 2:25 2:45
9 12.0 18.0 18.0 3:00 3:00
9 14.2 19.0 19.0 3:00 3:00
12 11.1 17.0 17.0 2:51 3:20
12 14.0 18.3 18.0 3K)0 3:00
15 14.0 18.5 18.5 2:30 3:00
15 14.0 18.5 18.8 2:45 2:45
15' 14.0 19.1 19.1 3:30 3:30
15' 16.0 19.0 — 2:30 —
15' 16.0 19.0 — 2:30 —
15' 16.0 19.0 _ _ _
18 12.8 19.5 19.0 4:00 4:30
18 12.5 18.0 18.4 3:00 3:00
21 14.5 17.6 18.0 3:36 3:53
21 17.0 18.0 18.3 3:30 3:30
21 16.0 18.0 18.0 3:10 3:15
' Test runs that compared ova and sperm viability loss.
DISCUSSION
Approximately one-half of the test runs were unusable; however, this high
rejection rate was generally not attributable to the spawning induction method.
In effect, six test runs were rejected because of human factors. For example,
insufficient observations after spawning in the sampling time interval resulted
from a change in our sampling plan following initial test runs. Also, later in the
study period ripe stock became scarce and we had to select from marginally ripe
abalones. This resulted in one or both sexes failing to spawn, insufficient spawn
or clumpy ova, and accounted for nearly 50% of the rejections.
Although wide variation in fertilization success occurred among replicate
samples at test temperature extremes, and at extended gamete mixing delay
periods, an inverse relationship was apparent between the fertilization rate and
the time of gamete mixing post-spawning. This concurs with the observations of
Kikuchi and Uki (1974/?). However, these investigators used just one pair of
abalones, H. discus hannai. Possibly some of the variations in fertilization suc-
cess between our replicate tests were related to genetic differences among the
parent stocks. Also, we did not acclimate parent stocks to a uniform temperature
prior to spawning induction and the ambient seawater temperature varied nearly
5 C during the study period. This could have imposed additional physiological
stress on the gametes depending upon the magnitude of the differential between
ambient seawater and the test temperature.
The tests to compare ova and sperm viability loss revealed that sperm viability
RED ABALONE OVA FERTILITY
119
2lc
100 1
50-^
I
— T"
2
-r-
3
=?=
-r-
6
— r-
7
9c
—I
8
4 5
TIME. HR.
FIGURE 2. Abalone fertilization success (mean %) as a function of temperature and time post-
spawning. The dashed line (15 C graph) indicates the fertilization success obtained
when newly spawned sperm was added to O h, 3 h and 6 h old ova.
120 CALIFORNIA FISH AND CAME
diminished quicker than ova viability. Possibly sperm viability duration can be
extended by maintaining them at a reduced density, at a lower temperature, with
aeration or some combination of these.
Fifteen C apparently is an optimal temperature for fertilization success at
spawning and for gamete mixing delays. We have also found this temperature
is optimum for rearing larval and juvenile stage red abalone.
ACKNOWLEDGMENTS
This research was supported in part by the Bartlett Commercial Fisheries
Research and Development Act (PL 88-309) and California Sea Grant College
Program under grant #R/NP-1-9L to Humboldt State University from the office
of Sea Grant, National Oceanic and Atmospheric Administration, U.S. Depart-
ment of Commerce.
Appreciation is gratefully extended to J. D. DeMartini, Humboldt State Univer-
sity, who helped initiate the study and to our colleagues at the Marine Culture
Laboratory for helping in many various ways.
Appreciation is also extended to R. N. Lea who reviewed the manuscript and
provided many helpful suggestions.
LITERATURE CITED
Ebert, E. E., A. W. Haseltine and R. O. Kelly. 1974. Sea water system design and operations of the Marine Culture
Laboratory, Granite Canyon. Calif. Fish Came, 60 (1):4-14.
Inoue, M. 1969. Mass production and transplantation of abalone. Bull. Kanagawa Fish. Exp. Sta. 131:295-307.
Kikuchi, S. and N. Uki. 1974d. Technical study on artificial spawning of abalone, genus Haliotis II. Effect of irradiated
sea water with ultraviolet rays on inducing spawning. Bull. Tohoku Reg. Fish Res. Lab. 33:79-86.
. 19746. Technical study on artificial spawning of abalone, genus Haliotis. IV. Duration of fertility related
to temperature. Bull. Tohoku Reg. Fish. Res. Lab. 34:73-75.
Morse, D.E., H. Duncan, N. Hooker, and A. Morse. 1977. FHydrogen peroxide induces spawning in molluscs with
activation of prostaglandin endoperoxide synthetase. Science, 196:298-300.
NOTES 121
Calif. Fish and Game b<i {.2): 121-128 1983
NOTES
FIRST CALIFORNIAN RECORD OF THE AMARILLO SNAPPER,
LUTJANUS ARGENTIVENTRIS
On 21 April, 1977, an amarillo snapper, Lutjanus argentiventris (Peters), was
caught by a sportfisherman, George Uman, just inside Oceanside Harbor, San
Diego County, California, in approximately 1.8 m of water. When received by
California Department of Fish and Game personnel, the fish had been eviscerat-
ed but was in otherwise excellent condition. The rose-colored front and yellow-
ish posterior portion of the body were still quite distinct and the joined, blue
spots just beneath the eye formed a brilliant blue stripe. The fish was 410 mm
long and weighed 950 g. Examination of its otoliths revealed six good hyaline
(winter) zones and the beginning of an opaque margin (summer growth).
Based upon this specimen, L. argentiventris appeared in a checklist of Califor-
nia fishes by Hubbs, Follett, and Dempster (1979) and a list of fishes from the
United States and Canada by Robins et al. (1980); neither publication gave
details of its capture.
One of the most recent publications on reef fishes of the tropical eastern
Pacific (Gulf of California) reported that L argentiventris is "the commonest
snapper in the Gulf, ranging from Puerto Penasco to Peru and extending north
outside the Gulf to Bahia Magdalena" (Thomson, Findley, and Kerstitch 1979).
Fitch's (1952) records from Santa Maria Lagoon, located slightly upcoast from
the entrance to Magdalena Bay, do not constitute more northerly captures for
the species. The Oceanside fish, however, does represent a northward extension
of the range on the outer coast by approximately 1040 km.
Only one other member of family Lutjanidae, Lutjanus Colorado, has been
captured off California (Lehtonen 1979). Therefore it was deemed desirable to
offer a few counts and measurements from Mr. Uman's fish (deposited in the
fish collection of the Natural History Museum of Los Angeles County — LACM
36943-1 ) to aid in distinguishing the two species. The following measurements
were recorded: standard length 325 mm; head length 119 mm; orbit width 23
mm; snout to pectoral fin insertion 1 20 mm; snout to pelvic fin insertion 1 38 mm;
snout to dorsal fin insertion 135 mm; snout to anal fin insertion 240 mm; dorsal
insertion to pelvic insertion 115 mm; length of pectoral fin 100 mm. Counts were:
dorsal X, 14; anal III, 8; pored scales in the lateral line, 39. The vomerine patch
of teeth was anchor-shaped with a long posterior extension.
I wish to thank j. Fitch for his guidance, research assistance and editorial help,
and H. Frey for suggestions and editorial assistance. C. Avants typed the manu-
script from my rather rough draft. I especially wish to thank G. Uman for calling
his catch to my attention and for his willingness to part with it for its scientific
value.
Literature Cited
Fitch, J. E. 1952. Distributional notes on some Pacific Coast marine fishes. Calif. Fish Game, 38(4):557-564.
Hubbs, C. L., W. I. Follett, and L. ). Dempster. 1979. List of the fishes of California. Calif. Acad. Sci., Occas. Pap.,
133:1-51.
Lehtonen, P. B. 1979. Colorado snapper, Lutjanus Colorado, taken near Morro Bay adds new family (Lutjanidae)
to California's marine fish fauna. Calif. Fish Came, 65(2)::2C 122.
122 CALIFORNIA FISH AND GAME
Robins, C. R. (Chairman), R. M. Bailey, C. E. Bond, |. R. Brooker, E. A. Lachner, R. N. Lea, and W.B. Scott. 1980.
A list oi the common and scientific names of fishes from the United States and Canada (fourth edition). Am.
Fish, See., Spec. Publ. 12, 174 p.
Thomson, D. A., L. T. Findley, and A. N. Kerstitch. 1979. Reef fishes of the Sea of Cortez. John Wiley & Sons, New
York, XVII + 302 p.
— James E. Phelan, California Department of Fish and Came, Marine Resources
Region. Accepted for publication June 1982. (After a long illness Jim passed
away on 24 Nov. 1982.)
EVIDENCE OF BIRTH OF A SEA OTTER ON LAND IN CENTRAL
CALIFORNIA
There has been considerable speculation and some circumstantial evidence
suggesting that sea otters, Enhydra lutris, in the wild, may give birth on land or
in the water. Scammon (1874) states that otter pups ". . . are brought forth
upon the kelp . . .". Fisher (1940), referring to the California population, states
that parturition takes place in kelp beds. Barabash-Nikiforov (1947), at Mednyi
Island, U.S.S.R., observed two sea otters on shore with newborn pups and
afterbirth nearby and, therefore concluded that birth takes place on land. Ken-
yon (1969), in Alaska, determined the orientation of 43 near-term fetuses and
found about an equal number of them cephalically or caudally oriented. He
suggests that caudal presentation would be adaptive for aquatic birth, and con-
cluded that parturition in sea otters normally takes place on land. Sandegren,
Chu, and Vandevere ( 1 973 ) , in California, observed a sea otter in the water with
a newborn pup, a bloody ano-genital area and an umbilical cord protruding from
the vagina. They subsequently observed the passage of blood and afterbirth into
the water and concluded, probably correctly, that the pup had been born in the
water. Differences observed in northern versus southern populations were at-
tributed to differences in haulout behavior; northern populations haulout fre-
quently and "California otters are rarely seen ashore" (Sandegren et al. 1973).
The following observations were made in my studies of haulout patterns of
sea otters. I used a 50 x 80 Questar telescope at a distance of approximately 1 50
m. Observations were continuous until light conditions precluded seeing the
otters. Times are Pacific Standard. Conditions for viewing were excellent with
high overcast and calm winds and seas.
On 25 May 1981 at 0831 h an otter with a very small pup was sighted
hauled-out on an intertidal reef located approximately 1 km south of Breaker
Point, San Luis Obispo Co., California. The female's head, shoulders, and sides
were dry, indicating that she had been out of the water for more than a few
minutes. She was vigorously grooming a very small pup that was completely wet,
showed no signs of life and had small patches of membranous material and
blood adhering to its pelage. About 5 cm of the umbilical cord was still attached
to the pup's abdomen and 10 to 20 cm of the cord could be seen protruding
from the vagina of the female. The female's chest was wet, where the pup lay,
as were the flippers and ano-genital area. Based on these observations I estimat-
ed that the pup had been born within a few minutes of being sighted.
After approximately 2 minutes of grooming by the female the pup began to
show signs of life by weakly moving its flippers and head. At 0846 h a membra-
nous bag (about 10 cm in diameter) filled with fluid protruded from the vagina.
NOTES 123
At this point the female, lying supinely, stopped grooming the pup, rolled for-
ward and bit the sack which ruptured and released the fluid. She immediately
resumed grooming the pup and continued uninterrupted for 98 min In the total
observation period (432 min) the female groomed the pup 70% of the time
rested for 26% and self-groomed for only 4% of the period. After the continuous
98 mm pup-grooming session, grooming bouts were shorter, ranging from one
to 45 mm. Self-grooming bouts were short (3-8 min) and infrequent Rest
periods were short (21-31 min), but were more frequent.
At 0944 h 73 min after observations began, the placenta and associated tissues
were passed in less than 3 sec. The female paid no attention to the afterbirth
which was quickly dragged away and consumed by an attending western gull
Lams ocadentalis. In the remainder of the observation period, no further materi-
al passed from the female and the vulva appeared clean
By 0930 h the pup was dry and fluffy and could move all four legs and weakly
shake Its head. Several times the pup was in a position where nursing could have
occurred; it nuzzled the female's fur, but I saw no suckling. When the female
was self-grooming, and occasionally during rest periods, the pup was placed on
the algae covered rocks, but 83% of its time was spent on the female's chest
and abdomen.
These observations reveal some interesting aspects of the behavior of parturi-
ent sea otters in California. The mother spends much of the time grooming the
neonate. This probably has several functions, i.e. cleaning, stimulating circulation
and breathing of the newborn, and possibly establishing and reinforcing the
maternal bond. Birth sometimes occurs on land. In this instance there were no
nearby large expanses of giant kelp, Macrocystis pyrifera. The dominant kelp is
bull kelp, Nereocystis lutkeana, which in this area does not form a dense surface
canopy until July. In such areas pupping on land may occur, and in areas where
beds of kelp persist throughout the year, aquatic births (as reported by Sandegr-
en er j/. 1973) may be common. Therefore, environmental differences and
individual variation are probably more important in determining the place of
parturition in sea otters than are behavioral differences between populations.
LITERATURE CITED
Barabash-Nikiforov I. I. 1947 Kalan (The sea otter, in Russian, translated by Dr. A. Birron and Z. S Cole 1962)
Israel Program for Scientific Translations, Jerusalem. 227 pp.
Fisher, E. M. 1940, Early life of a sea otter pup. J. Mammal., 21 (2):132-137.
"^^^ Washin^onl^C^SsYpp °"^' '" """ ^'''''" '''''^'' °'''"- "^^ ^"'^'- ^'""'- ^- ^'^^ ^°^- ''^'"^'"^ Off.
Sandegren,^F^E^W. Chu, and J. E. Vandevere. 1973. Maternal behavior in the California sea otter. J. Mammal.,
^"Tr;5 ^„o®^'*- ^^^ ""^''"^ mammals of the northwestern coast of North America. John H. Carmany, San
rrancisco. ji9 pp. "
T^J^ZI^JrJ- i^'^^'"'''' ^-^- ^^^ ^^d Wildlife Service, P.O. Box 67, San Simeon,
LA. 93452. Accepted for publication October 1981.
124 CALIFORNIA FISH AND CAME
AGE AND GROWTH AND LENGTH-WEIGHT RELATIONSHIP FOR
FLATHEAD CATFISH, PYLODICTIS OUVARIS, FROM COACHELLA
CANAL, SOUTHEASTERN CALIFORNIA
Flathead catfish were introduced in 1962 into Martinez Lake, Arizona, on the
lower Colorado River (Anonymous 1980). They quickly spread into canals of
the Imperial Valley, California (Bottroff, St. Amant, and Parker 1969), and up-
stream in the river to Parker Dam (Minckley 1973). To date, nothing has been
published on age and growth or length-weight relationship of the species from
this area. Flathead catfish are native to the Rio Grande-Mississippi River complex
of central North America (Clodek 1980).
METHODS AND MATERIALS
Three sections of the Coachella Canal (T11S, R15E, and T15, R19E, San
Bernardino Meridian) were blocked by 2.5-cm-mesh nets prior to a water out-
age (Minckley 1981 ). When water levels receded, sections were further isolated
by earthen dikes. A concrete box siphon that comprised one study section was
breached and water was pumped from the structure to allow access and sam-
pling. Emulsifiable rotenone was applied to all sections at greater than 2.5 mg/
liter active ingredients and affected fishes were collected by nets and seines.
Fish were measured to the nearest centimetre from the tip of the lower jaw
to the tip of the caudel fin and weighed in pounds (later converted to metric
system) in the field. Fish less than 15 cm long were preserved in 10% formalin
for analysis in the laboratory. No adjustments were made for possible changes
in length or weight following preservation.
Pectoral spines were disarticulated and excised, dried after removal of soft
tissues in dilute potassium hydroxide, and sectioned with a jeweler's saw follow-
ing procedures of Turner (1977). Thin sections were polished on emery paper
and examined under alcohol and reflected light with a binocular microscope.
Spine diameters at the point of sectioning were measured to the nearest 0.1 mm
by Vernier calipers; anterior radius and anterior radius to each annulus were
recorded to the nearest 0.01 mm by ocular micrometer.
Back calculation of lengths at consecutive annuli was by the equation:
L' = C -f S7S(L - C),
where L' is fish length when annulus "x" was formed, L is the length at capture,
S' is the anterior spine radius at the n* annulus, S is total anterior spine radius,
and C is the intercept value from least squares linear regression of fish length and
spine diameter at the point of sectioning. Size-frequency distribution clearly
segregated fish of Age Group 0, and this was verified by examination of spines
from 10 young-of-the-year fish of varying lengths.
RESULTS AND DISCUSSION
Flathead catfish comprised about 1.0% (94 specimens) of about 9,000 fishes
taken in sampling from the Coachella Canal (Minckley 1981 ). Other abundant
fishes included channel catfish, Ictalurus punctatus; bluegill, Lepomis macro-
cA/ri/s; largemouth bass, Micropterus sa/moides; ihreadi'm shad, Dorosoma pete-
nense; red shiner, Notropis lutrensis; and carp, Cyprinus carpio. All are included,
when of appropriate size, in the diet of flathead catfish in the lower Colorado
River (Minckley 1982). Fishes were abundant, with 0.55 to 1.08 individuals
/m ^ recovered. Biomass also was high, with 49.4 and 102.0 g/m ^ in the two
samples from the open canal, and 593.9 g/m ^ in the siphon (25% of the latter
were flathead catfish; Minckley 1981).
NOTES
125
Spine diameter at the point of sectioning correlated highly (r — 0.98) with
length of flathead catfish, with the regression described by the formula Y
= 1 3.6 + 1 37X. Calculated lengths at each annulus (Table 1 ) compared favora-
bly with age groups indicated by length-frequency distribution (Figure 1 ), and
with lengths at capture of the next youngest year classes. Since no indications
of annuli were near spine edges of any age group, the fish would presumably
have grown prior to annulus formation in January (the coolest month in the
region; Jaeger 1957) to approximate calculated lengths at annuli. Length-weight
relationship is described by the formula Log W = —5.2500 + 3.1441 Log L.
TOTAL LENGTH, CM
FIGURE 1 . Size frequency distribution of 75 flathead catfish from the Coachella Canal, California.
Numbered brackets indicate ranges in total length at capture for fish aged by examina-
tion of pectoral spines. Some lack of correspondence with Table 1 results from addi-
tional fish being included here.
Growth rates of flathead catfish from the Coachella Canal were comparable
to, or exceeded, those in reservoirs and rivers within their native range (Table
2 ) . Their length-weight relationship is, expectedly, more like riverine populations
than those in reservoirs.
ACKNOWLEDGMENTS
The U.S. Bureau of Reclamation, Boulder City, Nevada, supported this study
with funding (Purchase Order No. 1-01-30-04780), equipment, and manpower.
W. Rinne of the Bureau deserves special thanks. The California Department of
Fish and Game also provided assistance.
126
CALIFORNIA FISH AND CAME
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128 CALIFORNIA FISH AND CAME
LITERATURE CITED
Anon. 1980. Special report on distribution and abundance of fishes of the lower Colorado River. Final Rept. U.S.
Bureau Reclamation, Boulder City, Nev., Contr. No. 9-O7-O3-X0O66, U. S. Fish Wildl. Serv., Phoenix, Ariz, ii
+ 157 p.
Bottroff, L., ]. A. St. Amant, and W. Parker. 1969. Addition of Pylodictis olivarisXo the California fauna. Calif Fish
Game, 55(1):90.
Cross, F. B., and C. E. Hastings. 1956. Ages and sizes of thirty-nine flathead catfish. Kans. Acad. Sci., Trans.
59(1):85-86.
Clodeck, G. S. 1980. Pylodictis olivaris (Rafinesque), flathead catfish, p. 472, in D. S. Lee, etal., eds. Atlas of North
American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, N. C. x -(- 854 p.
Jaeger, E. C. 1957. The North American Deserts. Stanford Univ. Press, Stanford, Calif, x + 308 p.
Jenkins, R. M. 1954. Growth of the flathead catfish, Pylodictis olivaris, in Grand Lake, Oklahoma. Okla. Acad. Sci.,
Proc., 33(1): 11-20.
McCoy, H. A. 1953. The rate of growth of flathead catfish in twenty-one Oklahoma lakes. Okla. Acad. Sci., Proc.,
34(1): 47-52.
Minckley, W. L. 1973. Fishes of Arizona. Ariz. Came Fish Dept., Phoenix, Ariz, xvi -(- 293 p.
. 1981. Fishery inventory of the Coachella Canal, southeastern California. Final Rept. U. S. Bureau Reclama-
tion, Boulder City, Nev., Purch. Ord. No. 1-01-30-04780, Ariz. State Univ., Tempe, Ariz, ii + 25 p.
-. 1982. Trophic interrelationships among introduced fishes of the lower Colorado River, southwestern
United States. Calif. Fish Game, 68(2): 78-89.
Minckley, W. L. and J. E. Deacon. 1959. Biology of the flathead catfish in Kansas. Amer. Fish. Soc, Trans., 88(4):
344-355.
Turner, P. R. 1977. Age determination and growth of flathead catfish. Unpubl. Dissertation. Okla. State Univ.,
Stillwater, Okla. 146 p.
— Mark S. Pisa no, Mary J. Inansci, and W. L. Minckley, Department of Zoology,
Arizona State University, Tempe, Arizona 85287. Accepted for publication Janu-
ary 1982.
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