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CAUFDRNIAl

FISH-GAME

"CONSERVATION OF WILDLIFE THROUGH EDUCATION"

1 VOLUME 63

JANUARY 1977

NUMBER lj

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California Fish and Gany is a journal devoted to the conservation of wild-
life. If its contents are reproduced elsewhere, the authors and the California
Department of Rsh and Gome would appreciate being acknowledged.

Subscriptions may be obtained at the rate of $5 per year by placing an
order with the California Department of Rsh and Game, 1416 Ninth Street,
Sacramento, California 95814. Money orders and checks should be mode out
to California Department of Fish and Game. Inquiries regarding paid sub-
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Complimentary subscriptions are granted, on a limited basis, to libraries,
scientific and educational institutions, conservation agencies, and on exchange.
Complimentary subscriptions must be renewed annually by returning the post-
card enclosed with each October issue.

Please direct correspondence toi

Robson A. Collins, Editor
California Fish and Gam9
350 Golden Shore
Long Beach, California 90802

1
J

VOLUME 63

JANUARY 1977

NUMBER 1

Published Quarterly by

STATE OF CALIFORNIA

THE RESOURCES AGENCY

DEPARTMENT OF FISH AND GAME

STATE OF CALIFORNIA

EDMUND G. BROWN JR., Governor

THE RESOURCES AGENCY
CLAIRE T. DEDRICK, Secretary for Resources

FISH AND GAME COMMISSION ^
BERGER C. BENSON, President, San Mateo

JOSEPH RUSS III, Member SHERMAN CHICKERING, Vice President ^

''*^"''°l« Son Francisco *
TIMOTHY M. DOHENY, Member ELIZABETH L. VENRICK, Member

Los Angeles Cordiff-by-the-Seo ^

DEPARTMENT OF FISH AND GAME

E. C. FULLERTON, Director

1416 9th Street

Sacramento 95814

CALIFORNIA FISH AND GAME

Editorial Staff

ROBSON A. COLLINS, Editor-in-Chief Long Beach <,

KENNETH A. HASHAGEN, Editor for Inland Fisheries Sacramento

CAROL M. FERREL, Editor for Wildlife Sacramento

ROBERT N. TASTO, Editor for Marine Resources Menio Park

STEVEN N. TAYLOR, Editor for Salmon and Steelheod SocramentOi.

HAROLD K. CHADWICK, Editor for Striped Boss, Sturgeon, and Shad Stockton

►-

♦

CONTENTS

Page

The Status of Brown Pelicans at Anacapa Island in 1975

Daniel W. Anderson, Ronald M. Jurek and James O. Keith 4

Supplemental data on the food habits of the
Western Cray Squirrel Walter E. Stienecker 11

■ Effects of Salinity on Larval Growth in the California Killifish, Fundulus

parvipinnis Cirard Teegavarapu R. Rao 22

Detection of Delayed Annulus Formation Among Bluegill Tepomis
macrochirus, Populations at Lake Nacimiento, California

Delores Brown, Edward E. Miller and C. E. von Geldern Jr. 29

'Stomach Contents of Northern California Dungeness Crabs, Cancer

r magister. Daniel W. Gotshall 43

Reactions of Fish Red Blood Cells with Mucus and Sera

* from Other Fish(es) Albert C. Smith 52

Notes

Extension of Red Fox Distribution in California Randall L. Gray 58

Acorn Selection by Band-Tailed Pigeons

♦ Michael E. Fry and Charles E. Vaughn 59

Alabama Spotted Bass grow at Record Rate in Lake Perris, California

Delores Brown, Kenneth Aasen and C. E. von Geldern, Jr. 60

Birth of a California Sea Lion on Southeast Farallon Island

Raymond J. Prerotti, David G. Ainley and T. James Lewis 64

Observations on the Breeding Behavior of the Harbor Seal in
'' Humboldt Bay, California Peter M. Knudtson 66

Notes on Some Fishes Collected off the Outer Coast of
Baja California Glenn F. Black 71

Calif. Fish and Came 63 ( 1 ) : 4- 1 0. 1 977.

THE STATUS OF BROWN PELICANS AT
ANACAPA ISLAND IN 1975 ^

DANIEL W. ANDERSON ^

U.S. Fish and Wildlife Service

Davis, California

RONALD M. JUREK

Wildlife Management Branch

California Department of Fish and Game

Sacramento, California

and

JAMES O. KEITH

U.S. Fish and Wildlife Service

Federal Center, Denver, Colorado

nif hl« °' "7 °" productivity, chemical residues, and eggshell thickness of Califor- ^
n.a brown pel.cans at Anacapa Island and nearby Santa Cruz island suggest that the
Sir? "* '!.'l'r'"?«^'°'" D?T-'elated reproductive failures. The improved pro! ^
of DDE'a'nn«h °n 'fV""*' • ""^ **''°"«'' ""'• "°^*^^'' P'^H^uctivity, resid'^^ '
o ?q74 ^.aa!^ l* wu""' '" l'^^ ^^'^ "«» significantly different from those i
of 1974 suggesting that the rate of improvement has begun to level off Pelican
productivity is still too low for population stability
Chemicals other than DDE are discussed. PCBs were also found at levels of possi-

ized '" '"*'"°"* ''"" (1%9-72), but recent levels seem to have stabS-

Brown pelican colonies will require continued monitoring for some years to come
We recommend that the California brown pelican be retained on the CalifomU^i ,
2 Z nTll' ^'Tk' "^ ' ^ P'^Hl^ctivity exceeds 1.0 young per nest anempTand
2) the numbers of breedmg adults in California waters begin to increase. >

INTRODUCTION
The status of brown pelicans {Pelecanus occidentalis californicus) in the**
coastal waters of California and just south into Mexico at Islas Los Coronados
through 1974 was reviewed by Anderson et al. (1975) and Anderson and.
Anderson (1976). In 1971, there was enough concern about the brown pelican
population decline in the Channel Islands area to have the subspecies placed on^
California s list of "endangered wildlife" (Leach 1972, 1974). Although brown
foinf 1 ^''*°^'"' V ^f'^f "ested on other islands in California waters (Gress^
1970), Anacapa sland (lat 34»01'N, long 119'26'W) and nearby Scorpion Rock^
off Santa Cruz Island (lat 34»03'N, long 119°33'W) have been the only nesting
Sites used m California waters since our studies were initiated. The California'
nesting population of brown pelicans has been monitored since 1969 by a team
nTpw^^^f^f M^"^ of Fish and Game (DFG), U.S. Fish and Wildlife Service
(USFWS), U^S. National Park Service (USNPS), and University of California •

I I ! '^^""Jl ^'^ °" ^^^ ^^^^"^ °^ P^''^^" colonies on Anacapa and Santa Cruz.
Islands in 1975. Reasons for the decline of Califomia's brown pelicans will not

' Present address: Division of Wildlife and Fisheries Biology, University of California, Davis 95616.

STATUS OF BROWN PELICANS 5

be reviewed here (see Anderson and Anderson 1976). A significant recovery in
pelican productivity (young fledged per nest attempt) began around 1972 (An-
derson et al. 1975). Productivity in 1974 was significantly better than that ob-
served from 1969 to 1973.

', Owing to the extreme severity of the brown pelican problems formerly caused
by DDT pollution, only DDT and metabolites were reported by Anderson et al.
(1975). In this report, we will also discuss other chemical pollutants found in
brown pelican eggs off Southern California.

METHODS

Colony surveys were conducted throughout the breeding season from a boat

anchored below the colonies by the Department of Fish and Game and U.S.

J National Park Service on 30 March, 10 April, 22 April, 30 April, mid-June, 8

J August, and 8 September. On most occasions, one or more of us were present

i, on these surveys. No entries were made into the nesting area until all young were

of bandable size. After that, when human presence was no longer hazardous (on

8 August and 8 September), the nesting areas were entered and more accurate

productivity data were obtained. Eggshells and addled eggs were collected. We

found no carcasses in 1975. Young were banded and color-marked.

Our methods of chemical analysis for organochlorine residues are cited by
Anderson et al. (1975). Residue analyses reported here were conducted by the
USFWS, Denver Wildlife Research Center, Denver, Colorado. Residues of or-
ganochlorine pollutants are given as ppm lipid-basis. To convert these to a rough
estimate of ppm fresh-weight basis, multiply our values by 0.05.
I Unfortunately, in 1975 we recovered only four intact brown pelican eggs that
'-were suitable for chemical analysis; three of these were dried and putrified.
Stickel et al. (1965) reported exaggeration of egg residues by as much as eight
times in dessicated eggs. Putrefaction apparently does not decompose the or-
ganochlorines (Mulhern and Reichel 1970), although it is essential to adjust
residues for losses of moisture. Incubation and possibly putrefaction apparently
resulted in the loss of some egg lipids in three eggs ( see Romanoff 1 932 ) to about
0.6 of their normal value. Five to 6% lipid content is normal for fresh brown
pelican eggs (D. W. Anderson unpublished). We therefore corrected residues
' in our 1975 sample for lipid and water loss (Stickel et al. 1973) and then
converted them to a lipid-basis, assuming 5% lipids, so that they would be
comparable with previous years' data. Residues of heavy metals were analyzed
by atomic absorption spectrophotometry according to the methods described
- by i. Okuno, Denver Wildlife Research Center.

RESULTS
^ Productivity of Brown Pelicans

At least three periods of nesting activity were apparent during the nesting
• season of 1975 on Anacapa and nearby Santa Cruz. This asynchronous nesting
^ pattern made our surveys more difficult than in previous years, but we are
' confident that out estimates are accurate.

Production on the separate islands was as follows in 1975: Anacapa — 212

nests, 182 young produced; Santa Cruz — 80 nests, 74 young produced. The two

' colonies combined produced 0.88 young per nest attempt. This compares with

^ 0.73 in 1974, 0.14 in 1973, 0.22 in 1972, and 0.007 in the period 1969-71 for the

6 CALIFORNIA FISH AND CAME

same colonies (Anderson and Anderson 1976).

Our productivity estimates for 1975 suggest a slight improvement over 1974,
but this was not statistically significant as suggested by the overlap of the 95%
confidence intervals (CIs) of the two estimates (Steel and Torrie 1960): 1975 —
CI = 0.79-1.03, 1974— CI = 0.51-1.05.

Residues in Brown Pelican Eggs
Mean DDE residues in 1975 (ppm lipid-basis) were slightly higher than in
1974 (Table 1), but not significantly so (Wilcoxon two-sample test, P > 0.1,
Sokal and Rohlf 1969:391-394). Eggshell thickness did not differ significantly
between 1974 and 1975 in either intact or broken eggs (Table 1 ).

TABLE 1. Pollutant Residues and Eggshell Thicknesses of Brown Pelican Eggs from Anacapa
island in 1975 Compared with Previous Years' Data from the Same General Area.

Year

Measurements 1969* JWT 7974^ TWT

Chemicals (geometric X, ppm) n = 28 n = 4 n = 39 n = 4

MP'-DDT + M/7'-DDD (lipid-wt.) 54 7 ND ND

M/t'-DDE (lipid-wt.) 853 175 97 113

PCB (lipid-wt.)t 200 43t 146 120

Hexachlorobenzene (lipid-wt.) — — — 0.09

Mercury (wet-wt.) — 0.30 — 0.10

Lead (wet-wt.) — 0.18 — 0.14

Cadmium (wet-wt.) ^ — <0.0S — <0.05

Shell Thickness (arith. X, mm)

Intact eggs, mean ± 95% CI 0.40 0.51 0.48 0.51

±0.02 ±0.07 ±0.02 ±0.04

Intact eggs, sample size 12 4 59 9

Broken eggs, mean ± 95% CI 0.29 0.34 0.38 0.36

±0.02 ±0.03 ±0.03 ±0.06

Broken eggs, sample size 53 26 27 13

* Data on DDT and metabolites are from Anderson et al. (1975). A dash means that the residue was nH

determined, and ND means the chemical was tested for, but not detected. Chemicals are reported for intact

eggs only.
t 1969 PCB residues are from Risebrough (1972) and were quantified on the basis of Arochlor 1254. The 1973-7;"

PCBs were quantified on the basis of Arochlor 1260. Therefore, these residues are not rigorously comparable.

A correction factor of 2.15 (Risebrough and deLappe 1972) was applied to the data, but no statistical test was

made.
X Without one value of 6 ppm, this mean would be 86 ppm.

Residues of PCBs ( polychlorinated biphenyls ) ( Peakall and Lincer 1 970, Dust-
man et al. 1 971 ) , although not associated with eggshell thinning in birds ( Peakall
and Peakall 1973), may be responsible for parental behavior changes observed
in the Anacapa brown pelicans (i.e., reduced nest attentiveness) (Peakall and,
Peakall 1973, Cress 1970). Mean PCB residues (lipid-weight) were around 200
ppm in 93 intact and crushed eggs at Anacapa in 1969 (Risebrough 1972), but
averaged 146 ppm in 1974 and 120 ppm in 1975 (Table 1). Although these
residues were measured by different laboratories, the data suggest that PCBs
may have declined since 1969, but not as dramatically as did DDT and metabo-
lites over the same time period (Anderson etal. 1975) (Figure 1 ). DDE and PCB
residues in eggs appear to have remained essentially unchanged in the last 2'
years, but the possible discrepancies in analyses of PCBs do not allow statistical
testing of the hypothesis of a decline in PCBs since 1969. Young and Szpila

STATUS OF BROWN PELICANS

..(1975) have reported a recent decrease in PCBs in mussels {Mytilus califomi-
\\cus) of Southern California; as with pelicans, the decrease in PCBs was less than
I that in DDT compounds.

00
I

Q
CL

900

700-

500

300-

100-

YEAR

^ FIGURE 1. Residue changes of DDE and PCB in intact brown pelican eggs from Southern Califor-
nia. The arrow indicates a major drop in environmental input of DDT. According to
published data, major input of DDT ceased in 1970 (Anderson et al. 1975) and by 1971
it had decreased to about 0.5% of previous levels (Jukes 1974, citing the DDT-manu-
facturing company president). There is some disagreement as to the actual levels of
input before 1970 (jukes 1974).

The Other major organochlorine residue found in pelican eggs at Anacapa
.Island wasdieldrin. The mean dieldrin level (lipid-basis) was 1.29 ppm in seven
of the 1973-74 pelican eggs, but less than 1 ppm (the level of analytical sensitiv-
ity) in the other 36. Fourteen additional eggs of normal shell thickness, collected
in 1973 in the Gulf of California (D. W. Anderson USFWS, unpublished data),
"contained a mean of 0.95 ppm dieldrin. No dieldrin was detected above the level
of analytical sensitivity in our small sample of pelican eggs from 1975. Dieldrin
levels were similarly low at Anacapa in 1969, with a mean of 0.98 ppm lipid-basis
for 1 9 eggs in which the chemical was tested ( R. W. Risebrough pers. commun. ) .
This level was judged to be unrelated to eggshell thinning in Anacapa brown
pelicans (Risebrough 1972).

We also conducted a small number of analyses for residues of mercury, lead,
and cadmium (Table 1 ). All of the levels were low, as were those found in
Anacapa eggs in 1971 (Conners et al. 1972) and in 22 eggs collected in the Gulf
of California in 1973 (D. W. Anderson USFWS, unpublished data). Means were:

8 CALIFORNIA FISH AND CAME

0.58 ppm Hg, 0.10 ppm Pb, and <0.05 ppm Cd (all residues of metals expressed
on a ppm fresh-weight basis of egg contents). Sell (1975) has reported that
domestic poultry retain little ingested cadmium (4% after 23 days), and that
virtually none is deposited in either the egg yolk or albumin. Therefore, the low
cadmium levels we report here are difficult to evaluate and probably do not truly
reflect exposure. Lead and mercury, like dieldrin, appear to be unrelated to the
past reproductive-eggshell problems of Anacapa's brown pelicans. Cadmium
levels need to be determined from other tissues, but we do not suspect that levels
in the Anacapa area are unusually high (Martin and Broenkow 1975).

DISCUSSION

Our 1975 data indicate that the improvement in brown pelican productivity
reported in 1974 (Anderson et al. 1975) is continuing, but with the rate of
improvement leveling off. Our data on eggshell thickness and pollutant residues
support this conclusion (Table 1 ). The continued improvement is encouraging,
but it may be that DDE levels have again "stabilized" in the brown pelicans off
Southern California (Figure 1) and that a complete recovery of reproductive
potential is still some years in the future.

DDE is persistent with an unusually long half-time, it accumulates at low
dietary levels, and mobilizes rapidly and at realistically low laboratory doses
(review by Stickel 1975). The eggshell thinning effect of DDE persists, although '
it lessens, at least 1 year, and likely more (W. H. Stickel pers. commun.), after
experimental birds are placed on clean diets (Haegele and Hudson 1974). The
situation off California might be considered as an acute problem becoming a
chronic one.

Apparently, the non-DDT residues examined in brown pelican eggs are either
at low levels or not changing rapidly. Some of these pollutant levels may repre-
sent additional, less acute, and less obvious ecological problems off Southern
California, such as those that might be manifested by low levels of PCBs or
combinations of DDE and PCB (Risebrough and Anderson 1975). These and the
heavy metal residues will be difficult to evaluate ecologically and physiological-
ly.

We estimate that current productivity is still 10-30% below what it should be
to maintain long-term population stability, depending on how the data are
interpreted. A "recruitment standard" has been postulated to estimate the
necessary productivity for brown pelicans by Henny (1972) based on a small
sample size of band recoveries for the eastern subspecies. Based on more recent
field studies on productivity (D. W. Anderson and R. W. Schreiber USFWS,
unpublished data, Schreiber 1975) the figure postulated by Henny (1.2 to 1.5)
seems too high.

For example, the populations of brown pelicans in Florida are relatively sta-
tionary (Williams and Martin 1970, Schreiber and Schreiber 1973, Schreiber
1976). One colony on the west coast of Florida has been monitored for 7 years
by R. W. Schreiber (pers. commun.); this colony has produced an average of
about 1.0 young per nest (range = 0.3 to 1.7) from 1969 to 1975 (Schreiber
1975). This colony, colonies on the west coast of Florida, and colonies through-
out Florida have not shown any trend of decline (Schreiber and Schreiber 1 973 ) .
Only long-term studies will reveal what constitutes the average productivity or
recruitment that will interact with mortality and immigration to produce popula-

STATUS OF BROWN PELICANS 9

tion stability or increase in the brown pelican.

Also, as Anderson et al. (1975) pointed out, different proportions of the total
adult pelican population breed from year to year. Thus it becomes difficult to
estimate if a population is increasing or decreasing on the basis of short-term
colony census data. There is no doubt that the population of brown pelicans
breeding off Southern California is currently much smaller than it was prior to
1949 (Anderson and Anderson 1976), and there is no doubt that productivity
has improved since 1971. Recruitment of new breeders from the 1974-75 pro-
duction probably will not be seen until recently-produced pelicans are 3-5 years
old (Anderson and Anderson 1976). Only time will tell if the breeding popula-
tion increases because of the improvement.

Long-term productivity above about one young per nest attempt, coupled
with a sustained increase in the breeding population of brown pelicans off
California, should be the minimum criteria in judging whether to remove brown
pelicans from the State's list of endangered fauna. In conclusion, we recommend
that the brown pelican be retained on the California list of endangered fauna,
since the State's only viable pelican colonies on Anacapa and Santa Cruz are
still not reproducing sufficiently for population stability (Anderson et al. 1975).

ACKNOWLEDGMENTS

Our studies have been coordinated by H. R. Leach (DFG), and we are grateful
for his continuing support. The USNPS, Channel Islands National Monument,
has provided continual aid in the field. W. H. Ehorn and F. Jacot have cooperated
in our research and continually responded to our management recommenda-
tions for Anacapa Island. The USFWS, Denver Wildlife Research Center has also
provided continuous support for brown pelican research on the West Coast. We
are grateful to H. H. Hoover for continuing assistance. R. E. White and the
laboratory at the Denver Wildlife Research Center conducted our chemical
analyses. R. W. Schreiber and W. H. Stickel made valuable comments on the
manuscript.

In 1976, productivity on Anacapa declined to 0.67 young per nest (n-about
4(X) nests). There was no pelican nesting on Santa Cruz in 1976. Visits into the
Anacapa colony were too late to obtain eggshells and addled eggs, but analysis
of two young found dead on the colony (A.L. Bischoff pers. commun.) indicated
low organochlorine residues. The poor 1976 productivity was at least in part due
to a failure as suggested by: 1 ) badly emaciated dead young in the colony, and
2) low numbers of adults in or near the colony on 25 July (19 compared to
around 1,000 in previous years). Young were produced in 1976, but the nesting
season was asynchronous and many young starved on the colony before fledg-
ing. Surveys will continue in 1977. — D.W.A.

REFERENCES

Anderson, D. W., and I. T. Anderson. 1976. Distribution and status of brown pelicans in the California Current.
American Birds, 30(1): 3-12.

). R. Jehl, Jr., R. W. Risebrough, L. A. Woods, Jr., L. R. DeWeese, and W. C. Edgecomb. 1975. Brown

pelicans: improved reproduction off the Southern California coast. Science, 190(4216): 806-808.

Conners, P. C, V. C. Anderlini, R. W. Risebrough, J. H. Martin, R. W. Schreiber, and D. W. Anderson. 1972.
Heavy metal concentrations in brown pelicans from Florida and California. Cal-Neva Wildl., 1972: 56-64.

10 CALIFORNIA FISH AND CAME

Dustman, E H., L. F. Stickel, L. ) Blus, W. L. Reichel, and S. N. Wiemeyer. 1971 The occurrence and

significance of polychlorinated biphenyls in the environment. N. Amer. Wildl. Nat. Res. Conf., Trans, 36:

118-133.
Cress, F. 1970. Reproductive status of the California brown pelican in 1970, with notes on breeding biology and

natural history. Calif. Dept. Fish and Came, Wildl. Manage. Br. Admin. Rep., 70-6. 21 p., mimeo.
Haegele, M. A. and R. H. Hudson. 1974. Eggshell thinning and residues in mallards one year after DDE

exposure. Arch. Environ. Contam. Toxicol., 2: 356-363.

Henny, C ). 1972. An analysis of the population dynamics of selected avian species: with special reference to
changes during the modern pesticide era. U.S. Fish Wildl. Serv. Wildl. Res. Rep., 1: 41-46.

jukes, T. H. 1974. Insecticides in health, agriculture, and the environment. Naturwissenschaften, 61: 6-16.

Leach, H. R. 1972. Our endangered wildlife. //?.• At the crossroads: a report on California's endangered and rare
fish and wildlife, January 1972. Calif. Dept. Fish and Came. 99p.

1974. Birds and mammals. In: At the crossroads 1974: a report on California's endangered and rare

fish and wildlife, January 1974. Calif. Dept. Fish and Came. 112p.

Martin, J. H., and W. W. Broenkow. 1975. Cadmium in plankton: elevated concentrations off Baja California.
Science, 190 (4217): 884-885.

Mulhern, B. M., and W. L. Reichel. 1970. The effect of putrefaction of eggs upon residue analysis of DDT and
metabolites. Bull. Environ. Contam. Toxicol., 5(3): 222-225.

Peakall, D. B., and J. L. Lincer. 1970. Polychlorinated biphenyls: another long-life widespread chemical in the
environment. BioScience, 20(17): 958-964.

and M. L. Peakall. 1973. Effect of a polychlorinated biphenyl on the reproduction of artificially and

naturally incubated dove eggs. J. Appl. Ecol., 10(4): 863-868.

Risebrough, R. W. 1972. Effects of environmental pollutants upon animals other than man. Berkeley Symp. on
Math. Statist, and Probability, Proc., 4: 443-464.

, and D. W. Anderson. 1975. Some effects of DDE and PCB on mallards and their eggs. J. Wildl.

Manage., 39(3): 508-513.

and B. deLappe. 1972. Accumulation of polychlorinated biphenyls in ecosytems. Environ. Health

Perspectives, 1(1): 39-45.

Romanoff, A. L. 1932. Fat metabolism of the chick embryo under standard conditions of artificial incubation.
Biological Bull., 52(1): 54-62.

Schreiber, R. W. 1975. Reproductive success of the brown pelican [Pelecanus occidentalis) , Tarpon Key,
Pinellas County, Florida 1969-1975. Proc. 93 Stated Meeting A.O.U.

1976. Brown pelican species account. Florida Comm. on Rare and Endangered Plants and Animals.

, and E. A. Schreiber. 1973. Florida's brown pelican population: Christmas Bird Count Analysis.

American Birds, 27(4): 711-715.

Sell, J. L. 1975. Cadmium and the laying hen: apparent absorption, tissue distribution and virtual absence of
transfer into eggs. Poultry Sci., 54(5): 1674-1678.

Sokal, R. R., and F. J. Rohlf. 1969. Biometry: the principles and practice of statistics in biological research. San
Francisco. W. H. Freeman and Co. 776p.

Steel, R. C. D., and J. H. Torrie. 1960. Principles and procedures of statistics: with special reference to the
biological sciences. New York. McGraw-Hill Book Co. 481 p.

Stickel, L. F., F. C. Schmid, W. L. Reichel, and P. L. Ames. 1%5. Ospreys in Connecticut and Maryland. U.S.
Fish and Wildl. Serv. Circ, 226: 4-6.

, S. N. Wiemeyer, and L. J. Blus. 1973. Pesticide residues in eggs of wild birds: adjustment for loss

of moisture and lipid. Bull. Environ. Contam. Toxicol., 9(4): 193-1%.

Stickel, W. H. 1975. Some effects of pollutants in terrestrial ecosystems. In: Ecological Toxicology Research (A.
D. Mclntyre and C F. Mills, eds.). Plenum, New York.

Young, D. R., and I. S. Szpila. 1975. Decreases of DDT and PCB in mussels. /«.• Coastal Water Research Project:
annual report 1975. Southern Calif. Coastal Water Res. Proj., El Segundo, California. 21 1p.

Williams, L. E,, jr., and L. L. Martin. 1970. Nesting populations of brown pelicans in Florida. Southeastern Assoc.
Came Fish Comm., Proc. Ann. Conf., 24: 154-169.

Calif. FishandCame 63 (1): 11-21. 1977.

SUPPLEMENTAL DATA ON THE
FOOD HABITS OF THE WESTERN CRAY SQUIRREL ^

WALTER E. STIENECKER

Wildlife Management Branch
California Department of Fish and Came

Supplemental data from Kern, Mendocino, Sonoma, Napa, Shasta and Tehama
counties substantiates the feeding habits pattern of the western gray squirrel over
much of its California distribution. Hypogeous fungi, oak acorns, pine nuts and
California bay fruits comprise the bulk of the food eaten by gray squirrels. The types
of fungi and principal food items are eaten in a pronounced seasonal pattern.

INTRODUCTION
The purpose of this report is two-fold:

1 ) To add supplementary information to available data on the food habits
of the western gray squirrel {Sciurus griseus) from Tehama, Trinity, El
Dorado, Nevada, Calaveras, Amador and Humboldt counties (Stie-
necker and Browning 1970).

2) To document the similarity of the food habits pattern of gray squirrels
throughout their statewide distribution.

The principal collection areas considered are in Mendocino and Kern coun-
ties. Supplemental collections were made in Sonoma, Napa and Shasta counties
(Figure 1); an additional sample is from Tehama county.

DESCRIPTION OF THE PRINCIPAL AREAS

Mendocino Collection Area

This sample was taken on the University of California Hopland Field Station,
located in the southeast corner of Mendocino County. Cray squirrels were
collected below the chaparral belt at an elevation between 244 to 549 m (800
to 1,800 ft). A woodland-grass association characterizes the greater part of the
collection area. The overstory consists of blue oak (Quercus douglasif), valley
oak (Quercus lobata), and California buckeye [Aesculus californica) . In the
dense woodland type, located in small ravines along the streams and on the
north slopes, the principal trees are live oak [Quercus agri folia) , California bay
(Umbellularia californica), madrone {Arbutus menziesif) and black oak {Quer-
cus kelloggii). Between 1951-1960 the average rainfall was 94 cm (37 inches)
per year at the Hopland Field Station. During the period, the first freezing
temperatures took place between October 6 and November 18. The last frost
occurred between March 23 and May 22. The lowest temperature was — 8 C
(17 F), with an average of 70 days with frost each winter.

' This study was supported by Federal Aid in Wildlife Restoration Projects W-52-R "Wildlife Laboratory" and
W-47-R "Upland Came Investigations." Accepted for publication December 1975.

CALIFORNIA FISH AND CAME

WESTERN GRAY SQUIRREL

Squirrel Range

O
A

Principal Collection Areas, 1968 — 70

Supplemental Collection Areas, 1968—70
Principol Collection Areos, 1963-68
Supplennental Collection Areas, 1963— 68

FIGURE 1. Collecting areas and range of the western gray squirrel in California.

WESTERN CRAY SQUIRREL FOOD HABITS 13

Kern Collection Area

The Kern sample was taken in the Greenhorn Range and on Breckenridge
Mountain, in the southern tip of the Sierras, approximately 35 miles east of
Bakersfield. The terrain varies from rolling hills to steep canyons. At lower
elevations the forest association consists of blue oak, California buckeye and
digger pine (Pinus sabiniana). In both study areas, which are about 1,219 to
1,524 m (4,000 to 5,000 ft) in elevation, yellow pine {Pinus ponderosa) is the
dominant tree, along with sugar pine {Pinus lambertiana) . Incense cedar (
Calocedrus decurrens) is common in the Greenhorn Range, but noticeably
absent on Breckenridge Mountain. White fir {Abies concolor) is found in both
areas. Black oak is common in both areas and is well distributed throughout the
yellow pine association.

The highest rainfall in Kern County, ranging from 50 to 60 cm (20 to 25 inches)
a year, falls on the slopes of the Greenhorn Range and Breckenridge Mountain.
Most precipitation occurs in winter with snow at the higher elevations. Summer
thunderstorms occur, but are not common. Freezing temperatures usually start
in early October and persist as late as May, sometimes reaching below 0 F.
Summer temperatures average 21 C (69 F), with extremes over 32 C (90 F)
unusual. The average annual temperature is 13 C (55 F).

SAMPLES AND METHODS
A total of 207 gray squirrel stomach samples were analyzed from Kern County.
The squirrels were collected by shooting from December, 1968 through Decem-
ber, 1970. From the University of California Hopland Field Station in Mendocino
County, 68 gray squirrel stomach samples were analyzed and were collected
from May, 1969 through April, 1970. Supplementary collections were made from
the following counties: Sonoma (31), Napa (4), Tehama (7) and Shasta (3).
The method of analysis is described in a previous paper (Stienecker and Brown-
ing 1970).

RESULTS
Food habits analyses of the Kern and Mendocino samples show that hypo-
geous fungi, acorns, pine nuts, California bay fruit and vegetative leaf and stem
fragments were the staple food items eaten by the western gray squirrels. These
five food items contributed 95% of the total items eaten by Kern County squirrels
(Table 1 ) and 90% of the items eaten by squirrels in Mendocino County (Table
2). The 31 Sonoma County squirrels (Table 3) selected 99% of their food from
the above five items. The food samples from Napa, Shasta and Tehama counties
indicated a similar pattern (Table 3).

CALIFORNIA FISH AND CAME

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Fungi, Hypogeous --

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Mistletoe If. Phoradendron sp - --

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Dry pine needle fgmts. Pinus sp

Rootlet fgmts

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Pitch (amber, hard)

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CALIFORNIA FISH AND CAME

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CALIFORNIA FISH AND CAME

TABLE 3. Food Items Eaten by 45 Western Gray Squirrels— Sonoma, Tehama, Napa and
Shasta Counties, 1%9

Sonoma (31)
November

Tehama (7)
October

Napa (4)
October

Shasta (3)
November

California bay fruit Umbellularia californica

Funei Hvooeeous

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Acorn fgmts. Qwercus sp. -

Poison oak sd. Rhus diversiloba

Unidentified fruit and seed

Pine nuts Pinus sp

Gall fragments --

Unidentified matter _

Fungi Epigeous

Woody and bark fragments-- - _

Fir needle fragments

Rootlet fragments -

Incense cedar leafage Calocedrus decurrens

Animal matter ._ _

Fungi

In both principal collection areas hypogeous fungi were the most important
food items eaten. In the Kern County sample the yearly average volume eaten
was 48%. Fungi were eaten every month of the year, with the highest consump-
tion in July (90%) and the lowest in February, September and October (25%
each ) . In Mendocino County the yearly average volume of fungi consumed was
45.5%. Again July was high (82%) and September (15%) the lowest.

Several fungi of the order Turberales, or truffles, were important food items
in both principal study areas, and occurred in the sample every month of the
year. Rhizopogon, a false truffle in the Basidiomycetes group, was also important
in Kern County, but did not occur in the Mendocino sample. Other Basidi-
omycetes fungi found on both areas were, in the order of their importance (by
frequency of occurrence): Melanogaster, Gautiera and Hysterangium. This
group of fungi occurred most often in the diet from April to August.

Several kinds of epigeous fungi were found in the squirrel stomachs analyzed.
Puffballs (Order Lycoperdales) and gill mushrooms were utilized. On the Kern
County study area, epigeous fungi appeared in the analyses each month except
February, March and September and occurred less often in the Mendocino
County sample.

Fungi was also the most significant food item of the squirrels in the supplemen-
tary collection areas of Shasta and Tehama counties, although second in impor-
tance in Napa and Sonoma counties. Tuberales and Rhizopogon a^dAn were the
fungi most commonly selected. Puffballs and gill mushrooms also were eaten in
Sonoma County.

Acorns

Acorn mast was second in importance and was eaten every month of the year
in both study areas. In Kern County acorns made up 35% of the total annual diet
of 207 gray squirrels collected between December, 1968 to December, 1970.
Acorn use was highest in February (69%) and lowest in July (3%). In 1970
acorns made up over 50% of the squirrels' diet for every month except June,
July and August. In June and August acorns were still over 25% of the total diet.

In Mendocino County, where oak was the predominant tree cover, yearly use

WESTERN CRAY SQUIRREL FOOD HABITS 19

of acorns was 38% of the total diet. The highest use of acorns was in January
(75%) and the lowest was in May (5%). Sample size probably accounts for
the wide range in amounts eaten. For each of 8 months, acorns made up 30%
of the Mendocino squirrels' diet, the spring and summer ( May through August),
again being the period of low acorn consumption.

In the Sonoma County sample, acorns made up 9% of the diet in November.
Oak mast fragments also appeared in the smaller sample of squirrels from Napa
and Tehama counties.

Pine Nuts

In Kern County, pine nuts were only 10% of the total annual diet. Pine seeds
became an important item in the diet during the months of August (32%),
September (29%) and October (27%), making pine nuts the third most impor-
tant food item in Kern County. Pine nuts did not show up in the stomach samples
from Mendocino County study area; made up less than 1% of the total food in
Sonoma county and did not appear in the collections from the other three
counties.

California Bay

Bay fruit appeared in the squirrel diet in Mendocino county, where it made
I up nearly 6% of the annual diet. Bay fruit appeared in the diet only in 4 months
I of the year, the highest consumption occurring in June (20%), August (40%)
I and September (43%). In the November collection of 35 samples from Sonoma
I and Napa counties, bay made up almost 60% of the total food eaten. It did not

show up in the Kern County study, or in the small number of samples from

Tehama and Shasta counties.

I Green Vegetation

The leafage and stems of grass and forbs were eaten by gray squirrels every
month of the year in Kern County, averaging 2% of the diet for the whole year;
use of green feed reached a peak in June. Miners' lettuce {Montia sp.), leafage
and seed, was eaten each month from February through June, being highest
(5%) in February. Less than 1% of the total annual diet in Mendocino County
was made up of green vegetation. However, green vegetative fragments which
showed up 9 months of the year were the highest (1.8%) in May.

Other Foods

Animal matter was a significant food item in stomachs collected in Mendocino
County. Insects and larvae appeared at least as trace items every month of the
year. The highest percentages were consumed in March (16.5%), May (15%),
June (13%) and September (12%). In Kern County, animal matter occurred In
1 1 months of the year, not appearing in December. However, there were only
3 months when animal matter was more than a trace item; March (4%), April
(3%) and September (7%).

In Mendocino county walnut [Juglans sp.) fragments were found in the diet
in October (37.5%). Filareeseed {Erodiumsp.) was important in May (27.5%),
comprising 70% and 95% in each of two stomachs collected on the Hopland
Field Station.

In recent studies of the western gray squirrel on the western slopes of the
Sierra Mountains (El Dorado County) gray squirrels were observed stripping

20 CALIFORNIA FISH AND GAME

virtually every cone off a sugar pine tree over a period of ly^ weeks (Crase
1970). Black oak leaf buds have also been recorded as an important part of the
gray squirrels' diet during a 4 week period in April, also in El Dorado County
(Peterson 1971).

DISCUSSION

Fungi

Hypogeous fungi are staple foods of the western gray squirrel over much of
its distribution. The percent of fungi utilized annually for each area is as follows:
Kern (48%), Mendocino (44%), Trinity (58%), Tehama (58%) and Monterey
(37%). The same is true for the supplemental collection areas — Napa-Sonoma
counties (28%); the central Sierra area (50%) and Humboldt County (37%)
(Stienecker and Browning 1970).

Hypogeous fungi are important foods not only for the western gray squirrel,
but for other sciurids as well; such as the Douglas squirrel ( Tamiasciurus dou-
glasif), chipmunks {Eutamias sp.), golden-mantled ground squirrels (Citellus
lateralis) and Beechey ground squirrel {Otospermophilus) (Tevis 1952, 1953);
Kaibab {Sciurus kaibabensis) and Abert (5. aberti) squirrels (Keith 1965).

Although hypogeous fungi are the main food items of the gray squirrel
throughout the Sierras and the northern and central Coastal Ranges, the kind and
variety of fungi varies with the forest association where the squirrel seeks its
food. In the Mendocino County study area, which is mostly oak-woodland, the
Tuberales fungi are predominant with no representative of the Rhizopogoniun%\
in the diet. In the Kern County area, which is a conifer-oak association, the
Rhizopogon fungi, which are associated with conifer litter (Smith and Zeller
1966), are predominant in the diet. Generally, however, there is greater variety
of fungi in the diet of the squirrels taken from the conifer-oak association.

There is a seasonal pattern to the use of fungi throughout the western gray
squirrel's distribution. Tuberales (the truffles) are utilized every month of the
year in both Kern and Mendocino counties. Rhizopogon (false truffles) which
did not occur in the diet of the Mendocino County sample, occurred each month
in the diet of the Kern County squirrels; however, fungi consumption is highest
through the spring and early summer. False truffles, particularly Rhizopogon,
Gautiera, Histerangium, and Melanogaster, tend to be used more in the summer
months and in some areas truffles more in the fall months.

Gray squirrels apparently are attracted to and consume an amazing variety of
both hypogeous and epigeous fungi. Over 25 different fungi spores were isolated
and identified, at least to Order. The Tuberales group showed the greatest variety
(10 or more), while Rhizopogon, Gautiera, Histerangium, Melanogaster dx^^A
Lycoperdales vjexe represented by two to three kinds of spores each. Epigeous
fungi were represented by species of Agaricus, Boletus and the puffballs.

Acorns

Oak mast is an important food, and makes up as much as a third of the total
yearly diet of the western gray squirrel over much of its range. Acorn consump-
tion also follows a strong seasonal pattern, most in the late fall and early winter
and least in the summer. The Kern County results indicate that gray squirrels will
respond to a good acorn crop. Percentages of acorns in the diet were notably
higher in the Kern results. There were bumper acorn crops on the Kern study

WESTERN GRAY SQUIRREL FOOD HABITS 21

areas in 1969 and 1970. Weather apparently is the key to a good mast crop and
hence to the annount of acorns used by gray squirrels during a given year. Acorns
are probably a "key" food for the western gray squirrel since good fall foods
contribute to the condition of the animal prior to over-wintering (Stienecker and
Browning 1970).

Pine Nuts
The nuts of several kinds of pines are another very significant gray squirrel
food item. The quantity of pine nuts consumed by squirrels in Kern County was
less than the amount eaten by the gray squirrels throughout the rest of the state,
but the pattern of use remained the same. Gray squirrels cut and strip cones and
use the nuts when they are in the "milk" stage. Pine nuts are found in the diet
from mid-summer on into the fall.

California Bay

On several study areas (Monterey, Mendocino and Sonoma counties), bay
fruit contributed heavily to the diet. Gray squirrels tend to feed on bay fruit from
the fall through early spring, a similar use pattern to that of acorns.

ACKNOWLEDGMENTS
I wish to express appreciation to Department personnel, W. C. Graves and W.
C. Asserson for collection of the squirrel samples from Kern County and for
helpful comments on the manuscripts. Thanks are due to Guy Connolly who
collected samples from the University of California Field Station at Hopland in
Mendocino County. Special appreciation is given to Bruce Browning for his
encouragement and direction, and help to identify some of the food items.

REFERENCES

Asserson III, W. C, 1974. Western gray squirrel study in Kern County, California. Calif. Dept of Fish and Came
Admin. Rep., 74-1.

Crase, Fred. 1970. Food and feeding habits of the western gray squirrel. El Dorado County. Master thesis. Calif.
State Univ., Sacramento.

Keith, |. O. 1%5. The Abert squirrel and its dependence on ponderosa pine. Ecology, 46(1 and 2): 150-163.

McKeever, S. 1964. Food habits of the pine squirrel in northeastern California. ). Wildl. Manage., 28(2):

402-403.
Peterson, D. 1 970. Observations on the food habits of the western gray squirrel. Term paper. Calif. State Univ.,

Sacramento.
Stienecker and Browning. 1970. Food habits of the western gray squirrel. Calif. Fish Came, 56(1): 36-48.
Sudsworth, George B. 1908. Forest trees of the Pacific slope. U.S.D.A., Forest Service publ. 438 p.
Tevis, L., Jr. 1952. Autumn foods of chipmunks and golden-mantled ground squirrels in the northern Sierra

Nevada. Mammal., 33(2): 198-205.

Calif. Fish and Came, 63 ( 1 ) : 22-28. 1 977

EFFECTS OF SALINITY ON LARVAL GROWTH IN THE
CALIFORNIA KILLIFISH, FUNDULUS PARVIPINNIS

GIRARD'

Teegavarapu R. Rao ^

Department of Population and Environmental Biology

University of California, Irvine, California 92664

California killifish, (Fundulus parvipinnis) larvae, incubated and hatched in salini-
ties of 5, 14, 33, and 55%,, were reared for 10 weeks in their respective incubation
salinities. Larvae and juveniles were fed live Artemia nauplii once daily (,ad libi-
tum). Length, wet weight, and dry weight of randomly sampled larvae were deter-
mined at 15-day intervals. Growth rates of the larvae were highest in 55 and lowest
in 5%o S. it is suggested that the observed differences in growth rates were related
to the probable influence of salinity on food intake and conversion efficiency of the
larvae.

INTRODUCTION

The California killifish, Fundulus parvipinnisG\rd^rd, although euryhaline (Keys
1930, Feldmeth and Wagoner 1972), is generally found in bays and lagoons
along the coasts of Southern California and northern Baja California. Its occa-
sional occurrence in completely freshwater habitats has been reported by Miller
( 1 943 ) who observed that the average size of adult killifish from fresh water was
smaller than that of the killifish from marine waters.

There is considerable field information (Canagaratnam 1959, Gunter 1961,
Holliday 1971 ) and experimental evidence (Gibson and Hirst 1955, Kinne 1960,
Holliday 1971, Weatherly 1972) suggesting that growth and size of euryhaline
fishes is influenced by salinity. Salinity may affect growth through its influence
on food intake, conversion efficiency and activity, which are important compo-
nents of the bioenergetic budget of fishes (Paloheimo and Dickie 1966, Warren
and Davis 1967).

There is no published information on the effects of environmental factors such
as salinity on the growth of California killifish, particularly during the early stages
of its life. This paper reports the effects of salinity on growth of killifish larvae
raised in the laboratory and is part of a broader study of the role of salinity in
the physiology and ecology of F. parvipinnis (Rao 1972).

MATERIAL AND METHODS

Killifish larvae were hatched in the laboratory under controlled temperature-
salinity conditions. Methods of fertilization and incubation are described else-
where (Rao 1974). Larvae were obtained from eggs fertilized in 33 %o S (salinity)
and incubated in either 5, 14, 33, or 55 %» S.

Approximately 50 active, newly hatched larvae from each of the incubation
salinities were transferred in two replicates to 3.5 I (1 gal) glass jars containing
water of the same salinity as that of incubation. Lower salinities were prepared
by adding dechlorinated tap water to natural sea water, higher salinities by

' Extracted from a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of

Philosophy at the University of California, Irvine, 1972.
' Present address: Hawaii Institute of Marine Biology, P. O. Box 1346, Kaneohe, Hawaii %744

SALINITY EFFECTS ON KILLIFISH LARVAL GROWTH 23

adding synthetic sea salts. Cultures were maintained at a constant temperature
of 21 ± 1 C (69.8 ± 1.8 F) and a light regime of 14 hours and 10 hours darkness
throughout the experiment. The water in each jar was aerated continuously and
exchanged every 3 days with fresh medium of appropriate salinity. Larvae and
juveniles were fed live brine shrimp {Artemia) nauplii once daily {ad libitum)
except on the day prior to weighing. The different salinities in the test jars had
no observable effect on behavior of the nauplii or on their availability as food
for the larvae. There were generally some nauplii left uneaten after each feeding,
indicating that the larvae had fed to satiation. Unconsumed food and fecal
matter were removed from the jars daily.

Total length, wet weight, and dry weight of five to eight randomly selected
larvae from each jar were determined at 15-day intervals. Larvae were anesthe-
tized in tricaine methanesulfonate (MS 222, 0.1 g/liter) and measured with a
binocular microscope and ocular micrometer. During the latter stages of the
experiment, the fish were measured with dial-reading calipers to the nearest 0.05
mm (1.97 X 10"^ inch). Wet weights of the fish were determined to the nearest
0.1 mg (3.53 X 10~* oz). To obtain dry weights, anesthetized larvae were first
rinsed in distilled water to remove any external salts; then they were oven-dried
at80C (176 F) for 12 hours, and then at 105 C (221 F) until weight constancy
was achieved. Initial and final measurements were taken on the 10th and 70th
day after hatching, respectively. Removal and sacrifice of larval samples at
15-day intervals helped to maintain in each container a nearly constant ratio of
biomass to volume of water throughout the test period.

Length-weight relations for the larvae reared in different salinities were exam-
ined to determine the possible influence of salinity on the 'condition' of the
larvae (Tesch 1968).

RESULTS

Larval mortality during the test period was negligible ( <5%) in 14, 33, and
55 %o S; it was high ( >80%) in 5% S. Consequently, relatively small samples
were available for determination of growth rates in 5%o S and no larvae were
available for sampling beyond the 40th day. Larval mortality in 5%o S apparently
was size-selective with smaller individuals succumbing earlier than larger fish.
The heavy mortality was caused by the lowered resistance of killifish larvae to
extremely low salinities (Rao 1975).

A preliminary covariance analysis showed that differences in the observed
growth rates between replicates were not statistically significant for any test
salinity ( p > 0.25 ) , justifying a pooling of data from replicates for further analysis.

Larval growth, in terms of increase in total length, showed a linear relationship
in all salinities (Figure 1 ). Although differences in the age-length regression lines
of different salinities were not statistically significant, a trend was evident in
which lowest growth rates occurred in 5% S, while highest rates occurred in
55%. S.

Increase in dry weight of larvae with age in different salinities is presented in
Table 1. The relation between age and dry weight appears to be sigmoidal
(Figure 2). There were no well-defined trends evident in the initial stages of
growth. Later stages showed trends similar to those found in the age-length
relation. Maximum growth rates occurred in 55%. S, and the final dry weights
achieved by fish grown in salinities of 14, 33, and 55Voo S showed significant
differences (p<0.05).

CALIFORNIA FISH AND CAME

Z
LlJ

I-

5%o

15) /

■

(5)/

Y=6 46I + 02I6IX

1 1 1

10 25 40 55 70

AGE(days offer hafching)

<
o

10 25 40 55 70

AGE(days offer hafching)

25 _

I-

33%<

(14)

HI-/

(15)
/

Y=6 691 + 02225 X

-J L.

10 25 40 55 70

AGE ((joys offer hofching)

I
I-
« 15

iij

_l
?

I-

(10)/

55%.

((0)

(10)/

(10)

Y=7 055 + 0.2392 X

_1 L

10 25 40 55

AGE((]oys offer hotchir^g)

Figure 1. Age-total length relation in killifish larvae reared in different salinities. Regression lines
were drawn using the given equations. At each observation point, the symbols represent
range and ± one standard error. Sample size is given in parenthesis.

SALINITY EFFECTS ON KILLIFISH LARVAL GROWTH

TABLE 1. Growth of Killifish Larvae in Different Salinities. Mean dry weight in milligrams,
Cx), standard error (SE), and sample size (N) are shown for larvae at different
ages in different salinities.

Salinity

(°/

jo)

Age

(days after

hatching)

SE N

1.11

0.035 9

1.16

0.037

1.23

0.042

1.07

0.047

3.62

0.124 5

3.05

0.221

2.46

0.111

3.58

0.321

7.26

0.271 5

6.50

0.353

6.91

0.358

8.19

0.248

- -

18.19

0.673

16.55

0.648

18.68

1.214

- -

24.19

0.846

21.95

0.873

26.87

1.509

27
24

: o^ 18

i E

(3
LiJ

9
6

3 _

SALINITY (%o)

-A- 5

-o 14

_^-. 33

_•_ 55

•

/
•

!¥

/ ••■ ''

/ •■ ^

/ ' ^

■1

•'/

AGE(days after hatching)

Figure 2. Age-dry weight relation in larvae reared in different salinities. Each point represents the
mean of 8-15 individuals (see also Table 1 ).

CALIFORNIA FISH AND CAME

The length (L)-weight (W) relations for larvae grown in the test salinities
(Figure 3) are described by the equation:

Log W = Log a + b (Log L)

Covariance analysis showed the Slope (b) in 5%o S to differ significantly (p<
0.05) from that in salinities of 33 and 55%o- However, at the end of the experi-
ment, there were no significant differences (p — 0.47) in the condition factor
(dry weight/total lengths for larvae grown in salinities 14, 33, and 55%oS.

Log Y =

-3.227+ 3 491 LogX

1 1

1 , ,•*! 1

5%o

1 '

5 10 20 30

TOTAL LENGTH(mm)

— 20

X
(3

Log Y= -3 133 + 3.364- Log X

_J L.

14%.

5 10 20 30

TOTAL LENGTH(mm)

LogY =

-2 401+ 2773

LogX

1 1

33%.,
1 1

5 10 20 30

TOTAL LENGTH(mm)

I-
I
O 10

Log Y= -3 023+ 3 281 Log X

_i I I I tT» I

55%,

5 10 20 30

TOTAL LENGTH(mm)

Figure 3. Total length-dry weight relation of larvae reared in test salinities. Each circle represents
one individual. Regression lines were drawn using equations given in the figure.

SALINITY EFFECTS ON KILLIFISH LARVAL GROWTH 27

DISCUSSION

The size-selective mortality of larvae grown in 5 %„ S may have introduced bias
into the growth data obtained in the present study. Such a pattern would result,
at any given stage, in a higher proportion of larger individuals remaining than
if mortality had been size-independent. This possible bias and the relatively small
sample size in 5%o may account for the lack of statistical significance among the
different growth rates compared. A similar bias may also have influenced the
data on length-weight relations of the larvae. Despite these statistical shortcom-
ings, two interesting trends emerge from the present study: ( 1 ) The growth rates
of larvae of Fundulus parvipinnis were lower in very low salinities ( < 5% S),
and (2) maximum growth was associated with the 55 %» S hypersaline medium!
I have observed similar salinity-related trends in the growth of pre-adults of the
same species ( Rao 1 972 ) . Although there is considerable field and experimental
evidence indicating lower growth rates of euryhaline fishes in low salinities
(Canagaratnam 1959; Holliday 1971), reports of enhanced growth of fish in
hypersaline water, as observed in the present study are less common. In growth
studies by Kinne (1960) on the desert pupfish, Cyprinodon macu/ar/us and by
Feltkamp and Kristensen (1970) on the molly, Poecilia sphenops, growth rates
were lower in salinities above 35%o S.

It has been suggested that the influence of salinity on growth may be explained
in terms of the energetic cost of osmoregulation (Canagaratnam 1959). Os-
moregulation, like other metabolic processes of organisms, involves energy ex-
penditure; the relationship of this energy expenditure to the growth budget of
euryhaline fishes is not well understood (Holliday 1971). The energetic cost of
osmoregulation appears to be slight in certain species (Lasker and Theilacker
1962), but substantial in others (Rao 1968). Brett (1970), based on survey of
pertinent literature, concludes that "except in the estuary, any advantage which
the marine environment might confer on growth, through the energy-saving
mechanism of reduced osmoregulation, would be small."

Oxygen consumption by Fundulus larvae was less in fresh water and 55% S,
both stressful salinities, than in normal sea water (Rao 1972). Thus, it is unlikely
that the bioenergetic cost of osmoregulation has contributed significantly to the
growth differences observed among larvae grown in different salinities. No data
are available on the activity patterns of the larvae which might be influenced by
the variations in buoyancy caused by salinity.

I suggest that possible differences in food intake and food conversion effi-
ciency were primarily responsible for the observed growth differences. Although
larval food intake was not quantified in my experiments, routine observations
indicated a consistently higher food intake by larvae grown in 55%., S. The lower
growth rates observed in salinities approaching fresh water are probably due to
decreased food intake and low food conversion efficiency. Differences in food
intake and conversion efficiency at various salinities have been demonstrated in
coho salmon, Oncorhynchus kisutch by Otto (1971) and in desert pupfish,
Cyprinodon macularius by Kinne (1960).

The present study suggests a salinity range (ca. 10-40 %„ S) in which larval
growth is not significantly influenced by salinity; however, salinities close to fresh
water do not favor rapid growth. Miller (1943) noted differences in growth and
size between individuals of marine and fresh water populations of the California
killifish and suggested that habitat salinity might be the primary causative factor.

28 CALIFORNIA FISH AND CAME

Although possible differences in the availability of food resources in marine
versus fresh water habitats and genetic differences in food conversion efficien-
cies between marine and fresh water killifish populations can not be ignored in
explaining observed size differences of killifish in Miller's study, the suggestion
that habitat salinity is the major factor, is experimentally supported in the present
study.

ACKNOWLEDGMENTS

I express my grateful appreciation to R. E. MacMillen, R. S. Seapy, and R. H.

Rosenblatt for their guidance and support. Don Alderdice, Pacific Biological

Station, Nanaimo, B. C, Canada and Robert May, Hawaii Institute of Marine

Biology, Kaneohe, Hawaii, made many helpful comments on an earlier draft.

REFERENCES

Brett, J. R. 1970. Fish — The energy cost of living. Pages 37-52 //? W. J. McNeil, ed.. Marine aquaculture. Oregon

St. Univ. Press, Corvallis.
Canagaratnam, P. 1959. Growth of fishes in different salinities. Can. Fish. Res. Bd., )our, 16(a): 121-130.

Feldmeth, C. R., and ). P Wagoner, III, 1972. Field measurements of tolerance to extreme hypersalinity in the

California killifish, Fundulus parvipinnis. Copeia, 1972(3): 592-594.
Feltkamp, C. A., and I. Kristensen 1970. Ecology and morphological characters of different populations of

Poecilia sphenops vandepolli (Cyprinodontidae). Stud. Fauna Curasao, 32; 102-130.

Gibson, M. B., and B. Hirst. 1955. The effect of salinity and temperature on the pre-adult growth of guppies.

Copeia, 1955 (3): 241-243.
Gunter, G. 1961. Salinity and size in marine fishes. Copeia, 1961 (2): 234-235.

Holliday, F. G. T. 1971. Salinity: animals: fishes. Pages 997-1083 inO. Kinne, ed.. Marine ecology. Vol. 1, Pt.

2. Wiley-lnterscience, London.
Keys, A. B. 1930. A study of the selective action of decreased salinity and asphyxiation on the Pacific killifish,

Fundulus parvipinnis. Bull. Scripps Inst. Oceanogr., n.s. 2: 417-490.
Kinne, O. 1960. Growth, food intake, and food conversion in a euryplastic fish exposed to different tempera-
tures and salinities. Physiol. Zool., 33: 288-317.
Lasker, R., and G. Theilacker. 1962. Oxygen consumption and osmoregulation by single Pacific sardine eggs

and larvae iSardlnops caerulea Girard). lour. Cons. Perm. Int. Explor. Mer, 2: 25-33.
Miller, R. R. 1943. Further data on freshwater populations of the Pacific killifish, Fundulus parvipinnis. Copeia,

1943(1): 51-52.
Otto, R. G. 1971. Effects of salinity on the survival and growth of presmolt coho salmon (Oncorhynchus

kisutch). Can. Fish Res. Bd., lour, 28(3): 343-349.
Paloheimo, |. E., and L. M. Dickie. 1966. Food and growth of fishes. III. Relations among food, body size, and

growth efficiency. Can. Fish. Res. Bd., )our., 23(8): 1209-1248.
Rao, C. M. M. 1968. Oxygen consumption of rainbow trout (Salmogairdneri) in relation to activity and salinity.

Can. lour. Zool., 46(4): 781-786.
Rao, T. R. 1972. Experimental studies on the influence of salinity on the life history and distribution of the Pacific

killifish, Fundulus parvipinnis Girard. Ph.D. dissertation, Univ. Calif., Irvine.
1974. Influence of salinity on the eggs and larvae of the California killifish, Fundulus parvipinnis. Mar.

Biol., 24: 155-162.

1975. Salinity tolerance of laboratory-reared larvae of the California killifish, Fundulus parvipinnis

Girard. lour. Fish. Biol., 7(6): 783-790.
Tesch, F. W. 1968. Age and growth. Pages 93-1 20 />7W. E. Ricker,ed. Methods for assessment of fish production

in fresh waters. IBP Handbook No. 3, Blackwell Sci. Publ., Oxford.
Warren, C. E., and G. E. Davis. 1967. Laboratory studies on feeding, bioenergetics, and growth. Pages 175-214

in S. D. Gerking, ed. The biological basis of freshwater fish production. Blackwell Sci. Publ., Oxford.
Weatherly, A. H. 1972. Growth and ecology of fish populations. Academic Press, New York. 303 p.

^Calif. Fish and Came 63 ( 1 ) : 29-42, 1977.

' DETECTION OF DELAYED ANNULUS FORMATION

AMONG BLUEGILL,

LEPOMIS MACROCHIRUS, POPULATIONS AT

LAKE NACIMIENTO, CALIFORNIA ^

I DELORES BROWN ^, EDWARD E. MILLER ^

and C. E. VON CELDERN, JR.

Inland Fisheries Branch
California Department of Fish and Came

! Age and growth studies of centrarchid populations are sometimes based on as-

, sumptions concerning the presence or absence of current annuli. This report exam-

ines the relationship of size and age of bluegill to time of annulus formation and
^ considers a procedure for helping determine if current annuli are present.

INTRODUCTION

Fisheries management decisions regarding bluegill populations are often based

on an analysis of age and growth characteristics. The scale method of aging is

commonly used in California (La Faunce, Kimsey, and Chadwick 1964, Tharratt

1966, Miller 1971 ) and the validity of this technique has received a degree of

igeneral acceptance (Regier 1962, Serns and Strawn 1975).

Scale samples from angler caught bluegill at Lake Nacimiento were routinely
collected and aged from 1965 through 1968 as part of an overall evaluation of
an experimental introduction of threadfin shad (Dorosoma petenense) and
white bass (Morons chrysops) on the Lake Nacimiento fishery. This report
describes the analysis of these collections with respect to age and considers a
technique for helping determine the completeness of formation of the current
year's annulus among aggregations of scale samples containing a similar number
of annuli. Lake Nacimiento has been described elsewhere (von Geldern 1971 )
and we need only note here that this 2,145-ha (5,300-acre) impoundment is
located in San Luis Obispo County and contains an attractive warmwater fishery
supported largely by black crappie (Pomoxis nigromaculatus), largemouth bass
(Micropterus salmoides), bluegill, and white bass.

SCALE COLLECTION AND ANALYSIS
All scale samples used for these analyses were obtained from angler-caught
fish in July of each study year (1965-1968) in conjunction with an extensive
roving creel census (von Geldern and Tomlinson 1973). Six to 10 scales were
removed from each bluegill at a point near the tip of the left pectoral fin ( Proffitt
1950) and placed in individual coin envelopes marked with length of fish (fl)
to the nearest 2.5 mm (0.1 inch). Scale impressions were made on cellulose
acetate strips of 1 .0-mm (0.04-inch ) thickness with a Model B Carver Laboratory
Press and examined with the aid of an Eberbach scale projector providing a
magnification of 42 X. A total of 1,012 usable scale samples was collected over

' Accepted for publication January 1976. This work was performed as part of Dingell-Johnson Project California

F-18-R, "Experimental Reservoir Management", supported by Federal Aid to Fish Restoration funds.
' Present address: 5325 Marconi Ave, Apt. No. 72, Carmichael, California 95608
' Present address: California Department of Fish and Came P. O. Box 131, Lewiston, California 96052

30 CALIFORNIA FISH AND CAME

the Study period. Yearly sample sizes ranged from a high of 303 in 1967 to a low
of 182 in 1968 (Table 1).

TABLE 1. Number of Annul! Present on Bluegill Scales from
Lake Nacimiento, 1%5-1968.

Number of bluegill sampled

Annul! present 1965 1966 T967 T968 TotaTs

1 36 18 11 0 65

II 169 251 240 60 720

III 24 26 51 109 210

IV 0 3 0 12 15

V 0 0 _[ 1^ 2

Totals 229 298 303 182 1,012

Scale samples for each study year were first segregated according to number
of annuli present following criteria for annuli recognition developed by Regier
(1962). Yearly collections were dominated by scales with two annuli from
1965-1967 while scales with three annuli were most prevalent in 1968.

Inherent in the sampling design was the assumption that the current year's
annulus would be present on bluegill scales collected in July. This assumption
was based in part on generalizations set forth by Regier (1962) indicating that
time of annulus formation among normally growing bluegill populations is rough-
ly a function of latitude and ranges from late April at 38°N to late June at 46°N.
Lake Nacimiento is located at lat 35°40'N in the extremely warm Salinas Valley
and was known to contain an abundant (and assumed normally growing)
bluegill population which provided attractive angling. These considerations
formed the basis for our initial judgment that July sampling would provide
bluegill scales with recognizable annuli for the current year.

Preliminary inspection of cohorts of scales containing a similar number of
annuli in a given year revealed broad variation with respect to placement of the
outermost annulus. On some scales, the outer annulus was marginal or nearly
so while others showed an outer annulus at a far more central location (Figure
1 ) . Such variations in annuli placement reflect extreme growth variability among
cohort members if outer annuli are assumed to have been laid down in the
current year. These observations caused us to re-examine our initial premise that
the current year's annulus would invariably be present on bluegill scales sampled
in July.

A regularly recorded characteristic of bluegill populations is the pronunced
tendency of young specimens to form annuli and resume spring growth earlier
than their older counterparts (Bennett, Thompson, and Parr 1940, Lane 1954,
Gerking 1966). This phenomenon has been noted for other species (Hodgson
1925, Hile 1941, Stroud 1948) and often applies not only to absolute chronologi-
cal age but also to size within an age cohort; i.e., small fish form annuli earlier
than larger ones of the same age (Frey 1942, Smith 1956, Bailey 1964, Gerking
1966) . While this feature of spring growth resumption does not appear universal
among all fish species of all ages in all types of environments (McFadden 1959,
Rothschild 1 963 ) , no evidence to the contrary regarding bluegill populations has
been recorded.

The tendency of young bluegill to form annuli early in the growing season is
coupled with a relatively rapid rate of linear growth (Gerking 1966). Clearly, the
ratio of yearly incremental growth to total growth experience (as recorded on

BLUECILL DELAYED ANNULUS FORMATION

'A^-fc,.-- :->,*.

'"^"^ffi^r"^--

\-^xmf^/4

FIGURE 1 , Photographs of bluegill scales showing variation in the placement of outer annuli. Scale
A is from a 14.5-cm specimen collected in 1965 with an outer annulus at a central
location as compared with scale B from a 20.0-cm bluegill obtained in the same year.
Scales C (12.4 cm) and D (13.0 cm) were collected in 1966 and scales E (13.0 cm)
and F (14.7 cm) were obtained in 1968. Arrows depict annuli.

scales) must be greatest among younger specimens of mixed age groups and/or
smaller individuals of a given age cohort. By inference, it follows that such ratios
must be negatively correlated with fish length among aggregations of scales with
i current annuli for a given year.

I These observations formed the rationale for a "test" designed to help deter-
I mine the completeness of annulus formation among groups of scales with a
similar number of annuli. The ratio (Y/X), where

CALIFORNIA FISH AND CAME

Y = the distance along the primary radius of the projected scale image from
the outermost annulus to the anterior scale margin and

X = the distance from the center of the focus to the anterior scale margin,
was calculated for each bluegill sampled and plotted against fish length. Graphic
plots were constructed for all groups of scales with the same number of annuli
for each study year and critically examined with respect to the assumed inverse
relationship between ratio (Y/X) and fish length.

Examples of Complete Annulus Formation

Graphic ratio (Y/X) and fish length relationships for bluegill scales with one
and two annuli collected in 1966 are used to illustrate a case where formation
of the current year's annulus was judged complete (Figure 2). The inverse
relationship between (Y/X) values and fish length is clearly evident and applies
not only to age but also to length within an age cohort. Among Age I specimens,
fish less than the mean length of 8.9 cm (3.5 inches) had an average (Y/X) ratio
of 0.58 which while those longer than the mean had an average (Y/X) value
of 0.48. Age II specimens, which totally dominated the 1966 scale collection,
exhibited a similar relationship; mean (Y/X) ratios for various length groupings
ranged from a high of 0.38 for specimens less than 11.4 cm (4.5 inches) to a
low of 0.09 for those individuals over 16.5 cm (6.5 inches) (Figure 2).

.80
.70-
.60
.50
.40
.30
.20
.10
0

— • —

• • • • •

• • •

• • • • • •

• • • • •
• •• •• ••••

• • • •

• • • • • • •

• • • •

• • •

• • • •

• • • • • -

• • •• •••••

• •••••• •

•• •••• •

• • • •

• • • I * . *

• • • • • • •

_ • • • . • -

• » » ^ • • ••

. t • : .. * : •

• • • • •

• • • • • •

: ...

T 8 9

12 13 14 15
FORK LENGTH (CM)

16 17 18 19 20

FIGURE 2. Relationship of ratio of distance from outer annulus to anterior scale margin to distance
from focus to margin (Y/X) to fish length of Age I and II Lake Nacimiento bluegills in
1966.

BLUEGILL DELAYED ANNULUS FORMATION

All yearly scale samples showing a single annulus also exhibited a pronounced
inverse relationship between ( Y/X) values and fish length; annulus formation for
this age group was, accordingly, judged complete (Appendices 1 and 2). That
segment of the 1967 scale collection with two annuli showed a similar relation-
ship (Appendix 2) and this group was also judged to have completed annulus
formation for the current year.

In November 1972, a small collection of scales from angler caught bluegill was
obtained at Lake Nacimiento for the purpose of comparing (Y/X) ratios and fish
length relationships at (or near) the end of the growing season with those
observed in July. This sampling effort was based on the premise that completed
annulus formation for the current year could be assumed with near certainty for
bluegill collected during the fall months and that a graphic expression of (Y/X)

.50
.45
.40
.35
5.30
^ .25
.20

•

•
•

•

•
•

•

•
•

•

• •

•

•
•

1 1

•
1 1

•
1

•

.15
.10
.05

3 lU II

FORK LENGTH (CM)

FIGURE 3. Relationship of ratio of distance from outer annulus to anterior margin to distance from
focus to margin (Y/X) to fish length of bluegill collected at Lake Nacimiento in Novem-
ber 1972.

ratio and fish length relationships would serve as a useful check against our
interpretation of similar materials constructed from July sampling. While sample
sizes were small due to a scarcity of bluegill anglers in November, the inverse
relationship between incremental growth and fish length was clearly evident
( Figure 3 ) . This observation served to reinforce our initial judgement concerning
the appearance of such graphic relationships in situations where the current
year's annulus is completely formed.

Examples of Incomplete Annulus Formation
Based on a graphic analysis of ratio (Y/X) and fish length relationships, certain
segments of the Lake Nacimiento scale collection showed clear evidence of

CALIFORNIA FISH AND CAME

incomplete annulus formation. Scales with two annuli collected in 1968, for
example, produced an array of data points characterized by two nearly discrete
groupings (Figure 4). One group had a mean ratio (Y/X) of 0.23 and a mean
length 14.0 cm (5.5 inches) while the other had comparable values of 0.53 and
15.5 cm (6.1 inches). It is clear to us that the group of larger individuals were
Age III specimens which had not laid down the current year's annulus and that
(Y/X) values for this cohort reflect growth achieved during the previous year.

.80

.70 h

.60
.50
.40
.30
.20
.lOh

AGEJE

. AGEH

J L

FICURE4.

14 15 16 17

FORK LENGTH (CM)

Relationship of ratio of distance fronn outer annulus to anterior margin to distance from
focus to margin (Y/X) to fish length of bluegill with two annuli collected at Lake
Nacimiento in 1968. Dashed line separates two age groups.

A second example of incomplete annulus formation was detected when
graphic ratio (Y/X) and fish length relationships were plotted for bluegill scales
with three annuli collected in 1967. Two aggregations of data points, separated
by a clear path connecting coordinates (13.3, 0.35) and (18.0, 0.20) (Figure 5)
appear to represent two age groups. One group, judged to have completed
annulus formation in 1967, had a mean ratio (Y/X) of 0.21 and a mean length
of 15.5 cm (6.1 inches). The second group, believed to represent Age IV speci-
mens which had not formed current annuli, had a mean (Y/X) value of 0.35 and
a mean length of 16.3 cm (6.4 inches) (Figure 5).

Other segments of the Lake Nacimiento scale collection also showed evi-
dence of incomplete annulus formation although the separation of data points
into definitive age groups involved a degree of uncertainty. Scales with two
annuli collected in 1965 represent a case where a portion of the collection

BLUECILL DELAYED ANNULUS FORMATION 35

12 13 14 15 16 17 18 19

FORK LENGTH (CM)

FIGURE 5. Relationship of ratio of distance from outer annulus to anterior margin to distance from
focus to margin (Y/X) to fish length of bluegill with three annuli collected at Lake
Nacimiento in 1967. Dashed line separates two age groups.

proved extremely difficult to age (Figure 6). The path clear of data points
extending roughly from coordinates (14.0, 0.45) to (16.8, 0.20) is believed to
separate Age II and Age III specimens. In the absence of a more definitive
technique, an extension of this line tou/ard the abscissa was used to further
delineate the two age cohorts. We regard this procedure as arbitrary, however,
and cannot rigorously defend our judgments concerning the age of bluegill
depicted by data points near the extended line. Despite these misgivings, we
note that such uncertainties involve only a minor fraction of the 1965 bluegill
scale collection with two annuli ( Figure 6) . Specimens judged Age II had a mean
ratio (Y/X) of 0.22 and a mean length of 15.2 cm (6.0 inches), while those
judged Age III had comparable values of 0.25 and 17.3 cm (6.8 inches).

Bluegill scales with three annuli collected in 1968 produced an array of data
points with certain basic similarities to that constructed from the 1965 collection
with two annuli (Appendix 3, Figure 6). A path free of data points extended
through a portion of the array which required an arbitrary extension in order to
age the entire sample. Despite this difficulty, serious uncertainties involved only
a very small percentage of the 1968 collection. Other segments of the Lake
Nacimiento scale collection, comprised primarily of older individuals, were
difficult to age because of small sample sizes. Nonetheless, the technique herein
described was applied to these groups and we believe they were more accurate-
ly aged as a result (Appendices 1 and 2).

CALIFORNIA FISH AND CAME

DISCUSSION

The age structure of segments of the Lake Nacimiento bluegill scale collection,
as determined by these procedures, differed considerably from initial judgments
based solely on the number of annuli present. Scales with two annuli in 1965,
for example, comprised over 70% of the entire collection for that year (Table
1 ) although less than 50% were judged Age II (Table 2). Similarly, over 50%
of the 1968 collection with two annuli were judged Age ill and over 40% of the
1967 collection with three annuli were considered Age IV. In general, older age
groups were more significantly affected by the application of this technique than
younger cohorts; the entire Lake Nacimiento collection produced only 17 sam-
ples with four or more annuli although 85 individuals were assigned to age
groups IV and V (Tables 1 and 2).

TABLE 2. Age Structure of Bluegill Sampled at Lake Nacimiento, 1%5-1%8.

Number of bluegill sampled
Age 1965 7%6 1967 1968 TotaTs

I 36 18 11 0 65

II 110 251 240 18 619

III 79 19 30 115 243

IV 4 10* 21 40 75

V 0 0 _\\ 9t TO

Totals 229 298 303 182 1,012

* Specimens from this cohort with four annuli (three individuals) may be Age V.

t A specimen with five annuli which may be Age VI.

{ A single member of this cohort with five annuli may be Age VI.

.50

.45

.40

.35

g.30

^.25

i.20

.15

.10-

.05-

AGE in

• • •

• \ •

• • \ • •

• • • V*** •

• • • ^ • • •

• \ •

• ^^ •

• • • \,^ -~.^

AGEE

• !• • • ^ •

* \ • ^-^

. \ . . N

• • \

15 16

FORK LENGTH (CM) |

FICURE 6. Relationship of ratio of distance from outer annulus to anterior scale margin to distance

from focus to margin (Y/X) to fish length of bluegill with two annuli collected in 1965.

Dashed line separates two age groups and data points within dashed circle represent

bluegill judged most difficult to assign to the proper age group. i

BLUEGILL DELAYED ANNULUS FORMATION 37

Results of this study are in general agreement with the literature regarding the
time of annulus formation of bluegill of various sizes and ages. Younger age
groups invariably formed annuli early in the growing season and there was a
pronounced tendency for smaller members of a given age cohort to show a
relatively high ratio of annual incremental growth to total growth experience.
The test of Frey (1942), designed to compare sizes of carp (Cyprinus carpio)
of a given age with and without current annuli, was applied to the present scale
collection with results similar to those obtained by Gerking (1966) for bluegill;
that segment of an age cohort which had formed current annuli were always of
shorter mean length than their counterparts which had not (Table 3).

TABLE 3. Mean Length of Bluegill of the Same Age Cohort
With and Without Current Annuli.

Mean length (cm)
Collection With current Without current

year Age annuli* annuli*

1965 Ill 16.9 (20) 17.5 (59)

1968 Ill 14.5 (73) 15.5 (42)

1968 IV 15.3 ( 5) 16.8 (36)

• Number in parenthesis indicates sample size.

Gerking (1966) analyzed the growth cycle and potential of bluegill popula-
tions from a number of small lakes in Indiana. In one instance, he regarded the
presence of an unbroken, although highly variable, series of measurements of
the number of circuli between outer annuli and the scale margin (or distance
from annuli to margin) as evidence that an aggregation of bluegill scale samples
belonged to the same age class. This procedure (the generation of a length
frequency of (Y) alone) appears more likely than (Y/X) to detect discontinuity
when plotted against a single axis since (Y) is less influenced by fish length than
(Y/X). In the present case, discontinuity of data points is readily discernible only
when (Y/X) is plotted against fish length because of the angular nature of paths
clear of data points which separate age groups ( Figures 5 and 6) . In general, we
favor the use of (Y/X) rather than (Y) alone because it more fully allows an
interpretation of fish age based on observed relationships of size and age to
annulus formation.

We believe that difficulties associated with the aging of bluegill populations
will be minimized if scale collections are made as late in the growing season as
possible. It is clear that generalizations relating bluegill annulus formation to
latitude should not be made and this view receives a measure of support in the
literature. Age III and IV bluegill from Clearwater Lake, Missouri, for example,
did not complete annulus formation until September (Lane 1954). Similarly,
annulus formation was not completed by early July at Lake Bastrop, Texas ( Serns
and Strawn 1975), even though the population was growing at a rate somewhat
above the national average. At any given latitude, differences in the time of
annulus formation can sometimes result in the incorrect aging of fish with mar-
ginal annuli. Such annuli should not routinely be regarded as new or current
since they may represent an entire season's growth (Hansen 1937, Frey 1942)
(Figure 3).

Effects of fish age on the time of annulus formation among other centrarchid
species appears generally similar to that recorded for bluegill. A tendency for

38 CALIFORNIA FISH AND GAME

young fish to form annuli early in the growing season has been observed for
largemouth bass (Olmstead 1974, Webb and Reeves 1975), smallmouth bass
(Micropterus dolomieui) (Stroud 1948), spotted bass (Micropterus punc-
tulatus) (Webb and Reeves 1975), rock bass (Ambloplites rupestris) (Hile
1941), white crappie (Pomoxis annularis) (Hansen 1937, 1951, Hall, Jenkins,
and Finnell 1954, Morgan 1954), and black crappie (Johnson 1945, Stroud
1948). The consistency of this observation suggests the possibility that the tech-
niques herein described for bluegill may have utility for other warmwater species
as well.

ACKNOWLEDGMENTS
Scale collections from Lake Nacimiento were obtained primarily by seasonal
personnel under the supervision of the junior authors. All figures were drafted
by Nanci Dong. Photographs of bluegill scale impressions were prepared by Jack
Kelley Clark, Cooperative Extension, University of California at Davis. We ex-
tend our thanks to George McCammon, Kenneth Hashagen, Ralph Carpenter,
and Robert Rawstron for their critical reviews of this manuscript.

REFERENCES

Bailey, Merryll M. 1964. Age, growth, maturity, and sex composition of the American smelt, Osmerus mordax
(Mitchill), of Western Lake Superior. Amer. Fish. Soc., Trans., 93(4): 382-395.

Bennett, C. W., D. H. Thompson, and S. A. Parr. 1940. A second year of fisheries investigations at Fork Lake,
1939. III. Nat. Hist. Surv., Biol. Notes., (14): 1-24.

Frey, David C. 1942. Studies on Wisconsin carp. I. Influence of age, size, and sex on time of annulus formation
by 1936 year class. Copeia, 4: 214-223.

Cerking, Shelby D. 1966. Annual growth cycle, growth potential, and growth compensation in the bluegill
sunfish in northern Indiana lakes. Can., Fish. Res. Bd. Jour., 23 (12): 1923-1956.

Hall, Cordon E., Robert M. Jenkins, and Joe C. Finnell. 1954. The influence of environmental conditions upon
the growth of white crappie and black crappie in Oklahoma waters. Ok. Fish. Res. Lab. Rep., (40): 1-56.

Hansen, Donald F. 1937. Date of annual ring formation in the scales of the white crappie. Amer. Fish. Soc.,

Trans., 66: 227-236.

1951. Biology of the white crappie in Illinois. III. Nat. Hist. Surv. Bull., 25 (4): 211-265.

Hile, Ralph. 1941. Age and growth of the rock bass, Ambloplites rupestris (Rafinesque) in Nebish Lake,

Wisconsin. Wise. Acad. Sci., Trans., 33: 189-337.
Hodgson, William C. 1 925. Investigations into the age, length, and maturity of the herring of the southern North

Sea. Part I. Some observations on the scales and growth of the English herring. Minn. Agr. Fish., Fish. Invest.,

Ser. II 7(8): 1-36.

Johnson, Wendell L. 1945. Age and growth of the black and white crappies of Greenwood Lake, Indiana. Ind.
Invest. Lakes, Streams, 2(15): 297-324.

La Faunce, Don A., J. B. Kimsey, and Harold K. Chadwick. 1964. The fishery at Sutherland Reservoir, San Diego

County, California. Calif. Fish Game, 50(4): 271-291.
Lane, Charles E., Jr. 1954. Age and growth of the bluegill, Lepomis m. macrochirus (Rafinesque), in a new

Missouri impoundment. Jour, Wildl. Mgt., 18(3): 358-365.
McFadden, James T 1959. Relationshipof size and age to time of annulus formation in brook trout. Amer. Fish.

Soc, Trans., 88(3): 176-177.

Miller, Edward E. 1 971 . The age and growth of centrarchid fishes in Millerton and Pine Flat reservoirs, California.
Calif. Dept. Fish Game, Inland Fish. Admin. Rep., 71-4, 17 pp.

Morgan, George D. 1 954. Life history of the white crappie ( Pomoxis annularis) of Buckeye Lake, Ohio. Denison
Univ., Sci. Lab. Jour. 43: 113-144.

Olmsted, Larry L. 1974. The ecology of largemouth bass {Micropterus salmoides) and spotted bass [Microp-
terus punctulatus) in Lake Fort Smith, Arkansas. Ph.D. thesis. Univ. Ark. 134 pp.

Proffitt, M. A. 1950. Comparative morphometry and growth of scales in the bluegill, Lepomis m. macrochirus
(Rafinesque), with sf>ecial reference to related body growth. Ph.D. thesis, Univ. Mich., Ann Arbor, Mich. %
PP

Regier, Henry A. 1962. Validation of the scale method for estimating age and growth of bluegills. Amer. Fish.
Soc., Trans., 91(4): 362-374.

BLUECILL DELAYED ANNULUS FORMATION 39

Rothschild, Brian ). 1963 A critique of the scale method for determining the age of the alewife, Alosa pseudoha-
rengus (Wilson). Amer. Fish. Soc., Trans., 92(4): 409-^13.

Serns, Steven L., and Kirk Strawn. 1975. Age and growth of bluegiil, Lepomis macrochirus, in two heated Texas
reservoirs. Amer. Fish. Soc, Trans., 1(34(3): 506-512.

Smith, Stanford H. 1956. Life history of the lake herring of Green Bay, Lake Michigan. U.S. Fish Wildl. Serv.
Bull., 109: 87-138.

Stroud, Richard H. 1948 Growth of the basses and black crappies in Norris Reservoir, Tennessee. Tenn. Acad.
Sci., Jour., 23: 31-99.

Tharratt, Robert C. 1 966 The age and growth of centrarchid fishes in Folsom Lake, California. Calif. Fish Game,
52(1): 4-16

von Geldern, C. E., )r. 1971. Abundance and distribution of fingerling largemouth bass, Micropterus salmoides,
as determined by electrofishing, at Lake Nacimiento, California. Calif. Fish Game, 57(4): 228-245.

von Geldern, C. E., Jr., and Patrick K Tomlmson. 1973. On the analysis of angler catch rate data from warmwa-
ter reservoirs. Calif. Fish Game, 59(4): 281-292.

Webb, Joseph F., and William C. Reeves. 1975. Age and growth of Alabama spotted bass and northern
largemouth bass, p 204-21 5 In Henry Clepper ed. Black bass biology and management. Sfxjrt Fishing Institute,
Wash., DC. 534 p.

APPENDIX 1. Ratio (Y/X) and length of bluegiil with one and three annuli collected in 1%5
and bluegiil with three and four annuli collected in 1%6.

1965 (One annulus present)

Ratio FL (cm) Ratio FL (cm) Ratio FL (cm)

0.59 8.9 0.48 9.1 0.45 9.4

0.49 9.7 0.27 10.0 0.50 10.2

0.51 10.4 0.43 10.7 0.47 10.7

0.37 11.0 0.38 11.0 0.53 11.0

0.41 11.2 0.48 11.2 0.37 12.0

0.31 12.2 0.40 12.2 0.28 12.7

0.38 12.7 0.44 12.7 0.45 12.7

0.49 12.7 0.26 13.0 0.43 13.0

0.45 13.0 0.49 13.0 0.31 13.5

0.38 13.5 0.39 13.5 0.41 13.5

0.37 13.7 0.41 13.7 0.38 14.0

0.40 14.0 0.31 14.7 0.51 15.7

1965 (Three annuli present)

0.13 14.5 0.09 14.7 0.04 16.3

0.06 16.5 0.08 16.5 0.08 16.5

0.10 16.5 0.05 16.8 0.05 16.8

0.07 16.8 0.13 16.8 0.08 17.0

0.04 17.3 0.05 17.5 0.07 17.5

0.18* 17.5 0.04 17.8 0.04 17.8

0.06 17.8 0.05 18.0 0.04 18.3

0.07* 18.5 0.09* 18.8 0.13* 19.6

1966 (Three annuli present)

0.13 13.5 0.06 14.0 0.09 14.0

0.06 14.5 0.08 14.7 0.06 15.2

0.16 15.2 0.05 15.5 0.15 15.7

0.04 16.0 0.04 16.0 0.11 16.0

0.05 16.3 0.05 16.5 0.06 16.5

0.06 16.8 0.07 17.0 0.04 17.3

0.05 17.3 0.04* 18.3 0.05* 18.5

0.05* 18.5 0.06* 18.8 0.09* 18.8

0.04* 19.6 0.10* 20.1

40 CALIFORNIA FISH AND CAME

1966 (Four annuli present)

0.05+ 18.5 0.04+ 19.0 0.04+ 19.6

• Specimens judged not to have formed current annuli.

+ Basis for judging presence or absence of current annuli obscured by small sample size.

APPENDIX 2. Ratio (Y/X) and length of bluegill with one and two annuli collected in 1%7.

1967 (One annulus present)

Ratio FL(cm) Ratio FL(cm) Ratio FL(cm)

0.71 9.7 0.74 9.7 0.79 9.7

0.72 9.9 0.69 10.2 0.73 10.4

0.66 10.7 0.70 10.9 0.68 11.2

0.64 11.2 0.65 11.7

1967 (Two annuli present)

0.58 10.4 0.46 10.7 0.55 10.7

0.63 10.7 0.50 10.9 0.61 10.9

0.67 10.9 0.69 10.9 0.70 10.9

0.59 11.2 0.62 11.2 0.67 11.2

0.52 11.4 0.53 11.4 0.55 11.4

0.57 11.4 0.59 11.4 0.59 11.4

0.61 11.4 0.62 11.4 0.64 11.4

0.66 11.4 0.46 11.7 0.48 11.7

0.55 11.7 0.56 11.7 0.60 11.7

0.62 11.7 0.63 11.7 0.65 11.7

0.49 11.9 0.52 11.9 0.54 11.9

0.56 11.9 0.58 11.9 0.61 11.9

0.64 11.9 0.47 12.2 0.50 12.2

0.50 12.2 0.53 12.2 0.57 12.2

0.57 12.2 0.60 12.2 0.60 12.2

0.46 12.4 0.47 12.4 0.49 12.4

0.60 12.4 0.60 12.4 0.61 12.4

0.63 12.4 0.42 12.7 0.44 12.7

0.46 12.7 0.47 12.7 0.49 12.7

0.50 12.7 0.50 12.7 0.50 12.7

0.54 12.7 0.51 12.7 0.54 12.7

0.59 12 7 0.55 12.7 0.59 12.7

0.61 12.7 0.63 12.7

0.64 12.7 0.22 13.0

0.48 13.0 0.48 13.0

0.49 13.0 0.49 13.0

0.50 13.0 0.53 13.0

0.56 13.0 0.56 13.0

0.63 12.7

0.47 13.0

0.49 13.0

0.50 13.0

0.53 13.0

0-57 13.0 o.eO 13.0 0.61 13.0

0.61 13.0 0.24 13.2 0.30 13.2

0.40 13.2 0.43 13.2 0.47 13.2

BLUECILL DELAYED ANNULUS FORMATION 41

1967 (Two annuli present — continued)

0.50 13.2 0.52 13.2 0.54 13.2

0.54 13.2 0.56 13.2 0.30 13.5

0.31 13.5 0.31 13.5 0.44 13.5

0.45 13.5 0.47 13.5 0.50 13.5

0.50 13.5 0.51 13.5 0.52 13.5

0.59 13.5 0.59 13.5 0.62 13.5

0.29 13.7 0.29 13.7 0.45 13.7

0.46 13.7 0.46 13.7 0.48 13.7

0.49 13.7 0.51 13.7 0.51 13.7

0.51 13.7 0.51 13.7 0.52 13.7

0.53 13.7 0.54 13.7 0.34 14.0

0.35 14.0 0.36 14.0 0.37 14.0

0.39 14.0 0.41 14.0 0.45 14.0

0.50 14.0 0.51 14.0 0.51 14.0

0.52 14.0 0.27 14.2 0.43 14.2

0.43 14.2 0.43 14.2 0.47 14.2

0.48 14.2 0.48 14.2 0.51 14.2

0.55 14.2 0.58 14.2 0.60 14.2

0.60 14.2 0.31 14.5 0.35 14.5

0.40 14.5 0.46 14.5 0.48 14.5

0.50 14.5 0.51 14.5 0.54 14.5

0.56 14.5 0.33 14.7 0.33 14.7

0.34 14.7 0.38 14.7 0.39 14.7

0.40 14.7 0.42 14.7 0.44 14.7

0.46 14.7 0.46 14.7 0.49 14.7

0.50 14.7 0.50 14.7 0.50 14.7

0.51 14.7 0.27 15.0 0.34 15.0

0.37 1 5.0 0.38 1 5.0 0.39 1 5.0

0.42 15.0 0.43 15.0 0.45 15.0

0.46 15.0 0.47 15.0 0.49 15.0

0.49 15.0 0.50 15.0 0.52 15.0

0.54 15.0 0.34 15.2 0.35 15.2

0.36 15.2 0.38 15.2 0.38 15.2

0.39 15.2 0.44 15.2 0.47 15.2

0.49 15.2 0.49 15.2 0.32 15.5

0.34 15.5 0.37 15.5 0.40 15.5

0.41 15.5 0.42 15.5 0.43 15.5

0.43 15.5 0.43 15.5 0.47 15.5

0.51 15.5 0.34 15.8 0.36 15.8

0.39 15.8 0.39 15.8 0.39 15.8

0.39 15.8 0.39 15.8 0.40 15.8

0.40 15.8 0.42 15.8 0.43 15.8

0.44 15.8 0.46 15.8 0.46 15.8

0.56 13.2 0.57 13.2 0.64 13.2

0.47 15.8 0.48 15.8 0.48 15.8

0.28 16.0 0.34 16.0 0.36 16.0

0.37 16.0 0.39 16.0 0.42 16.0

0.43 16.0 0.45 16.0 0.33 16.3

0.41 16.3 0.37 16.5 0.41 16.5

0.27 16.8

42 CALIFORNIA FISH AND CAME

APPENDIX 3. Ratio (Y/X) and length of bluegill with three, four, and five annuli collected
in 1%8.

1968 (Three annuli present)

Ratio
0.05

FL (cm)
10.2

Ratio
0.16

FL (cm)
12.2

Ratio
0.05

FL (cm)
12.4

0.05

12 4

006

12 4

0 08

124

0.19

12 4

0 10

12 7

0 14

127

0.28

12.7

0.07

13.0

0.04

13.2

0.08

13.2

0.18

13.5

0.07

13.7

0.07

13.7

0.08

13.7

0 10

13.7

0.10

13.7

0.11

13.7

0 15

13.7

0.07

14.0

0.08

14.0

0 10

14 0

0.15

14 0

0 16

140

0 18

140

0.08

14.2

0 15

14 2

0 09

14.5

0.13

14.5

0.17

14.5

0.45*

14.5

0.03

14.7

0.04

14.7

0.04

14.7

0.04

14 7

004

147

0 09

147

0.09

14.7

0.09

14 7

0.09

14.7

o.n

14.7

0 15

14.7

0.04

15.0

0.04

15 0

0.07

15.0

0.09

15.0

0.11

15 0

0 13

15 0

0.13

15.0

0.06

15.2

0 08

15.2

0.09

15.2

0.09

15.2

0 13

15.2

0.20*

15.2

0.21*

15.2

0.26*

15.2

0.33*

15.2

0.43*

15.2

0.03

15.5

0.04

15.5

0.05

15.5

0.06

15.5

0.08

15.5

0.09

15.5

0 09

15 5

0 10

15.5

0.17*

0.07

15.7

0.08

15.7

0.09

15 7

0 15*

15 7

0 31*

15.7

0.32*

15.7

0 33*

15.7

0.04

16.0

0.05

16 0

0 20*

16.0

0 25*

16.0

0.03

16 3

0 06

16.3

0.06

16.3

0.08*

16 3

0 26* ....

16 3

0.34*

16.3

0.35*

16 3

004 . ..

16.5

0.10*

16.5

0.30*

16 5

0 04

16.8

0.32*

16.8

0.05*

17 0

0 10*

17 0

0.04*

17.3

0.10* . ..

173

0 14*

173

0 15*

17.3

0.04*

17.8*

0.26*

17.8

0.18*

18.0

0.28*

18.0

0.05*

18.5

0.07*

18.5

0.46*

18.5

0.08*

18.8

0.06*

19.1

0.42*

19.1

1968 (Four
0.35

annuli present)

15.2

0.08

12.7

16.0

0.05

16 3

0 05

165

0.11*

17.6

0.14* .

17 6

0 15*

178

0 06*

18.0

0.09*

18.3

0.04*

18.8

0.05*

19.1

1968 (Five annuli present)
0.07+ 15.2

* Sfjecimens judged not to have formed current annuli.

+ Basis for judging presence or absence of current annuli obscured by small sample size.

Calif. Fish and Came 63 ( 1 ) : 43-5 1 1 977.

STOMACH CONTENTS OF NORTHERN CALIFORNIA
DUNGENESS CRABS, CANCER MAGISTER^

DANIEL W. COTSHALL

Operations Research Branch

California Department of Fish and Came

A total of 208 Dungeness crab, cancer magister, stomachs was examined from
Humboldt Bay and ocean waters west of Eureka, California. The stomachs contained
40 different identifiable food items; clams, fish, isopods, and amphipods were the
most frequently observed animals. Major differences in stomach contents were
evident when crab stomachs from different depths were analyzed.

Northern California crab stomach contents agreed quite closely with those studied
from British Columbia waters.

INTRODUCTION

A study of stomach contents of Dungeness crabs captured in the Humboldt
Bay area from November 1966 through September 1969 was made to determine
the types of food utilized and the relationship between stomach contents and
depth of capture.

METHODS
Crabs were collected by trawling. In Humboldt Bay a 6.1-m (20-ft) skiff was
used to tow a 4.9-m (16-ft) head-rope trawl with 28.7-mm (1% inch) stretch
mesh and 12.7-mm (Vj-inch) stretch mesh liner in the cod-end. Outside Hum-
boldt Bay, both the skiff and the 30-m (100-ft) research vessel, N.B. Scofield,
towing a 12.5-m (41 -ft) head-rope Gulf shrimp trawl (28.7-mm stretch mesh)
were used for collecting in the ocean. Stomachs were removed from crabs and
preserved in 70% isopropyl alcohol. Data recorded for each crab included
carapace width, sex, and location and depth of capture. Stomach contents were
examined with a dissecting microscope. Most of the organisms found in the
stomachs were not identifiable to species, due to the crushing action of the
mandibles and the gastric mill. This action also precluded analysis by volumetric
means. Some animals were identified by distinctive body structures, e.g., fish
otoliths (Figure 1 ), hinges from bivalve shells, pieces of carapace and legs from
crustaceans, polychaete setae, and cephalopod beaks. Whole amphipods and
isopods were sent to appropriate authorities for identification. Common and
scientific names are listed for convenient reference (Table 1 ).

' Accepted for publication March 1976.

CALIFORNIA FISH AND CAME

FIGURE 1 . Otioliths (sagittae) found in Dungeness crab stomachs. A, Northern anchovy, Engraulis
mordax, (right); B, Whitebait smelt, Allosmerus elongatus, (right); C, Night smelt,
Spirinchus starksi, (right); D, Pacific sanddab, Citharichthys sordidus, (left); E, SF>eck-
led sanddab, C. stigmaeus, (right); F, Pacific tomcod, Microgadus proximus, (right).
Photograph by Jack Schott.

DUNGENESS CRAB STOMACH CONTENTS

TABLE 1. List of Common and
Crabs.

Common Name

Hydroids

Polychaete worm

Brittle star
Sand dollar

Dove snail
Moon snail
Nassa mud snail
Snail

Basket cockle

Clams

File yoldia

Lvonsia clam

Macoma clam

Mussel

Nut clam

Razor clam

CephalopKxls

Amphipods

Bay shrimp

Crab

Crustaceans

Cumacean

Cumaceans

Decapods

Euphausid

Isopods

Dungeness crab

Shrimp

Fish

Night smelt
Northern anchovy
Pacific sandab
Pacific tomcod
Smelt

Speckled sandab
Whitebait smelt

E^lgrass

Scientific Names of Organisms Used as Food by Dungeness

Scientific Name

Hydrozoa

Polychaeta

Ophiuroidae
Echinoidea

Mitrella tuberosa
Polinices sp.
Nassarius sp.
GastrofMxla

Clinocardium nuttalli

Pelecypoda

Yoldia lima tula

Lvonsia sp.

Macoma sp.

Mytilus sp.

Nuculana sp.

Siliqua pa tula

Cephalopoda

Amphipoda

Craneon sp.

Bracnyura

Crustacea

Diastylopsis dawsoni

Cumacea

DecafKxla

Euphausiacea

Isopoda

Cancer magister

Natantia

Pisces

Spirinchus starksi
tngraulis mordax
Citharichthys sordidus
Microgadus proximus
Osmeridae

Citharichthys stigmaeus
Allosmerus elongatus
Zostera marina

RESULTS

A total of 208 stomachs was examined; 39 were from crabs collected in
Humboldt Bay and the remainder were from crabs taken from the ocean
between Table Bluff and the mouth of the Mad River. Only 26 stomachs were
empty.

The stomachs contained 40 different identifiable food items (Table 2) repre-
senting six animal phyla and one plant species. Eleven animals were identifiable
to species and eight to genus. Identified species included dove snail, razor clam,
file yoldia, basket cockle, Dungeness crab, night smelt, whitebait smelt, northern
anchovy. Pacific sanddab, speckled sanddab and Pacific tomcod. The animal
phyla represented were Coelenterata (hydroids), Annelida (polychaete
worms), Mollusca (snails, clams, cephalopods), Arthropoda (cumaceans, iso-
pods, amphipods, decapods), Echinodermata (sand dollars, brittle stars), and
Chordata (fishes). Plant material consisted of eelgrass fragments. The five most
frequently observed categories were: unidentified clams — 34.6%; unidentified
fish — 24.0%; isopods — 1 7.3%; amphipods — 1 6.3%; and razor clams — 1 1 .5%. U
is interesting to note that isopods were the most frequently encountered animals
in stomachs collected during November and December 1966, but those collect-
ed from approximately the same location in August and September 1969, did not
contain one identifiable isopod.

CALIFORNIA FISH AND CAME

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I

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m — •— —

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CALIFORNIA FISH AND CAME

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FIGURE 2. Frequency of occurrence of nine food categories found in Dungeness crab stomachs
collected from 0 to 89 m (49 fm) grouped by 18-m (10-fm) intervals.

50 CALIFORNIA FISH AND CAME

Generally, clams, crustaceans, and fish were the three most important food
items. Fishes were dominant in stomachs examined from Humboldt Bay in 1967.
Crustaceans were the most frequently occurring animals in crab stomachs col-
lected outside the bay in 1969 (Table 3).

Major differences in stomach contents were noted when comparisons of
crabs caught from 1 8-m ( 1 0-fm ) depth intervals were made ( Figure 2 ) . Contents
from the 208 stomachs were placed into nine categories. The percent frequency
of occurrence of amphipods and fish decreased with increasing depth, while
polychaetes, snails, clams, cumaceans, isopods and echinoderms increased in
frequency.

DISCUSSION

Butler (1954) examined 170 Dungeness crab stomachs collected in the vicin-
ity of the Queen Charlotte Islands, British Columbia. He found crustaceans were
the most frequently occurring food item, followed by clams, with only four
stomachs containing fish remains. In his study there was a large difference
between stomach contents of small and large crabs, but very little difference in
stomach contents between sexes. In Butler's study small crabs (less than 1(X)
mm) fed mostly on small crustaceans, the larger crabs (166 mm or larger) fed
primarily on clams. Clams, followed by crustaceans, were the most frequently
observed animals in intermediate-size crabs (101 to 165 mm) from British
Columbia. Conversely, fish, crustaceans, and clams were of almost equal impor-
tance in northern California for intermediate-size crabs (101 to 150 mm). In my
study fish were the most frequently observed organism in stomachs from small
crabs (less than 100 mm) while clams were more frequently observed in large
crabs ( 1 51 mm and larger) . Finally, he observed a high frequency of Dungeness
crab remains in stomachs collected during August.

The results of the two studies are similar in that both showed clams as
important food items. Differences in the studies occurred in order of importance
of major food organisms. In the California study, clams and crustaceans were
the most frequently observed faunal categories, respectively; in the stomachs
examined from Canada, crustaceans were the most frequently observed food
followed by clams. Northern California crabs were also cannibalistic, having
eaten very small incoming year-class crabs in late summer (Table 2), but to a
lesser degree than Queen Charlotte Island crabs. The most obvious difference
in the two studies is the almost total absence of fish in Queen Charlotte Island
crab stomachs, and the high incidence of fish remains in northern California crab
stomachs. Most of the fish remains came from crabs collected in less than 18
m ( 1 0 fm ) . The otoliths examined were primarily from fish less than 1 -year old.
Evidently crabs are capable of capturing juvenile fishes and possibly some adults
that come within their range. It may be that the shallow waters tend to be more
murky making it easy for crabs to capture fish.

Butler describes crab feeding behavior as probing in the substrate with claws
until contact with a food object is made, then the claws close. The large number
of infaunal (animals living in the substrate) organisms that were found in both
studies substantiates this observed feeding behavior. I have observed crabs
"digging" basket cockles in southeastern Alaskan waters; some of the crabs had
excavated cavities approximately 0.3-m (1-ft) deep. A few of the crabs in these

DUNCENESS CRAB STOMACH CONTENTS 51

excavations were clutching large cockles. The high frequency of sand in north-
ern California crab stomachs probably resulted from this type of feeding (Table
2).

From my study in northern California and from Butler's work, it appears that
Dungeness crabs are opportunistic feeders, utilizing organisms encountered on
or near the surface of the substrate (fish, crustaceans, brittle stars) as well as
buried clams and worms.

Because of the wide diversity of food items found in the stomachs, it does not
seem likely that presence or absence of a particular benthic animal would be
a major limiting factor on the present crab population.

ACKNOWLEDGMENTS

This study could not have been completed without the assistance and sugges-
tions of the following: John Span and Paul Dinnel assisted in collection of the
crabs and preliminary sorting of stomach contents; John Fitch identified otoliths;
Jarl-Ove Stranberg identified isopods; J. L. Barnard identified amphipods; and the
figure was illustrated by Cathy Short. My sincere thanks to all for their contribu-
tions.

REFERENCES

Butler, T. H 1954 Food of the commercial crab in the Queen Charlotte Islands Region. Canada, Fish. Res. Bd ,
Pac. Prog. Rept No. 99: 3-5.

Calif Fish and Came 63 ( 1 ) ; 52-57. 1 977

REACTIONS OF FISH RED BLOOD CELLS WITH
MUCUS AND SERA FROM OTHER FISH(ES) ^

ALBERT C. SMITH

Department of Pathology

John A. Burns School of Medicine

University of Hawaii

1960 East- West Road

Honolulu, Hawaii 96822

The possibility was tested that an incompatibility among fishes may be based on
skin mucus from some individuals reacting, probably immunologically, with red
blood cells from other individuals.

A preliminary study demonstrated that mucus from mullet, Mugil cephalus,
clumped red cells from one of several tilapia, Tilapia mossambica. However, tilapia
mucus had little, if any, effect on the tilapia red cells. A more extensive study was
then carried out with red cells from the milkfish, Chanos chanos, tested against
mucus and sera from the same milkfish, snapper, Lutianus fulvus, and tilapia. No
reactions of cells occurred in milkfish mucus or any serum, but there were moderate
to strong reactions in the mucus of many snapper and a few tilapia.

Research in progress is attempting to determine the frequency of mucus and red
cell incompatibility reactions among and between other species; if there is an in vivo
correlation of these in c/Vz-o findings, especially what the disease consequences (and,
therefore, the significance to aquaculture) might be; and the value of a possible
preventive measure.

INTRODUCTION

Individuals of the same or different fish species are known to produce incom-
patibility reactions among members of the same group or between groups. These
are frequently behavioral, e.g., when individuals contest for dominance over
territory, but can also be chemical. In the latter case, chemicals may manifest
themselves by preventing spawning or hatching of eggs, slowing growth, increas-
ing mortality, or decreasing heart rate (Francis, et al. 1974).

The possibility of an immunologic type of chemical incompatibility existing
among fishes does not seem to have been explored. However, such an incom-
patibility is suggested by relatively recent reports of fish skin mucus containing
antibodies with some degree of specificity against mammalian red blood cells
(Di Conza 1970; Bradshaw, et al. 1971 ), or containing high molecular weight
immunoglobulins (Di Conza and Halliday 1971; Fletcher and White 1973),
including IgM (Bradshaw, et al. 1971 ), which commonly react immunologically
with red cells. Absorption of such antibodies into the blood of susceptible fishes
could theoretically cause a clumping of red cells with subsequent hemolysis and
anemia. This might be expected in only a certain percentage of individuals in
any one tank; and might explain the familiar observation, at least in some cases,
of only certain fishes "going downhill." Such debilitated animals might also be
expected to be the first to develop disease which, once established, may then
spread to other members of the tank population.

My research explored the possibility that skin mucus from certain individual
fishes may react with red cells from other individuals, both of the same and of
different species. In a preliminary study, mucus from the mullet, Mugil cephalus,

' Oceanic Institute Contribution No. 122. Accepted for Publication March 1976.

REACTIONS FISH BLOOD CELLS WITH MUCUS 53

and tilapia, Tilapia mossambica, was tested against red cells from the latter
species. These species were used because of availability, and because of the
chance observation of an anemia in one tilapia that possibly was the result of
an incompatibility reaction of its red cells with mucus from other tilapia or mullet
that had been in the same tank. In a second study, both mucus and sera from
the milkfish, Chanos chanos, snapper, Lutianus fulvus, and another sample of
tilapia were tested against red cells from the milkfish. This study extends the
number of species tested for mucus and red cell reactions, and might indicate
if there is any relationship between mucus and serum effects on red cells.

MATERIALS AND METHODS
Obtaining Mucus

Mucus from a mullet selected at random was collected by first lightly blotting
the fish with a paper towel to remove excess water, followed by gently rubbing
it from head to tail with the fingers. This action seemed to stimulate secretion
of mucus, as well as to cause it to collect in front of the moving hand. Mucus
from the milkfish, snapper, and tilapia was collected easily by letting the animals
thrash a few minutes in a net out of the water. The mucus accumulated as a froth
over the body, from which it was readily removed by the rubbing action just
described. Each fish was placed back in the net several times so that it could
continue to thrash and additional amounts of mucus could be collected. The
mucus was placed directly into a vial and centrifuged at 2,200 X g for 10 min
at 25 C (77 F). The clear supernatant was then stored frozen until ready for
testing with red cells.

Obtaining Sera and Red Cells

Milkfish, snapper, and tilapia were bled by first blotting, as explained for the
mullet, to remove excess water, and then severing the caudal peduncle with a
knife. The blood was allowed to flow alternately into two vials, one empty and
the other containing EDTA (anticoagulant).

Blood collected in the first vial was allowed to clot in the refrigerator. After
1 to 2 hr, the clot was freed from the edges of the vial by "rimming" with an
applicator stick. The next day, the clear serum was withdrawn by pipette from
the clot and either used immediately or stored frozen until ready for testing
against red cells.

The anticoagulated blood in the second vial was diluted with saline (0.85 g
% NaCI ) solution so that the final volume of fluid to settled ( uncentrifuged ) cells
was approximately 5:1. This cellular suspension was then used, either the same
day or after a maximum of one night's storage in the refrigerator, in the tests with
mucus and sera.

Testing Mucus and Sera against Red Cells
One drop of mucus or serum was mixed with one drop of red cell suspension
on a microscope slide. Controls were one drop of saline solution mixed with one
drop of the suspension. These mixtures were allowed to incubate under a Petri
dish cover at 25 C ( 77 F ) for up to 3 or 4 minutes before being read, as described
below. Strong reactions, however, were noticeable within a few seconds.

54 CALIFORNIA FISH AND CAME

Test I

Mucus from one mullet and five tilapia were individually tested against red
cells from each tilapia. Controls were saline solution and tilapia red cells.

Test II
Mucus and sera from the same 10 milkfish, four snapper, and six tilapia were
individually tested against red cells from each of the milkfish. Controls were
saline solution and milkfish red cells.

Key to Rating of Reactions

A scale of 0 to 4+ was followed:

0 = No reaction; cells dispersed.

1+ = Slight clumping, but most cells dispersed.

2+ = Slightly larger clumps; interspersed fine strands.

3+ = Several large clumps; increased number and thickness of strands; loose
network; slightly hazy background.

4+ = Usually one, sometimes a few, large clumps in tight network; well-
developed strands in reticular formation; clear background.

RESULTS

The first test (Table 1 ) demonstrated a moderately strong (2+ ) reaction of
at least one tilapia's red cells in mullet mucus. The other reactions were equivo-
cal (0-1 + ), and one was clearly negative (0) . Mixing of tilapia mucus and red
cells also gave negative results, except for one case where the results appeared
equivocal.

TABLE 1. Reactions of Tilapia Red Cells with Mucus (Test I)

Red cells

Mucus

Saline

Tilapia

Mullet

1-3

Tilapia
4

(control)

2 +

0-1 +

0-1-1-

Note: 0, no reaction, cells dispersed; 1 +, slight clumping, but most cells dispersed; 2 + , slightly larger clumps,
interspersed fine strands.

In the second test (Table 2), none of the milkfish mucus or any sera reacted
with the red cells of this species. However, the mucus from three of the four
snapper and from two of the six tilapia reacted moderately to strongly with red
cells from a number of milkfish. Only one fish, a tilapia ( #5), produced mucus
which reacted with the red cells from all 10 milkfish.

REACTIONS FISH BLOOD CELLS WITH MUCUS 55

TABLE 2. Reactions of Milkfish Red Cells with Mucus and Sera (Test II)

Sera

Mucus

Milkfish,
snapper.

Red Cells

Milkfish

Snapper

Tilap

Saline

Milkfish

1-10

;

1-3

and tilapia

(control)

1 +

3 +

4 +

3 +

4 +

1 +

3 +

4 +

3 +

4 +

?1 +

1 +

3 +

4 +

3 +

4 +

2 +

4 +

3 +

4 +

?1 +

4 +

Note: 0, no reaction, cells dispersed; 1 +, slight clumping, but most cells dispersed; 2 + , slightly larger clumps,
interspersed fine strands; 3 + , several large clumps, increased number and thickness of strands, loose network,
slightly hazy background; 4 + , usually one, sometimes a few, large clumps in tight network; well-developed strands
in reticular formation; clear background.

Dried preparations of the reactions of mucus with red cells ( Figure 1 ) clearly
show details as described in the key. Negative reactions, in addition, show
crystalline patterns which are an effect of drying.

DISCUSSION AND CONCLUSIONS

That the reactions of red cells with mucus may have an immunologic basis
is suggested by: (i) the variable distribution of individuals among the same
species that show reactions and their crossing of taxonomic lines, remindful of
blood group systems; and (ii) the known fact, as mentioned in the introduction,
that antibodies against mammalian red cells, or immunoglobulins that could
have an anlibody function against red cells, exist in fish mucus.

The finding of no reaction of red cells with any sera, even from individuals
whose mucus was active against red cells, suggests production of the reacting
substances locally in the skin rather than being a product from serum. This view
is consistent with that of Di Conza and Halliday (1971 ), who based their view
on findings in the catfish, Tachysurus australis, of skin lymphoid cells which
could be involved in local antibody synthesis, and of differences in hemaggluti-
nins and other immunoglobulins between skin mucus and sera.

My study indicates the basis for a possible immunologic type of incompatibili-
ty among certain individual fishes within a given tank population, and further
studies are in progress that may elucidate additional aspects of the problem.
Specifically, these studies are attempting to determine how widespread are in
vitro incompatibility reactions of mucus and red cells among and between
various species. This effort is being conducted by testing a greater number of
individuals of a given species, as well as more species. The studies also are
attempting to determine if this type of incompatibility is the cause of in vivo
debility and eventually disease in certain fishes within the same tank. Evidence
is being obtained indirectly by testing debilitated fishes to determine if their red
cells are in low number (anemia), and if they will react with mucus of other
individuals present. Removal of the latter may then lead to an improvement in
the health of the former. A second approach is adding mucus directly to tank

CALIFORNIA FISH AND CAME

%^'4

FIGURE 1. Reactions of mucus with red cells. A, 4+ reaction: nnucus from snapper #3 with red
cells from milkfish #9. B, two negative (0) reactions: mucus from snapper #2 with
red cells from milkfish #8 and #9, reading left to right.

REACTIONS FISH BLOOD CELLS WITH MUCUS 57

populations and watching for signs of failing health in some fishes. These are then
bled and their red cells tested for signs of reaction with mucus that had been
added. Finally, the studies hope to develop a method to prevent possible debility
from reactions of mucus with red cells. One simple method under investigation
is rearing fishes through their earliest stages in water which also circulates among
adults. This arrangement exposes developing fishes to a variety of foreign sub-
stances, including mucus, so that they may be accepted as part of "self" by the
maturing immune mechanism. Thus, these substances may not produce reac-
tions, based on sensitization, should later contact be made with them.

ACKNOWLEDGMENTS

I thank Janice Haraguchi, Oceanic Institute, Waimanalo, Hawaii, for superior
technical assistance in the laboratory; and Deborah J. Smith, President, Hawaii
BioMarine, Honolulu, Hawaii, and H. Burr Steinbach, President, Oceanic Insti-
tute, for critical reading of the manuscript. This research was supported through
a consulting contract from the Oceanic Institute, under a grant (#AID/TA-C-
1 1 89, on "Research in artificial propagation of milkfish" ) from the United States
Agency for International Development.

NOTE

Since submission of the manuscript, the following article appeared with infor-
mation that is consistent with the view of mucus antibodies being produced
locally in the skin rather than being derived from serum: Mawdesley-Thomas,
L. E. 1975. Some diseases of muscle: 343-363. /nlhe pathology of fishes (Edited
by Ribelin, W. E., and Migaki, C). The University of Wisconsin Press, Madison.
1004 p.

REFERENCES

Bradshaw, C. M., A. S. Richard, and M. M. Sigel. 1971. IgM antibodies in fish mucus. Soc. Exp. Biol. Med., Proc.,
136: 1122-1124.

Di Conza, ). ). 1970. Some characteristics of natural haemagglutinins found in serum and mucus of the catfish,
Tachysurus australis. Aust. J. Exp. Biol. Med. Sci., 48:515-523.

, and W. ). Halliday. 1971. Relationship of catfish serum antibodies to immunoglobulin in mucus

secretions. Aust. ). Exp. Biol. Med. Sci., 49: 517-519.

Fletcher, T. C, and A. White. 1973. Antibody production in the plaice { Pleuronectes platessa L.) after oral and
parenteral immunization with Vibrio angui//arum anugens. Aquaculture, 1: 417-428.

Francis, A. A., F. Smith, and P. Pfuderer. 1974. A heart-rate bioassay for crowding factors in goldfish. Prog.
Fish-Cult., 36: 196-200.

Kearn, C. C. 1974. The effects of fish skin mucus on hatching in the monogenean parasite Entobdella soleae
from the mouth of the common sole, Solea solea. Parasitology, 68: 173-188.

NOTES

EXTENSION OF RED FOX DISTRIBUTION
IN CALIFORNIA

The red fox (Vulpes fulva) is widespread throughout North America. Hall and
Kelson (1959) recognized 12 subspecies of red fox.

In California the Sierra Nevada red fox (Vulpes fulva necator) inhabits the
high Sierra Nevada and Cascade mountains. It is found chiefly above 2,135 m
(7,000 ft) in elevation, seldom venturing below 1,525 m (5,000 ft). The present
distribution of the Sierra Nevada red fox extends from near Medicine Lake,
Siskiyou County south to possibly Siretta Peak, Tulare County (Schempf and
White 1975).

The Central Valley of California has a population of red fox of unknown
taxonomic status. This valley population was first noted in the latter part of the
19th century near the Sutter Buttes. Ingles (1965) and Grinnell, Dixon and
Linsdale (1937) have suggested that the valley red fox was introduced by man.
Its distribution in 1937 included Colusa, Glenn, Tehama, Sutter and Butte coun-
ties.

As part of a study concerning carnivores in California the University of Califor-
nia, Berkeley and the California Department of Fish and Game have collected
sightings of red fox in California from biologists, game wardens and trappers
(Schempf and White 1975).

The valley population of red fox is increasing and extending its distribution
north, south and west. Recent observations indicate that the major concentra-
tions of red fox in the Central Valley are found adjacent to the Sacramento River
near Red Bluff south to the Butte Sink area, Colusa County.

However, the valley red fox has been observed in Shasta, Trinity, Tehama,
Butte, Colusa, Glenn, Sutter, Yuba, Yolo, Napa, Solano, El Dorado and San
Joaquin counties (Gray 1975). Isolated observations have been made in Marin
and Mendocino counties (Schempf and White 1975) which are near the coast.

ACKNOWLEDGMENTS

This study was supported by Federal Aid in Wildlife Restoration Project W-54-
R, "Nongame Wildlife Investigations," under the supervision of Howard Leach,
California Department of Fish and Game.

Literature Cited

Cray, R. L. 1975. Sacramento Valley red fox survey. Calif. Dept. Fish and Came, )ob 11-1.2, Progress report.
Unpublished.

Grinnell, )., |. Dixon and ). M. Linsdale. 1937. Furbearing mammals of California. Vol. 2, Univ. Calif. Press,
Berkeley, 402 p.

Hall, R E. and K. R. Kelson. 1959. The mammals of North America. Vol. 2, The Ronald Press, New York, 536

P
Ingles, L. G. 1965 Mammals of the Pacific States. Stanford Univ. Press, Palo Alto, 506 p.
Schempf, P. F. and M. White. 1975. Occurrence of six furbearer populations in U.S. National Forest lands of

Northern California Preliminary Report for U.S. Forest Service, Unpublished.

Randall L. Gray, 4260 Silver Crest Avenue, Sacramento, Ca. 95821
Submitted for publication April 1976.

NOTES 59

ACORN SELECTION BY BAND-TAILED PIGEONS

In 1975, at the University of California's Hopland Field Station, Mendocino
County, California, a heavy crop of blue oak (Quercus douglasii) acorns attract-
ed a large population of migratory band-tailed pigeons (Columbia fasciata). In
October, 1975, data on feeding behavior of the band-tailed pigeons was collect-
ed.

Blue oak woodland is the major plant community in the study area. Average
tree density was estimated by Murphy and Crampton (1964) at 494 to 618 trees
per ha (200 to 250 trees per acre). Similar findings were reported by White
(1966) for oak woodlands in central coastal California. The woodland understo-
ry is composed largely of annual grass species {Avena sp., Bromus sp. and
others).

During the hunting season (October 4 through October 19) 29 pigeons were
collected and their crop and stomach contents examined. Crop and stomach
contents contained only sound acorns of blue oak. Each whole acorn was
measured (length and width) and weighed. A random sample of acorns from
known pigeon feeding areas was collected and used to characterize and com-
pare the physiognomy of acorns consumed by pigeons and that of all available
blue oak acorns. The 't' test for unequal sample sizes (Steel and Torrie 1960)
was used to compare the two samples (Tables 1 and 2).

The data from Table 1 indicate that acorns collected from the crops and
stomachs of pigeons and those collected at random represented two distinct
groups based upon physiognomic characteristics. Furthermore, acorns selected
by pigeons were significantly smaller ( p < .01 ) . The greatest differences between
samples were observed in width and weight of acorns. When the data were
separated into 5 day collection intervals (Table 2) the differences between
width and weight remained significant throughout the study period. However,
differences in acorn length became progressively less significant.

TABLE 1. Comparisons of Average Sizes of Randomly Collected Blue Oak Acorns and
Acorns Collected from Band-tailed Pigeon Crops.

Sample

Crop

Random

't' value

• Significant at the 1% level.

TABLE 2. Average Sizes of Blue Oak Acorns Collected at Five Day Intervals from the Crops
of Band-tailed Pigeons.

< No. No. Length Width Weight

Date pigeons acorns (cm) (cm) (g)

10/4-8/1975 4 16 2.53t 1.31t 2.79t

10/9-13/1975 11 30 2.65* 1.32t 3.06t

10/14-18/1975 14 77 2.73ns 1.27t 2.98t

•, t Differences between average sizes of the random collection (Table 1 ) and crop acorns collected during each
interval are significantly different at the 5% and 1% levels, respectively, using the 't' test for unequal sample
sizes.
. ns Not significant at the 5% level.

In 1975 average blue oak acorn production per tree on the study area was 2.3
times as heavy as interior live oak (Q. wislizenii) and 5.3 times as heavy as black

ength
(cm)

Width

(cm)

Weigh
(g)

2.68

1.29

2.98

2.77

1.72

5.07

2.98*

19.79*

15.20

60 CALIFORNIA FISH AND CAME

oak (Q. kelloggii), the second and third most abundant oak species in the area
respectively (Fry, unpublished data). This fact may be responsible for the pi-
geons' exclusive use of blue oak acorns. Smith (1968) stated that band-tailed
pigeons usually fed on one abundant food item even though other foods were
available. Similar findings were reported by Murton (1971) for the European
wood pigeon (C. palumbus).

Gibb (1970) found that the New Zealand pigeon (Hemiphaga novaeseelan-
diae), feeding on cultured plums, rejected fruits larger than 24 mm in diameter.
In the present study the band-tailed pigeon was shown to exhibit size-specific
selectivity while feeding on acorns. Selectivity in feeding can be the result of
structural or functional limitations (Welty 1964). How this may relate to the
feeding strategy of the band-tailed pigeon is not known at this time.

ACKNOWLEDGMENTS
We wish to thank Brown San Diego for his help in collecting specimens for
analysis and Dr. Marshall White, Department of Wildlife and Fisheries, Univer-
sity of California, Berkeley, for reviewing the manuscript.

REFERENCES

Gibb, ) A. 1970. A pigeon's choice of plums. Notornis 17(3): 239.

Murphy, A. H. and 8. Crampton. 1964. Quality and yield of forage as affected by chemical removal of blue

oak (Quercus douglaslij. ). Range Manage., 17(3): 142-144.
Murton, R. K. 1971. The significance of a specific search image in the feeding behavior of the wood pigeon.

Behavior, 49(1-2): 10--42.

Smith, W. A. 1968. The band-tailed pigeon in California. Calif. Fish Came, 54(1): 4-16.
Steel, R. G. D. and ). H. Torrie. 1960. Principles and procedures of statistics. McGraw-Hill Book Co. In p. 67-75.
Welty, ). C. 1964. Food and digestion, p. 94-95 in ). C. Welty, The Life of Birds, second edition. W. B. Saunders
Co., Philadelphia.

White, K. L. 1966. Structure and composition of foothill woodland in central coastal California. Ecology, 47(2):
229-237.

Michael £ Fry, Range Management, University of California, Berkeley, CA.
94720 and Charles £ Vaughn, Agronomy and Range Science, University of
California, Davis, CA. 95616. Accepted June 1976.

ALABAMA SPOTTED BASS GROW AT RECORD
RATE IN LAKE PERRIS, CALIFORNIA

On April 6, 1973, the California Fish and Game Commission authorized the
introduction of Alabama spotted bass (Micropterus punctulatus henshalli) as
part of California's experimental management program for reservoir fisheries
enhancement. A previous introduction of northern spotted bass (M. p. punc-
tulatus) from Ohio in 1933 was successful to the extent that established popula-
tions developed in the Cosumnes River, El Dorado County, and the Feather
River, Sutter County (McKechnie 1966). The genetic purity of these stocks is
questionable, however, and it is believed that hybridization with previously
established smallmouth bass (Micropterus dolomieui) populations may have
occurred. Brood stocks of spotted bass were not maintained within California's
hatchery system and a reintroduction of the species was, therefore, authorized.!

The decision to introduce Alabama spotted bass (as opposed to a reintroduc-
tion of the northern form) was based largely on the rapid growth and longevity]
they achieve in certain oligotrophic impoundments in Alabama (Gilbert 1973).
Lewis Smith Lake, Cullman, Walker, and Winston counties, for example, regular-

NOTES 61

ly produces spotted bass in excess of 2.3 kg (5 lb) and a number of Age VI, VII,
and VIII specimens have been identified (Webb and Reeves 1975). Because of
the possibility that genetic factors may be partially responsible for the rapid
growth of spotted bass in Lewis Smith Lake (Samuel L. Spencer, Ala. Dept. Cons,
and Nat. Res., pers. comm.), it was decided to obtain fish from this source for
importation to California.

Personnel from the Alabama Department of Conservation and Natural Re-
sources collected approximately 130 adult spotted bass from Lewis Smith Lake
in the winter of 1973-74. These specimens were then flown to Ontario, Califor-
nia by California Department of Fish and Game pilots Carrol Faist and Pat Simon
on January 25, 1974. Following inspection for diseases and parasites and the
removal of the left ventral fin, 94 individuals ranging from approximately 25 cm
(10 inches) to 0.9 kg (2 lb) were released in Lake Perris, Riverside County.
Remaining specimens, aside from six individuals which were preserved in forma-
lin, were then transferred to Central Valleys Hatchery (Sacramento County).

Lake Perris, the southern terminal reservoir for the California State Water
Project, is an 809-ha (2000-acre) impoundment located about 48 km (30 miles)
southeast of San Bernardino. Dam construction was essentially complete in 1973
and initial water storage began in that year. The reservoir has the high basic
fertility associated with California impoundments south of the Tehachapi Moun-
tains. At present. Lake Perris contains significant populations of Alabama spotted
bass, channel catfish (Ictalurus punctatus), green sunfish {Lepomis cyanellus),
and rainbow trout {Salmo gairdneri).

Reproduction of spotted bass in Lake Perris was first confirmed in July 1974,
when a number of fingerlings were collected with electrofishing gear. Subse-
quent observations with SCUBA equipment in the fall of 1974 again revealed the
presence of numbers of Age 0 spotted bass which appeared to average about
15 cm (6 inches) in length. Continued sampling through 1975 failed to confirm
successful spawning in that year although the presence of a small number of 20
to 23-cm (8 to 9-inch) specimens in early 1976 appeared to indicate that some
reproduction had occurred.

Creel checks at Lake Perris in 1974 and 1975 recorded only an occasional
spotted bass in the sport catch. On January 3 and 10, 1976, however, angling
companions David W. Nollar and Daniel Leader reported an aggregate (or
combined) catch of approximately 50 spotted bass over the 2-day period. Fish
caught ranged from an estimated 0.7 kg (1.5 lb) to 2.6 kg (5.7 lb). The weight
of the largest specimen was later confirmed by the first junior author who judged
the fish to be approximately 46 cm (18 inches) in length. Leader, who caught
the largest fish on January 3, also took a five-fish limit on January 10 which
weighed over 7.7 kg (17 lb).

Scale samples were taken from the largest specimen (which was being mount-
ed by a taxidermist) at a point near the tip of the left pectoral fin for an analysis
of age and growth characteristics. The sample was cleaned and mounted on a
cellulose acetate strip and examined with the aid of an Eberbach scale projector
with a magnification of 42x.

CALIFORNIA FISH AND CAME

■'^

FICURE 1 . Photograph of scale from 2.6 kg Alabama spotted bass taken from Lake Perris on January
3, 1976. Arrows depict annuli. The inner annulus is considered questionable because
of the lack of cutting over in the lateral field. Photograph by Jack Kelley Clark, Coopera-
tive Extension, Liniversity of California at Davis.

Examination of the scale sample revealed the presence of a single well defined
annulus near the margin (Figure 1 ). There appeared to be some possibility that
a centrally located (although poorly defined) annulus was also present. In our
judgment, the central annulus (if valid) was laid down in 1975 while the outer
annulus represents the 1976 mark. Conversely, if the central mark is not a true
annulus, the outer annulus would be presumed to have been laid down in 1975.
In either event, we judge this specimen to be a member of the 1974 year class
(as opposed to an originally stocked specimen) and this view is supported by
the following evidence: (1 ) the fish was unmarked (all fish originally stocked
were marked by removal of the left ventral fin); (2) spotted bass from Lewis
Smith Lake form easily recognizable annuli (Webb and Reeves 1975) and ex-
amination of representative scale samples from the original stock prior to their
introduction most often showed two well defined annuli ( Figure 2); and (3) the
present abundance of large spotted bass in Lake Perris lends credence to the
notion that the 1974 year class grew at an exceptionally rapid rate.

NOTES

»«W

FIGURE 2. Photograph of scale from 30.5 cm Alabama spotted bass taken from Lewis Smith Lake,
Alabama, in January 1 974. Arrows depict annuli. Scale configuration was representative
of specimens originally introduced into Lake Perris. Photograph by Jack Kelley Clark,
Cooperative Extension, University of California at Davis.

To the best of our knowledge, the growth achieved by this individual consti-
tutes a record for the species over a 2-year interval. At Lewis Smith Lake, the
most rapidly growing specinnens do not reach 45.7 cm (18 inches) until near the
«nd of their fourth growing season (Webb and Reeves 1975). The most rapid
early growth previously recorded occurred at Granada Reservoir, Mississippi,
where spotted bass reached a mean length of 27.9 cm (11 inches) at Age II
(Towery 1964).

REFERENCES

Gilbert, R. ). 1973. Systematics of MIcropterus p. punctulatus and M. p. henshalll, and the life history of M. p.

henshalli. Ph.D. thesis. Auburn Univ. 146 p.
•McKechnie, R. ). 1966. Spotted bass. Pages 366-370 //? A. Calhoun, ed. Inland fisheries management. Calif. Dept.

Fish Came. 546 p.
Towery, B. A. 1964. Fisheries investigation on flood control reservoirs. Prog. Rept. F-6-R (Job III — age and

growth studies) Mississippi Game Fish. 21 p.
Webb, Joseph F., and William C. Reeves. 1975. Age and growth of Alabama spotted bass and northern

largemouth bass. Pages 204-215 in Henry Clepper, ed. Black bass biology and management. Sport Fishing

Institute, Wash., D. C. 534 p.

64 CALIFORNIA FISH AND CAME ^

Delores Brown, Kenneth D. Aasen, and C. £ von Celdern, jr., Inland Fisheries
Branch, California Department of Fish and Came. Portions of this work were
performed as part of Dingell-Johnson Project California F- 18-R, "Experimental '
Reservoir Management", supported by Federal Aid to Fish Restoration funds.
Accepted April 1976.

BIRTH OF A CALIFORNIA SEA LION,
ON SOUTHEAST FARALLON ISLAND

The California sea lion, Zaiophus californianus (Gill), is distributed along most *
of the western coast of North America, occurring from British Columbia in the
north (Hancock 1970), south to the tip of Baja California and throughout the>
Gulf of California (King 1964). North of the central California coast, however,^
the population is thought to be composed entirely of males, and the northern-
most breeding colony is located at Point Piedras Blancas, San Luis Obispo '
County ( Lat 35° 40' N ) ( Peterson 1 968) . Thus, we consider it to be an event of .
no small significance that we observed the presence of a pregnant female
California sea lion on Southeast Farallon Island ( Lat 3r 45' N ) in June 1 974, and
subsequently in July 1974 the presence of a female with a newly born pup was ^
noted.

The initial observations were made at approximately 2000 hours on 12 June ^
1974, when Raymond J. Pierotti and T. James Lewis observed a small California
sea lion being actively pursued by a large adult male of the same species. ^
Subsequent observation through binoculars revealed that the smaller individual
was a female with a visibly distended abdomen that dragged across the rocks
as she moved. The male appeared to be attempting to sniff the ano-genital region ^
of the female, a pattern generally associated with pre-copulatory behavior in this ^
species (Peterson and Bartholomew 1967). \

In late June, David G. Ainley observed a newborn sea lion pup on the island, ,
but because Steller sea lions, Eumetopias jubatus (Schreber), breed annually on ■•
the Farallones, it was assumed that the pup was a stray of this species. However, i
on 1 0 July, Malcolm Coulter and Pierotti were observing the behavior of Western '
gulls, Larus occidentalis (Audubon), from a blind high above the water wher
we noticed an unusually small sea lion with a pup on some rocks adjoining the '
water. It was our opinion that the female sea lion with the pup was a California
sea lion, but at the time we were too far away to confirm our initial impression. ^
We proceeded to maneuver more closely to the sea lions, collecting three more
witnesses ( Lewis, James Higbee, and Roger Stoll ) in the process. Eventually, two i
of us were able to approach to within 10 m (33 ft) of the pair and take a series J
of photographs (Figures 1 and 2). The female became agitated by our presence
and rose up and emitted the characteristic Zaiophus "bark". Subsequently, the ^
pair was also observed by Ainley and by Robert Boekelheide, another employee j
of the Point Reyes Bird Observatory. ^

These observations are of significance not only because the breeding distribu- '

tion of the California sea lion is extended by about 300 km (180 miles), but it ^
is also the most northerly record of a live female Zaiophus (Bruce Mate pers.

commun. ) . We are hopeful that this mother and pup may be the advance guard '
of a future breeding colony of Zaiophus on the Farallones. Particularly, because

it was in a very similar manner that the Northern elephant seal, Mirounga \

angustirostris ( Lesson), began its recolonization of the Farallones in 1972 ( LeBo- ,^

euf, Ainley, and Lewis 1974), and the South Shetland fur seal, Arctocephalus '

NOTES

tropicalis gazella (Peters), established itself at Cape Shireff in the South Shetland
Islands (O'Gorman 1961).

FIGURE 1. Female Zaiophus californianus with pup on Southeast Farallon Island, July 10, 1974.
Photograph by author.

- ..,.^^'

■■^'■-^

i**^

UA^

66 CALIFORNIA FISH AND CAME

Even more encouraging is the fact that T. James Lewis reported the birth of
a California sea lion pup from Southeast Farallon Island in June of 1975. We do
not know if this is the same female observed in 1974, but if so, this indicates that
the female not only gave birth on the Farallones, but was impregnated there as
well. There is evidence from archaeological digs that California sea lions may
have bred on these islands in the last century, but were eliminated by sealers.
It is to be hoped that this sad tale is being reversed today through the combined
efforts of the Point Reyes Bird Observatory and the U.S. Bureau of Sport Fisheries
and Wildlife to maintain the Farallones as a national wildlife refuge.

REFERENCES

Hancock, D. 1970. California sea lion as a regular winter visitant off the British Columbia coast. ). Mammalogy, ,
51: 614.

King, ). 1964. Seals of the world. British Museum of Nat. Hist. London: 154 p.

LeBoeuf, B. ).; Ainley, D. C. and T. ). Lewis. 1974. Elephant seals on the Farallones: population structure of an
incipient breeding colony. ). Mammalogy, 55: 370-385.

O'Corman, F. A. 1961. Fur seals breeding in the Falkland Islands Dependencies. Nature, 192: 914-916.

Peterson, R. S. 1968. Observations of sea lions on Seal Lion Rock, San Luis Obispo County, California, 1968.
University of California, Santa Cruz.

Peterson, R. S. and G. A. Bartholomew. 1967. The natural history and behavior of the California sea lion. Amer.
Soc. of Mammalogists, Spec. Publ., (1): 1-79.

Raymond J. Pierotti, Dept. of Biological Sciences, California State University,
Sacramento 95819; David G. Ainley and T. James Lewis, Point Reyes Bird
Observatory, Box 321, Bolinas, California 94924; and Malcolm C Coulter,
Dept. of Biology, University of California, Davis 95616. Accepted November
1975. This is Contribution # 105 of the Point Reyes Bird Observatory.

OBSERVATIONS ON THE BREEDING BEHAVIOR

OF THE HARBOR SEAL, IN ■

HUMBOLDT BAY, CALIFORNIA

INTRODUCTION

The harbor seal of the eastern Pacific, Phoca vitulina richardi, frequents es-
tuaries, tidal sandbanks, and offshore rocks from Baja California, Mexico to the
northern coast of Alaska (Scheffer 1958). Due to its highly aquatic and secretive,
habits, little is known of the harbor seal's behavior. Quantitative behavioral
studies have relied largely upon the observation of captive animals (Finch 1966;
Schusterman 1968). However, aspects of harbor seal behavior in the wild have
been described by Biggs ( 1 969 ) , Bishop ( 1 967 ) , Fisher (1952), Newby ( 1 973 ) ,
Scheffer and Slipp (1944), and Venables and Venables (1955, 1957, and 1959).

This is a report on a 300-hr study of a pupping colony of harbor seals in
Humboldt Bay, California (Lat 40° 45' N, Long 124° 10' W) during the spring of
1973. The southern part of the bay is a shallow body of water, 4 miles long and
2 miles wide, with deep channels along which seals haul out during each low
tide. I made daily observations of these animals between March and June from
an observation tower located within the rookery. Binoculars (7X50) and a
spotting scope (40X) aided observations which were usually at distances of 20
to 100 m (66 to 330 ft). A blind mother and her 10-day old pup were marked
with a lanolin-emulsion sheep marker (Kemp's Branding Liquid, William Cooper
and Nephews, Chicago).

NOTES 67

OBSERVATIONS

The Pupping Colony

Seasonal movements of seals into South Bay began in the first months of the

year. By March 23, 1973, when the first pup appeared, there were 67 seals; by

April 26, the number of pups had peaked at 88 and there were 337 seals in the

bay.

The scattered herds of the colony were open groups, showing changes in
composition, number, and location as they broke up with each high tide and
reformed on the ebb.

Although harbor seals show some sexual dimorphism in body size (Biggs
1969), I was able to sex seals only by determining the location of genital open-
ings as the animals rested on land. Usually, herds included males, females,
yearlings, and mothers with pups, as was the case in Mugu Lagoon, California
(Evans and Bastian 1969). However, beginning on April 19, I repeatedly ob-
served herds in which every seal that could be sexed was an adult male
(Table 1).

TABLE 1. Observations of Male Herds in South Humboldt Bay.
Q^fp Herd size Males Females Total sexed

4/27/73 13 6 0 6

5/21/73 13 12 0 12

5/28/73 23 13 0 13

5/30/73 11 7 0 7

Males in these herds often bore scars about the face and neck, and sometimes
had erections as they rested on their sides. Such nonrandom associations of
sexes suggest the presence of breeding competition between males, leading to
the formation of bachelor herds of subordinate males. Alternatively, sexes may
tend to segregate until females begin to come into estrus, shortly after pups are
weaned ( Bishop 1 967 ) . To my knowledge, male groups of harbor seals have not
been reported.

Parturition

On April 12, 1973, at 1721 hours, I witnessed the birth of a harbor seal pup.
The female was alone and moved restlessly across the mud flats for about 30
min before the brief delivery. Presentation was cephalic. By the time the pup
struck the mud, the umbilical cord had broken and the amniotic sac had burst.
Simultaneously, two Western gulls, Larus occidentalis, landed nearby but did not
interact with the mother and the newborn pup. The pup was born in juvenile
r pelage.

For 80 min following birth, I recorded the activities of the mother and pup
(Table 2 ) . During this time I saw no sign of afterbirth and no suckling took place.

TABLE 2. Time Sequence of Postnatal Activities of a Harbor Seal Mother and Pup Following
a Birth on April 12, 1973.

Time Mother Pup

0 Lying on belly after 30 min of labor. Emerges head-first.

(Birth)

20 sec Approaches and noses pup. Begins to locomote across mud using

foreflippers

CALIFORNIA FISH AND GAME

Moving and resting on mud

Sniffs mother's abdomen but does not

suckle.

Splashes through shallow water at

edge of channel.

No suckling.

No suckling; swims into deep water.

Swimming and diving near mother.

Dives for 30 sec.

Rides piggyback, then swims from

mother.

Rides piggyback, then swims from

mother.

The newborn pup displayed extremely precocial behavior. It moved actively
on the mud within the first minute after birth. It entered shallow water at 10 min
post partum. It swam independently in deep water from 20 min post partum until
the observation ended at dusk.

Postnatal interactions between mother and pup involved frequent nose-nose
contact on land (e.g. nosing for 45 sec of a 1-min observation at 4 min post
partum) and in water. The mother did not lick or groom her pup. All perinatal
activity took place in the absence of other seals.

Births of harbor seals have been reported by Bishop (1967) and Klinkhart
(1967). All births recorded for P. v. r/'chard/ appear to have been cephalic
presentations and terrestrial.

4 min

Waves foreflipper at pup and contin-

ues nosing

7 min

Rolls on side in nursing position.

10 min

Follows pup through shallow water.

13 min

Rolls on side in nursing position.

20 min

Rolls on side in nursing position.

30 min

Swimming after pup and nosing pup

after dives.

40 min

First mutual nosing in water.

55 min

Carries pup briefly on her back for first

time.

70 min

Carries pup briefly on her back.

80 min

Observation ends at dusk.

S^'^^""

FIGURE 1.

A harbor seal mother nurses her 6-day old pup on the mud flats of Humboldt Bay.
Photograph by the Author (1973).

NOTES 69

Mother-pup Bond

Observations of the marked mother and pup suggest a maternal bond that is
highly specific. The two seals were always seen together until weaning. Only
once did a strange pup attempt to suckle the mother; the mother rebuffed the
attempt with foreflipper waves and bites.

The maternal bond was apparently maintained by the pup's unilateral vocali-
zations, as well as by visual and olfactory cues. Mothers and pups were together
continuously and were not bound to specific herds.

Mothers with pups did not regurgitate after hauling out on the ebb as did many
other seals; and because some mothers became noticeably emaciated through
the lactation period, it appears that mothers may have fasted or fed only sparing-
ly during the continuous mother-pup nursing bond.

All observed nursing occurred on land or in a few inches of water ( Figure 1 ) ,
although aquatic nursing has been reported in harbor seals (Finch 1966; Vena-
bles and Venables 1955). Nursing periods were usually spaced several hours
apart during low tide haul-out. The mean length of a nursing period was 6.6 min
(S.D. = 3.4) for 23 observations.

Pups initiated these periods by nosing their mothers' abdomens and terminat-

'ed them by simply ceasing to suckle. Mothers initiated nursing periods by rolling

on their sides to expose abdominal teats and terminated them by rolling back

on their bellies. Mothers sometimes used foreflipper waves, a familiar harbor seal

threat, to regulate the duration of suckling by pups.

The marked pup was weaned at between 5 and 6 weeks of age.

Pup Ontogeny

Suckling pups could be roughly aged on the basis of changes in body size,
manner of locomation on land, and condition of the umbilical cord remnant
(Knudtson 1974). The marked pup lost the 8- to 10-cm (3- to 4-inch) cord
remnant at between 8 and 10 days of age.

Pups as young as 6 days old displayed a crude version of the adult foreflipper
wave. Pups rode piggyback on their mothers' backs in the water as early as 55
min post partum. Some pups were slapping the water with their foreflippers
when disturbed, in the manner of adult harbor seals, by the 3rd week following
birth. Suckling pups dove for as long as 2 min.

Copulation

Throughout the study period I repeatedly observed stereotyped aquatic in-
teractions between unsexed pairs of seals. Twice they included dog-like mounts
by one of the pair. These encounters were characterized by deliberate foreflip-
iper and hindflipper slaps, nuzzling and biting, and synchronous rolling dives.
They resembled descriptions of courtship in P. v. vitulina by Venables and
Venables (1957), although Bishop (1967) suggests that such rolling encounters
are probably incipient sexual behavior or play rather than actual breeding in-
teractions.

CONCLUSIONS

Although data is still lacking for an adequate description of the harbor seal

breeding system, its principal features appear to include: an open herd structure

with a distinct absence of territorial or harem maintaining activity; possible

male-exclusion pressures, as evidenced by herds of males; an aquatic copulation

70 CALIFORNIA FISH AND CAME

(Bishop 1967; Venables and Venables 1957); a continuous mother-pup nursing
bond that is uninterrupted by copulation or abandonment until weaning; a
terrestrial nursing-suckling relationship; a maternal aggressiveness towards other'
adults (Knudtson 1974); and an estrus that occurs shortly after weaning (Bishop
1967).

Such features could best be encompassed within a promiscuous breeding plan
in which adult males compete for cows entering the post-weaning estrus. In such
a system, competition between rival males could lead to bachelor herds of
subordinate males and mothers would become receptive to the advances of
dominant males only after pups were weaned. Males would than consort with
females approaching estrus, forming transient tending-bonds culminating in
copulation. Because females would no longer be bound to land-based nursing
duties, copulation would usually be aquatic. Opportunistic breeding by males
would lead to greater reproductive success than would territoriality in this com-
petition for mobile aquatic females.

Other studies have suggested both promiscuity (Scheffer and Slipp 1944) and
monogamy (Evans and Bastian 1969) as the basis for a harbor seal breeding
system. Long term studies of harbor seal breeding strategy using tagged seals
remain to be carried out.

ACKNOWLEDGMENTS
I gratefully acknowledge the assistance of Daniel Brant in criticizing this
manuscript and of Warren J. Houck in providing advice throughout the study, |
which was part of a graduate research project at Humboldt State University,
Areata, California.

REFERENCES

Bigg, M. A. 1969. The harbour seal in British Columbia. Canada, Fish. Res. Bd., Bull., (1972): 1-33.

Bishop, R. H. 1%7. Reproduction, age determination, and behavior of the harbor seal, Phoca vitulina L., in the

Gulf of Alaska. Unpublished M.S. thesis, Univ. Alaska, College, Alaska. 121 p.
Evans, W. E. and j. Bastian. 1969. Marine mammal communication: social and ecological factors, p. 425-475.

In H. T. Andersen (ed.). The biology of marine mammals. Academic Press, New York and London. 511 p.

Finch, v. A. 1966. Maternal behavior in the harbor seal. Unpublished M.A. thesis, San Francisco State College,
S.F. 94 p.

Fisher, H. D. 1952. The status of the harbour seal in British Columbia with particular reference to the Skeena

River. Canada, Fish. Res. Bd., Bull., (93): 1-58.
Klinkhan, E. C. 1967. Birth of a harbor seal pup. j. Mammal., 46(4): 677.
Knudtson, P. M. 1974. Mother-pup behavior within a pupping colony of harbor seals (Phoca vitulina richardi)

in Humboldt Bay, California. Unpublished M.A. project, Humboldt State University, Areata, Calif. 42 p.

Newby, T C 1973. Observations on the breeding behavior of the harbor seal in the state of Washington.
I. Mammal., 54(2): 540-543.

Scheffer, V B. 1958. Seals, sea lions, and walruses. Stanford University Press, Stanford, Calif. 179 p.

Scheffer, V. B. and |. W. Slipp. 1944. The harbor seal in Washington State. Amer. Midi. Nat., 32: 373-416.

Schusterman, R. j. 1968. Experimental laboratory studies of pinniped behavior, p. 87-171. In R. J. Harrison et

al (eds.). The behavior and physiology of pinnipeds. Appleton-Century-Crofts, New York. 411 p.
Venables, U. M. and L. S. V. Venables. 1955. Observations on a breeding colony of the seal Phoca vitulina in

Shetland. Zool. Soc. London, Proc., 125: 521-532.

1957. Mating behavior of the seal Phoca vitulina in Shetland. Zool. Soc. London, Proc., 128: 387-3%.

1959. Vernal coition of the seal Phoca vitulina in Shetland. Zool. Soc London, Proc., 132: 66S-669.

Peter M. Knudtson, Star Route, Trinidad, California 95570. Accepted November,
1975.

NOTES 71

NOTES ON SOME FISHES COLLECTED OFF THE
;j OUTER COAST OF BAJA CALIFORNIA

J The four fishes listed in this report represent geographic range extensions and
definite collection localities. The fishes were collected by the author in otter

■ trawls aboard the Departnnent of Fish and Game research vessel N.B. SCOFIELD
and by Los Angeles County Museum personnel, in otter trawls, aboard the

, research vessel SEARCHER. Latitudes and longitudes have been included for all

(Collecting localities (Table 1 ). Miles are in nautical miles.

TABLE 1. Latitudes and Longitudes of Localities of Capture (Arranged from North to South)

Locality Latitude Longitude

Baja California

Ballenas Bay (12.6 km SE of Abreojos Point) 26°36.4'N. 113°33.2'W.

Ballenas Bay (20.4 km SE of Abreojos Point) 26'"31,3'N. n3°35.rvy/.

San luanico Bay (5.6 km SE of Pt. Pequena) 26''12.8'N. 112°25.8'V^.

Magdalena Bay (4.6 km S of Pt. Redonda) 24''28.5'N. 112°02.5'W.

Tosca Point (37.0 km SE) 24°12.0'N. 1ir22.0'W.

' Tosca Point (64.8 km SE) 24''07.0'N. liroS.O'W.

Marquez Point (9.2 km W) 23''57.0'N. 110°58.0'W.

, Marquez Point (37.0 km SE) 23°38.0'N. n0''43.0'W.

Raja inornata (Jordan and Gilbert) — California skate

One California skate was captured 13 km (6.8 miles) SE of Abreojos Point on
March 13, 1975, in 57 m (31 fm) of water. The total length of the skate was 480
mm (18.9 inches) and the wing length was 319 mm (12.6 inches). My identifica-
tion was confirmed by Carl L. Hubbs, Scripps Institution of Oceanography, La
jolla, California. This specimen is now in the ichthyological collection at Scripps
Institution of Oceanography (SIO 75-379).

This fish extends the known range southward approximately 176 km (95
miles) from Turtle Bay (Miller and Lea 1972) to Ballenas Bay.

Zaniolepis latipinnis Girard — longspine combfish
On March 13, 1975, a longspine combfish was captured 20.4 km (11.0 miles)

SE of Abreojos Point in 91 m (50 fm) of water. The total length of the specimen

was 143 mm (5.63 inches) and the standard length was 124 mm (4.88 inches).
' The occurrence of the longspine combfish off Abreojos Point extends the

range south from San Cristobal Bay, as recorded by Knaggs, Sunada and Lea
' (1974), to Abreojos Point, a distance of 140 km [77 miles).

Oxyjulis californica (Gunther) — senorita

I Seven senorita were captured 5.6 km (3.5 miles) SE of Point Pequena on
;March 11, 1975, in 22.0 m (12 fm) of water. The specimens were inadvertently

thrown overboard before any measurements could be taken.
The previous southern limit of their range was Cedros Island (Miller and Lea

1972). The capture of these fish off Point Pequena extends their southern range

366 km (198 miles).

Prionotus gymnostethus (Gilbert) — searobin

On March 10, 1975, two specimens were captured by Department of Fish and
"Game personnel 4.6 km (2.5 miles) Sof Point Redonda in 80 m (44fm) of water.
' The specimens were identified by John Fitch (CF&G). They measured 100 and

101 mm (3.94 and 3.97 inches) standard length (SL) and are now deposited in

the collection of the Natural History Museum of Los Angeles County (LACM

34355-1).

72 CALIFORNIA FISH AND GAME

While looking for other individuals of this species it was learned (J. Fitch, pers.
commun.) that the Los Angeles County Museum of Natural History had speci-
mens collected from the outer coast of Baja California on which no range
extensions had been published. Therefore, I have included their collections of
this species with ours.

The following specimens were all captured with a 4.9-m (16-ft.) otter trawl
on February 1, 1971, in different localities, by Los Angeles County Museum
personnel aboard the research vessel SEARCHER. These specimens are located
in the ichthyological collection at the Los Angeles County Museum. Two speci-
mens (LACM 31770-4) measuring 79 and 92 mm (3.1 and 3.6 inches) sl were
captured 37 km (20 miles) SE of Point Tosca in 84 m (46 fm) of water. Two
smaller specimens (LACM 31771-10) of 18 and 26 mm (0.7 and 1.0 inches) SL
were taken 65 km (35 miles) SE of Point Tosca in 26 m (14 fm) of water. Two
more specimens (LACM 31772-4) of 91 and 110 mm (3.6 and 4.3 inches) SL
were captured 9 km (5 miles) W of Point Marquez in 76 m (42 fm) of water.
Six specimens (LACM 31773-7) ranging in size from 72 to 105 mm (2.8 to 4.1
inches) were taken 37 km (20 miles) SE of Point Marquez in 110 m (60 fm)
of water.

Walker and Norris (1952) report the northern limit of this species range as
being the Gulf of California. This is the first time this species has ever been
reported from the outer coast of Baja California and represents an extension of
276 km (150 miles) northward from the southernmost tip of Baja.

ACKNOWLEDGMENTS
I wish to gratefully acknowledge the assistance of Ralph Rodrigues, Milan
Marott, and the rest of the crew on the N.B. SCOFIELD. I especially want to
express may thanks to John Fitch for his assistance in identifying specimens and
for his suggestions concerning the manuscript. I would also like to thank Robert
j. Lavenburg, Curator of Fishes at the Los Angeles County Museum of Natural
History, for allowing me to publish information concerning specimens collected
by the museum and for his suggestions concerning the manuscript.

REFERENCES

Knaggs, Eric H., John S. Sunada and Robert N. Lea. 1975. Notes on some fishes collected off the outer coast
of Baja California. Calif. Fish Game, 61 (1 ): 56-59.

Miller, Daniel J., and Robert N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Dept. Fish and
Came, Fish Bull., (157): 1-235.

Walker, Boyd W. and Kenneth S. Norris. 1952. Provisional check list of fishes of the Gulf of California. Calif.
State Univ., Los Angeles. 42 p.

Glenn F. Black, Operations Research Branch, California Department of Fish and
Game, 350 Golden Shore, Long Beach, Calif 90802. Accepted March 1976.

73
BOOK REVIEWS

Mammals of the World

By E. P. Walker, F. Warnick, S. E. Hamlet, K. I. Lange, M. A. Davis, H. E. Uibie, and P. F. Wright. The
Johns Hopkins University Press, Baltimore, 1975. hxlviii + 1-644; 2:viii + 647-1500; illustrated. Third
edition, revised by John L. Parodiso. $37.50.

The third edition of Mammals of the World W\\\ remain a useful reference tool, just as the first
and second editions were. The first edition (1964) went through two printings; the second edition
was published in 1968. The current edition is similar in format to the previous two, but because of
the impracticality of updating Volume III, a classified bibliography of world-wide mammalian litera-
ture, it has been eliminated. The bibliography at the end of Volume I remains unchanged. Where
new references appear, citations have been incorporated into the text.

Mammals of the H/oz-Zc/ includes accounts of 1,050 genera, as well as brief ordinal and familial
descriptions. Approximately 2,000 figures illustrate the volumes, of which about 270 are new. In
addition to providing a photograph of nearly every extant genus of mammal, closeups and line-
drawings of various anatomical features are included. The text which accompanies each generic
account provides general information on physical characteristics and natural history. Unfortunately,
the text does not provide adequate comparative information which would readily allow the reader
to distinguish between genera.

Mammals of the World\N\\\ continue to warrant a place on the bookshelves of interested laymen,
and in the libraries of wildlife biologists. Amateur naturalists will find it fascinating reading, and it
will remain a valuable reference source for professional scientists. Because of the quality of the
volumes, and the amount of material included, this work is a bargain at the asking price. — Vernon
C. Bleich

SHAD FISHING

By C. Boyd Pfeiffer; Crown Publishers, Inc., 1975, 177 p., illustrated, $8.95.

The popularity of sport fishing for shad is growing extremely rapidly on both coasts, and the need
for a complete book on shad angling is strongly felt by novices and experts alike. C. Boyd Pfeiffer
has filled this need by producing a classic which is bound to become the bible for shad anglers.

He discusses the history of shad fishing, summarizes the biology and life history, and devotes most
of the book to the proper tackle, equipment, flys and lures, and techniques for catching shad.
Although the emphasis of his book is on the Eastern Seaboard, it also covers fishing on the West
Coast, and the techniques and tackle described are applicable on both coasts. A large list of fly
patterns is included in his treatise with instructions for tying them.

After he has guided you to the best locations, taught you the techniques of catching shad, and
equipped you properly, he then proceeds to give you lessons in preparing shad for gourmet recipes,
which are also included in this complete guide. It is in this section where I have a minor, and perhaps
trivial, disagreement with the C. Boyd Pfeiffer. He presents what he refers to as two methods of
boning shad. The first, which he indicates is much simpler, is presented with photographs. Although
he describes this method very simply, he may not cover it in sufficient detail to enable a novice to
bone shad. Also, his "simpler method" does not remove the row of bones along the center of the
fillet.

The alternate method (that described by the California Department of Fish and Game) is given
by Pfeiffer without photographs and labeled "more complex". Aside from the removal of the lateral
strip of bones by what he refers to as the "more complex method", there is really very little
difference in the two techniques. However, the method discussed by CF&G describes the similar
process in much greater detail and was originally given with many photographs. His gourmet recipes
appear to be excellent, and I can't wait to try some of them.

This book should prove invaluable to anyone wanting to learn about shad fishing and will be a
valuable addition to the bookshelf of the veteran shad angler. — John Radovich

The Fishes of Missouri

By William L. Pflieger; Missouri Dept. Cons., 1975; viii -|- 343 p. profusely illustrated; soft cover $7.50,
hard cover $10.00.

Written by a professional biologist. The Fishes of Missouri \s, a very comprehensive volume which
will provide a wealth of information for Missouri sportsmen and biologists alike. The illustrated keys
to the 26 families of fishes found in Missouri quickly lead the reader to the correct generic /specific
key. At the start of each chapter is a brief discussion of a particular family of fishes, then the illustrated
generic /specific key which directs the reader to a page for detailed information on an individual
species. The information for a species includes the common and scientific names, a description.

74 CALIFORNIA FISH AND CAME

distribution maps, and a discussion of distribution, habitat, habits, life history, and the species'
importance to man. Fifteen pages of colored, underwater photographs, a glossary, and reference
section, combined with excellent drawings in the keys by Lynne Taylor, make this an excellent,
easy-to-use book. — K. A. Hashagen, Jr.

The Soft-Hackled Fly

By Sylvester Nemes; Chatham Press, Old Greenwich, Conn., 1975; 130 p. color plates and black and white
photographs; soft cover $3.95, hard cover $7.95.

Not a new type of fly and no special equipment or innovative techniques are required to catch
fish on it — the soft-hackled fly. Mr. Nemes discusses the history of this sparsely dressed, wingless
wet fly; provides a detailed photographic sequence illustrating the tying of a number of his more
successful patterns; and relates how, when, and where to fish his patterns. Nothing new, but a
method of fishing that has fallen into disuse (and to some extent, disrepute) with the advent of the
no hackles, emergers, skittering caddis, etc. Mr. Nemes fishes with no other flies and catches fish
where others fail using the "traditional" techniques; I intend to tie up a few and give 'em a try — who
knows! — K. A. Hashagen, Jr.

The Practical Fly Fisherman

By A. J. McClane; Prentice Hall, N.J., 1975; x + 271 p. 4 color plates; $10.00.

If I were asked to recommend a single book for a beginning fly fisherman, The Practical Fly
Fisherman would definitely be the book. There are two main reasons I would pick this book over
the many fly fishing books available. First, A! McCiane is the expert's expert on matters of fly fishing.
McClane first wrote this book in 1953 and updated it for this 1975 reissue; it required very little
updating. His philosophies have stood the test of time, his predictions have become fact, and his
techniques have remained unchanged. Second, McClane can write. He knows his subject and he
knows words. I enjoy reading his publications both for the knowledge and the style of writing.

The initial four chapters are about equipment and its use — rods, lines, leaders, and reels, and a
detailed, but easy-to-read chapter on casting. Five chapters discuss the various types of flies and how
to fish them. Fly fishing for bass and panfish are the subject of two additional chapters. Each chapter
has been updated at the end, which allows the reader to be aware of the time differential between
editions. The price has increased from $5.95 to $10.00, but it is well worth the increased price. —
K. A. Hashagen, Jr.

Culture of Marine Invertebrate Animals

Edited by W. L. Smith and M. H. Chanley; Plenum Press, New York and London, 1975; 337 pp.. Illustrated.

This book is based on presentations at the conference on Culture of Marine Invertebrate Animals
held in Greensport, New York in October, 1972. A total of 20 papers by 36 contributors are inclusive.
Contributors include a number of recognized authorities of marine invertebrate culture. Although
the subject matter is broad, the book is conveniently divided into two parts.

Part I, consisting of seven papers, delves into the supportive aspects of marine culture. Topics
include recirculating system culture methods, maintenance of marine filter feeders, phyto-plankton
culture, pathogens associated with cultured bivalve mollusk larvae, marine microbiology relative to
aquaculture and the use of antibiotics in the culture of marine invertebrates. The latter subject matter,
the paper on phytoplankton culture, and the presentations on bacterial pathogens, and marine
microbiology are outstanding, and will be most-welcomed by those engaged in aquaculture investi-
gations.

Part II is comprised of specific culture techniques for a wide selection of invertebrates representing
several phyla. Beginning with the coelenterates and proceeding to the bryozoa, polychaetes, Crus-
tacea, echinoderms and mollusks, general culture procedures are outlined. In certain instances the
culture methods presented for a group are essentially a review (e.g. coelenterates); while me-
thodology discussed for crustacean and molluscan forms represent more recent advances in culture
practices.

Whether one is engaged in University level research, in a relatively small-scale experimental
set-up, or a large-scale shell-fish production operation, they will find this book valuable. It represents
one of the most useful recent contributions to the literature of marine invertebrate culture. — Farl E.
Ebert

REVIEWS 75

The Ageing of Fish: Proceedings of an International Symposium

Edited by T. B. Bagenal, Unwin Bros. Ltd., The Gresham Press, Old Woking, Surrey, England, 1974; vi -|-

234 p., illustrated. £5. paper.

Since this symposium was sponsored by The European Inland Fisheries Advisory Commission of
F.A.O., The Fisheries Society of the British Isles, and The Freshwater Biological Association, it follows
that the underlying theme concerns freshwater fishes and fisheries. Twenty-one papers by 22 authors
are grouped under five major categories: Some considerations of the scientific basis of age determi-
nation (6 papers); Mechanical aids to age determination (2 papers); Elimination of errors in age
determination (6 papers); Some sources of age reading errors (2 papers); and The effects of errors
in age determination on subsequent studies (5 papers).

Although some authors had more new information to report than others, and some obviously had
not done their homework as well as they could have, all of the contributions are pertinent and
meaningful. I was especially interested in the information offered in a 12-page report by K. Simkiss
entitled "Calcium metabolism of fish in relation to ageing," and believe that salmonid biologists
(particularly) would do themselves a favor by taking note of his statement that "there is no evidence
for any resorption of otoliths . . ."

Giorgio Pannella offers a great deal of sound advice in his contribution entitled "Otolith growth
patterns: an aid in age determination in temperate and tropical fishes." He explores briefly such
phenomena as daily, bimonthly, monthly, and annual growth, and illustrates these patterns with
some excellent scanning electron micrographs. In light of his comment that "because the daily
journal can be followed in otoliths and not in scales, the precision and amount of data are far superior
in the former," fishery biologists who, historically, have depended upon scale readings might find
it enlightening to investigate otoliths.

One of the weakest (poorest) of the 21 contributions, in my opinion, is a nine-page report by C.
P. Mathews entitled "An account of some methods of overcoming errors in ageing tropical and
subtropical fish populations when the hard tissue growth markings are unreliable and the data
sparse." Confusion as to species involved, questionable ageing techniques, sloppy proofreading, and
other inconsistencies cast serious doubt on the reliability of the information presented.

Generally, however, these are "quality" reports and so much useful information is presented that
this volume should be required as either background or refresher reading for those likely to be
involved in age studies or already involved. — John E. Fitch.

Marine Game Fishes of the Pacific Coast from Alaska to the Equator.

By Lionel A. Walford; Reprint of 1937 edition published by Univ. Calif. Press; with new 19-page introduction;
Smithsonian Institution Press, Washington, D.C. 1974. $15.

Although first published in a limited edition in 1937, out-of-print shortly thereafter, and a collec-
tor's item during the past three decades, Walford's Marine Came Fishes of the Pacific Coast is still
the most helpful publication there is for identifying many of the fishes inhabiting tropical and
subtropical waters between Panama and California. Now, with re-publication, not only is it available
at a price most of us can afford, it is more useful than ever because of a 9-page "addendum" that
updates scientific names, notes changes in common names, lists new species and synonymizes
others.

As pointed out by the publisher "This edition is reprinted from the original without change except
for the addition of a new introduction . . . and color plates printed on both sides of each page."

Upon comparing this reprint with an original, one can see immediately that the color plates lost
nothing in reproduction, but the black-and-white plates now have a dirty grey background.

Although the new information presented in the "addendum" is for the most part priceless, there
are omissions, and some groups have been given better coverage than others. Although printing
errors are scarce, several very minor items could stand correcting. On p. 13, the range for Nematistius
should read San Clemente (city), California to Peru, and on p. 18, Epinephelus niphobles is mis-
spelled. On p. 14, Seriola mazatlana is noted as being of doubtful validity with the suggestion that
it may be synonymous with 5. peruana. My studies of Seriola lead me to believe that S. mazatlana
is a junior synonym of 5. dorsalis. A dwarf species inhabiting nearshore waters off Central America
remains unnamed, but represents a fourth Seriola for the eastern Pacific.

What is needed now is a publication covering all the fishes and fish families inhabiting the highly
productive stretch of ocean between California and Panama. — John £ Fitch.

76 CALIFORNIA FISH AND CAME

Fishes in Kansas

By Frank B. Cross and Joseph T. Collins. University of Kansas, Lawrence, Kansas. 1975. 189 pp. $6.00,

paperback.

This is the second book on fishes of Kansas published by the University of Kansas Museum of
Natural History. The first book. Handbook of Fishes of Kansas, was printed in 1967. It was authored
solely by Frank B. Cross. The second book is intended as a supplement and a companion to the first
book. It is less technical than the first book; for example, there are no keys to species; and it includes
more up-to-date information on the status of each species. The new book is written exclusively in
lay terms, which makes it useful for those who lack technical training. I like the introductory chapters.
They orient the reader to environmental factors that affect fish distribution, the major types of
streams and their fish communities, and man's effect on fishes in Kansas.

The chapter on man's effect on fishes describes impacts on fish habitat and on diversity of species
resulting from intensive agricultural practices. Agricultural practices have been "cleaned up" in
recent years, and deterioration of many streams has been slowed or even reversed. However,
irreversible changes in diversity of species have occurred from construction of numerous impound-
ments throughout the state. Several new species, such as walleye, yellow perch, white bass and
northern pike, have been introduced in Kansas lakes and reservoirs, and they have had an impact
on native fishes.

A key to families of fishes precedes the bulk of the text, which is devoted to accounts of individual
species. Each species account includes: ( 1 ) an artist's rendering of the fish, ( 2 ) descriptive charac-
teristics of the species, (3) a map showing distribution of the species within the state, (4) information
on reproduction and food preference, and (5) a remarks section which serves as a "catch-all" space
provides additional information such as best fishing methods, status of the fish, importance of the
fish, and, occasionally, methods for cooking the fish. — Larry Puckett

Pbotoelectronic componbon by

CALIFOKNU OFFICE OF STATE PHIVTINC

vc 89854— 800 9-76 4,500 LDA

INSTRUCTIONS TO AUTHORS

EDITORIAL POLICY

The editorial staff will consider for publication original articles and
notes dealing with the conservation of the fauna and flora of California
and its adjacent ocean waters. Authors may submit two copies, each, of
manuscript, tables, and figures for consideration at any time.

MANUSCRIPTS: Authors should refer to the CBE Style Manual (third
edition) for general guidance in preparing their manuscripts. Some
major points are given below.

1. Typing — All material submitted, including headings, footnotes,
and references must be typewritten double-spaced on white bond
paper. Papers shorter than 10 typewritten pages, including tables,
should follow the format for notes.

2. Citations — ^All citations should follow the name-and-year system.
The "library style" will be followed in listing references.

3. Abstracts — Each paper will be introduced by a short, concise ab-
stract. It should immediately follow the title and author's namo
and be indented at both margins to set it off from the body of the
paper.

4. Abbreviations and numerals — ^Use approved abbreviations as listed
in the CBE Style Manual. In all other cases spell out the entir^^
word.

TABLES: Each table should be typewritten double-spaced throughout
with the heading centered at the top. Number tables with arabi(!
numerals and place them together in the manuscript following the
references. Use only horizontal rules. See a recent issue of California
Fish and Game for format.

FIGURES: Submit figures at least twice final size so they may be reduced
for publication. Usable page size is 4f inches by 7f inches. All figures
should be tailored to this proportion. Photographs should be submitted
on glossy paper with strong contrasts. All figures should be identified
with the author's name in the upper left comer and the figure number
in the upper right comer. Markings on figures should be in blue pencil
or grease pencil, as this color does not reproduce on copyfilm. Figure
captions must be typed on a separate sheet headed by the title of the
paper and the author 's name.

PROOF AND REPRINTS: Galley proof will be sent to authors approxi-
mately 60 days before publication. Fifty reprints will be provided free
of charge to authors. Additional copies may be ordered through the
editor at the time the proof is submitted.

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