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Full text of "California fish and game"

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CAUFDRNIA 
FISH- GAME 

"CONSERVATION OF WILDLIFE THROUGH EDUCATION" 




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

Subscriptions may be obtained at the rate of $5 per year by placing an 
order with the California Department of Fish and Game, 1416 Ninth Street, 
Sacramento, California 95814. Money orders and checks should be made out 
to California Department of Fish and Game. Inquiries regarding paid sub- 
scriptions should be directed to the Editor. 



Complimentary subscriptions are granted, on a limited basis, to libraries, 
scientific and educational institutions, conservation agencies, and on exchange. 
Complimentary spbscriptions must be renewed annually by returning the post- 
card enclosed with each October issue. 



Please direct correspondence to: 

Perry L. Herrgesell, Ph.D., Editor 
California Fish and Game 
1416 Ninth Street 
Socromento, California 95814 



u 













V 



VOLUME 69 



APRIL 1983 



NUMBER 2 




Published Quarterly by 

STATE OF CALIFORNIA 

THE RESOURCES AGENCY 

DEPARTMENT OF FISH AND GAME 

—LDA— 



STATE OF CALIFORNIA 
GEORGE DEUKMEJIAN. Governor 



THE RESOURCES AGENCY 
GORDON VAN VLECK, Secretary for Resources 



FISH AND GAME COMMISSION 

NORMAN B, LIVERMORE, JR., President 
San Rafael 

WILLIAM A. BURKE, Ed.D., Vice President ABEL C. GALLETTI, Member 

Los Angeles Los Angeles 

BRIAN J. KAHN, Member ALBERT C. TAUCHER, Member 
Santa Rosa Long Beach 



DEPARTMENT OF FISH AND GAME 
E. C. FULLERTON, Director 

1416 9th Street 
Sacramento 95814 



CALIFORNIA FISH AND GAME 

Editorial Staff 

Editorial staff for this issue consisted of the following: 

Anadromous Fish Kenneth A, Hashagen, Jr. 

Inland Fisheries Ronald J. Pelzman 

Mahne Resources Robert N. Lea 

Wildlife Terry Mansfield 

Wildlife Ronald M. Jurek 

Editor-in-Chief Perry L. Herrgesell, Ph.D. 



CONTENTS 



67 



Page 



Contribution of Cutthroat Trout in Headwater Streams to the 

Sea-Run Population John H. Michael, Jr. 68 

Benthic Invertebrates of the Earthen Coachella Canal, Califor- 
nia Paul C. Marsh and Carolyn R. Stinemetz 11 

Osteophagia and Antler Breakage Among Roosevelt Elk 

R. Terry Bowyer 84 

Concurrent Measurement of Intertidal Environmental Varia- 
bles and Embryo Survival for the California Grunion, Leures- 
thes tenius, and Atlantic Silverside, Menidia menidia 
(Pisces: Atherinidae) .. D. P. Middaugh, H. W. Kohl, and L. E. Burnett 89 

Age, Growth, Reproductive Characteristics, and Seasonal 
Depth Distribution of the Spotfin Surfperch, Hyperproso- 
pon anale Donald M. Baltz and Elaine E. Knight 97 

Hazards to Geese from Exposure to Zinc Phosphide Rodenti- 
cide Baits James F. Glahn and Larry D. Lamper 105 

Ova Fertility Relative to Temperature and to the Time of Ga- 
mete Mixing in the Red Abalone, Haliotis rufesens 

Earl E. Ebert and Randall M. Hamilton 115 

Notes 

First Californian Record of the Amarillo Snapper, Lutjanus 
argentiventris James E. Phelan 121 

Evidence of Birth of a Sea Otter on Land in Central California 

Ronald J. Jameson 122 

Age and Growth and Length-Weight Relationship for Flathead 
Catfish, Pylodictis olivaris, from Coachella Canal, South- 
eastern California 

Mark S. Pisano, Mary J. Inansci, and W. L. Minckley 124 



68 CALIFORNIA FISH AND CAME 

Calif. Fish and Came 69 ( 2 ) : 68 -76 1 983 

CONTRIBUTION OF CUTTHROAT TROUT IN 
HEADWATER STREAMS TO THE SEA-RUN POPULATION ^ 

JOHN H MICHAEL, JR ^ 

Snow Creek Research Station 

Star Route 2, Box 513 

Port Townsend, Washington 98368 

This study was designed to assess the contribution of populations of cutthroat 
trout in headwater areas of three creeks to anadromous cutthroat populations. 

Cutthroat living upstream of permanent barriers to anadromous fish migration in 
Snow and Andrews creeks are resident fish which do not migrate to saltwater. In 
Salmon Creek, anadromous cutthroat penetrate farther into a watershed than either 
steelhead trout or coho salmon and rear sympatrically with resident cutthroat popu- 
lations. Consequently, some fish present in these headwater areas will migrate to 
saltwater. 

Cutthroat present in streams with indefinite or intermittent migration barriers 
(e.g., Salmon Creek) may be anadromous. In this study, outmigrant cutthroat 
marked in the Salmon Creek study area are probably the progeny of anadromus 
cutthroat, not migrants from a resident population. A method to identify resident 
and anadromous cutthroat juveniles must be developed in order to more clearly 
define the distribution of anadromous cutthroat trout populations. 

INTRODUCTION 

Coast cutthroat trout, Salmo clarki clarki, range from northern California to 
southeastern Alaska (Hart 1973). Within a watershed there may exist sympatric 
and allopatric populations of resident and anadromous cutthroat (DeWitt 1954; 
Royal 1972; Scott and Crossman 1973; Moring and Lantz 1975; and Jones 1979). 
Hartman and Gill (1968) found cutthroat generally occupying smaller tributary 
and headwater streams, especially when steelhead trout, 5, gairdneri, were 
present in the system. Lowry (1965) found age 0+ cutthroat abundant in small 
tributaries within a stream system. Royal (1972), Edie (1975), and Jones (1979) 
speculated that resident cutthroat populations may contribute to sea-run popula- 
tions. Moring and Lantz (1975) reported a substantial downstream migration of 
cutthroat juveniles from an area upstream of two "barrier" falls; however, the 
destination of these migrants was undetermined and the nature of the barrier was 
poorly defined. Cedarholm and Tagart (Univ. of Wash., research biologists, pers. 
commun.) reported anadromous cutthroat adults captured upstream of what 
they had previously considered to be an anadromous migration barrier. This 
study was initiated to assess the contribution of cutthroat trout inhabiting head- 
water areas of three separate streams to the sea-run cutthroat population and 
to contribute to the knowledge of the life history of coastal cutthroat, which has 
been inadequately studied. 

STUDY AREAS 
Snow Creek, its main tributary Andrews Creek, and Salmon Creek are located 
on the northeastern portion of the Olympic Peninsula and drain into the Strait 



' Accepted for publication September 1981. 

^ Mr. Michael's current address is; Washington Departnnent of Fisheries, Harvest Management Division, Room 1 1 5 
General Administration Building, Olympia, WA 98504. 



CUTTHROAT TROUT IN HEADWATER STREAMS 



69 



of Juan de Fuca (Figure 1). The Washington Department of Game operates 
permanent fish traps near the mouths of Snow and Salmon creeks. The traps are 
designed to trap all migrating salmonids longer than 300 mm fork length (fl) 
year-round and greater than 50 mm fl from March through August. Study areas 
were located upstream of 20-m single-step falls in Snow Creek, a steep bedrock 
chute with a 6-m drop at an angle of 60° or greater in Andrews Creek, and 
upstream from a series of log jams, boulder jams, and cascades in Salmon Creek. 
The difference in streambed elevation between the up and downstream sides of 
the jams in Salmon Creek was 2-4 m. Preliminary sampling of each study section 
failed to find steelhead and coho, Oncorhynchus kisutch, implying a lack of 
penetration by anadromous fish. 



VICINITY MAP 



Strait of 
Juan de Fuca 




I STUDY AREA 

▲ FISH TRAP 



MAXIMUM OBSERVED PENETRATION OF 
STtELHEAD TROUT AND COHO SALMON 



CROCKER LAKE 



1 km 



FIGURE 1. Location of study areas in Snow, Andrews, and Salmon creeks. 



Anadromous cutthroat trout in Snow and Salmon creeks are the late-entry 
variety (Johnston and Mercer 1976). Adult cutthroat upstream migration peaks 
during January through April. Smolt migration peaks during May but occurs 
March through July. 

METHODS 
Cutthroat from the study areas were collected using a battery powered back- 
pack electrofisher. All fish were measured to the nearest millimetre fork length, 
fin clipped, and released. 



70 



CALIFORNIA FISH AND CAME 



Cutthroat trout juvenile outmigrants captured in Snow and Salmon creeks' 
traps were measured to the nearest millimetre fork length and examined for 
marks. A subsample was weighed to the nearest 0.1 g wet weight. Condition 
index, K, was calculated by the formula: 
l<^ _ 1 0^ wet weight 

Length ^ 

In 1978 all outmigrants trapped at Snow Creek were given a left maxillary clip 
and all outmigrants trapped at Salmon Creek were given a right maxillary clip. 
In 1979 a freeze brand was applied to the left side of all outmigrants trapped at 
Snow Creek and to the right side of all outmigrants trapped at Salmon Creek. 

Cutthroat captured as upstream migrants were measured to the nearest mil- 
limetre fork length, weighed to the nearest gram wet weight, examined for 
marks, and tagged with a numbered monel-metal mandible tag. The sex and 
degree of maturity of the fish were determined by external examination. The 
same procedure was employed for downstream migrating adults. 

Scale samples were collected from a subsample of cutthroat captured in the 
Salmon Creek study area, and a subsample of all cutthroat captured as outmi- 
grants at the Snow and Salmon creek traps. 

Electrofishing surveys were conducted in Snow Creek in the 1 00 m immediate- 
ly downstream from the anadromous barrier during September 1978, to deter- 
mine if marked cutthroat from the study area had descended the falls. Electro- 
fishing surveys were also conducted downstream from the Snow and Salmon 
creeks traps to tidewater during September 1978, to determine if any cutthroat 
outmigrants had remained in freshwater. 

RESULTS 

More than 2,500 cutthroat ranging in size from 33 to 207 mm FL were marked 
in the three study streams over a 1-yr period (Table 1 ). Age analysis of fish in 
the Salmon Creek study area indicated fish up to 4 yr old were present (Figure 
2). While electrofishing during April and May 1978, sexually mature male and 
female cutthroat were collected from the Salmon Creek study area. No adult 
anadromous cutthroat were found in any study area. 



TABLE 1. Number of Cutthroat Trout Marked, Length Range, and Type of Mark for Fish 
Marked in Study Areas in Snow, Andrews and Salmon Creeks. 



Stream 


Date 


Number 
marked 


Length 
range (mm) 


Mark 


Snow Creek system 

Snow Creek 

Andrews Creek 


September 1977 

November 1977 


788 

193 


51-207 
40-186 


Left pelvic 
Right pelvic 


Total 




981 


40-207 




Salmon Creek 


September, 

October 1977 
April, May 1978 
September 1978 


810 

172 
614 


40-182 
51-200 
33-186 


Right pelvic 
Right pelvic 
Right pelvic 


Total 

Total (all systems) 




1,596 

2,577 


33-200 
33-207 





CUTTHROAT TROUT IN HEADWATER STREAMS 



71 



40 



30 

20 

10 
5 

9 
Q 
7 
6 
5 
4 
3 
2 
1 

10 
8 
6 
4 
2 



SALMON CREEK UNMARKED OUTMI GRANTS 




I 



AGE 1 
AGE 2 
AGE 3 
AGE 4 




SALMON CREEK MARKED OUTMI GRANTS 



SALMON CREEK STUDY AREA 




70 80 90 100 UO 120 130 140 150 160 

FORK LENGTH (rm) 



170 180 190 200 210 



FIGURE 2. Ages of cutthroat trout from Salmon Creek, April and May 1978. 

No cutthroat marked in either the Snow or Andrews creeks study areas were 
captured at the Snow Creek trap. Total cutthroat outmigration for Snow Creek 
was small (Table 2). One cutthroat (153 mm fl) marked in the Snow Creek 
study area was found immediately downstream of the falls. 



TABLE 2. 



Numbers, Length, Weight, and Condition Indices (K) for Outmigrant Cutthroat 
Trout Captured in the Snow Creek and Salmon Creek Downstream Traps, 1978 
and 1979. 









Total 
















Year 


Croup 


out- 
migration 


Fork Length (mm) 
N Mean Range 


Wet Weight (g) 


Mean 


Location 


N Mean 


Range 


K 


Snow Creek 


1978 


Unmarked 


25 


25 


178 


121-298 


16 64.3 


19.4-194.8 


0.8172 




1979 


Unmarked 


37 


37 


166 


128-251 


36 47.2 


20.8-136.0 


0.9143 


Salmon Creek 


1978 


Marked 


54 


54 


130 


112-153 


40 20.8 


14.1- 30.2 


0.9463 






Unmarked 


653 


653 


134 


76-257 


425 23.8 


3.9-146.8 


0.9757 




1979 


Marked 


14 


14 


143 


106-162 


14 25.8 


12.^ 41.0 


0.8942 






Unmarked 


226 


226 


143 


7^223 


196 28.5 


7.3-102.1 


0.9235 



72 



CALIFORNIA FISH AND CAME 



Cutthroat marked in the Salmon Creek study area were captured during spring 
smolt outmigration at the Salmon Creek trap. Marked cutthroat outmigrants were 
physically and behaviorally similar to unmarked outmigrants; their length, 
weight, condition (K), ages, and migration timing were all similar (Table 2, 
Figures 2 and 3). 



MARKED OUTMIGRANTS 






UJ 




APRIL 



JUNE 



1978 



1979 



FICURE 3. Timing of capture at downstream migrant trap for outmigrating cutthroat trout in 
Salmon Creek, 1978 and 1979. 



There was no apparent residualism of study area cutthroat outmigrants in 
Salmon Creek as none of the study area outmigrants were captured during 
surveys downstream from the trap. Three sea-run cutthroat originally marked in 
the Salmon Creek study area were recaptured on their migration from saltwater 
to Salmon Creek. One of these fish was later recaptured, spawned out, on its 
return migration to saltwater. All Salmon Creek outmigrant groups demonstrated 
similar saltwater survival rates of 2 to 7% (Table 3). 



CUTTHROAT TROUT IN HEADWATER STREAMS 73 

TABLE 3. Survival from Smolting to First Return to Freshwater for Cutthroat Trout 
Outmigrations from Snow and Salmon Creeks. 

Total First return to upstream trap 

Origin Year Croup outmigration 1978-79 1979-80 Total Percent 

Snow Creek 1978 Unmarked 25 5 5 20 

1979 Unmarked 37 N/ A 4 4 11 

Salmon Creek 1978 Marked 54 1 1 2 4 

Unmarked 653 21 4 25 4 

All Salmon Ck. 707 22 5 27 4 

1979 Marked 14 N/A 1 1 7 

Unmarked 226 N/A 5 5 2 

All Salmon Ck. 240 N/A 6 6 3 

DISCUSSION 

Andrew and Geen (1960) report on the survival rates of various species of 
trout and salmon smolts passing over the spillways of 18 to 90 m high dams. 
Survival rates ranged from 36-98%. The Washington Department of Fisheries 
regularly stocks coho salmon in streams where the resulting smolts have passed 
successfully over barriers of greater heights than those on Snow and Andrews 
creeks (T. Flint, Wash. Dept. of Fisheries biologist, pers. commun.). If there was 
a migration of cutthroat from the Snow Creek study area, it was expected that 
enough of the fish would have survived the passage over the falls and instream 
predation and have arrived at the trap. Outmigration of smolts from Andrews 
Creek is complicated by the presence of Crocker Lake downstream from the 
barrier. A trap operated on the inlet to the lake during the spring of 1977 trapped 
over 200 migrating juvenile cutthroat, one of which passed through the lake and 
was captured in the trap on the outlet stream. Whether the other fish were 
anadromous and eaten by predators or were adfluvial and remained in the lake 
is not known. In any case, no cutthroat marked in the study areas of Snow and 
Andrews creeks migrated to saltwater. Brannon (1967), Northcote, Williscroft, 
and Tsuyki (1970), and Raleigh and Chapman (1971 ) have discussed the influ- 
ence of inheritance on salmonid migration patterns with the basic movement 
pattern being an inherited characteristic. Studies by Miller (1957), Diana and 
Lane (1978), and Lestelle (1978) indicate the home range for resident popula- 
tions of cutthroat is small. In populations of fish which exist upstream of an 
impassable barrier, any fish passing over that barrier is lost to the population. 
Unless the fish spawns prior to its downstream migration, the migratory urge is 
"lethal," as far as the population is concerned. Fish which leave the headwater 
areas of Snow and Andrews creeks are probably random drifters, few in number, 
and make no contribution to the anadromous population. 

Outmigrant cutthroat which had been marked in the study area of Salmon 
Creek are probably the progeny of anadromous cutthroat, not migrants from a 
resident cutthroat population. Marked and unmarked outmigrants were similar 
in many ways (size, age, migration timing, marine survival rates). In 1978 and 
1 979, preseason estimates, obtained by electrofishing, of the number of cutthroat 
smolts present in the presumed anadromous zone of Salmon Creek failed to 



74 CALIFORNIA FISH AND CAME 

indicate the magnitude of the cutthroat outmigration. A large portion of the 
unmarked cutthroat likely migrated from reaches of Salmon Creek upstream of 
the assumed anadromous barrier, but outside of the study area of this experi- 
ment. Although population estimates were not conducted in the Salmon Creek 
study area, evidence from experiments being conducted in Penny Creek (Wash- 
ington State Game Department 1979), a stream inhabited by resident cutthroat 
trout, indicates a rather stable population biomass and stable numerical popula- 
tions of age one and older fish. The stability in numbers of age 1 fish present in 
October and age 2 and older fish present the following April suggests that if there 
is migration from a resident population, it should be stable from year to year 
since the numerical decline is stable. Instead, the number of marked outmigrants 
declined from 1978 to 1979. A more probable explanation of the migration of 
marked cutthroat from the study area to saltwater is that during the spawning 
migrations of 1975-1976 and 1976-1977, adult anadromous cutthroat were able 
to negotiate what we had considered to be a migration barrier. Cedarholm, 
Martin, and Osborne (Univ. of Washington, research biologist, pers. commun.) 
have all observed anadromous cutthroat in reaches of streams thought to be 
inaccessible to them. 

The evidence implies that the "barrier" in Salmon Creek is intermittent or 
non-existent and cutthroat migrating from the study area to saltwater were the 
progeny of anadromous parents. Because no adult anadromous cutthroat were 
captured in the study area of Salmon Creek, it cannot be proven that sea-run 
fish actually spawned in the study area during the study period. Marine survival 
rates measured for Salmon Creek cutthroat are substantially lower than the 20 
to 40% reported by Giger (1972) for an unfished population and 17% reported 
by Jones (1978) for a population considered to be overexploited. It is very 
difficult to detect anadromous cutthroat adults in small streams (J. Johnson, 
Wash. Dept. of Game biologist, pers. commun.). This difficulty, plus the poor 
return rates which resulted in small numbers of adults in the stream, made it very 
unlikely that any anadromous adults would be located during surveys in the 
study area, even if they were present. 

The existence of sympatric spawning populations of resident and anadromous 
cutthroat may lead to some interbreeding; it is not known what effect this would 
have on the migratory patterns of the offspring. Interbreeding may allow the 
genes which determine migration patterns to remain in the population and be 
expressed in the progeny upstream of a newly-created migration barrier. Unless 
anadromous spawners re-invade the area or the fish spawn prior to migration, 
the genetic basis for migration will be removed from the population as each 
migrant passes over the barrier. The final result will be the evolution of a resident 
population of cutthroat trout. 

In the absence of a permanent migration barrier, it should be assumed anadro- 
mous cutthroat could be present in a stream. Currently, there is no way to 
separate juvenile resident and anadromous cutthroat stocks from each other. 
There is a good deal of concern being voiced by research personnel in Washing- 
ton (Johnston 1979) as to the depressed state of sea-run cutthroat stocks, espe- 
cially in those areas of Puget Sound and the Strait of Juan de Fuca most 
accessible to anglers. To determine the status of sea-run cutthroat stocks, a 
method must be developed to differentiate them from resident cutthroat stocks. 



CUTTHROAT TROUT IN HEADWATER STREAMS 75 

Measurements of otolith nuclei (Rybock, Horton, and Koski 1975; and Tippetts 
1979) have been used to differentiate resident from anadromous stocks of 
rainbow trout and may do the same for cutthroat. 

SUMMARY 
Cutthroat trout residing upstream of permanent migration barriers in Snow and 
Andrews creeks were non-anadromous. Cutthroat residing upstream of apparent 
migration barriers in Salmon Creek appeared to be progeny of anadromous 
stock, i.e., the "barrier" probably did not stop migration of adult sea-run cut- 
throat. Cutthroat present in streams with indefinite or intermittent migration 
barriers may be anadromous. It is apparent that to assess the status of sea-run 
cutthroat populations, a method of discriminating between juvenile anadromous 
and resident cutthroat must be developed. 

ACKNOWLEDGMENTS 
S. Elle, T. Johnson, J. Tagart, and R. Woodin assisted in the collection and 
marking of trout and also provided critical comments and suggestions during the 
preparation of this paper. M. Chilcote, J. Johnston, and P. Michael also reviewed 
the manuscript and suggested numerous improvements. P. Knudsen provided 
age determinations through scale analysis. This study was conducted as part of 
a cooperative agreement between the U.S. Fish and Wildlife Service and the 
Washington State Game Department. 

LITERATURE CITED 

Andrews, F.J., and C.H. Geen. 1960. Sockeye and pink salmon production in relation to proposed dams in the 
Fraser River system. Int. Pac. Salmon Fish Comm. Bulletin 11, 259 pp. 

Brannon, E.L. 1967. Genetic control of migrating behavior of newly emerged sockeye salmon fry. Int. Pac. Salmon 

Fish. Comm., Prog. Rept. 16, 31 pp. 
DeWitt, J. W., Jr. 1954. A survey of the coast cutthroat trout, Salmon c/ar/t/ c/drAr/ Richardson, in California. Calif. 

Fish and Game. 40(3): 329-335. 

Diana, J.S., and E.D. Lane. 1978. The movement and distribution of Paiute cutthroat trout, Salmo clarki seleniris, 
in Cottonwood Creek, California. Trans. Amer. Fish. Soc. 107(3):444-448. 

Edie, B.G. 1975. A census of juvenile salmonids of the Clearwater River basin, Jefferson County, Washington, in 
relation to logging. M.S. Thesis, Univ. of Wash., Seattle. 86 pp. 

Giger, R.D. 1972. Ecology and management of coastal cutthroat trout in Oregon. Oregon State Game Comm. 

Federal Aid to Fish Restoration. Project F-72-R. Final Report. 61 pp. 
Hart, J.L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. Bull. 180:740 

Hartman, G.F., and C.A. Gill. 1968. Distribution of juvenile steelhead and cutthroat trout (Salmo gairdneri And S. 
clarki clarki) within streams in southwestern British Columbia. Can., Fish. Res. Bd., J., 25(1):33-48. 

Johnston, J. M. 1979. Sea-run cutthroat; Stillaquamish River creel census (1978) and harvest limit recommendations. 
Wash. Dept. of Game Progress Report. 26 pp. 

Johnston, J.M., and S.P. Mercer. 1976. Sea-run cutthroat in saltwater pens: broodstock development and extended 
juvenile rearing. Wash. State Game Dept. Federal Aid to Fish Restoration, Progress Report AFS-57-1. 92 pp. 

Jones, D.E. 1978. Life history of sea-run cutthroat trout. Alaska Dept. Fish and Game. Anadromous Fish Studies, 
Completion Rept, 1971-1977. Project AFS-42. 18(AFS-42-5-B):78-105. 

'.. 1979. Development of techniques for enhancement and management of anadromous cutthroat trout 

in southeast Alaska. Alaska Dept. Fish & Game. Anadromous Fish Studies, Annual Performance Rept., 1977- 
1978. Project AFS-42. (AFS-42-6-B):69-119. 

Lestelle, L.C. 1978. The effects of forest debris removal on a population of resident cutthroat trout in a small 

headwater stream. M.S. Thesis, Univ. of Wash., Seattle. 86 pp. 
Lowry, G.R. 1965. Movement of cutthroat trout, Salmo c/arAr/c/arAr/ (Richardson), in three Oregon coastal streams. 

Amer. Fish. Soc, Trans. 94(4):334-338. 

Miller, R.B. 1957. Permanence and size of home territory in stream-dwelling cutthroat trout. Can. Fish. Res. Bd., 
J., 14:687-691. 



76 CALIFORNIA FISH AND CAME 

Moring, ).R., and R.L. Lanlz. 1975. The Alsea Watershed study: effects of logging on the aquatic resources of three 
headwater streams of the Alsea River, Oregon, Part 1 -Biological Studies. Federal Aid to Fish Restoration. 
Project AFS-58. Final Report. 66 pp. 

Northcote, T.C., S.N. Williscroft, and H. Tsuyki. 1970. Meristic and lactate dehydrogenase genotype differences 
in streann populations of rainbow trout below and above a waterfall. Can. Fish. Res. Bd., )., 27:1987-1995. 

Raleigh, R.F., and D.W. Chapman. 1 971 . Genetic control in lakeward migrations of cutthroat trout fry. Amer. Fish. 
Soc., Trans. 100(1 ):33-40. 

Royal, L.A. 1972. An examination of the anadromous trout program of the Washington State Came Department. 
Wash. State Came Dept. Final Report. AFS-49. 176 pp. 

Rybock, J.T., H.F. Norton, and K V. Koski. 1974. Use of otoliths to separate juvenile steelhead trout from juvenile 
rainbow trout. Fish. Bull., 73(3):654-659. 

Scon, W.B., and E.). Crossman. 1973. Freshwater fishes of Canada. Fish. Res. Bd. Can. Bull. 184:966 pp. 

Tippetts, W.E. 1979. Evidence of successful reproduction of steelhead rainbow trout, Salmo galrdneri gairdnerl. in 
the Ventura River, California. Calif. Fish Came, 65(3):177-179. 

Washington State Came Department. 1980. Penny Creek coho planting study. Pages 70-84 in. C. Carrison, ed. 
Steelhead program progress report, December 31, 1979. 



BENTHIC INVERTEBRATES OF COACHELLA CANAL ^^^ 

Calif. Fish and Came 69 ( 2 ) : 77- 83 1 983 

BENTHIC INVERTEBRATES OF THE EARTHEN COACHELLA 

CANAL, CALIFORNIA ' 

PAUL C. MARSH 

Center for Environmental Studies 

Arizona State University 

Tennpe, AZ 85287 

and 

CAROLYN R. STINEMETZ^ 

U. S. Bureau of Reclamation 

Yuma Projects Office 

Yuma, AZ 85324 

At least 19 taxa of invertebrates inhabited the Coachella Canal, California, in 
October-November 1980, Dominants were Asiatic clam, Corbicula fluminea; a hy- 
dropsychid caddisfly, Smicridea utico; oligochaetes, Aelosoma sp. and Chaetogaster 
sp.; and chironomid dipterans. Mean densities were from 158 to 3,678 individuals/m^ 
and biomass was 2.02 to 7.63 g dry wt/m^ in mid-channel and near-shore habitats, 
respectively. Invertebrate distributions reflected substrate size and stability, and the 
presence of organic matter. Concrete structures supported populations of S. utico 
and lepidopteran larvae, Parargyractis confusalis, of 25,000 and 1,500/ m', respective- 
ly, far greater than densities of any invertebrate on natural substrates. 

INTRODUCTION 

Macroinvertebrates of North American canals are poorly known despite the 
fact that such systems support substantial fish populations (St. Amant etal. 1974) 
that may depend on such animals for food. The U.S. Bureau of Reclamation has 
conducted investigations of the biota of the Delta-Mendota canal in western 
California (e.g., Prokopovich 1968, Eng 1975), although these data received 
limited distribution. Outside the United States, work has been done on life cycles 
of euryhaline and marine invertebrates of the Baltic Canal (Schutz 1969), and 
molluscs have been studied in the Worchester-Birmingham Canal (Young 
1975), and in irrigation canals of Lombardy (Bianchi et al. 1978). 

Increasing demands for water transport efficiency in the arid American South- 
west has resulted in proposals to line existing earthen canal systems with con- 
crete. Conversion from earth to concrete substrate is an immediate 
environmental alteration. The biological effects of such alterations are not assess- 
able because of a lack of information. This report provides baseline data on 
relative species abundance, biomass, and community structure of invertebrates 
in the earthen Coachella Canal, southeastern California, during autumn. 

METHODS AND MATERIALS 
The Coachella Canal (Figure 1 ) delivers Colorado River water for agricultural 
irrigation in the Imperial, Coachella, and Indio valleys. The canal has a capacity 
of 70.8 m^/sec at the turnout from the All American Canal; this is reduced by 
withdrawals to 36.8 m^/sec 137.8 km downflow. Depths range from 1-5 m 
(mid-channel) and open-reach width is approximately 20 m. The region consists 
of "Colorado Desert" (Jaeger 1957), is mostly below sea level, and lies entirely 
within the endorheic Salton Sea basin. In order to reduce water loss through 
seepage and to increase transport efficiency, the southernmost (upstream) 78.5 
km of canal were re-aligned into a concrete structure in mid-November 1980. 

' Accepted for publication November 1 981 . 

* Present address: Department of Zoology, Arizona State LIniversity, Tempe, AZ 85287 



78 



CALIFORNIA FISH AND CAME 



16 



16 kn 



10 m> 



*Cx 



V 



%. 




All AMERICAN 
CANAL, 



3 2 






^^^^ 



b.h' 



FIGURE 1. Earthen Coachella Canal and southern California location map (inset). Sampling sta- 
tions denoted by closed circles. 

Nine sampling stations on the earthen canal (Figure 1, Table 1 ) were sampled 
by Ekman dredge (0.023 m^) on 23-24 October 1980. Quantitative samples were 
collected along both banks and at mid-channel in depths of < 1 to 3 m. Samples 
were retained on a 420 jutm-mesh sieve and preserved in 10% formalin. Estimates 
of current velocity and qualitative observations of substrate type and aquatic 
vegetation were made at each station. Additional observations were made adja- 
cent to stations 2, 3, and 7 during 10-13 November, when the earthen canal was 
dewatered. Qualitative studies included substrates and vegetation; densities of 
biota associated with concrete structures were estimated within a 0.01 m^ quad- 
rat. 

Laboratory processing included removal of course particles from samples and 
examination at magnification of 7X for removal, enumeration, and identification 
of organisms. Wet weights of invertebrates (en masse except clams) were 
recorded to the nearest milligram after blotting to remove excess water. Weights 
of individual Asiatic clams were recorded after removal from valves (clams 
>4 mm shell length), or following decalcification in 0.1 N HCL (clams <4 
mm). Dry weights were estimated to be 0.1 times wet weight (Winberg 1971 ). 

RESULTS AND DISCUSSION 
General Characteristics 
Substrate was predominately fine to medium sand with sparse, pea-sized 
gravel (Table 1 ); silt or clay was in near-shore habitats where emergent vegeta- 



BENTHIC INVERTEBRATES OF COACHELLA CANAL 



79 



tion reduced current velocity. Concrete structures at check drops, siphons, and 
bridge crossings provided spatially limited, solid substrate. Water velocity was 
relatively uniform (0.3 to 0.7 m/sec) in open reaches, but slower near banks and 
immediately upstream from constrictions. Rooted aquatic vegetation was in 
water <1.0 m deep, and areal coverage was <5.0%. Emergent macrophytes 
were common reed, Phragmites australis, and cat-tail, Typha domingens/s; occa- 
sional beds of sago pond weed, Potamogeton pectinatus, and milfoil, Myriophyl- 
lum spicatum, were present. Water velocity was lower within and near 
vegetation, and substrates in such areas contained particulate organic material 
not present in areas of greater current. Attached filamentous algae, Cladophora 
glomerata, was only on side-walls and aprons of concrete structures. 



TABLE 1. Characteristics of Sampling Stations on the Coachella Canal ^ 

Substrate characteristics 

Station East Mid-channel West 

1 Clayey sand, Sand CPOM ', detritus, 

pebble sand and subm. 

vegetation 

2 Sand, CPOM, Sandy clay Sand, CPOM, 

pebble detritus 

3 Sand Clay Sand 

4 Sand, detritus Clayey sand Sand 

5 Pebbles, sand Clay Pebbles, sand 

6 Sand, FPOM ^ Clayey sand Sand 

7 Pebble, sand. Clayey sand Pebble, sand 

clay 

8 Sandy clay Sand Silt, detritus, 

vegetation 

9 Sand Sand Sand 

' East and west depths less than 1 m, nnid-channel depths 2-3 m; current velocities 0.3-0.7 ni/sec at all stations 

except 8W, which was slack. 
^ CPOM = coarse particulate organic matter, FPOM = fine particulate organic matter. 



Macroinvertebrates 
Seventeen taxa of aquatic invertebrates were collected on 23-24 October 
(Table 2). Asiatic clam, C. fluminea; oligochaetes, Aelosoma sp. and Cha- 
etogaster sp.; chironomid midges; and a hydropsychid caddisfly, 5. iy//co collec- 
tively comprised >90% of numbers taken (Table 3). Two species of odonates 
{Erpetogomphus compositus, Comphus intricatus) were collected on 10-13 
November. Biomass was predominated by C. fluminea, with 5. utico a distant 
second (Table 3). Near-shore habitat supported the largest populations and 
biomasses, with more than 20 times as many individuals and nearly four times 
the biomass as in mid-channel. More than twice as many taxa (17) were 
near-shore as in mid-channel (7). Proportions of total individuals within each 
predominant taxon was, however, about the same for near-shore and mid- 
channel samples (Table 3). 



East 


Mid-channel 


West 


515 
14110 




515 







515 






14114 
22119 


6931265 
43113 


19110 
513 


182190 
96150 



80 CALIFORNIA FISH AND CAME 

TABLE 2. Mean ( 11 Standard Error) Number per Square Meter of Macroinvertebrates 
Collected at East Bank, Mid-Channel, and West Bank Sites in the Earthen Coachella Ca- 
nal, 23-24 October 1980. 

Site 

Invertebrate 
Ephemeroptera 

Baetis sp 

Baetiae, undet. genus 

Odonata 

Hetaerina americana 

Hyponeura lugens 

Trichoptera 

Smicridea utico 

Nectopysche sp 

Lepidoptera 

Parargyractis confusalis 71 5 

Diptera 

Chironomidae 804 1 318 

Chrysops sp 

Non-insecta 

Turbellaria 5 1 5 

Nematoda 

Oligochaeta (Aelosoma sp., Chaetogaster sp.) 6271553 

Ostracoda 

Hydracarina 67131 

Physidae, undet. genus 515 

Corbicula fluminea 10331645 

Number of samples 9 

Overall mean 3305 1 1133 

Total number of taxa 12 

TABLE 3. Mean (H Standard Error) Number and Biomass (mg dry wt) per Square Me- 
ter, and Percentage (in Parentheses) of Total of Predominant Macroinvertebrates Collect- 
ed at Bank Sites (East and West Combined) Compared with Mid-Channel Sites in the 
Earthen Coachella Canal, 23-24 October 1980. 

Site 



48138 


4471325 





14114 





5±5 





112194 


514 


6581454 





616 





24115 





616 


76133 


245711733 


9 


9 


158 1 56 


4050 1 2636 


7 


15 



Invertebrate 




Bank 


Mid-channel 


Trichoptera 








Smicridea utico 


Number 


440 1 150(12) 


19 1 10(12) 




Biomass 


63 1 15(<1) 


2 1 1(<1) 


Diptera 








Chironomidae 


Number 


625 1 252(17) 


45 1 38(28) 




Biomass 


1315(<1) 


1 1 1(<1) 


Non-insecta 








Oligochaeta 








(Aelosoma sp., Chaetogaster sp.) 


Number 


642 1 346(17) 


5 1 5(3) 




Biomass 


45 124(<1) 


<1 10.3(<1) 


Corbicula fluminea 


Number 


1745 1 912(47) 
7460 1 4440(98) 


74 1 33(47) 




Biomass 


20101 1100(99 + ) 


Other Taxa 


Number 


226 193(6) 


15 18(9) 




Biomass 


44 1 18(<1) 


1 1 1(<1) 


Overall Mean 


Number 


3678 1 1394 
7625 1 4205 


158 1 56 




Biomass 


2015 1 1101 


Total Number of Taxa 




17 
18 


7 


Number of Samples 




9 



BENTHIC INVERTEBRATES OF COACHELLA CANAL 



81 



Distribution of total organisms and biomass among stations (Table 4) ap- 
peared related to substrate (Table 1 ) since highest numbers and biomass were 
in habitats containing particulate organics. Greatest density occurred at Station 
1 (west bank) where juvenile clams (shell <4 mm) predominated. Greatest 
biomass was at Station 8 (west bank) where large clams (shells >l-2 cm) 
averaged 1,277/m^ in three replicate samples. Station 8 (west bank) had the 
lowest water velocity and silt/organic substrate, and supported two distinct 
size-classes of clams, the smaller with mean individual dry weight of 0.01 mg, 
and the larger with dry weights of 10-550 mg. 

TABLE 4. Total Number per Square Meter and Biomass (mg dry wt in parentheses) of 

Macroinvertebrates Collected at 27 Sites (East Bank, Mid-Channel, and West Bank at 

Each of Nine Stations) in the Earthen Coachella Canal, 23-24 October 1980. 



Site 



East Bank 


Mid-Channel 


West Bank 


4692 (185) 





(0) 


24,282 


(487) 


9643 (586) 


430 


(10) 


1205 


(51) 


43 (1) 





(0) 


215 


(2) 


6974 (6117) 





(0) 





(0) 


4649 (234) 


344 


(7) 


1077 


(63) 


1506 (23,724) 





(0) 


344 


(4) 


1765 (104) 


258 


(8191) 


732 


(66) 


86 (1) 


172 


(3014) 


7306 


(66,103) 


387 (38,319) 


215 


(6893) 


1291 


(49) 


3305 (7677) 


158 


(2013) 


4050 


(7425) 


±1133 ±4619 


±56 


±1101 


±2636 


±7335 



Station 

1 

2 

3 

4 

5 

6 

7 

8 

9 

Mean (±1 Standard Error) per Station. 



Oligochaetes were abundant near both shores at Stations 1, 2, and 8, and 
chironomids near shore at most stations. Caddisfly larvae were most abundant 
at Stations 1, 2, 5, and 7, along the east bank where gravel substrates were 
present (Table 1 ) . Mean individual dry weights of these organisms were far less 
than that of clams, which largely explains the predominance of clam biomass. 

The remaining taxa comprised a small numerical and biomass proportion of 
the fauna and had no obvious distributional patterns relative to substrate; they 
were notably more abundant near shore than in mid-channel (Table 3). 

Concrete surfaces exposed upon de-watering were densely populated by 
lepidopteran larvae, P. confusalis, and hydropsychid caddisflies, 5. utico. The 
lepidopteran was unexpected since it was rare in quantitative samples (Table 2), 
yet densities were estimated at 1,500/m^. These organisms are scrapers and 
shredders (Merritt and Cummins 1978), and must have been associated with 
microalgae films on concrete surfaces. The caddisfly, which feeds on drifting 
materials caught in specially-constructed nets, was even more abundant; 
estimated densities were at least 25,000/ m^ and biomass was nearly 2,500 
mg/m^ 

Compared with most lotic systems the invertebrate fauna of the earthen 
Coachella Canal was depauperate in terms of taxa represented and numbers of 
individuals. For example, Merritt and Cummins (1978) reported densities of 
chironomids >50,000/m^ as not unusual in lotic habitats, yet <2,300/m^ were 
in quantitative canal samples. The unfavorable environment afforded by shifting 
sand bottom undoubtedly explains part of the scarcity of organisms (Hynes 
1970). Additional taxa could have been associated with beds of aquatic macro- 



2—76875 



82 CALIFORNIA FISH AND CAME 

phytes; however, qualitative sampling upon de-watering added only two taxa 
(the odonates) not previously collected. Seasons and organisnn life histories 
have significant influences on organisnn abundance and biomass (Rosenberg 
1979) since population numbers are high (mean individual weights are small) 
early in the life of a given cohort. In these contexts data presented here must 
be considered point estimates that may have little relation to mean annual 
standing crops. 

Predominant organisms in the canal were either filter feeders (Asiatic clam, 
many chironomids, the dominant caddisfly), or sediment-detritus ingesters 
(Oligochaeta), while others include predators (Turbellaria, Hydracarina, Heta- 
erina, Hyponeura) and collector-gatherers (Baetidae, Nectopsyche, Chrysops). 
Organisms which rely on a scraping-type habitat (e.g., the snail) were nearly 
absent, or were highly localized in distribution ( P. confusalis) . This suggests that 
during autumn production of attached microalgae was low on natural substrates 
(sand), and local stands on stable substrates such as concrete were inadequate 
to support large populations of dependent invertebrates. 

It is notable that mayflies, typically in high population densities, were poorly 
represented in the canal fauna, and that aquatic beetles, which inhabit an ex- 
ceedingly broad spectrum of habitats, were not found. Seasonal effects may be 
important, or possibly the shifting sand substrate largely excluded these taxa. 
Certainly the most successful organisms were those which lived within sub- 
strates, or which were associated with locally stable substrates (5. utico). 

Since biomass in the canal was predominated by filter-feeding organisms (C 
fluminea and 5. utico), which rely upon zooplankton, phytoplankton, and fine 
organic detritus as food, it is relevant to ask where these foods are derived. Three 
potential sources seem likely: i ) in water from the All American Canal; ii ) aeolian 
particulate materials; and iii) autochthonous production by plants and animals. 
If the first were the case, one would anticipate greater densities and biomass of 
filter feeders upstream near the source of water. This did not occur (Table 4). 
A choice cannot be made between the other alternatives, but a combination of 
those two food sources seems likely. 

CONCLUSIONS 
The earthen Coachella Canal supported a depauperate invertebrate fauna. 
Based upon our observations of stable concrete structures, we expect that 
Cladophora and other periphyton will be highly productive on these substrates 
in the new canal section and will support high secondary production of associat- 
ed grazers and filter-feeders. Burrowers will be habitat-limited until substrate 
accumulates through blow-in from the surrounding dune fields. Water clarity 
should be enhanced by the virtual elimination of bank erosion and this should 
have a positive effect on primary and secondary production. This new canal will 
lack cover such as bank holes and vegetation which provide habitat diversity. 
Too, concrete canals can be effectively cleaned and this disturbance could 
substantially reduce the system's productivity. 

LITERATURE CITED 

Bianchi, I., A. Freddi, A. Cirod, and M, Marian. 1 978. Faunistic considerations and population dynamics of mollusks 
living in irrigation canals in Lombardy. Boll. Pesca Piscic. Idrobiol., 30(2) : 177-206. 

Eng, L. L. 1975. Biological studies of the Delta-Mendota Canal, Central Valley Project, California, II. Final Report, 
U.S. Bureau of Reclamation, Sacramento, CA. 178 p. 



BENTHIC INVERTEBRATES OF COACHELLA CANAL 83 

Hynes, H. B. N. 1970. The ecology of running waters. University of Toronto Press, Toronto, Ontario. 555 p. 

Jaeger, E. C. 1957. The North American deserts. Stanford University Press, Stanford, CA. 308 p. 

Merritt, R. W., and K. W. Cummins. 1978. An introduction to the aquatic insects of North America. Kendall/Hunt 
Publishing Co., Dubuque, lA. 441 p. 

Prokopovich, N. P. 1968. Organic life in the Delta-Mendota Canal, Central Valley Project, California. Progress 
Report, U.S. Bureau of Reclamation, Sacramento, CA. 126 p. 

Rosenberg, D. M. (ed.). 1979. Freshyk^ater benthic invertebrate life histories: current research and future needs. 
Can., Fish. Res. Bd., J. 36(3) : 289-345. 

Schutz, L. 1969. Ecological investigations on the benthic fauna in the Baltic Canal, III. Autecology of vagile and 
hemisessile species on piles overgrown with vegetation and animals: macrofauna. Int. Rev. Gesamten Hy- 
drobiol., 54(4) : 553-592. 

St. Amant, J., R. Hulquist, C. Marshall, and A. Pickard. 1974. Fisheries section including information on fishery 
resources of the Coachella Canal study area, in Calif. Department of Fish and Game. Inventory of the fish 
and wildlife resources, recreational consumptive use, and habitat in and adjacent to the upper 49 miles and 
ponded areas of the Coachella Canal. Report to the U.S. Bureau of Reclamation. 

Winberg, G. G. 1971. Methods for the estimation of production of aquatic animals. Academic Press, New York, 

NY 175 p. 

Young, M. R. 1975. The life cycles of six species of freshwater molluscs in the Worchester-Birmingham Canal. 
Malacol. Soc. London., Proc. 41 (6) : 533-548. 



84 CALIFORNIA FISH AND CAME 

Calif. Fish and Came 69 ( 2 ) : 84-88 1 983 

OSTEOPHAGIA AND ANTLER BREAKAGE AMONG 

ROOSEVELT ELK 

R. TERRY BOWYER ' 

School of Natural Resources 

Humboldt State University 

Areata, California 95521 

Quantified observations of bone and antler chewing by Roosevelt elk, Cervus 
elaphus rooseveiti, were made on Gold Bluffs Beach, Prairie Creek Redwoods State 
Park, Humboldt County, California during 1973. Bulls were observed chewing bones 
and antlers in June and July, and cows during June through August. Seventeen elk 
antlers were measured and sampled for calcium and phosphorus content. Significant 
correlations were found between antler size and both phosphorus content and the 
calcium:phosphorus ratio. It was suggested osteophagia was in response to calcium 
and phosphorus deficiencies in forage plants, and that such inadequacies were 
related to antler breakage in bulls. Differences in the mineral intake between domi- 
nant and subordinate individuals were related to elk dominance hierarchies, and are 
discussed in terms of their adaptive significance. 

INTRODUCTION 

The consumption of bones and antlers by free-ranging ungulates may be 
widespread. Osteophagia has been reported for several cervids (Murie 1935, 
Flerov 1952, Banfield 1954, Harper et al. 1967, Dansie 1968, Prior 1968, Kraus- 
man and Bissonette 1977), and the consumption of bird eggs (Palmer 1926) as 
well as other occasional carnivory by ungulates (Severinghaus 1967, Skoog 1968, 
Wormell 1969, Stone and Palmater 1970) may be similar to osteophagia. 

The reason generally offered to explain bone and antler chewing is sup- 
plementation of a calcium or phosphorus deficient diet. However, with the 
exception of Langman (1978), little quantitative information exists on the miner- 
als obtained by osteophagia, or the frequency with which this behavior occurs. 
This paper provides a quantified description of osteophagia for Roosevelt elk, 
Cervus elaphus rooseveiti, and examines the relationship between osteophagia 
and antler breakage among bulls. 

STUDY AREA AND METHODS 

This study was conducted on the Cold Bluffs Beach portion of Prairie Creek 
Redwoods State Park, Humboldt County, California. The study area is com- 
prised largely of coastal prairie separated from nearby redwood. Sequoia seper- 
vlrens, forest by precipitous sandstone cliffs. Red alder, Ainus rubra, groves 
surround numerous creeks in the 4-km^ area. The climate is mild, but rainfall 
commonly exceeds 200 cm per year. More complete descriptions of the Gold 
Bluffs Beach climate and vegetation are available elsewhere ( Harper et al. 1 967, 
Franklin, Mossman and Dole 1975, Bowyer 1976). Elk were observed for over 
700h between 12 November 1972 and 28 November 1973. Behavioral data were 
recorded using an all-occurrences log (Altmann 1974). 

The circumference of the main beam for each of 17 antlers was measured 
directly above the corona. The total length of each antler was measured along 
the main beam from the corona to the tip of the last tine (royal or sur-royal), 
and the number of tines recorded. An index of antler size was obtained by 

' Mr. Bowyer's current address is: Center of Environmental Sciences, Unity College, Unity, Maine 04988. Accepted 
for publication November 1981. 



OSTEOPHACI A AMONG ROOSEVELT ELK 85 

multiplying antler length by antler circumference and dividing by 1000. This 
measurement was used rather than antler weight or density because some 
antlers were attached to the skulls of museum specimens. Samples for chemical 
analysis were obtained by drilling a small hole through the main antler beam at 
the mid-point of its length. Plant and soil samples for chemical analyses were 
collected at random from Cold Bluffs Beach in July 1973. Chemical analyses 
were performed by the Department of Soils, Water, and Engineering of the 
University of Arizona. Antler and plant samples were subjected to a perchloric 
acid digestion for calcium and phosphorus determinations (Horwitz 1975). For 
the soil sample, calcium was determined by the soluable plus exchangeable 
method, while phosphorus was determined using the saturated carbon dioxide 
extraction method (Horwitz 1975). 

RESULTS AND DISCUSSION 

Bulls were observed chewing bones or antlers on six occasions in June and 
July, and a cow did so once during August. Osteophagia was observed among 
50% of 10 bulls and 5% of 20 cows which comprised the Cold Bluffs Beach 
herd. Other researchers observed Roosevelt elk cows chewing bones on eight 
occasions in June and July (Severy, Kitchen, and Mandel, Humboldt State Univ., 
pers. commun.) and once during December (Harper et al. 1967). A yearling 
male was observed chewing bone in late April (Mandel, Humboldt State Univ., 
pers. commun.). It appeared all bones and antlers chewed were from elk. Those 
bones recognized included a scapula, rib, vertebra, lower jaw, and cannon bone. 
Bones and antlers were never completely consumed by elk. Three bones and 
an antler examined after elk had chewed them all showed areas where small 
splinters and chips had been broken away and, presumably, ingested. Elk 
chewed bones and antlers with their premolars and molars and often turned the 
object in their mouth while chewing. A cow once temporarily lodged a vertebra 
in her mouth. The mean length of time elk engaged in osteophagia was 10 min 
(SD = 5.8 min, range = 5-20 min, N = 7). 

Agonistic encounters between bulls over the possession of bones and cast 
antlers were observed on five occasions during June, and accounted for 16% 
of observed bull aggression during that month. Aggression over bones or antlers 
was not observed in other months. \ 

Following the 1972 rut, 5 of 10 bulls sustained breaks of the main antler beam. 
Severe antler breakage occurred among bulls with small or medium sized ant- 
lers, but was not observed in large-antlered males. However, after the 1973 
mating season, there were no breaks of the main beam; antler breakage was 
restricted to tines. Although the sample was small, a highly significant difference 
occurred in the number of bulls with breaks of the main antler beam between 
1972 and 1973 (X^ = 6.66, P<0.01, 1 d.f.). Logsden (cited in McCullough 1969) 
noted that elk from this area showed little or no antler breakage in 1964. Variabil- 
ity among years in which antlers were broken and the occurrence of osteophagia 
by bulls just prior to velvet shedding in August, raise the possibility that calcium 
and phosphorus obtained by this behavior may be related to antler size and 
strength. 

Significant positive correlations were found between antler length and antler 
basal circumference (r^ = 0.43, P<0.01, 16 d.f.) and between the number of 



86 CALIFORNIA FISH AND CAME 

antler tines and antler length (r^ = 0.99, P< 0.001, 16 d.f.) (Table 1). The 
correlation between antler basal circumference and the number of antler tines 
was not significant (r^ = 0.01, P>0.99, 16 d.f.). Since most of the variation in 
the number of antler tines was explained by antler length, and number of tines 
was significantly correlated with the composite variable antler size (r^ = 0.39, 
P<0.05, 16 d.f.), number of tines was eliminated from further analyses. 

TABLE 1. Measurements and Mineral Composition of 17 Roosevelt Elk Antlers 

Mean SD Range 

Length 
(cm) %.5 11.2 77.6-121.2 

Basal circumference 

(cm) 21.1 2.4 16.5-25.4 

Tines 

(no.) 5.4 0.9 4-7 

Calcium content 

(%) 19.01 3.02 16.63-30.19 

Phosphorus content 

(%) 7.00 0.87 5.51-8.95 

Calcium: phosphorus 

ratio 2.7:1 0.4:1 2.3:1-3.3:1 

A significant positive correlation was found between antler size and phospho- 
rus content (r^ = 0.26, P<0.05, 16 d.f.), but there was no correlation between 
antler size and calcium content (r^ = 0.01, P>0.99, 16 d.f.). 

The ratio between calcium and phosphorus, rather than the amount of phos- 
phorus per se, may be the critical factor in determining antler size and strength. 
Unfortunately, no optimum calcium:phosphorus ratio has been established for 
elk antlers. The four largest elk antlers (length X = 1 10.7 cm, SD == 4.5 cm, range 
= 100.5-121.2 cm; cjrcumference X = 24.5, SD = 4.3 cm, range = 23.5-25.4 
cm; number of tines X = 6.5, SD = 0.5, range = 6-7) were assumed to be the 
strongest since main beam breakage did not occur among large-antlered bulls. 
These four antlers approximated a calciumiphosphorus ratio of 2.5:1. This value 
was assumed to be favorable for antler growth and strength, and all other ratios 
were expressed relative to it. When antler size was regressed against the absolute 
value of the difference of the calcium:phosphorus ratio of 2.5:1, the inverse 
correlation was significant (r^ = 0.26, P<0.05, 16 d.f.), but explained no more 
of the variation than did phosphorus content alone. However, antlers from 
which the mineral samples were obtained came from specimens collected from 
1957-1973, and some variation may have resulted from differences in mineral 
availability between years. 

Calcium and phosphorus contents of soil from a prairie area on Gold Bluffs 
Beach were < 0.001% and 0.103%, respectively. Prairie wedge grass, Spheno- 
pholis obtusata, had a calcium content of 0.729% and a phosphorus content of 
0.1 03%. The calcium content of red alder leaves was 0.598% and its phosphorus 
content was 0.174% . The calcium:phosphorus ratio for prairie wedge grass and 
red alder was 7.1:1 and 2.9:1, respectively. The phosphorus content of prairie 
wedge grass was identical to the amount of this mineral available in the soil, 
suggesting the possibility of low phosphorus availability in some forage species. 

Care should be exercised in interpreting these data. The true digestibility of 
phosphorus is quite high in domestic ruminants while a considerably smaller 



OSTEOPHAGIA AMONG ROOSEVELT ELK 87 

portion of calcium is assimilated (Church 1971 ). For instance, a broad range of 
calcium:phosphorus values (1:1 to 7:1) are adequate for growth in domestic 
cattle and these rations all result in approximately a 2:1 ratio being deposited in 
bones (Maynard and Loosli 1969). Data relating mineral intake to the final 
chemical composition of elk antlers are unavailable. Nonetheless, the possibility 
exists that phosphorus or the proper calcium:phosphorus ratio may be related 
to antler size and strength, and that elk may supplement their diet by chewing 
bones and antlers. Calcium:phosphorus deficiencies in livestock typically are 
corrected by feeding bone meal (Maynard and Loosli 1969). 

McCullough (1969) presented the only other information concerning the 
mineral composition of Roosevelt elk antlers. He found a mean calcium:phos- 
phorus ratio of 1 .9:1 for 5 antler samples collected from Prairie Creek Redwoods 
State Parkin 1964. Similarly, the mean ratio for lOtuleelk, C. e. nannodes, antlers 
from Owens Valley, California was 1 .9:1 and 5 antlers from the Tupman Reserve 
in California yielded a mean ratio of 2.0:1 (McCullough 1969). McCullough 
(1969) suggested that tule elk antlers were predisposed to breakage by low 
phosphorus levels available in forage, and noted that those elk herds with the 
highest proportion of phosphorus to calcium in their antlers seemed less prone 
to antler breakage. The significant correlation between antler size and phospho- 
rus content for Roosevelt elk supports this hypothesis. Moreover, phosphorus is 
often in limited supply on western ranges (Stoddart, Smith and Box 1975). 

An inadequate supply of either calcium or phosphorus in an animal's diet may 
limit the nutritive value of both minerals ( Maynard and Loosli 1 969 ) . It is unclear 
whether phosphorus or the calcium:phosphorus ratio is more important in deter- 
mining antler size and strength. X 

Roosevelt elk bulls exhibited a linear dominance hierarchy (Bowyer 1976). 
High-ranking males of Cervos e/ap/jt/s typically have larger antlers than subordi- 
nates, and antler size may be important in the establishment of dominance and 
ultimately influence breeding success (McCullough 1969, Lincoln 1972, Topinski 
1974, Bowyer 1976, Clutton-Brock et al. 1979). All agonistic interactions 
between bulls over possession of bones and cast antlers resulted in subordinates 
relinquishing these objects or being driven away from them. Minerals obtained 
by this behavior may be important in antler size and strength and perhaps 
reproductive success. 

Ruminants have high calcium requirements during lactation and phosphorus 
is needed for the proper growth of young (Maynard and Loosli 1969, Church 
1 971 ) . Elk cows were nursing calves during June and July when bone and antler 
chewing was most common, suggesting osteophagia may supplement minerals 
needed for lactation. 

ACKNOWLEDGMENTS 
I would like to thank the personnel of Prairie Creek Redwoods State Park for 
their help and friendship during my stay at Gold Bluffs Beach. Humboldt State 
University, Prairie Creek Redwoods State Park, and Eureka High School gra- 
ciously contributed elk antlers from their collections. I am indebted to T. Adams, 
R. Botzler, D. Cahill, R. Mandel and M. Phillips for making arrangements for the 
antler sampling and measuring. D.W. Kitchen, D.R. McCullough, K.O. Fulgham, 
J. Wehausen, M. Collopy, V. Bleich, and Y. McCullough provided assistance in 
preparing this manuscript. 



88 CALIFORNIA FISH AND CAME 

Literature Cited 

Altmann, J. 1974. Observational study of behaviour: sampling methods. Behaviour, 49: 227-267. 

Banfield, A.W.F. 1954. Preliminary investigation of the barren ground caribou. Canadian Wildl. Serv., Wildl. Mgmt. 

Bull., Ser. 1 nos. 10A & 10B. 79 & 112 p. 
Bowyer, R.T. 1976. Social behavior of Roosevelt elk during rut. Unpubl. M.S. thesis, Humboldt State Univ., Areata, 

122 p. 
Church, D.C. 1971. Digestive physiology and nutrition of ruminants. Nutrition, Vol. 2. DC. Church and Oregon 

State Univ. Book Stores, Inc., Corvallis, 801 p. 
Clutton-Brock, T.H., S.D. Albon, R.M. Gibson, and F. E. Cuiness. 1979. The logical stag: adaptive aspects of fighting 

in red deer (Cervus elaphus L.). Anim. Behav., 27: 211-225. 

Dansie, W. 1968. Muntjac pecularities. Deer J. Brit. Deer Soc, 1: 181. 

Flerov, C.C. 1952. Musk deer and deer. Fauna of USSR, Mammals. Vol. 1 (New Series). Acad. Sci. USSR. Moscow 
and Leningrad. TransL, 1960. Natl. Sci. Foundation, and the Smithsonian Inst. Washington, D.C. 275 p. 

Franklin, W.L., A.S. Mossman, and M. Dole. 1975. Social organization and home range of Roosevelt elk. ). Mamm., 

56: 102-118. 
Harper, J.A., J.H, Harn, W.W. Bentley, and C.F. Yocom. 1967. The status and ecology of the Roosevelt elk in 

California. Wildl. Monogr., 16: 1-49. 
Horwitz, W. 1 975. Official methods of analysis of the Association of Official Analytical Chemists. 1 2th Edition, 1 094 

P- 
Krausman, P.R., and J. A. Bissonette. 1977. Bone chewing behavior of desert mule deer. Southwest Nat., 22: 

149-150. 
Langman, V.A. 1978. Giraffe pica behavior and pathology as indicators of nutritional stress. ). Wildl. Manage., 42: 

141-147. 
Lincoln, C.A. 1972. The rote of antlers in the behavior of red deer. J. Exp. Zool. 182: 233-250. 
Maynard, L.A., and J.K. Loosli. 1969. Animal nutrition. McGraw-Hill, New York, 613 p. 
McCullough, D.R. 1969. The tule elk: its history, ecology, and behavior. Univ. Calif. Publ. Zool., 88: 1-209. 
Murie, O.). 1935. Alaskan-Yukon caribou. N. Amer. Fauna No. 54, U.S. Dept. Agric, 93 p. 
Palmer, L.J. 1926. Progress of reindeer grazing investigations in Alaska. U.S. Dept. Agric. Bull., 1423, 37 p. 
Prior, R. 1968. The roe deer of Cranborne Chase, an ecological survey. Oxford Univ. Press, London, 224 p. 
Severinghaus, C.W. 1967. Fishy deer. New York State Conservationist, 22: 40. 
Skoog, R. 1968. Ecology of the caribou [Rangiferlarandus grantf) in Alaska. Unpubl. dissertation. Univ. California, 

Berkeley, 699 p. 
Stoddart, L.A., A.D. Smith, and T.W. Box. 1975. Range management. McGraw-Hill, New York, 480 p. 
Stone, W.B., and J.R. Palmateer. 1970. A bird ingested by a white-tailed deer. New York Fish and Game |., 17: 

3. 
Topinski, P. 1974. The role of antlers in establishment of the red deer herd hierarchy. Acta Theriol., 19: 509-514. 
Wormell, P. 1969. Red deer (Cervus elaphus) as a predator on Manx Shearwater (Procellaria puffins). Deer J. 

Brit. Deer Soc, 1: 289. 



CRUNION AND SILVERSIDE EMBRYO SURVIVAL 89 



Calif. Fish and Came 69 ( 2 ) : 89-96 1 983 

CONCURRENT MEASUREMENT OF INTERTIDAL 

ENVIRONMENTAL VARIABLES AND EMBRYO SURVIVAL 

FOR THE CALIFORNIA CRUNION, LEURESTHES 

TENUIS, AND ATLANTIC SILVERSIDE, MENIDIA 

MENIDIA (PISCES: ATHERINIDAE) ^ 

D.P. MIDDAUCH 

U.S. Environmental Protection Agency 

Environmental Research Laboratory 

Gulf Breeze, Florida 32561 

H.W. KOHL and L.E. BURNETT 

University of San Diego 

Department of Biology 

Alcala Park 

San Diego, California 92110 

Concurrent daily measurements of environmental variables and embryo survival 
were made for two atherinid fishes: the California grunion, Leuresthes tenuis, ob- 
served at Blacks Beach, La )olla, California; and the Atlantic silverside, Menidia 
menidia, observed at the Point of Pines, Edisto Island, South Carolina. Measurements 
were made during April 1980. 

Both species spawned in the upper intertidal zone on high tides. L. tenuis eggs 
were deposited approximately 4 cm below the beach surface during nighttime. 
Subsequent sand deposition buried embryos to a depth of approximately 8 cm where 
they were protected from thermal and desiccation stresses. Daily survival of incubat- 
ing embryos averaged 97%. M. menidia utilized three spawning substrates: (i) aban- 
doned crab burrows, (ii) detrital mats, and (iii) the stems and primary leaves of 
cordgrass, Spartina alterniflora. These substrates provided embryos with varying 
degrees of protection from thermal and desiccation stresses. Daily survival of em- 
bryos located 15 cm deep in abandoned crab burrows averaged 88%. Survival was 
less, 76%, at the entrance. Daily survival averaged 94% at the surface of detrital mats 
and at the axis of stems and primary leaves of cordgrass. Survival was lower at other 
locations on these substrates. 

INTRODUCTION 

The California grunion, Leuresthes tenuis, and the Atlantic silverside, Menidia 
menidia, are rhythmic spawners that deposit their eggs in the upper intertidal 
zone (Thompson and Thompson 1919, Middaugh 1981 ). The California grunion 
spawns in a sand substrate at the approximate time of new and full moons during 
February through August (Clark 1925, Walker 1952). Spawning runs occur at 
night and are timed just after the highest high tides during each semilunar period; 
subsequent high tides and wave action result in deposition of sand over the 
incubating embryos (Thompson and Thompson 1919, Moffatt and Thomson 
1978). Approximately 2 weeks after deposition, developed embryos are washed 
out of the sand by the next series of high tides of the same or greater height 
(Shepard and LaFond 1940). The buried embryos are protected from thermal 
stress and remain relatively moist even though they usually are not inundated 
for a week or more during incubation (Thompson and Thompson 1919, Walker 
1949). 

' Accepted for publication December 1981. Contribution No. 221 of The Environmental Research Laboratory, Gulf 
Breeze. 



90 CALIFORNIA FISH AND CAME 

In contrast, the Atlantic silverside deposits eggs on several intertidal substrates 
including: (1) abandoned crab burrows along eroding intertidal scarps; (ii) 
detrital mats; and (iii) the primary leaves and stems of cordgrass plants, Spartina 
alterniflora. Spawning runs occur during daytime high tides. Eggs are deposited 
at intertidal elevations where they are usually inundated daily during high tide 
(Middaugh, Scott and Dean 1981 ). As with L. tenuis, maximum intensity spawn- 
ing runs of M. menidia occur every 2 weeks at the approximate time of new and 
full moons. A high tide-sunrise cue has been suggested as the synchronizer for 
spawning in M. menidia (Middaugh 1981). 

Similarities in the reproductive periodicity of these atherinids, and differences 
in the substrates utilized for egg deposition, prompted a study of intertidal 
environmental variables and embryo survival of L. tenuis and M. menidia. During 
April 1980, daily observations of L. tenuis were made at Blacks Beach, La Jolla, 
California and similar observations of M. menidia were made at the Point of 
Pines, North Edisto River estuary in South Carolina. 

MATERIALS AND METHODS 
Study Sites 
Blacks Beach, La Jolla, California (lat. 32°52'37", long. n7°15'0") is located 
at the base of 50-m high cliffs, about 1 km northwest of the Scripps Institution 
of Oceanography pier. During the highest-high tides in April 1 980, only a narrow 
section of beach, approximately 2.5 m above mean low water (MLW), was 
available as a spawning substrate for L. tenuis. The Point of Pines, North Edisto 
River estuary (lat. 32°35'12", long 80°13'48") is located on the northeastern end 
of Edisto Island, South Carolina. Three substrates utilized for spawning by M. 
menidia, abandoned crab burrows, detrital mats, and cordgrass, S. alterniflora, 
all occur along a 1 00-m section of shoreline at an elevation of approximately 1 .8 
m above MLW. 

Environmental Measurements 

Measurements of sand deposition and erosion were made at Blacks Beach. 
A wooden stake marked at 1-cm intervals was driven into the substrate at the 
location where females were observed depositing eggs on the nighttime high tide 
of 1 7 April 1 980. Daily measurements were taken between 1 1 00 and 1 300 Pacific 
Standard Time (PST) to establish the pattern of sand deposition and erosion 
from 18 to 30 April. 

Substrate temperatures were measured at the surface of the beach (0 to 2 cm 
deep) and at the estimated depth of incubating embryos each day between 1 100 
and 1300 PST. Two replicate measurements were made at 3 to 5 minute intervals 
with a YSI telethermometer (mention of trade names does not imply endorse- 
ment by the U.S. Environmental Protection Agency or the University of San 
Diego) and Model 401 probe. 

Percentage moisture (g water/kg sand) at the beach surface and depth of 
incubating embryos was determined by taking a 2.5 cm diameter core, extruding 
the sample from the coring tube and quickily placing 2.0 cm sections in air tight 
plastic bags. Samples were taken to the laboratory, weighed, dried for 24 hours 
at 90° C and reweighed. 



CRUNION AND SILVERSIDE EMBRYO SURVIVAL 91 

A Bailey Instruments Model BAT-4 Laboratory Thermometer with a MT-29/1 
microprobe was used to measure substrate temperatures at the following loca- 
tions on spawning substrates of M. menidia: (i) abandoned crab burrows at the 
lip of the entrance and on the wall 15 cm below the entrance; (ii) detrital mats 
on the surface and 4 cm below the surface; (ill) Spartina alterniflora, at the axis 
of the stem and primary leaves and 4 cm above it. 

Percentage moisture (g water/kg atmosphere) was measured at the locations 
outlined above (except 4 cm below the surface of detrital mats) with an Atkins 
Model 90023-30 Digital Psychrometer. Replicate measurements of temperature 
and moisture were made at 3- to 5-min intervals between 1 100 and 1300 Eastern 
Standard Time (EST). 

Where appropriate, paired comparison t-tests were used to test for differences 
in environmental variables and embryo survival at each location on respective 
spawning substrates (Sokal and Rohlf 1969). 

Embryo Survival 

One or two pods of L. tenuis embryos were collected daily from 18 to 28 April 
and microscopically classified as viable or nonviable. 

Groups of M. menidia embryos were collected from each substrate location 
from 22 to 28 April. The first 30 embryos from each substrate location, observed 
with a dissecting microscope, were also classified as viable or nonviable. For the 
first few days, eggs of each species were classified as viable or nonviable on the 
basis of similar developmental stages for all individuals. Later, the absence or 
presence of a heart beat was used to determine viability. 

RESULTS 
Sand Deposition 

There was an overall trend of sand deposition from 18 to 28 April at the 
intertidal elevation where L. tenuis eggs were deposited on the night of 17 April. 
We estimated that eggs were deposited approximately 4 cm below the beach 
surface by females (Figure 1). The nighttime high tide on 28 April caused 
moderate erosion (measured on 29 April); many embryos were presumably 
washed out of the substrate. Measurements taken on 30 April indicated that a 
total washout occurred on the nighttime high tide of 29 April when erosion 
reduced the substrate elevation to approximately 11 cm below the developing 
embryos (Figure 1 ). An extensive search between 1100-1300 PST on 29 and 30 
April failed to yield embryos from the spawning area of 17 April. 

Substrate Temperatures 

Substrate temperatures where L. tenuis embryos developed were less extreme 
than on the surface (Figure 2a). The maximum temperature at the surface was 
40° C; at the depth of embryos, 31° C. During the 12-day incubation period, 
temperatures at the depth of embryos were significantly lower ( P < 0.001 ) than 
at the surface. 

Temperatures in abandoned crab burrows utilized as a spawning substrate by 

M. menidia were very uniform (Figure 2b). The temperature varied only 6°C at 

the burrow entrance during embryo development; and J^C at 15 cm depth. 

During the 7-day incubation period temperatures were significantly lower (P < 

0.05) at the 15 cm depth than at the burrow entrance. Temperatures were less 



92 



CALIFORNIA FISH AND GAME 



uniform in detrital mats (Figure 2c). The range at the surface was 16°C, max- 
imum temperature 40°C. At 4 cm depth, the temperature range was 13°C and 
maximum temperature, 34°C. Surface temperatures and those at 4 cm depth in 
detrital mats were significantly different (P < 0.01 ). The harshest environment 
for embryos was 4 cm above the axis of stems and primary leaves of 5. alterni- 
flora, where a maximum temperature of AVC was measured (Figure Id). Tem- 
peratures measured at the axis of the stem and primary leaves, and 4 cm high 
on 5. alterniflora leaves were not significantly different ( P > 0.05); however, the 
maximum temperature for the former location was only 36°C. 




Figure 1. Egg deposition and subsequent deposition and erosion of sand from Blacks Beach, 
California. Arrow indicates beach surface on 18 April, 1980. 

Percentage Moisture 

The moisture content of the sand where L. tenuis embryos developed ranged 
from 1 to 19% (Figure 2e) . There was no significant difference (P < 0.05) in 
the moisture content at the surface (0 to 2 cm deep) and the depth at which 
embryos developed. 

Atmospheric moisture was uniformly high and similar (P < 0.05) at the en- 
trance and at 15 cm depth in abandoned crab burrows where M. menidia 
embryos occurred (Figure 2f) . At the surface of detrital mats, moisture was 
similar to that measured in abandoned crab burrows (Figure 2g) . No measure- 
ments were made at 4 cm depth in detrital mats; however, embryos were always 
moist at this location and there was no evidence of desiccation. Embryos devel- 



GRUNION AND SILVERSIDE EMBRYO SURVIVAL 



93 



oping at 4 cm above the axis of stems and primary leaves of 5. alterni flora were 
exposed to significantly lower atmospheric moisture (P < 0.001) than those 
lower on the plant (Figure Ih). 




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Figure 2. 



Concurrent daily comparison of environmental variables and embryo survival for the 
California grunion, Leuresthes tenuis, and Atlantic silverside, Menidia menidia. L. tenuis: 

a) beach surface • •, depth of embryos o o; M. menidia: b) burrow entrance, 

• •, 15 cm deep o o,c) detritus surface • ; 4 cm deep, o o, d) primary leaves 

• •, 4 cm high o o ; L tenuis: e) beach surface • •, depth of embryos o o ; M. 

menidia: f) burrow entrance • ; 15 cm deep o o, g) detritus surface • •, h) 

primary leaves • ; 4 cm high o o. L. tenuis, i) buried embryos o o; M. 

menidia: j) burrow entrance m 0, 15 cm deep o o, k) detritus surface « •, 4 cm 

deep o — o, I) primary leaves 0, 4 cm high o o. 

Embryo Survival 
L tenuis ernbryos showed excellent survival during the 12-day incubation 
period, daily X = 97% (Figure 2/). Although wide daily variations occurred, 
there was no significant difference (P < 0.05) in the number of surviving M. 
menidia embryos taken from the entrance or 15 cm depth in abandoned crab 
burrows ( Figure 2j) . During the 7-day incubation period, survival at the entrance 
to burrows averaged 76%; at the 15 cm depth, 88%. The number of surviving 
embryoson the surface of detrital mats was significantly greater (P < 0.05) than 
4 cm deep (Figure 2^), even though temperatures were more rigorous at the 
surface of the mat ( Figure 2c) . Finally, embryos deposited at the base of primary 
leaves of cordgrass showed significantly better survival (P < 0.01 ) than those 
4 cm high (Figure 2/). Very poor survival in daily samples taken from 24 to 28 
April probably resulted from extremely high temperatures on 24 April (Figure 
Id). 



94 CALIFORNIA FISH AND CAME 

DISCUSSION 

The California grunion spawns fronn February through August, with peak 
intensity runs from April to June (Walker 1949, 1952). Shepard and LaFond 
(1940) observed that spawning during April to June ensured against the influ- 
ence of seasonal cut or fill of the spawning substrate since the primary influence 
on sand movement during the period was tidal. Earlier in the year, October to 
February, a combination of physical factors resulted in net loss of sand, whereas 
later, during July to September, there was net accretion of sand on the beach 
adjacent to the Scripps Pier. Timing of spawning runs to coincide with the 
highest high tides or a decreasing tidal series on nights following the highest high 
tides resulted in deposition of sand over embryos developing in a high-energy 
environment. 

During the present study, L. tenuis spawned in the sand of Blacks Beach during 
the nighttime high tide of 1 7 April, part of the decreasing tidal series. Subsequent 
sand deposition buried the embryos to a maximum depth of approximately 8 cm 
prior to washout (Figure 1 ). Deposition of sand provided protection from ther- 
mal and desiccation stresses and predation. Walker (1949) reported that shore 
birds, including marbled godwits, Limosa fedosa, and Hudsonian curlews, 
Numenius phaeopus hudsonicus, actively probed the sand in search of L. tenuis 
embryos. California gulls, Larus californicus, were observed feeding on embryos 
left at the surface by godwits and curlews. It is likely that birds would find pods 
of embryos buried to a depth of 7 to 15 cm (Thompson and Thompson 1919 
and this study) more difficult to locate than ones 3 to 4 cm deep, the approxi- 
mate depth of pods immediately after deposition by females. Recently, Moffatt 
and Thomson (1978) reported that L. tenuis egg pods were buried to a depth 
of 30 cm. At this depth predation would be highly unlikely. Moreover, ambient 
temperatures and the percentage moisture probably would be more uniform, 
and less rigorous, than measured in our study. 

In contrast, M. menidia spawns in a relatively low-energy estuarine environ- 
ment. Spawning runs occur during daytime high tides in the upper intertidal 
zone. Although M. menidia occasionally spawns aerially at the water's edge, 
release of eggs and milt usually occurs underwater. Precise timing of spawning 
to coincide with high tide, when tidal currents are low, probably helped to 
ensure egg fertilization since eggs and milt would remain in close proximity for 
a longer period during slack high tide than at times when current velocities are 
stronger (Middaugh 1981). Recently, Middaugh and Takita (manuscript in 
preparation) learned that 10-min old M. menidia sperm were capable of fertiliz- 
ing 95% of freshly stri^•ped eggs, but aging of sperm for 20 min reduced the 
fertilization rate to only 26%. 

L. tenuis embryos monitored during this study showed excellent survival. 
Substrate temperatures where embryos developed ranged from 19° to 32° C, X 
= 25° C. Thompson and Thompson (1919) measured temperatures from 16 to 
27° C at a depth of 7 to 15 cm below the surface; concurrent surface tempera- 
tures ranged from 1 5 to 36° C. Our data and those of Thompson and Thompson 
(1919) are within the thermal limits for L. tenuis determined in laboratory 
studies. Hubbs (1965) reported successful fertilization at temperatures between 
12 and 32.5° C; however, hatching occurred only between 14.8 and 26.8° C. 



GRUNION AND SILVERSIDE EMBRYO SURVIVAL 95 

Similarly, Ehrlich and Farris (1971) observed that L. tenuis embryos hatched 
when maintained at 1 4.0 to 28.5° C. Optimum hatching, close to 1 00%, occurred 
between 16.0 and 27.0° C, but dropped off rapidly outside this range. Moffatt 
( 1 977 ) reported a thermal tolerance limit of 1 8 to 30° C for embryonic develop- 
ment and 50% hatching in L. tenuis. Infrequent hatching was noted for embryos 
maintained at 14° C. Hatched prolarvae showed decreased total length and 
weight when incubated at temperatures above 25° C. Hubbs ( 1 965 ) pointed out 
that embryos incubated at temperatures above 19° C would be able to hatch on 
the next series of highest tides (approximately 10 to 14 days after they were 
fertilized). During our study, these high tides occurred 1 1 and 12 days after eggs 
were fertilized, i.e., on the nights of 28 and 29 April. No embryo pods were 
found, despite extensive digging, during daytime (1100-1300 PST) on 29 and 30 
April. 

Thompson and Thompson (1919) and Walker (1952) reported that L. tenuis 
embryos remained relatively moist even though they had not been covered by 
high tides for several days. In our study, interstitial water ranged from 1 to 19% 
(10 to 190 g/ kg sand). Sand at the depth of incubating embryos was damp; no 
desiccation was evident. 

Temperatures encountered by developing M. menidia embryos were, in gen- 
eral, within their thermal tolerance range. Critical thermal maxima (CTM) tests 
(Hutchinson 1961 ) conducted with newly fertilized embryos (0-to 1-cell stage) 
indicated at least 96% survival up to 38° C, 66% at 39° C, and no survival at 40° 
C. In tests with embryos in the closure of blastopore stage ( 1 9-h post-fertilization 
at 25° C) and in the onset of circulation stage (48-h post-fertilization at 25° C), 
the CTM was 42° C (Middaugh, unpubl. data). 

M. menidia embryos developing in abandoned crab burrows and detrital mats 
retained their spherical shape; there was no evidence of extreme desiccation. 
However, those located 4 cm above the juncture of stems and primary leaves 
of S. alterniflora did suffer desiccation and, apparently, the effects of thermal 
stress. On 24 April, embroys located 4 cm high on Spartina had been distorted 
to a half sphere by desiccation; one side was dimpled. The cumulative effects 
of thermal stress, a temperature of 41° C was measured on 24 April, and desicca- 
tion resulted in very low survival of embroys sampled on 24 April and subse- 
quent days. 

In summary, reproductive tactics of Leuresthes tenuis and Menidia menidia 
are remarkably similar. Both species spawn intertidally, generally from March 
through July. The fortnightly (lunar) spawning periodicity observed in L tenuis 
(Walker 1949, 1952) apparently has evolved because of the availability of a 
relatively stable spawning substrate during the highest high tides and decreasing 
tidal series shortly after new and full moons (Thompson and Thompson 1919). 
Additionally, deposition and erosion of spawning substrates during April to June 
is influenced primarily by tidal forces; there is not a long term trend of cut and 
fill that occurs during other times of the year (Shepard and LaFond 1940). 

Menidia menidia also shows a fortnightly periodicity for maximum intensity 
spawning runs (Middaugh 1981). However, the coincidence of a high tide at 
the time of sunrise every 2 weeks, at the approximate time of new and full 
moons, apparently cues the observed periodicity. Deposition of eggs in aban- 
doned crab burrows, detrital mats, or on Spartina alterniflora probably occurs 
because these substrates provide protection from thermal stress, desiccation, 
and predation. 



96 ' CALIFORNIA FISH AND CAME 

LITERATURE CITED 

Clark, F.N. 1925. The life history of Leuresthes tenuis, an atherinid fish with tide controlled spawning habits. Calif. 

Fish and Game Comm. Bull., 10:1-51. 
Ehrlich, K.F., and D.A. Farris. 1 971 . Some influences of temperature on the development of the grunion, Leuresthes 

tenuis (Ayres). Calif. Fish Came, 57(1):58-68. 
Hubbs, C. 1965. Developmental temperature tolerance and rates of four southern California fishes, Fundulus 

parvipinnis, Atherinops affinis, Leuresthes tenuis, and Hypsoblennuis sp. Calif. Fish Came, 51 (2) ;1 13-122. 
Hutchinson, V.H. 1961. Critical thermal maxima in salamanders. Physiol. Zool., 2:92-125. 
Middaugh, D.P. 1981. Reproductive ecology and spawning periodicity of the Atlantic silverside, Menidia menidia 

(Pisces:Atherinidae). Copeia, 4:766-776. 
Middaugh, D.P., C.I. Scott, andJ.M. Dean. 1981. Reproductive behavior of the Atlantic silverside. Menidia menidia 

(Pisces:Atherinidae). Environmental Biology of Fishes, 6(%):269-276. 

Moffatt, N.M. 1977. Thermal effects on the survival and development of embryonic grunions Leuresthes sardina 

and L. tenuis Ph.D. Dissertation. University of Arizona, Tucson. 88 p. 
Moffatt, N.M., and D.A. Thomson. 1978. Tidal influence on the evolution of egg size in grunions (Leuresthes, 

Atherinidae). Environmental Biology of Fishes, 3(3):267-273. 
Shepard, F.P., and E.C. LaFond. 1940. Sand movements along the Scripps Institution Pier. Am. J. Sci., 238:272-285. 
Sokal, R.R., and J.F. Rohlf. 1969. Biometry. W.H. Freeman and Co., San Francisco. 776 p. 
Thompson, DA., and J.B. Thompson. 1919. The spawning of the grunion. Calif. Fish Game Comm. Bull., 3:1-29. 
Walker, B.W. 1949. Periodicity of spawning by the grunion, Leuresthes tenuis, an Atherine fish. Dissertation. Univ. 

of Calif., Los Angeles. 166 p. 
. 1952. A guide to the grunion. Calif. Fish Game, 38(3):409-420. 



SPOTFIN SURFPERCH LIFE HISTORY INFORMATION 97 

Calif. Fish and Came 69 ( 2 ): 97-1 04 1 983 

AGE, GROWTH, REPRODUCTIVE CHARACTERISTICS, 
AND SEASONAL DEPTH DISTRIBUTION OF THE SPOTFIN 

SURFPERCH, 
Hyperprosopon anale ^ 

DONALD M. BALTZ 

and 

ELAINE E. KNIGHT 

Department of Wildlife and 

Fisheries Biology 

University of California 

Davis, California 95616 

Life history information, based on an analysis of museum material, on the age, 
growth, reproductive characteristics, and seasonal depth distribution of the spotfin 
surf perch is presented. Females attain mean standard lengths (SL) of 103 mm at age 
one, 116 mm at age two, and 121 mm at age three. Males grow more slowly. All 
females produce their first brood at age one. Brood size varies from 4 to 20. Brood 
size, size of young, and brood wet weight all increase significantly with length of 
female. The regression of brood size on age is significant; moreover, when used with 
length, age contributes to the prediction of brood size by multiple regression. Spotfin 
surfperch occur in offshore waters (depths of 15-64 m) during most of the year but 
in summer months females migrate inshore and give birth in shallow waters. 

INTRODUCTION 

Life history variation within the family Embiotocidae is extensive and involves 
differences in longevity, growth, and reproductive characteristics; however, 
information on several species is very sparse. To fill one such void for an 
uncommon species, the spotfin surfperch, we analyzed several large museum 
samples. DeMartini (1969) summarized information on food habits and feeding 
morphology of the surfperches. The delicate pharyngeal plates, numerous sharp 
teeth, and mouth structure of the spotfin surfperch correlate well with the limited 
information on their diet of small fishes, zooplankton, and benthic crustaceans 
(Cailliet et al. }^77). This species is now known to range from Blanca Bay, Baja 
California to Seal Rock, Oregon ( Miller and Lea 1 972 ) . Other published informa- 
tion includes systematic status (Tarp 1952) and distributional records (Gilbert 
1915; Roedel 1953; Isaacson and Poole 1965; Miller, Gotshall, and Nitsos 1965; 
Wydoski 1969). The purpose of this paper is to report life history information 
on the age, growth, reproductive characteristics, and seasonal depth distribution 
of this species. 

METHODS 
All of the fish examined were from museum collections from several locations 
and years. A large sample, including 92 gravid females (beach seined by W.I. 
Follett and party at San Simeon on 21 July 1948) was loaned by the California 
Academy of Sciences (CAS 25471 ) . Other series, beach seined by B. W. Walker 
and party at San Simeon on 27 June 1949 (W49-161) and on 20 July 1950 
(W50-145), were loaned by the Department of Biology, University of California, 
Los Angeles. An additional 73 specimens trawled in Monterey Bay on 6 August 

' Accepted for publication January 1982. 



98 CALIFORNIA FISH AND CAME 

1971 were borrowed from California State University, San Francisco; and 18 
specimens trawled near the Farallone Islands on 24 February 1971 were bor- 
rowed from the Natural History Museum, Los Angeles County ( LACM 32654-1 ) . 
Four Elkhorn Slough specimens were obtained from the teaching collection at 
the University of California, Davis. All of the specimens examined had been 
preserved in formalin and transferred to alcohol. 

Age and growth rates were estimated from annuli on unregenerated scales. 
Scales from the left pectoral region were read independently by two observers 
on a modified microfiche projector (27.5 X); disputed scales were read by a 
third person. Annuli were considered to be false if they were incomplete or 
comparable in size to the regenerated portions of adjacent scales, and counts 
were accepted only if they were the same on two or more scales. Growth rates 
were estimated by back-calculation (Tesch 1971 ). To facilitate comparison with 
other studies, linear equations for converting standard length (SL) to fork length 
(FL) and total length (TL) were fitted: 

FL mm = 5.20 + 1.10 SL mm, r - 0.99, N = 48 
TL mm = 10.20 + 1.13 SL mm, r = 0.99, N = 48. 
The fecundity of 46 near-term females was determined by counting embryos. 
Using stratified sampling, females were selected to cover the range of sizes 
available; however, females were excluded if their genital aperture indicated that 
they might have aborted young. Females and their young were measured to the 
nearest millimetre standard length. The preserved wet weight of the entire brood 
was determined to the nearest 0.01 g. 

RESULTS 
Age and Grov^th 
Females attained mean lengths of 103, 116, and 121 mm SL at ages one, two, 
and three, respectively. The largest female examined was 128 mm SL. The mean 
SL at age, as determined from the age composition of samples collected during 
the birthing season and by back-calculation, was obtained (Table 1). Back- 
calculation appears to greatly underestimate the length at age of near-term 
females. Most of the 1 -year-old females from the San Simeon 1948 collection 
had not formed an annulus by 21 July. The summer collections we examined 
contained only nine adult males. One-year-old males were 81 mm SL and 
2-year-old males were 83 mm SL. Based on these limited data, it appears that 
males may grow more slowly and perhaps do not live as long as females. 

Brood Characteristics 
The number of young in intact broods ranged from 4 to 14 in the samples we 
examined. All females of age one or older collected during the summer months 
(June-August) carried young or were spent. The smallest 1 -year-old female was 
81 mm SL and had a brood of four. Wydoski ( 1 969 ) reported an unusually large 
female (161 mm SL; 4 yr) with a brood of 20; however, he did not indicate 
whether or not this brood was intact. Simple regression analysis of brood size 
on female SL (Figure 1 ) indicates that larger females produce larger broods (y 
= -13.8 + 0.21 X, r = 0.873, N = 46, P < 0.01 ). Age does contribute signifi- 
cantly to prediction of brood size by multiple regression when used with SL. The 



SPOTFIN SURFPERCH LIFE HISTORY INFORMATION 



99 



multiple regression coefficients were both positive and significant (slope of age: 
1.85, P < 0.001; slope of SL: 0.15, P < 0.001 ). The age-specific regression of 
brood size was significant (y = 3.0 + 4.1 x, r = 0.79, N = 46, P < 0.01 ). Mean 
brood sizes at ages one, two, and three were 7.1, 11.4, and 14, respectively 
(Table 2); only one female of age three had an intact brood. The brood wet 
weight (g) increased with female SL (Figure 2; San Simeon 1948: y = —30.5 + 
0.33x, r = 0.714, N = 29, P < 0.01 ) and accounted for as much as 26% of total 
female weight. 

TABLE 1. Mean Standard Length (mm) at Age of Female Spotfin Surf perch. 



Location 


4 Year 


Age 


N 




Mean SL (± 1 SD) 




OBSERVED LENGTH AT ACE 




1 


2 


3 


San Simeon 


1948 


1 
2 


91 

1 


104.3(3.40) 


122 






1949 


1 
2 
3 


3 

16 
2 


94.3(2.52) 


120.4(3.37) 


127.5(0.71) 




1950 


1 
2 
3 


6 
1 
1 


97.3(2.50) 


115 


125 


Monterey Bay 


1971 


1 
2 
3 


7 
13 

7 


95.3(2.43) 


110.2(1.69) 


118.4(1.90) 


Weighted Mean 




1 
2 
3 


107 
31 
10 


103.0 


116.0 


120.9 


Growth Increment 








103.0 


13.0 


4.9 


BACK-CALCULATED LENGTH AT AGE 


1 


2 


3 


San Simeon 


1948 


1 
2 


8 

1 


85.4(9.35) 
101.3 






San Simeon 


1949 


1 

2 



16 


107.9(3.20) 










3 


2 


97.5(4.17) 


121.5(0.57) 




Monterey Bay 


1971 


1 


6 


76.4(4.72) 










2 


13 


89.5(13.05) 


97.6(1.49) 








3 


5 


78.8(5.52) 


91.3(5.27) 


104.0(4.29) 


Weighted Mean 








92.6 


98.4 


104.0 


Growth Increment 








92.6 


5.8 


5.6 



TABLE 2. Age-Specific Brood Size of Spotfin Surfperch. 

Age 

1 2 

Sample Means 7.1 11.4 

SD 1.51 1.74 

N 36 9 



3 
14 



The size of young produced seems to increase with female size; however, 
since parturition occurs earlier in older than in younger females in some embi- 
otocids these trends may not be valid at parturition (Carlisle, Schott, and Abram- 
son 1960). Mean embryo weight (g) increased significantly with female SL (San 
Simeon 1948: y = -2.95 + 0.33 SL, r = 0.64, N = 29, P < 0.01). Embryo 



100 



CALIFORNIA FISH AND GAME 



length (Figure 3) also increased with female SL (San Sinneon 1948: y = —25.4 
+ 0.51 X, r = 0.633, N = 29, P < 0.01 ). Near-term embryos collected at San 
Simeon averaged 27% of the SL of their female parents in June 1948 and 26% 
in July 1949 (range 18-34%). 



20 



15 - 



UJ 
N 

(/) 

o 
oio 

q: 



y--l3.8+0.2lx 
r-0.873 
N-46 
P<O.OI 




o 


Son Simeon 1948 


A 


1949 


D 


1950 


• 


Elkhorn Slough 


▲ 


Monterey Bay 1971 


 


Oregon 1968 



± 



± 



± 



± 



± 



± 



± 



± 



± 



80 90 100 110 120 130 140 150 160 
FEMALE STANDARD LENGTH 



FIGURE 1 . The regression of brood size on standard length ( mm ) of female spotfin surfperch. The 
Oregon specimen (Wydoski 1969) was not included in the regression. 

Seasonal Depth Distribution 

A review of depth distribution data for spotfin surfperch suggests that they 

occupy offshore waters (15-64 m) during most of the year, but in summer 

months schools composed mostly of females move inshore where the young are 

born between June and August. Trawl surveys in Monterey Bay indicate that 



SPOTFIN SURFPERCH LIFE HISTORY INFORMATION 



^01 



spotfin surfperch are locally abundant during all seasons at survey depths of 15 
to 35 m I Kukowski 1 973; CM. Cailliet, Moss Landing Marine Laboratories, pers. 
commun.); however, catch-per-unit-effort appears to decline between 18 and 
30 m. Future studies should document sex-specific differences in distribution and 
growth rates. 

Recent work (Dorn, Johnson, and Darby 1979) comparing the swimming 
abilities of pregnant and nonpregnant rainbow surfperch, Hypsurus caryi, indi- 
cates that near-term females are unable to achieve the sustained or burst swim- 
ming speeds typical of the species; therefore, they must be at a great 
disadvantage when trying to avoid predators. This is probably true for all near- 
term surfperches, and females of many species move inshore or take refuge in 
turbid bays, eelgrass beds, or other complex habitats where they and their young 
can better avoid predation. The young can grow more rapidly in a warm, 
productive habitat. This tendency helps to explain the skewed adult sex ratios 
seen in many inshore collections of embiotocids; however, the slower growth 
of male spotfin surfperch suggests that they, like some other male embiotocids, 
also suffer higher mortality than females (Warner and Harlan 1982). Thus the 
skewed adult sex ratios observed in spotfin surfperch collections are related to 
sex-specific differences in distribution and/or mortality. 



X 
UJ 

I- 

UJ 

^ 5 

o 
o 
o 
o: 



*-V 




90 fOO 110 120 

FEMALE STANDARD LENGTH 



FIGURE 2. The regressions of preserved brood wet weight (g) on female standard length (mm) 
in two samples of near-term embryos: open circles, solid line, San Simeon 1948 (y = 
-30.5 + 0.33x, r = 0.714, N = 29, P < 0.01); open triangles, dashed line, San 
Simeon 1949 (y = -32.7 + 0.35x, R = 0.971, N = 10, P < 0.01). 



102 



CALIFORNIA FISH AND CAME 



35 



E 30 



o 

>- 
oc 
m 

liJ 25 

z 
< 

UJ 



20 



15 - 




^ 



J- 



± 



90 100 110 120 

FEMALE STANDARD LENGTH 



FIGURE 3. 



The regressions of mean embryo standard length (mm) on female standard length 
(mm) in two samples of near-term embryos: open circles, solid line, San Simeon 1948 
(y = -25.4 -I- 0.51x, r = 0.633, N = 29, P < 0.01 ); open triangles, dashed line, San 
Simeon 1949 (y = -20.8 -f 0.44x, r = 0.978, N = 10, P < 0.01). 



DISCUSSION 

The life history of the spotfin surfperch is best understood in comparison to 
what is known of other embiotocids. Miller and Lea ( 1 972 ) indicated that spotfin 
surfperch attain a maximum size of 152 mm TL; however, a much larger female 
(199 mm TL) was reported by Wydoski (1969). Such large individuals are 



SPOTFIN SURFPERCH LIFE HISTORY INFORMATION 103 

apparently quite rare, and spotfin surfperch are annong the smallest embiotocids 
(Miller and Lea 1972). Generally none of the small species studied, including 
spotfin surfperch, delay first reproduction beyond age one (Hubbs 1921, Wilson 
and Millerman 1969, Hayase and Tanaka 1980). However, under some circum- 
stances resulting in poor growth, tule perch, Hysterocarpus traski, and shiner 
surfperch, Cymatogaster aggregata, may not produce their first brood at age one 
(Cordon 1965, Baltz 1980). The increasing trends in age- and length-specific 
reproductive characteristics, including brood size, size of young, and brood wet 
weight, found in the spotfin surfperch are typical of most embiotocids. Only the 
pink surfperch, Zaiembius rosaceus, does not show a significant increase in 
brood size with female length (Baltz, unpubl. data) and has a mean brood size 
of 3.5 (Goldberg and Ticknor 1977). However, the lack of an increasing length- 
fecundity trend in pink surfperch may be an artifact of capture in deep water 
since fecund females tend to abort their young. Other small embiotocids have 
brood sizes comparable to spotfin surfperch (Abe 1969, Wilson and Millerman 
1969, Hayase and Tanaka 1980); but tule perch, kelp surfperch, Brachyistius 
frenatus, (Baltz, unpubl. data), dwarf surfperch, Micrometrus minimus, and reef 
surfperch, M. aurora, (Hubbs 1921 ) and one Japanese species, Ditrema viridis, 
(Abe 1969, Hayase and Tanaka 1980) greatly exceed the spotfin surfperch in 
length-specific fecundity. 

Other members of the genus IHyperprosopon differ greatly from spotfin surf- 
perch in life history traits. Both the silver surfperch, H. ellipticum, and the 
walleye surfperch, /-/. argenteum, are considerably larger species, maximum 
length 267 and 305 mm TL, respectively (Miller and Lea 1972). They are also 
longer lived and may delay first reproduction. Silver surfperch produce their first 
brood at age two and live for 5 years (Wydoski and Bennett 1973). Walleye 
surfperch populations near the southern end of their range may attain 170 mm 
SL, live for 4 or 5 years, and produce their first brood at age one ( E.E. DeMartini, 
Marine Science Institute, U.C. Santa Barbara, pers. commun.); however, females 
in central California and Oregon attain a larger size (226 mm SL), have higher 
fecundity and may delay reproduction for one or more years (Baltz, unpubl. 
data). Based upon the morphological distinctiveness of the spotfin surfperch 
from other members of the genus, Hubbs, Follett, and Dempster (1979) use the 
scientific name /-fypocriticfithys analis rather than Hyperprosopon anale ( W. I. 
Follett, California Academy of Sciences, pers. commun.). Both life history and 
morphological variation within the genus deserves further attention. 

ACKNOWLEDGMENTS 
We thank M. Bradbury, D. Buth, R. H. Rosenblatt, P. Sonoda and C. Swift for 
assistance in the acquisition of specimens. G. Cailliet, E. DeMartini and C. Swift 
made helpful comments on earlier versions of this paper. 

LITERATURE CITED 

Abe, Y. 1969. Systematics and biology of the two species of embiotocid fishes referred to the genus Ditrema in 
Japan. Japanese Ichthyology, 15(3);105-121. 

Baltz, D. M. 1980. Age-specific reproductive tactics and reproductive effort in the tule perch (Hysterocarpus 
traskf). Ph. D. dissertation. University of California, Davis. 85 p. 

Cailliet, C. M., B. Antrim, D. Ambrose, S. Pace, and M. Stevenson. 1977. Species composition, abundance and 
ecological studies of fishes, larval fishes, and zooplankton in Elkhorn Slough. Pages 216-386 in Nybakken, )., 
G. Cailleit, and W. Broenkow, eds. Ecological and Hydrographic Studies of Elkhorn Slough, Moss Landing 
Harbor and Nearshore Coastal Waters. Moss Landing Marine Laboratories, 464 p. 



104 CALIFORNIA FISH AND GAME 

Carlisle, ). C, ). W. Schott, and N. J. Abramson. 1960. The barred surfperch (Amphisticus argenteus Agassiz) in 
southern California. Calif. Dept. Fish and Game, Fish Bull. (109):1-79. 

DeMartini, E.E. 1969. A correlative study of the ecology and comparative feeding mechanism morphology of the 
Embiotocidae (Surf-fishes) as evidence of the family's adaptive radiation into available ecological niches. 
Wasmann |. of Biol., 27 (2) :1 77-247. 

Dorn, P., L. Johnson, and C. Darby. 1 979. The swimming performance of nine SF>ecies of common California inshore 

fishes. Am. Fish. Soc, Trans., 108:366-372. 
Gilbert, C. H. 1915. Fishes collected by the United States steamer "Albatross" in southern California in 1904. Proc. 

U. S. Nat. Mus., 48:305-380. 
Gordon, C. D. 1965. Aspects of the life history of Cymatogaster aggregate. Thesis, Univ. British Columbia. 90 p. 
Goldberg, S. R. and W. C. Ticknor, Jr. 1977. Reproductive cycle of the pink surfperch, Zaiembius rosaceus 

(Embiotocidae). Fishery Bull., 75(4):882-884. 
Hayase, S. and S. Tanaka. 1980. Growth and reproduction of three species of embiotocid fishes in the Zostera 

marina belt of Odawa Bay. Bull. Japanese Soc. Sci. Fisheries, 46(9); 1089-1096. 
Hubbs, C. L. 1921. The ecology and life history of Amphigonopterus aurora and other viviparous perches of 

California. Biol. Bull., 40(4):181-209. 
Hubbs, C. L., W. I. Follett, and L. J. Dempster. 1979. List of the fishes of California. Occas. Papers Calif. Acad. Sci., 

133. 51 p. 
Isaacson, P. A., and R.L. Poole. 1965. New northern records for the spotfin surfperch, Hyperprosopon anale. Calif. 

Fish Game, 51(1):57. 
Kukowski, C. E. 1973. Results of the Sea Grant fishes sampling program for the 1971-1972 season. Moss Landing 

Mar. Lab. Tech. Publ. 73-6, 48 p. 

Miller, D.J., D. Gotshall, and R. Nitsos. 1965. A field guide to some common ocean sport fishes of California. Calif. 
Dept. Fish and Game, Marine Resour. Oper., Sacramento. 87 p. 

Miller, D. J., and R. N. Lea. 1972. Guide to the coastal marine fishes of California. Calif. Dept. Fish and Game, Fish 

Bull., (157):1-235. 
Roedel, P.M. 1953.Commonoceanfishesof the California coast. Calif. Dept. Fish and Game, Fish Bull., (91):1-184. 

Tarp, F.H. 1952. A revision of the family Embiotocidae (the surfperches). Calif. Dept. Fish and Game, Fish Bull., 

(88):1-99. 
Tesch, F. W. 1971. Age and growth. Pages 98-130 /WW. E. Ricker, ed. Methods for assessment of fish production 

in fresh waters. IBP Handbook No. 3, Blackwell Scientific Pub., Oxford, England. 
Warner, R. R., and R. K. Harlan. Sperm competition and sperm storage as determinants of sexual dimorphism in 

the dwarf surfperch, Micrometrus minimus. Evolution, 36:44-55. 
Wilson, D. C, and R. E. Millerman. 1969. Relationships of female age and size in the shiner perch, Cymatogaster 

aggregate. Canada, Fish. Res. Bd., J., 26(9):2339-2344. 

Wydoski, R.S. 1969. Occurrence of the spotfin surfperch in Oregon waters. Calif. Fish Game, 55(4):335. 

Wydoski, R. S., and D. E. Bennett. 1973. Contributions to the life history of the silver surfperch Hyperprosopon 
ellipticum from the Oregon coast. Calif. Fish Game, 59 (3 ):1 78-1 90. 



RODENTICIDE BAIT EXPOSURE TO GEESE 105 

Calif. Fish and Came 69 ( 2 ) : 1 05- 1 1 4 1 983 

HAZARDS TO GEESE FROM EXPOSURE TO ZINC 
PHOSPHIDE RODENTICIDE BAITS ' 

JAMES F. CLAHN' and LARRY D. LAMPER' 

U.S. Fish and Wildlife Service 

Denver Wildlife Research Center 

Fresno, California 93721 

Enclosure studies were conducted on Canada Geese, Branta canadensis mofflt- 
ti, and White-fronted Geese, Anser albifrons, to evaluate bait acceptance and mortal- 
ity of these species from field exposure to 1% zinc phosphide-treated rodent baits 
applied at 1, 3, and 10 times the normal application rate of 6.7kg/ha over hay cover 
crops. Over alta fescue, Festuca arundinacea, Canada Geese died at all toxicant 
levels, but significant weight loss suggested that geese were forced to take bait due 
to a lack of sufficient quantity of forage. Over alfalfa, Medicago sativa, Canada Geese 
for the most part refused the bait and all survived 4 days of exposure in good 
condition. White-fronted Geese over a minimal growth of alfalfa consumed suble- 
thal amounts of bait at all treatment levels but survived exposure in good condition. 

INTRODUCTION 

Zinc phosphide-treated oat groat bait (1%) is commonly used to control 
populations of voles Microtus sp. in western hayfields and certain perennial 
crops. In the Klamath and Tule Lake basins, on the California-Oregon border, 
large populations of geese frequently graze baited fields and may become ex- 
posed to lethal quantities of bait. During operational baiting programs goose 
mortality has been attributed to this rodenticide (Mohr 1959, Keith and O'Neill 
1964); however, these reports suggest exaggerated or unusual exposures of zinc 
phosphide bait to geese. 

The toxicity of zinc phosphide baits to geese has been demonstrated under 
laboratory conditions (Anon. 1962). In these tests. Snow Geese, Chen hyper- 
borea, and White-fronted Geese died after being force-fed 200-300 kernels of 
1% zinc phosphide oat groat bait. Free-feeding studies, however, indicate that 
zinc phosphide-treated baits are repellent and may act as an emetic to certain 
species of birds (Siegfried 1968, Mines and Dimmick 1970). 

We report here on an evaluation of the potential hazards to two species of 
geese from exposure to normal and exaggerated application rates of zinc phos- 
phide rodenticide bait under conditions closely simulating those that exist during 
operational hayfield baiting programs. 

METHODS 

All field testing was conducted at the Tule Lake National Wildlife Refuge, 
Tulelake, California. Sixteen Canada and 16 White-fronted Geese were tested in 
two trials per species of 8 geese each. All geese were wild-trapped adults held 
in captivity for at least 1 month before testing and fed a ration of domestic goose 
or rabbit pellets and water ad libitum. Canada Geese were exposed to zinc 
phosphide baits over two types of hay cover: an alta fescue and alfalfa immedi- 

' Accepted for publication February 1982. 

* Present address; U.S. Fish and Wildlife Service, Denver Wildlife Research Center, Kentucky Research Station, 

Bowling Green, KY 42101. 
' Present address: U.S. Fish and Wildlife Service, Denver Wildlife Kcsearch Center, Denver, CO 80225. 



106 CALIFORNIA FISH AND CAME 

ately after the first hay cutting in |uly 1976. After cutting, both the fescue and 
the alfalfa were about 8 cm high. In both White-fronted Goose trials, the birds 
were exposed to zinc phosphide bait in alfalfa at the beginning of the growing 
season (April 1977), when alfalfa averaged 2.5 cnn high. 

For each trial two geese were randomly assigned to each of four (2.4 X 9.8 
X 1.2 m) portable enclosures assembled on site from 18 (2.4 X 1.2 m) panels. 
The panels were constructed of 1 .9-cm PVC pipe and 2.5-cm poultry netting and 
fastened together with 7-cm worm screw-type hose clamps. The enclosures, 
readily moved by two people, provided 23.5 m ^ of grazing area for each pair 
of geese. 

Geese were acclimated to the enclosures for at least 3 days while their general 
condition and weight were monitored. During this period the only food provided 
to Canada Geese in both trials was the hay cover available on enclosure sites. 
Enclosures were moved daily to provide a new source of forage. Water was 
provided ad libitum. During pretreatment acclimation, White-fronted Geese 
were maintained in a similar manner except that in the first trial, 100 g and 200 
g of alfalfa pellets were offered per day in each of two enclosures, respectively, 
to assess the need of supplemental feeding over the sparse alfalfa growth. 

We formulated the zinc phosphide bait with 1% technical grade (94%) zinc 
phosphide on oat groats (hulled oats) using 1% lecithin/mineral oil (1:1 ) as a 
binder-adhesive and 0.2% Monastral Green B pigment (E. I. DuPont Nemours 
& Co.) as a coloring agent (reference to trade names or commercial suppliers 
does not imply endorsement by the U.S. Government). An inert flourescent 
particle manufactured by Metronics Associates, Palo Alto, California (Tracerite, 
0.1%) was used in the bait to determine the relative amount of bait consumed 
by geese. Previous trials on domestic ducks indicated that these particles were 
voided within 24 h. 

One of three toxicant levels — 1 , 3, and 1 times ( 1 X, 3X, and 1 0X ) the normal 
application rate of 6.7 kg/ha (the equivalent of 16, 48, and 160g, respectively, 
per enclosure site) — was assigned and applied to each site by broadcasting bait 
with a hand seeder. The fourth enclosure in each series was used as an untreated 
control (OX). 

In the second trial with White-fronted Geese the 3X treatment level was 
replaced with a 48-g equivalent of twelve 4-g bait spots placed at 1 .5-m intervals 
within the enclosure. Enclosures were moved daily over newly applied bait for 
4 consecutive days to provide a constant exposure factor and source of forage. 
All geese were observed from 3 to 7 days following the last day of bait exposure. 

Twenty-four hours after each bait application, body weight and physical 
condition of geese were observed and the amount of bait remaining in the 
enclosure was noted. A composite sample of goose droppings was collected 
from each enclosure site to determine the presence and relative amounts of 
Tracerite. Each composite goose dropping sample was hand-mixed and a por- 
tion of the sample diluted with an equal amount of distilled water. Using a 
disposable pipette, we transferred each diluted specimen to a glass slide and 
examined it thoroughly; at least two dilutions were examined to verify the 
presence or absence of Tracerite. Tracerite levels were ranked by average num- 
ber of particles per field into five categories. 



RODENTICIDE BAIT EXPOSURE TO GEESE 107 

Geese found dead during trials were weighed, frozen, and shipped to the 
Denver Wildlife Research Center for gross pathology and residue analysis. Speci- 
mens of gizzard and liver were analyzed for zinc phosphide in the form of 
phosphine (PH3) by the gas-liquid chromatography method (Okuno, Wilson, 
and White 1975). 

Canada Geese surviving field trials were transported to and held in captivity 
at the San Joaquin Experimental Range, Madera County, California. Geese were 
held 7 days for observation on a ration of goose pellets and water. Following 
the observation period we attempted acute oral LD50 determinations for 1% 
formulated zinc phosphide bait and with technical grade zinc phosphide using 
a method described by Thompson (1947) and Weil (1952). The technical zinc 
phosphide was encapsulated in gelatin and introduced into the stomach by 
means of a plastic tube. Geese were fasted 4 h before dosing, placed in individual 
cages where they were initially observed for 30 min after dosing, and then 
observed briefly each day for 7 days after dosing. Two geese were dosed at each 
of four levels; 8, 1 2, 1 8, and 28 mg/kg with technical grade zinc phosphide. Tests 
with formulated baits were similar except that freshly prepared 1% zinc phos- 
phide bait was administered by stomach tubing. Dosage levels were calculated 
by grams of bait and administered in equivalent dosages of 12, 18, 28, 42, and 
62 mg/kg to each of two geese. Because of the limited number of geese avail- 
able, most of the geese surviving the formulated bait test were later used in the 
technical material test 60 days later. 

RESULTS 
Test 1: Canada Geese 

During the pretreatment acclimation before Trial 1, the eight geese feeding on 
alta fescue stuble lost a mean of 7.3% of their initial body weight (range to 
12.5%). However, all geese were healthy and vigorous at the end of the 3-day 
period and testing was completed without supplemental feeding. During the 
4-day exposure period, test geese continued to lose weight and, based on 
Tracerite analysis, consumed lethal and sublethal amounts of zinc phosphide- 
treated bait at all toxicant levels (Table 1 ). Evidence of regurgitation was found 
in the 3X enclosure 24 h after the first bait application and one of the geese died. 
Both 10X geese died 24 h following the second bait application and it appeared 
that most of the bait had been consumed. Following the fourth and last bait 
application one of the geese in the IX enclosure died although no tracerite was 
found in the droppings that day or the previous day. Zinc phosphide residues 
of 27 ppm and higher were found in the gizzards of all geese found dead (Table 
1 ), but no detectable residues were found in the livers. Gross pathology indicat- 
ed that all geese were in varying degrees of emaciation and some congestion 
in the heart and lungs was noted. 

During 3 days of acclimation geese feeding on an alfalfa stubble (Trial 2) lost 
a mean of 1.9% of their initial body weight (range to 6.3%) and testing 
commenced without supplemental feeding. Geese lost a mean of 3.8% (0.1 kg) 
of their body weight during the 4-day testing period (Table 2). However, the 
largest loss was with geese in the control group (0.3 kg) and not the treatment 
groups. Tracerite analysis revealed that geese refused the bait under this test 
regime except in one instance. 



108 



CALIFORNIA FISH AND CAME 



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110 CALIFORNIA FISH AND GAME 

Canada geese surviving both trials showed no effect of treatment during the 
7-day post-treatment observation period, and all were healthy and vigorous 
before the force feeding trials with formulated 1% zinc phosphide bait. Geese 
survived dosages of grain bait at 1.2 g/kg and 1.8 g/kg or the equivalent of 12 
and 18 mg/kg of zinc phosphide. The first death occurred at 2.8 g/kg, or the 
equivalent of 520 kernels of grain. One of two geese dosed at 2.8 g/kg and 4.2 
g/kg died, and both geese died at the 6.2 g/kg dosage. The LD » for formulated 
bait was calculated with 95% confidence limits at 33.09 ( Range = 1 8.62-58.69 ) 
mg/kg. Regurgitation of treated grain was noted at all dosage levels, but became 
increasingly apparent at the higher levels. All deaths occurred within 18 h after 
dosing. 

Geese fed by stomach tube with technical zinc phosphide died at a minimum 
dose of 8 mg/kg. One of two geese dosed at 8, 1 2, and 1 8 mg/kg died, and both 
geese dosed at 28 mg/kg died. The acute oral LD 50 and 95% confidence limits 
were calculated at 12.00 (Range = 2.94-48.89) mg/kg. Regurgitation was not 
observed during this test. Deaths occurred within 24 h of dosing except at the 
8 mg/kg dose which occurred between 48 and 72 h after dosing. 

Test II: White-fronted Geese 
After 4 days of acclimation to enclosures, White-fronted Geese showed no 
improved performance with supplemental feeding; thus supplemental feeding 
was eliminated during the testing period. All geese maintained their initial body 
weight during the 4-day testing period. Tracerite analysis indicated that geese at 
all treatment levels initially consumed sublethal quantities of bait, but consump- 
tion appeared to decrease after the first 2 days of exposure (Table 3). All geese 
survived 4 consecutive days of exposure without weight loss or unusual effects 
except diarrhea, as noted in the 3X and 10X enclosures on day 2 (Table 3). The 
second trial with eight White-fronted Geese was a repetition of the first and 
geese reacted to spot bait and broadcasted treatments in a similar manner. 
Tracerite analysis indicated that bait was consumed in the IX enclosure only on 
day 4 and in the spot bait enclosure on days 1 and 4. In the lOX enclosure 
sublethal quantities of bait were consumed in decreasing amounts on all 4 days 
(Table 3). Again, diarrhea was noted in all treatment enclosures, but no other 
adverse effects were observed. 

DISCUSSION 

Bait acceptance and mortality varied with differences in cover crops, amounts 
of standing forage, and bait application rates. Over fescue stubble Canada Geese 
consumed bait in large enough quantities to cause mortality at all toxicant levels. 
Timing and number of mortalities per enclosure generally corresponded to the 
application rate. Continued weight losses before and during treatment suggest 
that geese were forced to take the grain bait due to lack of sufficient diet on the 
fescue stubble. In contrast, Canada Geese with an ample diet of alfalfa appeared 
to refuse bait except in one instance. Some weight loss during this trial did not 
appear to be treatment related. 

White-fronted Geese, although about half the size of the large Canadas, were 
supplied with about one-third the amount of standing alfalfa forage. Under these 
conditions the White-fronted Geese appeared to accept sublethal quantities of 
bait at all treatment levels, but did not consume sufficient quantities to cause 



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mortality even at 10 times the normal application rate. After consuming sublethal 
quantities of bait, White-fronted Geese appeared to develop an aversion to it 
after 2 days of exposure. Subacute doses of toxicant did not appear to have 
visible adverse effects, except for diarrhea, on either species. Apparently diar- 
rhea was the result of ingesting sublethal amounts of the toxicant and was usually 
associated with the presence of tracerite in the feces. This symptom of zinc 
phosphide poisoning was observed with domestic fowl and had been attributed 
to excessive amounts of bile being excreted (Robertson, Campbell, and Craves 
1945). 

Tests of technical material and formulated bait force-fed to geese indicated 
that these baits are highly toxic and would present a potential hazard to geese 
exposed to them. The difference in toxicity between that calculated for technical 
material and that for formulated baits is not completely known but may be 
associated with the volume of grain necessary to achieve lethal doses resulting 
in regurgitation of a portion of the amount of treated grain administered. For this 
reason we believe the LD » of 12.00 mg/kg for the technical material on the 
Canada Goose to be more accurate. The LD 50 for White-fronted Geese is 
reported to be 7.5 mg/kg and for the Snow Goose, 8.8 mg/kg (Anon. 1962). 
These indicators of toxicity suggest that all species of geese tested are equally 
susceptible to poisoning on a per weight basis. However, the minimum lethal 
dose in kernels of 1% treated grain bait was estimated for White-fronted Geese 
to be between 200-300 kernels (Anon. 1962), whereas our study with similar 
procedures indicates that the minimum lethal dose for the larger Canada Geese 
was about 520 kernels of bait. Further studies with 1% formulated bait (Anon. 
1962) indicated that White-fronted Geese died when fed between 50-100 ker- 
nels of treated bait for up to 5 days. The high gizzard residues in geese found 
dead in our study suggest that all died of acute poisoning, although high subacute 
doses and emaciation may have contributed to mortality. 

Our studies suggest that geese under these testing regimes developed an 
aversion to zinc phosphide-treated bait following ingestion of sublethal quanti- 
ties. In free-feeding studies with other avian species, Bobwhite Quail, Colinus 
virginianus, (Mines and Dimmick 1970), Crowned Guinea Fowl, Numida mela- 
gris, and Laughing Doves, Stigmatopelia senegalensis, (Siegfried 1968) initially 
avoided zinc phosphide-treated bait except under extreme food deprivation. 
Geese, especially White-fronted Geese, did not appear to be as discriminating 
as seed-eating birds in avoiding treated bait. In part, this may be due to bait being 
inadvertently ingested while geese grazed on alfalfa. 

Zinc phosphide is considered to be a strong emetic (Schitoskey 1975). We 
were able to document only one instance of regurgitation during field trials, 
although, based on force-fed trials, we believe it occurred more frequently. In 
studies with Laced-necked Doves, Streptopela chinensis, L. F. Rank (Supervisory 
Wildlife Biologist, U.S. Fish and Wildlife Service, pers. commun.) conducted 
both free- and force-feeding tests with zinc phosphide-treated oat groats. Caged 
doves consistently regurgitated free- and force-fed bait but no other adverse 
effects were noted. We speculate that the emetic action of zinc phosphide may 
have initially presented geese from ingesting lethal quantities of bait and may 
have been responsible for bait aversion developing later in the test. Regardless 



RODENTICIDE BAIT EXPOSURE TO GEESE 113 

of cause and effect, aversion combined with the emetic properties of zinc 
phosphide may have contributed to the survival of geese exposed to treated bait. 

Possibly the most important factor contributing to survival of geese was the 
availability of a preferred food source. The presence and amount of green forage 
(alfalfa) appeared to correspond inversely to the amount of treated bait con- 
sumed. Two documented cases of significant mortality to geese are reported 
from the Tulelake and Klamath Basins and illustrate the definite hazards to geese 
when bait is improperly exposed during periods of relative food scarcity. In 1958 
a confirmed loss of 3,676 geese was attributed primarily to 1% zinc phosphide 
bait used to control voles during one of the worse vole irruptions ever reported 
(Mohr 1959). During February and March alone, about 68,000 kg of bait were 
applied, primarily to dormant alfalfa fields, at rates greater than 22 kg/ ha. Me- 
chanical broadcasting at excessive application rates was blamed for the mortal- 
ity, but the limited forage available after a major vole irruption may have been 
an equally important contributing factor. In late October 1963 a loss of 455 geese 
was attributed to 1% zinc phosphide-treated bait applied to a barley field in late 
July and August at the recommended rate of 7 to 9 kg/ha (Keith and O'Neill 
1964). Subsequent burning of the field in October exposed residual bait and 
barley to geese. These documented kills indicate that geese will accept lethal 
quantities of fine phosphide-treated bait when it is exposed on essentially bare 
ground during stress periods. 

The overall conclusion from the present study is that zinc phosphide-treated 
oat groats pose a relatively low hazard to geese if applied over alfalfa at recom- 
mended rates during periods when sufficient foods are available; however, the 
initial acceptance of zinc phosphide-treated bait by geese mandates that reason- 
able care should be taken to (i) minimize the short- and long-term exposure of 
bait, especially in fields where geese are not apt to discriminate between bait 
and residual grain (barley stubble or Alta fescue), and (ii) coordinate bait 
application with field management regimes insofar as possible until safer rodent 
control measures are developed. 

ACKNOWLEDGMENTS 
We are indebted to R. Fields and E. O'Neill of the Tule Lake National Wildlife 
Refuge for their assistance and cooperation in capturing and maintaining the 
geese and arranging the test sites. This study was partially funded under contract 
with the U.S. Bureau of Reclamation (Contract No. 14-06-200-7231 A). 

LITERATURE CITED 

Anon. 1962. Economic poisons (pesticides) investigations. Calif. Dep. Fish Came, Wildl. Invest. Lab. Job Compl. 
Rep., Pittman-Robertson Wildl. Restoration Proj. No. W-52-B-6. 10 p. 

Mines, T., and R. W. Dimmick. 1970. The acceptance by Bobwhite Quail of rodent baits dyed and treated with 
zinc phosphide. Proc. Annu. Conf. Southeast Assoc. Game Fish Comm., 24:201-205. 

Keith, J. O. and E. J. O'Neill. 1964. Investigations of a goose mortality resulting from the use of zinc phosphide 
as a rodenticide. Unpubl. U.S. Fish Wildl. Serv. Rep. Klamath Basin Refuge. 7 p. (Mimeo) 

Mohr, J. 1 959. The Oregon meadow mouse irruption of 1957-1 958: Influences of the poisoning program on wildlife. 
Fed. Coop. Ext. Serv. p. 27-34. 

Okuno, I., R. A. Wilson, and R. W. White. 1975. Determination of zinc phosphide in range vegetation by gas 
chromatography. Bull. Environ. Contam. Toxicol., 13(4):392-396. 

Robertson, A., J. G. Campbell, and D. Graves. 1945. Experimental zinc phosphide poisoning in fowls. J. Comp. 
Pathol. Ther., 55:290-300. 



1 1 4 CALIFORNIA FISH AND CAME 

Schitoskey, F. 1975. Primary and secondary hazards of three rodenticides to kit fox. J. Wild!. Manage., 39 (2) :41b- 

418. 
Siegfried, W.R.I 968. The reactions of certain birds to rodent baits treated with zinc phosphide. Ostrich, 39 ( 3 ) : 1 97- 

198. 
Thompson, W. R. 1947. Use of moving average and interpolation to estimate median — effective dose. Bacteriol. 

Rev., 11 (2) :1 15-145. 
Weil, C. S. 1952. Tables for convenient calculation of median-effective dose (LD » or ED ») and instructions in 

their use. Biometrics, 8(3):249-263. 



RED ABALONE OVA FERTILITY 1 1 5 

Calif. Fish and Game 69 ( 2 ) ; 11 5-1 20 1 983 

OVA FERTILITY RELATIVE TO TEMPERATURE AND TO 
THE TIME OF GAMETE MIXING IN THE RED ABALONE, 

HAUOTIS RUFESCENS^ 

EARL E. EBERT AND RANDALL M. HAMILTON * 

Marine Resources Branch 

California Department of Fish and Game 

Marine Culture Laboratory 

Granite Canyon, Monterey, California 93940 

Five test temperatures (9X, 12°C, ISX, 18"C and 21'C) were selected along with 
gamete mixing delays up to 8 h to compare ova fertility in the red abalone, Haliotis 
rufescens. At extreme test temperatures (9*0 and 21°C) fertilization success was 
poor even at short gamete mixing delay intervals. Optimum fertilization success at 
the time of spawning and for extended gamete mixing delay intervals was at ^S'Q. 
Overall, fertilization rate was inversely related to the gamete mixing time delay 
period. 

Comparisons of sperm and ova viability loss, at 15°C, revealed that sperm lost its 
viability well in advance of ova. 

INTRODUCTION 

Induced spawning techniques for the red abalone, Haliotis rufescens, have 
been largely perfected by using either heavily ultraviolet irradiated seawater 
(Kikuchi and Uki ^974a) or hydrogen peroxide (Morse eta/. 1977). However, 
spawnings may lack synchrony and other factors may intercede causing both a 
delay in gamete mixing and a loss in gamete viability. 

Inoue (1969) and Kikuchi and Uki (19746) reportedon the duration of fertility 
of spawned gametes relative to temperature for Japanese haliotid species. 
However, such data are lacking for North American haliotids. 

The objectives of this paper are (i) to determine gamete viability loss through 
time relative to spawning onset and gamete mixing, (ii) to determine the rela- 
tionship of temperature to the aforementioned objective, and (iii) to compare 
the viability duration of ova and sperm. Such information is considered valuable 
to the developing abalone mariculture industry in California. 

MATERIALS AND METHODS 

Adult red abalone came either directly from a wild population or from labora- 
tory cultivate (F,) stocks. These stocks were maintained and conditioned at the 
Department's Marine Culture Laboratory (Ebert, Haseltine, and Kelly 1974) 
where all research was performed. Parent stock was conditioned in ambient 
temperature (approximately 11-15 C), 15 /xm filtered, continuous flowing 
seawater, with a natural photoperiod. Holding tanks were cleaned and supplied 
weekly with an excess of fresh giant kelp, Macrocystis sp. 

Testing was conducted in a lucite plastic water table measuring 2.4 m by 0.5 
m by 0.3 m deep. Seven styrofoam containers, each measuring 28.0 cm by 21.0 
cm by 26.0 cm deep, were positioned on the holding table to accomodate the 
culture containers. The latter consisted of 10.2 cm inside diameter PVC pipe 
sections, 11.4 cm high and screened at the base with 90 jam NITEX® to retain 
ova and larvae. The containers were placed on plastic grate shelves situtated to 



' Accepted for publication April 1982. 

' Mr. Hamilton's current address is: Monterey Bay Aquarium, 886 Cannery Row, Monterey CA 93940 



116 



CALIFORNIA FISH AND CAME 



give each culture container a water volume of 0.5 litre (Figure 1). Filtered 
seawater (3 /xnn) was supplied continuously to the seven cultures at a rate of 
about 200 ml/min. Five test temperatures were used: 9 C, 12 C, 15 C, 18 C and 
21 C 




I^^IPIPPPP 






FIGURE 1. Experimental apparatus for holding spawned gametes at test temperatures. 



Mature parent stock was selected based on gonadal bulk and color. One 
male-female pair was used for each test run. Each member of a pair was held 
separately in a 15-1 plastic container. 

Spawning was induced by using heavily ultraviolet irradiated seawater (Kiku- 
chi and Uki 1974a). We used a REFCO^ water purifier, Model RL-10 (REFCO 
Purification Systems Inc, San Leandro, Calif.) and 3 /xm filtered seawater. Water 



RED ABALONE OVA FERTILITY 1 1 7 

flow from the purifier to each of the parent abalones was maintained at about 
150 ml/min. Only synchronous spawners or those that spawned within 30 min 
of one another were used. 

At spawning, about 1,000 ova were pipetted into each of the seven culture 
containers at the predetermined test temperature, ± 0.5 C. Sperm was collected 
at spawning, concentrated in a 1 litre beaker (400,000/ml), unaerated, and 
immersed in a water bath at the test temperature. A 50-ml sperm suspension was 
added to one culture with ova at spawning and served as a control. Thereafter, 
50 ml of sperm suspension was added hourly to successive ova cultures. 

Tests to compare sperm and ova viability were conducted similarly; however, 
they were conducted only at 15 C. Also, one male-female pair was spawned 
synchronously, followed 3 h and 6 h later by separate male-only spawnings. Ova 
were distributed in three containers. Sperm from each male was mixed with one 
of the ova samples at the time of spawning. This gave fresh sperm with h, 3 
h and 6 h old ova. 

Ova fertilization success was determined microscopically using lOOX magnifi- 
cation. Four replicate samples of 30 ova each were used for each determination. 
Successful fertilization was defined as normal cell cleavage at least to the morula 
stage. Fertilization was deemed unsuccessful if cleavage did not occur or if 
cleavage planes were aberrant. Fertilization success means and ranges were 
calculated. 

RESULTS 

Thirty-six test runs were conducted from November 1979 through September 
1980. Of these, 16 were usable and the remainder rejected. Rejection causes 
included (i) asynchronous spawning, (ii) oneor both sexes failed to spawn, (iii) 
failure to observe spawning onset, and (iv) insufficient observations following 
spawning. 

Acceptable test runs included six at 15 C, three at 9 C and 21 C, and two at 
1 2 C and 1 8 C. Four of the 1 5 C test runs compared ova and sperm viability loss. 

Spawning induction time for male abalones exposed to the ultraviolet-irradiat- 
ed seawater took from 2 h 25 min to 4 h, and averaged 3 h 1 min. Concomitant 
temperature rise averaged 4.1 C and ranged from 1.0-6.7 C. Spawning induction 
for female abalones took from 2 h 45 min to 4 h 30 min and averaged 3 h 8 min. 
Concomitant temperature rise averaged 4.3 C and ranged from 1 .3-6.2 C (Table 
1). 

At both temperature extremes (9 C and 21 C) replicate test runs disclosed 
rather wide variations. For instance at 9 C and h post spawning, fertilization 
success ranged from 13% to 97% and averaged 54%; at 21 C and h post 
spawning, fertilization success ranged from 20% to 85% and averaged 65%. 
Gamete viability duration was markedly affected by the 21 C temperature and 
no fertilizations were observed after 1 h. At 9 C fertilization success sharply 
declined after 1 h post spawning, however some fertilization did occur after 5 
h. 

The intermediate test temperatures (12 C, 15 C, and 18 C) yielded more 
uniform results between replicate tests, and significantly better fertilization suc- 
cess at longer time delays in gamete mixing, than did the test temperature 
extremes. However, variations were apparent at extended gamete mixing delay 
periods. For example, duplicate test runs at 1 5 C after a 4 h gamete mixing delay 
yielded 39% and 92% fertilization success. 



118 CALIFORNIA FISH AND CAME 

Tests to compare sperm and ova viability loss revealed that sperm lost its 
viability well in advance of ova. For example, 6 h old ova inoculated with a 6 
h old sperm suspension resulted in 3% fertilization success. But, 6 h old ova 
inoculated with a freshly spawned sperm suspension resulted in 72% fertilization 
success (Figure 2). 

TABLE 1. Temperature Rise And Time To Spawning For Sixteen Test Runs Using The 
Heavily Ultraviolet Irradiated Seawater Spawning Induction Technique. 

Temperature, C 
Test run Initial At spawning Time to spawning, hrmin 

Temp. (C) male and female male female male female 

9 12.0 19.0 19.0 2:25 2:45 

9 12.0 18.0 18.0 3:00 3:00 

9 14.2 19.0 19.0 3:00 3:00 

12 11.1 17.0 17.0 2:51 3:20 

12 14.0 18.3 18.0 3K)0 3:00 

15 14.0 18.5 18.5 2:30 3:00 

15 14.0 18.5 18.8 2:45 2:45 

15' 14.0 19.1 19.1 3:30 3:30 

15' 16.0 19.0 — 2:30 — 

15' 16.0 19.0 — 2:30 — 

15' 16.0 19.0 _ _ _ 

18 12.8 19.5 19.0 4:00 4:30 

18 12.5 18.0 18.4 3:00 3:00 

21 14.5 17.6 18.0 3:36 3:53 

21 17.0 18.0 18.3 3:30 3:30 

21 16.0 18.0 18.0 3:10 3:15 

' Test runs that compared ova and sperm viability loss. 

DISCUSSION 

Approximately one-half of the test runs were unusable; however, this high 
rejection rate was generally not attributable to the spawning induction method. 
In effect, six test runs were rejected because of human factors. For example, 
insufficient observations after spawning in the sampling time interval resulted 
from a change in our sampling plan following initial test runs. Also, later in the 
study period ripe stock became scarce and we had to select from marginally ripe 
abalones. This resulted in one or both sexes failing to spawn, insufficient spawn 
or clumpy ova, and accounted for nearly 50% of the rejections. 

Although wide variation in fertilization success occurred among replicate 
samples at test temperature extremes, and at extended gamete mixing delay 
periods, an inverse relationship was apparent between the fertilization rate and 
the time of gamete mixing post-spawning. This concurs with the observations of 
Kikuchi and Uki (1974/?). However, these investigators used just one pair of 
abalones, H. discus hannai. Possibly some of the variations in fertilization suc- 
cess between our replicate tests were related to genetic differences among the 
parent stocks. Also, we did not acclimate parent stocks to a uniform temperature 
prior to spawning induction and the ambient seawater temperature varied nearly 
5 C during the study period. This could have imposed additional physiological 
stress on the gametes depending upon the magnitude of the differential between 
ambient seawater and the test temperature. 

The tests to compare ova and sperm viability loss revealed that sperm viability 



RED ABALONE OVA FERTILITY 



119 




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FIGURE 2. Abalone fertilization success (mean %) as a function of temperature and time post- 
spawning. The dashed line (15 C graph) indicates the fertilization success obtained 
when newly spawned sperm was added to O h, 3 h and 6 h old ova. 



120 CALIFORNIA FISH AND CAME 

diminished quicker than ova viability. Possibly sperm viability duration can be 
extended by maintaining them at a reduced density, at a lower temperature, with 
aeration or some combination of these. 

Fifteen C apparently is an optimal temperature for fertilization success at 
spawning and for gamete mixing delays. We have also found this temperature 
is optimum for rearing larval and juvenile stage red abalone. 

ACKNOWLEDGMENTS 

This research was supported in part by the Bartlett Commercial Fisheries 
Research and Development Act (PL 88-309) and California Sea Grant College 
Program under grant #R/NP-1-9L to Humboldt State University from the office 
of Sea Grant, National Oceanic and Atmospheric Administration, U.S. Depart- 
ment of Commerce. 

Appreciation is gratefully extended to J. D. DeMartini, Humboldt State Univer- 
sity, who helped initiate the study and to our colleagues at the Marine Culture 
Laboratory for helping in many various ways. 

Appreciation is also extended to R. N. Lea who reviewed the manuscript and 
provided many helpful suggestions. 

LITERATURE CITED 

Ebert, E. E., A. W. Haseltine and R. O. Kelly. 1974. Sea water system design and operations of the Marine Culture 

Laboratory, Granite Canyon. Calif. Fish Came, 60 (1):4-14. 
Inoue, M. 1969. Mass production and transplantation of abalone. Bull. Kanagawa Fish. Exp. Sta. 131:295-307. 
Kikuchi, S. and N. Uki. 1974d. Technical study on artificial spawning of abalone, genus Haliotis II. Effect of irradiated 

sea water with ultraviolet rays on inducing spawning. Bull. Tohoku Reg. Fish Res. Lab. 33:79-86. 
. 19746. Technical study on artificial spawning of abalone, genus Haliotis. IV. Duration of fertility related 

to temperature. Bull. Tohoku Reg. Fish. Res. Lab. 34:73-75. 
Morse, D.E., H. Duncan, N. Hooker, and A. Morse. 1977. FHydrogen peroxide induces spawning in molluscs with 

activation of prostaglandin endoperoxide synthetase. Science, 196:298-300. 



NOTES 121 

Calif. Fish and Game b<i {.2): 121-128 1983 

NOTES 

FIRST CALIFORNIAN RECORD OF THE AMARILLO SNAPPER, 
LUTJANUS ARGENTIVENTRIS 

On 21 April, 1977, an amarillo snapper, Lutjanus argentiventris (Peters), was 
caught by a sportfisherman, George Uman, just inside Oceanside Harbor, San 
Diego County, California, in approximately 1.8 m of water. When received by 
California Department of Fish and Game personnel, the fish had been eviscerat- 
ed but was in otherwise excellent condition. The rose-colored front and yellow- 
ish posterior portion of the body were still quite distinct and the joined, blue 
spots just beneath the eye formed a brilliant blue stripe. The fish was 410 mm 
long and weighed 950 g. Examination of its otoliths revealed six good hyaline 
(winter) zones and the beginning of an opaque margin (summer growth). 

Based upon this specimen, L. argentiventris appeared in a checklist of Califor- 
nia fishes by Hubbs, Follett, and Dempster (1979) and a list of fishes from the 
United States and Canada by Robins et al. (1980); neither publication gave 
details of its capture. 

One of the most recent publications on reef fishes of the tropical eastern 
Pacific (Gulf of California) reported that L argentiventris is "the commonest 
snapper in the Gulf, ranging from Puerto Penasco to Peru and extending north 
outside the Gulf to Bahia Magdalena" (Thomson, Findley, and Kerstitch 1979). 
Fitch's (1952) records from Santa Maria Lagoon, located slightly upcoast from 
the entrance to Magdalena Bay, do not constitute more northerly captures for 
the species. The Oceanside fish, however, does represent a northward extension 
of the range on the outer coast by approximately 1040 km. 

Only one other member of family Lutjanidae, Lutjanus Colorado, has been 
captured off California (Lehtonen 1979). Therefore it was deemed desirable to 
offer a few counts and measurements from Mr. Uman's fish (deposited in the 
fish collection of the Natural History Museum of Los Angeles County — LACM 
36943-1 ) to aid in distinguishing the two species. The following measurements 
were recorded: standard length 325 mm; head length 119 mm; orbit width 23 
mm; snout to pectoral fin insertion 1 20 mm; snout to pelvic fin insertion 1 38 mm; 
snout to dorsal fin insertion 135 mm; snout to anal fin insertion 240 mm; dorsal 
insertion to pelvic insertion 115 mm; length of pectoral fin 100 mm. Counts were: 
dorsal X, 14; anal III, 8; pored scales in the lateral line, 39. The vomerine patch 
of teeth was anchor-shaped with a long posterior extension. 

I wish to thank j. Fitch for his guidance, research assistance and editorial help, 
and H. Frey for suggestions and editorial assistance. C. Avants typed the manu- 
script from my rather rough draft. I especially wish to thank G. Uman for calling 
his catch to my attention and for his willingness to part with it for its scientific 
value. 

Literature Cited 

Fitch, J. E. 1952. Distributional notes on some Pacific Coast marine fishes. Calif. Fish Game, 38(4):557-564. 

Hubbs, C. L., W. I. Follett, and L. ). Dempster. 1979. List of the fishes of California. Calif. Acad. Sci., Occas. Pap., 
133:1-51. 

Lehtonen, P. B. 1979. Colorado snapper, Lutjanus Colorado, taken near Morro Bay adds new family (Lutjanidae) 
to California's marine fish fauna. Calif. Fish Came, 65(2)::2C 122. 



122 CALIFORNIA FISH AND GAME 

Robins, C. R. (Chairman), R. M. Bailey, C. E. Bond, |. R. Brooker, E. A. Lachner, R. N. Lea, and W.B. Scott. 1980. 
A list oi the common and scientific names of fishes from the United States and Canada (fourth edition). Am. 
Fish, See., Spec. Publ. 12, 174 p. 

Thomson, D. A., L. T. Findley, and A. N. Kerstitch. 1979. Reef fishes of the Sea of Cortez. John Wiley & Sons, New 
York, XVII + 302 p. 

— James E. Phelan, California Department of Fish and Came, Marine Resources 
Region. Accepted for publication June 1982. (After a long illness Jim passed 
away on 24 Nov. 1982.) 

EVIDENCE OF BIRTH OF A SEA OTTER ON LAND IN CENTRAL 

CALIFORNIA 

There has been considerable speculation and some circumstantial evidence 
suggesting that sea otters, Enhydra lutris, in the wild, may give birth on land or 
in the water. Scammon (1874) states that otter pups ". . . are brought forth 
upon the kelp . . .". Fisher (1940), referring to the California population, states 
that parturition takes place in kelp beds. Barabash-Nikiforov (1947), at Mednyi 
Island, U.S.S.R., observed two sea otters on shore with newborn pups and 
afterbirth nearby and, therefore concluded that birth takes place on land. Ken- 
yon (1969), in Alaska, determined the orientation of 43 near-term fetuses and 
found about an equal number of them cephalically or caudally oriented. He 
suggests that caudal presentation would be adaptive for aquatic birth, and con- 
cluded that parturition in sea otters normally takes place on land. Sandegren, 
Chu, and Vandevere ( 1 973 ) , in California, observed a sea otter in the water with 
a newborn pup, a bloody ano-genital area and an umbilical cord protruding from 
the vagina. They subsequently observed the passage of blood and afterbirth into 
the water and concluded, probably correctly, that the pup had been born in the 
water. Differences observed in northern versus southern populations were at- 
tributed to differences in haulout behavior; northern populations haulout fre- 
quently and "California otters are rarely seen ashore" (Sandegren et al. 1973). 

The following observations were made in my studies of haulout patterns of 
sea otters. I used a 50 x 80 Questar telescope at a distance of approximately 1 50 
m. Observations were continuous until light conditions precluded seeing the 
otters. Times are Pacific Standard. Conditions for viewing were excellent with 
high overcast and calm winds and seas. 

On 25 May 1981 at 0831 h an otter with a very small pup was sighted 
hauled-out on an intertidal reef located approximately 1 km south of Breaker 
Point, San Luis Obispo Co., California. The female's head, shoulders, and sides 
were dry, indicating that she had been out of the water for more than a few 
minutes. She was vigorously grooming a very small pup that was completely wet, 
showed no signs of life and had small patches of membranous material and 
blood adhering to its pelage. About 5 cm of the umbilical cord was still attached 
to the pup's abdomen and 10 to 20 cm of the cord could be seen protruding 
from the vagina of the female. The female's chest was wet, where the pup lay, 
as were the flippers and ano-genital area. Based on these observations I estimat- 
ed that the pup had been born within a few minutes of being sighted. 

After approximately 2 minutes of grooming by the female the pup began to 
show signs of life by weakly moving its flippers and head. At 0846 h a membra- 
nous bag (about 10 cm in diameter) filled with fluid protruded from the vagina. 



NOTES 123 

At this point the female, lying supinely, stopped grooming the pup, rolled for- 
ward and bit the sack which ruptured and released the fluid. She immediately 
resumed grooming the pup and continued uninterrupted for 98 min In the total 
observation period (432 min) the female groomed the pup 70% of the time 
rested for 26% and self-groomed for only 4% of the period. After the continuous 
98 mm pup-grooming session, grooming bouts were shorter, ranging from one 
to 45 mm. Self-grooming bouts were short (3-8 min) and infrequent Rest 
periods were short (21-31 min), but were more frequent. 

At 0944 h 73 min after observations began, the placenta and associated tissues 
were passed in less than 3 sec. The female paid no attention to the afterbirth 
which was quickly dragged away and consumed by an attending western gull 
Lams ocadentalis. In the remainder of the observation period, no further materi- 
al passed from the female and the vulva appeared clean 

By 0930 h the pup was dry and fluffy and could move all four legs and weakly 
shake Its head. Several times the pup was in a position where nursing could have 
occurred; it nuzzled the female's fur, but I saw no suckling. When the female 
was self-grooming, and occasionally during rest periods, the pup was placed on 
the algae covered rocks, but 83% of its time was spent on the female's chest 
and abdomen. 

These observations reveal some interesting aspects of the behavior of parturi- 
ent sea otters in California. The mother spends much of the time grooming the 
neonate. This probably has several functions, i.e. cleaning, stimulating circulation 
and breathing of the newborn, and possibly establishing and reinforcing the 
maternal bond. Birth sometimes occurs on land. In this instance there were no 
nearby large expanses of giant kelp, Macrocystis pyrifera. The dominant kelp is 
bull kelp, Nereocystis lutkeana, which in this area does not form a dense surface 
canopy until July. In such areas pupping on land may occur, and in areas where 
beds of kelp persist throughout the year, aquatic births (as reported by Sandegr- 
en er j/. 1973) may be common. Therefore, environmental differences and 
individual variation are probably more important in determining the place of 
parturition in sea otters than are behavioral differences between populations. 

LITERATURE CITED 

Barabash-Nikiforov I. I. 1947 Kalan (The sea otter, in Russian, translated by Dr. A. Birron and Z. S Cole 1962) 

Israel Program for Scientific Translations, Jerusalem. 227 pp. 
Fisher, E. M. 1940, Early life of a sea otter pup. J. Mammal., 21 (2):132-137. 

"^^^ Washin^onl^C^SsYpp °"^' '" """ ^'''''" '''''^'' °'''"- "^^ ^"'^'- ^'""'- ^- ^'^^ ^°^- ''^'"^'"^ Off. 
Sandegren,^F^E^W. Chu, and J. E. Vandevere. 1973. Maternal behavior in the California sea otter. J. Mammal., 

^"Tr;5 ^„o®^'*- ^^^ ""^''"^ mammals of the northwestern coast of North America. John H. Carmany, San 
rrancisco. ji9 pp. " 

T^J^ZI^JrJ- i^'^^'"'''' ^-^- ^^^ ^^d Wildlife Service, P.O. Box 67, San Simeon, 
LA. 93452. Accepted for publication October 1981. 



124 CALIFORNIA FISH AND CAME 

AGE AND GROWTH AND LENGTH-WEIGHT RELATIONSHIP FOR 

FLATHEAD CATFISH, PYLODICTIS OUVARIS, FROM COACHELLA 

CANAL, SOUTHEASTERN CALIFORNIA 

Flathead catfish were introduced in 1962 into Martinez Lake, Arizona, on the 
lower Colorado River (Anonymous 1980). They quickly spread into canals of 
the Imperial Valley, California (Bottroff, St. Amant, and Parker 1969), and up- 
stream in the river to Parker Dam (Minckley 1973). To date, nothing has been 
published on age and growth or length-weight relationship of the species from 
this area. Flathead catfish are native to the Rio Grande-Mississippi River complex 
of central North America (Clodek 1980). 

METHODS AND MATERIALS 

Three sections of the Coachella Canal (T11S, R15E, and T15, R19E, San 
Bernardino Meridian) were blocked by 2.5-cm-mesh nets prior to a water out- 
age (Minckley 1981 ). When water levels receded, sections were further isolated 
by earthen dikes. A concrete box siphon that comprised one study section was 
breached and water was pumped from the structure to allow access and sam- 
pling. Emulsifiable rotenone was applied to all sections at greater than 2.5 mg/ 
liter active ingredients and affected fishes were collected by nets and seines. 

Fish were measured to the nearest centimetre from the tip of the lower jaw 
to the tip of the caudel fin and weighed in pounds (later converted to metric 
system) in the field. Fish less than 15 cm long were preserved in 10% formalin 
for analysis in the laboratory. No adjustments were made for possible changes 
in length or weight following preservation. 

Pectoral spines were disarticulated and excised, dried after removal of soft 
tissues in dilute potassium hydroxide, and sectioned with a jeweler's saw follow- 
ing procedures of Turner (1977). Thin sections were polished on emery paper 
and examined under alcohol and reflected light with a binocular microscope. 
Spine diameters at the point of sectioning were measured to the nearest 0.1 mm 
by Vernier calipers; anterior radius and anterior radius to each annulus were 
recorded to the nearest 0.01 mm by ocular micrometer. 

Back calculation of lengths at consecutive annuli was by the equation: 

L' = C -f S7S(L - C), 

where L' is fish length when annulus "x" was formed, L is the length at capture, 
S' is the anterior spine radius at the n* annulus, S is total anterior spine radius, 
and C is the intercept value from least squares linear regression of fish length and 
spine diameter at the point of sectioning. Size-frequency distribution clearly 
segregated fish of Age Group 0, and this was verified by examination of spines 
from 10 young-of-the-year fish of varying lengths. 

RESULTS AND DISCUSSION 

Flathead catfish comprised about 1.0% (94 specimens) of about 9,000 fishes 
taken in sampling from the Coachella Canal (Minckley 1981 ). Other abundant 
fishes included channel catfish, Ictalurus punctatus; bluegill, Lepomis macro- 
cA/ri/s; largemouth bass, Micropterus sa/moides; ihreadi'm shad, Dorosoma pete- 
nense; red shiner, Notropis lutrensis; and carp, Cyprinus carpio. All are included, 
when of appropriate size, in the diet of flathead catfish in the lower Colorado 
River (Minckley 1982). Fishes were abundant, with 0.55 to 1.08 individuals 
/m ^ recovered. Biomass also was high, with 49.4 and 102.0 g/m ^ in the two 
samples from the open canal, and 593.9 g/m ^ in the siphon (25% of the latter 
were flathead catfish; Minckley 1981). 



NOTES 



125 



Spine diameter at the point of sectioning correlated highly (r — 0.98) with 
length of flathead catfish, with the regression described by the formula Y 
= 1 3.6 + 1 37X. Calculated lengths at each annulus (Table 1 ) compared favora- 
bly with age groups indicated by length-frequency distribution (Figure 1 ), and 
with lengths at capture of the next youngest year classes. Since no indications 
of annuli were near spine edges of any age group, the fish would presumably 
have grown prior to annulus formation in January (the coolest month in the 
region; Jaeger 1957) to approximate calculated lengths at annuli. Length-weight 
relationship is described by the formula Log W = —5.2500 + 3.1441 Log L. 




TOTAL LENGTH, CM 



FIGURE 1 . Size frequency distribution of 75 flathead catfish from the Coachella Canal, California. 
Numbered brackets indicate ranges in total length at capture for fish aged by examina- 
tion of pectoral spines. Some lack of correspondence with Table 1 results from addi- 
tional fish being included here. 

Growth rates of flathead catfish from the Coachella Canal were comparable 
to, or exceeded, those in reservoirs and rivers within their native range (Table 
2 ) . Their length-weight relationship is, expectedly, more like riverine populations 
than those in reservoirs. 



ACKNOWLEDGMENTS 
The U.S. Bureau of Reclamation, Boulder City, Nevada, supported this study 
with funding (Purchase Order No. 1-01-30-04780), equipment, and manpower. 
W. Rinne of the Bureau deserves special thanks. The California Department of 
Fish and Game also provided assistance. 



126 



CALIFORNIA FISH AND CAME 



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LITERATURE CITED 

Anon. 1980. Special report on distribution and abundance of fishes of the lower Colorado River. Final Rept. U.S. 

Bureau Reclamation, Boulder City, Nev., Contr. No. 9-O7-O3-X0O66, U. S. Fish Wildl. Serv., Phoenix, Ariz, ii 

+ 157 p. 
Bottroff, L., ]. A. St. Amant, and W. Parker. 1969. Addition of Pylodictis olivarisXo the California fauna. Calif Fish 

Game, 55(1):90. 

Cross, F. B., and C. E. Hastings. 1956. Ages and sizes of thirty-nine flathead catfish. Kans. Acad. Sci., Trans. 

59(1):85-86. 
Clodeck, G. S. 1980. Pylodictis olivaris (Rafinesque), flathead catfish, p. 472, in D. S. Lee, etal., eds. Atlas of North 

American Freshwater Fishes. N. C. State Mus. Nat. Hist., Raleigh, N. C. x -(- 854 p. 

Jaeger, E. C. 1957. The North American Deserts. Stanford Univ. Press, Stanford, Calif, x + 308 p. 

Jenkins, R. M. 1954. Growth of the flathead catfish, Pylodictis olivaris, in Grand Lake, Oklahoma. Okla. Acad. Sci., 

Proc., 33(1): 11-20. 
McCoy, H. A. 1953. The rate of growth of flathead catfish in twenty-one Oklahoma lakes. Okla. Acad. Sci., Proc., 

34(1): 47-52. 

Minckley, W. L. 1973. Fishes of Arizona. Ariz. Came Fish Dept., Phoenix, Ariz, xvi -(- 293 p. 
. 1981. Fishery inventory of the Coachella Canal, southeastern California. Final Rept. U. S. Bureau Reclama- 
tion, Boulder City, Nev., Purch. Ord. No. 1-01-30-04780, Ariz. State Univ., Tempe, Ariz, ii + 25 p. 
-. 1982. Trophic interrelationships among introduced fishes of the lower Colorado River, southwestern 



United States. Calif. Fish Game, 68(2): 78-89. 
Minckley, W. L. and J. E. Deacon. 1959. Biology of the flathead catfish in Kansas. Amer. Fish. Soc, Trans., 88(4): 
344-355. 

Turner, P. R. 1977. Age determination and growth of flathead catfish. Unpubl. Dissertation. Okla. State Univ., 
Stillwater, Okla. 146 p. 

— Mark S. Pisa no, Mary J. Inansci, and W. L. Minckley, Department of Zoology, 
Arizona State University, Tempe, Arizona 85287. Accepted for publication Janu- 
ary 1982. 



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