CAUPDRNIA FISH- GAME "CONSERVATION OF WDLDUTE THROUGH EDUCATION" California Fish and Game is a journal devoted to the conservation and understanding of fish and wildlife. 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 $10 per year by placing an order with the California Department of Fish and Game, 1416 Ninth Street, Sacramento, CA 95814. Money orders and checks should be made out to California Department of Fish and Game. Inquiries regarding paid subscriptions should be directed to the Editor. Complimentary subscriptions are granted on an exchange basis. Please direct correspondence to: Perry L. Herrgesell, Ph.D., Editor California Fish and Game 1416 Ninth Street Sacramento, CA 95814 u D VOLUME 72 APRIL 1986 NUMBER 2 Published Quarterly by STATE OF CALIFORNIA THE RESOURCES AGENCY DEPARTMENT OF FISH AND GAME —LDA— 66 CALIFORNIA FISH AND CAME STATE OF CALIFORNIA GEORGE DEUKMEJIAN, Governor THE RESOURCES AGENCY GORDON VAN VLECK, Secretary for Resources FISH AND GAME COMMISSION BRIAN J. KAHN, President Santa Rosa ABEL C. GALLETTI, Vice President WILLIAM A. BURKE, Ed.D., Member Los Angeles Brentwood ROBERT BRYANT, Member ALBERT C. TAUCHER, Member Yuba City Long Beach HAROLD C. CRIBBS Executive Secretary DEPARTMENT OF FISH AND GAME JACK C. PARNELL, Director 1416 9th Street Sacramento 95814 CALIFORNIA FISH AND GAME Editorial Staff Editorial staft f-r this issue consisted of the following: Wildlife William E. Grenfell, Jr. Anadromous Fish Kenneth A. Hashagen, Jr. Marine Resources Robert N. Lea, Ph.D. Stnped Bass Donald E, Stevens Environmental Services Kim McCleneghan, Ph.D. Editor-in-Chief Perry L. Herrgesell, Ph.D. CONTENTS 67 Page Epidermal Tumors in Microstomus pacificus (Pleuronectidae) Collected Near a Municipal Wastewater Outfall in the Coastal Waters off Los Angeles (1971-1983) Jeffrey N. Cross 68 The Occurrence of Two Nematodes, Spirocerca lupi and Dirofilaria immitis, in Wild Canids of the Lake Berryessa Area, Northern California M. M. J. Lavoipierre, T. W. Graham, L. L. Walters, and J. A. Howarth 78 Growth and Reproduction of Spot Prawns in the Santa Barbara Channel John S. Sunada 83 Fawn Rearing Habitat of the Lake Hollow Deer Herd, Tehama County, California Heather J. Welker 94 Fawn Mortality in the Lake Hollow Deer Herd, Tehama Coun- ty, California Heather J. Welker 99 Movement of Two Nearshore, Territorial Rockfishes Previous- ly Reported as Non-movers and Implications to Manage- ment Kathleen R. Matthews 103 Relating Marten Scat Contents to Prey Consumed ....William J. Zielinski 110 NOTES First Record of Hemitripterus bolini, the Bigmouth Sculpin, from California Waters Robert N. Lea and Lawrence F. Quirollo 117 Northern Range Extension for California Tonguefish, Sym- phurus atricauda to Washington State Paul A. Dinnel and Christopher W. Rogers 119 Indigenous Muskrats, Ondatra zibethicus, in Coastal Southern California Paul E. Langenwalter II 121 Mortality of American Wigeon on a Golf Course Treated with the Organophosphate, Diazinon E. E. Littrell 122 The Occurrence of Lepas anatifera on Zolophus californianus and Mirounga angustirostris Jan Roletto and Robert Van Syoc 124 Book Reviews 127 68 CALIFORNIA FISH AND GAME Calif. Fish and Game 72 ( 2 ) : 68-77 1 986 EPIDERMAL TUMORS IN MICROSTOMUS PACIFICUS (PLEURONECTIDAE) COLLECTED NEAR A MUNICIPAL WASTEWATER OUTFALL IN THE COASTAL WATERS OFF LOS ANGELES (1971-1983) ^ JEFFREY N. CROSS Southern California Coastal Water Research Project 646 W. Pacific Coast Highway Long Beach, California 90806 The long-term temporal and geographic trends in the incidence of epidermal tumors in the Microstomas pacificus population on the mainland shelf off the Palos Verdes Peninsula are described. From 1971 through 1983, 501 M. pacificus (1.2% of total) with epidermal tumors were collected in 672 otter trawls. Tumors were gener- ally confined to smaller individuals; 2.5% of the fish smaller than 150 mm sl were affected compared to 0.1% of the fish larger than 150 mm sl. The annual incidence of tumors in M. pacificus declined at one of the four sam- pling sites and remained unchanged at the other three. Geographically, the incidence of tumors was higher closer to the wastewater outfalls. The data suggested that tumorous M. pacificus do not participate in the annual offshore migration to the same extent as unaffected individuals. INTRODUCTION Fin erosion and epidermal tumors are the most visible and prevalent external abnormalities observed in fish collected near the municipal wastev^ater outfalls in the coastal waters off Los Angeles (Mearns and Sherwood 1974, 1977; Sher- wood and Mearns 1977). The status of fin erosion was reviewed recently (Cross 1985). The status of epidermal tumors has not been reviewed since the mid- 1970's. Also known as X-cell tumors (Brooks, McArn, and Wellings 1969), they occur on the epidermis of some Bothidae, Pleuronectidae, and Gobiidae in the North Pacific Ocean (Cooper and Keller 1969; McArn and Wellings 1971; Miller and Wellings 1971; Mearns and Sherwood 1974; Ito, Kimura, and Miyake 1976; Oishi, Yamazaki, and Harada 1976; Wellings, McCain, and Miller 1976; McCain, Myers, and Gronlund 1978; Campana 1983) and on the parabranchial gland of some Gadidae and Scorpaenidae in the North Atlantic and North Pacific oceans (Dawe, Bagshaw, and Poore 1979; McCain etal. 1979; Myers 1981; Watermann and Dethlefsen 1982). The objective of this study was to determine the long-term temporal (annual and seasonal) and geographic trends in the incidence of epidermal tumors in the Microstomus pacificus population in the coastal waters off Los Angeles from 1971 through 1983. METHODS The data analyzed in this study were collected by the Los Angeles County Sanitation District during regular monitoring cruises. The station numbers used herein are their designations. The data consisted of catch records of fishes and the frequency of tumors along seven transects on the Palos Verdes shelf ( Figure 1 ). Trawls were made during daylight hours at three depths (23, 61, and 137 m) ' Accepted for publication Novemtjer 1985. Contribution number 199 from Southern California Coastal Water Research Project. \ MUNICIPAL OUTFALLS AND FLATFISH TUMORS 69 with an otter trawl towed along a depth isobath at 1.1 m/s for 10 min. A 7.3-nn (headrope length) otter trawl was used from 1971 to 1974 when it was replaced with a 7.6-m trawl; a 1.25-cm mesh cod-end liner was used in both nets. Fishes were sorted from the catch by species and measured to the nearest mm standard length (sl) on a measuring board if there were few individuals or to the nearest cm SL if there were many individuals. The presence of epidermal tumors was noted. LOS ANGELES HARBOR FIGURE 1. Map of the transect stations on the Palos Verdes shelf. From 1971 through 1978, two samples were collected annually at each depth — one between April and June, the other between October and December. Additional trawls made at irregular intervals were included in the analyses. Quarterly trawling began in 1979 and has continued to the present. Trawling was discontinued at transects T2, T3, and T6 in 1977. Trends in the annual incidence of epidermal tumors from 1971 through 1983 were determined by linear regression of the proportion of fish with tumors against time for each transect. All trawls made within a calendar year at transects TO, Tl, T4, and T5 were pooled for each transect because of the low frequency of tumors in the M. pacificus population. Proportions (p) were transformed to the arcsin (p''') to make the data conform more closely to the assumptions of regression analysis (Finney 1973). Annual tumor frequencies of zero were re- placed by %n (Bartlett 1937). Time was coded as year of collection numbered consecutively from 1971 through 1983 (e.g., 1,2,3, . . ., 13). Trend analyses were performed on data for individuals less than 120 mm sl which accounted for 79.8% of all tumorous M. pacificus (382) collected at transects TO, Tl, T4, and T5. According to the growth curves in Sherwood (1980), fish 120 mm SL were approximately two years old and probably had spent two summers on the mainland shelf. Visual analysis and runs tests of the residuals suggested linear relationships. The quarterly trawls (1979-1983) from 61 and 137 m were examined for seasonal trends in the incidence of tumors and the total catch of M. pacificus. Transects TO, Tl, T4, and T5 were combined for each quarter because of the low 70 CALIFORNIA FISH AND CAME frequency of tumors. Seasonal trends were estimated from: Y, = f(J„ S,) + e, where Y, = the proportion with tumors at t, T, = the trend component at time t, S, = the seasonal component at time t, e, = the remaining components (cyclical and aperiodic) at time t, and f\s a function relating the observed value of the time series to the trend, seasonal, and remaining components ( Bowerman and O'Connell 1979). Regressions were fitted to the incidence data to estimate T (the regression coefficient) for each quarter. The trend was eliminated by dividing the quarterly Y values by T. S was then estimated for each quarter (assuming e was small), normalized to four (the number of quarters in one year), and multiplied by 100. The seasonal index (S,) is a correction factor (in percent) that adjusts for seasonality in the time series. Multiplicative and addi- tive models were fitted to the data; multiplicative models gave a better fit (i.e., lower normalized residual sum of squares). Between 1971 and 1972, a sample of 100 tumorous M. pacificus collected by trawls by various agencies from the Palos Verdes shelf, Santa Monica Bay, and San Pedro Bay were preserved aboard ship and returned to the laboratory for examination. The fish were measured to the nearest mm SL and the location, number, and size of the tumors on each fish were recorded. RESULTS From 1971 through 1983, 501 tumorous M. pacificus (1.2% of all individuals) were collected in 672 otter trawls on the Palos Verdes shelf. Tumors in M. pacificus were confined primarily to smaller individuals; 2.5% of the fish smaller than 150 mm SL were affected compared to 0.1% of the fish larger than 150 mm SL ( Figure 2 ) . Tumors were first observed in fish 50-59 mm SL and most frequent- ly encountered in fish 100-109 mm SL; of all tumorous fish, only 0.1% were larger than 150 mm sl. The proportion of M. pacificus with tumors increased rapidly with fish size, peaking in fish 80-89 mm sl, and declined rapidly thereafter (Figure 3). NONTUMOROUS' TUMOROUS' 100 140 220 260 300 STANDARD LENGTH (MM) FIGURE 2. Size distribution of tumorous and nontumorous Microstomus pacificus collected on the Palos Verdes shelf from 1971 through 1983. MUNICIPAL OUTFALLS AND FLATFISH TUMORS 71 LU O \n Q. *^r''^^^^^^~nr"'^r'^r'"T'^^^^^^^^i^^^f^^^i^i^T^n 40 80 120 160 200 240 STANDARD LENGTH (MM) FIGURE 3. Percent of all Microstomus pacificus collected on the Palos Verdes shelf from 1971 through 1983 with epidermal tumors by 10 mm size class. Among the sample of 100 tumorous M. pacificus collected in 1971 and 1972, there was no correlation between the number of tumors per fish and fish size (r= -.131,.10'<.20) ( Figure 4). The fish ranged from 61 to 208 mm SL with a mode between 100 and 120 mm; 3.0% were larger than 150 mm. There was a significant correlation between tumor size and fish size (r = .643, P<.001) (Figure 5). Of the individuals with only one tumor (n = 46), 54.3% had it on the eyed side, 37.9% had it on the blind side, and 8.7% had it extend onto both sides. Of the individuals with more than one tumor (n = 54), 50.0% had tumors on both sides, 25.9% had tumors only on the eyed side, 13.0% had tumors only on the blind side, and 11.1% had at least one tumor extending onto both sides. Disregarding individuals with tumors on both sides, the ratio of fish with tumors on the eyed side to fish with tumors on the blind side was not significantly different from 1:1 (x' = 3.57, n = 63, .05
.25). There were significant differences among the inter-
cepts ( F = 1 2.79, P < .001 ) however, a Newman-Keuls multiple range test could
not detect which transects were significantly different. The prevalence of tumor-
ous individuals was significantly higher (x^ = 25.4, P< .001 ) at transects closer
to the outfall (Tl, T4, and T5) than at the transect farthest away (TO) (Figure
6).
72
CAIIFORNIA FISH AND CAME
Time series analyses of the quarterly trawl data (1979-83) showed seasonal
differences in both the proportion of M. pacificus with tumors and the number
of M. pacificus caught per trawl ( Figure 7) . Interestingly, the trends were oppo-
site: total catch was highest in spring and summer, while tumor incidence was
highest in fall and winter.
12 n
10-
co
I- 6 -J
4-
2 -
• •••• •••2«
• 3 •2*2M«222 3 22 •
• ••2 2« 2«M 2«3*55 6#»««
• •
2«
60
— I—
80
T 1 1 1 1 1 1 r\N I I
100 120 140 160 210
STANDARD LENGTH (MM)
FICiURE 4. Number of epidermal tumors per Microstomus pacificus as a function of fish standard
length. Numbers indicate multiple individuals.
TABLE 1.
The Number of Microstomus pacificus Less Than 120m (SL) Collected and the
Percent With Epidermal Tumors at Four Transects (TO, T1, T4, and T5 ) on the Palos
Verdes Shelf From 1971 Through 1983.
TO
No. %
1971 26 0
1972 522 0.4
1973 82 3.7
1974 9 0
1975 7 0
1976 3 0
1977 26 0
1978 6 0
1979 48 4.2
1980 77 3.9
1981 82 3.7
1982 125 0
1983 251 0.8
Total 1264 1.2
Tl
No.
26
55
15
34
3
108
135
84
69
66
103
22
93
814
%
15.4
10.9
12.5
0
0
4.6
3.7
1.2
5.8
3.0
5.8
0
1.1
4.4
No.
17
115
268
37
22
163
840
213
398
378
530
332
96
3409
T4
%
11.8
10.4
9.0
2.7
22.7
6.1
i.l
0.9
4.0
2.6
1.3
8.7
6.3
4.4
No.
91
52
57
73
36
137
311
189
357
705
237
403
269
2917
T5
%
7.7
1.9
14.0
1.4
2.8
6.6
5.5
2.6
3.1
1.0
3.0
4.0
4.8
3.5
MUNICIPAL OUTFALLS AND FLATFISH TUMORS
50 T •
40-
73
2
UJ on
N "^^
CO
§20
10-
0
• •
••••• •
• ••*
T-*
* •••• * «•!•••• •
/A-
— I 1 1 1 1 1 1 1 1 I
60 80 100 120 140 160
STANDARD LENGTH (MM)
FIGURE 5. Tumorsize (largest dimension) as a iunci\on oi Microstomus pacificus standard
Only the largest tumor was measured on individuals with multiple tumors.
— •
210
length.
LU
O
CC
LU
0.
5tT4 T6
T1
TO
61M
137M
T
5 10 15 20
DISTANCE FROM OUTFALL (KM)
25
FIGURE 6. Percent of all Microstomus pacificus less than 120 mm SL with epidermal tumors as a
function of distance from the municipal wastewater outfalls on the Palos Verdes shelf.
The sampling transects are labeled at the top.
74
CALIFORNIA FISH AND CAME
TABLE 2. Trend Analyses for Microstomus pacificus Less Than 120 mm si Collected at Four
Transects on the Palos Verdes Shelf (1971-1983). Y = Arcsin (p ) Where p =
Proportion With Epidermal Tumors; X = Time in Years Numbered Consecutively
from 1971 (e.g., 1,2,3, . . ., 13); CI = 95% Confidence Interval of the Slope; P =
Probability That the Slope = 0.
Regression
TO Y = 9.233 -0.033X
Tl Y = 18.930- 1.022X
T4 Y = 19.048 -0.706X
T5 Y = 13.801 -0.321X
CI
P
0.733 to 0.667
P>O.SO
1.913 to -0.091
P<0.05
1.680 to 0.268
P>010
1.034 to 0.392
P>0.50
61M«-
B
^ 200-
137M«
X
111
Q
<
Z
o
CO
<
UJ
CO
100
200-
100
0-
<
I
z
Q.
O
D
UJ
LU
->
1
CO
1
Q
cc
-1
1-
Q.
D
o
<
->
n
FIGURE 7. Seasonal index for (A) the proportion of Microstomus pacificus with epidermal tumors
and (B) the total catch of M. pacificus per trawl from 1979 through 1983.
DISCUSSION
The incidence of epidermal tumors in M. pacificus was highest in fish less than
two years old. Based on an age-length key for M. pacificus collected in 1972 and
1973 (Cross 1985), only 6.2% of the tumorous individuals collected between
1971 and 1983 were age two or older. Epidermal tumors of presumed similar
etiology were restricted to the youngest individuals in several other species of
Pleuronectidae from the West Coast (Cooper and Keller 1969, McArn and
Wellings 1971, Wellings et al. 1976, Campana 1983).
Tumors were not observed on the smallest M. pacificus recruits (40-49 mm
sl) in the first quarter (January-March), but appeared in larger fish (50-59 mm
sl) in the second quarter (April-June). Similarly, Campana (1983) found that
Platichthys stellatus (Pleuronectidae) in Puget Sound settled from the plankton
as early as May but the first tumors did not appear until July.
There was no correlation between fish size and number of tumors per fish and
fish with tumors on the eyed side were not significantly more abundant than fish
with tumors on the blind side. Wellings et al. (1976) reported that tumors were
more abundant on the eyed side in Parophrys vetulus and Hippoglossoides
elassodon ( Pleuronectidae ) .
There was a correlation between fish size and tumor size: larger fish had larger
tumors (Sherwood and Mearns 1976). Campana (1983) found that tumors on
MUNICIPAL OUTFALLS AND FLATFISH TUMORS 75
P. stellatus continued to grow as the fish grew; there was no evidence for tumor
regression. Similarly, Miller and Wellings (1971) found no evidence of tumor
regression in H. elassodon from northern Puget Sound.
The rapid decline in the proportion of tumorous M. pacificus with increasing
fish size suggests that either i) tumorous fish have higher mortality rates than
nontumorous fish or ii) tumorous fish have higher emigration r^tes from the
study area. The former hypothesis is supported by data of Campana ( 1 983 ) , who
found that tumorous P. stellatus were more susceptible to stress, had lower
growth rates, and had much higher mortality rates than nontumorous individu-
als, and by the data of Miller and Wellings (1971 ), who found that tumorous
H. elassodon had lower growth rates and higher mortality rates than nontumor-
ous individuals.
The proportion of M. pacificus with tumors was highest in the fall and winter
when the total catch was lowest. The seasonal pattern of total catch is the result
of an annual onshore-offshore migration. M. pacificus move into shallow water
to feed in the spring and summer and move back into deeper water in the fall
and winter ( Hagerman 1 952 ) . Seasonality was more pronounced at the shallow-
er depth. The higher proportion of tumorous fish on the Palos Verdes shelf in
the fall and winter suggests that tumorous individuals do not participate in the
offshore movement to the same extent as do nontumorous individuals. Stich,
Acton, and Forrester (1976) suggested that the emigration of juvenile Parop/?rys
vetulus from shallow nursery areas to deeper water off British Columbia may be
slower in individuals with epidermal tumors.
The annual incidence of tumors in M. pacificus did not change at transects
TO, T4, and T5 from 1971 through 1983 but declined significantly at T1. The
incidence of fin erosion in the M. pacificus population declined significantly at
all transects during this period (Cross 1985). Declines in the incidence of fin
erosion were correlated with declines in the mass emission of contaminants from
the outfalls and declines in the body burden of contaminants among M. pacifi-
cus. The decline in tumor incidence at T1 suggests that tumors were somehow
affected by reduced contamination in the environment.
There was a significant geographical difference in the incidence of tumors in
M. pacificus less than 120 mm SL: 1.2% of all individuals collected at TO had
tumors while 4.4% of the individuals at T1, 4.4% of the individuals at T4, and
3.5% of the individuals at T5 had tumors. The incidence of epidermal tumors
in the M. pacificus population apparently is enhanced near the outfalls (Figure
6). Similarly, the incidence of fin erosion in the M. pacificus population is
enhanced near the outfalls (Cross 1985). Among all M. pacificus less than 120
mm SL collected from 1971 through 1983, 16.9% had fin erosion, 3.2% had
epidermal tumors, and 1.1% had both diseases. The two diseases were not
independent; significantly more individuals were afflicted with both diseases
than predicted (X^ = 45.4, P<.001).
Cooper and Keller (1969) and Stich et al. (1976) found elevated epidermal
tumor incidence in P. vetulus in urban estuaries and Sindermann (1983) tenta-
tively associated X-cell tumors with environmental degradation. Mearns and
Sherwood (1976), however, concluded that the incidence of epidermal tumors
in M. pacificus populations in southern California was not enhanced by munici-
pal wastewater discharge. They cited as evidence the occurrence of tumorous
individuals in areas far from municipal wastewater discharges (see also Sher-
wood and Mearns 1976). The occurrence of epidermal tumors in pleuronectids
far from degraded environments may be related to the etiology of the disease.
76 CALIFORNIA FISH AND GAME
Recent evidence suggests that the X-cell is a unicellular protozoan parasite
resembling parasitic amoebae (Dawe et al. 1979, Dawe 1981, Myers 1981,
Watermann and Dethlefsen 1982) although not everyone agrees w\ih this inter-
pretation (Peters, Stich, and Kranz 1981, Peters et al. 1983). Newly recruited
pleuronectids may be susceptible to epidermal tumors because of contaminant-
induced stress and/or an incompletely developed immune system (Sindermann
1983).
ACKNOWLEDGMENTS
I would like to thank Los Angeles County Sanitation District for access to the
monitoring data, A. J. Mearns and M. J. Sherwood for access to the tumor data
on Dover sole collected in 1971 and 1972, and M. Martin for helpful comments
on an earlier version of the manuscript.
LITERATURE CITED
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78 CALIFORNIA FISH AND CAME
Calif. Fish and Came 72 ( 2 ) : 78-82 1 986
THE OCCURRENCE OF TWO NEMATODES, SPIROCERCA
LUPI AND DIROFiLARIA IMMITIS, IN WILD CANIDS OF
THE LAKE BERRYESSA AREA, NORTHERN CALIFORNIA^
M. M. J. LAVOIPIERRE \ T. W. CRAHAM ^ L. L. WALTERS ', and J. A. HOWARTH
Department of Epidemiology and Preventive Medicine
School of Veterinary Medicine
University of California
Davis, California 95616
Spirocerca /up/' was found in 4 of 17 (24%) gray foxes, Urocyon cinereoargenteus,
trapped at Lake Berryessa, northern California. The nematodes, dissected from
granulomas, were located in the upper colon and ileo-colic portion of the gut. Five
adult Dirofilaria immitis were found in the heart of one of the foxes. D. immitis was
found also in the hearts of three of four coyotes, Canis latrans, taken in the same area
(23, 36 and 94 adult nematodes).
INTRODUCTION
During a study of the ecology of carnivore tapeworms in northern California,
including the City of Davis and surrounding area, a number of wild canids were
captured for necropsy. Foxes taken from a foothill locality west of Davis were
found to harbor the nematode, Spirocerca lupi; coyotes and foxes from this site
harbored the filaroid nematode, Dirofilaria immitis.
Discovery of 5. lupi in foxes is of particular interest because this parasite has
been rarely documented in this host (Buechner 1944, Bailey 1963), and autoch-
thonous cases of spirocercosis have not been previously reported from Califor-
nia. D. immitis, however, is highly endemic in some dog (Walters and
Lavoipierre 1984) and coyote (Weinmann and Garcia 1980, Acevedo and Theis
1982) populations of northern California. Recovery of D. immitis fom coyotes
in this foothill locality may be epidemiologically relevant in light of documenta-
tion of autochthonous D. immitis in domestic dogs of an adjacent community
(Walters et al. 1981 ); coyotes have been considered potential reservoirs of the
parasite to dogs in other rural foci (Gier and Ameel 1959; Monson, Stone and
Weber 1973; Crowell et al. 1978).
MATERIALS AND METHODS
All animals were captured in the Coast Range foothills near Lake Berryessa,
northern California, either in Markley Canyon ( Napa Co. ) or in Pleasants Valley
(Solano Co.). During February 1978-January 1979, 21 animals were necropsied
and examined for helminth parasites. These included 17 gray foxes, Urocyon
cinereoargenteus, and 4 coyotes, Canis latrans. Special attention was paid at
necropsy to the presence of helminths in the alimentary canal, body cavities,
vascular system, lungs, and kidneys. Nematodes were preserved in a 70%
ethanol/glycerol mixture (95 parts/5 parts). Heart blood was examined for
microfilariae of D. immitis by direct smear (coyotes) or by the Difil " method
(foxes).
' Accepted for publication |uly 1985.
' Dr. Lavoipierre deceased 1 Nov. 1984. Send reprint requests to Dr. Walters.
^Current address: Ferndale Veterinary, P.O. Box 1032, Ferndale, CA 95536.
* Current address: Yale University School of Medicine, Dept. Epidemiology and Public Health, P.O. Box 3333, 60
College St., New Haven, CT 06510.
NEMATODE OCCURRENCE IN WILD CANIDS
79
RESULTS
Four of the 1 7 (24%) foxes were found to be infected with 5. lupi ( Figure 1 ) .
In each of the four infected animals, male and female nematodes were found
in granulomas at and posterior to the ileo-colic junction of the ileum and colon.
No gross lesions were recognizable in the thoracic organs. In one case, the
granulomas were so large that they appeared to be causing a stricture of the
colon close to the ileo-colic junction.
I I Q
0.5mm D
0.03mm
0mm
FIGURE 1: A. Anterior end of a female Spirocerca lupi dissected from a granuloma at the ileo-
caecal junction of a gray fox. B. A photograph of three eggs of Spirocerca lupi dissected
out of the uterus of a gravid female worm. C. A schematic view of the anterior end
of a female Spirocerca lupi from a gray fox to show the position of the vulva relative
to the esophagus. Note that the vulva opens far forwards on the body of the nematode.
Be, buccal capsule; I, intestine; Nr, nerve ring; Eg, esophagus-glandular portion; Em,
esophagus-muscular portion; Ut, uterus; Va, vagina; Vu, vulva.
80 CALIFORNIA FISH AND CAME
D. immitis was found in only one of the foxes. Five adult worms (3 females,
2 males) were located in the right ventricle of the heart; circulating microfilariae
were not detected. In three of the four coyotes examined, adult heartworms
were recovered from the right ventricle. Infected animals harbored 94 (44
females, 50 males), 36 (22 females, 14 males), and 23 (9 females, 14 males)
worms; circulating microfilariae were detected in the blood of each infected
coyote.
DISCUSSION
Although the fox, in addition to other carnivores, is known to be a host to 5.
lupi, records of the occurrence, or the possible occurrence, of the worm in this
host in the United States are limited to the reports of Buechner (1944), Bailey
(1963), and Pence and Stone (1978).
In the dog (Bailey 1963, 1972) and the coyote (Smith 1971; Thornton, Bell
and Reardon 1974; Pence and Stone 1978; Morrison and Cier 1979), 5. lupi is
found in the upper alimentary canal (the esophagus) and in the thoracic and
abdominal aorta. In the foxes we examined, however, the nematodes were in
the lower intestine. Likewise, in the only case of fox spirocercosis seen by Bailey
(1963), "The parasites were embedded in nodules in the wall of the colon."
Pence and Stone (1978) recorded aortic lesions resembling those caused by 5.
lupi in one gray and one red fox in an area in Texas where coyotes were infected
by the nematode; no worms however, were recovered from the foxes.
Our discovery of a high proportion of foxes infected with 5. lupi from a
relatively delimited area in the Lake Berryessa hills indicates the presence of an
autochthonous focus of spirocercosis in California. This is interesting since Bailey
(1972) summarizing " . . . information on the prevalence of Sp/rocerca /up/ in
the United States, based on data from necropsy records of U.S. colleges of
veterinary medicine", found that between 1952-1970 some 8,000 dogs were
examined in California and only 3 were found to have spirocercosis. These cases
were considered imported. Several of our clinical colleagues at the Veterinary
Medical Teaching Hospital (VMTH) in Davis (Drs. I. M. Courlay, D. R. Strom-
beck, P. F. Suter) who have had considerable experience with dogs assure us
that they have no familiarity with the disease in this area. A computer search
of the hospital records for the years 1967-79 (Dr. Suter pers comm.) found no
incidence of 5. lupi in the esophagus of dogs presented for treatment at the
VMTH. Spirocercosis, therefore, appears to be non-existent, or very rare in dogs
of northern California. We can only speculate as to the origin of the present
spirocercosis focus in foxes near Lake Berryessa. The area is a popular vacation
spot visited by many dog owners, not only from California but also from out-of-
state, and it is possible that the parasite may have been introduced by a visiting
dog from elsewhere in the United States. At the present time, in many areas of
California, suitable conditions (Bailey 1972) exist for the natural cycling of 5.
lupi. If our experience with dirofilariasis in California (Walters and Lavoipierre
1982, 1984) is any indication of future trends in the epidemiological pattern of
spirocercosis, then more cases may come to light.
The large nur.bers of D. immitis found in the heart of infected coyotes of the
Berryessa area suggests multiple infections of these animals by local mosquito
vectors. Particularly noteworthy was the coyote harboring 94 worms in the
heart, this being the greatest number documented in the United States (Ameel
1955; Cier and Ameel 1959; Monson, Stone and Weber 1973; Graham 1975;
NEMATODE OCCURRENCE IN WILD CANIDS 81
Franson, Jorgenson and Boggess 1976; Kazacos 1977; Crowell et al. 1978; Kaza-
cos and Edberg 1979; Weinmann and Garcia 1980; Custer and Pence 1981).
Whether the prevalence of microfilaremic coyotes in a specific geographic area
reflects the prevalence of dirofilariasis in donnestic dogs, at present, remains
unanswered in California. Acevedo and Theis (1982) have suggested that in
some areas of northern California a sylvatic cycle with urban spillover may be
occurring; however, concurrent studies of dog and coyote populations in specif-
ic localities are generally lacking. In the Pleasants Valley area, the present study
and Acevedo and Theis (1982) have both indicated a high prevalence of heart-
worm infection in coyotes. In domestic dogs of Pleasants Valley, a community-
based survey during 1979 detected only 2/97 (2.1%) microfilaremic animals
( Walters et al. 1 981 ) . Both cases, however, were considered autochthonous and
probably unrelated (dogs resided 5.6 km apart), and therefore, may have result-
ed from mosquito transmission via a coyote reservoir, if wild and domestic
cycles interdigitate. High prevalence of heartworm (21.1-34.3%) in dogs of
other northern California communities (Walters and Lavoipierre 1984) suggests
that the parasite may be maintained in a domestic dog cycle; however, the
contribution of a coyote reservoir in these areas has not been explored.
ACKNOWLEDGMENTS
We are grateful to W. Sievers who trapped all the animals. S. Karr and P.
Budwiser provided valuable assistance in several ways and we extend to them
our thanks. Finally, we are indebted to the Office of the Dean, School of Veteri-
nary Medicine, University of California, at Davis, for a grant, BRSG 79-10, which
assisted us in defraying part of the expenses for this study.
LITERATURE CITED
Acevedo, R. A., and ). H. Theis. 1982. Prevalence of heartv^'orm {Dirofilaria immitis Leidy) in coyotes fronn five
northern California counties. Am. ). Trop. Med. Hyg., 31 (5); 968-972.
Ameel, D. j. 1955. Parasites of the coyote Canis latrans Say, in Kansas, j. Parasitol., 41: 325.
Bailey, W. S. 1963. Parasites and cancer; sarcoma in dogs associated with Spirocerca lupi. Ann. N.Y. Acad. Sci.,
108 (Art. 3): 890-923.
1972. Spirocerca lupi: a continuing inquiry. J. Parasitol., 58: 3-22.
Buechner, H. K. 1944. Helminth parasites of the gray fox. |. Mammot., 25: 185-188.
Crowell, W. A., T. R. Klei, D. I. Hall, N. K. Smith, and ). D. Newsom. 1978. Occurrence of Dirofilaria immitis and
associated pathology in coyotes and foxes from Louisiana. Pages 10-13 in H. C. Morgan, ed. Proceedings of
the heartworm symposium — 1977. VM Publishing Inc., Bonner Springs, Kansas.
Custer, ). W., and D. B. Pence. 1981. Dirofilariasis in wild canids from the gulf coastal prairies of Texas and
Louisiana, U.S.A. Vet. Parasitol., 8: 71-82.
Franson, j. C, R. D. Jorgenson, and E. K. Boggess. 1976. Dirofilariasis in Iowa coyotes. |. Wildl. Dis., 12: 165-166.
Cier, H. T., and D. |. Ameel. 1959. Parasites and diseases of Kansas coyotes. Kans. Agric. Exp. Sta. Bull. 91. 34
P-
Graham, |. M. 1975. Filariasis in coyotes from Kansas and Colorado. ). Parasitol., 61: 513-516.
Kazacos, K. R. 1977. Dirofilaria immitis in wild Canidae from Indiana. Proc. Helminth. Soc. Wash., 44: 233-234.
Kazacos, K. R., and E. O. Edberg. 1979. Dirofilaria immitis infection in foxes and coyotes in Indiana. J. Am. Vet.
Med. Assoc, 175 (9): 909-910.
Monson, R. A., W. B. Stone, and B. L. Weber. 1973. Heartworms in foxes and wild canids in New York. NY. Fish
and Game )., 20(1): 48-53.
Morrison, E. E., and H. T. Cier. 1979. Parasitic infection of Filaroides osleri, Capillaria aerophila and Spirocerca
lupi in coyotes (Canis latrans) from the southwestern USA. ). Wildl. Dis., 15: 557-560.
Pence, D. B., and ). E. Stone. 1978. Visceral lesions in wild carnivores naturally infected with Spirocerca lupi. Vet.
Pathol., 15: 322-331.
Smith, j. P. 1971. Parasitic aortic aneurysms of coyotes. Pages 259-263 in S. M. Gaafar, ed. Pathology of parasitic
diseases. Purdue Univ. Press, Lafayette, Indiana.
82 CALIFORNIA FISH AND CAME
Thornton, J. E., R. R. Bell, and M. ). Reardon. 1974. Internal parasites of coyotes in southern Texas. J. Wildl. Dis.,
10: 232-236.
Walters, L. L., and M. M. J. Lavoipierre. 1982. Aedes vexans and Aedes sierrensis (Diptera: Culicidae): potential
vectors of Dirofilaria immitis in Tehanna County, northern California, USA. J. Med. Entonnol., 19(1): 15-23.
1984. Landscape epidemiology of mosquito-borne canine heartworm {Dirofilaria immitis) in northern
California, USA. I. Community-based surveys of domestic dogs in three landscapes. ). Med. Entomol., 21(1):
1-16.
Walters, L. L., M. M. |. Lavoipierre, K. I. Timm, and S. E. )ahn 1981. Endemicity of Dirofilaria Immitis and
DIpetalonema recondltum in dogs of Pleasants Valley, northern California Amer J Vet. Res., 42(1 ): 151-154.
Welnmann, C. )., and R. Garcia. 1980. Coyotes and canine heartworm In California. ). Wildl. Dis., 16: 217-221.
SPOT PRAWN GROWTH AND REPRODUCTION 83
Calif. Fish and Came 72(2): 83-93 1 986
GROWTH AND REPRODUCTION OF SPOT PRAWNS IN
THE SANTA BARBARA CHANNEL ^
JOHN S. SUNADA
Marine Resources Division
Department of Fish and Game
245 W. Broadway, Suite 350
Long Beach, California 90802
Growth and reproduction studies were conducted on spot prawn, Pandalus
platyceros, taken from commercial landings in Santa Barbara during 1981 through
1983. Maximum age was estimated to be 6 years. Males became mature at age 3,
averaging 40 mm CL, with the transitional stage averaging 45 mm cl and females near
48 mm cl at age 4. Nearly all females were in the ovigerous stage by December. Sex
ratio for 1981-82 season was 2.46 males to one female, but was near a 1:1 ratio in the
1982-63 season.
INTRODUCTION
The spot prawn, Pandalus platyceros, a pandalid found from Alaska to San
Diego, has been described in detail. Much is known about age and growth
(Berkeley 1930, Butler 1964). More recent growth studies were conducted
under laboratory conditions (Kelly, Haseltine, and Ebert 1977). The majority of
these studies were based on data from specimens captured in British Columbia
and Monterey. The Santa Barbara Channel population, located at the southern
range, appears to display a longer longevity and later sexual transformation
(Figure 1). This resource has become a significant fishery in this region, con-
tributing nearly 118,200 kg in 1981, with an ex-vessel value of $524,000. Such
a valuable resource requires proper management. Basic growth and age parame-
ters are essential for deriving population estimates. This study was initiated to
provide data in the development of a management scheme.
METHODS AND MATERIALS
Nearly all of the 4,536 individuals used in this study were measured and sexed
at various fish markets located in Santa Barbara, Ventura, and Terminal Island
(Figure 1 ). Measurements were taken to the nearest mm by means of a vernier
caliper. Carapace length (cl) was determined by measuring from the base of
the eyesocket to the posterior midline of the carapace. Age was determined by
graphing length frequencies and separating modes by a method using probability
paper as described by Harding (1949) and Cassie (1954).
Sexes were determined on location by examination of the second pleopod for
absence or presence of the appendix masculina, a male characteristic. These
prawns are protandric hermaphrodites, undergoing a sex change to females in
later years. A total of 90 individuals was weighed and measured for determining
a length-weight relationship. Weights were recorded to the nearest tenth of a
gram.
Growth rates and parameters were determined by use of the Von Bertalanffy
growth equation using the program BGC2 (Abramson 1971).
Accepted for publication December 1985.
84
CALIFORNIA FISH AND CAME
LEQENO
Spot prawn trawling grounds
Northern Channel Islands
Terminal Islend
FIGURE 1. Location of fish markets and fishing grounds in southern California.
RESULTS
Growth
Designation of a Birthdate
Spot prawns are known to spawn in the fall and incubate their eggs until late
winter. Since the majority of females have shed their eggs by April, and hatching
has most likely occurred, 1 April was designated as the birthdate.
Modal Progression Analysis
Length frequencies taken during the April-May period of 1981 displayed
several modes with a major peak near 40 mm carapace length (Figure 2). This
mode was believed to represent the 1978 year class or age group 3. A second
less pronounced mode occurred near 50 mm cl, representing the 1 977 year class
(age group 4) and a minor peak near 30 mm CL (the 1979 year class or age group
2).
Incremental increases in growth for age group 3 occurred slightly throughout
the year and to a lesser degree, with age group 4. By the January-March period,
numbers of age group 2 animals increased in the catch. These prawns measured
35 mm CL. The prawns taken during the April to May quarter increased in size
to 37 mm CL by 1 April 1982, when they had completed their third year.
SPOT PRAWN GROWTH AND REPRODUCTION
85
10
L. Apr. May 188 1
N=266
% 6
f~
n,r>rrrkTT
ttt
1 - h r-^ j-i
10_ July. Sept 1861
N=621
% sL
n-f-rrf[TK-i-fT
Th^ ,
6..
10i_ Oct-Dec 1881
N=764
n-fhr-n-pl
"h-TK
10 .
5.
Jan. March 1882
^^
N= 388
-
— ^ — ^-. .:....
"hjflTK-ru,
r-
30
40
50
60
Carapace length in mm
FIGURE 2a. Length frequency distribution of spot prawns during 1981 through 1983.
Beginning in the April-June period of 1982, the 1978 year class (now age
group 4) continued to dominate the catch, in addition to the 1977 cohort (age
group 5) (Figure 2). The 1978 year class continued to occur near 45 mm cl
throughout November. During the January-March quarter, the mode became
86
CALIFORNIA FISH AND GAME
less discernable, and merged with older age groups. Age group 3 (1979 year
class) on the contrary, did not dominate the catch during the year as did age
group 3 during the previous year. This age group remained weak until August
10
% 5
Apr-June 1982
Nsr571
.n
T-p^ I
V^np
10
% 5
July-Sept 1982
N= 663
,^.t{TT]T
^^^^ — , —
10 ^
% 5
Oct, Nov 1982
N = 440
rr-r
0;
IL
10^
% 5
J a n-M a r 19 8 3
N = g32
r-rr-rT-i-n-Tl I
T
-p^
30
T
40
60
60
Carapace length In mm
FIGURE 2b. Length frequency distribution of spot prawns during 1981 through 1983.
SPOT PRAWN GROWTH AND REPRODUCTION
87
and the October-November period (Figure 2). During the October-November
period, however, recruitment of prawns from the 1980 year class (age group 2)
began. These animals averaged 30 mm cl. Their presence continued through the
winter, appearing in large numbers during the January-March quarter, and ave-
raging 34 mm cl( Figure 2). Also during this period, prawns from the 1981 year
class in the 21-18 mm CL range began appearing (Figure 2).
Von Bertalanffy Growth Calculation
The monthly modes from April 1981 through March of 1982 were incorporat-
ed in applying the Von Bertalanffy equation, using the computer program BVG2
( Abramson 1 971 ) . A curve was plotted with the following parameters: L oc = 96
mm CL, K =0.1 57 and to = —0.18. The curve fitted well with the observed length
at early ages, although L oc occurred much beyond the observed range (Figure
3). Maximum observed age is estimated at 6+ years. This is at least a year older
than the previously reported maximum age of 5 years (Butler 1964).
70
60
Butler(1964)
VBG curve calculated
from observed lengths
Observed lengths
AQE
FIGURE 3. Observed and VBG-calculated length at age of spot prawns.
88
CALIFORNIA FISH AND CAME
Length-Weight Relationship
Length and weight data in ninety prawns was used to construct a length-
weight curve. Size of the prawns ranged from 22 mm cl to 56 mm CL, while
weights ranged from 8 g to 102 g (Figure 4). When fitted by the formula
W =a L ^ the results were a =0.00142, b =2.786 with a correlation coefficient
of 0.994 (Figure 4).
Carapace length in mm
FIGURE 4. Length-weighl curve for spot prawns taken from Santa Barbara Channel.
Reproduction
Sexual Development and Maturation
Spot prawns like most pandalid shrimps, are protandric hermaphrodites, be-
ginning their lives as males.
SPOT PRAWN GROWTH AND REPRODUCTION 89
Males became sexually mature during their 4th year when they averaged 40
mm CL. By the end of the 4th year (winter and spring) many males began to
change sex into the transitional stage (Figure 5). By summer (5th year) many
of the transitionals became females averaging 45 mm cl, although females as
small as 39 mm cl were observed (Figure 5).
Ovigerous females began to appear in the samples as early as July, although
September appears to be the spawning month as was noted by Butler (1964).
By September over 50% of the females were in the ovigerous stage, reaching
100% by December (Figure 6). Females began shedding the eggs during late
winter. By April only 15% were ovigerous.
Sex Ratio
These animals, being hermaphroditic, created a problem of determining an
appropriate sex ratio. It is expected that males should outnumber females at least
by a ratio of 2:1 , depending on the dynamics of the population. Sex ratios during
the 1981-82 period yielded 2.46 males to 1 female, a reasonable figure, while
ratios derived in 1982-83 period fell to 1.34 males to 1 female (Table 1 ). This
unusual occurrence probably was the result of bias in sampling and gear selectiv-
ity.
DISCUSSION
The difference in age and growth of spot prawns between areas is quite
noticeable. Butler (1964) stated that very few animals from Vancouver lived
longer than 4 years, whereas my results indicate that Santa Barbara prawns reach
6 years old. The growth curve of Santa Barbara prawns, based on the Von
Bertalanffy equation, also shows a larger length at age for older prawns. Growth
rates of the southern stock for the first 3 years follow very closely the results
reported by other researchers (Figure 3). But beyond this age, there appeared
a divergence, for one season 1981-82, which displayed a larger growth curve.
The large variation for 1981-82 data could be attributed to a larger than normal
growth of a single year class. Rasmussen (1953) in discussing growth rates of
deep sea prawn, Pandalus borealis, found that growth rate is dependent upon
temperature. In a temperate environment, shrimp grow faster than in a cold
environment. P. jordani, pink shrimp, also displayed larger size in later ages for
shrimp taken in California when compared with Oregon and Washington speci-
mens (Dahlstrom 1963).
Length at sex has also differed between the northern and southern stocks.
Berkeley (1930) and Butler (1964) in their studies have shown males to mature
at 28-30 mm CL, undergo a transitional stage near 34 mm cl and become females
near 37 mm cl. The southern population underwent changes at a larger size, with
transitional stages occurring near 45 mm cl and becoming females near 50 mm.
Dahlstrom (1963) and Odemar (1964) also observed larger sizes for transition-
als and females (43 mm and 47.5 mm cl, respectively). Sexual transformation
appears to occur at least a year later for these prawns.
Rasmussen (1967) has noted that growth rates will vary according to the
environmental conditions. Perhaps that is the case with the southern stock of
spot prawns.
90
CALIFORNIA FISH AND CAME
5 -
Apr-May 1881
Malaa
Transitional
8 -
Femalaa
10
-
— ->.
6
Jul-Sep 1981 /
\ Ma
ea
5
T 1 1 1—
\
Females
10
Oct-Dec 1981
Malaa
Females
Jan-Mar 1882
Males
Tranaillonal
30
40
60
Females
60
Carapace length In mm
FICURE 5a. Quarterly length frequency distribution by sex of spot prawns during 1981 through
1983.
SPOT PRAWN GROWTH AND REPRODUCTION
91
Apr-Jun 1982
Males
Transitional
6 '
Jul-Sep 1982
Males
Transitional
Females
1 1 1 1 1 r
Oct-Nov 1882
Males
Transitional
Females
Jan-Mar 1983
Transitional
Females
Carapace length in mm
FIGURE 5b. Quarterly length frequency distribution by sex of spot prawns during 1981 through
1983.
92
CALIFORNIA FISH AND CAME
o>^':^ ^ T. -. T. -. -. -. '-.'-. T.
I CT> O O 'T CT>
II
!•— 0^^^i>ff^r^ I^Tj-
00 LO
Q. — — —
E
Q.'
E
CO op
O
c
-c —
5 < ■
> 'ij c .a
o ii iv (V
Z Q ~ "-
^ .0
c
U
c
c
c
a.
1
o
w
M
»-; ^ r^ tv. •—
ro rs r-j ^ 06
u-1 ~^
00 ■>*■
s
CO
O rN
■J; u-i Ul
c —
I — 10000 —
s
o <^
E
o
c
Q.
E
O
c
CO O 'T
r^ — —
— l-M —
in a^
CO r\
E
5
c
I
c >■ aJ ^
Q. "5 c ^
S.-^ >
'o c -i- 5^ P- Ij
° ^ 5 "S ^
i iT IE
Z Q
^ w in
SPOT PRAWN GROWTH AND REPRODUCTION
93
100 _
FIGURE 6. Percent of female spot prawn in ovigerous stage by month.
ACKNOWLEDGMENTS
I wish to thank G. Gaona, M. Wagner, J. Richards, and R. Collins for their help
and cooperation, and C Avants for her typing and editorial skills.
LITERATURE CITED
Abramson, J. ). 1971. Computer programs for fish stock assessments. FAO Fish. Tech. Pap., (1011:154 p.
Berkeley, A. A. 1930. The post-embryonic development of the common pandalids of British Columbia. Contrib.
Canadian Biol., New Series, 6(6):67-163.
Butler, T. H. 1964. Growth reproduction, and distribution of pandalid shrimps in British Columbia. Fish Res. Bd.
Canada )., 21 (6):1403-1452.
Cassie, R. M. 1954. Some uses of probability paper in the analysis of size frequency distributions. Australian ). Mar.
Freshwater Res., 5:513-522.
Dahlstrom, W. 1963. Cruise Report 63-A-1 Prawn. Dept. Fish and Came. Marine Resources Operation:5 p.
Harding, J. P. 1949. The use of probability paper for graphical analysis of polymodal frequency distributions. J. Mar.
Biol. Assoc. U. K., 28:1410153.
Kelly, R. O., A. W. Haseltine, and E. E. Ebert. 1977. Mariculture potential of the spot prawn, Pandalus platyceros
Brandt. Aquaculture, 10:1-16.
Odemar, M. 1964. Cruise Report 64-A-1 Prawn. Dept. Fish & Game, Marine Resources Operations. 4 p.
Rasmussen, B. 1953. On the geographical variations in growth and sexual development of the deep sea prawn
(Pandalus borealis Kr) Fiskeridir Skr. Havunders, 10(3):160 p.
. 1967. Variations in the protandric hermaphroditism of Pandalus borealis. Proceedings of the World
Scientific Conference on the biology and culture of shrimps and prawns. FAO, Fish. Rept., 57 (3 ):1 101-1106.
94 CALIFORNIA FISH AND CAME
Calif. Fish and Came 72 ( 2 ) : 94-98 1 986
FAWN REARING HABITAT OF THE LAKE HOLLOW DEER
HERD, TEHAMA COUNTY, CALIFORNIA
HEATHER ). WELKER
8312 Riata Drive
Redding, California 96002
A four year study was begun in 1980 to identify and describe fawn rearing habitat
of the migratory Lake Hollow deer herd in California. The average home range of
eight fawns was 14.03 ha with home range sizes for male fawns (x = 23 ha) over twice
that of female fawns (x = 11 ha). Thirty-four fawn capture sites and 20 randomly
selected sites were used as the centers for circular vegetation plots. Factor analysis
revealed significant differences between fawn-selected and random plots, with
fawns selecting for higher elevations and areas with taller trees. Seventy-six percent
of the fawn locations occurred in ponderosa pine, Pinus ponderosa, dominated
forests. Key habitat elements occurring in fawn plots include white fir trees, Abies
concolor, gooseberry, Ribes sp., and snowbush, Ceanothus cordulatus, shrubs and
stumps or dead and down logs.
INTRODUCTION
The mule deer, Odocoileus hemionus, is an adaptable cervid occupying at
least 57 of the 60 different vegetation types found west of the 100th meridian
(Wallmo 1981). The Columbian black-tailed subspecies, O. h. columbianus,
occurs along the west coast from southern British Columbia to central California.
Since the late 1950's deer herds in the western United States have shown a
general pattern of decline (Phelps 1976). Because high neonatal fawn mortality
occurs in many populations, unsuitable rearing habitat, as it pertains to fawn
survival, has been suggested as the reason for much of this decline (Salwasser
1976a).
As part of a larger study conducted by the California Department of Fish and
Game, a four year study was begun in 1980 to identify and describe fawn rearing
habitat of the migratory Lake Hollow deer herd in California. Fawn rearing
habitat is defined as the home range, including dropsite, of a fawn during the
first two months of life. Funding, equipment, and manpower for the first two
years of this four year study were supplied by the California Department of Fish
and Game under contract with the Department of Water Resources.
STUDY AREA
The study area was located in Mendocino National Forest in western
Tehama County, 40 km southwest of Red Bluff. Fawn work concentrated on a
10 km ^ area of the summer range of this deer herd. The summer range (mean
elevation: 2135 m) consists of a mixed conifer forest that receives an average
of 153 cm of precipitation annually, most of which is in the form of snow.
Temperatures range from —20.6° to 32.2° C. Topography varies from gentle
slopes to steep canyons of the major and minor drainages. This specific study
area was chosen because of high seasonal deer concentrations and the variety
of habitat types.
The area has a history of multiple use. Recreation, particularly in the form of
hunting, predominates during the fall months. Several major timber cuts have
' Accepted for publication November 1985.
LAKE HOLLOW FAWN REARING HABITAT 95
occurred since 1969. Selective timber cuts prevailed, but clear cutting and re-
seeding techniques also have been used. Sheep grazing dominated the area prior
to 1920, but cattle and horses have utilized the area since.
METHODS
Thirty-four fawns were captured between June 1980 and August 1982. All
fawns were tagged with numbered aluminum ear tags and 16 were fitted with
radio collars (felonies, Mesa, AZ). Fawn capture sites were used as the centers
for circular vegetation plots. A 0.04 ha plot was used, and mature trees vi'ere
recorded by species, number, height, diameter at breast height (dbh) and per-
cent canopy cover. The number of seedlings and saplings were noted according
to species, and the length, diameter, and decay class (Thomas 1979) of dead
and fallen trees were recorded. Using the same center point, a second 0.016 ha
plot was evaluated for slash content, as well as species, stem number and
percent cover of shrubs. Analyses of herbaceous vegetation and estimates of
percent cover of litter, bare ground and rock were made within 1 m^ plots
located at the four cardinal directions inside the edge of the 0.04 ha plot.
Additional data collected included: aspect, elevation, soil type, indicator species,
successional stage (Thomas 1979) and the distance to roads, water, and special
features such as meadow.
Twenty random plots representing available habitat were selected using a grid
and random number table and evaluated in the same manner as fawn selected
plots. Comparisons between random selected and fawn selected sites were used
to identify specific fawn use habitat components. Each habitat component was
examined individually to determine if usage occurred in a clumped, random or
uniform distribution. Factor analysis, as described in the Statistical Package for
the Social Sciences (SPSS 1975), was used to detect important variables for each
individual year and for all three years combined.
RESULTS
Home range data were collected on eight fawns: two in 1980 and six in 1981.
This sample included six females and two males. The fawns were tracked from
their first week after birth to ages ranging from 48 to 98 days. Based on 631
telemetric point locations (17-177 per fawn), the average home range size for
these fawns was 1 4.0 ha ( range = 1 . 1 -26.0 ha ) . The average home range size for
male fawns ( x =23 ha) was over twice that of female fawns ( x =11 ha).
Seventy-six percent of the fawn locations occurred in ponderosa pine domi-
nated forests with Douglas fir, Pseudotsuga menziesi, as a codominant tree.
Fourteen percent of the locations occurred in habitats where Douglas fir was the
principal tree species and seven percent occurred in areas dominated by white
fir. Three percent of the locations were in miscellaneous shrub habitats. Crown
diameters in the forested habitats were mainly 8 to 12 m and almost 48% of the
fawn locations occurred in areas with 20% to 39% crown cover.
From the analysis of 64 variables representing fawn capture sites in all three
years combined, 29 variables produced four main group associations (Table 1 ).
Each variable group is a part of a community where fawns may be expected to
occur.
96
CALIFORNIA FISH AND CAME
TABLE 1. Means and (Standard Deviations) of Important Variables According to Croup for
1980-1982
Croup I Variables
Mature trees Trees/ha Height (m) dbh (m)
Douglas fir 22.8(64.0) 7.8(18.9) .2 (.5)
Sugar pine 19.9(53.2) 8.5(16.8) .2 (.3)
Seedlings /Saplings
Ponderosa pine 41.0 (108.8)
Sugar pine 16.9 (35.0)
Percent
Shrubs Stems/ha canopy
Manzanita 14.7 (48.8) 1.2 (6.0)
Elevation 1795.1 (78.4)
Group II Variables
Percent
Shrubs Stems/ha canopy
Snowberry 275.7 (546.9) .7 (1.3)
Rose 79.0 (303.1) 7.6 (17.6)
Distance to Road (m) 60.2 (135.6)
Croup III Variables
Mature trees Trees /ha Height im) dbh Im)
Incense cedar 19.9(64.8) 5.4(12.2) .1 (.3)
Seedlings/Saplings
White fir 171.3 (363.3)
Incense cedar 52.2 (147.5)
Decay Class Logs/ha Length (m) Diameter (m)
5 7.4(20.0) .6(1.3) .1 (.3)
Croup IV Variables
Seedlings/Saplings Trees/ha
Douglas fir 34.5 (85.0)
Percent
Shrubs Stems/ha canopy
Snowbush 698.5 (1883.1) 7.6 (17.6)
Herbaceous
Phlox 23,235.0 (77,000.0) .7 (.3)
Group I Variables
Sugar Pine — Douglas Fir
Overstory canopy averaged 8.1 m in height and was dominated by sugar pine,
Pinus lambertiana, and Douglas fir trees. Understory consisted largely of sugar
pine and ponderosa pine seedlings and saplings as well as green-leaf nnanzanita,
Arctostaphalos viscida, shrubs. This type of community was found at approxi-
mately 1795 m elevation.
LAKE HOLLOW FAWN REARING HABITAT 97
Group II Variables
Snowberry — Rose
Snowberry, Symphoricarpos albus, and rose, Rosa sp., shrubs were typically
found together in habitats at distances over 60 m from a road.
Group III Variables
Incense Cedar
Overstory was incense cedar, Libocedrus decurrens, and averaged 5.4 m in
height. Young white fir and incense cedar trees formed the understory. Approxi-
mately 7.4 old (decay class 5) logs (Thomas 1979) were found per hectare.
Group IV Variables
Douglas Fir Seedlings and Saplings
Seedlings and saplings of Douglas fir were associated with snowbush shrubs
and the herbaceous plant, phlox, Polemonium californicum.
Fifty-seven variables were used in the analysis comparing random and fawn-
selected plots. Mature trees of all species were significantly (P<0.05, t = 2.65)
taller in fawn-selected plots (n = 34) than in randomly selected plots (n = 20).
This single factor could promote shrub cover on the forest floor, a key element
in fawn plots. Fawns also were found at significantly {P