CAUFORNIAl
FISH-GAME
"COKSKRVATION OF WILDLIFE THROUGH EDUCATION"
California Fish and Game is a journal devoted to the conservation of v/ild-
life. If its contents are reproduced elsev/here, 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 subscriptions must be renewed annually by returning the post-
card enclosed with each October issue.
Please direct correspondence to:
Kenneth A. Hashagen, Jr., Editor
California Fish and Game
1416 Ninth Street
Sacramento, California 95814
129
Ij
0
VOLUME 66
JULY 1980
NUMBER 3
Published Quarterly by
STATE OF CALIFORNIA
THE RESOURCES AGENCY
DEPARTMENT OF FISH AND GAME
—LDA—
130 CALIFORNIA FISH AND CAME
STATE OF CALIFORNIA
EDMUND G. BROWN JR., Governor
THE RESOURCES AGENCY
HUEY D. JOHNSON, Secretary for Resources
FISH AND GAME COMMISSION
SHERMAN CHICKERING, President
San Francisco
ELIZABETH L. VENRICK, Vice President ABEL GALETTI, IVIember
Cardiff Los Angeles
BERGER C. BENSON, Member RAYMOND DASMANN, Member
San Mateo Nevada City
DEPARTMENT OF FISH AND GAME
E. C. FULLERTON, Director
1416 9th Street
Sacramento 95814
CALIFORNIA FISH AND GAME
Editorial Staff
KENNETH A. HASHAGEN, JR., Editor-in-Chief Sacramento
DARLENE A. OSBORNE, Editor for Inland Fishenes Sacramento
RONALD M. JUREK, Editor for Wildlife Sacramento
J. R. RAYMOND ALLY, Editor for Manne Resources Long Beach
DAVID A. HOOPAUGH, Editor for Salmon pnd Steelhead Sacramento
DONALD E. STEVENS, Editor for Striped Bass, Sturgeon, and Shad Stockton
KIM McCLENEGHAN, Editor for Environmental Services ' Rancho Cordova
CONTENTS
131
Page
Impact of Florida Largemouth Bass, Micropterus salmoides
floridanus. Introductions at Selected Northern California
Waters, With a Discussion of the Use of Meristics for De-
tecting Introgression and for Classifying Individual Fish of
Intergraded Populations Ronald J. Pelznnan 133
Exploitation, Natural Mortality, and Survival of Smallnnouth
Bass and Largemouth Bass in Shasta Lake, California
William F. Van Woert 163
Diet and Behavioral Aspects of the Wolf-Eel, Anarrhichthys
ocellatus, on Sandy Bottom in Monterey Bay, California ..
Larry W. FHulberg and Patsy Graber 172
Decline of the Lake Greenhaven Sacramento Perch
Population C. David Vanicek 178
Notes
A Population of the Endangered Santa Cruz Long-Toed Sala-
mander, Ambystoma macrodactylum croceum, from Mon-
terey County, California Larry G. Talent and Carline L. Talent 184
Repeat Spawning of Pacific Lamprey John H. Michael, Jr. 186
A Diver-Operated Snagging Device for Capturing Lingcod,
Ophiodon elongatus James L. Houk 187
Karyotype of the Sacramento Perch, Archoplites interruptus
Craig A. Busack and Gary H. Thorgaard 189
Book Reviews 192
ERRATUM
Lesh, E. W. 1980. A head-off method of measuring chinook and coho
salmon. Calif. Fish Game, 66(1) : 59-62.
Page 60, 61. The coefficient of deterrpination should be (r^).
Page 61. The ordinate of Figure 3 should read: Fork length v^ith head off
in millimetres.
The abscissa of Figure 3 should read: Fork length with head on in mil-
limetres.
132 CALIFORNIA FISH AND GAME
IN MEMORIAM
J. BRUCE KIMSEY
J. Bruce Kimsey was born in Portland, Oregon on 18 July 1921 and died on 24
January 1980 at the Kaiser Hospital in Sacramento after a lengthy illness. Bruce
leaves a wife and two grown sons and a legacy of devotion to his family and his
career. He had a long and productive career as a professional biologist in fisheries
research and management that spanned about 32 years.
Bruce received a B.A. degree from Chico State University in 1948 and an M.A.
degree from the University of California at Berkeley in 1951. He served with the
Armed Forces in the South Pacific during World War II. His first permanent
position in fisheries was with the California Department of Fish and Game as a
Junior Aquatic Biologist in 1948.
Bruce had wide ranging responsibilities with the Department on matters con-
cerning inland fisheries. Probably the most challenging position during the 13
years he worked for the Department was as a leader of statewide warmwater
fisheries coordination and research. It was during this period that most of his
publications appeared.
His publications numbered about 45. Most appeared in either California Fish
and Game or the Inland Fisheries Administrative Report series. Bruce's interest
and enthusiasm for all aspects of natural history were reflected in his publications,
some which concerned birds and appeared in the Condor.
Bruce's expertise in fisheries matters led to a long involvement and much
overseas travel as a consultant for a number of foreign aid organizations. Bruce
and his family spent an entire year at Lakes George and Edward in Uganda on
an assessment of the fish stocks plus the training of African fisheries workers. This
was just the begining and throughout the remainder of his career, Bruce took part
in numerous short-term overseas assignments. Besides Uganda, Bruce traveled to
Kenya, Tanzania, Rhodesia, Cameroon, Brazil, Colombia, El Salvador, Nicaragua,
Philippines, and Indonesia.
After leaving the Department in 1961, Bruce went to work for the old U. S.
Bureau of Commercial Fisheries as leader of a shrimp research project with
headquarters at Galveston, Texas. He later moved to the Bureau's main office in
Washington, D.C. where he assessed fisheries developments in various countries
around the world. He transferred in 1 961 to the old U. S. Bureau of Sport Fisheries
and Wildlife where he became Chief of the Branch of Ecosystem Research. In this
capacity he supervised six laboratories engaged in reservoir and marine sportfish
research. Bruce returned to Sacramento in 1971 where he assumed the position
of Regional Environmental Quality Officer for the Mid-Pacific Region of the Water
and Power Resources Service. He remained at this post until he died.
Bruce was a fellow of the American Institute of Fishery Research Biologists and
a member of various honorary and professional societies. He was President of the
California-Nevada Chapter of the American Fisheries Society in 1976 and served
as chairman or member of numerous national and regional committees of this
organization.
Bruce will be sorely missed by his many friends and co-workers from around
the world. — Almo J. Cordone
FLORIDA LARGEMOUTH BASS ELECTROPHORETIC STUDIES 133
Calif. Fish and Game 66 ( 3 ) : 1 33-1 62
IMPACT OF FLORIDA LARGEMOUTH BASS, MICROP-
TERUS SALMOIDES FLORIDANUS, INTRODUCTIONS AT
SELECTED NORTHERN CALIFORNIA WATERS WITH A
DISCUSSION OF THE USE OF MERISTICS FOR DETECTING
INTROGRESSION AND FOR CLASSIFYING INDIVIDUAL
FISH OF INTERGRADED POPULATIONS ^
RONALD J. PELZMAN
California Department of Fish and Game
Inland Fisheries Branch
1701 Nimbus Road
Rancho Cordova, CA 95670
Florida largemouth bass, Micropterus salmoides floridanus, had a notable genetic
impact following their introduction into five northern California waters containing
northern largemouth bass, M. s. salmoides, populations: Folsom Lake, New Hogan
Reservoir, Lake Amador, Lake Isabella, and Clear Lake. Analysis of malate dehy-
drogenase isozyme patterns of fish systematically collected in years subsequent to
the introduction indicated that intergraded populations developed at each of the
waters. Incidence of the Florida allele at the study waters, based on malate dehy-
drogenase analyses, eventually ranged from 0.35 at Lake Amador to 0.52 at both New
Hogan Reservoir and Clear Lake.
Discriminant function analysis of meristic data for fish of known electrophoretic
phenotype showed that meristic values were not reliable for classifying individual
fish from mixed populations as to Florida, northern, or hybrid bass categories. This
was supported by meristic data for known F-, hybrids. Hybridization could not
necessarily be detected by an increase in mean meristic value or by unimodality of
a frequency distribution of meristic values. The mode value of lateral line scale
counts appeared to be the best meristic indicator of hybridization.
Information from this study and from a similar study at southern California waters
indicates that introductions of Florida bass into northern bass populations have
generally been beneficial through reducing high exploitation rates, increasing the
mean size of bass in the catch, and providing exceptional fishing for trophy-sized
bass at some waters.
Results of this study indicate that current largemouth bass populations at the study
waters possess a wider spectrum of performance capabilities through the inclusion
of desirable traits attributed to Florida bass. This is particularly advantageous in the
reservoir setting where heavy angling pressure, water level manipulation, competi-
tion of prey species with small bass, and other factors work against the maintenance
of a bass population.
TABLE OF CONTENTS
Page
ABSTRACT 133
INTRODUCTION 134
METHODS AND MATERIALS 138
RESULTS AND DISCUSSION 141
Electrophoretic Analysis — Malate Dehydrogenase 141
Frequency of the Florida Allele Based on Malate Dehydrogenase
' This work was performed as part of Dingell-Johnson Project F-18-R, "Coldwater Reservoir and Special Experi-
mental Reservoir Program," supported by Federal Aid to Fish Restoration funds. Accepted for publication.
134 CALIFORNIA FISH AND GAME
Analyses 144
Electrophoretic Analysis — Tetrazolium Oxidase 147
Meristic Analysis 148
Use of Meristic Data in Evaluating Study Populations 151
Population Sampling 154
Rancho Seco Reservoir 155
Maladaptive Genes 156
Performance Capabilities of Fish of Intergraded Populations 157
Management Implications 158
ACKNOWLEDGMENTS 160
REFERENCES 160
INTRODUCTION
Northern largemouth bass were widely distributed to California's low- and
mid-elevation waters in the years following their introduction from Quincy,
Illinois^ in 1891 (Shebley 1917). Florida largemouth bass were not introduced
until 1959 when about 20,400 fingeriings from Holt State Fish FHatchery, Pen-
sacola, Florida were liberated at Upper Otay Reservoir, San Diego County,
which had been chemically treated to eradicate all fish and closed to public
access (Sasaki 1961). These fish and their progeny were stocked at many
southern California waters under the concept that Florida bass superiority in
growth rate and longevity and possible lower vulnerability to angling would
provide bass stocks with more large fish than northern bass were providing.
While Florida bass were stocked into northern bass populations at most of these
waters, Lake Hodges, San Diego County, which served as a source for some
Florida bass plants in northern California, was dewatered and chemically treated
prior to receiving Upper Otay fish in 1969 (L. Bottroff, Fishery Biologist, Calif.
Dept. Fish and Game, pers. commun.).
Florida bass were first stocked in northern California (that portion of California
north of the Tehachapi Mountains) in April 1969 at Clear Lake and Hidden
Valley Reservoir, both in Lake County, from Upper Otay Reservoir (R. Wood,
Fishery Biologist, Calif. Dept. Fish and Game, pers. commun.). Northern bass
were present at Clear Lake, while newly impounded Hidden Valley Reservoir
was devoid of bass at the time the introductions were made. From 1970 through
1973, Florida bass were stocked at a limited number of northern California
waters containing northern bass of Illinois origin, including the five waters exam-
ined by this study ( Figure 1 ) . During that period, Florida bass were also stocked
at a small number of waters that were devoid of bass including a farm pond in
the San Joaquin Valley and Rancho Seco Reservoir, Sacramento County. These
two waters served as sources for plants made later at the study waters (Figure
1).
The largemouth bass present at the study waters were considered descendants
of northern bass brought to California from the northern part of their range in
the United States. Based on a review of fish stocking records and communica-
tions with knowledgeable hatchery personnel and fishery biologists, northern
' The earliest documentation of largemouth bass shipments into California gives 1891 as the year of introduction
(Shebley 1917). According to Shebley the United States Commission brought largemouth bass and warmouth
"bass" here for stocking at Lake Cuyamaca and the Feather River. While the source for largemouth bass is
not given it was very likely Quincy, Illinois since this is given as the warmouth "bass" source.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES
135
HOLT HATCHERY
PENSACOLA, FL.
1959
■^969-
UPPER OTAY
RESERVOIR
1972
1973
RANCHOSECG
RESERVOIR
REGION 4^
FARM POND
HIDDEN
VALLEY
RESERVOIR
1970
1971
FOLSOM
LAKE
LAKE
AMADOR
HOGAN
RESERVOIR
LAKE
ISABELLA
1969
u
CLEAR
LAKE
FIGURE 1. History of Florida largemouth bass stocking as related to the study waters (1-5).^
Region 4 is one of six geographical areas of California designated by the Department
for administrative and mangement purposes. It includes largely the San Joaquin Valley
and adjacent foothills.
bass from other portions of their range were not stocked at the five study waters
prior to the period of this study.
Apparent intolerance of Florida bass to 4°C in Missouri (Johnson 1975) and
concern that maladaptive genes possibly related to this intolerance would be
transmitted to northern bass populations (Childers 1975), prompted the Depart-
ment to establish a moratorium in May 1974 on further stockings of the subspe-
cies in northern California. Consequently, this study was initiated in July 1975 to
evaluate the survival and genetic impact of Florida bass at northern California
waters. Largemouth bass populations at Folsom Lake, Sacrdmento County; New
Hogan Reservoir, Calaveras County; Lake Amador, Amador County; Clear Lake,
Lake County; and Lake Isabella, Kern County were selected for evaluation. The
largemouth bass population at Rancho Seco Reservoir was also analyzed since
it served as a source for Florida bass plants at four of the study waters.
Identification of Florida and northern largemouth bass and their hybrids was
critical to evaluating mixed populations at the study waters. Bailey and Hubbs
( 1 949 ) first used scale counts for separation. Workers since have counted scales,
pyloric caeca, and vertebrae, and made body measurements (Bottroff 1967;
Buchanan 1968; Bryan 1969; Addison and Spencer 1971; Buchanan 1973; Chew
1975; Johnson 1975; and Bottroff and Lembeck 1978).
136 CALIFORNIA FISH AND CAME
Physiological differences between Florida and northern largennouth bass were
reported by Hart (1952). Bryan (1964) noted differences between serum elec-
tropherograms of the two subspecies. Differences in the electrophoretic mobility
of isozymes (different molecular forms of enzymes) from tissues of largemouth
and smallmouth bass and their hybrids were described by Whitt, Childers, and
Wheat (1971). Chew (1975) reported that Dr. William Childers of the Illinois
Natural History Survey, Urbana, Illinois, was able to separate Florida bass,
northern bass, and fish thought to be their hybrids by isozyme analysis. Childers
( pers. commun. ) utilized starch gel electrophoresis and separated the fish on the
basis of their different isozyme patterns of the enzyme malate dehydrogenase
(MDH).
As related to this study, gel electrophoresis is a method for observing genetic
variation of mixed populations by examining variant proteins (isozymes) manu-
factured by different individuals. A tissue sample from each individual to be
studied is homogenized to release its cell contents, including isozymes. These
are introduced into a gel made of starch and subjected to an electric current for
a few hours. Each isozyme in the sample migrates through the gel in a direction
and a rate that depends primarily on its net electric charge and, to some extent,
on its molecular size and conformation. The gel is then treated with a solution
containing a specific substrate, which is cleaved by the enzyme to be observed,
and a salt, which couples with the cleavage products. This process yields a
colored band at the zone to which the enzyme has migrated.
Because isozymes that are specified by different alleles may have different
molecular structures and charges (and hence different mobilities in an electric
field), the genetic makeup at the gene locus coding for a given enzyme can be
established for each individual from the number and position of the electropho-
retic bands (Ayala 1978). The advantage of data obtained through gel electro-
phoresis is that genetic interpretations can be made directly. Most variant alleles
show codominant expression. This permits designation of the genotypes of
individual samples based on staining patterns (Utter, Hodgins, and Allendorf
1 974) . When animals are crossed that are homozygous for different codominant
alleles at the same locus, their offspring are heterozygous, receiving one allele
from each parent. Because each allele codes for a slightly different protein,
heterozygosity can be inferred from the presence of two variants of a given
protein in a single individual (Ayala 1 978) . The simplest form of diploid variation
is when two codominant alleles are present in a population, one specifying a
fast-moving band and the other a slow-moving band. An individual homozygous
for either allele will show a single band, whereas the heterozygote will have both
bands (Gottlieb 1971).
Childers (pers. commun.) found that the MDH isozyme patterns (pheno-
types) of Florida largemouth bass and northern largemouth bass (from the
northern part of their geographic range) differed (Figure 2). Florida bass and
northern bass were both homozygous for supernatant MDH-A and MDH-B.
However, because of mutational differences in the makeup of the B gene locus,
the most anodal band (B„ B„,; m == fast) of the Florida bass showed greater
mobility than the most anodal band (B, B^; s = slow) of northern bass (Figure
2). The A gene locus and B gene locus of the northern bass each code for the
production of a different subunit (A and B^, respectively). These translated
subunits randomly combine to form the various dimers which will migrate
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES
137
through starch gel differing distances in response to an electric current to pro-
duce a three-banded pattern. The Florida bass pattern is similarly produced by
an A gene locus and a B gene locus, each coding for the production of a different
subunit (A and B„, respectively). When northern and Florida bass are crossed
the genotype AA B„B. translates subunits that randomly combine to form six
dimers (AA, AB„ B,B., AB„, B„B„ and B„B„). This appears as a five-banded
pattern, hov^ever, since two dimers (B,B, and ABn,) migrate the same distance
in starch gel. The F, hybrid shows all bands found in Florida and northern bass
plus an additional band ( B„BJ . For discussion of MDH phenotypes, MM is used
for Florida bass, SS for northern bass, and MS for the hybrid.
[ NORTHERN
I UARGEMOUTH
BASS
FLORIDA LARGEMOUTH BASS
F, HYBRID
FIGURE 2. Malate dehydrogenase and tetrazolium oxidase phenotypes of northern and Florida
largemouth bass and their F, hybrid. ' Results from study waters showed all MS fish
by MDH pattern to show only MM or MS by TO.
The frequency of alleles in a given population can be measured by direct
counts from the electrophoretic expression of a representative sample (Utter
and Allendorf 1977). In this study, the number of M alleles (coding for the B„B„
band) and S alleles (coding for the 83, band) in a population was determined
(see Figure 3 for example). The number of MDhI genes in a particular collection
is twice the number of individuals sampled because a complementary pair of
MDH genes are coded in each individual. A homozygous individual codes in
duplicate for a given allelic form and the heterozygous individual codes for two
different allelic forms.
Childers (pers. commun.) used an additional enzyme system, tetrazolium
oxidase (TO), which permitted partial separation of Florida and northern bass
(Figure 2). He found that northern bass were homozygous, showing a single
138
CALIFORNIA FISH AND CAME
fast-moving band (MM), whereas Florida bass showed either the fast-moving
band (MM), or a single slow-moving band (SS), or a heterozygous three band-
ed pattern (MM, MS, and SS). Fish thought to be first filial generation hybrids
between Florida and northern bass showed the MM or MS pattern. Tetrazolium
oxidase was used in this study to provide supportive data.
PHENOTYPE
SS
MS
MM
NO. OF FISH
SHOWING
PHENOTYPE
25
50
25
NO. OF FLORIDA
BASS ALLELES
IN SAMPLE
2X25^=^50
Wms
100
NO. OF NORTHERN
BASS ALLELES
IN SAMPLE
2X253=50
"■ 50n,s
100
FREQUENCY OF
FLORIDA
ALLELE (M)
^00=0.50
200
FREQUENCY OF
NORTHERN
ALLELE (S)
100 -0.50
200
FIGURE 3. Calculation of gene frequency for a collection of 100 fish composed of 25 fish showing
the SS phenotype, 50 showing the MS phenotype, and 25 showing the MM pheno-
type.
METHODS AND MATERIALS
Fish from purportedly pure California sources of Florida bass ( Upper Otay and
Hidden Valley reservoirs) and northern bass (Central Valleys Warmwater
Hatchery, Sacramento County; Shasta Lake, Shasta County; and Merle Collins
Reservoir, Yuba County) were examined meristically and electrophoretically.
Results for fish from Central Valleys Warmwater Hatchery were of particular
interest. This hatchery had been involved for many years with stocking northern
FLORIDA LARGEMOUTH BASS ELECTROPHORETIC STUDIES 139
largemouth bass at northern California waters, including Folsom Lake, New
Hogan Reservoir, and Lake Amador ( M. Cochran, Fish Hatchery Manager, Calif.
Dept. Fish and Game, pers. commun.). Also, hatchery brood fish had been
obtained from several northern California sources.
Fish from mixed populations were analyzed using meristic and electrophoretic
information for pure populations as baseline data. The study plan was to assess
the degree of hybridization of Florida and northern bass by analyzing 100
young-of-the-year bass from each of the study waters annually. Electrophoresis
was the primary method used; however, since no largemouth bass study involv-
ing both meristic and electrophoretic evaluations of the same fish was found in
the literature, meristic data were collected through 1977 for fish analyzed elec-
trophoretically. This provided a means to assess the value of meristic data for
classifying individual fish from mixed populations and to determine if meristics
could be used by fishery managers in their assessment of the degree of hybridiza-
tion of mixed populations.
Fish were collected by electroshocking each fall from 1975 through 1978. So
that samples would be representative of populations being evaluated, collections
were made using the following guidelines:
(1 ) Sample at each of the four major compass directions.
(2) Sample representative cover types.
(3) Collect young-of-the-year of all sizes.
(4) Collect no more than 10 fish when encountering heavy concentrations
of fish such as at the apex of coves, in brushy areas, etc.
Fish were sacrificed, individually enclosed in plastic bags, and transported in
crushed ice to prevent breakdown of enzyme systems. At the laboratory they
were retained in ice until each received an identifying tag and tissue was
removed for analysis. When time did not permit this, fish were frozen and later
thawed a few at a time for processing. Skeletal muscle tissue, used for MDFH,
was removed from an area just below the dorsal fin on the right side of the fish
to facilitate scale counts. Liver tissue was taken for TO analysis. All utensils and
the worker's hands were thoroughly cleaned after each fish was processed. Each
fish and all samples removed from it received an identifying code which includ-
ed information as to the year and water of collection. For example, F-lll-1 was
the first fish of the third year of collection at Folsom Lake, and F-lll-2 was the
second fish, etc. Tissue samples were frozen separately in vials until analysis
could be made.
In some cases older fish were used and information from them was back-
logged to their year of birth based on scale analysis. Use of older fish was
generally avoided, however, because of possible differential survival and was
done only to provide information for years prior to 1975 or to provide samples
for years when drought conditions, scarcity of fish, or other factors limited or
prevented collection of young-of-the-year fish.
Meristic data were collected following procedures outlined by FHubbs and
Lagler (1949). The six counts made included the number of 1 ) scales along the
lateral line, 2) scale rows above the lateral line, 3) scale rows below the lateral
line, 4) scale rows around the caudal peduncle, 5) scale rows on the cheek, and
6) pyloric caeca. A pointer was used for making scale counts. A dissecting scope
was used for counts on small fish. In most cases individual scale counts were
made twice and if they were the same the value was accepted. If they were not
140 CALIFORNIA FISH AND CAME
identical an additional count was made and the dominant value was used.
Pyloric caeca were counted once.
Each tissue sample was thawed to permit removal of a small portion which
was homogenized in two volumes of 0.1 M tris-HCl at pH 7.0 in a "Thomas"
homogenizer for 6 to 10 s using a variable speed electric drill. The sample was
then centrifuged for 20 minutes in a "Sorvall Superspeed RC 2-B "refrigerated
centrifuge at 48,000 X g at 4°C. The supernatant was removed and held at 4°C
until analysis was completed. The homogenizer and utensils were thoroughly
cleaned after each sample.
A tris-citrate pH 6.8 stock buffer of 0.75 tris-(hydroxymethyl)aminomethane
and 0.25 M citric acid (monohydrate) was diluted 1:30 for the gel and 1:7 for
the electrodes. In preparing the gel, 195 ml of buffer was brought to a boil, and
added to a solution composed of 30 g of potato starch and 55 ml of the same
buffer. All air bubbles were extracted with vacuum drain by a waterjet aspirator
and the warm solution was poured into a plastic frame (21.0 cm X 12.2 cm X
0.7 cm) positioned on a flat glass plate slightly larger in area. When the gel had
cooled the frame was removed and plastic strips, half the thickness of the gel,
were placed along each side of the gel. A length of monofilament line was placed
tightly across the strips and drawn through the length of the gel, slicing it into
equal layers. The upper layer could then be discarded or carefully positioned on
another glass plate to provide two gels.
A small piece of filter paper was wetted with the supernatant sample and
implanted in the gel. Up to 20 samples were implanted along a straight line 7
cm from one end of the gel, spaced far enough apart to prevent contamination.
Utensils were thoroughly cleaned between implants. The gel was then covered
with plastic wrap to prevent drying, except for an area about 2 cm wide along
each end.
The gel was placed horizontally in an electrophoresis chamber such that the
portion containing the samples was nearest the cathodal end of the chamber.
The chamber was constructed of plastic and included reservoirs along opposite
ends. Each of these contained a platinum wire electrode along its length and
150-200 ml of tris-citrate bridge buffer at pH 6.8. A nonwoven towel (made by
"Masslinn") served as a wick and electrical conductor from reservoir to gel.
Each wick was drawn up onto the gel to cover that portion of the gel not covered
by plastic wrap. The wicks were also covered with plastic wrap. The chamber
was then placed into a refrigerator and connected to a regulated power supply.
The gel was subjected to 200-VDC (9.5V/cm) for 10 h at 4°C.
The zones of isozyme activity were stained for identification using 100 ml of
tris-citrate buffer (Trizma 0.03 M and citric acid 0.005 M) at pH 8.5, 20 ml of
malate-NaOH at pH 7.0 (0.5 M), 5 mg of nicotinamide adenine dinucleotide,
5 mg of nitro blue tetrazoiium, and 3 mg of phenazine methosulfate. The gel was
covered with this solution and incubated in the dark at 37°C until the banding
patterns were interpretable. It was then rinsed with water and fixed with a
solution of water (five volumes), methanol (four volumes), and acetic acid
(one volume) to facilitate handling.
The procedure for tetrazoiium oxidase was identical to that used for malate
dehydrogenase with the exception of a different stain solution of 100 ml of 0.5
M tris-HCl at pH 9.0, 15 mg of nitro blue tetrazoiium, and 15 mg of phenazine
methosulfate.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES 141
Isozyme patterns of fish collected annually at the study waters were used to
interpret the genetic impact of Florida bass. Presence of the MS pattern in a
population indicated that hybridization had occurred, and the frequency of the
Florida allele in a population indicated the extent of genetic influence of Florida
bass on that population.
Reciprocal crosses of single pairs of Florida and northern largemouth bass
were made in tanks at the Department's experimental management facility
(Field Station) in Sacramento in spring 1978. This was done to confirm the
isozyme pattern (MS) of suspected hybrids from mixed populations, to obtain
meristic data for F, hybrids, and to eventually determine the frequency of iso-
zyme patterns resulting from crosses of F, hybrids, and from backcrosses.
Meristic data for fish of known electrophoretic phenotype were statistically
analyzed to determine if individual fish could be assigned to Florida bass, north-
ern bass, or hybrid categories on the basis of five different scale counts and
pyloric caeca counts. Group membership was examined using discriminant
function analysis. This method finds an axis so that when the original variables
are projected onto this new axis there will be minimum overlap of the groups.
Grouping by electrophoretic pattern and using meristic measures as variables
enabled an evaluation of the usefulness of meristics as group discriminators.
Also, a stepwise procedure determined an economic subset of these measures.
Inclusion into the subset was determined by an F-statistic based on a one-way
analysis of variance test ( Afifi and Azen 1 972 ) . The stepwise discriminant func-
tion analysis was an unmodified Biomedical Computer Program-BMD07M
( Dixon 1 976) . The program generates posterior probabilities for group member-
ship. Prior probabilities for each group member were determined to be the
fraction the group represented of the total sample. The first two canonical
variables for each group were plotted to display the relationships of the groups.
RESULTS AND DISCUSSION
Electrophoretic Analysis-Malate Dehydrogenase
All largemouth bass electrophoretically analyzed from Upper Otay Reservoir
(69 fish) and Hidden Valley Reservoir (114 fish) showed the MM phenotype.
All bass from Central Valleys Warmwater FHatchery (100 fish). Merle Collins
Reservoir (117 fish), and Shasta Lake (73 fish) showed the SS phenotype.
Isozyme patterns for fish from these sources were consistent irrespective of the
size of fish analyzed; larval fish provided patterns identical to those for fish
weighing over 2.3 kg.
Known F, hybrids from reciprocal crosses of Florida and northern largemouth
bass all showed the MS phenotype (Figure 4).
Fish of the MS phenotype appeared in collections from year classes spawned
1 year after the introduction of Florida bass at Folsom Lake and Clear Lake
(Figures 5 and 9). Similarly, hybrid patterns were found within 2 years at Lake
Isabella (Figure 8), within 3 years at New Hogan Reservoir (Figure 6), and
within 4 years at Lake Amador (Figure 7). By 1975, fish of the MS phenotype
were well represented in collections from all study waters. In 1978, the final year
of the study, fish showing the MS phenotype constituted over 44% of collections
from each of the study waters (Figures 5 through 9).
142
CALIFORNIA FISH AND CAME
NORTHERN f
FLORIDA i
Fi HYBRIDS
MDH
PATTERN
S/S
M/M
ALL M/S
NO. OF
LATERAL
LINE
SCALES
65
68
66, 68,65,67 64,66,68,66,64,68,
65,66,67 64,69,65,62,66,66,67,
67 68,68,65,69,63,63,66,65,71,
70,58,65,60,61,58,66
^=65.4
RANGES
58-71
n=37
GRAND
MEAN=
65.7^
RANdE=
58-72^
N=53^
NO. OF
LATERAL
LINE
SCALES
63
72
65,66,66,63,6771,66,6766, 67
67, 69,69,59, 60, 72,46^47^
52i^
X=66.2^
RANGE =
59 - 72^
n=162^
MDH
PATTERN
S/S
M/M
ALL M/S
NORTHERN (i
FLORIDA ?
Fi HYBRIDS
FICURE 4. Malate dehydrogenase phenotype and lateral line scale counts for F, hybrids from
reciprocal crosses of northern and Florida largemouth bass. ^ Abnormally low
counts. ^ Does not include low counts.
FREQUENCY OF
FLORIDA ALLELE
048
LEGEND
oS Mo- MM
% FISH BY PATTERN
NO. OF FISH BY PATTERN
NO. OF FISH ANALYZED
YEARISI OF COLLECTION-AGE
subscript = no. collected
YEAR CLASS
1972
2 0
1976-3 +
1973
19
24
1976-2 +
1974
W
0.39 a42 044
fts
A
^
18 3
25
1975j-0+
1977,^-2+
1975
15
35
46
14
95
1976-0 +
1976
KJei
t«
6 28
146
1977-0 +
1977
m
256312
M
100
1978-1+
1978
FIGURE 5. Results of malate dehydrogenase analyses of fish from Folsom Lake.
Results indicate that Florida bass survived and had an impact at each of the
study waters. Fish shov^ing the MS or MM pattern made up no less than 32%
(Clear Lake — 1975) and as much as 91% (New Hogan Reservoir — 1977) of
collections made from 1975 through 1978. Of 1,767 fish examined during this
period, 1,168 (66%) showed the MS or MM pattern (Figures 5 through 9).
Fish showing the MS pattern only, made up no less than 1 0% ( Lake Isabella —
1976) and as much as 63% (Folsom Reservoir— 1978; Lake Isabella— 1978) of
individual collections. Of 1,767 fish analyzed, 783 (44%) showed the hybrid
pattern. The actual number of hybrid fish included in individual collections.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES
143
however, likely exceeded the number of fish showing the MS pattern. According
to Childers ( pers. commun. ) the offspring of a cross of two MS fish should show
SS, MS, and MM patterns at a 1 :2:1 ratio, respectively. A cross of MS and SS fish
should yield fish showing MS and SS patterns at a 1 :1 ratio. Similarly, MS crossed
with MM should yield MS and MM at a 1 :1 ratio. For this reason it is impossible
to ascertain the incidence of hybrid fish in a population beyond the F, genera-
tion. Hybrid fish from subsequent generations may show an SS, MS, or MM
pattern; results presented in Figures 5 through 9 almost surely include hybrid fish
among those reported as SS or MM.
Collections of bass from Rancho Seco Reservoir, thought to contain a pure
population of Florida bass, consistently contained fish of the MS phenotype. One
fish, a member of the 1973 year class, was of the SS phenotype (Figure 10).
FREQUENCY OF
FLORIDA ALLELE
LEGEND
88 MS MM
% FISH BY PATTERN
NQ OF FISH BY PATTERN
1 1
NO. OF FISH ANALYZED
YEARISl OF COLLECT ION -AGE
subscript -no. collected
YEAR CLASS
1971
1 1
4|0| 1
5
1975^ 2 +
19763-3 +
1972
1973
20| 8| 1
29
1975,,
1974
0.65 0.64 0.70 0.52
49
32
101726
53
1975,j 0+
19766 . 1+
1975
42
43
19 51 52
122
1976 0 +
1976
42
9 42 49
100
1977 0 +
1977
54
W\
ISi
22 57 27
106
1978-0-1
1978
FLORIDA BASS PLANTS
■iil^t: 1 \_±tn 1 T973
1
FIRST SPAWN
..--.
FIRST SPAWN OF PROGENY
-■"■-'.•■■■!
1 1
I;;::;::::::]
FIGURE 6. Results of malate dehydrogenase analyses of fish from New Hogan Reservoir.
0.39 0.33 0.37 0.35
FREQUENCY OF
FLORIDA ALLELE
LEGEND
SS MS Ml
FLORIDA BAS.S PI awTS
FIRST SPAWN
FIRST SPAWN OF PROGENY
^
FLORIDA BASS PLANT
% FISH BY PATTERN
NO OF FISH BY PATTERN
1 1
NO. OF FISH ANALYZED
YEARISl OF COL LECTION -AGE
YEAR CLASS
1970
1971
1972
1 1
7|lo| 1
18
i9;;-3«-
1973
1974
21 29 8
58
1975
26|24[7
57
1976
446213
119
1977
t&T6
1973
JI:
FIGURE 7. Results of malate dehydrogenase analyses of fish from Lake Amador.
^
isi
515515
121
1978
144
CALIFORNIA FISH AND GAME
FREQUENCY OF
FLORIDA ALLELE
LEGEND
^«S MM
%FISH BY PATTERN
NO. OF FISH BY PATTERN
1 1
NO. OF FISH ANALYZED
YEARISI OF COLLECTION -AGE
YEAR CLASS
1972
8 0 10
18
1976-}+
1973
T[5TT
14
1976-2+
1974
0.43
20|12|14
46
1976-1+
1975
0.33
29
3a(6|l7
61
1976-0+
1976
0.41
^
n
54|49|29
132
1977-0+
1977
0.51
»
m
m
13 2714
54^
1979-1+
1978
FLORIDA BASS PLANTS
l-.i.i«7i:--:1 [ ia7.T 1
FIRST SPAWN
■■••-'•"-•■.•.■.■.•j.i \ — =1
FIRST SPAWN OF PROGENY
[■^^
•^^^1 ^^ 1
FIGURE 8. Results of malate dehydrogenase analyses of fish from Lake Isabella.' Twenty samples
analyzed by Dr. D. Phiiipp of the Illinois Natural History Survey.
Frequency of the Florida Allele Based
on Malate Dehydrogenase Analyses
Considering that the incidence of the Florida allele ( M ) was 0.00 in collections
made at Central Valleys Warmwater Hatchery, Shasta Lake, and Merle Collins
Reservoir, values recorded for the study waters indicate that Florida bass had
substantial impact at these waters containing northern bass. Expectedly, there
were differences in the incidence of the Florida allele in the study populations,
based on collections from 1975 through 1978 year classes. The highest values
recorded, 0.65, 0.64, and 0.70, were from New Hogan Reservoir fish of the 1 975,
1976, and 1977 year classes, respectively (Figure 6). Fish from Lake Amador
showed the most uniform values, ranging from 0.33 to 0.39 (Figure 7). Values
for Clear Lake fish showed consistent increases from 0.1 7 in 1 975 to 0.52 in 1 978
(Figure 9). Values ranged from 0.39 in 1976 to 0.44 in 1978 at Folsom Lake
(Figure 5), and from 0.33 in 1976 to 0.51 in 1978 at Lake Isabella (Figure 8).
Sample sizes for 1975 were comparatively small at both waters.
Comparison of the study populations based on these varying values is some-
what speculative considering the many variables related to the complex environ-
ments involved and the following factors that varied by water:
(1) Number of Florida bass planted (Figure 11).
(2) Number of Florida bass planted in relation to the number of northern bass
present.
(3) Size of Florida bass planted (Figure 11).
(4) Surface acreage (Figure 11).
(5) Time of Florida bass plants (Figure 11).
(6) Supplemental stocking of northern bass (Figure 11).
(7) Morphometrv.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES
145
Consideration of values obtained in the final year of the study, however,
provides some measure of the comparative impact of Florida bass. Frequency
of the Florida allele in the study populations based on fish analyzed from the
1978 year class was 0.44 at Folsom Lake, 0.52 at New Hogan Reservoir, 0.35 at
Lake Amador, 0.41 at Lake Isabella (1977 value used because of the compara-
tively small sample size of the 1978 collection), and 0.52 at Clear Lake (Figure
11 ). The Lake Amador value, lowest of the five populations, was significantly
different from that recorded for both New Hogan Reservoir and Clear Lake
(Z = 2.59, p < 0.05), but was comparable to values for Folsom Lake (Z = 1.36,
p >0.05) and Lake Isabella (Z = 0.98, p >0.05). All other values were equiva-
lent when compared (Figure 11).
FREQUENCYOF
FLORIDA ALLELE
LEGEND
S3 MS MM
% FISH BY PATTERN
NO- OF FISH BY PATTERN
1 1
NO. OF FISH ANALYZED
YEARIS) OF COLLECTION- AGE
8ubacript-.no. collected
YEAR CLASS
1969
2 10
1970
1971
4|1|0
9|8|2
5
19
19;5|-3^-
1971^- 4+
1972
1973
0.17 0.27 0.36 0.52
14|7|3
24
I975j- I-
1974
20
W 20 2
70
1975
121111
24
1976
40
20
Ift
•/5|68^8
171
1977
2lW'6
7*
107
T57Fir;
1978
FLORIDA BASS PLANTS
■•■i9W:-\ nrnn
vm\-i i
FIRST SPAWN
;:".:v.d
f:- -1
FIRST SPAWN OF PROGENY
.•.■.•.■■•
^ 1 :::::!
FIGURE 9. Results of malate dehydrogenase analyses of fish from Clear Lake.
0.86 0SS9
FREQUENCYOF
FLORIDA ALLELE
LEGEND
Mo MM
FISH BY PATTERN
NO. OF FISH BY PATTFRN
1
NO. OF FISH ANALYZED
YEAR S) OF COLLECTION -AGE
subscript- no. collected
YEAR CLASS
1971
1972
1 0 2
1975-2+
1976j 3+
1973
0 0 3
1976-2+
1974
29
n
0 14 35
49
1971-0 +
1975-1 +
21
1975
78
22
0 28102
130
1976-0 +
1976
0.85
69
104
1977-0 +
1977
FLORIDA BASS PLANTS
■ ^!^^,
1
FIRST SPAWN
■ .°;'.v''. • •
1
FIRST SPAWN OF PROGENY
.'•'■•"
*■?■'.■
1
FIGURE 10. Results of malate dehydrogenase analyses of fish from Rancho Seco Reservoir.
2—80510
146
CALIFORNIA FISH AND CAME
WATER
Surface
acreage
(maximum
Florida
bass
plants
No. of fish
planted
Size of
fish
planted
Supplemen-
Frequency
95%C.l,for
2 VALUES 1
stocking of
rxjrthern
allele in 1978
llorida allele
1
2
3
4
5
FOLSOM LAKE
(1)
11,450
APR 1972
160
1-5/lb
NO
0.44
034-0 54
1
-
—
—
—
—
APR 1973
262
1-5/lb
MAR«APR
1974
245
1-1-^LB
NEW
HOGAN
RESERVOIR
(2)
4,410
OCT 1971
990
32/lb
NO
0.52
0 42- 062
2
115
—
—
-
-
JULY & OCT
1972
2,967
5/lb
JULY 1973
1y430
^%B
LAKE
AMADOR
(3)
385
MAR i JULY
1970
259
a75^/^^
NO
0.35
026-045
3
136
259
-
-
—
OCT1973
942
«^/lb
LAKE
ISABELLA
11 Ann
JUNE 1972
3,000
~200/lb
NO
0.41^
031- 051
4
048
169
0,98
—
—
(4)
JUNE 1973
24,000
800/lb
APR 1969
136
V,B
YES^
0.52
0.43-063
5
t15
0
2i59
1.70
—
CLEAR LAKE 43,800
MAY 1970
242
Vlb
(5)
OCT 1971
58
Vlb
FIGURE 1 1 . Relationship of surface acreage, Florida bass plants, supplemental stocking, and com-
parison of frequency of Florida allele in collections made at the study waters
in 1978. ' A total of 120,000 fish was stocked by a private group from 1975 through
1978 (L. Week, Fishery Biol., Dept. Fish and Came, pers. commun.) ^ 1977 value used
due to the comparatively small 1978 sample.
According to Dr. David Philipp of the Illinois Natural History Survey (pers.
commun.) evaluation of mixed populations by use of malate dehydrogenase
may lead to overestimates as to the contribution of Florida bass genes to a given
population of northern bass. The actual quantitative measurements of Florida
bass influence at the study waters may be overestimated; however, he is of the
opinion that this is likely a small and relatively constant error. Findings by Dr.
Philipp show that isocitrate dehydrogenase and aspartate aminotransferase now
provide more accurate estimates. These enzyme systems will be required for
future examinations of bass populations at northern California waters since
northern bass from states south of Illinois are now present here. Such fish have
been federally stocked at military installations and Indian reservations in recent
years. The Colorado River, which has had a long and complex history of bass
stocking by adjoining states, likely also contains northern bass from sources
south of Illinois. This is based on electrophoretic and meristic data collected
from fish stocked from the Colorado River area into ponds at the Department's
Imperial Wildlife Management Area in the Imperial Valley of southern California.
Subsequent to the collection of fish from Central Valleys Warmwater Hatchery,
Merle Collins Reservoir, and Shasta Lake, fish from the Imperial Valley ponds
were brought to Central Valleys Warmwater Hatchery. These fish were then
marked and stocked at Merle Collins Reservoir and Coyote Reservoir (Santa
Clara County) . Progeny of Imperial Valley fish that were retained at the hatchery
were stocked at East Park Reservoir (Colusa County) and Salt Springs Reservoir
(Calaveras County). They were likely also included with other bass stocked in
1978 at Shasta Lake, Biscar Reservoir (Shasta County), Mountain Meadows
Reservoir (Lassen County), Lake Almanor (Plumas County), ponds at the Oro-
ville Wildlife Area (Butte County), Clear Lake, Nicasio Reservoir (Marin
County), and various farm ponds.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES
147
Electrophoretic Analysis-Tetrazolium Oxidase
All largemouth bass analyzed for tetrazolium oxidase from Central Valleys
Warmwater Hatchery (100 fish), Shasta Lake (68 fish), and Merle Collins Reser-
voir (42 fish) showed the MM phenotype (Figure 12) as expected for northern
bass. Of 68 fish analyzed from Upper Otay Reservoir, 43 (63.2%) showed the
MM phenotype, 22 (32.4%) were MS, and 3 (4.4%) were SS. Of 83 fish
analyzed from Hidden Valley Reservoir, 44 (53.0%) were MM, 36 (43.4%)
were MS, and 3 (3.6%) were SS.
WATER
YEAR
CLASS
NUMBER OF FISH
BY PHENOTYPE
NUMBER
OF FISH
ANALYZED
MM
MS
SS
NORTHERN
BASS
POPULATIONS
CENTRAL VALLEYS
WARMWATER HATCHERY
100
0
0
100
SHASTA LAKE
68
0
0
68
MERLE COLLINS RESERVOIR
42
0
0
42
FLORIDA
BASS
POPULATIONS
UPPER OTAY RESERVOIR
43
22
3
68
HIDDEN VALLEY RESERVOIR
44
36
3
83
STUDY
POPULATIONS
FOLSOM RESERVOIR
1974
21
4
0
25
1976
58
2
0
60
NEW HOGAN RESERVOIR
1976
103
14
1
118
LAKE AMADOR
LAITE ISABELLA
1975
34
4
1
39
1976
23
1
1
25
CLEAR LAKE
1973
16
3
0
19
1974
19
3
0
22
STUDY POPULATIONS COMBINED
274
31
3
308
FIGURE 12. Results of tetrazolium oxidase analyses offish from northern bass populations, Florida
bass populations, and study populations.
Predictably, MM was the most frequently found phenotype in fish analyzed
from the study populations. Of 308 fish examined, 274 (89.0%) were MM, 31
(10.0%) were MS, and 3 (1.0%) were SS. Results for fish from Rancho Seco
Reservoir were comparable to those for fish from Upper Otay and Hidden
Valley reservoirs. Of 143 analyses, 81 (56.6%) were MM, 56 (39.2%) were MS,
and 6 (4.2%) were SS.
148 CALIFORNIA FISH AND CAME
Known Fi hybrids by MDH were not analyzed for TO; however, of the 128
MS fish (MDH) from the study waters that were analyzed for TO, 109 were MM
and 19 were MS.
Considering that northern or Florida bass or their subspecific hybrids can
show the MM phenotype for tetrazolium oxidase (northern bass always MM,
Florida bass may be MM, MS, or SS, and subspecific hybrids may be MM or
MS), use of TO for classifying individual fish has limited value. This system is
useful, however, for determining if Florida bass or subspecific hybrids are
present in a population thought to contain northern bass only. In this regard, the
presence of the MS or SS phenotype would indicate contamination. One would
reasonably expect to find an MS phenotype (SS being in very low incidence
even in Florida bass populations) in the collections from Central Valleys Warm-
water FHatchery, Shasta Lake, or Merle Collins Reservoir if Florida bass or sub-
specific hybrids were present. For example, combining TO analyses for Upper
Otay (68 fish) and FHidden Valley reservoirs (83 fish) showed that 58 fish, or
about one out of every three fish, had the MS phenotype. Combining the TO
analyses for fish from the study waters (308 fish) showed that 31 fish, or about
one out of every 1 0 fish, had the MS phenotype ( Figure 12). Therefore, it would
not be unreasonable to expect to find at least one MS fish in the collections from
Central Valleys Warmwater Hatchery, Shasta Lake, and Merle Collins Reservoir,
considering the number of fish examined from each source.
Meristic Analysis
Results from discriminant function analysis of meristic data for fish of known
MDH phenotypes showed that meristic values were not reliable for classifying
individual fish from mixed populations as to Florida (MM), northern (SS), or
hybrid bass (MS) categories. When meristic data for 69 MM fish from Upper
Otay Reservoir, 271 MS fish from mixed populations, and a total of 167 SS fish
from Central Valleys Warmwater Hatchery and Merle Collins Reservoir were
analyzed as a whole, a considerable number of fish were categorized incorrect-
ly. Only 32 Upper Otay fish were placed in the MM category, while 35 were
classified as MS and two were classified as SS (Figure 13). Similar results were
obtained when a total of 370 MM fish from Upper Otay and mixed populations,
271 MS fish from mixed populations, and a total of 427 SS fish from Central
Valleys, Merle Collins, and mixed populations were considered as a whole. Of
370 MM fish, 261 were classified MM, 83 MS, and 26 SS. Of 271 MS fish, 115
were classified MS, 91 MM, and 65 SS. Of 427 SS fish, 369 were classified SS,
57 MS, and one MM. When 69 MM fish (Upper Otay) and 167 SS fish (Central
Valleys and Merle Collins) were analyzed together, five of the former were
categorized SS and four of the latter were classified MM.
Analysis also showed that the lateral line scale count was the most discriminat-
ing meristic character. Based on calculated values of the F-statistic, a measure
of significant difference between groups for the character, the lateral line scale
count was the most significantly different character (F = 563.0770), followed
by pyloric caeca (50.3735), scale rows around the caudal peduncle (21.2659),
scale rows above the lateral line (4.3975), scale rows on the cheek (3.4029),
and scale rows below the lateral line (2.2009) . For this reason, data are provided
for lateral line scale counts only.
FLORIDA LARGEMOUTH BASS ELECTROPHORETIC STUDIES 149
CLASSIFIED BY
.ELECTROPHORESIS M ERISTICS^
» /69mm upper otay reservoir
507 FISH ^271ms mixed populations
MS SS TOTAL
32 35 2 69
52 183 36 271
\yHg7 CEm-RAL VALLEYS W/W HATCHERY* ► 1 20 146 167
MERLE COLLINS RESERVOIR
D •STOmm "PPER otay RESERVOIR 4 ► 261 83 26 370
° / MIXED POPULATIONS ^
1,068 FISH ^^ ^271mS mixed POPULATIONS * 9' ''^ 65 2/1
427qq CENTRAL valleys VI//W/ hatchery, »• 1 57 369 427
MERLE COLLINS RESERVOIR &
MIXED POPULATIONS
C ^69mm upper OTAY RESERVOIR '- ► 64 5 69
'MM
236 FISH
SS
Nl67ec CENTRAL VALLEYS W/// HATCHERY 4 * 4 163 167
MERLE COLLINS RESERVOIR
FIGURE 13. Results of discriminant function analysis-classification by meristic values of fish of
known malate dehydrogenase phenotypes. The six meristic values used included
number of 1 ) scales along lateral line, 2 and 3) scale rows above and below lateral
line, 4) scale rows around caudal peduncle, 5) scale rows on cheek, and 6) pyloric
caeca. A = 507 fish considered as a whole (MM and SSfish from Florida and northern
populations only). B = 1068fish considered as a whole (MM and SS fish from Florida,
northern, and mixed populations). C = 236 fish considered as a whole (classification
of MM and SS fish only).
Northern largemouth bass lateral line scale counts ranged from 59 to 68
(x = 63.3, n = 100) for Central Valleys Warmwater Hatchery fish, from 59 to
69 (x = 64.0, n = 129) for Merle Collins Reservoir fish, and from 60 to
69 (x = 65.0, n = 73 ) for fish from Shasta Lake. Florida bass counts ranged from
66 to 75 (x = 70.5, n = 81 ) for Upper Otay Reservoir fish, and from 64 to 76
(x = 70.2, n = 93) for fish from Hidden Valley Reservoir.
Lateral line scale counts for all largemouth bass collected from the study
waters following the introduction of Florida bass ranged from 53 to 79
(x = 66.2, n = 1,386). Counts made by Bottroff (1967) on largemouth bass
from Folsom Lake prior to the 1972 introduction of Florida bass ranged from 56
to 69 (x = 63.4, n = 223). Post-introduction counts ranged from 53 to 78
(x = 65.6, n = 559) for fish collected from 1974 through 1977 (Figure 14).
Florida bass were introduced at New' Hogan Reservoir in 1971. Counts made
prior to that ranged from 57 to 68 (x = 63.4, n = 76). Post-introduction values
for fish from 1975, 1976, and 1977 year classes ranged from 59 to 79 (x == 68.5,
n = 278) (Figure 14).
No pre-Florida bass data were available for Lake Amador or Lake Isabella;
however, post-introduction values ranged from 61 to 73 (x = 66.1, n = 155)
and from 59 to 75 (x = 67.2, n = 114), respectively (Figure 14).
Pre-Florida bass introduction counts ranged from 58 to 68 (x = 63.7,
n = 140) for Clear Lake fish (J. Broadway, M. Fairbank, and S. Morse, Univ. of
California, Davis, unpublished data). Post-introduction values (1973 and 1975)
ranged from 58 to 74 (x = 64.7, n = 280) (Figure 14).
150
CALIFORNIA FISH AND CAME
<
<
d
^0
i§
98
^^
Q-
£ X
CO CO
Z O
UJ
"r a
0 0
0
-S
z
z g
LU
D 0
0
0 TT
UJ
U 0
^^^^
CO
<
X
>-
3
E
o
c
o
re
01
c
n3
O)
c
o
3
>-
u
c
0)
D
U
FLORIDA LARGEMOUTH BASS ELECTROPHORETIC STUDIES 151
Counts for known F, hybrids ranged from 58 to 72 (x = 65.7, n = 53), ex-
cluding abnormally low counts of 46, 47, and 52 ( Figure 4) . Values for fish from
the study waters showing the MDFH hybrid pattern ranged from 59 to 77
(x = 66.9, n = 313).
Scale counts for Rancho Seco Reservoir fish (1975 and 1976) ranged from 62
to 82 (x = 72.8, n = 284).
Use of Meristic Data in Evaluating Study Populations
Electrophoretic data were collected because meristic data appeared to be of
limited value in meeting the objectives of this study:
(1) Categorization of individual fish from mixed populations would be dif-
ficult because of overlaps in ranges of meristic values for the subspecies
and their hybrids.
(2) FHybridization could probably not be demonstrated by increases over
time in mean meristic values for study populations since such increases
would likely occur with no hybridization because of higher survival by
longer-lived, less vulnerable Florida bass.
(3) Hybridization could not necessarily be demonstrated by a frequency
distribution of meristic values for fish sampled from a mixed population
because of its possible similarity to a distribution postulated for a compa-
rable population of the two subspecies spawning independently and with
differing annual mortality rates.
(4) While changes in meristic values may have provided indications that
hybridization had occurred (extended ranges and/or unimodal distribu-
tion of values, etc.), determination of the extent of hybridization was
unlikely.
Bailey and Hubbs (1949) reported a range of lateral line scale counts of 59
to 69 for northern bass from the Great Lakes and the Mississippi River, a range
of 65 to 75 for Florida bass from the Florida Peninsula, and an overall range of
58 to 76 for apparent hybrids from various Florida and Georgia waters. Lateral
line scale counts for fish identified electrophoretically by this study as northern
bass ranged from 59 to 69. Counts for Florida bass ranged from 64 to 76. Counts
for fish from mixed populations ranged from 53 to 78, and those for known F^
hybrids ranged from 58 to 72. It is apparent from these overlapping ranges that
one cannot expect to classify individual fish from mixed populations as to
subspecific or hybrid categories with reasonable accuracy on the basis of a
lateral line scale count. Similar overlaps occurred for other scale counts and for
pyloric caeca counts.
Mean lateral line scale counts for northern bass populations reported by Bailey
and Hubbs (1949) ranged from 62.6 to 64.6. Bottroff (1967) reported mean
counts of 61 .2 to 63.9 for several California populations. Lateral line scale counts
for Central Valleys Warmwater Hatchery fish averaged 63.3, and those for fish
from Merle Collins Reservoir averaged 64.0. Fish from Shasta Lake averaged
65.0. While this mean was abnormally high for a northern bass population, no
individual count exceeded the range typically reported for northern bass. The
mean lateral line count for fish collected prior to introduction of Florida bass was
63.4 at Folsom Lake and at New Hogan Reservoir, and 63.7 at Clear Lake. Mean
counts for fish collected at the study waters following the introduction of Florida
bass ranged from 64.5 to 66.8 at Folsom Lake, 66.5 to 70.3 at New Hogan
Reservoir, and 65.8 to 66.6 at Lake Amador. Post-introduction values were 67.7
152 CALIFORNIA FISH AND GAME
and 66.9 at Lake Isabella and 64.4 and 65.2 at Clear Lake. This would suggest
that hybridization could be detected by an increase in mean lateral line count
to a value of 65 or more. Such an increase, however, would likely have occurred
at the study waters with no intersubspecific spawning, considering the differing
annual mortality rates of 0.55 for northern bass and 0.25 for Florida bass reported
by Bottroff and Lembeck (1978). Considering that Florida bass were stocked
into established populations of northern bass at the study waters at a ratio of at
least one Florida bass for every 50 northern bass, an increase in the mean lateral
line scale count to 65 scales for fish representatively collected from the study
populations would likely not have occurred for several years. However, if young
Florida bass survived at a disproportionate rate that time would have been
substantially reduced.
One might expect the frequency distribution of lateral line scale counts for fish
from an intergraded population to show a unimodal distribution (Figure 15D).
Conversely, the frequency distribution of a population of Florida and northern
bass spawning independently and with differing mortality rates should eventual-
ly show a bimodal distribution. Bimodality would most likely occur at 67, 68, or
69 scales, which are at the upper end of the northern range and near the lower
end of the Florida range (combining A and B of Figure 15). Bimodality would
be most apparent in populations having equal numbers of the two subspecies.
At the study waters, however, Florida bass were initially outnumbered by north-
ern bass by a wide margin. For this reason, bimodality would likely not be
detected in representative samples for several years (Figure 16).
Figure 16 provides frequency distributions of lateral line scale counts that one
might expect to find if a yearling population of 15,950 northern bass and 319
Florida bass, a 50 to 1 ratio (a conservative estimate of the initial ratio at the
study waters), was examined each year over a 5-year period when: 1 ) the two
subspecies were dying at the differing rates (0.55 for northern bass and 0.25 for
Florida bass) reported by Bottroff and Lembeck (1978); 2) within the respective
groups, no scale count was being removed disproportionately; and 3) all fish
were marked for separation. Northern bass scale counts were expanded propor-
tionally from the 302 counts recorded for fish from Central Valleys Warmwater
Hatchery, Shasta Lake, and Merle Collins Reservoir. Counts for fish from Upper
Otay and Hidden Valley reservoirs were used for Florida bass. In this hypotheti-
cal exercise in which there was no intersubspecific spawning and recruited fish
were not considered, bimodality began to appear among the surviving fish at 69
scales in the fourth year.
Given the same initial population, the frequency distributions of Figure 16
likely also approximate the scale counts of fish representatively sampled from
that population (including recruited fish) each year over a 5-year period when:
1 ) no intersubspecific spawning occurred; 2) the two subspecies were dying at
the differing rates reported by Bottroff and Lembeck (1978); 3) survival to
sampling of young fish of each subspecies was comparable; and 4) the incidence
of each lateral line scale count for fish recruited into the population was propor-
tional to the incidence of that count in the initial population. Under these
conditions, bimodality could conceivably be detected as early as the fourth year.
If, however, fish with lateral line scale counts of 67, 68, or 69 were recruited into
a population at a disproportionate rate, bimodality may not be detected and the
frequency distributions for sampled fish would likely show a unimodal distribu-
FLORIDA LARGEMOUTH BASS ELECTROPHORETIC STUDIES
153
I = COUNTS OF 64
OR MORE
X = 70.3
mod« = 70
n = 319-1-
58 60 62
64 66 68 70 72 74 7$ 78
LATERAL LINE SCALES
END OF 1st YEAR
END OF 3n) YEAR
END OF 5th YEAR
5860626466687072 74 76
LATERAL LINE SCALES -
FIGURE 15. Frequency distributions of lateral line scale counts for: (A) northern bass from Central
Valleys Warmwater Hatchery, Shasta Lake, and Merle Collins Reservoir combined;
(B) Florida bass from Upper Otay and Hidden Valley reservoirs combined; (C)
known F, hybrids; and (D) A + B + C (53 counts expanded to 300 on a proportional
basis). ' Includes 145 counts made by L. Bottroff (unpubl. data).
FIGURE 16. Frequency distributions of lateral line scale counts for an initial population composed
of 1 5,950 northern bass and 319 Florida bass ( a 50 to 1 ratio ) , and applying the annual
mortality rates of 0.55 for northern bass and 0.25 for Florida bass reported by Bottroff
and Lembeck (1978) over a 5-year period. Northern bass counts were expanded
proportionally from the 302 counts recorded for fish from Central Valleys Warmwater
Hatchery, Shasta Lake, and Merle Collins Reservoir. Counts for fish from Upper Otay
and Hidden Valley reservoirs were used for Florida bass.
154 CALIFORNIA FISH AND CAME
tion. Inadequate sample size or sampling error may also give frequency distribu-
tions falsely suggestive of an intergraded population.
Various changes in lateral line scale count values following the introduction
of Florida bass into a northern bass population such as 1 ) an increase in mean
count, 2) the occurrence of individual values that exceed the combined ranges
of the two subspecies, and 3) the unimodality of a frequency distribution of
values may suggest that intersubspecific spawning has occurred. These indica-
tors do not provide, however, a measure of the extent of hybridization or an
insight into the makeup of the resultant population.
Compilation of meristic, as well as electrophoretic data for study populations,
for populations of Florida and northern bass, and for known Fi hybrids provided
an opportunity to assess the value of meristics for detecting hybridization. In this
regard, the mode value of lateral line scale counts for fish of a mixed population
where a comparatively few Florida bass were stocked, appeared to provide
greater insight than other indicators. The mode value of a distribution of lateral
line scale counts is typically 63 or 64 for a northern bass population (Bottroff
1967 and Figure 15A), and 70 for a Florida bass population (Bottroff 1967 and
Figure 15B). Mixed populations typically exhibit a mode ranging from 65 to 70
(Bottroff 1967). Consistent with this, a hypothetical population composed of
equal numbers of northern bass, Florida bass, and known Fi hybrids had a mode
of 66 (Figure 15D). While distributions for fish from the study waters were
generally multimodal because of comparatively small sample sizes (Figure 14)
it is apparent that the mode for larger samples from these waters would fall
within the aforementioned range. For example, combining collections from
Folsom Lake (n = 559) gives a mode of 65. Combining collections from New
Hogan Reservoir (n = 278) gives a mode of 69. Also, a comparison of the
percentage of fish with counts of 64 or greater in a northern bass distribution
(darkened portion of Figure 15A) with the percentage of fish with those counts
in the hypothetical mixed population (darkened portion of Figure 15D) and in
the study populations (darkened portions of Figure 14 post-Florida bass) indi-
cates that the mode value for most study water collections lies between 65 and
70. The percentage of values 64 or greater in a northern population distribution
is usually about equal to or less than the percentage of values less than 64
( Bottroff 1 967 and Figure 1 5A ) . Contrastingly, the percentage of fish with values
of 64 or greater in distributions of the hypothetical mixed population and actual
collections made at the study waters exceeds the percentage of fish with values
less than 64. Bottroff's (1967) distributions were equivalent in this respect.
Population Sampling
Two major factors related to sampling could have affected the evaluations:
(1 ) A correlation between isozyme pattern and susceptibility to electrofish-
ing.
( 2 ) Differences in the makeup of collections between years being a reflection
of sampling error rather than changes within the populations.
Most fishery workers involved with comparative tests report that Florida bass
are considerably more wary than northern bass (Zolczynski and Davies 1976;
Rieger, Summerfelt, and Gebhart 1978). For this reason, one would expect
Florida bass to be more difficult to capture by electrofishing. Consistent with the
findings of Zolczynski and Davies (1976) that Florida bass ceased feeding and
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES 155
moved into deeper water in response to fishing, Florida bass should move from
shallow water into deeper water in reaction to an approaching electrofishing
boat with its associated bright lights and noisy generator (or alternator) . I found,
however, that adult Florida bass were no more difficult to capture at Hidden
Valley Reservoir and Rancho Seco Reservoir (mostly Florida bass present), than
northern bass were at Merle Collins Reservoir and other waters. If Florida and
northern bass differ in susceptibility to electroshocking the age group least likely
to demonstrate this would probably be young-of-the-year fish. Most fish collect-
ed at the study waters were young-of-the-year. While these fish ranged consider-
ably as to size, no correlation was found between a given MDH pattern and size.
Considering the incidence of the three MDH patterns in collections from the
study waters, over time and when comparing one water with another, I do not
believe that MM, MS, or SS fish showed appreciably different susceptibilities to
the electrofishing gear.
It is possible that sampling error was responsible for some differences in the
makeup of collections between year classes. There are indications, however,
that through rigid adherence to collection guidelines previously listed, these
differences were mostly a reflection of actual changes in the population makeup
rather than changes falsely represented through sampling error. For example, the
incidence of fish showing the three MDH isozyme patterns in collections from
Lake Amador remained relatively constant from 1975 through 1978 (Figure 7).
Appreciable sampling error would have caused noticeable differences between
two or more of these years.
Rancho Seco Reservoir
A small pond at the eventual site of Rancho Seco Reservoir was chemically
treated to eradicate all fish life prior to inundation of the reservoir basin. It is
likely that this treatment was successful and that northern bass were not present
when Florida bass were introduced in 1971. The presence of one fish of the
northern bass MDH phenotype among fish analyzed from the 1973 year class,
however, showed that the Rancho Seco Reservoir population included northern
bass alleles. It is possible that a small number of northern bass were inadvertently
pumped into the reservoir from the nearby Folsom South Canal or were trans-
planted by anglers from another source.
While no SS (northern bass) phenotypes were found in collections from the
1975, 1976, and 1977 year classes, MS (hybrid) phenotypes were represented
( Figure 10). It is probable that the Rancho Seco Reservoir population contained
hybrid fish at the time it was utilized as a source for some of the study waters
(Figure 1 ). The incidence of hybrid fish in groups stocked from the reservoir
from 1 971 through 1 974 was likely low, however, considering that comparatively
few northern bass were initially involved. An indication that Rancho Seco Reser-
voir contained few hybrids in the early years comes from a comparison of the
frequency of the Florida allele in 1978 at New Hogan Reservoir (0.52) and Clear
Lake (0.52). New Hogan Reservoir was the only study water that received fish
from Rancho Seco Reservoir only. Clear Lake was planted from Upper Otay and
Hidden Valley reservoirs. Also, it is unlikely that the high incidence of the Florida
allele at New Hogan Reservoir in 1975 (0.65), 1976 (0.64), and 1977 (0.70)
would have occurred if an appreciable number of hybrids were present in plants
made there from Rancho Seco Reservoir.
1 56 CALIFORNIA FISH AND GAME
Maladaptive Genes
Apparent intolerance of 4° C by Florida bass reported by Johnson (1975)
prompted concern that maladaptive genes possibly related to this intolerance
would be transmitted to northern bass populations through Florida bass intro-
duction. Quoting from Johnson:
"Low temperature stress was suspected as the cause of poor survivorship of
Florida bass in the Ashland ponds and Phillips Lake. As a preliminary test,
three Florida and three northern bass were subjected to rapid temperature
decreases (acclimated to 2rc for 48 hours and then exposed to a reduction
in temperature from 21° to 4° within 12 hours). Florida bass mortality was
100% in the two replicates over a 7-day test period. Only one of the six
northern largemouth bass died. Although the experimental design was limited,
the results point to a greater sensitivity for Florida largemouth bass than for
the northern subspecies. A subsequent investigation of this question utilized
a large outside tank which held 20 Florida and 20 northern largemouth. The
fish were acclimated at 15°C (59°F) and then subjected to gradually decreas-
ing temperatures. Mortality was similar in the two subspecies until the ninth
day at a temperature of 5°C (4rF). The temperature was held at 4°C (39°F)
for 5 days. Fourteen days after the inception of the experiment, all Florida bass
were dead while only three northern bass had died. While these data do not
prove winter mortality in ponds is caused by low temperature, it does indicate
a difference in temperature tolerance between the two subspecies. The Florida
bass is much more sensitive to a rapid decline in temperature."
Results of these tests suggest that Florida bass are more sensitive to a rapid
decline in temperature than are northern bass. These tests should have included,
however, control fish of both subspecies held in comparable tanks at optimal
temperature. My experience with Florida bass has been that they initially are
more wary and, as a result, more stressed by handling than are northern bass.
For this reason, one might expect that Florida bass, disproportionately stressed
before entering comparative, stressful tests with northern bass, would show a
higher mortality. Colby ( 1 973 ) cautioned against extrapolating laboratory results
to explain natural events. He cited laboratory tests of temperature tolerance of
alewives, Alosa pseudoharengus, and endemic species that showed differential
mortalities of alewives at temperatures <3°C, suggesting that they were likely
vulnerable to the low temperatures which occur in the Great Lakes. The fact that
alewives were captured in trawls in the Great Lakes in waters colder than 2°C
suggested that captivity may reduce low temperature tolerance.
Several points should be considered in relating Johnson's findings to Florida
bass in northern California waters:
( 1 ) It is unlikely that temperature declines at rates comparable to those used
by Johnson would occur at California's low- and mid-elevation reser-
voirs.
(2) Florida bass survived outdoor temperatures (including freezing condi-
tions in which only aeration of the holding tanks prevented them from
freezing over) for two winters (1977-78, 10 fish; 1978-79, 13 fish) at the
Department's Field Station.
(3) No mortalities occurred among 61 F, hybrids held in outdoor tanks at the
Field Station during winter 1978-79.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES 157
(4) Considering the obvious genetic impact of the comparatively few Florida
bass stocked at the study v^aters, it is unlikely that they or their progeny
suffered appreciable wintertime mortalities.
(5) No unusual wintertime dieoffs of bass at the study waters were reported
by fishery workers, marina operators, or anglers.
Results of this study indicate that considerable variation exists among fish of
the intergraded populations. Of particular interest here are variant forms of
enzymes related to temperature compensation. The enzyme reactions which
exhibit the highest degree of temperature compensation are primarily those
involved in generating the energy "currency" (ATP, NADH, etc. ) needed by the
cells at all times (Hochachka and Somero 1973). Malate dehydrogenase is such
an enzyme. According to Hochachka and Somero (1971) for an organism
experiencing changes in habitat temperature over daily or hourly time spans, it
would seem advantageous to have two or more variants of a given enzyme in
its tissues which, by acting together, could promote thermally independent
enzyme function over a wider range of temperatures than would be possible if
only a single form of the enzyme were present.
Performance Capabilities of Fish of Intergraded Populations
Malate dehydrogenase isozyme patterns used to identify northern and Florida
bass, for which some performance capabilities have been described, have lim-
ited use in predicting the performance of individual fish of intergraded popula-
tions. A fish showing a Florida bass enzyme pattern, for example, may or may
not spawn earlier, grow faster, live longer, or demonstrate other attributes as-
signed to Florida bass. The performance capability of a fish is ultimately deter-
mined by its biochemical makeup (Hochachka and Somero 1973). While MDH,
an enzyme involved in energy transfer, is a part of that makeup, isozyme patterns
of MDH do not necessarily indicate the behavioral, anatomical, or physiological
characteristics of fish. Results of this study showed, however, that the heterozy-
gote of Florida bass x northern bass possesses MDH isozymes of both parents
plus an additional isozyme found in neither parent. Similarly, Dr. Philipp (pers.
commun.) identified heterozygous patterns for two additional enzymes, iso-
citrate dehydrogenase and aspartate aminotransferase, in Lake Isabella fish of the
1978 year class. Several workers have reported variant isozymes for several
enzymes in hybrids resulting from inter- and intraspecific crosses (Goldberg
1966; Aspinwall and Tsuyuki 1968; Bailey and Wilson 1970; Whitt, Childers, and
Wheat 1971; Metcalf, Whitt, and Childers 1972; Wheat, Whitt, and Childers
1973; Whitt, Childers, and Cho 1973; Whitt et al. 1973; Avise and Smith 1974).
Umbarger (1961 ) proposed that additional isozymes provide auxiliary routes
for energy transfer. According to Ayala (1978) the manufacture of slightly
variant proteins by the heterozygote may enable it to adapt to a broader range
of conditions and individuals that are heterozygous at a number of loci are
usually stronger and reproductively more successful than individuals homozy-
gous at a large number of loci. Several workers have reported that progeny from
crosses between species or inbred lines show increased vigor termed heterosis
(Hubbs and Hubbs 1930; Shull 1948; Whitt et al. 1973; Wheat, Childers, and
Whitt 1974; Ayala 1978). Utter, Hodgins, and Allendorf (1974) pointed out that
studies of interspecific variation can be extended through studies of species
hybrids because of the greater amount of genetic variation that exists between
158 CALIFORNIA FISH AND CAME
any two species than that which exists within either of them. Ayala ( 1 978) stated
that a population that has considerable variation may be hedged against future
changes in the environment.
Results of this study indicate variability of characteristics among fish of the
intergraded populations in two major ways. Firstly, the range of meristic values
for fish sampled from the mixed populations typically equalled, and in some
cases overlapped, the combined ranges for the subspecies involved. Fish of
given MDhH isozyme patterns had quite variable meristic values, particularly
those collected in the latter years of the study. For example, some fish showing
the northern bass pattern had counts as high as 75, while some fish showing the
Florida bass pattern had counts as low as 62. Meristic values for MS fish typically
showed the greatest variability. Lateral line scale counts of MS fish collected in
1 976 from Folsom Lake ranged from 60 to 76. Similarly, MS fish from New FHogan
Reservoir in 1976 had counts ranging from 60 to 78. It is, therefore, reasonable
to assume that if variability exists between isozyme pattern and meristic values
this variability could extend to other characteristics.
Secondly, since fish of the study populations exhibited one of three MDH
isozyme patterns, and some fish from Lake Isabella demonstrated heterozygous
patterns for two other enzymes, it is likely that fish of the intergraded populations
exhibit variant forms of other enzymes. The possible combinations resulting from
this are considerable.
It is reasonable to assume that the current largemouth bass populations at the
study waters possess a wider spectrum of performance capabilities than that
previously present. This is consistent with the original intent of introducing
Florida bass which were reported to grow faster, live longer, spawn earlier, and
be more difficult to catch than northern bass. Inclusion of these and other traits
likely yielded populations composed of individuals ranging from those showing
mostly Florida bass traits to those showing mostly northern bass traits. This
variability would be particularly advantageous in the reservoir setting where
heavy angling pressure, water level manipulation, competition of prey species
with small bass, and other factors work against the maintenance of a bass
population.
Management Implications
Indications of the management implications of Florida bass introduction come
from Bottroff and Lembeck (1978) in relating their findings at San Diego County
reservoirs where Florida bass were introduced into established populations of
northern bass:
. . . populations with Florida-like characteristics are resistant to overharvest by
anglers. The mean size of bass caught and the incidence of trophy specimens
has increased in reservoirs where Florida bass have been established. In-
creased bass yields were associated largely with the development of hybri-
dized populations although one impoundment containing bass with
Florida-like characteristics provides angling of exceptional quality.
Pre- and post-Florida bass introduction census data were not available for the
study waters. There are indications, however, that Florida bass had a positive
impact at some of these waters. According to R. Lockhart, Sr. (Operator, Lake
Amador Resort, pers. commun.) bass fishing has been excellent at Lake Amador
in recent years. In spring 1978 anglers caught over 100 largemouth bass weighing
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES 159
between 3.2 kg and 5.9 kg. During the first 9 months of 1979, anglers caught over
100 bass weighing between 3.2 kg and 4.9 kg. Lockhart pointed out that his
records include only the catches of anglers who voluntarily stop at the resort
headquarters prior to departing.
B. Burke ( Marina Owner, New Hogan Reservoir, pers. commun. ) reports that
largemouth bass fishing has been good at the reservoir in recent years. Highlight-
ing catches made during the first 9 months of 1 979 were four bass, each weighing
over 4.5 kg.
In 1976 L. Week (Fishery Biologist, Calif. Dept. Fish and Game, pers. com-
mun.) verified the weight of a 4.6 kg largemouth bass, establishing a new record
weight for bass at Clear Lake. According to Week, bass fishing has improved
considerably at the lake since early 1978, after more than a decade of poor
fishing. He does not relate this to the heavy supplemental stocking of northern
bass conducted at the lake for several years by a private group. Electrofishing
surveys directed at assessing the survival of these fish, mostly fingerlings, have
yielded very low returns. For example, the marked fingerlings (110,000) stocked
in July 1979 made up only 3.8% of young-of-the-year bass collected one month
later. Week also reports that largemouth bass reproduction has increased con-
siderably. Electrofishing surveys in August 1978 and 1979 yielded 123 and 243
young-of-the-year per kilometre, respectively.
Loss of habitat in the form of underwater trees and brush is thought to be
responsible for the decline in largemouth bass catches at Folsom Lake, which
began in the early 1960's. Since then, smallmouth bass, M. dolomieui, have
dominated bass catches (Pelzman, Rapp, and Rawstron 1980). No information
was obtained that would indicate that this trend was reversed by the introduc-
tion of Florida bass. In 1965 largemouth bass constituted only about 3% of the
sport catch at Lake Isabella (Hayden 1966). No information was obtained that
would suggest that Florida bass substantially improved this situation. While in the
long term, the introduction of Florida bass may increase bass catches at Folsom
Lake and Lake Isabella, it is perhaps unrealistic to expect Florida bass to marked-
ly improve bass fishing at waters where conditions are such that established
northern bass populations are providing only marginal fishing.
Results of this study and of the study at San Diego County reservoirs ( Bottroff
and Lembeck 1978) showed that:
(1 ) There is considerable overlap in the spawning periods of northern and
Florida bass, and intersubspecific spawning will likely occur when the
two are present in the same water.
(2) Introduction of Florida bass provides a method for reducing the high
harvest rates typically recorded for northern bass populations in Califor-
nia.
(3) Anglers may catch fewer bass following the introduction of Florida bass;
however, the mean size of bass in the catch is greater.
(4) The incidence of trophy-sized bass increased at most waters where Flori-
da bass were introduced.
For these reasons, consideration should be given to stocking Florida bass into
northern bass populations at additional, selected northern California waters.
Also, intergraded populations should serve as a source for stocking at newly
created reservoirs and for restocking dewatered reservoirs.
160 CALIFORNIA FISH AND GAME
ACKNOWLEDGMENTS
Robert R. Rawstron was instrumental in getting this study underway and
provided helpful advice during its term. William F. Childers of the Illinois Natural
History Survey provided information necessary to carry out the electrophoretic
analyses. His willingness to provide guidance, particularly in the early stages of
the study, is most appreciated. Robert V. Pollard of the Biostatistical Unit,
Department Planning Branch, carried out the discriminant function analyses, and
prepared the brief description of the method. Stephen A. Rapp contributed
considerably toward completion of the study through his attention to detail and
enthusiasm toward all phases of the work. David B. Hohler, Lucy G. Williams,
and Bruce G. Trotter made valuable contributions to the project through their
attention to accuracy in handling the often tedious meristic work and in carrying
out other assignments. Julie M. Cullen prepared the figures and helped organize
the data into their final form. Michael H. Fairbank, Mary E. Bacon, David P.
Drake, William C. Robinson, Susan L. Vandermeer, Prudence Silger, Dennis D.
Waterhouse, Robert W. Sneddon, Vida B. Wong, Wayne K. Hubbard, Dale K.
Hoffman, Paul F. Ogasawara, and Katharine Shotwell also made significant
contributions. The intersubspecific spawning of Florida and northern bass at the
Field Station was accomplished largely through the help of Michael D. Cochran
and Donald F. Estey, who shared their considerable knowledge of bass culture.
Cochran also provided northern bass from Central Valleys Warmwater Hatch-
ery. Lawrence J. Bottroff collected fish from Upper Otay Reservoir and provided
information on the history of Florida bass plants. William F. Van Woert provided
fish from Shasta Lake. Larry E. Week and Charles W. Marshall made the 1978
year class collections from Clear Lake and Lake Isabella, respectively. Janice M.
Rhinehart typed the manuscript draft. The manuscript was reviewed by Charles
E. von Geldern, Jr., David P. Philipp, Robert V. Pollard, Earle W. Cummings,
David A. Jessup, Kenneth F. Levine, and M. Ralph Carpenter. Charlene B. Gage
typed the final copy.
REFERENCES
Addison, ). H., and S. L. Spencer. 1971. Preliminary evaluation of three strains of largemouth bass, Micropterus
salmoides (Lacepede), stocked in ponds in south Alabama. Proc. 25th An. Conf. Southeast, Assoc. Came Fish
Comm. pp. 366-374.
Afifi, A. A., and S. P. Azen. 1972. Statistical analysis — a computer oriented approach. Academic Press. New York
and London. 366 p.
Aspinwall, N., and H. Tsuyuki. 1968. Inheritance of muscle proteins in hybrids between the redside shiner
Richardsonius balteatus and the peamouth chub Mylocheilus caurinum. Can., Fish, Res. Bd., J., 25 (7) :1 317-
1322.
Avise, J. C, and M. hi. Smith. 1974. Biochemical genetics of sunfish. II. Genetic similarity between hybridizing
species. The American Naturalist, 108 (962):458-472.
Ayala, F. A. 1978. The mechanism of evolution. Scientific American, 239(16):56-69. S. 1978.
Bailey, G. S., and A. C. Wilson, 1970. Multiple forms of supernatant malate dehydrogenase in salmonid fishes. J.
of Biol. Chem., 245(22):5927-5940.
Bailey, R. M., andC. L. Hubbs. 1949. The black basses (Micropterus) of Florida with a description of a new species.
Univ. Mich., Mus. of ZooL, Occas. Papers, 516:40 p.
FLORIDA LARCEMOUTH BASS ELECTROPHORETIC STUDIES 161
Bottroff, L. ). 1967. Intergradation of Florida bass in San Diego County. M. S. Thesis. San Diego State College, San
Diego, California. 131 p.
Bottroff, L. )., and M. E. Lembeck. 1978. Fishery trends in reservoirs of San Diego County, California, following
the introduction of Florida largemouth bass, Micropterus salmoides floridanus. Calif. Fish Game, 64 ( 1 ) : 4-23.
Bryan, C. F. 1964. Growth and systematic relationships of Micropterus punctulatus (Rafinesque) using merlstic
traits and serum electrophoresis. Ph.D. Thesis, Univ. Louisville, Kentucky. 184 p.
1969. Variation in selected meristic characters of some basses, Micropterus. Copeia, 1969, 2: 370-373.
Buchanan, J. P. 1968. A meristic and morphometric comparison of Arkansas largemouth bass, Micropterus sal-
moides salmoides (Lacepede), and the Florida subspecies, Micropterus salmoides floridanus (Lesueur). M.
S. Thesis. LJniv. of Arkansas, Fayetteville, Arkansas. 45 p.
1973. Separation of the subspecies of largemouth bass, Micropterus salmoides salmoides, and M. s.
floridanus and intergrades by use of meristic characters. Proc. 27th Ann. Conf. Southeast. Assoc. Game Fish
Comm. pp. 608-619.
Chew, R. L. 1975. The Florida largemouth bass. Pages 450-^58 in H. Clepper, ed. Black bass biology and
management. Nat. Symp. Biol. Mgmt. Centrar. Basses. Sport Fishing Inst. Washington, D. C. 534 p.
Colby, P. J. 1973. Response of the alewives, Alosa pseudoharengus, to environmental change. Pages 163-196 in
W. Chavin, ed. Responses of fish to environmental change. Charles C. Thomas, Publisher. Springfield, Illinois:
459 p.
Childers, W. F. 1975. Bass genetics as applied to culture and management. Pages 362-372 in H. Clepper, ed. Black
bass biology and management. Nat. Symp. Biol. Mgmt. Centrar. Basses, Sport Fishing Inst. Washington D. C.
534 p.
Dixon, W. ). 1976. Biomedical computer programs. University of California Press. Berkeley. 773 p.
Goldberg, E. 1966. Lactate dehydrogenase of trout: Hybridization in vivo and in vitro. Science, 151: 1091-1093.
Gottlieb, L. D. 1971. Gel electrophoresis: New approach in the study of evolution. BioScience, 21: (18): 939-944.
Hart, ). S. 1952. Geographical variations of some physiological and morphological characters in certain freshwater
fish. Univ. Toronto Biol. Ser., 60: 1-79.
Hayden, R. P. 1966. Estimated angler use and harvest, Isabella Reservoir, Kern County, California. Calif. Fish Game,
Inland Fish. Admin. Rep. No. 66-7, 11 p. (mimeo.)
Hochachka, P. W., and G. N. Somero. 1971. Biochemical adaptation to the environment. Pages 99-156 in W. S.
Hoar and D. ). Randall, eds. Fish Physiology. Academic Press. New York. 559 p.
1973. Strategies of biochemical adaptations. W. B. Saunders Co., Philadelphia. 358 p.
Hubbs, C. L., and L. C. Hubbs. 1930. Increased growth in hybrid sunfishes. Papers Michigan Acad. Sci. Arts Letters
13: 291.
Hubbs, C. L., and K. F. Lagler. 1949. Fishes of the Great Lakes region. Bull. No. 26. Cranbrook Institute of Science.
Bloomfield Hills, Michigan. 186 p.
Johnson, D. L. 1975. A comparison of Florida and northern largemouth bass in Missouri, Ph.D. Thesis, Univ. of
Missouri. Columbia, Missouri. 1 11 p.
Metcalf, R. A., G. S. Whitt, and W. F. Childers. 1972. Inheritance of esterases in the white crappie (Pomoxis
annularis), black crappie (P. nigromaculatus) and their F, and Fj interspecific hybrids. Anim. Blood Grps.
Biochem. Genet., 3: 19-33.
Pelzman, R. )., S. A. Rapp, and R. R. Rawstron. 1980. Mortality and survival of tagged smallmouth bass, Micropterus
dolomieui, at Merle Collins Reservoir, California. Calif. Fish Game, 66(1): 31-35.
Rieger, P. W., R. C. Summerfelt, and G. E. Gebhart. 1978. Catchabiiity of northern and Florida largemouth bass
in ponds. Prog. Fish-Cult. 40(3): 94-97.
Sasaki, S. 1961. Introduction of Florida largemouth bass into San Diego County. Calif. Fish Game, Inland Fish.
Admin. Rep. No. 61-11, 6 p.
Shebley, W. H. 1917. History of the introduction of food and game fishes into the waters of California. Calif. Fish
Game, 3(1): 3-12.
Shull, G. H. 1948. What is "heterosis?" Genetics 33: 439.
Umbarger, H. E. 1961. Quoted in. J. H. Wilkinson. 1970. Isoenzymes. J. B. Lippincott Co. Philadelphia. 369 p.
Umbarger not seen.
Utter, F. M., and F. W. Allendorf. 1977. Determination of the breeding structure of steelhead populations through
gene frequency analysis. Pages 44-54 in J. J. Hassler and R. R. VanKirk, eds. Genetic implications of steelhead
management. Coop. Fish. Res. Unit. Spec. Rep. 77-1. 57 p.
162 CALIFORNIA FISH AND CAME
Utter, F. M., H. O. Hodgins, and F. W. Allendorf. 1974. Biochemical genetic studies of fishes: potentialities and
limitations. Pages 213-238 in D. C. Malins and J. R. Sargent, eds. Biochemical and biophysical perspectives
in marine biology. Academic Press. London, New York, and San Francisco. Vol. 1. J
Wheat, T. E., W. F. Childers, and C. S. Whitt. 1974. Biochemical genetics of hybrid sunfish: differential survival '
of heterozygotes. Biochem. Genet. 11(3); 205-219.
Wheat, T. E., C. S. Whitt, and W. F. Childers. 1973. Linkage relationships of six enzyme loci in interspecific sunfish
hybrids (genus Lepomis) . Genetics, 74: 343-350.
Whitt, G. S., W. F. Childers, and P. L. Cho. 1973. Allelic expression at enzyme loci in an intertribal hybrid sunfish.
J. Hered., 64: 55-61.
Whitt, G. S., W. F. Childers, J. Tranquilli, and M. Champion. 1973. Extensive heterozygosity at three enzyme loci
in hybrid sunfish populations. Biochem. Genet., 8(1): 55-72.
Whitt, G. S., W. F. Childers, and T. E. Wheat. 1971. The inheritance of tissue-specific lactate dehydrogenase
isozymes in interspecific bass (Micropterus) hybrids. Biochem. Genet., 5: 257-273.
Zolczynski, S. )., Jr., and W. D. Davies. 1976. Growth characteristics of the northern and Florida subspecies of
largemouth bass and their hybrid, and a comparison of catachibility between the subspecies. Am. Fish. Soc,
Trans., 105(2): 240-243.
BLACK BASS POPULATION DYNAMICS 163
Calif. Fish and Came 66 ( 3 ) : 1 63-1 7 1
EXPLOITATION, NATURAL MORTALITY, AND SURVIVAL
OF SMALLMOUTH BASS AND LARGEMOUTH BASS IN
SHASTA LAKE, CALIFORNIA ^
WILLIAM F. VAN WOERT
California Department of Fish and Ganne
627 Cypress Avenue
Redding, CA 96001
To obtain information on mortaility and survival of black bass in Shasta Lake, $5
reward trailer tags were attached to smallmouth bass, Micropterus dolomieui, in
1973 and 1975 and to largemouth bass, M. salmoides, in 1975.
First-year exploitation of 203 to 356 mm (8 to 14 in.) smallmouth bass tagged in
1973 was 0.68, natural mortality was 0.24, and survival was 0.08. First-year exploitation
of 254- to 305-mm (10- to 12-in.) smallmouth bass tagged in 1975 was 0.70, natural
mortality was 0.28, and survival was 0.02. First-year exploitation of 254- to 406-mm
(10- to 16-in.) largemouth bass tagged in 1975 was 0.50, natural mortality 0.28, and
survival 0.22.
First-year exploitation of both species probably was lower than that indicated by
tag returns since anglers were known to release some small bass after removing the
tag. Survival of both species may have been underestimated since high turbidity
levels in 1974 and the beginning of a 2-year drought in 1976 may have reduced angler
use and/or success.
High exploitation of smallmouth bass in Shasta Lake is the result of heavy angling
pressure and high vulnerability of young smallmouth bass to natural baits. This high
exploitation appears to be responsible for the large population of small smallmouth
bass in Shasta Lake.
INTRODUCTION
Fishery management efforts at Shasta Lake have centered primarily on the
stocking of salmonids large enough to utilize the large population of threadfin
shad, Dorosoma petenense, (Weidlein 1971 ), but a substantial warmwater fish-
ery is also present. Largemouth bass were introduced in 1948 and smallmouth
bass in 1952. Largemouth bass fishing was excellent in the 1950's and early
1960's, but more recently, largemouth bass fishing has declined. Smallmouth
bass have become the most frequently caught warmwater species (Weidlein
1971 ). In 1973, smallmouth bass outnumbered largemouth bass in the catch by
about 13 to 1 (Healey, MS9).
Weidlein (1971) noted a decline in both total catch and catch/h of small-
mouth bass in Shasta Lake from 1968 to 1969 and recommended that the fishery
be closely examined to see if this species was being overharvested. Creel checks
conducted in 1968 and 1969 (Weidlein, unpubl. data) and 1972 and 1973 (Van
Woert, unpubl. data) showed that the mean length of smallmouth bass in the
catch ranged from 274 to 287 mm ( 1 0.8 to 1 1 .3 in. ) . During these 4 years, 64.3%
to 74.5% of the smallmouth bass in the catch were under 305 mm (12 in.).
Relatively few smallmouth bass larger than 356 mm (14 in.) entered the catch
or were found during electrofishing surveys.
Studies by Rawstron (1967), Rawstron and Hashagen (1972), and Rawstron
" Accepted for publication February 1980. Parts of this study were performed as part of Dingell-Johnson project
California F-34-R, "Experimental Warmwater Reservoir Management", supported by Federal Aid to Fish
Restoration funds.
164 CALIFORNIA FISH AND CAME
and Reavis (1974) showed that largemouth bass were heavily exploited in some
California waters; however, mortality and survival of smallmouth bass have
received little attention in California. Rawstron's (1967) findings also suggested
that the harvest of smallmouth bass might be as high or higher than that of
largemouth bass in Folsom Lake.
As part of a program designed to collect the basic biological information
needed to develop a management plan for warmwater fishes, smallmouth bass
were tagged in Shasta Lake in 1973 and both smallmouth and largemouth bass
tagged in 1975 to determine exploitation, natural mortality, and survival rates.
Smallmouth bass were tagged in 1975 to obtain comparable estimates of mortal-
ity and survival for 254- to 305-mm (10- to 12-in.) smallmouth and largemouth
bass in the Pit River Arm of Shasta Lake and for comparison with smallmouth
estimates obtained in 1973 in the Sacramento River Arm of Shasta Lake. The
tagging studies would provide the information needed to evaluate current an-
gling regulations, particularly the bag limit and possible need for a minimum
length limit. This report summarizes the results of the 1973 and 1975 tagging
studies and discusses some future management possibilities for black bass in
Shasta Lake.
DESCRIPTION OF SHASTA LAKE
Shasta Lake is located on the Sacramento River 11 km (7 miles) upstream
from Redding, Shasta County, California (Figure 1). Completed in the early
1940's, this reservoir is operated by the U.S. Water and Power Resource Service
for irrigation, power generation, and flood control.
Shasta Lake has three long, narrow arms named for its major tributaries; the
Sacramento, McCloud, and Pit Rivers. At full pool the Lake has a surface eleva-
tion of 325 m (1,067 ft), impounds 5,551 hm^ (4.5 million acre-ft) of water,
covers 11,947 ha (29,500 acres), and has 587 km (365 miles) of shoreline.
Maximum water storage is generally reached about May and summer draw-
down begins by early June.
Surface water temperatures range from about 10°C (50°F) in winter to 27°C
(80°F) in summer. Thermal stratification takes place usually in June. Lake margins
have mostly moderately steep to steep slopes, with very little vegetation in the
fluctuation zone.
Shasta Lake is open year-round to fishing for all species. Daily bag limit during
the study was five black bass, with no minimum length limit. Boat anglers have
good access to the Lake from numerous public boat launching ramps and
privately-owned resorts. A relatively small portion of the shore is accessible by
road for shore fishing.
METHODS
Tagging studies were designed to study each major arm of the Lake separately
because of Shasta Lake's large size. Smallmouth and largemouth bass were
tagged by length groups and returns analyzed by length groups and age classes
in an effort to determine an optimum length limit by evaluating the effects of
incremental increases in minimum length on maximum yield. All bass were
collected with an electrofishing boat usually operated within 3 m (9.8 ft) of the
shore and in water under 2 m (6.6 ft) deep. Pulsating direct current was used.
BLACK BASS POPULATION DYNAMICS
165
FIGURE 1. Shasta Lake showing areas where black bass were tagged in 1973 and 1975.
166 CALIFORNIA FISH AND CAME
All electrofishing was done at night during March, April, and May.
In 1973, electrofishing was conducted along 156 km (97 miles) of shoreline
in the Sacramento River Arm in an effort to tag 203- to 356-mm (8- to 14-in.)
smallmouth bass.
In 1975, electrofishing was conducted along 208 km (129 miles) of shoreline
in the Pit River Arm in an effort to tag 254- to 406-mm ( 1 0- to 1 6- in. ) largemouth
bass and 254- to 305-mm (10- to 12-in.) smallmouth bass.
Smallmouth bass larger than 356 mm ( 1 4 in. ) were not tagged in 1 973 because
previous bass tagging studies in California suggested that too few large bass
would be tagged to give significant returns after the second year. Early electro-
fishing in 1975 indicated that few largemouth bass under 254 mm (10 in.) were
available for tagging while largemouth bass 356 to 406 mm (14 to 16 in.) were
fairly abundant. Only 254- to 305-mm (10- to 12-in.) smallmouth bass were
tagged in 1975 because of limited reward tag funds.
As the electrofishing boat moved along the shoreline, stunned bass were
netted, measured to the nearest 2.54 mm (0.1 in.), tagged, and a scale sample,
for use in aging fish, taken near the tip of the pectoral fin. Stunned bass generally
recovered in less than 5 minutes and were released as soon as they appeared
to be recovered. An effort was made to release tagged bass close to where they
had been captured.
All bass were tagged with trailer tags. The method of attachment was de-
scribed by Nicola and Cordone (1969). Tags used in this study were 16-mm
(Vs-in.) long, 6-mm (y4-in.) wide, 0.8-mm (.030-in.) thick, and made of laminat-
ed green vinyl plastic. Tags had a number and $5 REWARD on one side and
instructions for returning the tag on the other side. Tag frame and link were made
of 0.3-mm (.012-in.) diameter soft stainless steel wire.
Bass caught from zero through 365 days from the date of tagging were consid-
ered first-year returns. Bass caught from 366 to 730 days and 731 to 1,095 days
after the date of tagging were considered second- and third-year returns, respec-
tively. The computation of mortality and survival rates follow Ricker (1958).
Age determinations were made by counting annuli on scale impressions made
on cellulose acetate strips with the aid of a binocular microscope and an Eber-
bach scale projector.
RESULTS
Smallmouth Bass — 1973
Between 8 March and 25 April 1973, 530 smallmouth bass were tagged in the
Sacramento Arm of Shasta Lake. Anglers returned a total of 391 ( 73.8% ) of these
tags within 3 years. Only first- and second-year tag returns were used in calcula-
tions of mortality and survival because muddy water in 1 974 may have adversely
affected fishing success. Since no tags were returned during the fourth year, tag
returns were considered complete. First-year exploitation for all length groups
combined amounted to 0.68, natural mortality was 0.24, and survival from the
first to the second year was 0.08 (Table 1 ).
When calculated for 25.4-mm (1-in.) length groups, first-year exploitation
increased from 0.59 to 0.79 for bass 203 mm (8 in.) to 279 mm (11 in.) and
decreased from 0.79 to 0.52 for fish 279 mm (11 in.) to 356 mm (14 in.) (Table
BLACK BASS POPULATION DYNAMICS
167
.1 ) . A chi-square test of homogeneity showed a significant difference in exploita-
tion by length at the 5% level (X' = 18.78; d.f. = 5; p<0.01 ).
Analysis by age class showed that younger smallmouth bass were exploited
at higher rates than older fish (Table 2). First-year exploitation amounted to 0.72
for Age II, 0.58 for Age III, and 0.47 for Age IV fish. Length at any given age was
highly variable. Age II smallmouth bass ranged from 208 to 307 mm (8.2 to 12.1
in.) and averaged 254 mm (10.0 in.). Age III fish ranged from 221 to 350 mm
(8.7 to 13.8 in.) and averaged 305 mm (12.0 in.). Age IV smallmouth bass were
incompletely represented in the study since only fish under 356 mm (14 in.)
were tagged.
TABLE
1. Exploita
tion, Natl
jral Mor
talitv, and
1 Survival (
of Tagg
ed Smallmouth Bass
by Length
Croups
in 1973 at Shasta Lake.
Number of tags
Foi
■k Length
tagging
Number
tagged
returned
First-year
exploitation
Natural
mortality
Annual
at
First
Second
Third
survival *
(mm)
1973
year
year
year
Total
(u)
(v)
(s)
203-228 ,
44
26
2
_
28
0.59
0.34
0.07
229-253 .
156
133
109
105
9
4
1
118
110
0.70
0.79
0.22
0.17
0.08
254-279 .
0.04
28(^305 .
67
47
3
1
51
0.70
0.24
0.06
30^330 .
67
41
4
-
45
0.61
0.30
0.10
331-356 ,
63
33
6
-
39
0.52
0.30
0.18
Total 530 361 28
Mean _ _ _
' Based on ratio of second-year to first-year returns.
391
0.68
0.24
0.08
TABLE 2. Exploitation, Natural Mortality, and Survival of Tagged Smallmouth Bass by Age
Classes in 1973 at Shasta Lake.
Ill
Number
tagged
1973
Number of tags
returned
Total
First-year
exploitation
(u)
Natural
mortality
(v)
Annual
Age
First Second
year year
Third
year
survival *
(s)
II
... 254
... 305
346
70
45
250 16
41 6
21 3
1
1
48
24
0.72
0.58
0.47
0.21
0.27
0.40
0.07
Ill
0.15
IV t
0.14
Total - 461 X 312 25 2 339
* Based on ratio of second-year returns to first-year returns.
t Age group incompletely sannpled because bass over 356 mm (14.0 in.) were not tagged.
X Scales in 69 samples could not be aged.
Snnallnnouth Bass — 1975
Between 11 March and 9 May 1975, 200 smallmouth bass were tagged in the
Pit River Arm of Shasta Lake. Anglers returned a total of 1 43 (71 .5% ) of the tags
within 2 years after tagging (Table 3). Since no tags were returned during the
third year, tag returns were considered complete. Total first-year exploitation
was 0.70, natural mortality was 0.28, and survival from the first to the second
year was 0.02. Mortality and survival rates by age class were not calculated for
this group of fish because of the narrow length range of fish tagged.
168
CALIFORNIA FISH AND GAME
TABLE 3. Exploitation, Natural Mortality, and Survival of Tagged Smallmouth Bass by Length
Groups in 1975 at Shasta Lake.
Number of
Fork length
at tagging
(mm)
Number
tagged
1975
tags
returned
First Second
year year
254-279..
280-305..
100
100
73
68
2
Total
First-year Natural Annual
exploitation mortality survival*
(u) (v) (s)
73 0.73 0.27 0.0
70 0.68 0.29 0.03
Total 200 141 2 143
Mean _ _ _ - 0.70 0.28 0.02
* Based on ratio of second-year to first-year returns.
Largemouth Bass — 1975
Between 11 March and 9 May 1975, 461 largemouth bass were tagged in the
Pit River Arm of Shasta Lake. Anglers returned a total of 309 (67.0%) tags within
5 years after tagging. Only first- and second-year tag returns were used in
calculations of mortality and survival because of possible changes in fishing use
and/or success during the 1 976-77 drought. Total first-year exploitation amount-
ed to 0.50, natural mortality was 0.28, and survival was 0.22 (Table 4).
A chi-square test of homogeneity showed no significant difference in exploita-
tion by length groups at the 5% level (X' = 3.06; d.f. = 5; p = -0.69).
Natural mortality showed considerable variation among length groups, rang-
ing from 0.15 for fish 331 to 356 mm (13 to 14 in.) to 0.35 for fish 306 to 330
mm (12 to 13 in.) (Table 4).
TABLE 4.
Fork Length
at tagging
(mm)
Exploitation, Natural Mortality and Survival of Tagged Largemouth Bass by Length
Groups in 1975 at Shasta Lake.
Number
tagged
1975
First
year
Number of tags returned
Second
year
Third
year
Fourth
year
First- Natural Annual
Fifth year mortality survival *
year Total exploitation (v) (s)
254-279 68 38 4 3 - 1 46 0.56 0.34 0.10
280-305 100 51 10 3 - 1 65 0.51 0.29 0.20
306-330 100 52 7 1 1 3 64 0.52 0.35 0.13
331-356 67 31 12 4 - 1 48 0.46 0.15 0.39
357-381 72 33 9 3 1 - 46 0.46 0.27 0.27
382-406 54 23 9 6 1 1 40 0.43 0.18 0.39
Total 461 228 51 20 3 7 309 1 0.50
Mean _______ _ o.28 0.22
* Based on ratio of second-year to first-year returns.
t Returns through January 1980.
Analysis by age class showed a 0.51 and 0.50 first-year exploitation for Age
II and Age III largemouth bass, respectively (Table 5). Age IV and V fish were
incompletely represented in the study because only fish under 406 mm (16 in.)
were tagged. Some small Age II fish may not have been included in the study
since fish under 254 mm (10 in.) were not tagged.
Age II largemouth bass ranged from 254 to 353 mm (10.0 to 13.9 in.) and
averaged 300 mm (11.8 in.) in length. Age III largemouth bass ranged from 300
to 401 mm (11.8 to 15.8 in.) and averaged 358 mm (14.1 in.).
BLACK BASS POPULATION DYNAMICS 169
TABLE 5. Exploitation, Natural Mortality, and Survival of Tagged Largemouth Bass by Age
Classes in 1975 at Shasta Lake.
Mean Number Number of tags returned First- Natural Annual
length tagged First Second Third Fourth Fifth year mortality survival *
Age (mm) 1975 year year year year year Total exploitation (v) (s)
II
300
271
139
24
10
1
6
180
0.51
0.32
0.17
Ill
358
110
43
55
15
14
8
5
4
1
1
1
75
29
0.50
0.35
0.25
0.12
0.25
IV t
0.53
vt
-
2
1
-
-
-
-
1
-
-
-
Total - 426 1 210 46 19 3 7 285
• Based on ratio of second-year returns to first-year returns.
t Age group incompletely sampled because bass over 406 mm (16.0 in.) were not tagged.
X Scale samples from 35 fish could not be aged.
DISCUSSION
Exploitation rates of smallmouth bass in Shasta Lake appear to be nnuch higher
than those reported by Coble (1975) for northern lake populations of this
species.
Annual fishing mortality rates compiled by Coble (1975) (assumed by the
author to be "m" as defined in Ricker 1958) show fishing mortalities of 28 to
35 for the Great Lakes (Latta 1963, Fry 1964, and White 1970), 35% for Oneida
Lake (Forney 1972) and 38% for Lake Opeongo (Christie 1957). Annual fishing
mortality (m) of smallmouth bass in Shasta Lake, computed for fish tagged in
1973, was 85%. However, this figure may be an over-estimate since in order to
obtain an accurate estimate of annual fishing mortality, fishing effort and catcha-
biiity should remain constant during the study period. In the case of smallmouth
bass tagged in 1973, effort was down by 31% in 1974 as compared to 1973,
(USDA 1973-1977) with vastly different water conditions. During the spring of
1973, water was relatively clear, while in the spring of 1974 the water was turbid
because of large inflows during the winter. Also, the number of smallmouth bass
observed in the catch during 1974 was down 27% over 1973 (Healey, MS).
Creel census effort each year was comparable.
An annual expectation of death from fishing for smallmouth bass tagged in
1973 (first-year exploitation, u) of 68% was a more accurate estimate of fishing
mortality, and still indicated that exploitation of smallmouth bass in Shasta Lake
was considerably higher than that reported for northern populations.
First-year exploitation of largemouth bass (50%) in Shasta Lake was similar
to that reported for other California waters. Exploitation of largemouth bass was
40% in Folsom Lake (Rawstron 1967), 49% in Merle Collins Reservoir (Raw-
stron and Hashagen 1972), and 47% and 58% in Folsom Lake and Lake Berry-
essa, respectively (Rawstron and Reavis 1974). These authors consider
exploitation rates over 0.50 to be excessive for black bass (R. R. Rawstron, Fish
Mgmt Supervisor, Calif. Dept. Fish and Game, pers. commun. ) . In small Missouri
lakes and ponds, a 40% harvest of adult largemouth bass appeared to be the
maximum that could be allowed and still maintain a balanced sunfish population
and adequate growth and recruitment of bass (Graham 1974, Ming 1974, and
Redmond 1974). Preliminary results of tagging studies in progress at Shasta Lake
show that many anglers release largemouth bass, particularly fish under 305 mm
170 CALIFORNIA FISH AND CAME
(12 in.), although there is no minimum length limit. Since no adjustment of
exploitation rates was made for fish released at Shasta Lake and apparently was
not made for earlier tagging studies conducted on largemouth bass in California,
the true rate of exploitation of largemouth bass populations studied in California
waters was probably somewhat less than that computed from tag returns.
About 60% of the anglers checked at Shasta Lake between April and Septem-
ber 1973, fishing for species other than trout, were found to be using natural baits
(Van Woert, unpubl. data). These anglers caught 71% of the smallmouth bass
and 9% of the largemouth bass in the creel samples. Anglers who used only
crickets for bait caught 42% of the smallmouth bass and 3% of the largemouth
bass sampled, while those using artificial lures caught 78% of the largemouth
bass observed. In recent years, overexploited bass populations in many Califor-
nia waters have been managed by the imposition of a 305-mm ( 1 2-in. ) minimum
length limit.
A minimum length limit may not be an efficient means of reducing exploitation
of smallmouth bass at Shasta Lake because the extensive use of natural baits may
result in excessive hooking mortality. Pelzman (1978) observed a 56% mortality
of largemouth bass less than 305 mm (12 in.) as a result of esophageal hooking;
however, fish hooked in other parts of the mouth experienced little mortality.
First-year exploitation of largemouth bass (0.53) between 254 and 305 mm
(10 and 12 in.) tagged in 1975 was substantially lower than that for smallmouth
bass (0.70) of the same size tagged the same year. Some of this difference in
exploitation may be caused by the difference in vulnerability of the two species
to the different angling techniques noted above. Hooking mortality probably
would not be a critical factor in imposing a length limit on largemouth bass since
this species is caught mainly (78%) on artificial lures (Van Woert, unpubl.
data).
While high exploitation resulted in a small average size of smallmouth bass
in the catch at Shasta Lake, recruitment generally was good and smallmouth bass
were abundant during most years. Since smallmouth bass were relatively easy
to catch on natural bait, they helped satisfy a high angling demand during the
spring and summer months. Any attempt to improve the quality of smallmouth
bass fishing by protecting smallmouth bass until they reach larger sizes may
require restrictions on bait, as well as a minimum length limit.
Although smallmouth and largemouth bass may be overexploited in Shasta
Lake, there does not appear to be a serious imbalance between bass and sunfish
populations. Electrofishing surveys indicate that recruitment of bluegill, Lepomis
machrochirus, and green sunfish, L. cyanellus, is low. Analysis of stomach con-
tents indicate that bass in Shasta Lake rely more heavily upon threadfin shad as
a food source than upon other sunfishes. Examination of scales has shown that
black bass appear to be achieving normal growth patterns in Shasta Lake
(Charles E. von Geldern, Jr., Sr. Fish. Biologist, Calif. Dept. Fish and Game, pers.
commun.).
Electrofishing surveys conducted at Shasta Lake indicated that recruitment of
largemouth bass is low. To increase production and survival of young
largemouth bass in Shasta Lake, bass spawning and nursery habitat should be
restored. If efforts to enhance shelter for largemouth bass are not feasible, the
BLACK BASS POPULATION DYNAMICS 171
combination of low recruitment, good growth, and high exploitation strongly
suggests that a minimum length limit would provide better fishing for largemouth
bass.
ACKNOWLEDGMENTS
I wish to thank Don Weidlein for his assistance in planning the study, help in
the field, and review of the manuscript. Charles E. von Geldern, Jr. had impres-
sions made of the scales and provided the initial age determinations. Robert R.
Rawstron, Alan Baracco, and Darlene Osborne made valuable suggestions re-
garding preparation of this report and reviewed the manuscript. Terrance P.
Healey, David A. Hoopaugh, and various temporary employees helped with the
tagging and electrofishing operations.
REFERENCES
Christie, W. J. 1957. The bass fishery of Lake Opeongo. M. A. thesis. Univ. of Toronto, 77 p.
Coble, D. W. 1975. Smallmouth bass. Pages 21-33 in Henry Clepper, ed. Black bass biology and management.
Sport. Fish. Inst.
Forney, J. L. 1 961 . Growth, movements, and survival of smallmouth bass ( Micropterus dolomieuf) in Oneida Lake,
New York. N.Y. Fish Came J., 8(2): 88-105.
1972. Biology and management of smallmouth bass in Oneida Lake, New York. N.Y. Fish Came J., 19(2):
132-154.
Fry, F. E. ). 1964. Anglers arithmetic. Pages 55-71 in\. R. Dymond, ed. Fish and Wildlife. T. H. Best Printing Co.,
Toronto, Canada, 214 p.
Graham, L. K. 1974. Effects of four harvest rates on pond fish populations. Pages 29-38 in symposium on
overharvest and management of largemouth bass in small impoundments. N.C. Div., Amer. Fish. Soc. Spec.
Pub. (3).
Healey, T. P. 1977. A review of Whiskeytown Lake fishery management from 1963-1975. Calif. Dept. Fish and
Came, Inland Fish. Adm. Rep. 77-2, 24 p. (mimeo).
Latta, W. C. 1963. The life history of the smallmouth bass, Micropterus d. dolomieui, at Waugoshance Point, Lake
Michigan. Mich. Dept. Conserv. Inst. Fish. Res. Bull. No. 5, 56 p.
Ming, A. 1974. Regulation of largemouth bass harvest with a quota. Pages 39-53 in symposium on overharvest
and management of largemouth bass in small impoundments. N.C. Div., Amer. Fish. Soc. Spec. Pub. 3.
Nicola, S. )., and A. ). Cordone. 1969. Comparisons of disk-dangler, trailer, and plastic jaw tags. Calif. Fish Game,
55(4): 273-284.
Pelzman, R. ). 1978. Hooking mortality of largemouth bass (Micropterus salmoides) less than 305 mm long. Calif.
Fish Came, 64(3): 185-188.
Rawstron, R. R. 1967. Harvest, mortality, and movement of selected warmwater fishes in Folsom Lake, California.
Calif. Fish Came, 53(1); 40-48.
Rawstron, R. R., and K. A. Hashagen, )r. 1972. Mortality and survival rates of tagged largemouth bass (Micropterus
salmoides) at Merle Collins Reservoir. Calif. Fish Came, 58(3): 221-230.
Rawstron, R. R., and R. A. Reavis. 1974. First-year harvest rates of largemouth bass at Folsom Lake and Lake
Berryessa, California. Calif. Fish Game, 60(1): 52-53.
Redmond, L. C. 1974. Prevention of overharvest of largemouth bass in Missouri impoundments. Pages 54-68 In
symposium on harvest and management of largemouth bass in small impoundments. N.C. Div., Amer. Fish.
Soc. Spec. Pub. (3): 54-68.
Ricker, W. E. 1958. Handbook of computations for biological statistics offish populations. Can., Fish. Res. Bd., Bull.
(119): 300 p.
USDA Forest Service. 1973-1977. Annual recreational use reports. Shasta-Trinity National Forest, Redding, CA.
Weidlein, W. D. 1 971 . Summary progress report on the Shasta Lake trout management investigations, 1 967 through
1970. Calif. Dept. Fish and Game, Inland Fish. Adm. Rep. 71-13, 25 p. (mimeo).
White, W. J. 1 970. A study of a population of smallmouth bass ( Micropterus dolomieuf) , Lacepede at Bale du Dore,
Ontario, M. S. thesis. Univ. of Toronto, 83 p.
172 CALIFORNIA FISH AND GAME
Calif. Fish and Came 66 ( 3 ) : 172-177
DIET AND BEHAVIORAL ASPECTS OF THE WOLF-EEL,
ANARRHICHTHYS OCELLATUS, ON SANDY BOTTOM IN
MONTEREY BAY, CALIFORNIA ^
LARRY W. HULBERC ^ AND PATSY GRABER ^
Moss Landing Marine Laboratories
P.O. Box 223
Moss Landing, California 95039
We studied the diet and behavior of wolf-eels occurring near artificial structures
on a sandy bottom in Monterey Bay, California, to obtain information about their
biology and natural history. Diet was determined by examining stomach contents.
The principal prey items consumed were the slender crab. Cancer gracilis, and the
sand dollar, Dendraster excentricus. Other species were of minor importance in their
diet. Our data suggest that wolf-eels, in our study area, are nocturnal predators
which forage over wide areas for food.
Scuba divers observed wolf-eel behavior. The individuals observed displayed
strong territorial, homing, and itinerant behaviors.
Based on the numbers of individuals collected and observed at our stations, the
wolf-eel population of Monterey Bay may be quite large.
INTRODUCTION
We examined the diet and behavior of a population of wolf-eels on a subtidal
sandy bottom in Monterey Bay, California, to obtain information about the
biology and natural history of the species.
Wolf-eels occur in shallow areas along the west coast of North America from
Imperial Beach in southern California (Radovich 1961), through Oregon and
Washington (Schultz and DeLacy 1936), and as far north as the Aleutians
(Quast and Hall 1972). A few specimens have been reported as far west as the
Sea of Okhotsk and the Sea of Japan ( Popov 1 933, Schmidt 1 965 ) . They inhabit
relatively shallow rocky areas (Gill 1911; Schultz 1930; Barsukov 1959; Miller
and Gotshall 1965; Burge and Schultz 1973, p. 161 ) although Fitch and Laven-
berg (1971 ) reported a specimen caught as deep as 400 ft. The sandy bottom
environment of the population in this study is a habitat not previously reported
for wolf-eels in the Pacific.
MATERIALS AND METHODS
Twenty-five wolf-eels were collected randomly from August 1 974 to July 1 975
by scuba divers using hand spears. All specimens were obtained from two sites
in central Monterey Bay at Moss Landing, California (Figure 1 ). The collecting
sites were permanent stations established on sandy bottom in 18 m and 24 m
of water where various artificial structures had been emplaced. They were
designated M-4 and M-5, respectively. All specimens were collected during the
morning hours, generally between 0700 and 1 100 h. Most were collected during
August 1974 and June and July 1975.
' Accepted for publication October 1979.
^ Present address: Holmes & Narver, Inc., Antarctic Division, 999 Town & Country Road, Orange, CA 92668.
' Present address; P.O. Box 107, Moss Landing, CA 95039.
WOLF-EEL DIET AND BEHAVIOR
173
DEPTH CONTOURS IN METERS
FIGURE 1. Anarrhichthys ocellatus collecting sites M-4 and fv1-5.
All wolf-eels were weighed and measured (standard length). Their stomachs
were removed, fixed in 10% formalin, and later stored in 50% isopropyl alcohol.
Subsequently, prey items were identified to the lowest taxa possible and their
174 CALIFORNIA FISH AND GAME
volumes determined by liquid displacement. Since stomach contents consisted
primarily of hard parts of ingested prey, they were reassembled as much as
possible to determine the total number of whole individuals consumed.
An index of relative importance (IRI) (Pinkas, Oliphant, and Iverson 1971 )
was used to show the total contribution of each prey species to the diet of the
wolf-eel. This index was calculated as IRI =FO (N+V) where N is the numeri-
cal percentage a food type contributed to the total diet, V is its volumetric
percentage, and FO is its percent frequency of occurrence (that proportion of
stomachs containing the food item). To calculate this index, data from all
specimens were combined and treated as a single sample.
Behavioral aspects of wolf-eels were observed by scuba divers during approx-
imately 100 dives. In addition, seven specimens were tagged to document
behavior patterns of specific individuals.
RESULTS AND DISCUSSION
The specimens obtained ranged from 109 to 145 cm length (X — 131 cm).
Their weights ranged from 1400 to 4230 g (X ==2977 g), with much variation
depending upon the amount of food present in the stomachs.
The slender crab. Cancer gracilis, was the most frequently consumed species
and, by far, the most important volumetrically (Figure 2). The sand dollar,
Dendraster excentricus, was occasionally consumed in large numbers. Other
items were taken less frequently (Table 1 ). The only evidence of fish predation
was the presence of several fish vertebrae in the stomach of a single specimen.
The stomachs of most wolf-eels contained an appreciable amount of food; only
four wolf-eels had empty stomachs.
In general, our findings on the diet of A. ocellatus agree with those of other
studies. Clemens and Wilby (1961 ) reported a diet of crustaceans, sea urchins,
mussels, clams, and other hard shelled invertebrates as v/ell as fishes; Fitch and
Lavenberg (1971 ) reported a preponderance of crab remains in the stomachs,
and also found sea urchin fragments, small snails including abalones, and an
occasional piece of fish; Jordan and Evermann (1898) found stomachs contain-
ing sea urchins and sand dollars; Jordan and Starks (1895) reported a diet of
chiefly crustaceans and mussels. In our study, however, bivalves and gastopods
were taken rarely.
Wolf-eels probably forage over large areas for Cancer spp. because we did
not observe many large crabs during hundreds of day and night dives in our
study area for another project. We did observe an abundance of small flatfishes
in the area but, evidently they were not a major food item (Table 1 ) . Apparently,
A. ocellatus is capable of capturing only relatively slow moving prey on an open
sandy bottom. Fishes may be easier prey in rocky areas where they might be
trapped more readily.
Of nearly 50 wolf-eels observed, all were sedentary (but alert) and in close
proximity to an artificial structure. They were never observed on an open sandy
bottom away from structures. Thus, there appears to be strong attraction to
structures of some kind. In addition, all individuals observed exhibited strong
territoriality. When a wolf-eel was approached it would rear its head back and
open its mouth to prominently display its teeth. It would continue this aggressive
display for several minutes, occasionally advancing toward the intruder in a
WOLF-EEL DIET AND BEHAVIOR
175
threatening manner. A wolf-eel could be approached to approximately 30 cm
before it would leave. When it did leave the area, it did so at a slow, apparently
unhurried, pace. Despite their aggressive displays, none ever attacked, even
when provoked. They did not possess the viciousness reported by Miller and
Gotshall (1965), nor that reported for related species by Goode (1884).
TABLE 1. Prey Items Consumed by Individual Anarrhichthys ocellatus.
I
2
3
4
5
6
7
8
9
10
I I
12
13
14
15
16
17
18
19
20
21
22
23
24
25
8
II
I I
17
Of seven wolf-eels tagged and released at station M-5, two were observed at
the same location on subsequent dives. One of these was observed in exactly
the same spot (in an open cylinder placed on the bottom) for nearly a month.
176
CALIFORNIA FISH AND GAME
Other individuals, not tagged but recognizable by anatomical characteristics and
scars, were observed at particular sites for up to a month. Wolf-eels probably
forage over wide areas during their occupation of a territory because nearly all
of those collected contained an appreciable amount of food in their stomachs
and the abundance of major prey in any given area was low. By returning
repeatedly to specific sites for periods of several days to several weeks, the fish
displayed a strong homing behavior.
iOOi
C. gracilis
D. excentricus
Octopus
/. pilosus
Bivalves
Po tin ices spp.
— % F 0
% FREQUENCY OF OCCURRENCE
FIGURE 2. Index of relative importance (Pinkas, Oliphant, and Iverson 1971 ) for major prey items
found in Anarrhichthys ocellatus stomachs.
Because all wolf-eels encountered during our daylight (morning) dives were
sedentary and consistently ignored food items (such as crabs) offered to them,
and because most of those collected had relatively full stomachs, we believe that
this species, at least in our study area, is a nocturnal feeder. On the other hand,
they are often caught during the day by hook and line fishermen (Fitch and
Lavenberg 1971 ). Also, because locations vacated by individuals we collected
were reoccupied by other individuals, generally within 1 or 2 days, we conclud-
ed that they are itinerant.
The wolf-eel population in Monterey Bay may be quite large if the numbers
we collected and observed at our stations are any indication of abundance.
WOLF-EEL DIET AND BEHAVIOR 177
ACKNOWLEDGMENTS
Our deepest thanks go to Gregor M. Cailliet for his enthusiasm and support
during the course of this study and his critical review of this paper.
REFERENCES
Barsukov, V. V. 1959. The wolffish (Anarhichadldae). Smithsonian Inst., Washington, D. C. (Transl. from Russian
by the Indian Natl. Sci. Doc. Center, New Delhi) 292 p.
Burge, R. T., and S. A. Schultz. 1973. The marine environment in the vicinity of Diablo Cove with special reference
to abalones and bony fishes. Calif. Dept. Fish and Game, Mar. Res. Tech. Rept. (19) 433 p.
Clemens, W. A., and G. V. Wilby. 1961. Fishes of the Pacific coast of Canada. Fish. Res. Bd. Canada, Bull. (68).
368 p.
Fitch, |. E., and F. J. Lavenberg. 1971. Marine food and game fishes of California. Univ. California Press, Berkeley.
179 p.
Gill, T. 1911. Notes on the structure and habits of the wolffishes. U. S. Nat. Mus., Proc. 39: 157-187.
Goode, G. B. 1884. The fisheries and fishery industries of the United States. Sec. I. Natural history of useful aquatic
animals. U. S. Govt. Printing Office, Washington, D. C. 895 p.
Jordan, D. S., and E. C. Starks. 1895. Fishes of Puget Sound. Proc. Calif. Acad. Acad. Sci. 2(5): 785-855.
Jordan, D. S., and B. W. Evermann. 1898. Fishes of north and middle America. U. S. Nat. Mus., Bull. 47, Part 3:
2183-3136.
Miller, D. J., and D. Gotshall. 1965. Ocean sportfish catch and effort from Oregon to Point Arguello, California.
Calif. Dept. Fish and Game, Fish Bull., (130): 1-135.
Pinkas, L., M. S. Oliphant, and I. L. K. Iverson. 1971 . Food habits of albacore, bluefin tuna, and bonito in California
waters. Calif. Dept. Fish and Game, Fish Bull., (512): 1-105.
Popov, A. M. 1933. Fishes of Avatcha Bay on the southern coast of Kamtchatka. Copeia, 1933: 59-67.
Quast, J. C, and E. L. Hall. 1972. List of fishes of Alaska and adjacent waters with a guide to some of their literature.
NOAA Tech. Rept. NMFS SSRF-658. 47 p.
Radovich, J. 1961. Relationships of some marine organisms of the northeast Pacific to water temperatures. Calif.
Dept. Fish and Came, Fish Bull., (112): 1-62.
Schultz, L. P. 1930. Miscellaneous observations on fishes of Washington. Copeia, 1930: 137-140.
Schultz, L. P., and A. C. DeLacy. 1936. Fishes of the American northwest, a catalogue of the fishes of Washington
and Oregon, with distributional records and bibliography. Pan-Pac. Res. Inst., J, 11: 127-142.
Shmidt, P. Y. 1965. Fishes of the Sea of Okhotsk. Smithsonian Inst, and Nat. Sci. Found., Washington, D. C. (Transl.
from Russian by the Israel Program for Translations.) 392 p.
178 CALIFORNIA FISH AND GAME
Calif. Fish and Came bbii): \78-^8i
DECLINE OF THE LAKE GREENHAVEN
SACRAMENTO PERCH POPULATION
C. DAVID VANICEK
Department of Biological Sciences
California State University, Sacramento
Sacramento, California 95819
Fish populations at Lake Greenhaven were monitored by fall surveys from 1973
through 1978. The Sacramento perch has undergone a decline in abundance, growth,
and condition, and has failed to reproduce in 3 of the last 4 years of the study. Other
species, particularly the bluegill, have increased in abundance since 1973. Competi-
tive interference by the bluegill population is suggested as the primary reason for
the decline of the Sacramento perch population.
INTRODUCTION
Lake Greenhaven is a 24-ha eutrophic lake located in a suburban area in
southwestern Sacramento, California (T8N, R4E). In 1973, the fish population
in this Lake was dominated by the Sacramento perch, Archoplites interruptus,
the only native centrarchid west of the Rocky Mountains ( Aceituno and Vanicek
1976). This species, endemic to the lower Sacramento-San Joaquin drainage
system and the Pajaro and Salinas River systems has undergone a marked
decline in abundance in its native range, although it has been successfully
introduced beyond its original range (Aceituno and Nicola 1976). According to
Aceituno and Nicola (1976), Lake Greenhaven was one of only two natural
waters in the state reported to contain Sacramento perch in both 1955 and 1973
statewide surveys, and it provided the stock for Sacramento perch introductions
to numerous waters in the state by the Department of Fish and Game since 1955
(J. Ryan, Assoc. Fish. Biol., Calif. Dept. of Fish and Game, pers. commun.). This
paper reports on changes that have occurred in the Lake Greenhaven Sacra-
mento perch population since 1973.
DESCRIPTION OF STUDY AREA
Lake Greenhaven, formerly known as Brickyard Pond, was dredged and
enlarged to its present size in 1965 to enhance a new housing development.
Before this alteration, the Lake contained hitch, Lavinia exilicauda; Sacramento
blackfish, Orthodon microlepidotus; carp, Cyprinus carpio; Sacramento perch;
tule perch, Hysterocarpus trash; and sculpin, Cottus sp. Just prior to enlargement
the Lake was chemically treated with rotenone and subsequently restocked with
carp, mosquitofish, Gambus/a aff/nus; channel catfish, Ictalurus punctatus; Sac-
ramento perch; largemouth bass, Micropterus salmoides; and bluegill, Lepomis
macrochirus. In addition, the following species have been found in the Lake:
golden shiner, Notemigonus crysoleucas; white catfish, Ictalurus catus; green
sunfish, Lepomis cyanel I us; and white crappie, Pomoxis annularis. Fishing pres-
sure on the Lake has been very light since 1973.
A description of the Lake's physical and chemical characteristics is provided
by Aceituno and Vanicek ( 1 976) . Water quality analyses conducted in July 1 979
(dissolved oxygen, pH, hardness, alkalinity, and specific conductance) showed
LAKE CREENHAVEN SACRAMENTO PERCH 179
little change in the chemical nature of the water from 1973 conditions, although
secchi disk transparency readings were higher than in 1973 when the water was
turbid due to phytoplankton blooms resulting from the addition of commercial
fertilizer to control submergent vegetation. In 1973 approximately 50% of the
Lake's shoreline had been dredged and rip-rapped; in 1977, work to dredge and
rip-rap the rest of the shoreline began, and by October 1978 virtually all of the
Lake's shoreline had been altered.
METHODS AND MATERIALS
To monitor changes in the Lake's fish fauna, the Fishery Principles class at
California State University, Sacramento, conducted a fall population inventory
of Lake Greenhaven from 1974 through 1978, using the following types of
sampling gear: a 30.5-m (100-ft) X 1.8-m (6-ft) bag seine with 2.5-cm (1.0-
inch) mesh wings and a 1.3-cm (0.5-inch) mesh bag; a 12.2-m (40-ft) X 1.8-m
(6-ft) bag seine with 1.3-cm (0.5-inch) mesh; a 7.6-m (25-ft) X 1.8-m (6-ft)
bag seine with 3-mm (0.1-inch) bobbinet mesh; 1.8-m (6-ft) X .8-m (2. 6-ft)
fyke nets with 19-mm (0.75-inch) mesh; multifilament nylon experimental gill
nets, 45.6-m (150-ft) X 1.8-m (6-ft), with mesh sizes (square measure) of 19,
25, 38, 50, and 76 mm (0.75, 1 .0, 1 .5, 2.0, and 3.0 inches) . Additional collections
were made in May, June, and July 1978. Comparisons were made with fish
collections from Aceituno and Vanicek's (1976) study which were taken from
March 1 973 through January 1 974 and which utilized the same types of sampling
gear.
All fish were measured to the nearest millimetre, fork length (fl). Scale
analysis techniques for age and growth determination described by Aceituno
and Vanicek (1976) were used in this study.
SPECIES COMPOSITION AND RELATIVE ABUNDANCE
Eight species of fish were collected in Lake Greenhaven in 1 978: golden shiner,
mosquitofish, largemouth bass, bluegill, white crappie, Sacramento perch, white
catfish, and channel catfish. White catfish were not collected in 1973, while carp
and goldfish, both collected in 1973, were not taken in 1978.
In 1 973 Sacramento perch dominated the species complex, as they comprised
96% of the total catch from all sampling methods combined. In 1978, however,
they comprised only 2% of the total catch. In contrast, bluegill increased from
less than 3% of the total catch in 1973 to 94% in 1978. To make more specific
comparison of changes in abundance of the species between the 2 years, I
contrasted the average number of fish by species caught per overnight gill net
set of the 1 1 sets made in 1 973 with the 9 sets in 1 978 (Table 1 ) . The most striking
contrast was the decrease of the Sacramento perch from an average of 53.0 fish
per set in 1973 to only 10.9 in 1978. For the same years, bluegill increased from
0.7 fish per set to 6.8 fish. White catfish, golden shiner, and white crappie
showed slight increases. During the 1974-1977 period, when gill net collections
were made only in September or October, the Sacramento perch decline was
indicated by the abrupt drop in catch per set from 99.0 fish in 1975 to 17.0 and
7.3 fish in 1976 and 1977, respectively. Comparisons of catches with fyke nets
and seines were limited since the shoreline areas where these nets were used
have been altered, and the nets, especially the fyke nets, could not be used
180 CALIFORNIA FISH AND GAME
effectively after 1976. September fyke net catches of Sacramento perch dropped
from an average of 11 and 13 fish per net in 1973 and 1974, respectively, to 7
fish per net in 1975 and again in 1976. The 1975 figure may be misleading since
several of the fyke nets had been disturbed by intruders. Small bluegills (age 0
and I) dominated minnow seine collections in 1975, 1977, and 1978, whereas
young Sacramento perch were the most abundant fish in the 1973, 1974, and
1976 collections.
TABLE 1. Average Number of Fish Caught per Overnight Gill Net Set, 1973 and 1978, Lake
Greenhaven.
A verage no. fish
per set
Species 1973 (11 sets) 1978 (9 sets)
Sacramento perch 53.0 10.9
Bluegill 0.7 6.8
Largemouth bass 0.7 0.6
White crappie 0.0 1.3
Golden shiner 0.1 0.3
White catfish 0.0 0.4
SACRAMENTO PERCH POPULATION CHANGES
The size and age structure of the Sacramento perch population has changed
radically since 1973. Length-frequency histograms (Figure 1 ), based on all fish
collected during fall collections from 1973-1978, indicated a constant reduction
in range of sizes, with the disappearance of large and small fish. In 1973 perch
in the samples ranged from 35 to 265 mm PL, while in 1978 the size range was
reduced to 130 to 155 mm fl. There had also been a loss of younger age groups
due to reproductive failure in 1975, 1977, and 1978. Although successful repro-
duction did occur in 1976, no survivors of this year class were collected in 1977
or 1978. Mean size of these young-of-the-year perch in September 1976 was
considerably smaller than at this time in 1973 and 1974 (Figure 1 ).
Scale analysis of fish collected in 1978 revealed three age groups: IV, V, VI.
In contrast, in 1973 seven age groups (0 through VI) were present. Growth
histories of 1978 fish were not back-calculated because I had difficulty in estab-
lishing a body-scale relationship; however, mean lengths at time of capture were
much shorter in 1978 than the respective age group from 1973 (Table 2). I
conclude that the annual growth of the Sacramento perch has been dramatically
reduced over the past 4 years (Figure 1 ).
TABLE 2. Comparisons of Mean Fork Length (Millimetres) at Time of Capture of Sacra-
mento Perch by Age Group, 1973 and 1978, Lake Greenhaven (Number of Fish in
Parentheses).
Year of capture
Age 1973 ' 1978
IV 241 (17) 145 (20)
V 305 (1 ) 151 (9)
VI 319 (1) 164 (3)
* Data from Aceituno and Vanicek (1976)
Condition factors, Kfl ( = W3/L X 10^), were calculated for fish collected in
fall surveys (September or early October) from 1973 through 1978 (Table 3).
LAKE GREENHAVEN SACRAMENTO PERCH
181
The mean Kfl value dropped considerably from 1973 to 1974, and has remained
below 2.00 since. Throughout 1973, the mean K values never fell below 2.00
(Aceituno and Vanicek 1976). The difference between the mean K values from
1973 and subsequent years is significant at the 99% level.
-2
o
u
o
O
111
CO
20 40 60 80 100 120 140 160 180 200 220 240 260
FIGURE 1. Length frequencies of all Sacramento perch captured in September-October, 1973
through 1978, in Lake Greenhaven.
DISCUSSION AND CONCLUSIONS
The Lake Greenhaven Sacramento perch population is stressed and declining,
as evidenced by the reproductive failures, reduced growth, and low condition
coefficients in recent years, and by decreased relative abundance. Concurrently
the bluegill population has increased and is now the domimant species in the
Lake. Catch per unit effort statistics are not valid for comparing relative abun-
182 CALIFORNIA FISH AND GAME
dance of different species due to differences in vulnerability to gear, but the
major changes in catch per gill net set for bluegill and Sacramento perch un-
doubtedly do reflect changes in abundance over the 5-year period. Moreover,
the catches in the minnow seine hauls reflect this trend as no Sacramento perch
young-of-the-year were collected in 3 of the last 4 years when young bluegill
dominated the catches.
TABLE 3. Mean Condition Factors of Sacramento Perch Collected in Lake Greenhaven,
September-October, 1973-1978.
Mean K factor
(number of fish
Date of collection in parentheses)
3I2M73 2.40 (22)
9/21/74 1.84 (43)
9/13/75 1.74 (38)
9/11/76 1.64 (52)
10/6/78 1.83 (18)
Competition with exotic centrarchids, especially the bluegill, has been sug-
gested as a major cause of the decline of the Sacramento perch in its native
waters (Moyle, Mathews, and Bonderson 1974; Aceitunoand Nicola 1976). The
mechanism of this competition may involve interference. Observations in
aquaria indicate that in interspecific encounters, bluegill consistently dominate
and displace Sacramento perch (Mary Bacon, California State University, Sacra-
mento, pers. commun.; Moyle et al. 1974). Although Imler, Weber, and Fyock
(1975) concluded that Sacramento perch can compete successfully with a
variety of species, bluegill were either scarce or absent in their study ponds in
Colorado. Murphy (1948) attributed decline of the Sacramento perch to its
failure to guard its eggs; however, more recent investigators have reported that
perch do defend their nests against potential egg predators (Mathews 1965,
Aceituno 1974).
While bluegill and Sacramento perch were both stocked in Lake Greenhaven
after it was renovated in 1966, it is not clear why bluegill did not become
abundant until 1975, the time when the Sacramento perch began to decline. By
this time the bluegill may have become abundant enough to interfere with the
perch by displacing them from preferred habitats and spawning sites.
No major changes in water quality that might be detrimental to the Sacra-
mento perch were noted between 1973 and 1978. Commercial fertilizer was not
added to the Lake after 1973, and subsequently, primary productivity has proba-
bly decreased, as the increase in water transparency suggests. However, this
decrease in productivity would be expected to affect all species. Perhaps the
reduced food supply intensified interspecific competition between the bluegill
and Sacramento perch. 1 feel that it is unlikely that the decrease in turbidity in
itself was responsible for the perch decline, since thriving populations have been
reported from Lake Almanor (Aceituno and Vanicek 1976), Pyramid Lake
(Johnson 1958), and Crowley Lake (E. P. Pister, Assoc. Fish. Biol. Calif. Dept.
Fish and Game, pers. commun.) where water clarity was high. The only other
apparent environmental change has been the shoreline alteration and creation
of new bays along the northwest shore, but the decline of the perch population
was in evidence in 1975, well before the alterations began in 1977.
LAKE GREENHAVEN SACRAMENTO PERCH 183
In summary, observations on these changes in the Lake Greenhaven fish fauna
support the hypothesis that Sacramento perch are negatively affected by intro-
duced centrarchids, particularly the bluegill. If the present trend continues, the
Sacramento perch will soon become extinct in Lake Greenhaven, one of the few
locations where this species has sustained a population in its native range.
ACKNOWLEDGMENTS
I wish to extend my appreciation to the following for assisting in this project:
Peter B. Moyle and Martin R. Brittan, for reviewing the manuscript; Gary Gross-
man, for collecting the 1977 data; the numerous California State University,
Sacramento students who assisted in the field collections; and the Lake Green-
haven Homeowner's Association for allowing us free access to the Lake.
REFERENCES
Aceituno, M. E. 1974. A study of the status and ecology of the Sacramento perch, Archoplites interruptus (Cirard),
in California. M.S. thesis, Calif. State Univ., Sacramento. 66 p.
Aceituno, M. E., and S. J. Nicola. 1976. Distribution and status of the Sacramento perch, Archoplites interruptus
(Cirard), in California. Calif. Fish Came, 62(4):246-254.
Aceituno, M. E., and C. D. Vanicek. 1976. Life history studies of the Sacramento perch, Archoplites interruptus
(Cirard), in California. Calif. Fish Game, 62(1):5-20.
Imler, R. L., D. T. Weber, and O. L. Fyock. 1975. Survival, reproduction, age, growth, and food habits of Sacramento
perch, Archoplites interruptus (Cirard), in Colorado. Am. Fish. Soc, Trans., 104(2);232-236.
lohnson, V. K. 1958. Lakes Pyramid, Walker, and Tahoe investigations: Life history of the Sacramento perch.
Nevada Dept. Fish Game Proj. Rep. D-J F-4-R. 7 p. (Mimeo).
Mathews, S. B. 1965. Reproductive behavior of the Sacramento perch. Copeia, 1965 (2):224-228.
Moyle, P. B., S. B. Mathews, and N. Bonderson. 1974. Feeding habits of the Sacramento perch, Archoplites
interruptus. Am. Fish Soc, Trans., 103(2):399-402.
Murphy, G. I. 1948. A contribution to the life history of the Sacramento perch (Archoplites interruptus) in Clear
Lake, Lake County, California. Calif. Fish Game, 34(3):93-100.
184 CALIFORNIA FISH AND GAME
NOTES
A POPULATION OF THE ENDANGERED SANTA CRUZ
LONG-TOED SALAMANDER, AMBYSTOMA
MACRODACTYLUM CROCEUM, FROM
MONTEREY COUNTY, CALIFORNIA
On 12 October 1973, we found a juvenile Santa Cruz long-toed salamander,
Ambystoma macrodactylum croceum, under a wooden box at the edge of an
agricultural field 3.2 km north of Moss Landing, Monterey County, California.
This was the first of numerous specimens found in the same general area under
debris and represented the discovery of a third breeding population of A. m.
croceum. Previous to the discovery of these specimens, A. M. croceum was
known to occur at only two localities, both in Santa Cruz County; one population
breeding at Valencia Lagoon near Aptos, and another at Ellicott Pond near
Watsonville (Russell and Anderson 1956; Anderson 1967).
In an attempt to discover the breeding pond of this new population of A. m.
croceum, we examined three wetlands located within 1 km of the original
discovery site (Figure 1). Initially, we concentrated our efforts on studying
wetland no. 2. In late October and early November, 1973, we placed drift fences
and can traps, constructed as described by Ruth and Tollestrup (1973), on all
sides of wetland no. 2. These traps were monitored daily through December
1973. From January through June 1974, we periodically examined each of the
three wetlands by walking the shorelines and searching for adult and juvenile
salamanders under logs, debris, and emergent vegetation. Throughout this peri-
od, we used dipnets to search for larval salamanders in each wetland. We found
A. m. croceum in all three wetlands.
Wetland no. 1, an area of about 3 ha, is on the south side of California State
Highway No. 1 near its junction with Struve Road. The wetland is surrounded
on three sides by a salt water marsh and on the fourth by agricultural land.
Willows, Salix sp., grow along the northern side of the wetland and emergent
vegetation grows throughout most of the wetland.
An abundance of larval A. m. croceum were found in wetland no. 1. Most
larval salamanders were found on the east end of the wetland in what appeared
to be a man-made ditch approximately 100 m long, 5 m wide, and 1 m deep
at its greatest depth. Many juvenile salamanders were found under logs and
debris around this wetland. Pacific treefrog tadpoles, Hyla regilla, and red-legged
frog tadpoles, Rana aurora, were common in the wetland.
Wetland no. 2, covering an area of about 8 ha, is a pond on the north side
of California State FHighway No. 1 approximately 100 m NE of wetland No. 1.
Willows are scattered around the wetland but are most concentrated at the east
and west ends. Cattail, Typha sp., and bulrush, Scirpus sp., form dense stands
in the northern half of the wetland. The wetland is surrounded on three sides
by agricultural land and on the fourth side by a salt water marsh.
Numerous migrating A. m. croceum were captured in can traps near willow
groves on the east and west ends as they entered wetland no. 2. Although
numerous mature A. m. croceum migrated into the pond, we captured only one
NOTES
185
Springfield
X
UJ
w
<
ORIGINAL SIGHTING
d.
N
r
■\KhoiI
MOSS
LANDING
Wetland
Habitat
r-
0
Kilonfieters
I
FjCURE 1 . Three wetlands in Monterey County, California, where Santa Cruz long-toed salamand-
ers, Ambystoma macrodactylum croceum, were discovered.
186 CALIFORNIA FISH AND CAME
larval salamander throughout the season. Possibly the dense growth of emergent
vegetation in the wetland prevented additional captures. Other amphibians
observed in the wetland were Pacific treefrogs, red-legged frogs, and one tiger
salamander, Ambystoma tigrinum californiense.
Wetland no. 3, a large wetland area of about 40 ha, is approximately 1 km
northwest of wetlands 1 and 2 and is almost completely surrounded by agricul-
tural land. Dense stands of cattail and bulrush cover much of the wetland.
Willows are scattered around the wetland and two small groves are present in
the northwest end of the wetland.
Many mature and juvenile A. m. croceum were found under debris and dead
emergent vegetation on the northwest end of wetland no. 3, near the end of
Springfield Road, throughout the spring and summer. The presence of adult
salamanders in the wetland during the summer indicates that many salamanders
did not migrate into a separate terrestrial habitat after the breeding season.
Although many transformed salamanders were found under vegetation, we were
unable to capture any larval salamanders. Pacific treefrogs were the only other
amphibians seen in the immediate area.
It seems probable that the Santa Cruz long-toed salamanders occurring in
wetlands nos. 1 , 2, and 3 represent what remains of a formerly larger population.
The lack of native terrestrial habitat in the vicinity of the three wetlands is
presumably a major factor limiting the population size of A. m. croceum in the
area. It appears that the most suitable habitat is now restricted to the wetlands
themselves and many salamanders may not migrate into separate upland habitat.
Additional research is needed to evaluate the relative importance of the three
wetlands to A. m. croceum. In addition, the area in the vicinity of Elkhorn Slough
should be examined for additional breeding ponds and to determine if the
uplands around the slough serve as terrestrial habitat for A. M. croceum.
ACKNOWLEDGMENTS
We thank Stephen Ruth and Michael Johnson for their advice. The California
Department of Fish and Game supplied the materials used to construct drift
fences.
REFERENCES
Anderson, ). D. 1967. A comparison of the life histories of coastal and montane populations of Ambystoma
macrodactylum in California. Amer. Midi. Natur., 77(2): 323-355.
Russell, R. W., and ). D. Anderson. 1956. A disjunct population of the long-nosed (sic) salamander from the coast
of California. Herpetologica, 12; 137-140.
Ruth, S. B., and K. Tollestrup. 1973. Aspects of the life history and current status of the Santa Cruz long-toed
salamander (Ambystoma macrodactylum croceum) at Valencia Lagoon, Santa Cruz County, California.
Report for California Division of Highways. 54 pp.
—Larry G. Talent and Carline L Talent, Department of Fisheries and Wildlife,
Oregon State University, Corvallis, Oregon 97331. Accepted for publication
January 1980.
REPEAT SPAWNING OF PACIFIC LAMPREY
Accounts of the life history of Pacific lampreys, Entosphenus tridentatus, state
that adults die after spawning (Hart 1973, Scott and Crossman 1973). The
appearance of kelt lampreys at the Snow Creek and Salmon Creek downstream
NOTES 187
migrant traps led to the marking of these fish and the subsequent recapture of
two of them.
The Washington Department of Game operates permanent fish traps near the
mouths of Snow and Salmon creeks. The creeks are located on the northeastern
corner of the Olympic Peninsula and drain into the Strait of Juan de Fuca. The
traps operate year around and trap upstream and downstream migrants. Lam-
prey kelts captured in the traps are measured to the nearest millimeter total
length (tl) and marked by cutting a notch in the dorsal fin. All lampreys are
subsequently examined for marks.
During the springs of 1978 and 1979, eight lamprey kelts between 291 and 451
mm TL were marked in Salmon Creek. Most of the kelts were in good condition;
they swam strongly and did not appear to be debilitated. On 5 March and 25
October 1979, two marked lampreys measuring 575 mm and 470 mm tl, respec-
tively, were captured in the upstream migrant trap in Salmon Creek. A more
detailed and extensive study will be needed to determine the extent of the ability
of lampreys to spawn more than once and what effect this has on their popula-
tion dynamics.
REFERENCES
Hart, ). L. 1973. Pacific fishes of Canada. Fish. Res. Bd. Can. BulL, (180): 1-740.
Scott, W. B., and E. J. Grossman. 1973. Freshwater fishes of Canada. Fish. Res. Bd. Can. Bull., (184): 1-966.
—John H. Michael Jr., Washington Department of Came, Snow Creek Station,
Star Route 2, Box 513, Port Townsend, Washington 98368. Accepted for
publication December 1979.
A DIVER-OPERATED SNAGGING DEVICE FOR
CAPTURING LINGCOD, OPHIODON ELONGATUS
During field operations to obtain lingcod for a tagging study, diving observa-
tions revealed that large numbers of lingcod were present in a given area but
few were being taken by hook-and-line. Also, it was found that lingcod, either
in the open or concealed in caves, could be approached closely by divers
without being frightened away. Based on this knowledge and in order to improve
the catch-per-unit-of-effort of this species, a diver-operated snagging device
(Figure 1) was invented by Reinhold Banek (Fish and Wildlife Seasonal Aid,
Department of Fish and Game, Monterey, California), which causes little injury
to the fish.
One part of the device consists of a hollow, fiberglass fishing pole, about
2.5-cm of which was cut off from the tip. The outside diameter of the pole's butt
is 2.5 cm and that of the cut-off tip is 0.6 cm. The pole has one eyelet about 10
cm from its tip and another just above the handle. A female electrical fitting was
placed inside the tip end of the pole and bonded with epoxy.
The other part of the device consists of a 10.2-cm long, 0.3-cm diameter metal
shaft, onto one end of which was bonded a male electrical fitting, and onto the
other end was soldered a 12/0 double fish hook with barbs removed. One end
of a 90-cm long stainless steel wire was looped through the eye of the hook and
fastened to itself with a crimp-type cable clamp. The other end of the wire was
threaded through the upper eyelet of the pole and attached by a ring and snap
to a 30.5-cm long, 9.5-mm diameter piece of surgical tubing, which was threaded
through the lower eyelet and secured to the handle of the pole.
188
CALIFORNIA FISH AND CAME
12/0 DOUBLE HOOK
3.2 mm FEMALE FITTING
3.2 mm MALE FITTING
HOLLOW SHAFT
METAL SHAFT
CORK
HANDLE
SURGICAL TUBING
STAINLESS STEEL WIRE
137 cm TOTAL LENGTH
FICURE 1. Snagging device used to capture lingcod, Ophiodon elongatus.
By inserting the male shaft fitting into the female pole fitting, hooks pointed
upward, the snagging device was ready to use. When a lingcod was located, the
diver would position the hooks under the lower jaw of the fish. A quick jerk
backward would both set the hook in the jaw and release it from the end of the
pole. The fish was then played, much like one would be with hook-and-line. The
surgical tubing maintained tension on the line but provided sufficient elasticity
to minimize injury to the fish. Only one lingcod sustained a major injury from
the device; the fish was inadvertently hooked posteriorly to the lower jaw, in
the gill region, causing excessive bleeding.
When snagged, a fish would fight furiously for 1 0-1 5 s, then sink to the bottom,
usually with mouth agape. A second diver would quickly bag it and remove the
hook before the fish recovered and began to fight again. The fish was then taken
to the surface, tagged, and released.
During 200 d of hook-and-line fishing for lingcod in the Hopkins Marine Life
Refuge kelp beds, the catch-per-day (c/d) was 0.32. Using the device, 45 fish
were captured in 3 d for a c/d of 15.0. At Chase Reef, in open water, hook-and-
line c/d was 0.82 compared to 6.0 for the snagging device. The highest c/d for
the device was 24, and lingcod in this group ranged in size from 400 mm to 900
mm total length.
The "snagger" is an inexpensive device that can be used on other demersal
fishes such as cabezon, Scorpaenichthys marmoratus, and kelp greenling, Hexa-
grammos decagrammus. By altering hook size, it may be possible to use the
device on many other fishes.
—James L. Houk, Operations Research Branch, California Department of Fish
and Game, 2201 Garden Road, Monterey, California 93940. Present address:
Marine Culture Laboratory, California Department of Fish and Game, Granite
Canyon, Coast Route, Monterey, California 93940. This study was performed
as part of Dingell-Johnson project F-25-R (Central California Marine Sport fish
Survey), supported by Federal Aid in Fish Restoration funds. Accepted for
publication October 1979.
NOTES 1 89
KARYOTYPE OF THE SACRAMENTO PERCH,
ARCHOPLITES INTERRUPTUS
INTRODUCTION
The family Centrarchidae contains 30 species of sunfishes and basses, grouped
into nine genera. Karyotypic information is presently available for 23 centrarchid
species representing eight genera (Chiarelli and Capanna 1973; Cold, Karel, and
Strand 1979). The genus yet to be examined, Archoplites, contains a single
species, the Sacramento perch, A. interruptus. This species was once common
in Clear Lake (Lake County), and in the Pajaro-Salinas and the Sacramento-San
Joaquin drainage systems, but habitat destruction and egg predation and compe-
tition by introduced fishes have made it rare in its original range. It has, however,
been introduced into several lakes in California outside the original range, and
into other states ( Moyle 1 976) . The Sacramento perch is the only extant centrar-
chid native to waters west of the Rocky Mountains. Avise, Straney, and Smith
(1977) pointed out that since centrarchids are lowland forms, Archoplites has
likely been isolated from the other centrarchids since the time of formation of
the Rockies in the Miocene or early Pliocene. This study was undertaken to
determine if the Sacramento perch has diverged karyotypically from the other
centrarchids.
METHODS AND MATERIALS
Five Sacramento perch collected in California were processed for chromoso-
mal analysis, one from Upper Ruth Lake, Merced County, and four from Lake
Greenhaven, Sacramento County. Chromosome preparations were made using
either the leucocyte culture method of Thorgaard (1976) or the solid tissue
method of Kligerman and Bloom (1977). Both pokeweed and phytohemaglutti-
nin were used as mitogens in leucocyte cultures, but only phytohemagluttinin
gave satisfactory results. Only well spread cells, in which chromosomes could
be counted unambiguously, were scored.
RESULTS AND DISCUSSION
Acceptable chromosome spreads were obtained from three fish. The modal
chromosome number for all three fish was 48 (Table 1 ) . Of the 85 cells scored,
61 (72%) were modal, 17 (20%) were hypomodal, and 7 (8%) were hypermo-
dal. The high percentage of hypomodal counts was due primarily to chromo-
some loss in the poor quality spreads of fish #4. The modal karyotype (Figure
1 ) is characterized by a single pair of subtelocentric chromosomes (the first pair
shown) and 23 pairs of acrocentric chromosomes. Using the criterion that only
metacentric and submetacentric chromosomes be counted as biarmed, the
chromosome arm number of the fish sampled was 48. No sexual dimorphism
in karyotype was seen; none has been reported in centrarchids.
Two basic centrarchid karyotypes have been reported. Most species have 48
chromosomes with 48 arms, a karyotype found in many diverse groups of fish
(Ohno 1974). The orange-spotted sunfish, Lepomis humilis, and all black bass
(Micropterus) species examined, however, differ from the common karyotype
by a single centric fusion, and have 46 chromosomes with 48 arms (Roberts
1964; Post 1965; Thompson, Hubbs, and Edwards 1978). The green sunfish,
Lepomis cyanellus, is polymorphic for the two karyotypes ( Roberts 1 964; Begak,
190
CALIFORNIA FISH AND CAME
TABLE 1.
Chromosome Counts of Cells of Three Sacramento Perch. Numbers in Paren-
theses Indicate How Many of the Counts were Obtained by Doubling Bivalent
Counts in Meiosis I Prophase Spreads.
Counts
Fish # Sex Tissues sampled <44
1 F Leucocytes 1
3 M Testes
4 M Kidney, gill, testes 2
Total 3
45
46
47
48
49
50
1
1
1
22
1
1
2
11(9)
1
2(2)
2
3(1)
2
28(11)
1
2(2)
5
4
5
61
3
4
FIGLIRE 1. Metaphase chromosomes of a female Sacramento perch, Archoplites interruptus:
2n =48, 48 arms.
Begak, and Ohno 1966). Fontana, Chiarelli, and Rossi (1970) reported a karyo-
type of 46 chromosomes with 56 arms for the pumpkinseed sunfish, Lepomis
gibbosus, a species previously reported to exhibit the common karyotype (Rob-
erts 1964). The Sacramento perch, with 48 single-armed chromosomes, is a
chromosomally typical centrarchid.
ACKNOWLEDGMENTS
We wish to thank John Dentler for providing the specimens and Dr. Graham
Gall for the use of his lab facilities. This study was supported by a U. S. Public
Health Service postdoctoral fellowship to G. H. T. (1-F32-GMO6298-01 ).
REFERENCES
Avise,J.C., D. O. Straney, and M. H.Smith. 1977. Biochemical genetics of sunfish. IV. Relationships of centrarchid
genera. Copeia, 1977(2): 250-258.
Be^ak, W., M. L. Begak, and S. Ohno. 1966. Intraindividual chromosomal polymorphism in green sunfish (Lepomis
cyanellus) as evidence of somatic segregation. Cytogenetics, 5(5): 313-320.
Chiarelli, A. B., and E. Capanna. 1973. Checklist of fish chromosomes. Pages 206-232 in A. B. Chiarelli and E.
Capanna, eds., Cytotaxonomy and vertebrate evolution. Academic Press, New York.
NOTES 191
Fontana, F., A. B. Chiarelli, and A. C. Rossi. 1970. II cariotipo di alcune specie di Cyprinidae, Centrarchidae,
Characidae studiate mediante colture "in vitro". Caryologica, 23(4): 549-5&4.
Cold, ). R., W. ]. Karel, and M. R. Strand. 1980. Chromosome formulae of North American fishes. Prog. Fish-Cult.
42(1);10-23.
Kligerman, A. D., and S. E. Bloom. 1977. Rapid chromosome preparations from solid tissues of fishes. Can., Fish.
Res. Bd., J., 34(2): 266-269.
Moyle, P. B. 1976. Inland fishes of California. Univ. of Calif. Press, Berkeley and Los Angeles, CA 405 pp.
Ohno, S. 1974. Protochordata, Cyclostomata, and Pisces. Pages 1-91 in B. John, ed.. Animal cytogenetics, Vol.
4, Chordata 1. Borntraeger, Berlin.
Post, A. 1965. Vergleichenede Untersuchungen der Chromosomenzahlen bei Susswasser-Teleosteern. Z. Zool.
Syst. Evolforsch., 3(1/2): 47-93.
Roberts, F. L. 1964. A chromosome study of twenty species of Centrarchidae. J. Morphol., 115(3): 401-418.
Thompson, K. W., C. Hubbs, and R. ). Edwards. 1978. Comparative chromosome morphology of the black basses.
Copeia, 1978(1): 172-175.
Thorgaard, G. H. 1976. Robertsonian polymorphism and constitutive heterochromatin distribution in chromosomes
of the rainbow trout (Salmo gairdneri). Cytogenet. Cell Genet. 17(4): 174-184.
Craig A. Busack and Gary H. Thorgaard, Department of Animal Science, Univer-
sity of California, Davis, CA 95616. Mr Thorgaard' s current address is: Pro-
gram in Genetics, Washington State University, Pullman, WA 99164. Accepted
for publication December 1979.
192 CALIFORNIA FISH AND CAME
BOOK REVIEWS
Marine Life
By David and Jennifer George; Published in the USA by Wiley-lnterscience, a Division of John Wiley and
Sons, Inc., New York; 1979; 288 pp; $39.95.
One of the most valuable contributions of this richly illustrated encyclopedia of marine invertebrates
is that it contains the most recent survey of their classification by taxonomists. Since it was written
and researched by two biologists from Creat Britain, the classification scheme probably represents
more of a European view than a North American view. For example, the marine members of Phylum
ARTHROPODA, crustaceans, etc., have been separated out and divided into three new phyla:
Crustacea, Chelicerata (horseshoe crabs, sea spiders) and Uniramia (no truly marine representa-
tives). Twenty-seven phyla are covered, the description includes a schematic breakdown of each
phylum into classes, superorders, orders, suborders, and infraorders. The narrative contains a brief
description of the life history of the animals within each group and representative species are
discussed in terms of general description of the animal, habitat and known geographic range,
maximum size, and, in some cases, additional life history data is given. The selection of the 1,300
illustrated species is biased toward the Atlantic-Mediterranean-Caribbean area and the Indo-Pacific
area.
A cursory sample of Phyla PORIFERA, CNIDARIA, and CRUSTACEA yielded 53%, 44%, and 50%
of the species, respectively, from the Atlantic area and 29%, 41%, and 17% of the species, respec-
tively, from the Indo-Pacific area. Northeastern Pacific species are poorly represented. Thus, the
authors' statement in the Introduction . . . "text and colour photographs of the living marine
animals in their natural environment, which should enable readers to identify And classify the marine
invertebrates that they see" . . . would certainly not hold true for the Pacific coast area.
Another small problem arises for the information given for the illustrated species — it appears that
some of this information may be misleading. For example, the range of the common California
subtidal snail, Calliostoma ligatum's is given as occurring in the northeast Atlantic; their occurrence
in the northeast Pacific is not mentioned.
The photos are very good, ranging from fair to excellent, and add greatly to the overall presenta-
tion. I recommend this book to those marine biologists interested in the most recent marine inverte-
brate classification. Amateur naturalists and divers will find the book helpful in classifying at least
some of the invertebrates they may observe. — Daniel W. Cotshall
Big Game of North America — Ecology and Management
Edited by John L. Schmidt and Douglas L. Gilbert for Wildlife Management Institute; Stackpole Books,
Harrisburg, PA. 1978; 490 pp; illustrated; $17.95.
Big Came of North America is an easy to read collection of 27 chapters and 2 appendices dealing
with the animals, their management in the past, present, and future. The first chapter presents the
general evaluation and taxonomic key to North America big game. The next 1 5 chapters are devoted
to individual species or species groups, including exotics. Each of these chapters has a more or less
standard format that includes: taxonomy, population dynamics, ecology, management, and future
considerations for a species or group. The remaining chapters present management considerations,
including behavior, modeling, carrying capacity, predator control, and sociological considerations
in management and in the future.
All chapters are not equally well done, but as a text for students of big game management or as
a reference for managers will be a valuable asset. 1 enjoyed the book and, as California's Big Game
Coordinator, have encouraged its use by our big game biologists. — Brian Hunter
Tuna and Billfish — Fish Without a Country
By James Joseph, Witec Klawe, and Pat Murphy; paintings by George Mottson. Inter-American Tropical
Tuna Commission, P.O. Box 1529, La Jolla, CA; 1979; VII -\- 46 pp; illustrated; $7.95.
Tuna, billfish, and their close relatives are among the most fascinating and sought after creatures
inhabiting the world's oceans, but well grounded, popular accounts of their life have been rare. This
book admirably fills that gap, presenting, in 18 pages, a capsule of information on the birth, growth,
adaptation, migration, fishery, and conservation of the tunas and billfish. Most of the remainder of
the book is devoted to 12 of George Mattson's superb watercolors of tuna and billfish, alone worth
the purchase price, and five maps detailing present knowledge of the distribution, migration, and
spawning areas of albacore, bluefin tuna, skipjack tuna, yellowfin tuna, and striped marlin. A
summary of International Game Fish Association world record catches of tuna, billfish, and related
species completes the book. — Robson A. Collins
PhotoelectTonic composition by
80510 — 800 3-80 4,500 LDA caupornu omcE of state printing
I Si
- ii
2 -J
-I :?
o
CO
u> a
tn
0) en
- »*
^ a>
4 so CS
' -c *»
! 3» rti
iiS
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11