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TAXONOMY AND DISTRIBUTION OF THE BULL TROUT 169

Sympatry

Sympatry of 5. ma/ma and 5. confluentus occurs in the Puget Sound of Wash-
ington, the Skeena Basin of British Columbia, and the Taku Basin of southern
Alaska and northern British Columbia. Information available at this time on
Livingston Stone's incompletely cataloged USNM specimens indicates that sym-
patry between S. ma/ma and 5. confluentus may also have occurred in the
Sacramento basin of California. Both S. ma/ma and 5. con fluentus were identified
from the Yukon Basin; however, S. ma/ma came from the Tanana drainage of
central Alaska and 5. confluentus from the extreme headwaters in British Co-
lumbia, Canada. A complete understanding of how S. confluentus and S. malma
maintain sympatry will probably come from a study of these species in the
Skeena Basin of British Columbia. Both appear to be disseminated throughout
these waters, where considerable study of the "Dolly Varden" has already taken
place.

In the Skeena drainage (Figure 1, insert), specimens of S. confluentus were
studied from the following lakes: Lakelse, Damschilgwit (Cabin), Morrison,
Morice, Slamgeesh, Bear, and Sustut. Specimens of S. malma came from Johan-
son and Alastair lakes. Two suspected hybrids came from Swan and Morrison
lakes. Although the hybrids indicate both species probably occur in some lakes,
it is possible that certain of the lakes may contain only one of the species pair.
Larger samples from these lakes may be helpful in determining to what extent
hybridization is taking place. In the taku River, S. malma was taken 22 km (14
miles) upstream from the mouth at Canyon Island where Meehan and Siniff
(1962) reported downstream migration of juvenile Dolly Varden in 1961. 5.
confluentus was taken further inland in Flannigan Slough, a small tributary to the
Taku River. The Taku River collections suggest that S. malma and S. confluentus
may be ecologically separated, with anadromous S. malma occupying most of
the lower drainage, especially Twin Lakes, the lower main channel, and the river
mouth, and S. confluentus restricted to certain small tributaries, such as Flanni-
gan Slough and perhaps the headwaters.

Of nine specimens examined from Puget Sound, five were S. malma taken
near Port Townsend, Washington in 1884. Labeling, as well as their silvery
pigmentation, indicated they were sea run individuals. The other four specimens
are S. confluentus. Two of these were taken by D. S. Jordan in 1880, and labeled
"Puget Sound." The third was taken in Elliot Bay at Seattle in 1 889 and the fourth
was captured in a freshwater tributary to Puget Sound near Ft. Steilacoom in
1856. Jordan's specimens are two of ten sent to the United States National
Museum and may have been collected during his work on the fishes of Puget
Sound (Jordan and Starks 1895).

S. confluentus appears to be distributed throughout the MacKenzie basin in
British Columbia and Alberta. Unfortunately, no material was available from the
Nahanni River, part of the Liard drainage in the Northwest Territories, and only
one specimen of S. malma was found in samples from the MacKenzie (USNM
147661).

McPhail (1961 ) demonstrated the existence of northern and southern forms
of 5. malma in North America. The northern form occurs in the coastal drainages
of the Bering Sea north to Seward Peninsula. Specimens corresponding to the
northern form have been examined for this study from the Yukon basin of central
Alaska. These specimens also resemble the S. malma-Wke char described as



170 CALIFORNIA FISH AND CAME

Salvelinus anaktuvukensisby Morrow (1973) from the north slope of the Brooks
Range, Alaska. Data from these Salvelinus were not used in making comparisons
with S. confluentus. McPhail (1961 ) stated that head size would not distinguish
the form which Jordan, Evermann, and Clark (1930) called Salvelinus malma
spectabilis. However, if McPhail's data (1961 ) on head size are reexamined in
light of the present work, it can be seen that the samples shown to have the
longest heads (Cottonwood River, Sage Creek, Glacier National Park, and prob-
ably also Bowser Lake in the Nass drainage) are from localities where S. con-
fluentus is found. Except for the Taku River, where S. confluentus and S. malma
may have been present in a mixed sample, the other samples represent S. malma
and show an average smaller head size. Much of McPhail's material was reex-
amined for this study. The samples of S. confluentus from the Taku River drain-
age were found to be smaller-headed with respect to samples of 5. confluentus
from other localities, including the adjacent Yukon basin. Taku River basin 5.
confluentus live at the extreme end of the northern dispersal route. Transfer to
this basin probably took place from the Liard via the Yukon headwaters or
directly from the western reaches of the Liard.

Variability

At the end of the southern dispersal route in the Sacramento basin, the
McCloud River S. confluentus possess the largest head size and are also distin-
guished in having a greater percentage of individuals (50% of those examined)
lacking basibranchial teeth. Only one specimen outside of the McCloud River
was found to lack basibranchial teeth. Jordan ( 1 879 ) at one time recognized the
McCloud River population as a separate species, {Salvelinus bairdif), on the
basis of this character.

Two specimens collected sometime prior to 1877 are part of Livingston Sto-
ne's material sent to the USNM, most of which came from the McCloud River
or Sacramento River drainage. Small head size identifies them as S. malma. In
other characters, such as number of gill rakers, compressed body, straight maxil-
la and supraethmoid, they resemble S. malma. Silver pigment on their sides
indicated they may have been anadromous individuals. In the shape of their gill
rakers and head form they are not typical of 5. malma but the deteriorated
condition of these specimens prevented further study.

Of the coastal collections, S. malma from Puget Sound, Washington and the
Soleduck River of Washington's Olympic Peninsula are geographically closest
to the McCloud River specimens. Those taken from Puget Sound in the 1880's
were anadromous and compared closely with S. malma from further north along
the coast of British Columbia. The Soleduck River specimens represent a popula-
tion isolated above a high falls. The largest individual measured 135 mm. They
differed from anadromous S. malma in their larger heads and fewer vertebrae
and gill rakers. It appears likely that prior to 1900, S. malma ranged south along
the Pacific Coast to California and may have been fairly common in Washing-
ton's coastal waters of Puget Sound (Jordan and Starks 1895; Dymond 1942).

Specialization

Radiographs of 1 12 5. confluentus showed about 13% with whole fish in their
stomachs. Sculpins predominated in the stomach contents, but at least two bull
trout had eaten salmonids. Fewer S. malma had fish in their stomachs. Some S.



TAXONOMY AND DISTRIBUTION OF THE BULL TROUT 171

malma had eaten gastropods, a food also seen in the stomachs of three S.
confluentus. One 380 mm S. confluentus examined from the Finlay River near
Ft. Grahame, British Columbia (NMC 66-437), had swallowed a 21 5 mm individ-
ual of its own species. Two bull trout from northern British Columbia had eaten
small mammals (one a shrew and the other an unidentified rodent).

Fish eating habits of the bull trout have been noted by Ricker (1941 ), Godfrey
(1955), Jeppson and Platts (1959), Bjornn (1961), and Thompson and Tufts
(1967). Armstrong and Morton (1969) summarized other food habit studies of
the bull trout. Scott and Crossman (1973) have recently reviewed the food
habits of the bull trout under their section on the Dolly Varden. According to
Brown (1971 ), the principal food of the adult bull trout is fish, although it will
utilize other vertebrates of suitable size, such as frogs, snakes, mice, and duck-
lings.

Characters of the jaws, teeth, and head of S. confluentus which differ from
those of S. malma are best explained as adaptions to a piscivorous habit. The
large area for jaw muscle insertion, large jaws and teeth, the curved maxilla, the
elongate hyoid bar with numerous branchiostegal rays, the high number of
mandibular sensory pores, and the elongated head of the supraethmoid for
articulation of the extended premaxillary ascending processes, are features par-
alleled in the lake trout, S. namaycush, a species well-known for its piscivorous
diet.

The direction of evolution in S. confluentus has been away from a diverse
predator, such as anadromous S. malma toward a more specialized fish-eating
mode of existence entirely in fresh water. The changes in the head and compo-
nent bones are the easiest to document, but there are probably marked behav-
ioral and ecological differences between 5. confluentus and S. malma that have
not yet been studied. Most of the similarities pointed out above between the bull
trout and the lake trout are considered as parallel developments and are not
considered to be evidence of a close phyletic relationship.

SUMMARY AND CONCLUSIONS

The bull trout was first described as Salmo spectabilis in 1856 by Girard from
a specimen collected at The Dalles, Oregon, on the lower Columbia River.
Girard's specific name "spectabilis" does not stand because of the rules of
zoological nomenclature pertaining to homonyms. The name campbelli was
substituted by Suckley, who described the bull trout three more times under the
names "confluentus", "bairdii", and " parkei." In 1882 Jordan and Gilbert
included the above names except confluentus in the synonymy of 5. malma,
where they have remained to the present. With formal species recognition for
the bull trout, its scientific name becomes Salvelinus confluentus (Suckley); the
common name, Dolly Varden, applies to Salvelinus malma (Walbaum).

Evidence for specific distinction of the bull trout is found in a series of osteo-
logical, morphometric, and meristic characters that remain relatively constant
throughout its distributional range including areas of sympatry with S. malma.
The size and shape of the head and jaws, head length, the number of branchi-
ostegal rays, and the morphology of the gill rakers are the easiest characters to
use in separating the bull trout from S. malma. The shape of the supraethmoid
bone is also highly diagnostic for the bull trout, but it must be exposed through
removal of overlying tissue. The shape of the neurocranium and hyomandibular



172 CALIFORNIA FISH AND GAME

are also distinctive. Additional osteological characters are found in the maxilla,
premaxilla, ceratohyal, opercle, and frontal bones.

The cranial structures in the bull trout that differ from those of the Dolly
Varden are interpreted as modifications toward a more piscivorous existence in
freshwater. The changes are genetic and have occurred through the long process
of selection and adaption. By no means can they be construed as environmental-
ly-induced somatic changes.

The life history of the bull trout differs significantly from that of the Dolly
Varden in being almost completely nonanadromous throughout its known range.
Ecological and behavioral differences between the two have not been studied
in detail.

The bull trout is widely distributed in montane lake and stream habitats on
both sides of the Continental Divide between lat 50° and 60° N. It appears to have
an affinity for cold waters fed by mountain glaciers and snowfields. In the
deglaciated part of its range in western Canada, the bull trout has dispersed from
the Columbia River basin through headwater transfer and crossover following
the retreat of the Cordilleran ice sheet in Late Wisconsin time. The distribution
pattern to the south of the ice sheet may be older. Populations of bull trout in
the Sacramento, Klamath, and southern Snake River drainages all show signs of
depletion.

ACKNOWLEDGMENTS

I am deeply grateful to the staffs at the University of Michigan Museum of
Zoology, National Museum of Natural Sciences, Canada, and the United States
National Museum of Natural History, Smithsonian Institution, for their coopera-
tion.

Specimens examined in this study were made available by R. M. Bailey and
R. R. Miller (UMMZ); D. E. McAllister (NMC); E. A. Lachner and W. R. Taylor
(USNM); W. I. Follett, (CAS); R. J. Behnke, Colorado State University; C. M.
Barbour, (when at the) University of Utah; R. Wasem, U. S. National Park
Service; W. Seegrist, U. S. Forest Service. S. J. Nicola, California Department of
Fish and Game, provided information on the bull trout captured in 1975 from
the McCloud River. R. J. Behnke, R. R. Miller, R. M. Bailey, S. J. Nicola, and J.
E. Morrow critically read the manuscript. I wish to thank these individuals for
their considerable assistance.

I am particularly indebted to R. R. Miller who supported the early aspects of
this study between 1968 and 1970 through his National Science Foundation
Grant (GB-4854) on Cenozoic Fishes. This work is an outgrowth of previous
studies on fossil salmonids at the University of Michigan.

REFERENCES

Armstrong, R. H., and W. M. Morton. 1969. Revised annotated bibliography on the Dolly Varden char. Alaska Dep.

Fish Came Res. Rep. 7, 107 p.
Bailey, R. M., chairman. 1970. A list of common and scientific names of fishes from the United States and Canada,

3rd ed. Amer. Fish. Soc. Spec. Publ. 6, 150 p.
Bjornn, T. C. 1961 . Harvest, age structure and growth of game fish populations from Priest and Upper Priest lakes.

Amer. Fish. Soc, Trans., 90(1): 27-31.
Brown, C. J. D. 1971. Fishes of Montana. Montana State University, 207 p.
Campbell,). B. 1882. Notes on McCloud River, California and some of its fishes. U. S. Fish. Comm. Bull. 1, (1881):

44-46.
Cavender, T. M. 1969. An early Pliocene Salvelinus from Nevada with comparative notes on recent species.

Abstracts 49th Meet. Amer. Soc. Ichthy. Herpet., 1969: 29-30.



TAXONOMY AND DISTRIBUTION OF THE BULL TROUT 173

Cope, E. D. 1879. The fishes of Klamath Lake, Oregon. Amer. Natural., 13(12): 784-785.

Dymond, J. R. 1932. The trout and other game fishes of British Columbia. Canada Dep. Fish., Ottawa, 51 p.

. 1942. The occurrence of the Dolly Varden charr in salt water off British Columbia. Can. Field Natural.,

14(7): 110-112.

Evermann, B. W., and H. C. Bryant. 1919. California trout. Calif. Fish Game, 5(3): 105-135.

Cirard, C. F. 1856. Notice upon the species of the genus Salmo of authors, observed chiefly in Oregon and
California. Proc. Acad. Nat. Sci. Philadelphia, 8: 217-220.

1858. Fishes, pp. 1-400. /^general report on the zoology of the several Pacific Railroad routes. U. S. Pacific

Railroad Survey, 10(4).

Godfrey, H. 1955. On the ecology of the Skeena River whitefishes, Coregonus and Prosopium. Canada, Fish. Res.
Bd., )., 12(4): 499-542.

Hart, ). L. 1973. Pacific fishes of Canada. Canada, Fish. Res. Bd. Bull. 180, 740 p.

Hubbs, C. L., and R. R. Miller. 1948. The zoological evidence/correlation between fish distribution and hydro-
graphic history in the desert basins of western United States. In The Great Basin, with emphasis on Glacial
and Postglacial times. Bull. Univ. Utah, 38(20), Biol. Ser. 10: 17-166.

Jeppson, P. W„ and W. S. Platts. 1959. Ecology and control of the Columbia squawfish in northern Idaho lakes.
Amer. Fish. Soc, Trans., 88(3): 197-202.

Jordan, D. S. 1879. Notes on a collection of fishes from the Clackamas River, Oregon. Proc. U. S. Nat. Mus. 1878,
1 : 69-85.

1 907. The trout and salmon of the Pacific Coast. Rep. State Bd. Fish Comm. Calif., 1 905-1 906. Sacramento,



112 p.
1923. The name of the Dolly Varden trout, Salvelinus spectabilis (Girard). Copeia, 121: 85-86.



Jordan, D. S., and B. W. Evermann. 1896. The fishes of North and Middle America. U. S. Nat. Mus. Bull. 47, Pt.
1. 1,240 p.

Jordan, D. S., B. W. Evermann, and H. W. Clark. 1930. Checklist of the fishes and fish-like vertebrates of North
and Middle America, north of the northern boundary of Venezuela and Columbia. U. S. Comm. Fish, Rep.,
(1928): 1-670.

Jordan, D. S., and C. H. Gilbert. 1882. Synopsis of fishes of North America U. S. Nat. Mus. Bull. 16: 1,018 p.

Jordan, D. S., and E. A. McGregor. 1925. Family Salmonidae. In records of fishes obtained by David Starr Jordan

in Japan, 1922, by D. S. Jordan and C. L. Hubbs. Memoirs Carnegie Mus., 10(2): 93-346.
Jordan, D. S., and E. C. Starks. 1895. The fishes of Puget Sound. Contributions to biology from the Hopkins

Laboratory of Biology III, Leland Stanford Jr. Univ. Publ.,: 785-855.
Lindsey, C. C. 1964. Problems in zoogeography of the lake trout, Salvelinus namaycush. Canada, Fish. Res. Bd.,

J., 21(5): 979-994.
McPhail, ). D. 1961. A systematic study of the Salvelinus alpinus complex in North America. Canada, Fish. Res.

Bd., Jr., 18(5): 793-816.
McPhail, ). D., and C. C. Lindsey. 1970. Freshwater fishes of northwestern Canada and Alaska. Canada, Fish, Res.

Bd., Bull. 173, Ottawa, 381 p.
Meehan, W. R., and D. B. Siniff. 1962. A study of downstream migrations of anadromous fishes in the Taku River,

Alaska. Amer. Fish. Soc, Trans., 91 (4): 399^07.
Miller, R. R., and W. M. Morton. 1952. First record of the Dolly Varden Salvelinus ma/ma from Nevada. Copeia,

3: 207-208.

Morrow, J. E. 1973. A new species of Salvelinus from the Brooks Range, northern Alaska. Univ. Alaska Biol. Pap.
13: 1-8.

Morton, W. M. 1955. Charr or char — history of a common name for Salvelinus. Science, 121 (3155): 874-875.

1965. The taxonomic significance of the kype in American salmonids. Copeia, 1965 (1): 14-19.

1970. On the validity of all subspecific descriptions of North American Salvelinus ma/ma (Walbaum).

Copeia, 1970 (3): 581-587.

Morton, W. M., and R. R. Miller. 1954. Systematic position of the lake trout, Salvelinus namaycush. Copeia, 1954
(2): 116-124.

Paetz, M. J., and J. S. Nelson. 1970. The fishes of Alberta. Prov. of Alberta, Edmonton. 281 p.

Ricker, W. E. 1941. Consumption of young sockeye salmon by predaceous fish. Canada, Fish. Res. Bd., J., 5(3):
293-313.

Rostlund, E. 1951. Three early historical reports of North American freshwater fishes. Copeia, 1951 (4): 295-296.

Scott, W. B., and E. J. Crossman. 1973. Freshwater fishes of Canada. Canada, Fish. Res. Bd. Bull. 184, Ottawa, 966

P-
Shaposhnikova, G. K. 1971. Comparative morphological description of certain species of the genus Salvelinus

(Nilsson) Richardson. Tr. Zool. Inst. Leningrad, Acad. Sci. USSR, 48 : 4-29.



174 CALIFORNIA FISH AND CAME

Suckley, C. 1858. Descriptions of several new species of Salmonidae, from the North-West coast of America. Ann.
Lye. Nat. Hist., 7 : 1-10.

1860. Report upon Salmonidae, Chapter I. In Pacific Railroad reports, fishes, 12 (5) : 307-349.

1861. Notices of certain new species of North American Salmonidae, chiefly in the collection of the N.

W. Boundary Commission in charge: Archibald Campbell, Esq., Commissioner of the United States, collected
by Doctor C. B. R. Kennedy, Naturalist of the Commission. Ann. Lye. Nat. Hist. 7 : 306-313.

Thompson, R. B., and D. F. Tufts. 1967. Predation by the Dolly Varden and northern squawfish on hatchery-reared
sockeye salmon in Lake Wenatchee, Washington. Amer. Fish. Soc, Trans., 96(4) : 424—427.

Vladykov, V. D. 1954. Taxonomic characters of the eastern North American chars (Salvelinus and
Cristivomer). Canada, Fish. Res. Bd., J., 11(6) : 904-932.

Wales, J. H. 1939. General report of investigations on the McCloud River drainage in 1938. Calif. Fish Came, 25(4):
272-309.



REPRODUCTION AND SPAWNING OF NORTHERN ANCHOVY 175

Calif. Fish and Came 64 ( 3 ): 1 75-1 84 1 978

REPRODUCTION AND SPAWNING OF THE

NORTHERN ANCHOVY, ENGRAULIS MORDAX,

IN SAN PEDRO BAY, CALIFORNIA 1

GARY D. BREWER

Allan Hancock Foundation

University of Southern California

Los Angeles, California 90007

3

The gonosomatic index (GSI) was computed for samples of adult northern an-
chovy collected from the Los Angeles-Long Beach Harbor live-bait fishery during
1973 and 1974. GSI values were highest in February and March of both years and
declined to the lowest values in September. The abundance of anchovy eggs and
larvae in plankton samples taken from San Pedro Bay during the same period was
also highest in February and March and lowest during August and September.

Field and laboratory data suggest that within an environmental temperature range
of 13 to 18 C (55 to 66 F), northern anchovy have the potential to breed all year, but
are constrained to a seasonal reproductive cycle by dietary requirements that exceed
available production of zooplankton.

INTRODUCTION

Environmental investigations of the Los Angeles-Long Beach Harbor and San
Pedro Bay by the Allan Hancock Foundation, University of Southern California,
recognized the northern anchovy, Engraulis mordax Girard, as a key species,
both ecologically and economically, in southern California nearshore waters
(Soule and Oguri 1972-1976). This understanding prompted a summary of the
biology and fishery of £ mordax (Brewer 1975a) and a study on the thermal
tolerance and resistance of the fish (Brewer 1976). This paper is an outgrowth
of those studies. Data are given on the reproductive cycle and spawning of the
anchovy in nearshore waters off southern California. The results are discussed
in relation to environmental factors which may control anchovy spawning
throughout the fish's geographic range.

The northern anchovy is probably the most abundant fish in the California
Current (Mais 1974). A dramatic increase in anchovy biomass during the past
decade ( Smith 1 972 ) has led to an intensive effort to understand the biology and
population dynamics of this relatively unexploited resource (Calif. Dept. Fish
and Game 1971).

Comprehensive data on the reproduction of commercial fishes is a prerequi-
site for intelligent fishery management. Understanding the environmental factors
that influence spawning seasons and regulate fecundity in fishes is necessary if
fishery stocks are to be predicted and exploited wisely. Such information on
northern anchovy was, in part, detailed by Bolin (1936), Ahlstrom (1959, 1966,
1967), MacGregor (1968), Leong (1971), and Mais (1974). While Ahlstrom's
studies have compiled an enormous data bank on the seasonal occurrence and
distribution of anchovy spawning in offshore waters, California's bays, harbors,
and estuaries have been neglected. In light of man's increasing alteration of
shallow marine habitats for various industrial and recreational pursuits, it is
essential to understand the role that these areas play as spawning and nursery
grounds for fishes.

' Accepted for publication February 1978.



176



CALIFORNIA FISH AND GAME



MATERIALS AND METHODS

Samples of adult £ mordax were obtained from the Long Beach, California,
live-bait fishery between February 1973 and September 1974. The anchovy
live-bait fishery was described by Wood and Strachan (1970). Fish were meas-
ured to the nearest millimeter of standard length (sl) and weighed to the nearest
0.01 g after being lightly blotted. The left gonad of each fish, which is generally
larger than the right, was excised, blotted lightly, and weighed to the nearest 0.01
g. The gonosomatic index (GSI) was computed for each individual according
to the following formula: wet gonad weight/ wet specimen weight X 10 4 . Varia-
tions of the GSI have been used for a number of species as a measure of
reproductive maturity (Moser 1967; Khanna and Pant 1967; Mclnerney and
Evans 1970; Haydock 1971; Kaya 1973). By following monthly changes in the
weight of the testes and ovaries, as expressed by the GSI, reproductive matura-
tion can be estimated without time-consuming histological examination of the
gonads.

Bimonthly plankton collections for anchovy eggs and larvae were initiated in
February 1973 at 15 stations in the outer Los Angeles-Long Beach Harbor. Later,
more stations were added within the main channels of the inner harbor as well
as adjacent areas outside the harbor. Eventually, 22 stations were monitored
(Figure 1, Table 1). Each of the 561 plankton collections was standardized.
Samples were taken with a 0.5-m (1.7-ft), 222/x mesh (nylon) conical net,
towed at about 2 knots at a depth of 4 m (13 ft) (calculated by wire angle) for




Pacific Ocean



I I



I I I I



I



I I



I



I I



I



FIGURE 1. Los Angeles-Long Beach Harbor and San Pedro Bay with plankton tow station loca-
tions.



REPRODUCTION AND SPAWNING OF NORTHERN ANCHOVY



177



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