Species and Community Profiles - San Francisco Estuary ...

maxima ranged from 22-33° C. As further evidence
of the general hardiness of the species, splittail appear
to be tolerant of low dissolved oxygen levels and strong
water currents.
Splittail are numerous within small dead-end
sloughs, those fed by freshwater streams, and in the
larger sloughs such as Montezuma and Suisun (Daniels
and Moyle 1983). Juveniles and adults utilize shallow
edgewater areas lined by emergent aquatic vegetation.
Submerged vegetation provides abundant food sources
and cover to escape from predators. Shallow, seasonally
flooded vegetation is also apparently the preferred spawning
habitat of adult splittail (Caywood 1974).
References
Aceituno, M.E., M.L. Caywood, S.J. Nicola and W.I.
Follett. 1976. Occurrence of native fishes in
Alameda and Coyote Creeks, California. Ca. Dept.
Fish and Game 62(3):195-206.
Bailey, H. 1994. Culturing studies on splittail.
IEP Newsletter, Summer 1994. p. 3.
Caywood, M.L. 1974. Contributions to the life history of
the splittail Pogonichthys macrolepidotus (Ayres).
Master’s thesis. Ca. State Univ., Sacramento.
Daniels, R.A. and P.B. Moyle. 1983. Life history of
the splittail (Cyprinidae: Pogonichthys macrolepidotus
(Ayres)) in Sacramento-San Joaquin estuary. U.S.
Natl. Marine Fish. Bull. 81: 647-654.
California Department of Water Resources and U.S. Bureau
of Reclamation (CDWR and USBR). 1994.
Effects of the Central Valley Project and State
Water Project on Delta smelt and Sacramento
splittail. Prepared for U.S. Fish and Wildl. Serv.,
Ecol. Services, Sacramento, CA.
Herbold, B. 1987. Patterns of co-occurrence and resource
use in a non-coevolved assemblage of fishes. Ph.D.
dissertation. Univ. of Ca., Davis.
Meng, L. and N. Kanim. 1994. Endangered and threatened
wildlife and plants; proposed determination
of threatened status for the Sacramento splittail.
Fed. Reg. 59:004: 862-868.
Meng, L. and P.B. Moyle. 1995. Status of splittail in
the Sacramento-San-Joaquin estuary. Transactions
of the Amer. Fisheries Society 124: 538- 549.
Sommer, T.R., R. Baxter and B. Herbold. 1997. The
resilience of splittail in the Sacramento-San Joaquin
Estuary. Transactions of the Amer. Fisheries Society
126: 961-976.
Young, P.S. and J.J. Cech. 1996. Environmental tolerances
and requirements of splittail. Transactions
of the Amer. Fisheries Society 125: 664-678.
General Information
Chinook Salmon
Oncorhynchus tshawytscha
Lt. Dante B. Maragni
The Chinook salmon (Family: Salmonidae) is morphologically
distinguished from other Oncorhynchus species
of the northern Pacific Ocean by its large size, small black
spots on both caudal fin lobes, black pigment along the
base of the teeth (McPhail and Lindsey 1970 as cited in
Healey 1991), and varying shades of flesh color from
white through shades of pink and red (Healey 1991).
The Chinook salmon life history (Figure 2.6) is characterized
by adult migration from the ocean to natal
freshwater streams to spawn, and juvenile migration
seaward as smolts in their first year of life. During the
smoltification process, juvenile Chinook salmon undergo
physiological, morphological, and behavioral changes
that stimulate emigration and prepare them for life in
the marine environment (Healey 1991).
The Sacramento-San Joaquin Chinook salmon of
California exists as four races—winter, spring, fall, and
late-fall—as defined by the timing of adult spawning migration
(Mason 1965, Frey 1971, Moyle 1976, Healey
1991). In 1989, the Sacramento River winter-run Chinook
salmon was listed as threatened under the federal
Endangered Species Act by the National Marine Fisheries
Service (NMFS) (54 FR 32085). NMFS reclassified
the winter-run as endangered in 1994 (59 FR 440)
based on: 1) the continued decline and increased variability
of run sizes since its listing as a threatened species
in 1989, 2) the expectation of weak returns in certain
years as a result of two small year classes (1991 and
1993), and 3) continuing threats to the population. The
State of California listed the winter-run as endangered
under the California Endangered Species Act in 1989.
In 1995, the Oregon Natural Resources Council and R.
Nawa petitioned NMFS to list Chinook salmon along
the entire West Coast, including the States of California,
Idaho, Oregon, and Washington, under the federal
Endangered Species Act (54 FR 32085). The State of
California presently includes on its list of species of special
concern the late-fall (Class 2– special concern) and
the spring-run (Class 1– qualified as threatened or endangered)
Chinook salmon. Spring-run Chinook salmon
Chapter 2 — Estuarine Fish and Associated Invertebrates 91
Moyle 1976
Fish