467

CALIFORNIA DEPARTMENT OF FISH AND GAME

December 2001

California’s Living Marine Resources:

A Status Report

White Sturgeon

History of the Fishery

Historically, the white sturgeon (Acipenser transmontanus) resource has been very important to Californians. Sturgeon scutes and skull plates are found in Native 

American middens in the San Francisco Bay, SacramentoSan Joaquin delta, and Elkhorn Slough areas, indicating 

that these large sh were important sources of tribal 

nutrition. An early commercial shery developed for white 

sturgeon between the 1860s and 1901, stimulated by a 

growing acceptance of smoked sturgeon and caviar on 

the East Coast of North America. The California harvest 

was concentrated in the San Francisco Bay and delta. 

Fishing gear included gillnets, longlines, and multiple 

unbaited hooks for snagging sturgeon. The commercial 

catch peaked at 1.65 million pounds in 1887, declined 

to 0.3 million pounds in 1895, and to 0.2 million pounds 

in 1901, when the commercial shery was closed. Small 

commercial catches in a reopened shery from 1909 to 

1917 indicated that white sturgeon populations were still 

low, and commercial shing ceased in 1917.

Sport shing for white sturgeon was legalized in 1954, 

with a 40-inch total length minimum size limit and a one 

sh per day per person creel limit. In 1956, snagging for 

sturgeon was outlawed and the minimum size limit was 

raised to 50 inches through 1963. The small sport shing 

catch increased dramatically in 1964 when the minimum 

size reverted to 40 inches and bay shrimp were discovered 

to be effective bait. By 1967, 2,258 sturgeon were landed 

by party boat anglers. Possibly due to reduced stocks of 

other estuarine and coastal marine species such as striped 

bass, angling for white sturgeon has become very popular. 

Although exact sport catch data are not available, the 

California Department of Fish and Game (DFG) estimates 

that the harvest rate during the 1980s was 40 percent 

greater than it was during the previous two decades. 

In 1990, a 72-inch maximum size limit became law and 

the minimum size limit was increased by two inches per 

year until a new minimum size of 46 inches was reached 

in 1992.

Status of Biological Knowledge

White sturgeon are generally found in estuaries, and their range extends along the Pacic Coast of North 

America from Ensenada, Mexico, to the Gulf of Alaska. 

However, spawning populations have been found only 

in large rivers from the Sacramento-San Joaquin system 

north. Indeed, most California white sturgeon are found in 

the San Francisco Bay estuary. Some white sturgeon move 

into the delta and lower Sacramento River during late-fall 

and winter. Some of these sh move up the Sacramento 

River to the Knights Landing-Hamilton City area to spawn. 

Spawning may also occur in the Feather River, but has not 

yet been documented there. A small number move up the 

San Joaquin River. The Klamath River supports the other 

California subpopulation of white sturgeon. Although most 

recoveries from a tagging program in the San Francisco 

Bay estuary have come from the estuary and its tributaries, a few sh (less than one percent of total recoveries) 

have moved along the Pacic Coast and been recovered in 

Oregon and Washington.

California white sturgeon grow rapidly when young, reaching 12 inches fork length in one year. This rapid growth 

slows thereafter and they reach the present minimum 

legal size of 46 inches after nine to sixteen years. Subsequently, they grow one to 2.5 inches per year. Ages and 

growth rates of eld-caught sh have been determined 

from the number and spacing of annular rings, visible in 

sections of rst pectoral n rays. Laboratory experiments 

have shown that young-of-the-year white sturgeon growth 

is affected by water temperature and dissolved oxygen 

concentration. They grow signicantly faster at 68°F than 

at 59°F, but an increase to 77°F does not signicantly 

increase growth rate. When dissolved oxygen concentrations drop to 56 percent of air saturation at any of 

these three temperatures, juvenile sh show a signicant 

decrease in growth rate, presumably due to reduced 

food consumption. The white sturgeon’s rapid growth rate 

has attracted the interest of some California aquaculturists, who grow sturgeon in freshwater tanks which have 

consistently moderate temperatures and high dissolved 

oxygen concentrations. 

The largest sturgeon were caught before 1900 when size 

records were vague. However, the largest of these sh 

was probably more than 13 feet long and weighed more 

than 1,300 pounds, making white sturgeon the largest 

freshwater-inhabiting sh in North America. This sh may 

have been 100 years old. The largest white sturgeon captured in California waters during the past 40 years was 

a 468-pound sh caught by a sport angler in Carquinez 

Strait in 1983. This sh is the present world record sportcaught white sturgeon. In a University of California, Davis 

(UCD) study of white sturgeon during the 1980s, many sh 

were caught, measured, examined for sex and stage of 

maturity, and released. Median male size was 3.6 feet and 

median female size was 4.6 feet in San Francisco Bay. 

White Sturgeon, Acipenser transmontanus

Credit: DFG

White Sturgeon
468

CALIFORNIA DEPARTMENT OF FISH AND GAME

December 2001

California’s Living Marine Resources:

A Status Report

White Sturgeon

Compared with most freshwater or anadromous shes, 

white sturgeon are quite old when they become sexually 

mature, but they evidence impressive fecundity at this 

large size. In the UCD study during the 1980s, sexually 

mature males were 3.6 to 6.0 feet long (nine to 25 

years old), whereas mature females were generally 4.6 to 

6.6 feet (14 to 30 years old). However, high natural variability in the size at sexual maturity was noted, especially 

among females. For example, the smallest pre-spawning 

female white sturgeon weighed only 25 pounds, whereas a 

120-pound female was caught which, from gonadal analysis, was determined to have not yet spawned. Studies suggest that white sturgeon females do not spawn every year. 

Several years may lapse between successive spawnings 

in an individual female. In the study on San Francisco 

Bay sh, approximately 50 percent of the males captured 

were approaching spawning condition for that year, compared with only about 15 percent of the captured females. 

Fecundity varies with female size. Smaller females (under 

ve feet) contain about 100,000 eggs, whereas a 9.2-foot, 

460-pound female contained 4.7 million eggs.

Spawning occurs in the Sacramento River between midFebruary and late May when water temperatures are 46° 

to 72°F. Little is known about spawning behavior. White 

sturgeon spawn their eggs onto deep gravel rifes or rocky 

holes in the Sacramento River. The fertilized eggs are very 

adhesive and hatch after four to 12 days on the bottom. 

Larvae stay close to the bottom and rear in both the river 

and the estuary downstream. Rearing location is at least 

partly determined by river ow; more larvae are washed 

into the estuary when freshwater ows are high. Young 

juvenile sturgeon become increasingly tolerant of brackish 

water as they grow and develop.

White sturgeon feed on a wide variety of bottom-dwelling 

animals. Sturgeon feed by suction with their ventral, protrusible mouths. Dense aggregations of taste buds on their 

four barbels presumably assist in identication of food 

on the bottom. When their mouths are blocked by food, 

white sturgeon can ventilate their gills by ushing water 

in via the dorsal part of the gill slit and out via the 

ventral part. Young sturgeon (eight inches) feed primarily 

on small crustaceans such as amphipods and opossum 

shrimp. As they develop, they take a wider variety of 

benthic invertebrates, including various species of clams, 

crabs, and shrimp. Larger white sturgeon diet includes 

shes and, during winter in San Francisco Bay, herring roe.

Little is known about predators on white sturgeon. Smaller 

sh are undoubtedly taken by various sh and bird predators, although the ve lines of bony scutes along their 

bodies probably make them less desirable prey than other 

estuarine species. Anglers undoubtedly mount the largest 

predatory effort on adult sh.

Status of the Population

The 19th century history of white sturgeon shing in California waters shows this species’ vulnerability 

to overshing. Delayed sexual maturity and infrequent 

spawning by the females exacerbates this vulnerability 

compared to many other shes. DFG tagging studies indicated that angler harvest was high during the 1980s and 

new size limits (including initiation of a rst-ever maximum size limit in 1990) reect DFG’s management concerns. Annual harvest rate estimates indicate that the 

angling regulation changes begun in 1990 have had the 

desired effect: harvest rates have been reduced by at 

least half from the levels of the mid- to late 1980s

Adult (at least 40 inches total length) white sturgeon 

abundance, as estimated from tagging studies, varied 

greatly between 1967 and 1998. The abundance estimate 

reached its highest level (142,000) in 1997. This abundance 

pattern is largely the result of irregular recruitment to the 

adult population by highly variable year classes. Strong 

year classes are produced in years with high spring freshwater outows from the Sacramento-San Joaquin Delta, 

so much of the present high white sturgeon abundance is 

attributable to the very wet 1982-1983 period.

Unfortunately, the severe drought that gripped California 

from 1987 to 1992 will soon begin to affect the adult 

white sturgeon population, because reproductive success 

was low in most of those years. The strong year classes 

from the early 1980s were recruited starting in about 1994 

and, by 1997 and 1998, few sh smaller than the minimum 

size limit of 46 inches were caught. Thus, the population 

should decline substantially as recruitment almost ceases 

and growth and mortality reduce the abundance of sh 

now in the shable population. However, another cycle 

of strong recruitment can be expected when sh from a 

series of wet years starting in 1993 begin to enter the 

shery late in the next decade.

The present low exploitation rates, past rapid recoveries 

from population lows in the mid-1970s and early 1990s, 

and current protection of the most fecund females by the 

72-inch maximum size limit suggest that no further angling 

restrictions are needed at this time.

David W. Kohlhorst

California Department of Fish and Game

Joseph J. Cech, Jr.

University of California, Davis
469

CALIFORNIA DEPARTMENT OF FISH AND GAME

December 2001

California’s Living Marine Resources:

A Status Report

References

Cech, J.J. Jr., S.J. Mitchell, and T.E. Wragg. 1984. Comparative growth of juvenile white sturgeon and striped 

bass: Effects of temperature and hypoxia. Estuaries 

7:12-18.

Chapman, F.A. 1989. Sexual maturation and reproductive 

parameters of wild and domestic stocks of white sturgeon, 

Acipenser transmontanus. Ph.D. Dissertation, University of 

California, Davis.

Chapman, F.A., J.P. Van Eenennaam, and S.I. Doroshov. 

1996. The reproductive condition of white sturgeon, 

Acipenser transmontanus, in San Francisco Bay, California. 

Fishery Bulletin 94:628-634.

Kohlhorst, D.W. 1980. Recent trends in the white sturgeon population in California’s Sacramento-San Joaquin 

Estuary. California Fish and Game 66:210-219.

Kohlhorst, D.W., L.W. Botsford, J.S. Brennan, and G.M. 

Cailliet. 1991. Aspects of the structure and dynamics 

of an exploited central California population of white 

sturgeon (Acipenser transmontanus). Pages 277-293 in: 

P. Williot, editor. Acipenser. Actes du premier colloque 

international sur l’esturgeon, Bordeaux, France.

Kohlhorst, D.W., L.W. Miller, and J.J. Orsi. 1980. Age and 

growth of white sturgeon collected in the Sacramento-San 

Joaquin Estuary, California: 1965-1970 and 1973-1976. California Fish and Game 66:83-95.

Miller, L.W. 1972a. Migrations of sturgeon tagged in 

the Sacramento-San Joaquin Estuary. California Fish and 

Game 58:102-106.

Miller, L.W. 1972b. White sturgeon population characteristics in the Sacramento-San Joaquin Estuary as measured 

by tagging. California Fish and Game 58:94-101.

Schaffter, R.G. 1997. White sturgeon spawning migrations 

and location of spawning habitat in the Sacramento River, 

California. California Fish and Game 83:1-20.

Schaffter, R.G. and D.W. Kohlhorst. 1999. Status of 

white sturgeon in the Sacramento-San Joaquin Estuary. 

California Fish and Game 85:37-41.

White Sturgeon

Angler holding a white sturgeon

Credit: DFG