628 



Abstract. -White sturgeon, Aci- 

 penser transmontanus, adults (n=855) 

 were collected on their feeding grounds 

 in San Francisco Bay, California, and 

 their sex and stage of sexual maturity 

 were evaluated histologically. They did 

 not exhibit external sexual dimor- 

 phism, and the overall sex ratio did not 

 differ from 1:1. Average fork length was 

 139 cm ±1.1 cm (mean ± standard er- 

 ror of the mean); females were longer 

 (145 cm ±1.2 cm, n=443) than males 

 ( 133 cm ±1.0 cm, n=412). In smaller size 

 classes (<115 cm), males were signifi- 

 cantly (P<0.05) more numerous than 

 females. The proportion of females, 

 however, was significantly higher 

 among larger fish (>155 cm). The 

 sample of females consisted of 70% fish 

 with "immature" (previtellogenic) ova- 

 ries, 12% with "maturing" (vitellogenin 

 ovaries, and 18% with "ripe" (large, pig- 

 mented eggs) ovaries. In contrast, most 

 males were either "maturing" (meiosis, 

 56%) or "ripe" (spermatozoa, 39%). Ripe 

 females represented only 9% of all fish 

 sampled. Egg production by females, 

 estimated by hatchery spawning, aver- 

 aged 5,648 eggs/kg of body weight. The 

 length at which white sturgeon in San 

 Francisco Bay attain sexual maturity 

 was estimated to be 95-135 cm in fe- 

 males and 75-105 cm in males. The 

 duration of one ovarian cycle in itero- 

 parous females was estimated to be 

 longer than one year, with an appar- 

 ent 2- to 4-year interval between 

 spawning periods; the reproductive 

 cycle of males was estimated to be 1-2 

 years. The low reproductive potential 

 of white sturgeon in San Francisco Bay 

 should be considered in fishery man- 

 agement of the species. 



The reproductive condition of white 

 sturgeon, Acipenser transmontanus, 

 in San Francisco Bay, California 



Frank A. Chapman 



Department of Fisheries and Aquatic Sciences, University of Florida 

 7922 NW7I Street, Gainesville, Florida 32653 

 e-mail address FAA0GNVIFAS UFL EDU 



J. P. Van Eenennaam 

 S. I. Doroshov 



Department of Animal Science. University of California 

 Davis. California 95616 



Manuscript accepted 24 June 1996 

 Fishery Bulletin 94:628-634 ( 1996). 



White sturgeon, Acipenser trans- 

 montanus, have long been valued 

 for their caviar and flesh for human 

 consumption. Recently white stur- 

 geon have become popular as a rec- 

 reational fish (Galbreath, 1985; 

 Kohlhorst et al., 1991) and are be- 

 ing raised by commercial aquacul- 

 turists (Logan et al., 1995). During 

 the last four decades, researchers 

 have gathered sufficient informa- 

 tion on the biology of wild popula- 

 tions to improve management of the 

 fishery. Information now exists on 

 white sturgeon migratory patterns 

 (Miller, 1972; Kohlhorst et al., 

 1991), feeding habits (Schreiber, 

 1962; Semakula and Larkin, 1968; 

 McKechnie and Fenner, 1971; Mc- 

 Cabe et al., 1993), age, growth, and 

 population structure ( Semakula and 

 Larkin, 1968; Kohlhorst et al., 1980; 

 Brennan and Cailliet, 1991; Kohl- 

 horst et al., 1991; DeVore et al. 1 ). 

 Significant knowledge exists on 

 their reproduction, including go- 

 nadal development (North et al. 2 ; 

 Welch and Beamesderfer 3 ), natural 

 spawning (Stevens and Miller, 1970; 

 Kohlhorst, 1976; Parsley et al., 

 1993; McCabe and Tracy, 1994), ga- 

 mete and fertilization biology 

 (Cherr and Clark, 1985), and early 

 development (Beer, 1981; Wang et 

 al., 1987; Bolker, 1993). 



White sturgeon are anadromous 

 and endemic to Pacific estuaries 

 and coastal rivers of North America. 

 They are found from the Aleutian 

 Islands of Alaska to Monterey Bay, 

 California (Scott and Crossman, 

 1973). In the Pacific Northwest, 

 they are most abundant in the 

 Fraser, Columbia, and Sacramento- 

 San Joaquin rivers. The San Fran- 



1 DeVore, J. D., B. W. James, C. A. Tracy, 

 and D. H. Hale. 1993. Dynamics and 

 potential production of white sturgeon in 

 the Columbia River downstream from 

 Bonneville Dam. In R. C. Beamesderfer 

 and A. A. Nigro (eds. ), Status and habitat 

 requirements of the white sturgeon popu- 

 lations in the Columbia River downstream 

 from McNary Dam, vol. 1, report G, p. 137- 

 174. Final Report (Project No. 86-50) to 

 Bonneville Power Admin., Portland, Oregon. 



2 North, J. A., A. L. Ashenfelter, and R. C. 

 Beamesderfer. 1993. Gonadal develop- 

 ment of female white sturgeon in the lower 

 Columbia River. In R. C. Beamesderfer 

 and A. A. Nigro (eds. ), Status and habitat 

 requirements of the white sturgeon popu- 

 lations in the Columbia River downstream 

 from McNary Dam, vol. 2, report G, p. 109- 

 121. Final Report (Project No. 86-50) to 

 Bonneville Power Admin., Portland, Oregon. 



3 Welch, D. W., and R. C. Beamesder- 

 fer. 1993. Maturation of female white 

 sturgeon in lower Columbia River im- 

 poundments. In R. C. Beamesderfer and 

 A. A. Nigro (eds.), Status and habitat re- 

 quirements of the white sturgeon popula- 

 tions in the Columbia River downstream 

 from McNary Dam, vol. 2, report F, p. 89- 

 107. Final Report (Project No. 86-50) to 

 Bonneville Power Admin., Portland, Oregon. 



