156 



Fishes — Our Living Resoiines 



iiis.* «ir..«;^i^? 



Fifteen-hundred-pound white stur- 

 geon caught near Pavette, Idaho, 

 circa 1911. 



restrictions ha\'C been in place since 19X4 in 

 Idaho and IWO in British Cokniibia. 



Snake River 



The Snai^e River has 1 2 dams from its mouth 

 upstream to Shoshone Falls in Idaho. White 

 sturgeon are beheved to exist in small numbers 

 in the lower three pools on the Snake River 

 formed by Ice Harbor, Lower Monumental, and 

 Little Goose dams (Zinicola and Hoines 1988). 

 Of the nine impoundments upstream from Little 

 Goose Dam, white sturgeon are relatively abun- 

 dant in two, present at low numbers in si.x. and 

 are absent in another (PSMFC 1992). 



Although little is known about the early life 

 history and spawning habitat requirements of 

 white sturgeon in the Snake River, the construc- 

 tion and operation of the river's dams are likely 

 to have the same effects as the impoundments 

 on the Columbia and Kootenai rivers. White 

 sturgeon appear more abundant in regions of the 

 Snake River where free-flowing river habitat 

 exists (PSMFC 1992), such as between Lower 

 Granite and Hells Canyon dams where 76% of 

 the river is free-flowing. Conversely, white stur- 

 geon are not present in the impoundments cre- 

 ated by Hells Canyon Dam and not abundant in 

 the impoundment created by Oxbow Dam. 

 which constitute two continuous slackwater 

 regions (Welsh and Reid 1971 ). 



While free-tlowing sections of the Snake 

 River exist in varying proportions between the 

 dams, impoundments upstream of these sec- 

 tions influence both water temperature and the 

 annual discharge pattern. At least 28 sturgeon 

 died during July 1990 because of low dissolved- 

 oxygen levels in Brownlee Pool (PSMFC 

 1992). Sturgeon production in the Snake River 

 also appears limited by dewatering from irriga- 

 tion diversions (Lukens 1981 ) and small spawn- 

 ing populations (Cochnauer et al. 1985). 



Harvest of white sturgeon from the Snake 

 Ri\er has had a definite negative impact on 

 these populations, but the magnitude of the 

 cftect is unknown. Commercial fishing was per- 

 mitted on the Snake River until 1943; then 

 increasingly restrictive regulations were imple- 

 mented from 1944 to 1969. In 1970 catch and 

 release regulations were impo.sed on the entire 

 river. A recommendation has been made that 3 

 of the 12 reaches of the Snake Ri\er discussed 

 in this article be completely closed to fishing 

 (Cochnauer et al. 1985). 



Summary 



Habitat changes (e.g., decreased discharges 

 resulting in decreased spawning habitat) caused 

 by development of the hydropower system have 

 contributed to white sturgeon population 

 declines in the Columbia River Basin; spawning 

 habitat has been particularly affected by dams. 



Overharvest of white sturgeon has caused 

 population declines in several Columbia River 

 Basin populations, both historically and in the 

 past two decades. Recent management changes 

 have helped alleviate overharvest in much of the 

 Columbia River Basin, but refinement of man- 

 agement strategies is still needed in some areas. 



The status of the 25 Columbia River Basin 

 white sturgeon populations varies considerably: 

 I is stable and abundant; 5 are relatively abun- 

 dant, but probably at lower levels than in the 

 past; 12 are sparse and many are declining; 5 

 have unknown status but creel data suggest they 

 are sparse; 1 is sparse, declining, and listed 

 under the Endangered Species Act; and white 

 sturgeon have probably been extirpated from 

 another. Conditions that have contributed to 

 stock declines in other white sturgeon popula- 

 tions are present in populations whose status is 

 unknown, suggesting that populations with 

 unknown status may also be declining. 



References 



Apperson. K.A., and P.J. Anders. 1990. Kootenai River 

 white sturgeon investigations and experimental culture, 

 annual progress report 1989. Bonneville Power 

 Administration, Division of Fish and Wildlife Project 88- 

 65. 50 pp. 



Artyukhin. Y.K.. A.D. Sukfioparova. and L.G. Fimukhira. 

 1978. The gonads of sturgeon, Acipenser giildenstiidti. in 

 the littoral zone below the dam of the Volograd water 

 engineering system. Journal of Ichthyology 18:912-923. 



Beamesderfer. R.C.. and T.A. Rien. 1993. Dynamics and 

 potential production of white sturgeon populations in 

 three lower Columbia River reservoirs. Pages 175-206 in 

 R.C. Beamesderfer and A. A. Nigro. eds. Status and habi- 

 tat requirements of the white sturgeon populations in the 

 Columbia River downstream from McNary Dam. Vol 1 . 

 Final Report to Bonneville Power Administration, 

 Portland. OR. 



