154 



FimIu's — Our Living Resimrces 



For further information: 



Leo F. Marnell 



National Biological Service 



Midcontinent Ecological Science 



Center 



Glacier Field Station 



Glacier National Park 



West Glacier, MT 3993(1 



that forni their headwaters in Glacier National 

 Park (Tables 1 and 2). Native cutthroat trout 

 were not found east of the Continental Divide in 

 the Missouri River or South Saskatchewan 

 River drainages within the park. 



In addition to genetic concerns, ecological 

 disturbances associated with the presence of 

 introduced fishes have compromised the native 

 westslope cutthroat fishery. Fish are no longer 

 stocked in park waters; however, several waters, 

 including some that contain undisturbed native 

 fisheries, remain vulnerable to invasion by non- 

 native migratory species. Introduced kokanee 

 salmon iO. nerka). a specialized planktivore, 

 are believed to be competing with juvenile 

 stages of native trout in some waters, especially 

 during periods of winter ice cover when plank- 

 ton may be limited. Predation by introduced 

 lake trout {Scilvellniis luiwayciish) has also been 

 implicated in the decline of native cutthroat 

 trout in several large glacial lakes in the North 

 and Middle Fork drainages (Marnell 1988). 

 Native cutthroat trout have been compromised 

 by fish introductiinis and invasions throughout 

 about 84% of their historic range in Glacier 

 National Park (Marnell 1988). 



Although native cutthroat trout have been 

 adversely affected throughout a large portion of 

 their park range, the species has not been lost 



from any water where it was historically pre- 

 sent. Glacier National Park remains one of the 

 last strongholds of genetically pure strains of 

 lacustrine (i.e.. lake-adapted) westslope cut- 

 throat trout. This fact could have important 

 implications for reestablishment of this unique 

 subspecies throughout the central Rocky 

 Mountains, where this trout has disappeared 

 from most of its original range. 



References 



Marnell, L.F 1986. Impacts of hatchery stocks on wild fish 

 populations. Pages 339-347 in R.H. Stroud, ed. Fish cul- 

 ture in fisheries management. American Fisheries 

 Society. Bethesda. MD. 



Marnell. L.F. 1988. Status of the westslope cutthroat trout in 

 Glacier National Park, Montana. American Fisheries 

 Society Symposium 4:61-70. Bethesda, MD. 



Marnell, L.F, R.J. Behnke, and FW. Allendorf. 1987. 

 Genetic identification of cutthroat trout {Sabno clarki) in 

 Glacier National Park, Montana. Canadian Journal of 

 Fishenes and Aquatic Sciences 44:1830-1839. 



Moyle, PB.. H. Li, and B.A. Barton. 1986. The 

 Frankenstein effect: impact of introduced fishes in North 

 America. Pages 415-426 in R.H. Stroud, ed. Fish culture 

 in fishenes management. American Fisheries Society, 

 Bethesda, MD. 



Taylor, J.N.. W.R. Courtenay, Jr.. and J.A. McCann. 1984. 

 Known impacts of e.xotic fishes in the continental United 

 States. Pages 322-373 in W.R. Courtenay, Jr., and J.R. 

 Stauffer, eds. Distnhution, biology, and management of 

 exotic fishes. Johns Hopkins University Press, Baltimore, 

 MD. 



Columbia 

 River Basin 

 White 

 Sturgeon 



by 



Allen I. Miller 



Timothy D. Coiuiihaii 



Michael J. Parsley 



Lance G. Beckman 



National Biological Service 



White sturgeon (Acipenser transmontamts). 

 the largest freshwater fish in North 

 America, live along the west coast from the 

 Aleutian Islands to central California (Scott and 

 Grossman 1973). Genetically similar reproduc- 

 ing populations inhabit three major river basins: 

 Sacramento-San Joaquin, Columbia, and Fraser, 

 The greatest number of white sturgeon are in 

 the Columbia River Basin. 



Historically, white sturgeon inhabited the 

 Columbia River from the mouth upstream into 

 Canada, the Snake River upstream to Shoshone 

 Falls, and the Kootenai River upstream to 

 Kootenai Falls (Scott and Grossman 1973: 

 Figure). White sturgeon also used the extreme 

 lower reaches of other tributaries, but not exten- 

 sively. Current populations in the Columbia 

 River Basin can be divided into three groups: 

 fish below the lowest dam. with access to the 

 ocean (the lower Columbia River): fish isolated 

 (functionally but not genetically) between 

 dams: and fish in several large tributaries. 



The Columbia River has supported impor- 

 tant commercial, treaty, and recreational white 

 sturgeon fisheries. A commercial fishery that 

 began in the 1880"s peaked in 1892 when 2.5 

 million kg C5.5 million lb) were harvested 

 (Craig and Hacker 1940). By 1899 the popula- 

 tion had been severely depleted, and annual har- 

 vest was very low until the early 1940's. but the 



population recovered enough by the late 1940"s 

 that the commercial fishery expanded. A 1.8-m 

 (6-ft) maximum size restriction was enacted to 

 prevent another population collapse. Total har- 

 vest doubled in the l97(J"s and again in the 

 I980"s because of increased treaty and recre- 

 ational fisheries. From 1983 to 1994. 15 sub- 

 stantial regulatory changes were implemented 

 on the mainstem Columbia River downstream 

 from McNary Dam as a result of increased fish- 

 ing. Columbia River white sturgeon are still 

 economically important. Recreational, commer- 

 cial, and treaty fisheries in the Columbia River 

 downstream from McNary Dam were valued at 

 $10.1 million in 1992 (Tracy 1993). 



Several factors make white sturgeon rela- 

 tively vulnerable to overexploitation and 

 changes in their environment. The fish may live 

 more than 100 years (Rieman and Beamesderfer 

 1990). and overexpolitation is well documented 

 for long-lived, slow-growing fish (Ricker 

 1963). Female white sturgeon are slow to reach 

 sexual maturity: in the Snake River they mature 

 at age 15-32 (Cochnauer 1981 ). Mature females 

 in the Columbia Basin only spawn every 2-11 

 years (Stockley 1981: Cochnauer 1983; Welch 

 and Beamesderfer 1993). Sustainable harvest 

 levels vary for impoundments in the Columbia 

 River. Several impoundments are managed as 

 groups, making overexploitation more likely in 



