96 



the Quileute River; and the scarcity of juveniles in most streams smaller than 

 the Columbia River (Stone, WDF, pers. count. ; Devore, WDF, pers. comm. ) • The 

 Lower Columbia population ie considered healthy and not apparently density- 

 dependent; that is, (1) nearly constant numbers of fish now reach fishable 

 sire each year, resulting in a population composed of fish of many ages, and 

 (2) individual growth rates are relatively rapid, compared to other 

 populations. Devore (WDF, pers. comm.) believes this implies that the habitat 

 is close to being fully seeded. 



White Sturgeon Population Status 



This species supports the majority of both sport and commercial fisheries in 



the Chehalis Basin. In response to reduced stock size (Figure 15), mar.&i; aer.t 



reduced harvest rates, which succeeded in reversing the decline and also 



increasing individual fish size. In 



particular, the directed commercial 



setline and gillnet fishery on the 



Columbia River has been eliminated, 



and commercial catch has been cut in 



half. Grays Harbor fisheries have 



also been more regulated and the July 



commercial fishery has been 



eliminated. The sport season remains 



open year-round (WDF 1992). 



Mathematical modeling indicates that 



the minimum and maximum sport size 



limits of 46 and 60 inches, effective 



both in the Chehalis Basin and on the 



Columbia River (WDF 1992), seem to be 



maintaining sustainable harvest and 



protecting spawning-sized females. 



Recent relatively level catches are thought to represent the optimum sustained 



yield (Stone, WDF, pers. comm.). 



Figure 15. Oifhilii Buin while tnd freen mirgeoo commercial 

 ludiofi. 



Catches in Grays Harbor probably come predominantly from the Columbia River 

 spawning stock., the only well-documented spawning population in Washington and 

 Oregon, although there is much white surgeon habitat available for potential 

 production in the Chehalis Basin in the form of cobbly riffles with high 

 velocity (J. Devore, FWS, pers. comm.). A few juveniles, apparently a few 

 months old, were seined from the main stem Chehalis during summer in the early 

 1970 's (John Wolfe, FWS, pers. comm.). Wolfe believes white sturgeon 

 historically occurred in the Chehalis up to the Newaukum. 



WDF's policy is to promote exclusively natural production, at least until the 

 potential for disease transmission in Columbia River experimental hatcheries 

 has been brought to manageable levels through research and development, and 

 the risk of genetic weakening through interbreeding with hatchery fish has 

 been adequately assessed (Devore, WDF, pers. comm.). 



39 



