143 



18 



Establish consistency in guidelines of different agencies 

 managing stocks in the Columbia River Basin. 



3.7.1 Donor Stock Source 



Hatchery stocks should be founded from carefully chosen donor 

 populations which have genetic resources and life history 

 patterns similar to the wild or natural stocks with which they 

 may genetically interact (Allendorf et al. 1990). 



IDFG and possibly WDW pennit an alternative approach of using 

 intentionally different hatchery stocks, along with methods to minimize 

 their interbreeding with wild and natural stocks. To ensure compatibility 

 with a genetic conservation goal, such an approach requires carefully 

 designed monitoring of (a) frequency of interbreeding and (b) incidence of 

 major behavioral or ecological interactions with wild and natural stocks 

 that may lead to indirect genetic impacts (section 4). Releases of large 

 numbers of sterile hatchery fish, for example, would require monitoring to 

 ensure that the majority of individuals are indeed sterile and do not 

 behaviorally or ecologically disrupt the fitness of natural or wild stocks. 



3.7.2 Adults Mated 



A. Prevent founder effects by ensuring that hatchery founders 

 represent a statistically significant sample of the donor 

 stock's gene pool. In every breeding season, maintain the 

 largest effective population size possible under the operating 

 constraints of a particular hatchery. 



These recommendations will serve to reduce losses of genetic variation in 

 hatchery stocks. Effective population size of a hatchery broodstock is 

 usually smaller than the actual number of parents mated. Degradation of 

 genetic variation due to reduced effective population size continues and 

 accumulates over consecutive generations. 



