139 



"whenever possible, we will continually integrate our hatchery and naturally 

 spawning broodstock to maintain a hatchery stock which is capable of successfully 

 surviving through natural production." 



-^13 Rearing Practices aPFG-l) 



The following policy is relevant to rearing practices: 



"Hatchery production goals will be set and manipulated by water temperatures, 

 feeding rates, and general hatchery practices to produce and plant smolts of a size 

 which has produced the highest percentage of returning adults in test programs." 



Currently, target smolt sizes are similar to natural smolt size for chinook 

 salmon and larger than natural smolt size for steelhead (Steve Yundt, IDFG, 

 personal communication). Maintenance of naturally existing genetic 

 variation for smolt size, a quantitative trait, is important to ensure 

 adaptive evolution and long-term perpetuation of a stock (section 1.2.1.B). 

 Targeting one smolt size may cause inadvertent reduction in genetic 

 variation for this trait and genetically correlated life history traits, thus 

 jeopardizing sustainability of high adult return rates in future generations. 

 . This practice therefore warrants careful review. A statement on page 9 of 

 IDFG-1 acknowledges that "hatchery selection", including "accelerated 

 rearing" could eventually pose a threat to stock persistence, particularly if 

 timing, age composition, or fecundity of runs are altered. 



3.3.4 Size of Remaining Donor Stock gPFG-n 



This issue is addressed by mandating that no more than two-thirds of a 

 natural spawning run will be trapped to build hatchery broodstock in 

 order to leave the remaining third for natural reproduction. The use of 

 one minimum value for all natural spawning runs is a rough estimate, with 

 no clear underlying rationale (Steve Yundt, IDFG, personal communication). 

 Differences in historical patterns of genetic variation and population 

 dynamics of different natural runs may dictate different minimum values 

 in order to conserve their genetic resources and life history patterns. 



3.4 Guidelines in ODFW Documents 



The Wild Fish Management component of ODFW-1 mandates management 

 of hatchery broodstocks so that either: (a) interbreeding with wild 

 populations is impossible; (b) where interbreeding of released hatchery 

 fish and wild fish is possible, hatchery fish "are maintained to be 

 genetically similar to the wild population"; or (c) except for fish genetically 

 similar to the wild population, hatchery fish "that spawn at the same time 



