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16 



3.5.2 Adults Mated 



Artificial selection: WDF-2 and chapter 1 of WDF-1 call for maintaining the 

 genetic diversity of the donor stock in the hatchery stock by avoiding 

 artificial selection unless "specifically directed to do so." WDF-1 explains 

 that gametes should be collected from representative portions of each run, 

 based on return date, size and age. WDF-2 goes on to specify that jacks 

 should be included in the spawning population "at a level of 2% of the total 

 number of both male and female fish spawned that day." While this is 

 explained to offset the distortion in frequency of jacks caused by fishing 

 gear selectivity and hatchery rearing conditions, rationale for a constant 

 value of 2% in all cases is missing. Adherence to one value may be flawed 

 for genetic conservation and long-term stock perpetuation. 



Neither document gives a policy for specific conditions which warrant 

 intentional selection, although WDF-1 appropriately urges definition of 

 goals and follow-up assessment of effects of any selection program. To be 

 consistent with a genetic conservation goal, any directed selection program 

 should begin with small-scale experimentation and careful monitoring 

 (sections 3.7.4.B and 5). 



Number of parents: WDF-1 advises a minimum size of 200 parents when 

 "the number of returning adults is not a limiting factor." This 

 recommendation of one minimum value needs to be balanced by advice to 

 maximize the number of parents, taking into consideration the operating 

 constraints of a particular hatchery (section 3.7.2. A) and the demographics 

 of the donor stock (section 3.7.5). 



Sex ratio: WDF-1 advises a 1:1 sex ratio with no provision for exceptions. 

 Yet WDF-2 recommends a male to female ratio of 1:3 when: the number of 

 available parents is not limiting, more than 0.5 million eggs will be taken 

 on a g.iven day, and the egg surplus will be shipped to another facility. 

 Justification for this advice is not provided. It is fiawed in terms of genetic 

 conservation and long-term sustainability of stocks involved (section 

 3.7.2.A). 



3.5.3 Fertilization Protocol 



WDF-1 and WDF-2 caution against sequentially adding milt from different 

 males to a lot of eggs from several females because this has been shown to 

 lead to unequal sex ratios. Both documents therefore recommend pooling 

 milt from a number of males in a separate container, and then fertilizing 



