572 



Fishery Bulletin 94(3). 1996 



of juvenile coho salmon between fish from coastal riv- 

 ers and those from large inland river systems. They 

 concluded that these differences are coastwide and are 

 at least partially genetically determined. 



It is possible that there is some selective pressure 

 on the transferrin alleles occurring in large rivers, 

 because all the samples from the Fraser, Columbia, 

 Rogue, and Klamath rivers have high frequencies of 

 the *103 allele, and low frequencies of the *97 allele. 



Samples from California clustered with Columbia 

 River samples. California stocks may have been af- 

 fected by imported stocks: most of California's hatch- 

 ery stocks originated from eggs imported from Or- 

 egon (Bartley et al., 1992), primarily from hatcher- 

 ies on the Columbia River (Brown et al., 1994). 



In other areas, however, stocks appear to follow a 

 regional pattern of genetic differences, despite trans- 

 fers offish between geographical areas. For example, 

 the Bonneville and Klaskanine Hatcheries on the 

 Columbia River have received hatchery stocks from 



northern and southern Oregon ( Oregon Dep. Fish and 

 Wildlife 1 ), yet still remain most similar genetically to 

 other Columbia River samples ( Fig. 2 ). Again, this could 

 be due to selective factors unique to a given area. 



Our findings are similar to results from related 

 genetic studies of coho salmon. Noting allele frequen- 

 cies at 26 enzyme loci, Wehrhahn and Powell ( 1987) 

 also found significant differences between samples 

 from Vancouver Island and the southern coastal re- 

 gion of mainland British Columbia. In a study of 

 mitochondrial DNA variation in coho salmon from 

 Oregon, Currens and Farnsworth 2 found that Colum- 



1 Oregon Department of Fish and Wildlife. 1991. Lower Co- 

 lumbia River coho salmon, evaluation of stock status, causes of 

 decline, and critical habitat — Part 2. Report to ESAAdminis- 

 trative Record, 43 p., plus appendices. Available: Oregon Dep. 

 Fish Wildl., P.O. Box 59, Portland, OR 97207. 



2 Currens, K. P., and D. Farnsworth. 1993. Mitochondrial DNA 

 variation in Oregon coho salmon. Report to Oregon Depart- 

 ment of Fish and Wildlife, 12 p. Available: Oregon Dep. Fish 

 Wildl., P.O. Box 59, Portland, OR 97207. 



