HJORTand SCHRECK: PHENOTYPIC DIFFERENCES AMONG COIK) SALMON 



Table 8.— Means, standard errors (in parentheses), and ranges of morphological char- 

 acters for 1977 brood year samples of wild juvenile eoho salmon. Sample size was 12 for 

 all stream systems except Tenmile Lakes and Coquille River (15 each). The data are 

 listed in north to south order of the sampling locations. 



Stream system 



North Nehalem River 

 Nehalem River 

 Trask River 

 Nestucca River 

 Salmon River 

 Siletz River 

 Beaver Creek 

 Alsea River 

 Umpqua River 

 Tenmile Lakes 

 Coquille River 

 Rogue River 



Scales in 

 lateral 

 series 



Scale rows 



above lateral 



core 



Anal 

 fin 

 rays 



Gill 

 rakers 



Branchi- 

 ostegals 



Verte- 

 brae 



Table 4.— Hatchery stocks of coho salmon in which dif- 

 ferences in morphological characters occurred between the 

 1976 and 1977 brood years as determined by a two-sample test. 



Cascade-Bonneville 

 Cowlitz stock 

 Big Creek 

 Trask River 

 Salmon River 

 Alsea River 

 Umpqua River 



*P<0.05; "P<0 01 



that the stocks from large stream systems and 

 the southernmost stream systems had high fre- 

 quencies of the "A" allele, whereas the fre- 

 quencies in the smaller stream systems and 

 northern stream systems were highly variable. 

 Combining these two relationships helps explain 

 the pattern of transferrin gene frequencies. Fre- 



quencies of the "A" allele were high in stocks 

 from large stream systems regardless of lati- 

 tude, and in southern stocks regardless of stream 

 size. Stocks from smaller stream systems on the 

 northern Oregon coast and in Washington had 

 higher frequencies of the "C" allele. 



The factors affecting the patterns of trans- 

 ferrin gene frequencies in coho salmon stocks are 

 not known. However, Utter et al. (1980) sug- 

 gested that the frequencies may be influenced by 

 bacteriostatic properties associated with the dif- 

 ferent transferrin alleles. Genotypes of trans- 

 ferrin had differential mortality when exposed 

 to bacterial kidney disease in studies by 

 Suzumoto et al. (1977) and Winter et al. (1980b), 

 and to vibriosis, cold-water disease, and furun- 

 culosis in a study by Pratschner (1978). Trans- 

 ferrin genotype was also related both to differ- 

 ences in juvenile growth rates and to propensity 

 to return as jacks (Mclntyre and Johnson 1977). 



Ill 



