REISENBICHLER and PHELPS: GENETIC VARIATION IN CHINOOK AND COHO SALMON 



salmon are raised in one federal, one state, and 

 two tribal hatcheries along the north coast. Sam- 

 ples were taken from six hatchery populations 

 (Table 1). 



mouths of the rivers. At the hatcheries, samples 

 of tissue were taken within 3 hours after the fish 

 were killed for spawning. Adults from the fish- 

 eries were not available to us until they had been 



Table 1 . — Run times and stock origins for hatchery populations used in genetic 



characterization. 



'From Houston (see text footnote 3). 



Sample Collection 



Fish were collected during 1983 from the 21 

 areas identified in Figure 1 (some juvenile Chi- 

 nook salmon were also available from collections 

 made in 1982). Juvenile fish at hatcheries were 

 collected with dip nets at several locations along 

 each raceway containing the fish to be studied. 

 Juveniles in streams were collected by trapping, 

 electrofishing, and seining. A few juvenile coho 

 salmon (usually <15 in each age group) were 

 taken from each of several sites throughout each 

 drainage. Juvenile chinook salmon were taken 

 from several sites in the lower portions of the 

 rivers. Juveniles of both species were collected 

 from areas where no hatchery fish were released 

 or before hatchery fish were released; they were 

 either kept alive or held on ice for up to 8 hours 

 and then frozen at -10°C or -70°C until thawed 

 for electrophoretic analysis. 



Samples of tissue from eye, liver, white muscle, 

 and heart were taken from adult fish spawned at 

 hatcheries or caught in gill net fisheries at the 



delivered to wholesale fish buyers. Some fish 

 were delivered more than a day after the fish 

 were killed; although most were kept on ice or 

 refrigerated during this interval, some isozyme 

 activity was lost. Tissue samples from all adults 

 were placed on ice within 30 minutes after exci- 

 sion and were frozen at -10°C or -70°C within 

 6h. 



Electrophoresis 



We used horizontal starch-gel electrophoresis 

 (Utter et al. 1974; May et. al. 1979) to assay fish 

 tissues. Eye, heart, liver, and muscle tissues were 

 removed from partly thawed juveniles just before 

 electrophoretic analysis. We identified alleles at 

 loci encoding specific enzymes, using the staining 

 methods of Harris and Hopkinson (1976) and 

 Allendorf et al. (1977). The nomenclature used to 

 describe the gene loci and the allele variants fol- 

 lowed Allendorf and Utter (1979). 



Of the 40 enzymes examined, 30 had sufficient 

 activity and resolution to be used in this study 



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