Information developed during recently completed evaluations of the status of seven species of anadromous Pacific salmonids (Oncorhynchus spp.) in the Pacific Northwest was used to characterize patterns of intraspecific diversity along three major axes: ecology, life history and biochemical genetics. Within the study area, the species' ranges, and therefore the number of distinct ecological regions inhabited differ considerably, with pink and chum salmon limited to the northern areas and chinook salmon and steelhead distributed over the widest geographic range. The species showed comparable differences in the patterns of life history and genetic diversity, with chinook and sockeye salmon and steelhead having the most major diversity groups and pink, chum and coho salmon having the least. Both life history and genetic diversity showed a strong, positive correlation with the extent of ecological diversity experienced by a species, and the correlation between the number of major genetic and life history groups within a species was even stronger (r=0·96; P<0·05). Departures from these general diversity relationships found in some species (especially sockeye and coho salmon and cutthroat trout) can be explained by different interactions with the freshwater environment and, for cutthroat trout, by the occurrence of substantial intrapopulational diversity in life history traits, a hierarchical level not considered in this study.

A computer oriented approach to the collection and analysis of morphometric characteristics in juvenile chinook salmon (Oncorhynchus tshawytscha) is described. A three-step data collection and storage method is used whereby X–Y coordinate data for relevant morphological features on a body form are collected with a digitizing pad and used to calculate morphometric characters. To test this method, I calculated two morphometric data sets, a conventional and a truss network, and compared them by multivariate analysis in a preliminary study of growth and development in one hatchery stock of fish, and in a survey of population differences in three naturally occurring populations of chinook salmon. Technical advantages of using a digitizing pad for collecting morphometric data are demonstrated. Hatchery-reared chinook salmon showed marked changes in body shape during the period of spring smoltification when marked changes in condition factor occurred. Multivariate differences were discerned among the three Oregon coastal stocks. Truss data provided more specific information concerning shape changes in the study of early development and produced greater between-group differences in the geographic survey. The results of these preliminary analyses can be applied to problems of identifying smolt status in hatchery fish and stock origin in mixed-stock fisheries.

We resolved allozyme variation among 28 enzymes encoded by 58 protein loci in 27 samples of sockeye salmon and kokanee Oncorhynchus nerka in the Pacific Northwest. Of 32 polymorphic loci, 16 were polymorphic at the P0.95 level (frequency of the common allele ≤0.95). We found substantial variation at mAAT‐1* and mAH‐1,2*, loci not previously described in O. nerka in this portion of its distribution. Mean heterozygosity per sample ranged from 0.010 to 0.036 and averaged 0.028 over all samples. Wrightˈs fixation index (FST) averaged 0.153 over 16 P0.95 loci, indicating considerable allele frequency variation among samples. The pattern of population differentiation of sockeye salmon, as revealed through genetic distance and principal component analyses, resembled a mosaic in that nearest geographic neighbors were not necessarily similar genetically. Allele frequencies at two to five loci differed significantly between sympatric sockeye salmon and kokanee in three separate localities, indicating genetic and reproductive distinctiveness of the two sympatric forms. Sockeye salmon from Redfish Lake (Sawtooth Valley, Idaho) were of particular interest because of their extensive freshwater migration and extremely low abundance in recent years. We found no evidence that any of the recorded stock transfers of O. nerka into the Sawtooth Valley (Redfish and Alturas lakes) have had a genetic impact on populations surveyed here. The O. nerka from Sawtooth Valley presently occupy a distinctive position in multilocus space, particularly with respect to mAH‐1,2*, mAAT‐l *, and ALAT*. Continued studies of O. nerka in the Sawtooth Valley are focusing on juvenile outmigrants and “residual” sockeye salmon.