The major contribution of SPA was to provide the first quantitative estimates of the relative proportions of Asian and North American sockeye salmon migrating in area southwest of 46°N, 175°W in the North Pacific Ocean. Estimates derived from samples collected in 1972-1976 indicated that most of the maturing and immature sockeye salmon migrating in this region are of Russian (Kamchatka Peninsula) origin (an estimated 70-100%), but that the area of intermingling of continental stocks is wider than shown by tag recoveries (hypothetical extension of the range of North American sockeye salmon throughout the area south of 46°N, between 160°E-170°E). A more recent analysis of samples collected in 1990 from the area southwest of 44°N, 174°E indicated relatively high proportions of Bristol Bay sockeye salmon (36% of age-2.3 sockeye salmon). The SPA results, however, have yet to be verified by tag experiments or other direct evidence. Decadal-scale fluctuations in climate and the abundance of major populations may affect the extent of intermingling of Asian and N. American sockeye salmon in offshore areas.

SPA conducted by the Fisheries Agency of Japan after 1978 did not contribute substantially to information on the ocean distribution, migration patterns, and abundance of chum salmon in the area southwest of 46°N, 175°W. The scientists who conducted the studies suspected bias in their analyses. Information from tag recoveries was also inconclusive, but showed that distributions of Asian and North American chum salmon overlapped only in the eastern sector of the area (175°E-175°W). On the basis of this limited information, International North Pacific Fisheries Commission (INPFC) scientists concluded in a joint report that most of the chum salmon in the area southwest of 46°N, 175°W are of Asian (Russian and Japanese) origin.

Similar to the results for sockeye salmon, however, SPA showed a broader overlap in distribution of Asian and North American chum salmon in the area south of 46°N than is indicated by tag experiments. Recent genetic stock identification analyses of chum salmon in research vessel catches in the central and western North Pacific Ocean also indicate that ranges of Asian and North American stocks overlap in these regions. Tag experiments have substantiated the results of SPA by Canadian scientists in the 1960s that were the first to detect Asian chum salmon in the eastern Gulf of Alaska. Clearly, additional stock identification research is needed to better understand the distribution and relative abundance of Asian and North American chum salmon in the North Pacific Ocean.

A study of chum salmon bycatch in the U.S. eastern Bering Sea-Aleutian Islands trawl fishery in 1994 provided the first opportunity to compare the results of SPA and genetic stock identification. Scale pattern estimates of regional stock composition were similar to those of an independent allele frequency analysis by US government scientists. Both studies provided significant new information on ocean distribution, migration patterns, and abundance of Asian and North American chum salmon in the eastern Bering Sea. Contrary to the results of high seas tagging research conducted before 1978, the results of the scale pattern and genetic studies showed that immature North American chum salmon migrate to the Bering Sea in summer. Recent recoveries of coded-wire tagged chum salmon originating from southeast Alaska, British Columbia, and Washington in summertime catches by trawl fisheries in the eastern Bering Sea partly substantiate these results. The results of both SPA and genetic studies confirm that this region of the eastern Bering Sea is an important migratory pathway for adult chum salmon and a major rearing area for immature chum salmon from multiple regions throughout the North Pacific Rim.

Similar to the results for sockeye salmon, SPA contributed significant new information on the range of North American coho salmon in the North Pacific Ocean southwest of 46°N, 175°W, which is a major offshore rearing area for coho salmon during their last summer at sea. On the basis of the combined results of SPA and tag experiments, INPFC scientists concluded that intermingling of Asian and North American (primarily western Alaskan) coho salmon occurs in the area between 170°E and 175°W, and that the proportion of North American fish (primarily western Alaskan stocks) in this area may be higher than is indicated by the recovery of high-seas tags. The quality of Asian scale samples in some of the analyses was not always good, and this may have affected SPA results. Improved stock proportion estimates are needed to better understand the dynamics of coho salmon carrying capacity in this remote region, particularly in areas of enhanced biological productivity over the Northern Emperor Seamount Chain.

The determination of ocean distribution, migration patterns, abundance, and stock origins of chinook salmon on the high seas has always been hindered by the low abundance of this species in salmon research vessel catches. The combined results of SPA, parasitological analysis, and tag experiments, however, indicate extensive overlap in the ocean ranges of Russian and North American chinook salmon across the Bering Sea south of 62°N, between 175°E and 165°W and in the North Pacific Ocean from 160°E to 145°W. All stock identification methods have indicated that in the Bering Sea, western Alaskan chinook salmon (including Canadian Yukon fish) are the most abundant regional stock group. SPA results indicate that both Asian and North American chinook salmon are present in the area southwest of 46°N, 175°W, and that Russian (Kamchatka Peninsula) chinook salmon predominate in the area west of 174°E. These results have yet to be validated by tag experiments or other direct evidence. There are significant gaps in information on distribution, migration patterns, abundance, and stock origins of chinook salmon in the offshore waters of the eastern North Pacific Ocean south of 50°N, between 130°W-170°W.