Oncorhynchus gorbuscha

Because of the fixed two-year life cycle, individuals spawning in a particular river system in odd and even years are reproductively isolated from each other and have developed into genetically different lines; in some river systems, such as the Fraser River in British Columbia, only the odd-year line exists in significant numbers; in Bristol Bay, Alaska, the major runs occur in even years (areas in between have runs in both even and odd years) (Heard 1991). An electrophoretic study by Varnavskaya and Beacham (1992) found that "pink salmon from the Fraser River and southern British Columbia were distinct from more northerly spawning populations in British Columbia, Alaska, and Kamchatka. The concept of a 'fluctuating stock' population structure of pink salmon or ramdom mixing during spawning over a large geographic area was not supported by observed patterns of genetic variation." In Russia, in contrast, lack of distinct stocks in different areas has been inferred from the lack of biochemical genetic differention detected in some surveys (see Varnavskaya and Beacham 1992).

Has hybridized with chinook salmon in the St. Marys River, Michigan (Rosenfield 1998).

Phylogenetic analysis based on mtDNA data indicates a sister relationship between pink salmon and chum salmon (Domanico and Phillips 1995).

Still widespread and locally common around the margins of the North Pacific Ocean.

During ocean feeding and maturation, pink salmon range throughout the North Pacific Ocean and Bering Sea north of about 40 degrees north latitude. Populations originating from different coastal regions of the North Pacific occupy distinct ocean nursery areas. The range shifts southward for winter, northward in warmer months (Heard 1991).

Spawning occurs in most tributary rivers of northeastern Asia (Korea to Siberia) and in North America from California and Oregon (rare in these states) north to the Aleutian Islands and Mackenzie River delta, Arctic and Pacific drainages. Arctic populations do not appear to be self-sustaining but may be expanding and so warrant monitoring. The species has been introduced in the Great Lakes, Newfoundland, and several European areas.

In the southern part of the range, the most significant runs are in streams tributary to Puget Sound. This salmon has been recorded from various streams in northern California, but spawning in California has been rarely observed and only in the lower Russian River. Many recent sightings of adults in California may be represent strays from rivers to the north (Nehlsen et al. 1991).

In a survey of populations in the contiguous U.S., Huntington et al. (1996) identified only five healthy native stocks, all in Washington.

See GTRENDCOM. Tolerates a surprising amount of disturbance in spawning habitat.