Tuesday, July 28, 2009

Fraser River Sockeye Run a Bust

In a year that biologists and managers had predicted strong returns, the Fraser River Sockeye run is going bust. Fraser Sockeye abundance normally cycles on a four year basis, and while this year should have been a strong run the fish are yet to materialize leading to a significant downward revision in the run forecast. The Fraser has multiple distinct runs of Sockeye, all of which appear to be seeing lower than expected returns. With recent high temperatures, Summer Sockeye the largest component of the run will be subject to potentially lethal river temps over 20 C. While it is impossible to blame one factor for the poor returns, development of fish farms in the Georgia Strait is likely sevely impacting outmigrant sockeye smolts and in recent years high prespawn mortality in adult sockeye has meant that many fish aren't even reaching the spawning grounds. High prespawn mortality has been attributed to in river temperatures however some researchers believe disease may be contributing. Salmon farms along the migratory corridor may be increasing the incidence of disease among returning adults. See more information in the Vancouver Sun.


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