The Jan 29 2010 issue of Science has a 2-page report on the Central California Coho salmon. Since being listed in 2004 as an endangered species in this region around San Francisco (approx Santa Crus to Fort Bragg) the species has continued to decline, with particularly poor runs in the last two years. The 2009/2010 winter spawning run is now coming to a close and results indicate that adult returns have been dismal for the third year in a row. Since Coho have a 3 year life cycle between hatching and returning to the spawning grounds it means that all three "year classes" are affected. Numbers of returning adults are about 10-fold lower than in 2004 with counts in one of the least affected rivers showing only 64 adults this year.
In addition to issues with land use, dams etc, recent delays in marine upwelling of deep nutrient rich waters along the coast and the 3 year drought are believed to be important factors in the rapid decline. Efforts to improve habitat are being made but little can be done about the latter two problems. Let's hope the tide turns in time to allow these fish to make a comeback.
Bart
