Tuesday, March 27, 2012

Managers Forecasting Large Returns for Oregon and California Coasts

Buoyed by strong ocean conditions, managers are predicting strong numbers of Chinook and coho bound for rivers along the Oregon and California Coasts this summer, prompting longer fisheries than have been seen in recent years. Fisheries south of the mouth of the Columbia are supported in large part by three major salmon producing rivers, the Rogue, Klamath and Sacramento and all three are predicted to see much better than normal returns of Chinook this summer and fall. Despite the good news managers should remain cautious when setting seasons for sport and commercial fisheries off the coast. Preseason forecasts are made in part based on the number of jacks - fish which have spent only one summer in the ocean - that returned in previous years. Since most chinook return after 2, 3 or even 4 years at sea managers can then use jack numbers to create a rough estimate of marine survival for each outmigrating cohort of fish. However, these estimates rely on the assumption that the proportion of any given cohort returning as jacks is constant and in recent years higher than normal returns of jack salmon have led to a high degree of uncertainty for preseason forecasts.

More info in the Columbia Basin Bulletin:

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