Tuesday, March 4, 2014

Increased Winter Time Flow Boosting Hanford Reach Wild Chinook

A new study has documented dramatic increases in the number of juvenile Chinook produced in the Hanford Reach following a series of agreements that have led to increased winter flows. Flows in the interior Columbia were historically very low during winter, and the agreements have created artificially high flows during the period when fry are incubating in river gravels designed to maximize fry survival. Historically, the abundance of wild fall chinook in the Columbia would have been supported and maintained by fish spawning throughout the mainstem and its many tributaries. However, with the construction of mainstem dams starting the in 1930's all of the mainstem spawning habitat has been lost with the exception of the Hanford reach which now supports the largest remaining spawning aggregation of wild fall chinook in the Columbia. Consequently, managers have been looking for ways to maximize productivity in this population and have apparently been successful at doing so using artificially high winter flows.

More information in the Columbia Basin Bulletin:


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