Ocean abundance (before any fisheries) of Columbia River early and late run coho is expected to be more than three times larger than last year. A forecast released this week by the Technical Advisory Committee says ocean abundance this year should total 964,100 adult fish as compared to a final estimate of 301,500 for the 2013 run.
The 2003-2012 annual average return to the mouth of the Columbia, which subtracts ocean harvest and other mortality, is 434,100 fish, according to the July 2013 joint staff report produced by the Oregon and Washington departments of fish and wildlife.
The 2014 forecast include an ocean abundance estimate of 526,600 Columbia River early-run fish and 437,500 late-run coho as compared to 190,800 and 110,700 estimates respectively last year.
Coho adults are typically age-3 fish, and return to freshwater after only one year in the ocean. Early stock coho enter the Columbia River from mid-August to early October with peak entry occurring in early September. In the ocean, early stock coho tend to remain near the Oregon and southern Washington coasts and most migrate southward from the Columbia River and are therefore referred to as Type S.
Late stock coho enter the Columbia River from mid-September through December with peak entry occurring in mid-October, according to the joint staff report. In the ocean, late stock coho tend to migrate northward from the Columbia River along the Washington coast and Vancouver Island, and are therefore referred to as Type N.
Columbia River coho return primarily to Oregon and Washington hatcheries downstream from Bonneville Dam, although substantial hatchery and some natural production now occurs in areas upstream of Bonneville Dam.
Historical natural coho production areas above Bonneville Dam include the Spokane, Yakima, Wenatchee, Entiat, Methow and Snake rivers. The majority of coho presently passing Bonneville Dam are from the U.S. v. Oregon Management Plan mandated hatchery releases of lower river coho stocks in the Yakima, Klickitat, Wenatchee and Methow rivers in Washington, the Umatilla in Oregon and Idaho’s Clearwater river.
The releases outside the Klickitat are primarily intended to restore naturally producing coho to appropriate habitats above Bonneville Dam, most recently in the Snake, Yakima, Methow, and Entiat rivers. Coho destined for areas above Bonneville Dam have represented an increasing percentage of the total return in response to increased releases above Bonneville Dam.