Sunday, October 4, 2009

Good Steelhead Survival in the Columbia

Preliminary data released by NOAA fisheries is showing high migration survival for steelhead going through the Columbia hydrosystem in the spring of 2009. While the data is only preliminary and estimates of survival may still change a few percentage points, the current estimate of survival from Lower Granite Dam to below Bonneville is almost 70%, far exceeding the 2003-2008 average of 40%. The exact reasons for high survival are unknown although this year smolts headed out to Sea about two weeks earlier than average meaning many were allowed to migrate freely without barging. Good outmigrating conditions and excellent ocean productivity have resulted in a banner year for steelhead returns on the Columbia, lets hope next year brings the same.

While good outmigration survival is encouraging, it is important to remember it is not the norm. Mortality through the hydrosystem historically has been upwards of 10% of outmigrant smolts per hydroproject. Not until the outdated dams on the Snake are removed can we expect to make more than year to year gains on the overall downward trend in the Columbia system. More info at the Columbia Basin Bulletin.

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