Marine Mammal Predation in the Lower Columbia River

The intent and focus of this project is to address marine mammal predation on Columbia River salmonids.  This is a new and growing impact to salmonids particularly in the last several years (Pinniped Task Force 2007). To date, most of the attention has focused on the area just below Bonneville Dam, where salmon are concentrated before they enter the fish ladders and where visual estimates of predation rates are easier to develop (Stansell et al. 2011). Over the last two years (2010-11) sea lions killed over 10,000 salmonids within a viewable distance of Bonneville Dam.  However, there are anecdotal reports of extensive sea lion predation in areas below the dam that are not visible from the dam. This unaccounted for predation may be greater than the observed predation. This project addresses objectives required under the Hydro System Biological Opinion Reasonable and Prudent Actions (RPA 49 and 69).  These objectives include 1. Conduct boat-based non-lethal sea lion hazing in the Bonneville Dam tailrace annually generally between March 1 and May 31; 2. Develop a system to enumerate sea lions and estimate predation throughout the lower Columbia River; and, 3. Track movements of individual sea lions at various spatial scales in the Columbia River using acoustic telemetry.