Construct a Portable Sea Lion Trap

The purpose for this project was to fabricate a trap to deploy in the Bonneville Dam pool to remove the California sea lions in that area. These sea lions cannot move below the dam on their own and while residing in the Bonneville pool, they are feeding on listed and non-listed salmon and steelhead.

CRITFC procurement processes were followed to purchase the trap components. The trap was moved to Bonneville Dam and is waiting for fall deployment.
(Figure 1) provides the necessary tool to remove sea lions that are confined upstream of Bonneville Dam and are preying on salmon. The project scope was just to purchase the trap, deploying the trap will be the in-kind contributions from ODFW and WDFW.
Removing these nuisance sea lions that are currently residing in the Bonneville pool will reduce predation impacts to listed and unlisted salmon stocks originating upstream.

Two to four California sea lions are residing in the Bonneville pool. These animals cannot move downstream past Bonneville Dam. These sea lions are feeding on anadromous salmonids and other fish. This project complements the primary goal of Wy-Kan-Ush-Mi Wa-Kish-Wit to improve and restore anadromous fishes to rivers and streams that support historical cultural and economic practices of the tribes.

Removal of these nuisance California sea lions will potentially benefit all anadromous fish stocks originating upstream of Bonneville Dam, since they will no longer be exposed to this predation in the Bonneville pool. The daily median estimated individual salmonid biomass requirement for California sea lions based on bioenergetics modeling is 14.2 kg (95% confidence interval of 7.8 to 27.1 kg/day), which translates into a median of 3 chinook salmon/day (Brown et al. 2013). This suggests that potentially 4,380 salmon could be saved from removal of these animals based on 4 animals eating 3 fish/day x 365 days. Since salmonids are not in high abundance in the area 365 days a year, the actual impact may be slightly less, however, during times of low anadromous salmonid abundance, sea lions likely won’t be fasting, increasing the chances of impacts to other species such as sturgeon. Tribal fishers will directly benefit from removal of these sea lions. We have received numerous reports of damaged gear and loss of catch as a result of interactions with these California sea lions.

It should be recognized that trap and removal of sea lions in the Bonneville Dam pool is a short-term solution to a problem. The sea lions likely moved into the pool through the navigation lock. After discussions with the U.S. Army Corps of Engineers, they agreed to develop and implement locking protocols that should minimize opportunity for sea lions to pass upstream in the future. If sea lions do pass through the lock in the future, we will have a tool (this sea lion) to address the problem.