Who Killed The Sea Lions At Bonneville Dam?

By Dennis Newman

One of the strangest stories from last year was the death of six sea lions that were accidentally trapped at Bonneville Dam.

The sea lions were stuck in the traps, unmonitored, for several hours. And by the time someone showed up to check on them, they were all dead.

So who or what killed them?? A investigation by NOAA Fisheries says it was a fluke accident.

Courtesy: NOAA

The trapping was part of a federally approved plan to reduce the numbers of sea lions who camped out at Bonneville Dam to feast on salmon.

(See our earlier story: Salmon Hungry Sea Lions Put On Notice.)

The idea was to capture the worst offenders, the sea lions who ate the most salmon. After capture, officials would try to find new places for them to live, such as zoos or aquariums. Some of the sea lions who were captured early on were sent to Texas and California. But for sea lions that couldn’t find a home, the plan was to put them to death.

Here’s what happened to these six, according to NOAA.

On May 4, six sea lions were in two traps when the doors slammed shut on them. NOAA’s investigation rules out human causes. It says there’s no evidence of human tampering with the traps, or a human mistake that caused the doors to close by accident.

The investigation concludes the doors were jarred closed, probably by rapidly changing river levels, movements by the sea lions, or that the doors’ trip lines became entangled.

The sea lions were stuck there for several hours and without access to the cold waters of the Columbia River, they died from becoming overheated. NOAA says stress may have played a role, too.

Despite the rocky start to the program, State and Federal officials plan to start capturing sea lions again on March 1st. That’s about the time salmon hungry sea lions return to Bonneville Dam for the spring runs.

Federal courts have ruled against animal rights groups that wanted to stop the capture and kill program. In 2007, it’s estimated the sea lions ate about 4% of the salmon trying to pass by the dam.