Government: Overheating may have killed sea lions

PORTLAND — The deaths of federally protected sea lions found in traps at Bonneville Dam on the Columbia River may be due to overheating.

Government wildlife specialists made that conclusion after their review of the necropsies conducted on the six protected sea lions.

Studies of tissue samples taken after the May 4 deaths are expected in about 10 days and may reveal more.

Oregon and Washington had been trapping the animals as part of a federally approved removal process to reduce sea lion's impact on salmon at the dam.

The Humane Society of the United States questioned Wednesday whether the 60-degree weather at the time would kill animals that can survive worse.

The National Marine Fisheries Service initially reported the animals had apparently been shot and said later that investigators were pursuing theories that someone in a boat had gone to the traps and used a high-powered rifle to dispatch the sea lions, the bullets passing through the flesh.

The service's initial reports about the deaths raised intense interest in the long-running dispute over the sea lions, which prey on protected salmon, and as a consequence, the government and the Humane Society made an agreement to suspend trapping and removing the sea lions this year.