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Sea Lions' Death: Humans in the Clear

by Lynda Mapes
Seattle Times, February 6, 2009

(Benjamin Brink) Sea lions linger on cage platforms set up by Washington and Oregon state officials at Bonneville Dam in late April. Six sea lions died last year when the doors of two cages inadvertently shut and trapped them. But humans didn't shut the doors either by accident or on purpose, investigators have found.

The trapping is a federally authorized effort by Washington and Oregon to remove California sea lions identified as regular predators of federally protected chinook salmon below Bonneville Dam on the Columbia River. Some 80 sea lions, which return to feast on the fish year after year, have been trapped, marked with a brand, and identified for removal, either by relocation to an aquarium. If that's not possible, they've been put down. The conclusion by investigators still reviewing the deaths is based on their review of video tapes, witness testimony and other evidence gathered since the animals were trapped below the dam last May.

The National Marine Fisheries Service, which is in charge of protecting the animals, has learned from the incident, said Brian Gorman, spokesman for the agency. This March, when the states of Washington and Oregon begin trapping the animals once more, they will use cages with a different design.

This year, doors will have a lock that can only be opened or closed by a combination-operated device similar to a garage opener. And no cage with an animal in it may be left unattended by a person.

Last year, latches were simple mechanical devices and the doors were secured open with a rope. The traps were left open and unattended to get the sea lions acclimated to them, so officials could more easily catch the animals later.

The animals were discovered dead during a routine check. The doors had closed accidentally some three hours earlier, investigators believe. They said a shift in the river level by three feet; entanglement by the sea lions in the ropes, or the animals shifting their weight in the cages might have shut the doors.

The animals probably panicked, overexerted themselves, and over heated, because of their two-inch thick layer of blubber, according to the fisheries service.

It's believed the animals eat more than 4,500 chinook a year. Other problems causing salmon runs to decline, include dams, which hinder migration and injure juveniles; development that destroys habitat, and overfishing.

Related Sites:
Necropsy report

Lynda Mapes
Sea Lions' Death: Humans in the Clear
Seattle Times, February 6, 2009

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