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Nine Pinniped Deaths: What Happened?

Sea lion catching Columbia River salmon. Credit: Associated Press

By Allan Schreiber

The deaths of nine seals and sea lions over one weekend in early May remains under investigation two weeks later.  On the weekend of May 3, three Northern Elephant Seals, two Steller Sea Lions and four California Sea Lions died in two separate incidents. Some animals died as a result of gunfire, some while captive in holding cages.  Authorities from three states and the Federal government are investigating the events.

At the Piedras Blancas elephant seal rookery near San Simeon, CA, three northern elephant seals, each approximately two years old and weighing close to 1000 pounds, were shot to death as they hauled out on the beach.  Shots are believed to have been fired from a parking area on a bluff above the beach.

The rookery, which  first established itself in the 1990s, had become a popular  attraction.   Docents had left the area Friday afternoon and returned to find the animals lying in pools of blood on the beach Saturday morning. Necropsies were to retrieve bullets as forensic evidence and possible witnesses shot, but as of yet no clues have surfaced about the culprits or their motives. 

The following day, a thousand miles to the north on the Columbia River, six sea lions—including two threatened Steller sea lions—were found dead in cages near the foot of Bonneville Dam.  Marine mammals have gathered there for many years to feed on salmon which negotiate the fish ladders around the dam on their upstream journey to spawn.  Captured animals are usually taken to a marine park to be housed until the salmon migration has ended.  Originally believed to have been shot, authorities now say heat exhaustion was the cause of death to the sea lions.

According to the Portland Oregonian, agents of the state Department of Fish and Wildlife suspect the cage doors may have shut by accident, possibly when a drop of water level pulled taut the ropes which lift the doors. This would have trapped the animals inside the cages.

“Sea lions used to swimming in cold water could quickly overheat, even when air temperatures are not very high,” marine mammal experts said. “The animals' thick blubber, which insulates them from the cold ocean, could also act as an uncomfortable blanket when it's warm.”

Although Bonneville Dam has had numerous surveillance cameras installed since 9/11, none was trained on the cages nor were there any signs of tampering.

When the dead animals were first discovered, authorities assumed that they had been shot like the elephant seals in California.  Recent tensions in the mammals-versus-salmon conflict had flared, giving rise to the incorrect assumption. 

A federal court, citing the Marine Mammal Protection Act, had found against government agencies which were seeking  permission to shoot some of the animals and reduce predation of the endangered salmon. The court decision had angered recreational fishermen and Native American tribes whose access to fish is guaranteed by federal treaty.  According to an Associated Press report, representatives of local fishing interests were even preparing a legal defense fund for any parties arrested for shooting the mammals.

Although the cause of death of the sea lions has been discovered, the perpetrators of the elephant seal shootings in California are still unknown.


Elephant Seal: Credit: MojosCoast