Although four of the 48 sea otters captured to date have died, U.S. Fish and Wildlife Service experts said they will continue efforts to establish a breeding colony of this threatened species in the waters off San Nicolas Island.
In all, 70 otters are to be relocated from the San Luis Obispo coastline to San Nicolas, 70 miles southwest of Los Angeles, as a hedge against an oil spill that could wipe out the primary populations along the coast, officials explained.
The four otter deaths over the weekend were not unexpected, according to experts, who suspect stress as the cause.
"We knew there would be some mortalities . . . given the ambitious nature of this project," said William Maxwell, California Department of Fish and Game otter expert who is monitoring the federal effort to ensure the otters' survival.
3 Were Males
Three of the dead otters were males that had been captured and transported by air to San Nicholas. Two of the males died in the holding pens just offshore before their release; the third body washed ashore after the initial 22 were released late last week, according to Skip Ladd, director of the federal Fish and Wildlife Service relocation effort.
The fourth victim was a young female that died Sunday while being held in a Monterey aquarium before transport, Ladd said.
"We don't believe that four losses . . . out of 48 captures is unusual or an inordinately high number. . . . It is within the expected levels of mortality," Ladd said. While the causes of death have not been established, early autopsy results indicate that stress may have been a factor, according to Ladd. "There is some indication from other studies that perhaps males don't do as well as females (under stress)."
As a result of the deaths, Ladd said, the recovery teams' capture and relocation techniques are being re-evaluated to see if there are ways to reduce the stress caused by capture and handling.
Using small, open boats, the relocation teams capture the otters either by using nets or by sending divers into the kelp beds with underwater trapping devices. The captured otters are then held in a Monterey aquarium until 24 are in captivity, Ladd explained.
The second group of 24 otters is being held in Monterey and will be flown 225 miles south to San Nicolas within a few days, he said. Once there, they will be placed in the special holding pens offshore to let them adjust to the new location before they are released.
Because the otters have no protective layers of fat, they depend on their thick fur to keep them warm in the cold ocean waters, Ladd explained. If this fur is fouled by oil, the animals quickly die of exposure. Establishment of a second colony outside the heavily traveled shipping lanes is considered essential to the otters' survival, he said.
"While we are deeply saddened at the loss of the otters, we have always known there was an element of risk whenever wild animals are subject to capture and handling," said Carol Fulton, executive director of Friends of the Sea Otter. "The effort is still well worth the risk. We now have 21 sea otter again swimming in the waters surrounding San Nicolas Island."