After a frustrating week attempting to snare the ravenous California sea lions that are feeding on steelhead trout in the Seattle shipping channel, wildlife experts have given up trying to capture the pesky creatures, at least temporarily.
Six or more of these aggressive seal-like mammals have discovered that thousands of steelhead can easily be picked off in the urban seaway as the trout make their way into the fish ladders that bypass the ship locks. The locks lead to Lake Washington and the fish spawning beds in the Cedar River above the lake.
Sea lions were first seen feeding on the steelhead spawning run a year ago and were frightened off by exploding underwater "seal bombs," wildlife biologists reported. Attracted by the easy prey, they returned a month ago and this time the giant firecrackers failed to frighten them away, according to Curt Kraemer, a state Department of Game biologist.
With the help of the National Marine Fisheries Service, the state tried to net the elusive animals last week and again Monday, but each time the sea lions escaped as thousands of spectators watched.
Experts estimate that 100,000 sea lions live and breed along the California coast and about 1,000 of them migrate north into Puget Sound. Only a small number become troublesome, but, because they are protected by the Endangered Species Act, even these sea lions cannot be eliminated or harmed.
Washington officials wanted to truck any captured sea lions south to Santa Barbara and to release them near the Channel Islands even though the California Department of Fish and Game is opposed to the idea. Ultimately, it is the National Marine Fisheries officials who must decide where the sea lions can be released, if any are captured.
A sea lion, which can grow to 800 pounds, will consume 10% of its body weight a day, and biologists report that the sea lions at the fish ladders are consuming a dozen 15- to-20-pound steelhead a day. At that rate, they would consume 70% of the 2,000 or so steelhead that pass through the locks into Lake Washington and on up to the Cedar River, Kraemer said.
"We're unable to capture these sea lions," Kraemer said. During the first attempt, a 25-foot-deep net was stretched across the ship channel, trapping three sea lions, but the animals easily dived under the net that had been set in 35 feet of water. Embarrassed officials added another 10 feet to the net.
The trap was set again, temporarily trapping a lone sea lion on the second try last week. This animal escaped by wiggling under the net, then surfaced far down channel with a splash of its flippers as crowds of onlookers cheered.
On Monday, government officials made a third attempt, this time with the net modified to prevent a similar bottom escape, Kraemer said. Another sea lion was temporarily blocked behind the net and, after finding no other escape, the animal circled, swam furiously toward the net and leaped over to freedom. Further efforts to trap the sea lions were abandoned.
"All we can do now is fall back and regroup, try to figure out how we can capture them," Kraemer said. "We may modify the net, may try another net, but we don't even know yet for certain that we are going to try again this year."
In the meantime, hazing crews will continue to throw the exploding "seal bombs" in the water and try to herd the sea lions as far back out into Puget Sound as they can while the experts try to come up with another plan.