Sea Lion Lemonade
Some communities have simply embraced their uninvited guests.
"When you think about it, it's absolutely spectacular that people can observe these big predatory animals that closely, and have the opportunity to see them while eating lunch," says Bob DeLong, with NOAA's Alaska Fisheries Science Center, who has worked with sea lions since 1969.
European hunters centuries ago began driving sea lion numbers down, harvesting them for hides and blubber, and because they were rivals for fish. Today, these sea lions breed on offshore islands in southern California, but some also mate in the Farallones, off San Francisco, and on islands in Mexico. While females may nurse their young for much of the year, adult males tend to roam.
"It's that sexual separation that really sets things up for a lot of the conflicts that we see," DeLong says. "It's not the females; they're too busy making milk to feed junior to come up north and eat salmon or haul out on people's docks."
But males, after four or five years, travel far and wide, hightailing it to wherever they find food, sometimes as far north as Alaska. That appetite and wanderlust can bring a spot of trouble.
In 1989, after the Loma Prieta earthquake, a few sea lions chasing herring found their way to a new dock at San Francisco's Pier 39. Within a year, the number of sea lions topped several hundred, rendering the pier almost useless as a marina. Frustrated, boat users abandoned the yacht mooring spot to the lounging pinnipeds. Now Pier 39 sometimes attracts 1,700 or more sea lions and is "one of the most visited attractions following Disneyland," DeLong says.
"LaJolla just hasn't gotten used to what they have," he says. "There's lemonade to be made there."
That lemonade doesn't always come cheap. When sea lions amassed at Moss Landing Marina in California's Monterey Bay, "they sunk boats, they broke rails, smashed in doors; there was feces everywhere," says NOAA's Yates. After years of effort and thousands of dollars in damage, the harbormaster began installing special equipment to protect the structures. "It's expensive and hard, and it's a long painful process with angst on all sides."
And not all conflicts are with people.
Mysterious Hershel and Hondo Return
In the early 2000s, during one of the Columbia River's best salmon runs in decades, the Army Corps of Engineers noticed a few sea lions making their way to
Bonneville Dam, where they ate salmon, including chinook and steelhead, which are protected under the Endangered Species Act.
"There's no archaeological evidence that sea lions historically occurred in the Columbia," says Robin Brown, with Oregon Department of Fish and Wildlife.
At first it was an amusing head-slapper. The mammals usually appeared at the Columbia's mouth to snatch smelt. But with smelt numbers down and salmon up, the sea lions traveled upriver to the dam. Soon they were arriving by the hundreds, helping drive down fish populations. "The impact varies year to year, but it's potentially significant," Yates says.
Now, each spring, marksmen patrol the river, shooting sea lions with bean bags, rubber bullets, noisemakers, and firecrackers, trying to prevent one protected species from making a smorgasbord of the other. In extreme cases, the animals can be removed or killed.
Some animal-rights groups oppose this treatment, and many environmentalists suggest the focus on sea lions detracts from larger threats to the Columbia, namely habitat destruction upstream and dams that warm the water and complicate fish passage. But river and wildlife managers point to sea lions' history of doing damage when not kept in check.
In the 1970s, a pair of the pinnipeds, Herschel and Hondo, began gorging on endangered steelhead at a set of locks on Washington's Puget Sound. Within a decade, the problem was so severe that federal managers turned to crossbows and slingshots and specially prepared fish pumped full of nausea-inducing drugs in an attempt to turn the mammals off steelhead for good.
When that didn't work, they drove the sea lions away—literally—by capturing and trucking them out to the coast. The animals returned two weeks later. Later, the sea lions were dumped thousands of miles south in California's Channel Islands, but still found their way back. By the time the problem was controlled in the early 1990s, fewer than 100 of the winter steelhead run remained. Today those fish are all gone.
Scientists suspect the strandings of young sea lions in recent years ultimately will drive that marine mammal population down a bit in coming years. In addition, the return of white sharks and shortfin makos that prey on sea lions may also bring down sea lion populations. But scientists don’t believe that will ultimately help the endangered fish.
And recent winters have given researchers pause.
Unusually large populations of smelt have drawn record numbers of sea lions to an area near the mouth of the river. While hundreds swarmed the docks near the estuary in 2012, that number hit nearly 4,000 by 2016. But when the years of those bountiful smaller fish peter out, some experts fear they know what comes next.
"The sea lions will show up, expecting their smelt, but then see those large salmon swimming by and simply follow them up the river," Griffin says. "I believe that this problem will either stay the same or get worse."