Warm water imperils young sea lions
Over the past few months, local beaches have been an increasingly vibrant place for the senses. But one of the unpleasant new sights (and smells) are an unusual number of sea lion carcasses—more than ever before, and not just on the beaches of Santa Cruz.
Emaciated sea lion pups have been washing up all along the California coast, and while some are still alive, the numbers are overwhelming the few centers equipped to nurse them back to health.
The animals being rescued are typically around eight months old, says Dr. Shawn Johnson, lead veterinarian at Marine Mammal Center in Sausalito, “and half the weight they are supposed to be.” Sea lions, he says, will typically stick with mom until about their eleventh month.
Pups have been rescued from beaches all the way up to Bodega Bay, and the Sausalito base is the only one on this side of Northern California that handles live “strandings”—instances when marine mammals wash up on shore. Long Marine Laboratory, for instance, is a member of the Marine Mammal Stranding Network, but only handles dead strandings, and the Monterey Bay Aquarium focuses entirely on sea otters.
“In a normal year, during this time period we would’ve seen zero to three [dead] California sea lions, and we’ve responded to 12 as of today,” says Teri Sigler, Marine Mammal Stranding Coordinator at Long Marine Laboratory. “We’ve definitely seen an increase, but we’re not inundated in the way that the Marine Mammal Center is.”
The Sausalito center expects the wash-ups to continue for months to come. For the third year running, pups have been driven out of the Monterey Bay and Channel Island rookeries before being weaned.
Johnson blames the rising ocean temperatures, which have been running 2 to 5 degrees Celsius above average, from the Aleutian Islands all the way down to Baja California, despite the apparent absence of an El Niño trigger.
The warming trend has dispersed the anchovies and sardines that sea lions rely on, he says. “The sea lion moms are not eating too much themselves, but they are putting lots of effort into finding food. They can’t keep up.”
If they can scarcely feed themselves, their pups go hungry. Now the center is scrambling to handle 170 pups currently on site during what’s usually a slow time of year at the world-class animal-rescue center.
Johnson says there are usually 10 to 15 animals on site in January and February—sea otters, sea lions, harbor seals. That’s about how many sea lion pups are now coming into the center every week. In early March, there were about 170 in the facility—and more on the way. Almost 1,000 pups have been found stranded this year.
The center houses a full-scale veterinarian hospital and necropsy lab on the site of an old Nike missile base.
An outdoor pen finds about eight pups huddled on a heating pad. “We had to buy the heating pads,” says Johnson. “The little ones aren’t usually here this time of year.”
Where you’d expect blubbery beasts, you see instead the animals’ ribs. “They should still be in the Channel Islands nursing,” says Johnson.
Once the pups get their strength back, they are transferred to a saltwater pool to get them ready for the journey back to the sea. Between 50 and 60 percent of the pups that come to the Sausalito center are released back to sea at Point Reyes National Park. The rest wind up at zoos and aquariums, or they die.
“This is normally the slow season,” says Johnson. He says a more typical winter morning would find vets, researchers and other staff catching up on scientific papers and maintenance projects around the facility.
Earlier in the morning, Johnson had a conference call with a biologist at the Channel Islands—and the news from Southern California was not good. “We are bracing to be at or near capacity in a few weeks, and it’s making us all very nervous,” says Johnson. “It’s bad timing.”
Volunteers have been called in to the Sausalito Marine Mammal Center, which issued an online SOS for additional volunteers. The center was coming up short on medicine and food, so there’s been a push in fundraising at the nonprofit, whose annual budget is around $6.5 million.
Temporary volunteers are put to work in the spacious “fish kitchen,” where they sanitize items used to feed the sea lions. Trained volunteers prepare the food and feed the animals. For healthier sea lions, there are buckets of fat Alaska herring; sicker animals get a liquid mix of herring, fish oil and water. The center goes through 400 pounds of $1-a-pound herring a day trying to save the stranded pups.
The rise in ocean temperatures and scarcity of food isn’t just affecting sea lions—there’s a ripple effect up and down the chain when a “sentinel species” struggles.
“It’s very concerning to us,” Johnson says. The health of these apex predators “is a good indicator of the general health of the ocean. If sea lions can’t find enough food for themselves, what does it mean for other [sea creatures]?” he asks.
Additional reporting by Anne-Marie Harrison.