Trend follows more severe sea lion starvation event that hit La Jolla coast two years ago
Wave after wave of starving sea lion pups are drifting ashore in what officials said could be an outbreak of strandings similar to that seen in 2013 along California’s coastline.
The warmer waters flushed in by El Niño, a periodic marine and atmospheric phenomenon, might be shifting the animals’ food supply. That could be leaving mother sea lions malnourished and forcing pups to strike out on their own too soon, experts said.
For the past decade, sea lion strandings have averaged about 250 during the key period of monitoring between each January and April, said Justin Viezbicke with the National Oceanic and Atmospheric Administration’s fisheries service.
Since Jan. 1 of this year, however, marine mammal centers along the state have already received 150 of the animals.
In 2013, about 1,350 sea lions — more than five times the annual average — stranded on California beaches in what officials classified as an “unusual mortality event.”
Scientists fear a similar toll this year, based not only on what they have encountered in recent weeks but also the early warning signs they picked up after the most recent pupping season began last summer.
Pups in the Channel Island rookeries were about 19 percent below average weight in September, said Sharon Melin, a wildlife biologist with NOAA fisheries. Nearly one out of three pups born last summer have died — about 12 percent higher than the normal mortality rate.
“All of the (rescue and rehabilitation) facilities are preparing for the worst and hoping for the best,” said Viezbicke, who is also coordinator of the California Stranding Network. “They’re getting staffing ready, looking at transferring animals if facilities are full, sharing staffing and resources and getting everybody ready to respond.”
SeaWorld San Diego started seeing strandings in December, instead of the typical February. The marine park has taken in 55 sick and starving sea lion pups this season.
“A lot of these guys are coming in malnourished and dehydrated because they’ve been weaned too early from their moms,” said Todd Schmitt, SeaWorld’s senior veterinarian.
Some of the pups arrive barely over their birth weight of 18 to 22 pounds, he said. Many are riddled with parasites or have respiratory infections, digestive maladies or a strain of pox. Some start to rally but then decline unexpectedly.
As a group of recovering pups devoured fish the staff distributed at SeaWorld’s rehabilitation facility Tuesday morning, a 30-pound sea lion slumped against the side of his enclosure, a fish dangling from his mouth.
Too sick to eat, the shivering pup finally spit out the morsel — and soon a snowy egret came and snapped it up. The pup, rescued from Oceanside on Jan. 18, had regained a couple of pounds since but was quickly losing ground on Tuesday.
“They’ll come into rehab and are doing fine, and then they’ll just crash and go hypothermic and hypoglycemic,” Schmitt said.
SeaWorld workers quickly whisked the pup away for emergency treatment. Veterinary technicians huddled around the animal to inject subcutaneous fluid laced with dextrose and electrolytes to restore his blood sugar levels. They placed him under a heat lamp and put hot pads under his flippers to warm his body, which had slipped from a normal temperature of about 98 degrees Fahrenheit to just 87.
About a dozen SeaWorld employees are on rotation in the rehabilitation center to care for the sea lions, said Jody Westberg, stranded animal coordinator for the park.
As rescued pups come in, staffers weigh them, take other measurements, perform blood tests and administer subcutaneous fluid for rehydration. Once the animals are stabilized, they can graduate to formula — a blend of fish, milk and vitamins — and then eventually eat whole fish.
Each pup typically requires about six weeks of care, at a cost of several thousand dollars, before it gains enough body weight to be released into the ocean again, Schmitt said.
It’s a routine that SeaWorld may repeat hundreds of times this season.
Although they’re not certain why the sea lions are faring worse than usual, marine officials think the warmer waters may make prey fish scarce. The sardines, anchovies and other small fish that form the diet of sea lions may be migrating north, forcing mothers to spend more days hunting away from their pups, said Melin at NOAA. Without their mother’s milk during that time, the youngsters can become underweight or even emaciated. Disease may also play a role, Melin said.
Although strandings and deaths are part of nature’s equation, Schmitt said rehabilitation centers can boost pups’ odds of survival.
“It’s really being a good steward of the ocean and giving them a second chance,” he said.