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, 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 on the early warning signs they picked up after the most recent pupping season began last summer.
Pups in the Channel Island rookeries, about three hours north of San Diego, 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, 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.
“They’ll come into rehab and are doing fine, and then they’ll just crash and go hypothermic and hypoglycemic,” Schmitt said.
– U-T San Diego