Abnormally high numbers of malnourished California sea lion pups continue to wash up onto California beaches, with already nearly 1000 taken in statewide for treatment this year.
Despite early preparations for the high number of potential strandings, rescue facilities are becoming overwhelmed with the volume of starving young pups.
“There are so many calls that we’re getting, we just can’t respond to them all,” said Justin Viezbicke, a stranding coordinator for the National Oceanic and Atmospheric Administration. “The reality is that we can’t get to all of these animals. We’ll do our best, but the capacity to take all of the animals that are coming ashore just isn’t there.”
In 2013, record high numbers of sea lion strandings occurred in California, leading NOAA Fisheries to declare an “unusual mortality event” for the species. Though it is too early for the agency to declare another UME for 2015, January of this year saw five times the average and twice the number of strandings that occurred during the first month of 2013.
California Sea Lion Pup and Yearling Strandings for California
Data from NOAA Fisheries
In San Pedro, rescue workers at the Marine Mammal Care Center said more than 100 sea lions were being treated at the facility. Typically, the center would have 12-to-20 of the animals by this time of year.
David Bard, operations director for the Marine Mammal Care Center, said that the center had received multiple grants and been able to increase intern staffing, but the facility is still unable to keep up with the need.
“Despite those increases and the two new enclosures we installed, we’re still taxing our resources just from the sheer numbers of the response,” Bard said.
Bard said the center is hoping to take on 56 additional volunteers to assist with daily tasks such as washing dishes and cleaning kennels, thus freeing up trained experts to treat more sea lions. He said the center is also welcoming monetary donations, supplies and gas cards to aid in rescue efforts.
Scientists are still unclear on what is causing the strandings, but they suspect that persistent warmer-than-average ocean temperatures are causing prey fish to move from hunting grounds that nursing mothers know. The increased time spent foraging may be increasing fasting times for pups, thus causing them to wean too early.
Early season nursing appears to have been poor. Scientists who monitor the breeding rookeries of sea lions found that over a four-month period, pups gained an average of 1.2 kilograms in weight.
“That’s the lowest growth rate we’ve ever observed,” said Sharon Melin, wildlife biologist with the National Marine Mammal Laboratory.
Despite the record number of strandings and likely high mortalities, scientists said the California sea lion population is stable, with a total size of about 300,000 animals.
Scientists said the warmer ocean temperatures off the California coast are due to normal variations in wind patterns and not likely due to global warming because of their localized effects.
“It’s the kind of thing that has happened in different ways in the past. It’s likely to continue happening in the future,” said Nate Mantua, a NOAA climatologist. “Scientifically, it’s really interesting, and I don’t see it as something we should be really alarmed about.”
Bard said that beachgoers who encounter sea lion pups should not approach or try to feed the animals but should contact authorities.
"Trying to feed a marine mammal something that's not in its regular diet is not only not helping the animal, but it could be detrimental overall to its health," he said.