The Marine Mammal Center in Marin County is on the front lines of a statewide response to a surge in sea lion pups turning up on California beaches emaciated and sometimes sick, at a time they still should be in the company of their mothers, nursing and learning to forage.
Already this year, the rehabilitation center in the Marin Headlands has received at least 108 California sea lions in need of care — mostly pups, but some juveniles and adults, as well, staff veterinarian Cara Field said Tuesday.
Even more were in line to arrive from triage centers farther south Wednesday, facility personnel said.
The marine mammal hospital usually takes in just a few California sea lion babies in January of a given year.
The most ever was last January, when there were 10, so “we’ve received a huge increase,” Field said.
The situation is similar across the network of marine mammal care facilities on the West Coast, many of them based in Southern California, closer to the Channel Islands sea lion rookery and other off-shore breeding grounds reaching into Baja.
Scores of malnourished pups, their big, dark eyes appearing even larger than usual in their thin faces, are being rehabilitated, taxing the nonprofit centers that take them in.
“Looking at the data over the past 10 years, this is the busiest January on record, as far as strandings go,” said Justin Viezbicke, California Stranding Network Coordinator for the National Marine Fisheries Service.
Statewide, there were just more than 250 strandings by the end of January, he said.
At the Pacific Marine Mammal Center in Laguna Beach, 38 sea lions are in care.
The Marine Mammal Care Center at Fort MacArthur in San Pedro had 87 sea lions, including 78 pups and eight sea lions of other ages, said Raymond Simanavicius, marketing and development manager.
Statewide, it’s the third year in a row that an unusual number of enfeebled young sea lions have been rescued from the California shoreline. The underlying cause remains a mystery.
“We’re getting twice the number we did in 2013, but we don’t know what the reason is,” Simanavicius said, referring to an episode in 2013 when the high number of sea lion fatalities and strandings was officially elevated to what the National Oceanic and Atmospheric Administration calls an “unusual mortality event.”
The Marin Headlands facility, whose usual response area includes a 600-mile stretch of coastline as far south as San Luis Obispo, is caring for animals recovered from its usual territory, but most are from the Santa Barbara area, which has just been overwhelmed, Field said. Though sea lions frequent the Sonoma Coast, no stranded pups have been reported there, likely because most of those finding themselves in trouble are too young and too weak to have made it that far north, she said.
The continued problems for the state’s sea lion population have puzzled scientists.
It’s possible the coastal waters, with an estimated sea lion population around 300,000, has reached its carrying capacity, Viezbicke said.
It’s also true that the ocean along the coastline is warmer this year, but whether that’s affected the sea lions’ prey or predators isn’t clear.
“At this point we can only speculate on what factor or factors may be contributing to this,” Viezbicke said.
Investigation into the 2013 event failed to turn up any common pathogen or toxin in those animals that died. Other evidence indicated the likely problem was that breeding females weren’t getting enough food to nourish their young adequately, possibly because of a shift in the traditional distribution of energy-rich anchovies and sardines, which spawned farther offshore in 2012 and 2013 than they have traditionally, according to the National Oceanic and Atmospheric Association’s fisheries division.
The birth rate among female sea lions also was low in 2013, perhaps half of normal, suggesting they weren’t getting sufficient nutrition to support gestation, NOAA Fisheries said.
More than 1,600 sea lions were stranded that year, the agency said. More than half survived and were released once they recovered.
But last year, again, high numbers of pups came ashore.
The Sausalito-area Marine Mammal Center, which has an average annual patient load of 600 animals, handled 711 mostly young sea lions in 2014, for a total of 1,030 animals in the year, facility spokeswoman Sarah van Schagen. Last year, it took until April for the center to reach the number of sea lions treated already this year.
Most sea lion pups are born in June, typically staying with their mothers for 10 or 11 months and becoming independent in May.
That so many are arriving at rehab centers early in the year now means they’re even younger than the bunch that came in last year and the year before, Field said.
Many of them should still be nursing and are in desperate need of hydration and nutrition. Where they should weigh 35 to 45 pounds by now, “they’re coming in probably between 15 to 25 pounds,” Field said. “So very underweight.”
Some have concurrent diseases, such as pneumonia, or opportunistic bacterial infections, but “they’re essentially starving,” she said.
Experts urge anyone who sees a stranded or injured marine mammal to leave it be, don’t go near it and don’t try to move it, which only causes stress.
Stranded animals from San Luis Obispo north can be reported to the Marine Mammal Center by calling 415-289-SEAL.
You can reach Staff Writer Mary Callahan at 521-5249 or firstname.lastname@example.org. On Twitter @MaryCallahanB.