Satellite tags trace sea lions re-entering the wild as rescuers brace for more strandings

As staff at Laguna Beach’s Pacific Marine Mammal Center prepare for another expected onslaught of malnourished sea lions washing ashore at Orange County beaches, center officials are just as interested in what happens to the animals once they return to the wild.

For the last three years, center staff placed satellite tags, comprised of battery-powered sensors, on the skin of sea lions released back into the ocean, hoping data collected will provide insight into their behavior.

Sea lion adults and pups along California’s coast encountered a difficult time the last few years as shifts in ocean currents and water temperatures resulted in record numbers of beached animals — typically, dehydrated pups.

The mammal center along Laguna Canyon Road handles all strandings throughout the county and rescued 538 sea lions last year, a record for the 40-year-old facility. As of Wednesday, 30 sea lions resided in the facility.

Experts speculate that warmer ocean temperatures are forcing sea lions’ normal food sources — squid, sardines, anchovies and rockfish — to seek deeper, colder water.

Adult sea lions either don’t find as much food, or expend more energy diving farther for fish and squid, said Sharon Melin, a wildlife biologist with the National Oceanic Atmospheric Administration Fisheries division. Sea lions can dive 500 to 600 feet, though it “costs them a lot of energy,” Melin said.

“Mothers aren’t finding as much food, so they are losing weight, thus not producing enough milk for sea lion pups,” Melin wrote in a follow-up email. “The sea lion pups, then, are malnourished, and they might strain themselves too much trying to find Mom, thus the pups end up washing ashore. The pups become malnourished and eventually attempt to find food on their own by leaving the rookeries [near the Channel Islands].

“But because they are too small to dive deep or travel far, are in poor condition, and are inexperienced hunters, they end up stranding on beaches emaciated.”

Underweight sea lions have entered the center weighing 20 pounds, five pounds below normal birth weight, Executive Director Keith Matassa said. Depending on the pups’ condition, center staff typically start the animals on all-liquid diets before graduating them to solid food. Once sea lions achieve a target weight around 75 pounds, the center releases them into the ocean, which is where the tags come in.

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Stranded again

Marine mammal center staff started placing tags — groups of batteries encased in clear, malleable plastic — on a random mix of five to six male and female sea lion pups each year beginning in 2013. Staff glue tags onto the animals with a low-heat epoxy.

The tags provide detailed information such as a sea lion’s location, duration and distance of dives, and water temperature. Sensors transmit signals, which include data contained in digital codes, to satellites, some of which NOAA monitors, when sea lions surface.

NOAA experts are still analyzing data gathered via satellites from the last three years, Matassa said, adding that he will look for whether sea lions are traveling to different places to find food and compare the routes with prior years.

“I want to know how my animals are doing out there,” Matassa said.

Each tag costs between $3,500 and $5,000, not counting an extra $10 to $12 per day for using the satellite. Battery life depends on how often information is uploaded to computers at the mammal center. Matassa programmed the sensors to upload information every other day, so a tag could provide data for three to six months.

“We sometimes get the satellite tags back, if we are lucky enough to have the animal drop it, say [on a La Jolla beach],” Matassa said. “But most of the time the sea lions keep them.”

The mammal center budgets one tag per year and writes grants to cover the remaining tags. McBeth Foundation, Kia Motors America and NOAA Fisheries have donated money to purchase tags in the past. The center is seeking funding for three tags this year, Matassa said.

Re-strandings, an occurrence when animals treated at mammal centers again wash ashore, spiked in 2015 compared to prior years.

“For most normal years we will see one re-strand a year that [was previously treated at PMMC] — our re-strand rate is very low,” Matassa wrote in a follow-up email.

Some sea lions treated at centers in Los Angeles and San Diego counties re-strand along the Orange County coast.

“However in 2015, 23 of the 44 re-stranded animals were PMMC animals,” Matassa said. “This leads us to more questions, but one possible obvious conclusion is that the conditions have worsened out in the environment.”

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A backup in Huntington

To help with the expected influx of patients, mammal center staff are working out details for a temporary sea lion triage center at the Wetlands & Wildlife Care Center in Huntington Beach for the second straight year.

“Huntington Beach has so many strandings, so busy with people,” Matassa said. “We can treat animals quicker, get them off the beach, make sure people are safe.”

Mammal center personnel and NOAA veterinarians will monitor sea lions’ vital signs, checking their breathing and taking blood samples, he said. If animal experts think the sea lions have adequate chances of survival, they will transfer the animals to the Laguna Beach facility. Animals deemed too sick are humanely euthanized, said Matassa, who hopes the triage center will open in two or three weeks.

Last year, 10 to 15 sea lion pups entered the triage center, with seven to nine eventually moving to the Laguna Beach facility.

Melin characterized sea lions’ plight as caused by a natural phenomenon, so there is only so much people can do.

Matassa understands he and his team can’t save every animal, but said “sea lions are making it if given the correct chance.”