By Rita Robinson | LB Indy
To exacerbate the deluge of emaciated sea lion pups at the Pacific Marine Mammal Center, adult sea lion females with chronic and often-fatal domoic acid poisoning are also being rescued along the local coastline.
Last week, 21 starving young sea lions were shuttled by emergency animal services to the marine mammal emergency center in Laguna Canyon. The center is now caring for 151 sick sea lions, according to a spokesperson, which is the highest number of patients treated there in the center’s 42-year history. The overwhelming number is taxing supplies and staff.
From Santa Barbara to the Mexican border, 1,293 sea lion pups in extremely weak condition have been rescued since January and taken to seven mammal care centers throughout the state, Sarah Wilkin, stranding coordinator at the Long Beach office for the National Oceanic and Atmospheric Association, reported Wednesday. The historic annual average is 236, which makes this year’s three-and-a-half month rescue figure five times greater than the historic average, she said.
The main cause being investigated is lack of food, Wilkin said. In the last few weeks, there’s been a slight slow-down in rescues, attributed to fewer rescue calls due to poor weather and more typical seasonal rescues of stranded young sea lions in slightly better shape, she said. The intake of severely dehydrated and starving pups is still above average, she said.
This week, three sea lion pups of several that have been returned to the ocean were the first to be determined as “non-releasable” after being rescued again, said Wilkin. “Those three animals that were released and restranded relatively quickly in very poor body condition presumably had not been able to successfully forage on their own at all,” she said. Because they’re unable to survive in the wild, Wilkin said they will be placed in either a zoo or aquarium. Two other pups that were released with satellite tags, appear to be foraging on their own, she added while other restranded pups are being evaluated for their ability to survive in the ocean.
Although no definitive conclusions have yet been made, Michele Hunter, director of animal care at PMMC, said the domoic acid toxicosis in the adult sea lion females, which causes seizures and brain damage, does not apply to the symptoms observed in the sick sea lion pups.
“It’s been typical that adult females are brought in with demoic acid poisoning due to the toxic algae bloom that occurs in the spring,” she said. Necropsies of pups that died have not revealed any other cause of the epidemic other than severe emaciation, said Hunter.
The pups, normally weaned in April, are still in the suckling stage and suffering from starvation and dehydration due to lack of food from nursing mothers and their own inexperienced fishing exploits. Scientists are investigating the reason for the lack of food, said Wilkin. Samplings are now being conducted “to rule out” other conditions such as infectious diseases, toxins and pollutants. No results are available yet, she said.
The food shortage for the sea lions could be due to a lack of upwelling of cold water to the ocean’s surface as the result of wind changes. A lack of upwelling causes prey fish to stay in colder, deeper water and farther away from predators, such as adult, nursing female sea lions. Wilkin said the high number of young sick sea mammals would be understandable under El Nino conditions but presents a mystery since noticeable wind shifts do not currently exist.
A similar extreme stranding event occurred in 2009, she said, when prevailing onshore winds did not blow as strongly as they usually do, causing a lack of upwelling, which created food foraging difficulty for sea lions.
No conclusions have yet been made about the cause of the epidemic. Under federal funding due to the event’s designation as an “unusual mortality event,” scientists are now coordinating research and findings.
In order to assist the Laguna center’s efforts, two shipping containers will be temporarily allowed on nearby city property to store the extra food, blankets, and other supplies donated to the PMMC.
The first case of demoic acid poisoning, which affects the brain and causes seizures that can lead to the animal’s death, was discovered in March 1998 by the The Marine Mammal Center in Sausalito. The cause, according to research directed by center veterinarian Frances Gulland, is related to human pollutants in the ocean. The pollutants usually create the toxic algae bloom when weather and waters warm up in the spring. Cases of poisoned marine mammals have resulted in screenings of shellfish and other seafood for fatal biotoxins to protect human health.
Known as “red tide,” domoic acid is a neurotoxin produced by phytoplankton, specifically a microscopic diatom, that “prey fish,” including sardines, anchovies and shellfish, feed on. The prey fish are then contaminated with the poisoning, which is passed on to their predators, including sea lions as well as humans, and can cause severe seizures and other central nervous system disorders, according to the TMMC.
Sick and stranded marine mammals are sentinels of potentially dangerous environmental changes that could affect human health, TMMC reports.
TMMC, which covers coastline from San Luis Obispo to Fort Bragg, has doubled its intake of sick sea animals over last year, largely due to taking in 45 sick sea lion patients trucked in from capacity-filled rescue centers in Southern California, said spokesman Jim Oswald. There are more sick sea lions in Southern California, he explained, because their rookeries are in the Channel Islands. Forty-five percent of the pups born last June have died, higher than the normal attrition rate of one-third, according to figures released by the National Marine Fisheries Service in Seattle.
Next week, TMMC is hosting a global conference of scientists to discuss ocean health, and sea lion pup starvation and dehydration will be discussed. An increase in reports of diseases in marine organisms is raising concern that ocean health is deteriorating, says a conference summary at an aquatic animal medicine site, IAAAM.org. “Humans are having dramatic effects on aquatic animal health, both directly as a consequence of shipping, fishing and energy exploitation, and indirectly via effects on climate, prey and pathogen distribution and habitat alteration and pollution,” according to information about the conference. The conference will focus on human impacts on marine animal health worldwide with leaders in the field from each continent.
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