A growing number of California sea lions have been showing clinical signs of domoic acid poisoning since June 7, the Channel Island Marine and Wildlife Institute announced Friday.
It is typical this time of the year for the institute to see a few sick sea lions, a couple per week,
and “Every three to five years you’ll see a higher number,” said Executive Director and Chief Veterinarian Sam Dover.
But this year, the number of reports is unusually large, three to 10 per week. That is one of the highest rates in a long time and it doesn’t appear to be subsiding as usual, Dr. Dover said.
“We saw a trickle in April and May, but then last week there was a deluge,” he said.
Since June 7 there have been 32 reports of sick sea lions, Dr. Dover said.
“They’re pretty much everywhere,” he said.
The institute works within 155 miles of the coast in Santa Barbara and Ventura counties, and has found random sample groups of affected sea lions up and down the area’s beaches.
Domoic acid is produced by pseudo-nitzschia algae, which naturally occurs during algae blooms in the spring and fall. It remains harmless until colonies of toxic microscopic algae grow out of control, resulting in a harmful algae bloom that is then consumed by bottom feeders, such as anchovies, shrimp and mussels.
The domoic acid accumulates without ill effect in the smaller animals, but when they are consumed by larger mammals such as sea lions, the toxic prey can cause up to 72 hours of severe illness.
The effect of domoic acid on sea lions depends on the amount of domoic acid they consume, according to an institute news release.
“Presentation of Domoic Acid includes lethargy, disorientation (unaware of human/animal presence, moving around aimlessly), head bobbing and weaving, muscle spasms, seizures, foaming at the mouth, eye bulging, unresponsiveness and the inability to move out of rising tide,” the release reads.
Most reports describe sea lions suffering from seizures. The toxin targets the central nervous system and brain, causing hippocampal degeneration, in the part of the brain responsible for spatial memory and navigation.
“It affects the part of the brain that is a mental map,” said Dr. Dover.
That impacts the long-term survival of the animal, he said. Even though a sea lion might not be in immediate danger, too much degeneration and the sea lion loses track of food and mating sites. In severe cases the toxins can cause death. The institute sees about a 50 percent chance of recovery.
Other areas have not been impacted as heavily as Venture and Santa Barbara counties. That has to do in part with population density, said Mr. Dover. There are more witnesses to report ailing sea lions in Santa Barbara than on other parts of the coast.
The cause of the high level of reports has not been identified.
“We have some suspicions,” said Dr. Dover.
But the institute suspects the combination of urban coastline and higher rainfall over the last year has resulted in nutrients from the hills draining into the ocean, acting as fertilizer for algae.
Locals are still able to enjoy the area’s beaches, but the institute warns against approaching any sea lions, even if they are docile.
A sick sea lion suffering from seizures may allow beachgoers to approach, unlike a healthy adult, but “They can snap out of it real quick. They get up to 200 to 300 pounds. You don’t want to get bitten by an adult female sea lion,” Dr. Dover said.
If a sick sea lion is spotted, people should not touch it. Instead,, observe the animal from a minimum of 50 feet and note its physical characteristics and condition, determine its exact location, and call the CIMWI Rescue Hotline at 805-567-1505.
Because transporting a sea lion for care is stressful and may affect the immediate survival of the animal, the institute, when possible, leaves sea lions suspected of having domoic acid poisoning on the beach in a safety perimeter, giving the animal space and time to work through the acute phase of the toxin.
CIMWI is an all-volunteer organization with a team of a little over 100. In May, the team rescued 62 starving sea lion pups, which will be in rehabilitation for about three months. This, combined with the domoic acid incidents, has put the institute in a crisis situation.
“It’s been a drain on our resources,” said Dr. Dover.
For more information on Domoic Acid, visit http://cimwi.org/domoic-acid/.