SAUSALITO, Calif. (KTVU) - California sea lions are world famous and well-loved at San Francisco's Pier 39, but the Marine Mammal Center in Sausalito says an alarming number of poisoned sea lions are being brought in for treatment from the central coast.
Scientists say the cause is domoic acid, a neurotoxin produced by a type of algae Pseudo-nitzschia that has become widespread in warm waters along the west coast.
"This is more pronounced than we've seen in the past few years," said Michael Milstein, a spokesman for NOAA Fisheries West Coast Region, "It's actually a continuation of a trend we started seeing earlier in the summer further south down around Los Angeles. We started getting reports of sea lions, dolphins, birds, some pelicans as well, showing symptoms of domoic acid poisoning."
The Marine Mammal Center staff say they had 70 cases of domoic acid poisoning in 2016.
In just the past six weeks, 73 poisoned animals have come into the center. That makes a total of 89 domoic acid cases so far this year.
Video taken Monday at the Marine Mammal Center shows one sea lion suffering from the neurotoxin, which can lead to lethargy, seizures, and even death.
The toxin attacks the animals brain causing dark spots where the acid has eaten away the tissue.
It's the same toxin that shut down the 2015 Dungeness crab season, when high levels of domoic acid were found in animals as far north as Washington State.
Scientists say they'll be watching closely to see if water temperatures cool and eliminate the algae in time for the fall fishing season.
Tourists also hope the sea lions at Pier 39 remain safe.
"It's amazing there are so many," said Lily White, a tourist from St. Petersburg, Florida.
"This is so great because normally we have to go to the zoo to see them and then here they're all right here. It's just fantastic. My kids love it," said Laura Mullen of Chicago.
"It's really nice to see all of them in their natural habitat," said Taylor Bell, visiting from Chicago
"It's in the fish obviously that the sea lions are eating. There's no sign of it yet in Dungeness Crab and I should mention the states are very vigilent about testing," said Milstein.
The Central and Northern California Ocean Observing System generates computer models with an estimation of where the algae is blooming along the west coast.
Already the California Department of Health has warned people to avoid eating shellfish from the Channel Islands near Santa Barbara because of domoic acid levels.
As for the sick sea lions, the Marine Mammal Center has been able to treat and release about half of them back into the ocean.