Wildlife experts and rescue organizations are sounding the alarm over a growing wave of sick and dead sea lions and seabirds washing ashore along San Mateo County beaches, with Half Moon Bay emerging as a primary hotspot.
Beachgoers like local resident James have noticed the stark increase firsthand: “It’s not just me, everybody is noticing, this year a lot more than usual sea lions and birds showing up dead on the beach.”
Marine experts attribute the sea lion deaths primarily to domoic acid poisoning, a naturally occurring neurotoxin produced by blooming algae. The toxin is absorbed by small fish and subsequently ingested by marine mammals.
“It’s a naturally occurring toxin, it can thrive in both warm water conditions as well as cold water conditions,” said Giancarlo Rulli, a spokesperson for the Marine Mammal Center. While overall response calls have declined elsewhere, Rulli noted that “we’ve seen a decline in the number of calls and responses since then except for San Mateo County; Half Moon Bay has been a primary hot spot the last few weeks.”
The crisis extends beyond marine mammals. Since mid-August, International Bird Rescue has taken in approximately 300 sick birds, primarily common murres, exhibiting high mortality rates.
“Since early September we have been seeing or hearing reports and getting large numbers of common murres only, so it seems to be a large mortality rate,” said JD Bergeron, CEO of International Bird Rescue.
Biologists believe the birds are starving because rising ocean temperatures have forced their typical prey deeper or into entirely different areas.
“If the birds are going to traditional hunting grounds where there are normally fish and the water is a lot warmer, the fish will either be lower in the water… or just be elsewhere,” Bergeron explained.
Chief Meteorologist Jeff Ranieri noted that the crisis is driven by a powerful one-two punch: a marine heat wave off the California coast combining with El Niño conditions pushing warmer waters toward the state. With El Niño expected to ramp up in coming months, scientists warn the situation remains highly volatile.
“There is this collective of unknown moving forward, but what we can prepare is that things will continue to be more unpredictable moving forward,” Rulli said.
Wildlife officials urge the public to keep a safe distance from stranded or dead marine animals, keep pets away, and report sick wildlife immediately to organizations such as the Marine Mammal Center or International Bird Rescue.
