Dozens of sick sea lions have been turning up along California's Central Coast, as marine animal rescuers field hundreds of calls daily.

The Marine Mammal Center has rescued about 30 California sea lions sick from domoic acid poisoning in Monterey County and southern Santa Cruz Counties over the past week, said Giancarlo Rulli, a spokesperson for the nonprofit. Rulli said that count also does not include additional rescues in San Mateo, San Francisco, Marin and Sonoma counties. There have also been a handful of northern fur seals affected.

The spike in sick animals has also triggered a surge in reports from the public.

"Our dispatch team is receiving anywhere from 300 to more than 600 calls to our hotline every single day, which is an incredibly high volume of calls," Rulli said.

Typically, in an average year across the center's 600-mile California response range from San Luis Obispo County to Mendocino County, they will see from about 75 to 90 cases of domoic acid poisonings in sea lions. "We're already over 100 cases at this point as we turn the page into the month of September, and there's no real clear indicator as to how long this current situation may last," Rulli said.

FOX Weather also reported that more than 100 sea lions have been rescued since the beginning of the year, with the majority since July 1.

What is domoic acid poisoning?

Domoic acid is an algal toxin that is naturally occurring in the marine ecosystem, according to Rulli. "We're talking here on the S. West Coast in the Pacific, and this algal toxin is a neurotoxin that basically works its way up the food chain," Rulli said.

The toxin accumulates in fish and shellfish, which are not directly impacted, Rulli said. But when large marine mammals, such as California sea lions, eat a high concentration of those forage fish, the algal toxin can result in a range of neurological symptoms including lethargy, disorientation, unpredictable behavior, twitching, tremors and seizures.

In some cases, the animals can suffer permanent brain damage in the form of lesions, as well as heart damage, according to the Marine Mammal Center as reported by FOX Weather.

Outbreaks becoming less seasonal and more intense

The Marine Mammal Center first documented domoic acid poisoning in California sea lions in 1998. Since then, outbreaks have become less seasonal and more intense, Rulli said.

"Because domoic acid is naturally occurring, the challenge is understanding why and when conditions align to produce increasingly significant toxic events," the Marine Mammal Center said, as quoted by FOX Weather.

Domoic acid poisoning typically occurs during certain seasonal conditions, such as cold-water years when coastal upwelling and offshore winds bring nutrient-rich water to the surface, supporting blooms of the algae Pseudo-nitzschia, which produces domoic acid.

Rescue and treatment efforts

Sea lions weigh anywhere from 100 to more than 300 pounds. Rescue requires four to six trained volunteer responders with a 50-to-100-pound metal carrier, Rulli said. Veterinary staff provide bagged fluids, anti-seizure medication, and long-term treatment.

Breakthrough seizures can be a sign of chronic domoic acid poisoning. Acute poisoning occurs after recent high consumption; chronic poisoning occurs over multiple exposures.

California sea lions are called "true sentinels for ocean health," Rulli said. The California Department of Public Health is alerted to test marine organisms.

Rulli urged beachgoers to keep at least 150 feet from distressed animals. The Marine Mammal Center's hotline number is 415-289-7325. He noted there are many repeat calls for the same individual.