Algae bloom has caused a spike in domoic acid, a neurotoxin that is passed from fish to their predators.
Domoic acid poisoning is at least partly to blame for the spate of sick marine life from Santa Barbara to San Diego, according to reports.
Fish eat algae then pass on the naturally occurring neurotoxin to its predators, causing seizures, brain damage and, in some cases, death.
Extremely large, dangerous algae blooms which kill fish, pets and is very nasty for humans have been reported across North America recently and are increasing from Canada to Southern California.
Although algae blooms apppear every year in US waters, scientists claim they are on the increase.
People who come in contact with the algae blooms - or ingest water contaminated by the algae - may experience skin irritation, a rash, a sore throat, red eyes, swollen lips, fever, nausea, vomiting and diarrhea.