An algal bloom near southern California beaches is causing sea lions to act unpredictably, according to a marine mammal expert. The toxic algal bloom is expected to become the “new normal,” as rising ocean temperatures contribute to an abundance of toxic algae. The algal bloom has led to sea lions exhibiting peculiar behavior, such as bobbing their heads side to side or extending them backward, foaming at the mouth, and in some cases, acting aggressively towards beachgoers. One woman even reported being bitten by a sea lion while on a 5K swim.
The cause of these unusual behaviors is a toxic algal bloom, described as the “worst outbreak” in Southern California yet. Fish, particularly sardines and anchovies, feed on the neurotoxin-producing algae and eventually poison large marine mammals with domoic acid when consumed. This toxin causes sea lions to behave strangely, coming to shore in crowded areas and experiencing symptoms of seizures. Many sea lions and dolphins have died after being poisoned by domoic acid.
The National Oceanic and Atmospheric Administration (NOAA) Fisheries reported more than 1,000 sick and dead marine mammals on the Channel Islands between June 8 and June 14. This surge in cases has overwhelmed marine mammal care centers and strained their resources. The Marine Mammal Care Center in Los Angeles has seen an increase in patients, particularly sea lions impacted by domoic acid. Currently, the facility has around 120 patients, 80 of which are sea lions.
The toxic algal bloom is not expected to be resolved anytime soon, as warming ocean temperatures contribute to the growth of algal blooms nationwide. The Environmental Working Group has identified warming ocean temperatures as the top contributing factor to algal blooms. In May, ocean temperatures reached record highs, creating an environment where algal blooms are bigger, more intense, and longer lasting. Marine experts believe this will become the “new normal.”
The timing of the toxic algal bloom is particularly challenging for sea lions, as a majority of them are born in June. The algae has affected the rookeries of California’s Channel Islands, which serve as breeding grounds for sea lions. Some sea lions are giving birth on Los Angeles beaches, and many of the pups are stillborn. Additionally, late June to early August is breeding season for California sea lions, and the toxic algae poses a risk to the males. The males, weighing anywhere from 300 to 700 pounds, may come ashore with domoic acid poisoning, potentially becoming a public safety issue.
There is also concern that the algal bloom may impact other pinniped species, such as harbor or elephant seals, if it comes close to shore. The potential risks to these species further complicate the situation. Marine mammal experts are urging the public to leave sea lions that come to shore alone and to notify lifeguards or nearby marine mammal agencies. Sometimes, sea lions are able to flush the acid out of their systems if they are given enough rest in a stress-free environment.
The Marine Mammal Care Center is accepting volunteers and donations to help support their efforts to care for the increasing number of sea lions impacted by the toxic algal bloom. The situation is closely monitored, with hopes that the bloom will not worsen or spread to affect other species. For now, the public is being advised to exercise caution and compassion when encountering sea lions on Southern California beaches.