Domoic acid scare temporarily shuts down lobster fishing along Orange County, LA coastline

High levels of domoic acid found within spiny lobsters in Southern California waters saw a temporary shutdown of fishing alongside certain areas of the Los Angeles coast, extending to Orange County. Photo courtesy of Wikicommons

Last month, the California Department of Fish and Wildlife issued a warning that commercial and recreational lobster fishing along portions of Southern California’s coast extending into Orange County would be delayed due to high levels of domoic acid found within lobsters. The high levels were specifically found in spiny lobsters, which are commonly fished both recreationally and for consumption purposes

Domoic acid is a type of neurotoxin produced during algae blooms by a type of algae known as pseudo-nitzschia australis. Depending on the level of exposure in humans, symptoms can range from nausea to diarrhea all the way up to seizures and permanent brain damage that could be fatal.

The neurotoxin often accumulates harmlessly in lobsters before being consumed by larger animals, which then suffer the effects of domoic acid poisoning. This leads to a process that Dr. Richelle Tanner, an environmental science & policy professor at Chapman University, describes as biomagnification.

“Since animals cannot break down domoic acid, it gets stored in tissues,” Tanner said. “When another animal eats the tissue, it gains the same amount of domoic acid. Since animals have to eat many of their prey to survive, each level of the food chain accumulates exponentially more domoic acid.”

This leads to top predators like humans and other sea creatures being exposed to far larger amounts of domoic acid when consuming affected animals, leading to the aforementioned potentially fatal side effects. Notably, an algae bloom containing domoic acid occurred earlier this year, which saw the deaths of thousands of marine mammals, including sea lions. There are other effects resulting from a pseudo-nitzschia bloom, as explained by Chapman life and environmental sciences professor Dr. Bill Wright.

“Pseudo-nitzschia blooms really mess with other phytoplankton species and likely impact the primary consumers like copepods and krill,” Wright said. “Not because they get sick, but because they can’t really grow without their usual planktonic soup (large diatoms, flagellates, etc.).”

While fishing was halted for commercial purposes, some recreational fishing did continue to occur under a “catch and release” policy. The warning from officials came right around the time where large amounts of spiny lobster recreational fishing began, though some participants expressed that they would simply fish in areas beyond the advisory zone set up along the Los Angeles and Orange County coastline.

While it is currently unknown if the algae bloom from the summer was the cause of the current rise in domoic acid levels in spiny lobsters, the causes of the blooms themselves are not entirely natural.

“As temperatures rise, as they have been from our local heat waves, harmful algal blooms become more commonplace,” Tanner said. “Additionally, if there are increased levels of limiting nutrients such as phosphorus and nitrogen because of our agricultural and urban runoff, we can also see more frequent harmful algal blooms.”

Ultimately, the advisory was taken away around Oct. 16 as the Department of Fish and Wildlife determined, after several more tests, that the levels of domoic acid within lobsters had gone down to a safe level for consumption, federally mandated at 20 parts per million in spiny lobster viscera.

Nevertheless, an air of caution remains as people consuming spiny lobster are still advised to follow certain practices to limit possible exposure to domoic acid.

“It is important to listen to local fish and wildlife officials who regularly test fisheries species for acceptable levels of domoic acid and other harmful toxins that might be present because of biomagnification,” Tanner said. “It is also important to remember that the causes of harmful algal blooms, especially when they are so frequent, are human-induced by our over-reliance on fertilizer and our contributions to warming via the burning of fossil fuels.”