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| California sea lion suffering from domoic acid poisoning. Photo: Jonathon Alcorn / Whale Rescue Team |
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Since March, marine mammal and seabird strandings and deaths off the Southern California coast have increased markedly. These incidences have been linked to the recent and dramatic increase of a naturally occurring toxin produced by algae.
Domoic acid, a naturally occurring toxin, is produced by microscopic algae and builds up in the tissue of fish and shellfish. Domoic acid poisoning results when high concentrations of the toxin are ingested by predator marine mammals, such as sea lions and dolphins along with seabirds, which feed on these fish and shellfish.
Domoic acid is a neurotoxin and poisoning can cause disorientation, seizures, and at high concentrations, even death. Although domoic acid has not been definitively linked to all the recent marine deaths, many of the dead animals have tested positive for the toxin.
In some cases, sea lions and seabirds can be treated for the poisoning. If you encounter a stranded animal, please contact the Marine Mammal Care Center (310-548-5677), the Bird Rescue Center (310-514-2573), or the Whale Rescue Team (800-39-WHALE). Please call the Los Angeles Deptartment of Beaches and Harbors (or similar agency for your county) if you encounter a dead animal at .
Seafood Consumption - State Issues Warning
It’s unusual for humans to be harmed from swimming in waters tainted with these algae, but consuming fish and shellfish with high concentrations of domoic acid can cause nausea, seizures and other health effects.
The State Department of Health Services recently issued an advisory against eating sport-harvested shellfish, anchovies, sardines, and both sports-harvested and commercially caught lobsters and crabs from Los Angeles, Orange, San Luis Obispo, Santa Barbara and Ventura counties. This advisory is in addition to the current quarantine on the sport-harvesting of mussels along the entire California coastline that took effect April 20, 2007.
Harmful algal blooms – a Trend?
Although plankton blooms are a natural occurrence, they can be exacerbated by human impacts such as overfishing, destruction of wetlands, and pollution that cause nutrient loading or alter the marine ecosystem. In recent years, harmful algal blooms, such as those that produce domoic acid along the California coast, have become extraordinarily prevalent and intensive.
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