As ocean temps rise, so does risk for shellfish poisoning

It’s not unusual for people to have shellfish allergies, but even non-allergic people can get sick from eating shellfish, thanks to contamination that occurs when the filter-feeding sea creatures take in toxins in warm ocean waters. Now, research is showing that the algae and bacteria that cause these toxins are becoming more prevalent as sea temperatures rise.

The three ‘SPs

The three most well-known types of shellfish poisoning are amnesic shellfish poisoning (ASP), diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP). As you might guess from those names, symptoms of these illnesses range from uncomfortable to very serious.

These illnesses are caused by marine biotoxins — like domoic acid, which causes ASP — which are produced by algal blooms. Shellfish then consume the toxins while filter feeding. The toxins remain in the shellfish systems, without actually affecting them. A contaminated shellfish will appear normal without scientific testing.

Algal blooms are most common in warm, summer months, and as ocean temperatures rise around the globe, more coastal regions are seeing an increase in algal blooms. One study from the Oregon Department of Fish and Wildlife looked at temperatures in the Pacific Ocean in previous years. The findings showed that the five warmest years were also the years with the highest detected levels of domoic acid.

“The biggest takeaway is that the ocean temperatures are changing,” said Matthew Hunter, a researcher on the study. “That has the potential for more frequent and more extreme harmful algal blooms that have significant implications for not only fisheries but also natural resources and human health.”

More algae means a higher risk of human illness, and that the food industry needs to be on higher alert, carefully testing for the presence of toxins in its shellfish.

“What was once considered a summertime matter is now being considered a year-round issue,” says the Washington Department of Health on its website.

Neogen offers rapid tests to detect shellfish toxins and other seafood concerns. Click here for more information.

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