Biotoxin Research Targets Improved Seafood Safety

In the summer of 2016, the Department of Marine Resources closed a fishery in the Gulf of Maine and recalled shellfish across the state when it detected high levels of diarrhetic shellfish poison. However, these high levels may have actually been false positives.

Bigelow Laboratory for Ocean Sciences is working with the Maine Department of Marine Resources, the Food and Drug Administration, and NOAA to improve detection of toxins that affect seafood. The results will improve regulation of Maine’s fishing industry, and make Maine and the rest of the United States better prepared to address the public health problems that result when harmful algae poison shellfish.

“Until recently, diarrhetic shellfish poisoning just wasn’t considered a problem in the Northeast,” said Steve Archer, a senior research scientist and director of Bigelow Analytical Services. “There’s been an increase in harmful algal blooms around the U.S. coast, and toxic species appear to have spread to new regions.”

Following the fishery closure in 2016, NOAA secured the help of Bigelow Laboratory to assess the analytical kit that gave the positive results, as well as two other analytical kits for measuring diarrhetic shellfish poison.

If these commercially available kits hold up to proven laboratory techniques, they will progress through the approval processes for the Food and Drug Administration and the Interstate Shellfish Sanitation Commission. If approved, they will become available for use by shellfish growers, harvesters, and public health officials, who can use them to assess a batch of shellfish quickly and easily while out on the water or on the dock.

Harmful algal blooms occur when an overabundance of algae produces toxins, which can sicken animals from shellfish to humans. Shellfish eat by filtering large quantities of water, which can cause them to quickly internalize and concentrate toxins from harmful algal blooms. In addition to diarrhetic shellfish poisoning, harmful algal blooms can cause amnesic and paralytic shellfish poisoning – both of which are potentially fatal conditions.

“There’s some real complexity to this problem, and some really interesting science to be done,” Archer said. “For the health of consumers and the seafood industry, it’s important we get this right.”

Maine’s Department of Marine Resources contracts Bigelow Laboratory to help test about 3,000 shellfish samples for paralytic shellfish poison each year. The laboratory is the only facility in the country approved by the FDA to use an advanced chemical method to analyze samples for these toxins, which occur each summer in the Gulf of Maine and cause fishery closures.

Though paralytic shellfish poison has been recorded in the region for decades, amnesic and diarrhetic shellfish poisons are new. Occurrences of amnesic shellfish poisoning closed fisheries in Casco Bay as recently as December 2017. The increasing prevalence of harmful algal blooms is concerning for the seafood industry, scientists, and government officials alike.

The effort to assess commercial kits for the detection of diarrhetic shellfish poison is Bigelow Analytical Services’ first major research project into this illness. When large numbers of the algae Dinophysis blooms, the organism can produce toxins. Shellfish tainted by Dinophysis toxins causes stomach disturbances in the short term, and chronic exposure is potentially carcinogenic.

“The type of symptoms caused by diarrhetic shellfish poisoning aren’t often reported to public health officials, so I’m sure it’s a lot more prevalent than we think,” Archer said. “It’s important to learn as much as we can about this potentially serious condition.”

Currently, there are few methods approved in the United States for measuring the toxins that cause diarrhetic shellfish poisoning. This leaves state managers to decide on an individual basis how to monitor and regulate their fisheries. Archer is working with both industry and government partners to find a solution that will be helpful around the nation.

He hopes the kits will provide the Department of Marine Resources, shellfish harvesters, and other stakeholders a quick and inexpensive way to assess whether a shellfish sample is safe to eat. A positive result would send the catch to a lab for thorough chemical analysis.

“The kits will help to only close fisheries when it is necessary,” Archer said. “It is most important to keep people safe, but closures have financial repercussions as well. Consumers need to be confident in their seafood, and our fishermen need to be confident in toxin test results.”