ELLSWORTH — Nobody wants to eat bad shellfish.
At the least, consuming a clam or mussel contaminated by red tide can lead to a badly upset stomach. At its worst, a case of parasitic shellfish poisoning (PSP) caused by a toxin in the algae that produce red tide can be fatal.
The same may be true of shellfish harvested from waters with high levels of E. coli — fecal coliform bacteria — that indicates the presence of sewage in the water. Diseases such as Norwalk virus, Salmonella, E. coli and hepatitis A virus, come from the contamination of water by sewage.
For many years, the Department of Marine Resources has monitored the state’s waters for bacterial contamination and tracked the mostly warm weather algal blooms that cause red tide. At hundreds of sites along the coast, volunteers and DMR staff, collected water samples and tested them for the presence of Alexandrium, the plankton that produces the toxin that causes PSP.
Alexandrium regularly forms massive blooms along the northeastern coasts of the United States and Canada, resulting in enormous economic losses from shellfish harvesting closures as well as public health concerns.
Over the past two years, according to Kohl Kanwit, director of DMR’s Bureau of Public Health, monitors have been on the lookout for the presence of another marine organism, a phytoplankton known as Pseudo-nitzschia, which produces domoic acid, the neurotoxin responsible for the neurological disorder amnesic shellfish poisoning.
“The phytoplankton monitoring program has matured over the last two years,” Kanwit said recently. “Before that it was reactionary. Now we’ve set up the program so it can be proactive.”
That is largely a consequence of DMR turning to the privately owned Bigelow Laboratory for Ocean Sciences in East Boothbay for testing water quality samples. The partnership with Bigelow, “gives us a more advanced testing capability,” Kanwit said. “It broadens our ability to test for other toxins.”
That’s good news for the Maine shellfish industry.
Although there have been no documented cases of ASP in Maine, in 1987, 250 people in Canada were sickened, and four victims died, after consuming mussels from Prince Edward that contained the toxin.
“There have been several incidents in Canada, and that’s just around the corner,” Kanwit said.
According to scientists at the Woods Hole Oceanographic Institution, ASP can be life-threatening and can produce both gastrointestinal and neurological effects.
Nausea, vomiting, abdominal cramps and diarrhea usually develop within 24 hours of the consumption of toxic shellfish. In severe cases, neurological symptoms including dizziness, headache, seizures, disorientation, short-term memory loss, respiratory difficulty and coma will occur within 48 hours.
In the Gulf of Maine, both mussels and scallops could become tainted by domoic acid. If that were to happen, the economic consequences to the Maine fishing industry could be dire.
A massive algae bloom caused resulting from waters warmed by a massive El Niño event in the Pacific led California authorities to suspend the state’s Dungeness crab fishery, slated to begin Nov. 15, indefinitely. Some crab samples tested by the California Department of Fish and Wildlife contained domoic acid at levels of 190 parts per million, more than nine times the accepted safe limit of 20 ppm.
Authorities in Oregon, where crab season doesn’t begin until Dec. 1 are also monitoring domoic acid levels in crabs taken in waters off its coast.
The California crab fishery is estimated to be worth some $60 million annually.
Although scientists have known since 1959 that domoic acid could be found in marine algae, it wasn’t until the 1987 incident that it was identified as a potential source of shellfish poisoning.
In 1961, hundreds of disoriented birds crashed into buildings and to the ground in the coastal California town of Capitola. Scientists now believe the cause was domoic acid poisoning. Movie historians say the event inspired Alfred Hitchcock to make his horror movie “The Birds.”