New Parasite Discovered to be Infecting Cod in Gulf of Maine

Gulf of Maine

BOSTON – September 1, 2010 A team of scientists led by Massachusetts Institute of Technology Sea Grant (MITSG) College Program today announced the discovery of a new, as-yet unidentified parasite that is infecting cod in the waters of the Gulf of Maine.

The parasite is a species of acanthocephalan, or spiny-headed worm. Heavily infected fish sicken and die, making the parasite a serious threat to cod populations.

The parasite was first discovered by local commercial cod fishermen, who began noticing the easily-seen parasite as soon as the Gulf of Maine multispecies fishery opened in spring 2010. “It would have been hard to miss, “said Jack Spade, commercial fisherman and member of the Cape Cod Commercial Hook Fisherman’s Association (CCCHA). “Those worms are bright yellow.”

MITSG is working with the local fishing community to map the prevalence and severity of infection of the new parasite. Several members of the CCCHA as well as fishermen in Gloucester and other Gulf of Maine ports are providing valuable data to researchers. If left unchecked, the parasite could severely curtail this year’s codfish catch, further damaging an already weakened commercial fishing sector. “We know we have a big role to play here,” said Mr. Spade, “and look forward to working with the researchers to get to the bottom of this.”

MITSC is collaborating with Environmental Protection Agency (EPA) parasitologists to identify the species and its native range and life cycle. Although unlikely, it is theoretically possible for humans who eat the infected cod to ingest the parasite and become infected themselves. “We do believe at this point that infection in humans is unlikely,” said EPA spokesperson Sharon McCoy. “The parasite is easily seen and it also lives in the body cavity of the fish, not in the muscle tissue.”

However, the Massachusetts Department of Public Health is looking into whether any sort of restrictions are called for. As with any potentially threat to the food supply, the DPH recommends limiting exposure to possibly infected cod, particularly for young children, those with weakened immune systems and frail elderly.  For the latest updates, check the Massachusetts DPH website. New Hampshire and Maine are not considering any public health actions at this time.

Scientists at the Woods Hole Oceanographic Institution are also involved in the effort to identify the parasite. Population modelers at the Woods Hole Center for Oceans and Human Health (WHCOHH) are developing projections for how the parasite may affect cod stocks in the near future. To protect consumers, and the livelihoods of fishermen from Maine to Massachusetts, researchers hope to be able to forecast where and when the parasite will next appear. And their work may also lead to answers as to what and why.

Scientists Dennis O’Leary and Zhuchen Le have developed a mathematical model of the parasite’s dynamics —a series of equations that captures the physical and biological factors involved in the movements of the parasite through the cod stocks in the Gulf of Maine.

GoM model 2

O’Leary and Le entered a range of factors into their model: the speeds and directions of ocean currents, water temperature and salinity, winds, surface heat exchanges, tides, river runoff, and the distribution and behavior of the parasite in the water. They also incorporated other computer models that describe waterborne nutrients, solar radiation, and large-scale motions in the North Atlantic Ocean.

“The beauty of a numerical model,” said O’Leary, “is that it can be used to investigate extraordinarily complex systems by posing the problem in terms of a few guiding principles expressed as mathematical equations.”

WHCOHH researchers regularly share their field observations and models with more than 80 coastal resource and fisheries managers in six states as well as federal entities like NOAA, the Environmental Protection Agency, and the Food and Drug Administration.

“Managers believe that a regional-scale, seasonal outlook can be useful in preparing for contingencies, ” said Dr. Judith Pederson of MITSG. ” This advanced warning, along with updates closer to and during the cod fishing season, can help state agencies prepare for monitoring and assessing public health risks, and also give fishermen the opportunity to shift the timing of their harvest.”  Area restaurants may also benefit from advance warnings by making contingency plans for seafood supplies.

WHCOHH is funded by the National Science Foundation and the National Institute for Envrionmental Health Sciences. Additional research is provided by the Canadian Department of Fisheries and Oceans, Maine Department of Marine Resources, New Hampshire Department of Environmental Services, Massachusetts Division of Marine Fisheries.