November 6, 2018 — For years, Maine shellfish harvesters have been complaining that there are fewer softshell clams while arguing that the diggers who go out on the mud flats aren’t the cause of the problem.
A recent study by researchers from NOAA’s Northeast Fisheries Science Center and the Maryland Department of Natural Resources backs them up on both counts.
According to Clyde L. MacKenzie Jr. of NOAA and Mitchell Tarnowski from the Maryland Department of Natural Resources, between 1980 and 2010, documented landings of the four most commercially important inshore bivalve mollusks along the Northeast coast — eastern oysters, northern quahogs, softshell clams and northern bay scallops — dropped by 85 percent.
The principal cause, they say, was warming ocean temperatures associated with a shift in the North Atlantic Oscillation which resulted in damaged shellfish habitat and increased predation from Maine to North Carolina.
“My first response is that the article confirms what I have been seeing with soft-shell clams over at least the last decade or so,” Brian Beal, a professor of marine ecology at the University of Maine Machias and director of research at the Downeast Institute on Great Wass Island, said last week.
The North Atlantic Oscillation is a fluctuation of atmospheric pressure over the North Atlantic that affects both the weather and the climate along the East Coast, especially in winter and early spring.
According to NOAA, shifts in the oscillation can affect the timing of a species’ reproduction and growth, the availability of microscopic organisms for food and predator-prey relationships.
Over a period of several years, MacKenzie and Tarnowski interviewed shellfish wardens and harvesters along the New England coast, as well as examining landings records and other research in an effort to determine the “true causes” of the precipitous drop in shellfish landings.