SHELLFISHERIES IN HOT WATER
Study: Rising ocean temps ruin habitats of clams, scallops
Valuable species of shellfish have become harder to find on the East Coast because of degraded habitat caused by a warming environment, according to a pair of scientists that sought to find out whether environmental factors or overfishing was the source of the decline.
The scientists reached the conclusion in studying the decline in the harvest of four commercially important species of shellfish in coastal areas from Maine to North Carolina — eastern oysters, northern quahogs, softshell clams and northern bay scallops. They reported that their findings came down squarely on the side of a warming ocean environment and a changing climate, and not excessive harvest by fishermen.
One of the ways warming has negatively impacted shellfish is by making them more susceptible to predators, said the lead author of the study, Clyde MacKenzie, a shellfish researcher for the National Oceanic and Atmospheric Administration who is based in Sandy Hook, N.J.
“Their predation rate is faster in the warmer waters. They begin to prey earlier, and they prey longer into the fall,” MacKenzie said. “These stocks have gone down.”
MacKenzie’s findings, the product of a collaboration with Mitchell Tarnowski, a shellfish biologist with the Maryland Department of Natural Resources, appeared recently in the journal Marine Fisheries Review.
The study mirrors what Maine clam harvesters are seeing on the state’s tidal flats, said Chad Coffin, a clammer and the president of the Maine Clammers Association. Maine’s harvest of softshell clams — the clams used to make fried clams and clam chowder — dwindled to its lowest point since 1930 last year.
It will take adopting new strategies, such as shellfish farming, for the fisheries to survive, Coffin said.
“Clammers aren’t the reason there’s no clams,” he said. “We need to adapt, we need to focus our efforts on adapting to the environment we have.”