Lobsters Plump Up on ‘Fast Food’

Maine lobsters are fattening up on herring that lobstermen put out as bait in their traps, according to a study that shows that bait is the main food in a lobster’s diet.

The study supports the long-held belief that lobster traps essentially act like fast-food restaurants for lobsters off the Maine coast.

It also suggests that the huge amount of herring bait -- Maine lobstermen use about 220 million pounds annually -- is contributing to the healthy lobster stocks and the extensive catches of recent years.

Jonathan Grabowski, a scientist with the nonprofit Gulf of Maine Research Institute, said it reveals that lobsters that ate herring grew 16% more on average last summer and fall than lobsters without herring in their diets.

The findings were presented in August at the Ecological Society of America’s annual conference in Georgia and at this year’s Maine Fishermen’s Forum in Rockland.

“A lot of the research was motivated by the industry suspicion that herring might be important as a subsidy to lobster populations,” said Grabowski, who led the study. “This study certainly supports that notion.”

Fishermen have long said that putting bait, herring being the most popular, in traps amounts to feeding lobsters by supplying them with free meals.

Little lobsters can freely crawl in and out of traps until they grow large enough to be trapped.

Besides bait, lobsters generally eat crabs, mussels, clams, snails, urchins, worms and, on occasion, each other.

For the study, Grabowski and a research technician last summer used dive equipment to collect lobsters from the ocean bottom a few miles off the mid-coast fishing village of Port Clyde, and more lobsters off of Monhegan, an island about a dozen miles off the coast.

The project also included scientists from the University of Maine and the Department of Marine Resources, and lobster fishermen from Port Clyde and Monhegan.

To determine the diet makeup, scientists analyzed the lobsters’ stomach contents and conducted a chemical analysis of the lobster meat.

They found that herring made up 33% to 55% of the diet of lobsters off Port Clyde.

The lobsters off Monhegan, however, had little or no herring in them.

That’s because lobstering is banned there from June into November, meaning that there are no herring-filled traps in the water in those months.

The study also raises questions about the long-term effects that could result from lobstermen, in essence, feeding lobsters much like farmers feed their animals.

What happens, for instance, when you take 220 million pounds of herring out of the ecosystem to feed another creature in the ocean?

With so much herring in the water, are crabs, mussels and other lobster prey under less pressure from lobsters and more likely to survive?

Bob Bayer, executive director of the Lobster Institute research and education organization, said the findings also underscore the importance of herring as a bait source for fishermen.

He said herring is a pop- ular food among consumers in Europe and could grow in popularity among American eaters.

If that happens, lobstermen could face severe herring shortages.

“There’s barely enough herring to go around,” Bayer said.