Scientists predict Maine’s lobster boom will end within 5 years

October 24, 2019

Maine’s lobster boom – in which landings have quintupled since 1990 – may be coming to an abrupt end, according to a new scientific study.

The study predicts landings will fall 20 percent to 40 percent in the next four to five years in much of eastern Maine, and by over 90 percent in the eastern part of Penobscot Bay, the heart of the recent lobster explosion.

“The sky is not falling, but we are returning to normal, to the levels of the late 1990s and early 2000s,” says Noah Oppenheim, the Maine-born executive director of San Francisco’s Institute for Fisheries Resources and the leader of the study published by the scientific journal Ecological Applications. “Fish buyers, fishermen, fish processors and policy makers can start thinking about where this is going to be impacting people the most.”

Scientists, managers and industry leaders caution that because the Gulf of Maine is changing so fast – it is the second-fastest warming part of the world’s oceans – lobsters may be changing their behaviors in ways the study is not capturing, which might delay or mitigate the predicted downturn.

“This is a cautionary time for anybody in the wild-caught market because of the changes in environmental conditions,” says Patrice McCarron, executive director of the Maine Lobstermen’s Association, which represents some 1,200 harvesters. “But I think the industry is at a place where they’re still seeing tons of tiny lobsters out there.”

For decades in the early and mid-20thcentury, Maine lobstermen caught about 20 million pounds of lobster each year. But starting in 1990 – and for reasons that are still debated – the catch began to increase steeply, surpassing 30 million pounds in 1991, 50 million in 1999 and 80 million 10 years later. The catch has exceeded 100 million pounds every year since 2011, hitting a jaw-dropping 132.6 million in 2016 before ticking downward to 119.6 million last year.

The forecasts in the new study – which Oppenheim conducted with colleagues at the University of Maine and the Gulf of Maine Research Institute – are based on an improved version of the current lobster forecasting model, which has successfully extrapolated the future condition of the lobster fishery from surveys of tiny baby lobsters in their traditional, shallow-water nursery grounds. The study is being published in Ecological Applications on Wednesday.

The new model incorporates bottom water temperatures and associated shell disease effects, and when the researchers tested it using historical baby lobster survey data, it produced considerably more accurate forecasts of lobstermen’s catches six and seven years later, when the babies had grown to legal catch size. This gave the researchers confidence in its predictive ability.

When they fed the past few years’ baby lobster data – the so-called settlement surveys, because the babies have newly settled on the bottom after beginning their lives as floating plankton – the model delivered stark results for almost all of Maine’s seven lobster fishing zones, with the sharpest declines in eastern Maine and adjacent parts of the New Brunswick coast, and a more modest fall in southern and midcoast Maine.

“I always emphasize that we don’t have a crystal ball here, but by and large the model appears to be performing pretty well and it does point to a pretty widespread downturn,” says co-author Richard Wahle, a marine zoologist and head of the Wahle Lab at the University of Maine’s Darling Marine Center. Still, he says, there is some reason for hope that the model’s forecasts are overly pessimistic.

That’s because the model is based on surveys of newly settled baby lobsters at longstanding study sites in the only types of habitats they were found in any numbers: underwater cobble and boulder fields close to shore, where the babies could find shelter and water temperatures that aren’t too cold (at least 53.6 Fahrenheit) or too hot (above 68, which kills them.) The new forecasts assume, perhaps incorrectly, that most of the future lobster catch is spending its early childhood in such places.

But another new paper by Wahle and three University of Maine colleagues suggests that may not be the case, as climate change is altering the lobster’s world and, thus, the places where many of them may spend their infancy and youth. This second paper, in the journal Global Change Biology, suggests that as the Gulf of Maine has warmed, the area of thermally appropriate baby lobster habitat has expanded. This is especially in true in eastern Maine, where the powerful tides flowing in and out of the Bay of Fundy mix the exceptionally warm surface water down to the seafloor where the lobsters are. (In western Maine, the warm water generally stays on top, leaving much of the bottom too cold for the infant crustaceans.)

“In the 1990s, when we had a cooler Gulf of Maine, we found newly settled lobsters in this little bathtub ring in Maine’s embayments and settlement was confined to the upper 60 feet. But we don’t believe that’s the case any longer,” says lobster scientist Robert Steneck, who helped create the original lobster settlement model and is a co-author of this second study. “Without a doubt, they are settling in eastern Maine, especially in deeper water.”

This, the UMaine team says, may explain why Eastern Maine has seen the sharpest increase in landings in recent years but also might offer hope that there are a lot more healthy infant lobsters settling out there in the sea than the new forecasting model assumes.

“Those forecasts may be overly pessimistic if this deepwater settlement is offsetting those severe declines we predict based on shallow-water settlement alone,” says Wahle, who worked on both papers. “So that’s the uncertainty that we are left with at this moment, so to some extent we have to take a wait-and-see approach to this.”

Carl Wilson, a lobster biologist who now directs the Department of Marine Resources’ Bureau of Marine Science, agrees but says most everyone expects the boom will come to a close.

“I believe there’s broad acknowledgment that the last 10 years have been just extraordinary for lobster and that people don’t have the same expectations for the same increases in the future,” he says. “It’s OK to come out of the stratosphere, but it’s been so long, we’ve kind of forgotten what normal used to be like.”