A new study, led by scientists at the Gulf of Maine Research Institute and colleagues at the University of Maine and NOAA, reveals how conservation practices by Maine lobstermen help make the state’s lobster fishery more resilient to the effects of climate change.
“We are proud of our conservation measures. Maine lobstermen believe in them and have known that they work long before science acknowledged it,” said Patrice McCarron, executive director of the Maine Lobstermen’s Association (MLA). “During the 80’s and 90’s, and into the 2000’s, the MLA lead the charge to get these measures accepted by scientists and managers. Guys knew they worked because it was common sense, but it took the scientists a bit longer to get there.”
Maine lobstermen toss back large lobsters and mark egg-bearing lobsters with a V-notch, which protects them from being harvested in the future
when not bearing eggs. This conservation culture is different from that of southern New England, where lobstermen had not taken the same steps to preserve large, reproductive lobsters.
The study, funded by the National Science Foundation and published in Proceedings of the National Academy of Sciences, shows how warming waters and contrasting conservation practices contributed to simultaneous record landings in the Gulf of Maine fishery and population collapse in southern New England. The research team used advanced computer models to simulate the ecosystem under varying conditions, allowing them to understand the relative impacts of warming waters, conservation efforts, and other variables. The results show that, while temperature change was the primary contributor to lobster population changes, conservation efforts made a key difference.
Over 30 years (1984-2014), ocean temperatures increased rapidly in both regions. Summer ocean temperatures began to increase, to the benefit of the Gulf of Maine lobster stocks and the detriment of the southern New England. The researchers estimate that, during this 30-year period, the Gulf of Maine population increased by 515%, while the southern New England population declined by 78%.
The study shows how conservation efforts prepared the Gulf of Maine lobster population for temperature changes. Researchers estimate that lobster population growth in the Gulf of Maine was more than double what it would have been without conservation measures. Model simulations showed that, without conservation measures to protect large lobsters and reproductive females, lobster abundance in the Gulf of Maine would have increased by 242% instead of 515%.
Temperature changes were disastrous for the southern New England lobsters, on the other hand, which were already at their southern biological range. Additionally, the region’s lack of protections on larger reproductive lobsters made the population less resilient amid warmer waters.
While scientists expect lobster populations to decline from recent highs, the 30-year outlook for the Gulf of Maine fishery looks positive if conservation practices continue. In their 30-year projection, the researchers anticipate average lobster populations in the Gulf of Maine to be similar to those in the early 2000s.
“Maine lobstermen fully recognize that our resource is at a record high and will not continue to go up. That’s how commercial fisheries are; they go up and down,” McCarron said. “We are fortunate to have real data on all life stages of the lobster through the DMR sampling programs, and those surveys continue to look steady. I’m not too worried about a 30-year prediction. Lobstermen will continue to adapt to changes in the fishery as we always have.”