Warming sea endangering lobster stock

Robert F. Bukaty/AP file photo/A study published on Monday said conservation practices have allowed the northern New England lobster industry, based in Gloucester, Rockport and in Maine, to thrive in the face of rising ocean temperatures while the southern New England lobster catch has plummeted. Ocean temperatures have risen in both areas, to levels that scientists said is favorable for lobsters off northern New England and Canada but inhospitable for them in southern New England. 

Is the lobster boom on the decline in the Gulf of Maine because of warming waters? A newly released study by a Maine-based marine research group suggests that is the case.

The study, released Monday by the Gulf of Maine Research Institute, touched on many of the same climate issues that have left researchers and lobster stakeholders anxious about the future.

“In the Gulf of Maine, the lobster fishery is vulnerable to future temperature increases,” GMRI said in the statement released with the study. “The researchers’ population projections suggest that lobster productivity will decrease as temperatures continue to warm, but continued conservation efforts can mitigate the impacts of future warming.”

The study, compiled with the University of Maine and NOAA Fisheries, said the anticipated decline highlights the need for vigilant conservation within the Gulf of Maine lobster fishery, especially since scientists say the gulf’s waters are warming faster than 99 percent of the rest of the world’s oceans.

Researchers said they expect the lobster population to decline from recent highs — GMRI pegs the peak year at 2010, when it estimated the Gulf of Maine lobster stock contained 518 million lobsters — to levels more in keeping with traditional lobstering years.

It estimates the population could shrink to about 261 million lobsters in 2050.

“The 30-year outlook for the Gulf of Maine fishery looks positive if conservation practices continue,” GMRI said. “In their 30-year projection, the researchers anticipate average populations similar to those in the early 2000s.” 

Beth Casoni, executive director of the Massachusetts Lobstermen’s Association, said lobster stock assessments in the Gulf of Maine have shown the annual settlement of young lobsters — when they transition from floating in open waters as plankton to settling on the bottom to begin the seven- to eight-year stretch it requires to mature — has declined from previous assessments.

“And that gives us reason to anticipate that catches in the next five to seven years will be down,” she said.

Casoni said the study’s conclusion underscored the need for lobstermen to regularly perform V-notching — where a “v” is cut into the tail of egg-bearing females — to help identify and protect the spawning females.

“We strongly encourage all lobstermen to V-notch,” Casoni said Tuesday. “We understand that there are still some who are not doing this and it’s very important that they engage in this practice. This is their essential stock and they need to protect it.”

In Gloucester, which remains the top lobster port in Massachusetts, this was not the best summer for lobstering.

While final lobster landings for the season are incomplete, local lobstermen uniformly agreed that the 2017 season was an obvious departure from the previous years that provided record volume and value in the numbers of lobsters landed locally and throughout the Gulf of Maine.

The study concluded that lobster conservation may be the key to mitigating the detrimental impact of the warming waters. Researchers in the study estimate that without decades of V-notching and size-specific fishing, the growth in the gulf’s lobster population would be half of what it is today.

“For generations, lobstermen in Maine have returned large lobsters to the sea and have designed a special way of marking egg-bearing lobsters to give them further protection,” GMRI said in its summary of the study. “This conservation culture distinguishes the Gulf of Maine from southern New England where fishermen have not historically taken the same steps to preserve large, reproductive lobsters.”

Contact Sean Horgan at 978-675-2714, or shorgan@gloucestertimes.com. Follow him on Twitter at @SeanGDT.