Lobster and Warming Trends

What’s the New Normal?

by Laurie Schreiber

ROCKPORT – The theme of a seminar on lobster science, at the Maine Fishermen’s Forum in March, was that “times are changing.”

That was the word from Department of Marine Resources (DMR) lobster biologist Carl Wilson.

Wilson said that, if anything, there is less certainty about the status and future of the Gulf of Maine lobster population now than there was when he first took the job, 12 years ago. Part of that uncertainty is likely due to rising water temperatures, Wilson and other speakers said.

Over the past quarter-century, Wilson said, there has been a clear trend of increasing ocean temperature. Eight of the 10 warmest years since 1905 have occurred since 2001, he said.

There has been a corresponding boom in the lobster population. Over a 100-year time series, average landings were 27 million pounds.

“We crossed over that average in 1989 and we’ve been on a one-way trip [up] since that point,” Wilson said. Initially, he said, he thought the 10- to 15-year increase would settle to a “new normal.” Instead, he said, “I’m not sure where we are right now and I’m not sure where we’re going.”

Water temperatures did not cool down this winter, Wilson said.

“I was really hoping that this winter would be a little bit of a reset,” he said. “It doesn’t look like it’s going to be. We’re already getting reports of soft lobsters.”

DMR scientist Robert Russell said his studies confirm the trend overall is warmer water. Conditions could be creating more nursery habitat, he said; at the same time, they make it harder to say where larval settlement will be.

DMR inshore trawl survey scientist Keri Stepanek said that, overall, the survey is seeing a steep increase in lobster numbers. Sixty-five to 75 percent of the survey’s catch is sub-legal, just a month or two away from becoming legal. Ten percent is legal size, and everything else is oversize. The tow takes increasing numbers of lobster each year, everywhere from New Hampshire to the Canadian border, she said.

Increasing lobster abundance seems to correspond with changes in temperature, Stepanek agreed.

The tow also sees fewer fish, Stepanek said. The tow is getting a lot of whiting, especially juveniles, and alewives seem to be doing all right. But as far as groundfish, she said, “it’s safe to say we’re not seeing as much as we have in the past.”

DMR scientist Kathleen Reardon, said the agency’s sea sampling program and ventless trap survey have also documented an increase in sub-legal egg-bearing lobsters. Reardon said the studies have also shown an increase in shell disease, although still at a very low rate compared with southern New England, where shell disease sometimes approaches 30 percent.

“Our levels are still very low, but it’s something we look at. We’ll keep you posted,” Reardon said.

Islesford fisherman Jack Merrill said that one of the things he’s noticed is that some of the lobsters he’s caught have had chewed antennae. “To me, that’s a sign of stress and possible overcrowding,” Merrill said. “At what point do you start to worry about overpopulation?”

“I don’t think we’re at an overcapacity situation,” said Wilson. “But we are certainly in a situation very different than we were 25 years ago. To me, that starts to speak to the uncertainty and the fragility of the system. It’s certainly been demonstrated around the world that populations that have exponential increases are sometimes followed by rapid and dramatic decline. Certainly that’s what happened in southern New England. There are a variety of factors that happened in southern New England, some of which may apply here and some don’t.”

The University of Maine School of Marine Sciences’ Rick Wahle reported on a conference in Portland, last November, called “American Lobster in A Changing Ecosystem.” There, he said, lobster scientists discussed environmental stressors; population connectivity and the source/sink dynamics in larval supply from one region to another; food webs, the role of predator/prey dynamics, and the importance of cod and other groundfish; and fishing and the human dimension.

“We haven’t had a chance to do this since 1993, to get together as a lobster science community to do a progress report,” Wahle said.

“[DMR Commissioner] Pat Keliher pointed out that lobster really are the economic engine of Maine and the past decade or so has presented us with an amazing amount of uncertainty about the future of this fishery,” Wahle said. “There have been surprises that have come along with respect to the sheer abundance of lobsters. But also, who would have predicted the financial crisis in 2008 would have caused the price to just plummet and that would create such havoc with the industry now? What is clear is that it’s important to be prepared for surprises. And the work that Jim Wilson and the economists are doing along the coast in understanding that uncertainty, and preparing through our management process and through industry efforts, is really important to do.”

Monitoring programs are key to scientifically understanding the changes, said Wahle. “It develops our ability to develop these predictive tools and early warning systems,” he said. “At the end of the day, I think the key message that came out of the conference is that we can’t think of lobsters outside of the context of the ecosystem in which it exists, and that it’s important for the industry to be adaptive to change.”

“These monitoring programs have to keep going because it is our little glimpse into, potentially, what’s coming,” Wilson said. “But we also have to look into our programs and say, Are we missing things?”

Said Wilson, “If the next hundred years goes another two or three degrees increase like we’ve seen in the past hundred years, then things are going to be very different.”