Biologists and lobstermen are growing increasingly worried that the state’s most valuable fishery, which in recent years has boasted record volume and value and accounts for more than 80 percent of Maine’s fishing profit, is about to go bust, a doomsday economic scenario some call the curse of the “gilded trap.”

At the center of their concern: The number of baby lobsters found in the Gulf of Maine continues to fall.

Scientist are diving deep into the details of the decline, trying to understand what is happening to the baby lobsters, or if changing ocean conditions in the Gulf of Maine mean they aren’t looking for them in the right places anymore. That may explain why the lower baby lobster count that started one decade ago has yet to lead to lower catches.

“We call it the great disconnect,” said Joshua Carloni, New Hampshire’s state lobster biologist. “And as you can imagine, it has us concerned.”

Because it takes a lobster about seven years to grow big enough to harvest, and the bulk of the annual Maine haul is lobster that is just large enough to catch, state lobstermen should have seen their landings fall over the last three years. But instead, fishermen have enjoyed record high value and volume, landing $533.1 million in lobster in 2016. Biologists say lobster abundance has doubled since 2000.

This kind of mystery excites Rick Wahle, a University of Maine research professor at the Darling Marine Center who has been studying – and counting – lobsters for years. He’s the founder of the American Lobster Settlement Index, the annual count of young lobsters that repopulate New England’s coastal lobster nurseries. These young lobsters have just spent about four weeks floating in the open sea as plankton before “settling” on the ocean floor.

It is this “settler” count that has dropped over the last decade.

“We don’t have a crystal ball,” said Wahle. “We are always fine-tuning our forecasting models. It’s important to remember that when our models predict one thing, and we get another, that right there tells us we’re missing an important variable we need to include to make the prediction more accurate. It could have implications for how we manage the fishery.”

So biologists like Wahle, including a number of current and former graduate students from the University of Maine System, are investigating the “great disconnect” between the baby lobster decline and the continued growth in catches. They want to know whether Maine should prepare for – or take management steps to prevent – a catastrophic decline in future lobster landings.

Researcher after researcher at last week’s International Conference and Workshop on Lobster Biology & Management in Portland talked about work underway to explore the disconnect, ranging from an examination of how rising ocean temperatures might have forced the larvae to “settle” in new spots where surveyors aren’t counting, to whether new predators are eating them or gobbling up all their food supply.

‘NOWHERE TO BE FOUND’

First, scientists need to understand the reason for the sharply declining “settler” count from Massachusetts north to New Brunswick. Maine’s lobster biologist, Kathleen Reardon, told a meeting of lobstermen on Swans Island last summer that she didn’t want to scare them, but that the baby lobsters “are just nowhere to be found – gone.”

Initially, biologists thought warming waters might be hurting lobsters’ ability to mate or produce viable eggs, but data collected for decades by the Seabrook Station Nuclear Power Plant in New Hampshire show the number of first-stage lobster larvae, the youngest larvae, found in its weekly ocean tows near Hampton Beach has grown right along with the number of sexually mature lobsters found in local waters.

That means lobsters are producing more eggs than ever, which rules out overfishing as the culprit, said Carloni, the New Hampshire lobster biologist. What’s no longer found in high numbers in Seabrook’s weekly tows, however, are fourth-stage larvae – small lobsters ending their four-week float through the open ocean and starting to visit the ocean floor in search of food and shelter. If there is a doomsday coming, this is the scientific ground zero.

So what’s happening to the end-stage larvae? Data show it’s not rising ocean temperatures – at least not directly, Carloni said. In fact, the temperature of the ocean at Seabrook, and up and down the coast of Maine, is actually ideal for all stages of lobster larvae, he said.

In a report delivered at the conference, Carloni and Wahle raised the possibility that these late-stage lobster larvae may be starving. The Seabrook tows found a decline in copepods – tiny planktonic crustaceans that are most likely a staple of the lobster larval diet – that closely mirrors the decline in fourth-stage lobster larvae. The scientists hope to test this theory next summer by conducting gut checks of the surviving lobster larvae.

There could be other factors at play that may explain the decline in both the late-stage larvae and the copepods. Changing ocean currents could be pushing the lobster larvae and the copepods out of the sampling area and forcing the lobsters to settle someplace new. A new predator, such as jellyfish, could be feasting on one or both of the species.

LOOKING AHEAD

Wahle, Carloni and others want to understand the reason for the decline in counted settlers so they will know what’s going on, but also to tweak the model that other researchers, including some of Wahle’s graduate students, use to forecast the number of lobsters hitting legal harvest size each year and, most importantly, annual lobster landings. Can the lobster boom continue?

Most forecast models say no, despite the abundance of juvenile and adult lobsters in other surveys and industry conservation efforts, the record-high landings can’t continue, but they differ on when the fall will occur and how bad it will be. One of Wahle’s former graduate students, Noah Oppenheim, has developed a model using sea temperature and the settlement index that predicts the entire Maine coast will see significant landing declines by 2020.

One of his new students, Andrew Goode, said the Gulf of Maine’s rising temperature could expand the amount of seabed where baby lobsters settle well beyond the traditional test sites. Including his expanding thermal habitat in the forecast model makes for a more optimistic future, including several more years of strong lobster landings and a softer decline in catch once it does happen.

Goode’s work has inspired Wahle and Reardon, the Maine state lobster biologist, to initiate a research project with Maine’s fishing industry and funded by Maine Sea Grant to use collectors deployed from lobster boats to explore the possibility of lobster settlement in the deep waters of the Gulf of Maine.

This kind of variation in forecasts confuses and frustrates fishermen and regulators, but researchers say it is part of the scientific process. Scientists acknowledge unquantified variables, like how rising temperature may affect lobster predators, can skew forecasts, but that shouldn’t stop them from trying to look for warning signs that might prevent a collapse of the fishery and the coastal communities that rely on it.

“We don’t want to be Cassandras, we don’t want to be technocrats, and we certainly don’t want to cry wolf, but we do want to be able to use the tools that we develop to make good decisions,” Oppenheim said, referring to the figure in Greek mythology fated never to be believed. “We might be able to use this approach to enhance our ability to maximize catch, keep fishing boats on the water and enjoy lobster in perpetuity.”

Penelope Overton can be contacted at 791-6463 or at:

poverton@pressherald.com

Twitter: PLOvertonPPH

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