Despite their names, they don’t actually “trap” at all. Using undersea cameras to spy on a trap, scientists discovered that only 6% of lobsters that wandered into a trap stuck around long enough to get hauled to the surface. Why do so many lobsters mosey through and then leave? For the all-you-can-nibble herring, naturally.

In this Wednesday, July 8, 2015 photo, herring are unloaded from a fishing boat in Rockland, Maine. New England fishermen are catching staggering amounts of herring, signaling the rebounding of a fishery that collapsed in the early 2000s. But some conservationists and rival fishermen say the fishery, which is important for both food and bait for tuna and lobsters, is wiping out other fisheries with its massive pelagic trawlers. (AP Photo/Robert F. Bukaty
With cod gone, herring catches have boomed.
Image: AP Photo/Robert F. Bukaty

There are close to four million traps in Maine waters, says Steneck—each one packed with about a pound of bait per day. ”Most of the lobsters that go into traps are undersized and can’t be harvested,” he says. “They get a free meal.”

All those free meals boost the population—and the industry. GMRI researchers calculated that during trapping season, herring accounts for between a third and half of lobsters’ diets. Those in areas with traps grow 16% faster than lobsters in areas without, according to their research. This extra heft also adds around $40 million a year to the value of Maine’s lobster haul.

The success of this domestication process perpetuates itself. As other fisheries founder, both Maine’s fishermen and the state’s economy have grown increasingly reliant on its swollen lobster haul. The lobster fishery’s total economic impact on the state economy was $1.7 billion, as of 2012—more than 3% of Maine’s GDP that year.

However, twilight may already falling on Maine’s two-decade crustacean heyday. Though the contents of this season’s lobster traps signal nothing but bounty, scientists are uncovering grim omens from under the rocks below.

Bad news from the baby lobster census

The first comes from Rick Wahle’s annual survey of baby lobster settlement. Using scuba divers and, in deeper water, retrievable boxes that simulate cobble, he and his team have counted baby lobsters at more than 100 sites in Maine, Massachusetts, Rhode Island, and Canada, a few for more than 25 years. As you’d expect, their findings suggest that wherever baby lobsters settle in big numbers, adults soon abound.

Wahle’s team surveys the Gulf of Maine’s cobble for baby lobsters.
Wahle’s team surveys the Gulf of Maine’s cobble for baby lobsters.
Image: Rick Wahle

What about the obverse, though? We’re about to find out.

In the last few years, Wahle and his team have tracked what he calls a “widespread and deep downturn” in the number of settled baby lobsters. Though there have been decreases at certain sites before, the signals they’re picking up now are different.

“We’ve seen other downturns—they blink on and blink off. But we’ve never seen all of them blink on like that.”

The slump in babies started around 2011, which means “the next two years are going to be very telling because of that downturn in settlement,” says Wahle.

The case of the missing lobsters

DATE IMPORTED:August 25, 2013Lobsterman Steve Train tosses a lobster back into the sea while hauling traps in his boat "Wild Irish Rose" in the waters off Cape Elizabeth, Maine August 21, 2013. Lobster populations in Maine are booming like never before. The number of lobster processing plants in the state has more than tripled, from 5 in 2010 to 16 last year. Picture taken August 21, 2013. To match Feature USA-LOBSTER/REUTERS/Brian Snyder
Image: Reuters/Brian Snyder

What’s strange is that, by all reckoning, Maine’s lobster population should be at an all-time high—which means baby lobsters ought to be too. There are also more breeders than ever before. The state’s lobsters are better fed, better protected, and—in the upper Gulf of Maine, at least—they and their babies enjoy more favorable sea temperatures than at any time in history.

“That we see such a dramatic decline in settlement here at a time when brood stock, the spawners, are at peak levels of abundance—there must be an environmental factor here,” says Wahle.

There are a couple of things that this could mean. One is what Steneck—he works closely with Wahle, a former student of his—calls the “deep water hypothesis.”

In the past, most larvae likely settled in the upper 60 feet or so of the coastal shelf, where waters were sufficiently warm. However, cobblestone and rocky ledges extend a ways offshore in places, perhaps 100 feet down. So as the water has gotten balmier, they’ve been able to make their homes farther offshore—in waters that used to be too cold for them—well beyond where Wahle and his team are looking for them. The kids, in other words, are alright.

In another scenario, they’re not, though. Steneck says that deeper water—where lobsters spend winter—seems to be warming faster even than shallow areas. If this means a females’ eggs mature and hatch while she is still far offshore, her babies could be carried out to sea by currents into waters too cold and deep for babies to survive.

“The first scenario, if true, would be very positive, the second one very negative—it would mean we’re going to see a significant downturn [in landings],” says Steneck. “I just don’t think we have a clue which one of those is correct.”

On the bright side, the first scenario jibes with reports from fishermen who’ve been hauling up baby lobsters and juvenile lobsters in unusually deep waters, suggesting that babies are successfully settling there. But new research on female lobster fecundity could tip the scale in favor of the much grimmer outlook.

Trouble with Grand Manan’s big mamas

The findings raise the possibility of another culprit entirely: Female lobsters are suddenly producing fewer eggs. This seems unlikely given the prime baby-making conditions created by the warming seas. However, recent research (paywall) led by Heather Koopman, a biologist at the University of North Carolina, suggests this might be happening—and ocean warming is probably why.

This August 2009 picture shows a female lobster laden with eggs before being released back into the ocean off Long Island near Harpswell, Maine. The Maine Department of Marine Resources announced Monday, March 1, 2010 that Maine lobstermen had a record harvest in 2009, but the value of the catch continued to plunge amid the sour global economy. Lobstermen caught 75.6 million pounds last year, up 8 percent from 2008, but the value of the catch fell $23 million, to $221.7 million. (AP Photo/Pat Wellenbach
An egg-bearing female lobster caught in Harpswell, Maine.
Image: AP Photo/Pat Wellenbach

To analyze lobster fecundity, Koopman and her team tagged along with lobstermen working the waters near Grand Manan Island, in Nova Scotia’s Bay of Fundy. Home to some of the biggest female lobsters ever recorded, the island is also a spawning hotspot for the whole region, an important source of current-carried larval emigres far down Maine’s coast. Before tossing back each “egger” that the lobstermen hauled up, Koopman and her team counted her eggs (or took digital pictures so they could tally them later). Over five years, they sampled some 1,370 lobsters, building one of the biggest collections of data on lobster reproduction ever amassed.

The results were disconcerting. From 2008 to 2013, the average number of eggs they counted on a lobster’s underside declined by 30%—a drop of around 8-10% a year.

Canadian bakin’?

DATE IMPORTED:August 25, 2013A lobster sits in a holding bin before having its claws banded by sternman Rob Tetrault II (rear) onboard the lobster boat "Wild Irish Rose" in the waters off Cape Elizabeth, Maine August 21, 2013. Lobster populations in Maine are booming like never before. The number of lobster processing plants in the state has more than tripled, from 5 in 2010 to 16 last year. Picture taken August 21, 2013. To match Feature USA-LOBSTER/ REUTERS/Brian Snyder
A lobster caught off Cape Elizabeth, Maine.
Image: Reuters/Brian Snyder

What might explain this alarming drop in fecundity? Stress from handling, pollution, disease, and lack of oxygen could in theory be factors.

However, the most likely cause, hypothesized Koopman and her team, is the rapid rise in water temperatures. While some warming is obviously favorable to lobster populations, too much is dangerous. A female lobster’s ovaries mature when temperatures drop somewhere below the 41°F to 46.4°F range. During the five years of the study, water temperatures never fell below 41°F, and only a few times below 46.4°F. If Koopman and her teams’ hypothesis is right, it also doesn’t bode well for egg production further south, in waters already much warmer in winter than the Bay of Fundy.

Another possible factor behind the Grand Manan Island fecundity decline could be that there simply aren’t enough big male lobsters left to go around. Female lobsters generally prefer mating with bigger males. That’s not as easy as it used to be though, explains Tracy Pugh, a Massachusetts state fisheries biologist who specializes in lobster reproduction. The more rigorous protection of eggers (Maine’s conservation policies are the norm in Canada too) makes it highly likely that many more females than males will avoid harvest long enough to reach the 5-inch legal limit.

So what happens when females outnumber males, or exceed them in size? In labs, at least, mating doesn’t always work out so well. Guy lobsters that try to get it on with bigger females sometimes simply fail to get the job done. Others release too little sperm to fertilize all of the large female’s eggs. And when females outnumber their counterparts, males sometimes can’t keep up with the demand. However, Pugh emphasizes that lab results don’t always reflect what happens in the wild.

Still, whatever is behind it, the fecundity decline of Grand Manan’s big mamas could indeed explain why fewer babies are making it to Maine cobbles than before.

The coming collapse?

FILE - In this July 29, 2014 file photo, Brandon Demmons sends a lobster trap overboard at dawn off of Monhegan Island, more than 12 miles off the coast of Maine. A two-year shutdown of the Maine shrimp season is keeping many lobstermen at sea deeper into the winter than typical, a trend some say could result in lower prices at lobster pounds. Many Maine lobstermen use the shrimp season as a source of winter income while lobsters are in lower demand and harder to catch. (AP Photo/Robert F. Bukaty
Image: AP Photo/Robert F. Bukaty

These disquieting data might just be statistical noise—or they may foretell a reversal in the Gulf of Maine’s two-decade lobster boom. If any fishermen can weather such a downturn, it’s Maine’s lobstermen. Tempered by tradition, discipline, and the collective will of generations, their practices exemplify the long game of biological and economic sustainability that far too many other fisheries decline to play.

As the Maine’s lobster industry’s improbable rise reveals, no single species exists in a vacuum. Unfortunately, conservation efforts don’t either. Two decades of lobster abundance isn’t thanks to human mastery of ”sustainability.” The ecosystem extremes that seem likely to have produced it—how we’ve pulled apart the food web, heated up the sea, re-rigged the lobster population structure—are volatile. Inevitably, nature warps again.

If recent research is truly flashing a warning sign, that warping may already be underway. For most, that means that the local lobster roll food truck might switch back to selling kimchi tacos. But for a state whose identity is married to the iconic big-clawed crustacean, the stakes are much higher.

“We’re not talking about lobstermen having a bad decade,” says UMaine’s Steneck. “We’re talking about the entire maritime and coastal heritage of the coast of Maine.”

Lobster roll image by Yuri Long on Flickr, licensed under CC-BY-2.0 (image has been cropped). Juvenile lobster image by Rick Wahle via NOAA Photo Gallery on Flickr, licensed under CC-BY-2.0 (image has been cropped). Image of Maine cod fisherman by rich701 on Flickr, licensed under CC-BY-2.0 (image has been cropped). 

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