Climate Change, Pesticides Shift Lobster Populations North

1 06 2016

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Warming waters from climate change off the Atlantic coast are driving lobsters further north than ever before, disrupting fisheries and – for some – perhaps changing a way of life forever.

While the southern New England lobster fishery has all but collapsed, fishers in Maine, Prince Edward Island and even further north are benefiting from the crustaceans’ movement.

“I’ve seen enough of the charts to say the water’s warming, and if that’s climate change, it’s happening. It is happening,” says Beth Casoni, executive director of the Lobstermen’s Association of Massachusetts.

Casoni estimates some 30 fishers still trap lobster in southern New England, down from hundreds previously. The impacted areas include Southern Massachusetts, Rhode Island, Connecticut and New York.

At the same time the lobster fishing in Maine and north has exploded. Maine is seeing historically high landings now, roughly five times higher than it was back in the 1980s and ‘90s.

It’s a similar story in P.E.I., where lobster landings have gone from a low of 17.6 million pounds in 1997 to a high of 29.7 million pounds in 2014.

Off of Nova Scotia, fishers are calling the 2015-2016 season one of the best in the last decade and estimate the lobster catch at 75 million pounds.

There have even been reports of fishers trying to secure lobster fishing licences in the northern Gulf of St. Lawrence off of Quebec and Labrador – a cold-water region which previously hasn’t supported a lobster fishery.

Fisheries scientist Richard Wahle attributes the collapse of the southern New England lobster fishery to climate change and points to previous mass die-offs in Long Island Sound as a result of extreme warm temperatures.

During 1999 to 2000, the Long Island Sound die-off resulted in a 75 per cent drop in lobster landings.

“It’s important to take it all in,” Wahle says, “because when you look to the southern end of the species’ range, that’s where we see some signs of trouble. Those areas which have historically been at the southern end of the species range have really been seeing a collapse of the fishery.

“There are pretty strong signs they are related to climate warming: ocean warming, the onset of diseases like shell disease.”

Richard Wahle. Photo from Richard Wahle

Wahle leads a lab named after him at the University of Maine and is one of the leading experts on lobster population trends and settlement.

A 2015 paper Wahle co-authored in ICES Journal of Marine Science noted southern New England’s summer water temperatures surpassed a long-recognized 20 degree Celsius physiological threshold, causing the lobsters to shift north.

That creates a “scenario whereby coastal southern New England will no longer be a hospitable nursery to the American lobster in the coming decades,” the researchers wrote.

“You’ve got to think of it not so much as a case of lobsters are packing their tents and moving north, as much as they’re more successfully repopulating every year in the northern locations relative to the southern location,” Wahle says.

Every year lobsters produce eggs which hatch as larvae. The larvae spread out over large distances, ranging over hundreds of kilometres. As they settle into their nursery habitat along the coast, their survival is higher in the northern waters now.

The larvae are surviving in areas such as the Bay of Fundy, which historically has been colder than what is comfortable for the crustaceans. According to Wahle, in the south the nursery habitat is moving away from the warmer shore water and into somewhat deeper water.

But offshore the habitat isn’t as good, without the rocks for shelter they would find closer to shore.

A Wahle Lab film about lobster larvae. Video from YouTube

In the Gulf of Maine, since 1980 the temperatures have been rising on average at the rate of one degree Celsius every 40 years. But in the last decade that’s changed. Consistent with global warming, the temperatures are now increasing at a rate of one degree about every four years.

As the temperatures rise, so do the incidences of shell disease. Wahle describes the latter as a “nasty looking disease” with dramatic effects on the lobster’s exoskeleton. It’s a bacterial infection that dissolves the shell, pitting it and rendering the lobster unpalatable for sale.

In its most severe forms, the disease can cause blindness, prevent the lobster from molting – when it sheds its exoskeleton – and interfere with its hormonal system. In the latter case, the disease causes the molt to occur right when it shouldn’t. For example, an egg-bearing female might suddenly cast off its skeleton, taking the eggs with it.

The disease is present in some 30 per cent of the harvestable size lobster caught in southern New England, Wahle says.

Malin Pinsky, an assistant professor in the Department of Ecology, Evolution and Natural Resources at Rutgers School of Environmental and Biological Sciences in New Jersey, calls the northward movement of lobsters over the last five decades dramatic. In that period of time, the crustaceans has shifted more than 273 kilometres northward.

Pinksy studies how climate change impacts coastal marine species and fisheries. “We’re seeing these kinds of effects across a wide range of marine animals, everything from fish to crabs to lobsters.”

The environmental and economic movements of the northern migration doesn’t only have evnrionmental and economic impacts. It could also affect international relations, Pinsky said.

He pointed to the so-called mackerel wars of 2010 to 2014. Those took place between a number of European Union countries and Iceland after warming waters sent the mackerel closer to Iceland in search of more hospitable temperatures.

A spat over the fish and fishing boundary disputes led to trade sanctions, tariffs and other economic measures.

Climate change or pesticides?

Robert Bayer isn’t as certain that climate change is effecting the lobsters. Bayer is a professor of animal and invertebrate science at the University of Maine and executive director of the Lobster Institute, a U.S.- Canada group that carries out research and education.

Bayer contends that the collapse of the industry south of Cape Cod may be partially caused from temperature changes. But he says if you look at a map, that’s where the megalopolis of all the major cites are grouped together and that pesticide run-off from lawns, golf courses and roads are a likely culprit.

“I think that’s probably just as important as climate change, water temperatures.”

But Wahle doesn’t buy that theory. “I think the jury’s still out on that,” he says.

While Wahle says the link in temperature is circumstantial, he calls it “strongly circumstantial” noting strong correlations between prevalence of the shellfish disease and the temperature.

Wahle says pesticides may be a factor and that many are hormone disrupters, but he asks why in New England did shell disease suddenly appear in 1997, going from almost nothing to impacting 30 per cent of the catch.

“I’m not aware of any evidence that pesticides started to become more widely used at that time, but we do know that it [shell disease] came… after eight years of well above average temperatures in Southern New England.”

Oil and gas development another risk for lobster

While the lobster’s migration north might be a good thing for Canadian fishers, if climate change doesn’t get the crustacean, oil and gas development just might.

Corridor Resources wants to develop an offshore oil and gas field known as Old Harry, a field approximately 30 kilometres long and 12 kilometres wide in the Gulf of St. Lawrence, 80 kilometres off the coast of Newfoundland and Labrador and partially in Quebec’s waters.

But fisher associations oppose the development. Leonard Leblanc of the Gulf of Nova Scotia Fishermen’s Coalition based in Cheticamp, Cape Breton, said Old Harry is a current concern of theirs.

Leblanc says the Gulf is ice-covered most years and in the event of a well blow-out with oil spewing under water, it would be impossible to clean up because the oil would be trapped under the ice. The gulf’s swirling currents would also disperse the oil widely, leaving no area safe from pollution.

Ecojustice and the Sierra Club Canada Foundation have also both protested the development. Sierra Club described the gulf as “too precious to be placed at risk by oil and gas development.”

For its part, Corridor has characterized the risk of a blow-out as low and says the “majority” of the invertebrate fisheries are located 25 kilometres away from the edges of the project area and outside the “Predicted Maximum Extent of Oil Plume Trajectory in Relation to Exploratory Licence 1105.”

Leblanc says the lobster stock is healthy and reproducing at a rate higher than he has ever seen it reproduce.

But it will only remain that way if proper management of the lobster continues. “Lobster can provide for us as long as we take care of it,” Leblanc says. “If we don’t, we’re going to have a major problem.

“We’ve had the collapse of the ground fishery and that really hurt the East coast. I suspect the collapse of the lobster fishery would hurt even more, so we have no choice but to take care of it.”

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