Change in food source has lured right whales down a dangerous shipping lane

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Until recently, researchers tracking the welfare of the world’s most endangered large whale could count on North Atlantic right whales appearing in several key areas at certain times of the year in search of food. , love, or a safe place to give birth.

In winter and early spring, a large portion of right whales could be found in Cape Cod Bay feeding on copepods, their favorite food. They then moved to Bay of Fundy for summer feeding, where researchers at the New England Aquarium had been studying them since the 1980s.

But in 2010, and in the years that followed, they were gone. Although they still showed up in Cape Cod Bay, over the past decade the Bay of Fundy has been largely a right whale ghost town. The same was true for the Great South Channel east of Cape Cod and the northern edge of Georges Bank.

It took a combination of detective work and luck to finally find them – and where they ended up dramatically altering the landscape for whale survival and fisheries management.

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“Where did they go when they left New England waters in the winter?” “Said Tim Cole, fisheries biologist at National Oceanic and Atmospheric Administration Northeast Fisheries Science Center, echoing a question posed by researchers across New England in the years after 2010.

It should be relatively easy to find a 55 foot long, 70 ton black and white whale, especially when there are only over 300. But when they can swim virtually anywhere in the 20 or so million square miles of the North Atlantic, the task of locating the North Atlantic right whale is incredibly difficult.

“It’s a big ocean and they’re very mobile. It’s a real tip for tracking people,” Cole said.

Warming water displaces key food source

As to why they left their former summer trampling grounds, it may have a lot to do with climate change.

Andrew Pershing, the former chief scientist of the Gulf of Maine Research Institute, along with other scientists, believe that in 2010 the Gulf of Maine, which stretches from Georges Bank to the Canadian border, underwent what is called regime change – a sudden change in environmental conditions that is not easily reversible.

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The reason the Gulf of Maine has warmed faster than almost any other ocean body of water on earth may be due to a weakened global current known as the Atlantic Meridional Reversal Circulation. Also known as the Great Ocean Conveyor, AMOC is a collection of currents, including the Gulf Stream, that move north along the surface, propelled by water heated by the equatorial sun. As it cools in northern latitudes, this water densifies and sinks, returning south to the equator as a collection of cold water currents slowly creeping along the bottom.

Normally, a cold current from Labrador and Newfoundland cools the Gulf of Maine. It creates a subarctic ecosystem that is home to cold water species like cod, haddock, northern shrimp, and lobster. And, more importantly for the right whale, this subarctic environment is home to its favorite food, the fat-rich copepod Calanus finmarchicus

But the melting Greenland glaciers have created a layer of fresh water on the ocean’s surface that prevents the salt water from sinking, and scientists believe that has slowed the conveyor down.

Pershing and other researchers believe weakened cold water currents moving north to south allowed warm southern water to enter the Gulf of Maine through the northeast channel. They believe the temperatures have become too warm for Calanus finmarchicus and the right whales to set out to find copepod flowers in unknown places.

“In 2012, 2013, everyone was asking, ‘Where are the right whales going? “,” Said Peter Corkeron, Principal Scientist and Chairman of the Kraus Marine Mammal Conservation Program at the Anderson Cabot Center for Ocean Life at the New England Aquarium.

They had two fairly obvious but important clues to consider in their search for very social and highly mobile animals.

“They want to be around women,” Cole said. “It’s all about food and sex.”

U.S. researchers, in consultation with Canadian scientists, believed some may have moved to colder Canadian waters when finmarchicus blooms occurred. In 2015, Yvan Simard, specialist in krill for the Canadian Department of Fisheries and Oceans, working on the ecology of this whale’s forage species, began picking up many right whale sounds at the underwater listening posts he had set up to monitor shipping lanes in the Gulf of St. Lawrence.

Cole, who works with other scientists conducting aerial surveys to find and document right whales, was able to negotiate with the Canadian government to bring the NOAA plane to the Gulf of St. Lawrence to search for them in 2015. But 2017 was the first year they had the funding and the time to do a thorough search – and they located a lot of right whales, Cole said.

Danger in the shipping lanes of the Gulf of St. Lawrence

An article published this fall in the Endangered Species Research online journal of Canada’s aerial surveys, by lead author Leah Crowe of Integrated Statistics in Woods Hole – along with Cole, Corkeron and other NOAA researchers, Anderson Cabot and Canadians – found that 40% of the right whale population was found in the Gulf of Saint-Laurent from May to December. and that most of them – 140 – have returned year after year.

Unfortunately, Canadians did not have whale protections similar to those in the United States, such as weak links on lobster and crab buoy lines that would loosen under pressure, or shipping lanes that have. been relocated to carry heavy maritime traffic beyond feeding areas or migration routes.

The result was a record year of human-caused mortalities, with 17 right whales confirmed to be dead (12 in Canada and five in the United States). As of 2017, there have been 34 confirmed dead whales (21 in Canada and 13 in the United States) and another 16 with injuries from collisions or vessel entanglements that are deemed likely to be fatal. Scientists have estimated that in order for right whales to rebuild themselves and avoid extinction, less than one animal per year may perish from human causes.

In 2017, the aerial survey was repeatedly interrupted as they spotted dead, injured or entangled right whales and had to suspend their efforts to help rescue or autopsy teams locate the animals.

“We got there and the first thing DFO asked us was if we could go out and locate a carcass, and it just went on and on. It was horrible,” Cole said.

The Canadians were able to act quickly and decisively on the information provided to them by Cole’s team and through their own investigative work. In fact, Corkeron, who previously worked for NOAA on whale research, said they had done a better job.

When security measures take too long to implement

“NOAA is a long way from what Canadians are doing,” he said. Canadian DFO has more power to act quickly, quickly closing areas to fishing and transportation once a single right whale is seen.

“It’s a lot of work and it takes a lot of work on the ground, but it seems to be working to keep the fishery going and not killing a lot of whales,” Corkeron said. By comparison, he cited the tedious NOAA process in which emergency fishing closures can take weeks or nearly a month to be enacted – and perhaps too late. Boating speed limits in areas where right whales have been sighted are voluntary and regularly violated.

“They (the Canadians) have much tougher measures and they can be implemented quickly,” Corkeron said. Massachusetts lobster vessels might argue otherwise, as nearly all state waters remain closed to gear using buoys during the winter and early spring when right whales are here.

Yet it took years amid the constant threat of litigation for NOAA to hatch a plan to reduce the number of buoy lines in New England, make the equipment safer for whales, and mark it. so researchers can tell where the whales are tangling.

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Corkeron called Cole an unsung hero for his hard work in finding whales in the Gulf of St. Lawrence. He said the study that led to their article showed that a plane could find whales.

But many questions remain unanswered. Are right whales getting what they need to survive in the Gulf of St. Lawrence? While Calanus finmarchicus copepods flourish there, as do two other species of copepods which may be less nutritious.

“We don’t know if the resource in the Gulf of St. Lawrence is really good and attracts whales there, or if it’s just better than elsewhere,” Cole said.

But while they know where 40% of right whales are in summer, where are the remaining 60% and do they go to areas where they might encounter buoy lines and ships?

“More than half are not there for 12 months, and there is that 40% elsewhere for seven months of the year,” Corkeron said.

“The rest are scattered over a pretty large area,” said Cole – hard to find, hard to protect.

Still, Cole is reassured that with less than 100 females of reproductive age remaining, around half of successful breeding mothers use the Gulf and appear to be getting the food they need to produce calves.

“That makes it a pretty big place,” Cole said.

Follow Doug Fraser on Twitter: @dougfrasercct

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