As seas warm, whales face new dangers

As seas warm, whales face new dangers

From the top of the six-story lighthouse, water stretches beyond the horizon in every direction. A foghorn bleats twice at 22-second intervals, interrupting the endless chatter of herring gulls.

At least twice a day, beginning shortly after dawn, researchers climb steps and ladders and crawl through a modest glass doorway to scan the surrounding sea, looking for the distinctive spout of a whale. Mount Desert Rock, which is about 25 nautical miles from Bar Harbor, Maine, USA, is part of a global effort to track and learn more about one of the sea’s most majestic and endangered creatures. So far this year, the small number of sightings at Mount Desert Rock have underscored the growing perils along the East Coast to both humpback whales and North Atlantic right whales.

This past summer, the numbers of humpback whales identified here were abysmal — the team saw only eight instead of the usual dozens. Fifty-three humpbacks have died in the past 19 months, many after colliding with boats or fishing gear. Scientists worry that the humpbacks might have been forced elsewhere in search of food as the seas grow rapidly warmer and their feeding grounds are disturbed. “Food is becoming more patchy and less reliable, so animals are moving around more,” said Scott Kraus, vice president and chief scientist at the Anderson Cabot Centre for Ocean Life at the New England Aquarium, USA. “The more you move around, the higher the chance of entanglements.”

The North Atlantic right whales, which prefer colder waters, also are on a changed course — with even more dire consequences. Fifteen of the animals have died since mid-April in a population that has now slipped to fewer than 450. “We haven’t seen this level of mortality in right whales since we stopped whaling them,” Scott said.

Catalogue of images
The New England Aquarium maintains a catalogue of images of North Atlantic right whales, in part to track their population levels. The pictures, spanning decades, are crucial to understanding these elusive leviathans. Researchers use 36,000 images depicting some 9,500 animals to track whales. It was on Mount Desert Rock in the 1970s that scientists first confirmed that each whale’s fluke pattern is unique. A humpback’s tail is an unchanging signature and as distinctive as a face — except if it has been struck by a ship, bitten by a shark or slashed by a fisherman’s gear.

The high number of humpback deaths from January 2016 to September 2017 led the National Oceanic and Atmospheric Administration to declare an “unusual mortality event.”

No one knows exactly what’s going on, but the agency’s investigations attributed half of the deaths to ship strikes. The Gulf of Maine is warming rapidly and the temperature change might be causing shifts along the food chain, said Dan DenDanto, station manager at Mount Desert Rock’s Edward McC. Blair Marine Research Station. As the whales follow food sources into new areas, they wander into the paths of ships and into fishing gear.

Dan and several investigators with Allied Whale, a group affiliated with the College of the Atlantic, USA, plan to begin a research project next year, analysing bits of skin from humpbacks, collected using biopsy darts, to determine what the animals are eating and how that affects their health. Steven Katona, a co-founder of Allied Whale, was one of the first researchers to begin identifying whales here in the 1970s.

Steven and his collaborators took pictures for the humpback whale catalogue, which later confirmed their hunches that fluke patterns were consistent across a whale’s lifetime. In 1975, they named one of the first North Atlantic humpbacks na00008. The whale has been spotted three times since: in Canada’s Gulf of St Lawrence in the 1980s, off the coast of the Dominican Republic in 1993, and earlier this year off the coast of New Jersey.

“We have only a handful of sightings of this whale, yet these link together the efforts of collaborators spanning much of the North Atlantic,” Peter T Stevick, a senior scientist with the North Atlantic Humpback Whale Catalogue, said in an email. The sightings occurred in four distinct humpback habitats, providing insights into where these giants feed, breed and migrate. Another sighting matched a whale in Brazil to one observed in Madagascar proving that an animal the length of a school bus can travel a quarter of the way around the world. The catalogue has also allowed researchers to see that the whales breed at the edge of the Caribbean Sea, then fan out to traditional feeding areas, from the East Coast to Newfoundland, Labrador, Greenland and Iceland.

Chronicling the population
Understanding the whales’ behaviour remains key to helping them survive in warming waters shared with fishermen and ships, said Judy Allen, associate director of Allied Whale. “These are animals that are difficult to study,” Judy said. “They spend most of their lives underwater. We see a brief glimpse when they lift their tails out of the water and somebody happens to be there with a camera.”

The North Atlantic Right Whale Catalogue, managed by the New England Aquarium, includes images of 722 whales, chronicling the population since the early 1970s. The work has been particularly crucial this year, when there have been so many unexplained deaths. Twelve carcasses have turned up so far this year in Canada and three more in US waters; only five calves were born, as far as researchers can tell. The latest estimates, released by the New England Aquarium, put the population of North Atlantic right whales at 458 — but that was before this year’s deaths, Scott said.

Flying 750 to 1,000 feet over the animals also allows researchers to check on their health, making sure they are not dragging fishing ropes or bearing new scars, said Charles Mayo, director of the Right Whale Ecology Programme at the Centre for Coastal Studies in Provincetown, Massachusetts. Right whales are baleen whales, so they filter feed, supporting their 70-tonne weight solely with microscopic animals called zooplankton. That search can push whales into shipping lanes, where the animals are sometimes struck, or into the gear of fishing boats.

Despite protection efforts, about 80% of right whales bear scars from past entanglements or ship strikes. “They are remarkably built for a life in an ocean, which unfortunately is changing,” Charles said. He worries that “they’re not finding what they need where they ought to.”

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