As seas warm, whales find home less hospitable

 In Science

Scientists worry that the humpbacks might have been forced elsewhere in a search for food as the seas grow rapidly warmer and their feeding grounds are disturbed.They are crossing into the paths of ships and fishing gear, and the death toll is climbing.

MOUNT DESERT ROCK, Maine —

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.

This chunk of rock, about 25 nautical miles from Bar Harbor, Maine, 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 here have underscored the growing perils along the East Coast to both humpback whales and North Atlantic right whales.

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This past summer, the numbers of humpback whales identified from the rock 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 a search for 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 Center for Ocean Life at the New England Aquarium. “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” in coastal New England in the 1700s, Kraus said.

The aquarium maintains a catalog 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.

From the office computer in Mount Desert Rock’s only house, researchers use 36,000 images depicting some 9,500 animals to track whales. It was on this island 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 Sept. 1 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 — at one of the fastest rates on earth — 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.

DenDanto and several investigators with Allied Whale, a group affiliated with the College of the Atlantic, plan to begin a research project next year, analyzing 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. Katona and his collaborators took pictures for the humpback whale catalog, 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, or No. 8. 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 Catalog, 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 — a distance of about 6,500 miles — proving that an animal the length of a school bus can travel a quarter of the way around the world.

The catalog 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.

Understanding the whales’ behavior remains key to helping them survive in warming waters shared with fishermen and ships, said Judy Allen, associate director of Allied Whale.

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