Right whale population decline linked to ocean warming, research says

The endangered North Atlantic right whale faces increased odds because its main food supply has shifted due to ocean warming, according to new research.

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Scientists have been searching for an explanation for a precipitous decline in the North Atlantic right whale population, which has dropped from 482 in 2010 to about 411 today.

A paper by 17 authors from the US, Canada and Norway, published this month in the journal Oceanography, links an influx of warm water in 2010 to a reduction in the whales’ key food supply, Calanus finmarchicus, a small crustacean, in the Gulf of Maine, the area off the US coast in which the whales spend their summers.

As the food supply moved in response to ocean warming so did the whales, apparently putting them closer to shipping lanes and fishing locations that had been designed to avoid the whales’ usual feeding grounds. Whales also faced traveling farther for food and feeding earlier in the year, leaving them more hungry than usual before winter.

“The right whale population is not healthy and more time spent foraging may lead to additional mortality, amplifying the challenges this species faces,” the paper said.

Also concerning was that the ocean warming detected in the whales’ feeding zone is expected in other parts of the ocean.

According to the report, “rapid warming at the level observed in the Gulf of Maine is likely to be a more prominent feature of the future ocean”.

North Atlantic right whales give birth off Georgia and Florida in winter before feeding in the Gulf, which touches Massachusetts, New Hampshire, Maine and Canada, in the spring and summer.

Docile and slow-moving, the animals tend to stay close to the coast. That made them relatively easy targets for whalers who drastically reduced their population in the late 18th and early 19th centuries. It became illegal to hunt the right whales in 1935.

There was hope the population would rebound but in the past decade it has become clear the whales are among the most endangered species in the world. In 2017, at least 17 right whales died. In 2018, no calves were born. That prompted new measures to protect the whales from industrial fishing lines and large vessels.

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The paper challenged the assumption that species can adapt quickly to changing ocean conditions. Instead, the authors wrote: “Low calf production is an indication that [the whales] are not yet able to forage well in these new habitats.”

There is some hope, however, that the whales will rebound – scientists have spotted seven calves this year.

Researchers said that by studying North Atlantic right whales’ movements, they hope to be able to better understand if conservation efforts are adequate as the impact of climate change becomes more acute. The Gulf of Maine has been one of the fastest-warming ocean ecosystems on the planet since 2004.

The Massachusetts representative Seth Moulton, who is seeking the Democratic presidential nomination, sponsored a bill to save the whales with a decade-long, $50m program. The House has not yet voted on the bill. A similar measure has been filed in the Senate.