Warming Atlantic pushes right whales to extinction – sciencedaily
Warming oceans have driven the critically endangered North Atlantic right whale population from its traditional and protected habitat, exposing the animals to more deadly ship strikes, disastrous entanglements in commercial fisheries and at significantly reduced calving rates.
Without improving its management, right whale populations will decline and potentially disappear over the next several decades, according to a report led by Cornell and the University of South Carolina in the journal. Oceanography.
“Most of the warming in the Gulf of Maine is not coming from the atmosphere or the ocean surface, as one might think,” said lead author Charles Greene, professor emeritus in the Department of Science. Earth and Atmosphere at Cornell. “It comes from the invasion of sloping waters several hundred feet below the ocean’s surface, forcing right whales to abandon their traditional habitat.”
Since 2010, the calving rate has declined and the right whale population has fallen by about 26%, according to the document. At the start of the decade, the North Atlantic right whale population numbered over 500 whales. Today, the North Atlantic Right Whale Consortium estimates the population at just 356 whales.
The species is considered critically endangered by the Red List of Threatened Species of the International Union for the Conservation of Nature.
The warm slope water entering the deep Gulf of Maine derives its heat from the Gulf Stream. As the tail of the Atlantic turning meridian circulation, the Gulf Stream has radically changed its course over the past decade.
“As a result of global warming, the meridional Atlantic overturning circulation is slowing, causing the Gulf Stream to shift northward, injecting warmer and saltier sloping waters into the Gulf of Maine,” Greene said.
Warming Gulf of Maine has reduced the abundance of copepods, the tiny crustaceans that serve as a favorite snack for right whales. This reduced calving rates for right whales and forced whales to abandon their feeding grounds in mid-summer in the Gulf of Maine. Instead, the whales headed north to the cooler waters of the Gulf of St. Lawrence.
Since 2015, scientists have observed an increase in the number of right whales feeding in the Gulf of St. Lawrence, where no protection was in place to prevent collisions with vessels and entanglement of fishing gear. This led to an unusual mortality event reported by NOAA in 2017, when 17 right whale deaths were confirmed, mostly in the Gulf of St. Lawrence. Ten right whales were found dead in 2019, while for 2020 and 2021, four deaths have occurred so far.
“Right whales continue to die every year,” said lead author Erin Meyer-Gutbrod, assistant professor at the University of South Carolina. “Protection policies must be strengthened immediately before this species declines beyond the point of no return.”
Oceanographers are hoping for new policies on cordless fishing gear, enforcement of vessel speed limits and money for ecosystem monitoring and forecasting.
Funding for this research was provided by the Lenfest Ocean Program.
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Material provided by Cornell University. Original written by Blaine Friedlander. Note: Content can be changed for style and length.