2023-10-18 13:47:57
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Scientists link the mass death of gray whales to changing conditions in the Arctic. Photo/Live Science
WASHINGTON – Three mass death events gray whale (Eschrichtius Robustus) off the west coast of North America has occurred since the 1980s. Scientists linked the incident to changing conditions in the Arctic.
Three events mass death of whales grayling off the coast of North America since the 1980s, resulting in population declines of 15% to 25% annually. In total, more than 2,000 gray whales are known to have died.
The first mass die-off occurred between 1987 and 1989 and was the largest, killing at least 700 whales. The second event occurred between 1999 and 2000, killing 651 whales.
The most recent deaths occurred in 2019 and resulted in more than 70 gray whales stranding themselves in just six months. Currently ongoing, as of September 26 2023, a total of 688 whales have died.
However, the cause of this incident is not clear. According to a new study published Oct. 12 in the journal Science, this unusual mortality event is linked to changing conditions and fluctuations in sea ice levels in the Arctic.
“This is an extreme population change that we did not expect would occur in a large, long-lived species like the gray whale,” said Joshua Stewart, assistant professor at Oregon State University’s Marine Mammal Institute, quoted by SINDOnews from the Live Science page, Wednesday (18/10 /2023).
Sea ice cover and the amount of food available to gray whales can determine how the population fares. Higher than normal ice cover in some years may prevent passage to the Bering and Chukchi seas, where whales spend the summer months feeding on fatty crustaceans before migrating south again.
“When the availability of prey in the Arctic is low and whales cannot reach feeding areas due to sea ice, gray whale populations experience rapid and major shocks,” Stewart said.
Unlike the previous two events, the historic loss of Arctic sea ice could be the cause of the latest gray whale deaths. This happens because sea ice harbors beds of algae on its underside, which rot and shower the seabed with food for seafloor dwellers, including the crustaceans that whales love.
“With less ice comes less algae, which is bad for the gray whale’s prey. “All of these factors combine to reduce the quality and availability of the food that (gray whales) rely on,” Stewart said. Melting sea ice also paves the way for powerful currents that sweep away sediment and leave bottom-dwelling crustaceans and other creatures homeless.
(wib)
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