Government biologists in the US have launched a special investigation into the reasons behind the high number of gray whale deaths over the last few months, which they’ve called an ‘unusual mortality event’.
At least 70 gray whales have washed up on shores along the west coast of America, from California to Alaska, with many of them emaciated and underweight.
The die-off has been declared an ‘unusual mortality event’ by the National Oceanic and Atmospheric Administration (NOAA), which has allowed extra resources to be given so they can investigate the causes.
According to NOAA’s National Marine Fisheries Service, 37 dead gray whales appeared in waters off California, three in Oregon, 25 in Washington state, five in Alaska and five in British Columbia, as Huffington Post reports.
Officials said most of the whales have little body fat, leading them to suspect the die-off is the result of declining food sources in warming sea waters.
Grey whales spend the summer season in the northern Bering sea and Chukchi sea, off Alaska, where they consume a year’s worth of nourishment in order to pack on blubber before their migration south for the winter.
The Bering and Chukchi waters have recorded consistently higher temperatures than usual however, as a result of climate change, scientists suggest.
Sue Moore, a University of Washington oceanographer, said:
The Arctic is changing very, very quickly, and the whales are going to have to adjust to that. The sea ice has been changing very quickly over the last decade or so.
The lack of sea ice may be reducing the number of crustaceans, known as amphipods, which are the whales’ main source of food.
Another theory suggests the die-off is due to rising numbers of gray whales, saying the mammal’s population has reached the limit of the environment’s capacity to sustain it.
The current population of eastern North Pacific gray whales is around 27,000, the highest number since surveys began in 1967, according to biologist David Weller.
Keep in mind that carrying capacity is not a hard ceiling, but that it’s a shifting threshold. In some years or period of years the environment is capable of supporting more whales than in other years.
As a result, many whales are venturing into places like San Francisco Bay and Puget Sound, where they risk being hit by ships and boats.
The last major whale ‘die-off’ was in 1999 and 2000, and was believed to be caused by ocean warming due to an El Nino climate cycle.
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Charlie Cocksedge is a journalist at UNILAD. He graduated from the University of Manchester with an MA in Creative Writing, where he learnt how to write in the third person, before getting his NCTJ. His work has also appeared in such places as The Guardian, PN Review and the bin.