Friday, January 22, 2021

A large number of gray whales are starving and dying in the eastern North Pacific


News Release 22-Jan-2021
It is now the third year that gray whales have been found in very poor condition or dead in large numbers along the west coast of Mexico, USA and Canada. A new international study now suggests that starvation is contributing to these mortalities.
Aarhus University


It's mid-January 2021, and the first gray whales from the eastern North Pacific population have started to arrive in the breeding lagoons in Baja California, Mexico. Since the start of their southbound migration from their high latitude feeding grounds, several sightings of emaciated gray whales have already been reported along their migration route.

This has raised concern among scientists that the unusual mortality event (UME, an unexpected phenomenon during which a significant number of a marine mammal population dies), that started in January 2019, and which so far has resulted in 378 confirmed gray whale deaths, and possibly many more unrecorded, is entering its third year.


A decline in prey availability on the main feeding grounds is hence the most probably explanation for the current UME. Since the late 1980s, there has been a decline in the abundance and biomass of amphipods, the main prey for gray whales, in the central Chirikov Basin, the main feeding area for gray whales in the Bering Sea. This in turn is believed to be caused by warming of Arctic waters as a result of natural and/or human-induced climate change. If that is the case, UMEs like this one might become more frequent, which could result in a decline in gray whale numbers in coming decades.


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