The grey whale population along the US west coast is recovering after an "unusual mortality event" ended. The NOAA estimates the current population at 17,400 to 21,300, up from 13,200 to 15,960 the previous year.

Around 690 grey whales were found dead from 2018 to 2020, peaking between December 2018 and December 2020. Changes in the ecosystem and prey quality in the Arctic are thought to have led to the whales' malnutrition and increased mortality.

Grey whales migrate annually from the Arctic to Mexico, and were delisted from endangered species in 1994 due to prior recovery from whaling impacts.