West Coast’s gray whale population plummets by thousands since 2016, NOAA says. Why?

A quarter of the West Coat’s gray whale population has died since 2016, according to a new report from the National Oceanic and Atmospheric Administration.

The population dropped by more than 6,000 whales in five years, according to NOAA. An estimated 20,580 whales are currently part of the population, down from at least 26,960 in 2016.

“The decline coincides with an ongoing Unusual Mortality Event that NOAA Fisheries declared in 2019 for gray whales when strandings increased on the West Coast,” NOAA reported.

During the “unusual mortality event,” hundreds of gray whales died. Since Jan. 1, 2019, researchers found at least 386 gray whales stranded along the coasts of North America, McClatchy News reported.

The overall population decrease is similar to one that happened two decades ago between 1999 and 2000, according to NOAA. After a similar unusual mortality event, the gray whale population decreased by 23%.

The change “suggests that large-scale fluctuations of this nature are not rare,” scientists said in a NOAA Fisheries report. “The observed declines in abundance appear to represent short-term events that have not resulted in any detectable longer-term impacts on the population.”

Scientists have seen an increase of elevated gray whale strandings, which contributes to the population decline.

Between 4% and 13% of whale deaths are due to strandings, according to NOAA.

“During the UME, the West Coast Marine Mammal Stranding Network counted 122 gray whale strandings in 2019 in the United States, including Alaska,” NOAA reported. “They counted 79 in 2020. That is higher than the annual average stranding of roughly 29 gray whales over the previous 18 years.”

This story was originally published January 20, 2021 at 9:00 AM with the headline "West Coast’s gray whale population plummets by thousands since 2016, NOAA says. Why?."