SEATTLE – U.S. scientists say the number of gray whales in western North America has continued to decline over the past two years, a decline that echoes previous population fluctuations over the past several decades.
According to a National Oceanic and Atmospheric Administration estimate released Friday, the latest count puts the population at 16,650 whales — down 38% from 2015-16. The whales also produced the fewest calves since scientists began counting births in 1994.
An increase in the number of whales washed up on West Coast beaches prompted the Fisheries Agency to declare an “unusual mortality” in 2019. Researchers are still investigating the extinction, but say climate change and its effects on sea ice and prey. availability and location are likely factors. Many, but not all, of the beached whales appeared malnourished.
The population recovered from the days of commercial whaling before a similar population decline of 40% occurred in the late 1980s and early 1990s. Gray whales were removed from the endangered species list in 1994.
The population rebounded before a spike in beached whales prompted another “unusual mortality” declaration in 1999 and 2000, when whale numbers dropped by a quarter.
Scientists say that while the current population swing so far fits historical patterns, it is still worrisome.
“We need to monitor the population closely to understand what may be driving this trend,” said David Weller, director of the marine mammal and turtle division at the Southwest Fisheries Science Center in San Diego.
Scientists count whales as they return from summer feeding grounds in the Arctic to lagoons on the Baja Peninsula where they nurse their calves in winter. The census is usually conducted over a two-year period, but to better monitor the population, NOAA Fisheries is adding a third year to the current survey, counting whales as they pass through the central California coast from late December to mid-February 2023. .
Calves count as whales heading north to the Arctic. There were 217 calves in the count that ended in May, down from 383 a year earlier.