SEATTLE (AP) — U.S. researchers say the number of gray whales off western North America has continued to decline over the past two years, a decline that resembles previous population fluctuations in recent years. decades.
According to a National Oceanic and Atmospheric Administration Fisheries assessment released Friday, the most recent count puts the population at 16,650 whales, down 38% from its peak in 2015-2016. The whales have also produced the fewest calves since scientists began counting births in 1994.
A rise in the number of whales stranded on west coast beaches prompted the fisheries agency to declare an “unusual mortality event” in 2019. Researchers are still investigating the mortality, but they say climate change and its effects on sea ice and prey availability and location are likely factors. Many, but not all, of the whales that got stranded appeared malnourished.
The population has recovered from the days of commercial whaling before a similar 40% population decline occurred in the late 1980s and early 1990s. Gray whales were removed listed as endangered in 1994.
The population rebounded before a spike in whale strandings on beaches led to the declaration of another “unusual mortality event” in 1999 and 2000, when whale numbers fell by a quarter.
Scientists say that although the current population trend so far matches historical patterns, it is nevertheless of concern.
“We need to monitor the population closely to help understand what may be driving the trend,” said David Weller, director of the marine mammal and turtle division at the Southwest Fisheries Science Center in San Diego.
Researchers count the whales as they return from their summer feeding grounds in the Arctic to the lagoons of the Baja Peninsula where they nurse their young in the winter. Typically, counts are made 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 the central California coast from end of December to mid-February 2023. .
Calves are counted as the whales head north towards the Arctic. There were 217 calves in the tally that ended in May, up from 383 the previous year.