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The
38% drop from the population's 2016 high of 27,000 whales to
16,650 this year resembles previous fluctuations but warrants
further attention, the National Oceanic and Atmospheric Research
Administration (NOAA) report said.
Researchers at NOAA's Southwest Fisheries Science Center in San
Diego said the latest decline, though not fully explained,
likely entails several factors including environmental changes
that have shifted the whales' food sources of tiny crustaceans
and other invertebrates they prey on in the Arctic.
"Given the continuing decline in numbers since 2016, we need to
be closely monitoring the population to understand what may be
driving this trend," David Weller, director of the center's
marine mammal and turtle division, said in comments announcing
the findings.
A spike in gray whale strandings detected along the West Coast
of North America from Mexico through Alaska two years ago
prompted NOAA Fisheries to declare an "unusual mortality event"
for the population in 2019, triggering closer scrutiny of the
phenomenon.
Many of the roughly 600 whales found washed up dead on beaches
from 2019 to this year appeared malnourished, though some had
died from other causes, such as boat collisions or attacks from
killer whales, NOAA said.
The overall population slump among West Coast gray whales
coincides with diminished reproduction, researchers found.
The most recent count of baby whales that ended in May estimated
calf production this year at about 217 newborns, down from 383
calves tallied last year and the lowest number since such counts
began in 1994, NOAA fisheries said.
Gray whales, one of the largest animals on Earth weighing up to
41 tons and reaching lengths of 49 feet (15 meters), are known
for their visible annual 10,000-mile (16,000-km) migration
between feeding grounds in the Arctic and breeding grounds in
Baja Mexico.
Gray whales of the eastern Pacific Ocean have seen sharp
declines before, as in the late 1980s and early 1990s when their
numbers similarly dropped roughly 40% before rebounding to a new
high point, according to NOAA.
Commercial whaling once drove gray whales to the brink of
extinction, but they have recovered enough to have been removed
from the Endangered Species List in 1994.
(Reporting by Steve Gorman in Los Angeles)
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