Gray whales. NOAA
A group of gray whales that spends its summer on the Oregon coast is shrinking, with young whales on track to be around 5 feet shorter than their elders, a new study finds.
In total, more than 14,000 gray whales roam the northeastern Pacific, which extends from Mexico to Alaska, and most spend their summers in the Arctic. The new study focused on just 200 whales that linger in the warm, shallow waters along the coast of Oregon and tend to be in worse shape than other gray whales.
Researchers from Oregon State University used drones to monitor these whales and gauge changes in their size over time. They found that, while a whale born in the year 2000 could be expected to grow to around 40 feet in length, a whale born in 2020 would end up closer to 35 feet in length. Researchers said the shift in size is dramatic, comparable to the average American woman shrinking from 5 feet, 4 inches to 4 feet, 8 inches in the space of just 20 years.
The study, published in Global Change Biology, echoes other research finding that many fish, birds, and amphibians are shrinking, and that climate change may be playing a role. One explanation is that smaller creatures cope better with high heat. Another is that in a hotter, more turbulent world, some animals are not getting enough to eat, and so are not growing to full size.
For gray whales, the drop in size coincided with a shift in upwelling currents, which draw nutrients from the deep and deposit them in shallow waters along the coast. With climate change, researchers said, winds are shifting and the ocean is growing warmer, though it is not yet clear what effect this may be having on upwelling.
Scientists warned that a drop in size poses a threat to the long-term survival of the Oregon gray whales. Shorter whales tend to have smaller reserves of blubber, meaning they have less energy stored away for lean times. Experts worry that these shorter whales will have a harder time recovering from boat collisions and other injuries, and may struggle to reproduce.
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