Gray whales that spend their summers feeding in the shallow waters off the northwestern Pacific coast have experienced a significant decline in body length since 2000, according to a new study from Oregon State University. These reduced sizes could have critical implications for the health and reproductive success of the affected whales and signal potential issues within their food web, according to researchers.

“This could be an early warning sign that this population’s abundance is starting to decline or is not healthy,” said KC Bierlich, co-author of the study and assistant professor at OSU’s Marine Mammal Institute in Newport.

“Whales are considered sentinels of the ecosystem, so if the whale population is not doing well, it could indicate broader environmental problems.” The study, published in Global Change Biology, focused on the Pacific Coast Feeding Group (PCFG), a small subset of about 200 gray whales within the larger eastern North Pacific (ENP) population of approximately 14,500 whales. This subgroup stays closer to the shore along the Oregon coast, feeding in shallower, warmer waters compared to the Arctic seas where most gray whales spend the majority of the year.

The research highlights the length difference between a PCFG gray whale born in 2020 and one born before 2000. OSU researchers found that an adult PCFG gray whale born in 2020 would be 1.65 meters (about 5 feet and 5 inches) shorter than a gray whale born before 2000. For PCFG gray whales, which reach 38-41 feet in length at full maturity, this represents a reduction of over 13% in total length.

Recent studies from OSU have shown that whales in this subgroup are smaller and in worse physical condition compared to their ENP counterparts. The current study reveals that they have continued to shrink over the past few decades. Since 2016, the Geospatial Ecology of Marine Megafauna (GEMM) Lab at the Marine Mammal Institute has been studying this subgroup of gray whales, using drones to measure their sizes.

Lascia un commento

Il tuo indirizzo email non sarà pubblicato. I campi obbligatori sono contrassegnati *