Three years of ‘health check-ups’ on Oregon’s summer resident gray whales shows a compelling relationship between whales’ overall body condition and changing ocean conditions that likely limited availability of prey for the mammals.

Researchers from the Geospatial Ecology of Marine Megafauna Laboratory at OSU’s Marine Mammal Institute used drones to monitor 171 whales off the Oregon Coast during the foraging season between June and October in 2016, 2017 and 2018.

They found that the whales’ health declined following a period of relatively poor upwelling — an ocean condition that brings colder, nutrient-rich water closer to the surface — compared to previous years.

«What we see is this compelling relationship between the oceanographic processes that control the quality and quantity of available prey and whale health,» said Leigh Torres, an assistant professor with the Marine Mammal Institute and the lab’s director. «This research gives us an inclination that changes in ocean conditions might be causing skinny whales.»

The findings may also provide insight into the unusual gray whale die-off event that occurred in 2019 along the Pacific Coast, Torres said. More than 200 gray whales were reported dead between Mexico and Alaska last year, including six in Oregon. Many of the deceased whales appeared to be in poor body condition, meaning they looked skinny.

The study was just published in the journal Ecosphere. The paper’s lead author is Leila Soledade Lemos, who recently completed her doctorate at Oregon State and worked with Torres in the GEMM Lab.

Story Source:
Materials provided by Oregon State University. Original written by Michelle Klampe. Note: Content may be edited for style and length.