New peril for gray whale survival? Predatory orcas spotted in Baja calving lagoon
The gray whale population off the coast of southern Baja has plummeted after being decimated by ship strikes and whaling, a new study says.
The researchers examined the stomach contents of 13 gray whales stranded in the Baja California Peninsula from 2005 to 2011, finding that many of them contained bits of marine plastic.
“With the gray whales and the whaling, the ocean has become more hazardous,” lead author Kevin Trenberth, a scientist with the National Center for Atmospheric Research in Boulder, Colorado, said in a statement. “We are looking at more animals, and these animals are becoming more abundant and are becoming larger and more abundant.”
An orcas kill. (Photo: Jeff Ross for The Huffington Post)
The researchers said that the whales found last year in Oregon and Washington state were a sign of a rapidly growing population, but that Baja’s population could soon shrink because of the orcas’ predation.
“The orcas and their predators are increasing in number and are eating more of the gray whales,” Trenberth said. “It’s a natural consequence of these increased numbers. But it’s also a growing threat, because the whales are going to be much smaller.”
A different problem is that marine plastic debris has become a problem for the gray whales by acting as a magnet to microorganisms in their stomachs, which the authors said could have negative impacts on the health of the animals.
“These microorganisms are known as opportunistic bacteria or opportunistic pathogens and it’s the bacteria that can make them sick,” said Mark Eliscu, an author of the paper and researcher at the Oregon State University Marine Mammal Laboratory.
The ocean has become more hazardous. (Photo: Jeff Ross for The Huffington Post)
The study was published March 12 in the journal Science Advances.
When orcas are not attacking gray whales, they are using the animals’ milk to feed their