Killer whale populations are dying. New study helps researchers understand why
Humans could be a major cause of death for killer whales, new research says.
Historically, experts have known killer whales have been threatened by hunting and culling, food limitations, chemical contamination and vessel traffic, according to the National Oceanic and Atmospheric Administration (NOAA).
The new research, however, shows that the harm humans cause may not be limited to those indirect issues — we are also directly killing them.
“Nobody likes to think we’re directly harming animals,” SeaDoc Society Director Joe Gaydos, a wildlife veterinarian with the Karen C. Drayer Wildlife Health Center, said in the news release. “But it’s important to realize that we’re not just indirectly hurting them from things like lack of salmon, vessel disturbance or legacy toxins. It’s also vessel strikes and fish hooks. That humans are directly killing killer whales across all age classes is significant; it says we can do a better job.”
Researchers looked at pathology reports of more than 50 killer whales that died in the northeast Pacific and Hawaii and found that some of the biggest threats to orcas stem from human interactions, a UC Davis news release said.
The researchers looked at whales that came from healthy and endangered populations found off the coasts of British Columbia, Washington and Oregon. While there were no singular causes of death among those whales, human-caused deaths were found in every age group, according to UC Davis.
“Causes of calf mortalities included infectious disease, nutritional, and congenital malformations,” the study said. “Mortalities in sub-adults were due to trauma, malnutrition, and infectious disease and in adults due to bacterial infections, emaciation and blunt force trauma.”
While the report doesn’t dive into the overall health of orca populations, it can help better understand what is causing their deaths and find ways to mitigate those issues, lead author Stephen Raverty said in the news release.
“This work contributes to a better understanding of the impacts that ongoing human activities and environmental events have on killer whales,” Raverty said.
