What's killing killer whales?

https://www.eurekalert.org/pub_releases/2020-12/uobc-wkk120120.php

News Release 2-Dec-2020
University of British Columbia

Pathology reports on more than 50 killer whales stranded over nearly a decade in the northeast Pacific and Hawaii show that orcas face a variety of mortal threats--many stemming from human interactions.


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Of 52 whales stranded between 2004 and 2013, causes of death were determined for 42 percent. For example, one calf died from sepsis following a halibut hook injury. Another starved from a congenital facial deformity. Two whales died from the blunt force trauma of vessel strikes. Additional causes of death include infectious disease and nutritional deficiencies.

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Despite there being no singular common cause of death, the study found a common theme: Human-caused deaths occurred in every age class -- from juveniles to subadults and adults.

"In British Columbia, we lost nine southern resident killer whales: 2 adults, 2 subadults and 1 calf died from trauma; one was a confirmed propeller strike, with one adult and two subadults from suspected ship strikes," said lead author Stephen Raverty, a veterinarian pathologist with the BC Ministry of Agriculture and adjunct professor at UBC's Institute for the Oceans and Fisheries. "One of these iconic species passed away from an infection secondary to satellite tagging. Another death was due to natural causes and the other two undetermined. Half of the southern killer whale deaths identified in this study were caused by human interactions."

"Nobody likes to think we're directly harming animals," said co-author and SeaDoc Society Director Joe Gaydos, a wildlife veterinarian with the Karen C. Drayer Wildlife Health Center in the UC Davis School of Veterinary Medicine. "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."

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