Orcas face a variety of deadly threats—many stemming from human interactions, according to pathology reports on more than 50 killer whales stranded over nearly a decade in the northeast Pacific and Hawaii.

A study analyzing the reports in PLOS ONE indicates that understanding and being aware of each threat is critical for managing and conserving killer whale populations. It also presents a baseline understanding of orca health.

The whales include those from healthy populations as well as endangered species, such as the southern resident whales regularly sighted off the coasts of British Columbia, Washington, and Oregon.

Scientists determined the causes of death for 42% of 53 whales stranded between 2004 and 2013. 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.

Despite the absence of a single common cause of death, the study found a common theme: Human-caused deaths occurred in every age class—from juveniles to subadults and adults.

“Nobody likes to think we’re directly harming animals,” says Joe Gaydos, a wildlife veterinarian with the Karen C. Drayer Wildlife Health Center in the School of Veterinary Medicine at the University of California, Davis and director of the SeaDoc Society.

“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.”

Read the full article about the endangerment of Orca Whales by Kat Kerlin at Futurity.