In the open ocean, healthy killer whales live free of any natural predators -- but in captivity, even the smallest of insects pose a lethal threat to these majestic giants.
According to the Whale and Dolphin Conservation Society (WDCS), new evidence suggests that in recent decades at least two orcas housed at SeaWorld parks perished due to mosquito-borne illness from West Nile and St. Louis encephalitis viruses. The findings raise renewed questions about the appropriateness of keeping large aquatic mammals in such restrictive holding tanks -- which experts say, contributed to the transmission of the diseases.
Courtney Vail, campaigns manager for WDCS, says that killer whales in captivity are prone to spending too much time floating, or "logging", due to the limitations of their enclosures. These unnatural restrictions, and the resulting coping behavior, make orcas in captivity more susceptible to insect bites and the threat of disease:
“We continue to be astonished at the serious information that is being discovered about the condition of orcas in captivity, and that hasn’t yet been shared with the public," says Vail. "I think it is safe to say that no one would have thought of the risks that mosquitoes might pose to orcas in captivity, but considering the amount of time they unnaturally spend at the surface in shallow pools at these facilities, it is yet another deadly and unfortunate consequence of the inadequate conditions inherent to captivity.”
Former SeaWorld trainer, Dr. John Jett:
“Logging was commonly witnessed while I was at SeaWorld, especially at night, which provided a static landing platform for mosquitoes. Free ranging orcas, conversely, are on the move and not exposed to mosquitoes. They don't remain still long enough and mosquitoes are weak fliers, limited to coastal areas. This information is an important introduction to a topic sure to raise eyebrows."
So far, the experts have identified two orca deaths at SeaWorld parks in Orlando and San Antonio resulting from mosquito-borne viruses, though there may be more as several dozen animals remain in captivity throughout the world. The WDCS hopes to raise public awareness about these threats as they advocate for the release of killer whales.