Hawaii's Marine Homebodies
Some time in the distant past -- perhaps thousands of years ago, though scientists can’t say yet for sure -- a group of false killer whales quit roaming the open ocean and made the waters around Hawaii their home. Their descendents, now known as Hawaiian insular false killer whales, have remained separate for so long that the roughly 150 members of their population are genetically distinct from other Pseudorca crassidens -- and at risk of extinction.
In November, the National Oceanic and Atmospheric Administration recommended Hawaiian insular false killer whales for protection under the Endangered Species Act, noting that because they’re slow to mature and live long past their ability to reproduce, only about 46 of them are currently able to breed.
False killer whales are classified in the genus Pseudorca because their skull and teeth are similar to orcas’, but they don’t look at all like Shamu. Both species are members of the oceanic dolphin family, but false killer whales appear more dolphinlike -- smaller and slimmer than orcas, and entirely black or dark gray. Most live untethered in tropical and subtropical waters around the world, but Hawaiians think of insular false killer whales as "kamaainas," children of the land or long-term residents.
Pseudorca crassidens seem to have an affinity for humans in return. The whales often live into their sixties and possess complex social lives. They hunt together and share their prey, passing a fish around before any one of them takes a bite. The communal behavior seems to have "a symbolic or ritualistic significance" as "a way of reaffirming their social bonds," says Robin Baird, a biologist for the Cascadia Research Collective, an Olympia, Washington, nonprofit that specializes in studying threatened marine mammals. Though they try to keep their catches away from competitors such as dolphins, on several occasions, they’ve offered their fish to boaters and divers. "It’s really quite an astounding behavior," Baird says. "When they interact with humans in that way they must recognize that we’re similar enough in terms of our social behavior."
But, ironically, it’s the similarities we share with the whales that also make us dangerous to them. We eat the same kinds of fish they do, like mahi-mahi and tuna, so fisherman often hook them by mistake and commercial harvesting depletes their food sources. Because of their longevity, they also accumulate decades´worth of man-made pollutants such as DDT, PCBs, and flame retardants, which can damage their immune systems.
As the only false killer whale population ever known to adopt an island territory -- which they may have done because fish were more plentiful near the islands than in the open ocean -- the Hawaiian insulars can’t escape local threats as easily as whales that stray farther from shore. (Genetic defects from inbreeding pose an additional a risk, as their numbers are so few.) Baird argues that the whales’ plight and proximity should alarm us on our own behalf as well as theirs. After all, the environmental toxins and overfishing that are harming the whales are hurting us, too. But protecting Hawaiian insular false killer whales is also about preserving a unique and potentially ancient cetacean society. The reason they live near Hawaii and nowhere else "really comes down to their culture," Baird says. "That’s their home."
