Good whale hunting: two tantalizing Russian reports take the author on a quest to the Antarctic, in search of two previously unrecognized kinds of killer whale

Natural History, Dec, 2003 by Robert L. Pitman

They always remind me of witch's hats--a little bit of Halloween in the winter wonderland. Looking across a flat plain of frozen Antarctic sea ice, I watch as a herd of killer whales swims along a lead--a long, narrow crack in the six-foot-thick ice. The fins of the males are black isosceles triangles, five feet tall, and they look like a band of trick-or-treaters coming our way. I am on board the U.S. Coast Guard icebreaker Polar Star as it back-and-rams the frozen ocean to open up a fourteen-mile-long channel into McMurdo Station, fifty feet at a whack. The National Science Foundation has offered me a bunk on board the vessel while I study the killer whales that inhabit the pack ice of the southern Ross Sea.

In the early 1980s, whalers from the former Soviet Union, presumably in the mood for some new product testing, slaughtered more than 900 Antarctic killer whales in one season. Workmen on the flensing deck of the factory ships, where the blubber and meat is stripped off the animals, quickly realized that two quite different kinds of killer whale were being hauled up the slipway for processing. The differences were so striking that two groups of Soviet investigators independently described new species of killer whale from the Soviet catch data--though it is not clear from their accounts whether they were describing the same, or different, new species.

In any event, one group's description was too vague, and a holotype, or museum reference specimen, was not designated, so the description has to be scientifically ignored. The other description, however, by Alfred Berzin and Vladimir Vladimirov, both cetacean biologists at the Pacific Research Institute of Fisheries and Oceanography in Vladivostok, Russia, provided some fairly solid evidence that there might be two species of killer whale in Antarctica. (Unfortunately, although Berzin and Vladimirov designated a holotype specimen, it has subsequently been discarded.) One species, of course, is the familiar denizen of Sea-World, a large black-and-white form that lives throughout the world's oceans but does not penetrate into the Antarctic ice. It travels in herds of between ten and twenty animals and feeds almost exclusively on marine mammals, particularly Antarctic minke whales (Balaenoptera bonaerensis). This form is likely just a summer visitor to Antarctica.

Berzin and Vladimirov reported that the second form, which they provided a name for--Orcinus glacialis--in their belief that the species was new to science, lives mainly in the pack ice, where it may be a year-round resident. It occurs, they said, in herds that sometimes number in the hundreds of individuals. The animal is between three and rive feet shorter than O. orca, with markings that are yellowish in color instead of white, and feeds almost exclusively on fish. The yellow coloration is presumed to be from an infestation of diatoms. Caused by microscopic phytoplankton that occur in polar waters and on the underside of ice, the coloration is a characteristic of all forms of pack-ice killer whales, but not of O. orca. The pack-ice animal also has much smaller teeth than O. orca, which may be related to its diet of fish. Although the Russian description of O. glacialis is in many ways convincing, most cetacean biologists have not accepted the validity of a second species, much less a third one (the species described so vaguely by the second group of Soviet investigators). Yet the evidence is tantalizing enough that I have come to the Antarctic Ocean to see for myself.

As the Polar Star sits motionless at the head of the channel we have just created, killer whales that were swimming along the edge of the pack ice are now moving toward us through the broken ice that has filled in behind the ship. As they enter the dense pack ice, their heads start sprouting up through the shattered ice like giant black-and-white tulips. They are "spyhopping": hovering above the surface for a second or two, where they seem to be eyeing our vessel and the ice in between us and them, and then easing straight back down into the water.

It dawns on us that the entire herd of thirty or so animals are leap-frogging through the pack ice and moving toward the stern of our ship, seemingly interested in the pool of open water that our prop wash has created. Sometimes individuals pop up several times in the same spot, apparently looking ahead for the next open water before they proceed. Their heads jut high out of the water, maybe six feet or so, and they crane their necks to scan the surface in search of the next breathing hole. Getting stuck under the ice would spell certain death for these air-breathers, and they need to carefully plan their moves.

As they close in around us, we notice another intriguing behavior: just before the whales break the surface, the sea boils vigorously and a perfect circle of clear water opens up above them. Most of the broken ice behind the ship is tightly packed, and the shards are hard and often sharp. The adult whales are forcefully exhaling just before surfacing, opening up a breathing space several feet across so they won't cut or scrape their sensitive skin on the ice debris. Whale calves also surface in the ring of open water, right next to their mothers.