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Right Now | Cetacean Census

Whales Aplenty

November-December 2003

The hunters launched in mid August from Iceland and steamed into the North Atlantic. There were three ships, each tracing a different track across the cold gray water, each outfitted to kill and dissect their enormous prey. After a day's sail the first boat found its quarry, and with the blast of a harpoon cannon, Iceland resumed whaling for the first time in more than a decade.

The hunt drew protests from around the world and rekindled debate on the future of whaling. Some species are recovering from relentless commercial hunting during the nineteenth century, when whale oil, not petroleum, illuminated the night and whale meat, blubber, and bone powered a robust international trade. Iceland, Japan, and Norway cite these increased populations while lobbying to end a 17-year-old moratorium on most types of whaling. But in July, just weeks before the Icelandic hunt, researchers from Harvard and Stanford published a study in Science showing that figures used to gauge the size of whale populations and guide whaling regulations may be grossly inaccurate. In fact, the study suggests that the ocean may once have supported more whales than anyone imagined possible.

To better understand whale populations before commercial whaling began, Joseph Roman, a newly minted Ph.D. in biology, and Stanford's Steven R. Palumbi, formerly a biology professor (and Roman's adviser) at Harvard, probed mitochondrial DNA samples of humpback, fin, and minke whales from the North Atlantic. DNA contains a record of genetic mutations that provides a sort of timeline to a species' history. The researchers expected to find a low level of genetic diversity, which would indicate mutations accumulating slowly over time in populations that were relatively small. Instead, Roman and Palumbi found that, despite small modern populations, the whales showed remarkably high genetic diversity, with numerous mutations that could have accumulated only from huge earlier populations. Prewhaling numbers were "strikingly large," Roman says. "Certainly the genetic data suggest that we decimated whale populations to a far greater degree than we thought."

Scientists estimate that about 10,000 humpback, 56,000 fin, and 149,000 minke whales now cruise the North Atlantic. Conventional estimates have put the prewhaling humpback population at around 20,000; fin whales are said to have numbered between 30,000 and 50,000 individuals. But Roman and Palumbi concluded that up to 240,000 humpbacks and 360,000 fins—about 12 times as many as estimated—lived in the North Atlantic before the harpoons started flying. Past minke whale populations were also underestimated by several thousand individuals, the researchers say.

Such huge numerical differences have enormous political implications. Traditionally, scientists estimated prewhaling populations using historical data from ships' logs and captains' diaries. The International Whaling Commission (IWC), the London-based body that regulates whaling for its 51 member states, used these estimates to shape a 1986 treaty banning commercial whaling. (Iceland, a member of the IWC, resumed the hunt under a special exemption that allows whaling for "scientific" purposes.)

According to the treaty, member nations agreed to ban whaling until whale populations rebound to 54 percent of their prewhaling levels. Some species are approaching that mark, but given the new data, Palumbi has said that certain whale populations may not reach the IWC's 54-percent threshold for 70 years or more—far longer than originally predicted. "Humpback whales are certainly not ready for hunting," says Roman. "Neither are fin whales, for that matter. I think it probably is too early to start hunting commercially again. I think we're forgetting now how close whales came to extinction."

Critics charge that the new estimates are far too high. Others doubt historical records could be so imprecise. Roman anticipated such criticism: he and Palumbi used very conservative methods in their calculations. As for the accuracy of the logbooks, Roman says that they offer only pieces of the puzzle: "The big question is, how much whaling was done before the records were kept? How many records were lost?" The next population studies, he says, will use refined genetic techniques, and they'll revisit the dusty records themselves. "I think there's a future looking at the logbooks again," he explains. "A lot of these species, with the exception of humpbacks, haven't really been looked at.''

Roman doesn't predict the return of industrial-strength whaling. While cash-hungry Yankee fleets once nearly annihilated many species, most nations have since lost their taste for whale blubber. The huge mammals now fuel a different industry: tourism. (In Iceland, up to one out of four tourists arrives to go whale watching.) Roman says their study provides a snapshot of an ocean from long ago that he hopes will offer a vision for the future. "The history of whaling really is about exploiting and moving on. This is the way it happened for a lot of other species, too,'' he says. "When we go out on a whale watch, it's hard to imagine what the ocean looked like a few hundred years ago...and how much better a place it could be given good management.''

~Neil Shea

 

Joseph Roman e-mail address: [email protected]