Posted on 27-7-2003

Whales May Have Been More Plentiful
By Guy Gugliotta, Washington Post, 25 July 2003

     Scientists may have profoundly underestimated the number of whales that once lived in the North Atlantic Ocean, a controversial finding that could have critical implications for the future of whaling and whale conservation, a new genetic study concludes.

     The gulf between the new estimates and those from existing historical-statistical studies is so vast -- a difference of several hundred thousand animals -- that it has already provoked a spirited debate over scientists' techniques in gathering and analyzing the data.

     "We're suggesting that the oceans can support these populations in the long term, and in fact did," said geneticist Joe Roman, a Harvard University graduate student and co-author of the new study with Stanford biologist Stephen R. Palumbi. "There are all kinds of different views on this, and we knew it was going to be controversial, but this is what the data show."

     Roman and Palumbi analyzed DNA from three species of North Atlantic whales and found the genetic variation to be unexpectedly high in all cases -- a result indicating that before commercial whaling began in the 17th and 18th centuries there was a much larger pool of animals than historical records suggest.

     In fact, the authors report today in the journal Science, their analysis showed that the pre-whaling, or "historic," population of humpback whales in the North Atlantic was 240,000, 12 times as many as the current historical-statistical estimate of 20,000. There are about 10,000 now.

     Roman and Palumbi also estimated the historic population of fin whales at 360,000, nine times more than historical-statistical estimates of 40,000, and the population of minke whales at 265,000, as against statistical estimates of approximately 100,000.

     The findings could play an important role in decisions of the International Whaling Commission, the 51-nation convention that imposed an international moratorium on whaling in 1985 to allow stocks to rebuild after the decimation of the 19th and 20th centuries.

     The commission has agreed that whaling should not be allowed until stocks reach at least 54 percent of historic levels. Under this stipulation, the current North Atlantic humpback population is about 50 percent of historical-statistical estimates, while fins, at 56,000 and minkes at 149,000 have already exceeded the threshold.

     But under the new genetics-based estimates, only the minkes are close to 54 percent. "One of the things that the data tell us is that we have a long way to go for recovery," Roman said in a telephone interview. "Things were vastly different in the relatively recent past. How do we get to that restoration? I don't know."

     Commission Secretary Nicola Grandy did not comment on the new study but noted that "a majority of our members currently don't want to see a return to commercial whaling." And if they did, Grandy said in an interview from the commission's Cambridge, England, headquarters, whaling would be strictly confined to particular species and locations .

     The commission has based its estimates of historic populations on statistical analyses derived from whaling records and logbooks. Before commercial whaling began in the 1600s, humans had no effective way of hunting whales on the high seas, and even during the "Moby Dick" era in the mid-19th century, wooden ships could not handle anything bigger than a 50-ton humpback.

     "Right whales were the favorites, because they were 'right' -- they were slow, coastal and they floated after you killed them," said mathematician and fisheries specialist Doug Butterworth, of South Africa's University of Cape Town.

     "Fin and blue whales were big, fast and would pull you right to the bottom if you killed them," he said. Fin whales weigh 70 tons, while blue whales, which can weigh 120 tons, are the biggest animals that ever lived. Fin whale hunting began only with the advent of steam-driven whalers in the 1880s.

     Estimating historic whale populations in the traditional way is "simple," said Butterworth, a member of the commission's Scientific Committee. "You figure how many whales there are, and add to that how many were caught." The pre-commercial census would be even lower if it accounted for natural reproduction during the whaling years.

     The discrepancy between traditional estimates and those in the new study is so huge that it defies easy reconciliation, added fisheries biologist Timothy D. Smith, of the Commerce Department's Northeast Fisheries Science Center in Woods Hole, Mass. "If there was a secret population somewhere, we don't know where it was," said Smith, another Scientific Committee member. "These guys [whaling captains] went everywhere."

     Roman and Palumbi did their analysis by studying the rate of genetic variation in the mitochondrial DNA, which is inherited only from the mother, of the three whale species, and found a rate of mutation much higher than would be expected from the historical-statistical estimates.

     The authors wrote that "whaling logbooks may be incomplete, intentionally underreported or fail to consider whales that were struck and lost," a judgment Smith called "facile" and "disturbing."

     "If they'd come up with numbers that said twice as many, then maybe we'd start thinking about our methods," Butterworth added. "But when you come up with five-to-10 times as many, then maybe they're the ones who ought to take another look."