Population decline

Page - December 20, 2006
When the International Whaling Commission was formed in 1946, its preamble noted that, "The history of whaling has seen overfishing of one area after another and of one species of whale after another to such a degree that it is essential to protect all species of whales from further overfishing".

Southern Ocean: The Yushin Maru catcher ship of the Japanese whaling fleet injures a whale with its first harpoon attempt, and takes a further three harpoon shots before finally killing the badly injured fleeing whale. Finally they drowned the mammal beneath the harpoon deck of the ship to kill it.

But, despite this clear recognition of the problem, the International Whaling Commission (IWC) was unable to stop it, instead presiding over the decimation of species after species - until the moratorium was finally put in place in 1986. It is still not known if some species will ever recover, even after decades of protection.

This devastation happened because the reproductive rate of whales is low and the monetary value of individual whales was high. Given this, it might seem sensible to you and me for whalers to strictly limit their catches in order to secure a future for their industry, but a short-sighted economic reality meant that whalers tended to catch as much as they could, as quickly as they could.

The blue whales of the Antarctic are still at less than 1 percent of their original abundance despite over 40 years of complete protection. Some populations of whales are recovering but some are not.

Only one population, the East Pacific grey whale, is thought to be near its original abundance but the closely related West Pacific grey whale population is the most endangered in the world hovering on the edge of extinction with just over 100 remaining - and this is now under threat from oil exploration activities.

The number of Antarctic whales is less than 10 percent of what it was before whaling began.

DNA evidence shows that the impact of commercial whaling may be even worse than previously thought. Most estimates of historic whale population size have been extrapolated from old whaling figures, but this method is often very inaccurate, argues marine biologist Steve Palumbi of Stanford University's Hopkins Marine Station in California, USA.

In 2003 Palumbi and his colleagues used DNA samples to estimate that humpback whales could have numbered 1.5 million prior to the onset of commercial whaling in the 1800s.

That number dwarfs the figure of 100,000 previously accepted by the IWC based on 19th century whaling records. Humpback whales currently number only 20,000.

Japanese delegates to the IWC constantly refer to a 1990 estimate of the Antarctic minke population of 760,000. But the IWC withdrew that figure in 2000 because recent surveys found far fewer minke whales.

The new estimates are half the size in every area that has been re-surveyed. The IWC's scientists do not understand the reasons for this and so far have not been able to agree a new estimate.

It is still not known if some species will ever recover, even after decades of protection.