NZ hits back at whaling claims

By SIMON COLLINS

New Zealand researchers have hit back at Japanese claims that the world's whale population has increased enough to resume whaling.

Japan is arguing at the International Whaling Commission meeting in Italy that the ban can now be lifted because whale numbers have recovered. It is offering vast financial aid to small countries in return for votes backing a return to whaling.

But work by Auckland University's Professor Scott Baker suggests that whale numbers are nowhere near the level needed to sustain whaling.

His team is using new genetic techniques to work out the likely numbers of each whale species before commercial whaling began on a global scale in the 18th century.

The researchers' estimates suggest that numbers for most species are still at most only 10 to 20 per cent of the pre-whaling levels.

The industry peaked in the years just before and after World War II and ended in New Zealand in the 1960s because whales had almost disappeared from the country's coasts.

A global whaling ban was imposed in 1986 and Japan is using promises of new airports, hospitals and other aid projects to induce vulnerable countries such as Tuvalu, Palau and Mongolia to vote to lift the ban.

Observers believe it may get a slim majority of just over half of the IWC's 57 members this week - not enough to scuttle the ban because a 75 per cent majority is required to overturn it. But a simple majority will give Japan and its allies control of the IWC's research.

Dr Baker's Auckland laboratory is one of the world's leading centres of non-IWC research on whales and dolphins. Its 12 researchers include doctoral students from New Zealand, South America and Europe who work with a computer modelling team led by Professor Allen Rodrigo.

The team's genetic technique for estimating past whale numbers, funded by a $580,000 Marsden Fund grant, involves measuring the extent of genetic variation in existing whales of each species, working back from that to estimate the population low-point in the last century, and then back a further 200 years or so to its likely maximum.

"Genetic diversity is a function of the size of a population over a long period. Large populations tend to have a lot of diversity," Dr Baker said.

Whales have five to 10 times as much genetic diversity as humans, indicating that they had a large, stable population for millions of years. They broke away from their nearest evolutionary relative, the hippopotamus, almost 60 million years ago, whereas humans diverged from other ape-like hominids a mere 200,000 years ago.

The southern right whale, once common off the New Zealand coast, dropped from a maximum population of between 60,000 and 150,000 in the 18th century to a low-point of around 120, or just 60 females, in the 1920s, judging by mitochondrial DNA passed down through the mother.

At such low numbers, Dr Baker said, many whales would not have been able to find mates. Recovery has therefore been slow, to an estimated 7500 southern right whales today. If the whaling ban remains, he estimates that some species will recover to pre-whaling levels in 50 to 100 years.