Boost for tiger conservation hopes

17 April 2008 12:00am

The discovery that many tigers in zoos, circuses and private homes around the world are "pure" breeds could boost efforts to conserve dwindling wild populations, researchers have said.

A new study to assess the ancestry of captive tigers found many "generic" animals were in fact pure-bred subspecies - and have genetic diversity no longer found in nature.

The new method of assessment could increase the number of tigers in captivity which are suitable for conservation breeding programmes, the scientists writing in Current Biology said.

Tigers are facing extinction in the wild, with numbers plummeting from more than 100,000 in the 1900s to as few as 3,000 last year. But there are 15,000 to 20,000 tigers in captivity, outnumbering their wild relatives by as much as seven to one, the researchers said.

Despite these healthy numbers, only a small proportion - around 1,000 - are in co-ordinated breeding programmes that aim to preserve the genetic variability that matches the geographic and subspecies groups.

The rest are of hybrid or unknown origin and are kept in zoos, farms, breeding facilities, circuses and private homes.

Using genetic analysis of a sample of 105 tigers, the researchers assigned 49 of them (47%) to one of five subspecies - the Bengal, Sumatran, Indochinese, Amur and Malayan - while the rest were mixed.

The scientists said the percentage of "verified subspecies ancestry" (VSA) tigers may be an overestimate of the captive tiger population as a whole.

But, the researchers said: "If 14-23% of the over 15,000 existing captive tigers would prove to be VSA, the number of tigers with pure subspecies heritage available for conservation consideration would considerably increase."

The researchers said the findings meant the captive tigers could be included in comprehensive conservation schemes to boost population sizes and genetic diversity of the species.

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