Extinction risk assessment of declining wild populations: The case of the southern bluefin tuna

We estimate the extinction probability of a large and decreasing population , the southern bluefin tuna. This tuna was listed as critically endangered by the World Conservation Union (IUCN) in 1996. However, the absolute popul ation size is still large and the extinction probability within the next ha lf century is negligible if the recent population decline rate does not inc rease in the future. IUCN's criterion with respect to the population declin e rate should be linked to the absolute population size, if this is estimat ed. Several methods estimating the probability of extinction conclude that the southern bluefin tuna population will be below 500 mature individuals w ithin the next 100 years and may be listed as vulnerable. These analyses su ggest that extinction risk assessment is useful for management action for t axa that still have large population and are rapidly decreasing.