Risks of decline and extinction of the endangered Amsterdam albatross and the projected impact of long-line fisheries

The Amsterdam albatross (Diomedea amsterdamensis) is one of the rarest bird species of world avifauna, consisting of a single population in the upland plateau of Amsterdam Island (SE Indian Ocean). All breeding birds of the p opulation are today banded and a monitoring program involving mark-recaptur e procedures has been carried out continuously over the past 16 years. We p resent the first estimate of risk of decline for the Amsterdam albatross us ing a stochastic matrix population model, and evaluate the extent to which the measurement errors in demographic estimates may affect the baseline con servation assessment. We also estimate the potential effect that resumption of long-line fisheries in the vicinity of Amsterdam Island (one the allege d causes for its low numbers in the recent past) may have on the persistenc e of this population. Our results indicate that, in the absence of any impa ct of long-line fisheries, the Amsterdam albatross is unlikely to experienc e a decline larger than 20% of the current population abundance over the ne xt 50 years. Our results point out the difficulty to assess with certainty the extinction risk of small populations despite the availability of long t erm data on their demography. They suggest that a very cautious approach sh ould be taken for the preservation of small populations of long-lived speci es that cannot sustain any level of incidental by-catch. Any new long-line fishery resuming in the foraging range of the Amsterdam albatross, but espe cially close to Amsterdam Island, may rapidly put this species at risk of e xtinction. (C) 2001 Elsevier Science Ltd. All rights reserved.