Changes in population size of large Procellariiformes breeding in the French sub-Antarctic islands: potential influence of southern fisheries and particularly long lining

Studies carried out over the past three decades in the French austral territories indicate that most albatross and giant petrel populations have markedly declined. Demographic studies indicate that these declines are mainly the result of increased adult mortality. This high rate of mortality has been suspected to be the result of mortality incurred in long-line fisheries. Satellite tracking studies of breeding birds and band recoveries of non breeding birds indicate that during and outside the breeding season these populations are in contact with long-line fisheries, mainly the pelagic Japanese tuna fishery and in a lesser extent the neritic Dissostichus fishery operating in the Kerguelen EEZ. The decrease in the fishing effort of the Japanese fishery during the recent years has probably resulted in the slow recovery of great albatross population. Long-line fisheries are likely to represent a major threat for long-lived seabirds in the southern ocean, especially the tuna fishery for the Indian Ocean populations. Potential threats from the Kerguelen Dissostichus fishery exist but can be minor if measures to reduce mortality continue to be enforced in the EEZ.