The status and conservation of Antarctic seals and seabirds: A review
Present threats to Antarctic seabirds and seals when ashore include disturbance and habitat destruction (some directly caused by humans; most through the introduction of rabbits and other grazers; also seal damage to seabird habitats) and serious predation by introduced rats and cats at sub-Antarctic islands. In the marine environment threats are posed by pesticides (widespread but at low levels), pollution (mainly a potential problem associated with oil exploration), incidental takes (trivial now, except perhaps for some albatrosses) and competition with commercial fisheries, which is reviewed in detail. Even in areas where harvesting of fish may be exceeding sustainable yield, predator-prey interaction data are inadequate to assess the level, or significance, of the effect on predators. Present krill harvests are small but likely to increase, especially in favoured areas; species of potential vulnerability are noted. Existing legislation offers excellent protection for wildlife, but formally protected areas by no means cover the major breeding concentrations of seabirds and especially seals in all sectors and zones. There is a need for a comprehensive review, which in some areas will require extensive survey work. Programmes for the control and elimination of alien predators need proper planning and major support. Marine reserves may be of limited benefit to pelagic seals and seabirds, and further research in some key areas is needed. Realistic environmental impact assessments will require more detailed information on predator distribution and movements than is available now; appropriate surveys and research need starting. Sensitive management of marine fisheries is difficult with the present level of quantitative data on predator-prey interactions (though this is better than in many other pelagic systems). Difficulties in monitoring aspects of predator biology as indices of the state of prey stocks are reviewed.