southern skuas (up to 500 pairs), Tristan thrushes, Wilkins's buntings and Nightingale buntings. The nearby islands of Gough and Inaccessible Island have been recognised as Wetlands of International Importance under the Ramsar Convention. Aquatic biodiversity The islanders of Tristan da Cunha depend on the fish resource to a large extent for food and for bait for the local rock lobster industry. Approximately 61.5 tons of linefish are harvested each year for these purposes. The insular nature of the island ecosystem renders it vulnerable to over-exploitation from commercial fishing operations. Most of the fish species are bound to the islands for the completion of their life cycles; hence, the populations are more or less isolated and not supplemented by recruits from outside of the system. References Islands of Tristan da Cunha Uninhabited islands of Saint Helena, Ascension and Tristan da Cunha Volcanoes of Tristan da Cunha Important Bird Areas of Saint Helena Seabird colonies