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The Tristan Albatross Diomedea dabbenena qualifies as globally Critically Endangered due to its extremely small breeding range, population declines and a projected rapid population decline over the next three generations. The species occurs in South African waters and, by virtue of its global status, the species is listed as regionally Critically Endangered.
Tristan Albatrosses breed only at Inaccessible and Gough islands (part of the United Kingdom’s Overseas Territory of St Helena, Ascension and Tristan da Cunha) in the central southern Atlantic Ocean (Cooper 2000a). The Inaccessible Island colony has produced less than one chick per year since at least the 1980s (Ryan 2005a). Distribution at sea is little known due to confusion with Wandering Albatross although satellite-tracking data from 38 individuals indicated that during the breeding season the species is largely restricted to the southern Atlantic Ocean (Cuthbert et al. 2005). More recent tracking data shows adults moving eastwards into Australasian waters, and also into lower latitudes in the East Atlantic, as far as southern Angola (Reid et al. 2013). A small proportion of these are in South African waters at any one time. Regionally, the Tristan Albatross overlaps with the ranges of the Indian Ocean Tuna Commission, Convention for the Conservation of Southern Bluefin Tuna, the International Commission for the Conservation of Atlantic Tunas and South East Atlantic Fisheries Organisation.
The annual breeding population on Gough Island is estimated to be 1 747 pairs, equivalent to 7 100 individuals or 4 700 mature individuals (ACAP 2009a). The number of birds present in South African waters is unknown. The confidence in this population estimate is high.
The population on Gough is decreasing at a rate of 2.85% per year, and mean chick production is decreasing annually by 1% (Wanless 2007, Wanless et al. 2009). As a result, a decrease of = 80% over the next three generations in the global population is expected (BirdLife International 2014a). The confidence in this population trend estimate is high.
The primary threat is from interaction with longline fishing vessels leading to drownings (Tuck et al. 2003), mainly off South America (Cuthbert et al. 2004) with only a few individuals having been killed on longlines off South Africa (Petersen et al. 2009a). A secondary, but still significant, threat is from predation by introduced House Mice Mus musculus on Tristan Albatross chicks which accounts for up to 50% of nesting failures by the Tristan Albatross (Wanless, t al. 2007). Plastic remains are occasionally seen in stomach contents of chicks on Gough Island (RM Wanless pers. obs.)
The Conservation of Native Organisms and Natural Habitats (Tristan da Cunha) Ordinance of 2006 and the Gough and Inaccessible Islands World Heritage Site Management Plan of 2010 and its Appendix A2 of 2012 set out measures providing protection to the species (Cooper 2000a). Together Gough and Inaccessible Islands and their 12-nautical mile territorial waters form a World Heritage Site, and separately both are Ramsar Sites of International Importance since 2008. Both islands and their territorial waters are nature reserves in terms of the 2006 ordinance. Strong local action in South African longline fisheries is reducing incidental catch of albatrosses. This needs to be transferred internationally to all longline vessels operating within the foraging range of this species, especially off the Atlantic Coast of South America within the species’ range. South Africa, along with the United Kingdom, is listed as a Principal Range State for the species by the Agreement on the Conservation of Albatrosses and Petrels (ACAP 2009a).
Eradication of House Mice on Gough Island must be seen as the very highest priority. At sea-threats need to be reduced via implementation of bycatch mitigation measures. Improvement in the identification by bycatch assessors is required. The strengthening of mandatory seabird conservation measures at the International Commission for the Conservation of Atlantic Tuna and the Indian Ocean Tuna Commission have provided a good basis for improved mitigation of seabird bycatch in both ocean basins. Additionally, both observer programmes should have increased coverage of longline efforts in waters south of 25°S, and observer data reporting requirements and accessibility should be improved.
* The distribution of immature and non-breeding birds and overlap with fishing operations needs to be ascertained, and mitigation measures enforced.
* Ongoing monitoring of population trends or changes in adult and juvenile survival.