Continued increase in the number of black-browed albatrosses (Thalassarche melanophris) at Diego Ramírez, Chile

Abstract

Black-browed albatrosses (Thalassarche melanophris) are killed incidentally in commercial fishing operations. Aerial surveys in 2002 and 2011 revealed the number of black-browed albatrosses at the Diego Ramirez and Ildefonso islands, Chile, increased by 52 and 18 %, respectively. The increases were attributed to reduced mortality in the longline fishery for Patagonian toothfish (Dissostichus eleginoides) following fleet conversion to a new gear configuration with much higher average hook sink rates. A new survey in 2014 revealed the number of black-browed albatrosses at Ildefonso was about the same as in 2011, but the number at Diego Ramirez had increased by a further 29 % (8.8 %/year). The number of grey-headed albatrosses (Thalassarche chrysostoma) at Diego Ramirez also increased, by 23 %, in the same time period. In 2014, Ildefonso held an estimated 54,284 breeding pairs of black-browed albatrosses. The populations of black-browed albatrosses at two more northern sites, the Evangelistas and Leonard islets, stood at 4818 and 545 breeding pairs, respectively. The total number of breeding pairs of both albatross species at Diego could not be determined because not all islands in the archipelago were surveyed.