Diet of Black-browed Thalassarche melanophrys and Atlantic Yellow-nosed T. chlororhynchos albatrosses and White-chinned Procellaria aequinoctialis and Spectacled P. conspicillata Petrels off southern Brazil

摘要

The diet of the Black-browed Albatross Thalassarche melanophrys, Atlantic Yellow-nosed Albatross T. chlororhynchos, White-chinned Petrel Procellaria aequinoctialis and Spectacled Petrel P. conspicillata were studied by analyzing the contents of digestive tracts of birds found washed ashore or incidentally caught by pelagic longline fisheries off southern Brazil between 1994 and 2004. Cephalopod beaks, fish otoliths and eye lenses were dominant in the digestive tracts of birds. About 90% of the food items of petrels were in the gizzard and were mainly cephalopod beaks, which are resistant to digestion. Among anthropogenic items ingested, plastics were the most frequent and most numerous. Cephalopods predominated in the diet of White-chinned and Spectacled Petrels, mainly squid from the family Histioteuthidae. Fish had greater importance in the diet of both albatross species. Demersal fish occurred in the diet of albatrosses and the White-chinned Petrel. Coastal fish distributed over the continental shelf were found in a higher number and diversity in beached birds than in birds killed in longline fisheries. Cephalopods predominated in both number and diversity in the diet of longline-caught birds, mainly sub-Antarctic and subtropical species. Approximately 40% of this diet was composed of fish and cephalopods that were probably discarded from fisheries, evidence of a strong interaction between these birds and fisheries in southern Brazil.