Contribution of fishery discards to the diet of the Black‑browed albatross (Thalassarche melanophris) during the non‑breeding season: an assessment through stable isotope analysis

Black-browed albatrosses (Thalassarche melanophris) disperse over the Argentinean Continental Shelf and neighboring waters during their non-breeding season. It is one of the most frequent seabirds attending fishing vessels and also the most common Procellariform in the bycatch of longliners and trawlers in the area. Understanding the use of fishery discards by this species is an important issue when assessing the potential effect of strategic discard management in decreasing the abundance, interactions, and mitigating mortality. In the present study, we analyzed carbon and nitrogen stable isotope compositions in the blood of Black-browed albatrosses to assess the relative contribution of discards from different fisheries to the diet of this species in winter. Samples were obtained in winter 2011 from fishing vessels operating between 41–43°S and 57–59°W. No sex differences in δ13C and δ15N were observed. Results indicate that during their nonbreeding season, isotopic signatures of Black-browed albatrosses are closer to discards and offal generated by fisheries and in particular by trawlers. The large fishing effort of trawl fisheries in Argentina highlights the urgency of an exhaustive analysis to find practical and effective ways to reduce the number of seabirds attending trawlers.Fil: Mariano y Jelicich, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Copello, Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Seco Pon, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Favero, Marco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Sex-biased incidental mortality of albatrosses and petrels in longline fisheries: differential distributions at sea or differential access to baits mediated by sexual size dimorphism?

Skewed adult sex ratio (ASR) has been proposed as a common pattern in birds, frequently biased towards males and with larger biases in globally threatened species. In albatrosses and petrels, it has been suggested that differential mortality of one gender in fisheries is caused either by sexual size dimorphism giving males a competitive advantage, which allows more access of the larger sex (i.e. males) to discards and/or baits, or to at sea segregation of sexes. Here, we tested these hypotheses by determining ASRs in albatrosses and petrels trapped at sea when attending longline fishing vessels for discards in the southwestern Atlantic Ocean, and searched in the literature for patterns in ASR in albatrosses and petrels killed by fisheries in this area and elsewhere. We show that skewed ASR is common in albatrosses and petrels in the community attending vessels for discards, confirming results found for birds in general. There was no correlation between skewed ASR and conservation status, or between ASR and sexual size dimorphism. Our review of the sex of birds incidentally killed in fisheries found skewed ASR toward males, females or parity to be equally reported. Thus, sexual dimorphism in size does not explain skewed ASR in the community we sampled or in incidental captures in fisheries in the review. Differential at-sea distribution of sexes appears to be a better explanation of the patterns found in the community sampled at sea as well as skewed ASR in seabird fatalities, particularly distant from breeding areas

Seascape modeling of southern giant petrels from Patagonia during different life-cycles

Presence-only models such as Ecological Niche Factor Analysis (ENFA) compare distributions of environmental variables and species, generating habitat suitability (HS) maps. Here, we determined the factors affecting distribution of southern giant petrels (SGP) from northern Patagonian colonies (Isla Arce: 45° 00ʹS; 65°29′W, and Isla Gran Robredo: 45°08ʹS; 66°03′W) using ENFA, improving estimates of their potential year-round feeding habitats. Data on movements of 17 adult and 9 first-year juvenile SGP were gathered using satellite telemetry. Model eco-geographical variables (EGV) overlapped the tracked animals. The resulting HS maps included most of the tracking locations along the Argentinean Shelf and reflected characteristics that congregate procellariiformes elsewhere. Wind conditions and primary productivity shaped foraging HS of petrels over the year. However, different EGVs influenced this population differently depending on the requirements of their life stage. For example, juveniles showed high marginality (values of EGVs different from the mean values available). Breeding adults´ HS was determined by a small range of values within those available, showing high specializations. Contrarily, wintering petrels showed plasticity in the selection of their foraging environments being distribution of fisheries one of the variables influencing their distribution. This study highlights the importance of the Argentinean Shelf for conservation of the marine environment.Fil: Blanco, Gabriela Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Sanchez Carnero, Noela Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Pisoni, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Quintana, Flavio Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin