Abstract: Incidental capture of seabirds in longline fishing gear is a central issue in the conservation of many long-lived marine species. Despite growing evidence of climate-induced effects on population trends of long-lived species, climate change remains generally overlooked in most risk assessments of seabirds. Because variation in climate may interact with the detrimental effects of bycatch, considering climate is of great importance, especially in the context of ongoing global warming. This paper examines the combined effects of bycatch and climate change on the persistence of one of the worlds rarest birds, the Amsterdam Albatross Diomedea amsterdamensis, which has a single population in the upland plateau of Amsterdam Island (Southeast Indian Ocean). Using continuous monitoring from 1983 onwards, we first estimated the relationship between climate and the species demographic parameters. We then built a stochastic matrix population model to estimate the population growth rate and the probability that the population declines below the level recorded in 1983 of nine breeding pairs under different scenarios involving the joint effects of additional mortality caused by longline fisheries and climate change. The results suggest that the demography of the Amsterdam Albatross is influenced by climate in both breeding and wintering grounds and that these relationships may to some extent compensate for the impact of additive bycatch mortality. However, these compensatory effects would be negligible if the annual additional mortality exceeds around six individuals per year, suggesting that the resumption of longline fishery in the foraging range of the Amsterdam Albatross would rapidly put this species at risk of extinction.

Abstract: Eurocold meeting

Abstract: The development of biologging techniques has been instrumental in studying the behaviour of wild animals and interpreting it with respect to the bio-physical features of their habi- tat. Light-based geolocation currently appears to be the only technique suitable for the study of far- ranging small species, particularly marine species, over long periods, but it provides locations with low precision. In this study, we sought to improve the exploitation of these data. Specifically, the goals were to (1) correct rather than reject estimates, especially during equinox periods, (2) perform repro- ducible time-saving routine analyses, and (3) determine the spatial likelihood of the estimations to adapt inferences on habitat use by the population. We therefore applied an existing data-processing method based on spatial template fitting, using Markov Chain Monte Carlo and state-space model- ling (Kalman filter) improved by a facultative sea surface temperature-matching procedure and a land mask. The main functions used for geolocation are grouped under the R package TripEstima- tion, freely available online. We focused on a typical example of animal movement that at present can only be ethically obtained from light-based geolocation. The method made it possible to estimate realistic positions during equinox periods and to routinely process the 12 available datasets. We thus obtained the most probable location for each sunrise/sunset as well as the posterior distribution around each estimated location, allowing an intuitive habitat use investigation at a scale of 100 km. This paper describes the method used and provides the complete and comprehensively annotated commands required for its use.