Projected migrations of southern Indian Ocean albatrosses as a response to climate change
Résumé
Anthropogenic climate change is altering the geographical distribution and regular
movements of species. Highly-mobile pelagic seabirds, such as albatrosses, are particularly
threatened by human activities, such as fisheries bycatch. Predicting the impact
of climate change on how these animals roam the ocean is an important step towards
making informed conservation decisions. In this study, we used a mechanistic model
of migratory movements to predict how the migration of albatross species that breed
in the southern Indian Ocean may change between now and the end of the century.
The model is able to generate non-breeding movement patterns of albatrosses that
correspond to empirical patterns from tracking data, thus providing confidence in the
ability of the model to make future predictions. We projected the model using environmental
conditions for 2100 based on a scenario assuming high emissions (IPCC
RCP 8.5). Overall, we found very little projected change in the non-breeding distribution
of albatrosses compared to the present. Some change, however, is predicted for
large albatrosses, which, due to their size, are more affected by wind, and are projected
to migrate further eastwards in the future scenario. These results contrast with previous
analyses focusing on the breeding distribution that used statistical modelling, such as
habitat and species distributions models, and predicted poleward shifts in geographical
distributions of various seabird species including albatrosses. Therefore, it highlights
the need for formal comparison of predicted changes in distribution during different
phases of the annual cycle of the albatrosses and/or integration of the different
approaches. Our analysis also predicts that the overlap of albatrosses with Regional
Fisheries Management Organisations (RFMOs) during the non-breeding season will
remain similar in 2100 compared to today. This implies that large-scale by-catch mitigation
measures implemented through fisheries management organisations will remain
important over the next hundred years of climate change.