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Understanding seabird distribution patterns to design marine Important Bird Areas (IBAs)

Final Activity Report Summary - MARIBA (Understanding seabird distribution patterns to design marine Important Bird Areas (IBAs))

Marine protected areas (MPAs) represent a promising management tool in agreement with the ecosystem-based management (EBM) principle. However, less than 1 % of the oceans' surface is currently protected and most MPAs are small and restricted to coastal areas, thus overlooking wide-ranging marine organisms which are key components of marine trophic webs (top predators) and useful monitoring tools of the anthropogenic impacts on the marine environment. Among these organisms, seabirds are conspicuous and can be practically studied in a two-dimensional space, thus facilitating the understanding of their habitat use.

MARIBA run in coordination with the initial stages of a pioneering LIFE project which was directed at designing important bird areas at sea (marine IBAs) in Spain, forming a first interdisciplinary step to create MPAs accounting for wide-ranging marine organisms. The main contribution of MARIBA was the study of variables that influenced seabird distribution and behaviour at sea, e.g. chlorophyll, bathymetry, colony location and fishing activity, at different scales, and the development of predictive models to identify key areas for seabirds on the basis of environmental variables. These advances would contribute to identify marine IBAs and properly establish their limits at sea, though work was still in progress. The project used data from satellite-tracking and sea transect-surveys for the analysis of habitat use and a first predictive model was successfully developed for the breeding season of the critically endangered Balearic shearwater, in collaboration with other research institutions.

Important effort was also directed to understanding the influence of fishing activities on seabird distribution patterns and behaviour, since it was a key point for the design of management strategies. We designed and carried out an experimental survey covering different fishing regimes, such as trawling moratoria versus trawling activity, at different periods. The results suggested that seabirds primarily selected their foraging grounds on the basis of habitat features, at medium-scale, and, once in the suitable area, tended to aggregate around trawlers, which was a small-scale process.