Using opportunistic sightings to assess the suitability of Important Marine Mammal Areas (IMMAs) for cetacean conservation in the Western Mediterranean Sea

espanolEl Mar Mediterraneo occidental conecta, a traves del Estrecho de Gibraltar, el Oceano Atlantico con el resto del Mediterraneo, siendo un area importante para los cetaceos. Ademas, en el Mediterraneo occidental existen importantes areas de alimentacion como el Santuario de Pelagos y el giro Sur de Baleares. El objetivo principal del presente estudio es evaluar la idoneidad de la delimitacion de las diferentes IMMAs (Areas Importantes para Mamiferos Marinos) descritas en el Mediterraneo occidental, para la conservacion de los cetaceos que habitan en el area de estudio, a traves del analisis de avistamientos oportunistas. Se recogieron 398 avistamientos oportunistas (OS) dentro de algunas IMMAs (46,44%), frente a 459 (53,56%) avistamientos fuera de las IMMAs. Usando un analisis de superficie de tendencia espacial se seleccionaron los OS mas probables (GPOS desde ahora) que aparecen dentro de una IMMA en funcion a su posicion geografica. Se encontraron diferencias significativas entre la frecuencia de GPOS y las esperadas ponderada para la superficie de cada area IMMA. Concretamente el IMMA del Mar de Alboran mostro un numero mayor de GPOS de lo esperado, en comparacion con el IMMA del Mar Mediterraneo, Pendiente y Canon del noroeste mediterraneo que mostro un numero menor de GPOS de lo esperado. EnglishThe Western Mediterranean Sea connects the Atlantic Ocean with the rest of the Mediterranean Sea through the Strait of Gibraltar. The Western Mediterranean Sea is important area for cetaceans and it contains highly productive feeding areas, such as the Pelagos Sanctuary and the South Balearic eddy. The main aim of this study was to assess the suitability of a group of Important Marine Mammal Areas (IMMAs) for the conservation of cetaceans inhabiting this area. There were 398 (46.44%) opportunistic sightings (OS) within a number of IMMAs and 459 (53.56%) sightings outside of IMMAs in this area. Trend surface analysis was used to select the OSs (GPOSs hereafter) most likely to be observed within IMMAs as a function of their geographical position. Significant differences were found between the observed GPOS rate and the expected GPOS rate weighted by the surface area of each IMMA. Specifically, there were more sightings than expected in the Alboran Sea IMMA than in the North West Mediterranean Sea, Slope, and Canyon System IMMA. In the latter area, there were fewer sightings than expected.