Conserving Cuvier’s beaked whales in the Alboran Sea (SW Mediterranean): Identification of high density areas to be avoided by intense man-made sound

Abstract

Links between atypical mass strandings of beaked whales and military manoeuvres have been demonstrated in several parts of the Mediterranean, including the Alboran Sea. Herein, information on the distribution and abundance of Cuvier’s beaked whales is presented for the Alboran Sea. Such information is of great importance to allow the impacts of mass strandings, entanglements, etc. to be put in a population context and to highlight the most important areas for this species which may be focus for conservation action. Data used for these analyses come from two sources: summers 2008–2009 on board the vessel Alliance; and 1992–2009 surveys under the umbrella of the NGO Alnitak. A detection function was obtained using distance sampling methods and density surface modeling was undertaken. Availability bias correction factors were estimated for different platforms and vessel speeds and applied during the spatial modeling exercise. The final estimate of density (in animals/km2) corrected for the availability bias was 0.0054 (CV=22%). Based on these results, and a comparison with estimates from elsewhere, it is clear that the Alboran Sea supports one of the highest densities of Cuvier’s beaked whales in the world. This information and the proposed management measures are being used by the Spanish Ministry for Agriculture, Food and Environment to assess the possibility of increasing the level of protection of this species by either to promote a proposal for a Marine Protected Area designation or to include Cuvier’s beaked whales in the Spanish catalogue of threatened species in the “Vulnerable” category.