Cetacean-fishery interactions in Galicia (NW Spain): results and management implications of a face-to-face interview survey of local fishers

Abstract

Galicia(NWSpain)isanimportantfishingregionwithahighpotentialforcetacean–fisheryinteractions.Cetaceandepredationoncatch and damage to fishing gearcan potentially lead to substantial economic loss for fishers, while cetacean bycatchraises conservationconcerns.Withtheaimofgatheringinformationonthetypesandscaleofinteractionsandofsuggestingpossiblemanagementstrategies,we conducted face-to-face interviews with fishers in local fishing harbours, in particular to identify specific problematic interactions and to quantify the level of economic loss and bycatch rates associated with these interactions. We found that cetacean–fishery interactions are frequent, although damage to catch and fishing gear by cetaceans was mostly reported as small. Nevertheless, substantial economic losscanresultfromcommonbottlenosedolphins(Tursiopstruncatus)damagingcoastalgillnetsandfromshort-beakedcommondolphins (Delphinusdelphis)scatteringfishinpurse-seinefisheries.Cetaceanbycatchmortalitywasreportedtobehighestfortrawlsandsetgillnets, andprobablyexceedssustainablelevelsforlocalcommonandbottlenosedolphinpopulations.Althoughinterviewdatamaybebiaseddue totheperceptionsofinterviewees,andthereforeshouldbeinterpretedwithcare,themethodologyallowedustocovermultiplesitesand fisherieswithinareasonabletimeframe.Minimizingcetacean–fisheryinteractionsrequirestheimplementationofcase-specificmanagement strategies with the active participation of fishers. For set gillnet and purse-seine fisheries, the use of acoustic deterrent devices (pingers)maypreventcetaceansfromapproaching andgettingtrappedinthenets. Fortrawl fisheries, wherebycatchappearstobeparticularlyhighatnightinwaterdepthsof100–300 m,possiblesolutionsincludetheimplementationoftime/areaclosuresandtherelocation of some fishing effort to deeper waters.