Is Iberian harbour porpoise (Phocoena phocoena) threatened by interactions with fisheries?

13 pages, 3 tables, 1 figure
Harbour porpoises in the Iberian Peninsula form a genetically distinct, small (around 2900 animals) and isolated population. Their main prey are commercially important fish, hence overlap between porpoise occurrence and fishing activity is almost inevitable. We compile information on bycatch mortality, mainly collected over the last 15 years, based on on-board and land-based monitoring of fishing activity, analysis of cause of death and mortality rate based on strandings, and interview surveys with fishers. All these sources provide data of questionable reliability, for example due to low and incomplete coverage of fleets by on-board observers. Nevertheless, all available estimates appear to suggest that the number of porpoises killed annually is likely to be unsustainably high. Despite some apparent incompatibility between abundance data, estimated bycatch mortality rates and genetic data, we suggest that both new mitigation action to reduce bycatch and improved monitoring are needed to secure the future of this population
The authors thank the funding bodies who have supported monitoring of cetacean strandings in Galicia and associated research over the last 30 years, including the Xunta de Galicia (Dirección Xeral de Patrimonio Natural, Consellería do Mar, and Consellería de Medio Ambiente Territorio y Vivienda), Fundación Biodiversidad, ASCOBANS (SSFA/ASCOBANS/2010/4), the European Commission (LIFE+ Indemares project, several Marie Skłodowska-Curie projects, FP5 project BIOCET (EVK3-CT-2000-00027), DG Fisheries Data Collection Project 97/089) and Fundação para a Ciência e a Tecnologia (FCT).