Iberian harbour porpoise - an update on fishery bycatch mortality

• Main Authors: Pierce, Graham J., Petitguyot, Marie, Gutiérrez-Muñoz, Paula, Fernández Fernández, Diego, Fariñas, Andrea, Read, Fiona L., Saavedra, Camilo, López, Alfredo, Martínez-Cedeira, José A.
• Format: Other/Unknown Material
• Language: English
• Published: 2022
• Subjects: Harbour porpoise
• Online Access: http://hdl.handle.net/10261/276506

15 pages, 5 tables Several recent studies have suggested that the Iberian harbour porpoise is genetically and morphologically distinct and may represent a separate subspecies. The main threat facing this population is fishery bycatch. Recent data on porpoise bycatch are available from strandings and on-board observations. Generally, more bycaught porpoises are recorded from strandings than from on-board observations. Portugal has previously reported porpoise bycatches based on on-board observation in Iberian waters, although Spain has consistently reported zero porpoise bycatch Data from on-board observations of porpoise bycatch in Iberian waters (2005-2021) submitted to ICES WKMOMA appear to be anomalous in that they apparently do not include the majority of bycatch records previously submitted to ICES WGBYC. The minimum annual estimate of bycatch mortality, consisting of documented bycatch mortalities from strandings and observers in both Spain and Portugal, is around 0.5% (14 animals per year). Both types of data can be used to estimate both total bycatch and bycatch rate, given a population size estimate and (in the case of strandings) an overall mortality rate derived from a life table. In both cases, it is necessary to assume that samples are representative in order to scale up to the population level, and in both cases this is rather unlikely. Nevertheless, the results from all data sources are remarkably consistent, suggesting an annual bycatch mortality rate of no less than 8% (around 230 individuals) per year Peer reviewed