Iberian Atlantic waters are heavily exploited by Spanish and Portuguese fisheries. Overlaps between fishery target species and cetacean diet, and between fishing grounds and cetacean foraging areas, can lead to cetacean-fishery interactions including bycatch mortality of cetaceans.
The present study assesses cetacean distribution, habitat preferences and hotspots for cetacean-fishery interactions by using a cooperative research approach with stakeholder participation (fishers, fisheries observers, fisheries authorities, scientists), as well as the combination of different opportunistic data sources (interviews, on-board observations). The usefulness of each data type is evaluated. The implications of results for the monitoring and mitigation of cetacean-fishery interactions are discussed.
Generalized linear models and GIS maps were used to relate cetacean occurrence patterns to environmental variables (geographic area, water depth, coastal morphology) and to fishing activities (fishing grounds, fisheries target species). Common and bottlenose dolphins were the most frequently sighted species, the former in waters >50 m, frequently from purse seiners and trawlers, and the latter particularly inside the south Galician rias and close to vessels operating further offshore in Portuguese waters. Harbour porpoises were seen over the whole continental shelf, often next to beach seines, while long-finned pilot whales and striped dolphins were mostly seen from vessels fishing offshore.
Results suggest that cetacean occurrence is linked to prey distribution and that interactions with fisheries are most likely for common dolphins (with coastal purse seines and offshore trawls), bottlenose dolphins and harbour porpoises (coastal nets). The different data sources were complementary and provided results broadly consistent with previous studies on cetacean occurrence in the same area, although sightings frequency for some cetacean species was biased by survey method. Opportunistic sampling has certain restrictions concerning reliability, but can cover a wide area at comparatively low cost and make use of local ecological knowledge to yield information required for cetacean conservation.
|Number of pages||17|
|Journal||Aquatic Conservation: Marine and Freshwater Ecosystems|
|Early online date||26 Jun 2014|
|Publication status||Published - 12 Feb 2015|
We wish to express our gratitude to all Galician and Portuguese fishers that took part in the survey for sharing their time and information with us. We would also like to acknowledge the support of the Galician Council for Rural and Marine Affairs (Consellería do Medio Rural e do Mar, Xunta de Galicia), namely the cooperation of the fisheries´ observers (Luis Pérez Miser, Francisco José López,
Juan Chapela Portela, Felix Barreiro, Candido Aguiar Couto, José María García Rozamontes, José Manuel Garrido Vispo, José Manuel Pérez Veres, Javier García Romero, Juan González Pérez), the coordinators (Ricardo Arnaiz Ibarrondo, Francisco Filgueira Rodríguez) and the staff (Manuel García Tasende, Jorge Ribó Landín, José Manuel Campelos Álvarez) of the Technical Unit for Inshore Fisheries. Furthermore, we would like to thank Baltasar Patiño and Gersom Costas for provision of background information and logistical support, and Juan Santos and Edward Morgan, for assisting with the interviewing. Interviews in Galicia were carried out in the framework of the project ECOSUMMER (ECOsystem approach to Sustainable Managament of the Marine Environment and its living Resource) with EU funding (projects MEXC-CT-2006-042337 and MEST-CT-2005-020501). The interview survey in Portugal was conducted under the SafeSea Project (Sustainable local fisheries and promotion of a safe sea for cetaceans) and supported by the EEA Grants programme (EEA Financial Mechanism 2004-2009). SG was also funded by the German Academic
Exchange Service (DAAD) and the Fundação para a Ciência e a Tecnologia (FCT). MBS participation was part of the EU FP7 grant MYFISH (no. 289257) and the LOTOFPEL project (Plan Nacional de I + D + I, CTM 2010-16053). The Whalewatch Project was financed by the Xunta de Galicia (programme PEME I+D e I+D SUMA).
- habitat mapping
- North-West Spain
- Galicia NW Spain
- harbor porpoise
- marine mammals
- interview survey
- adjacent waters