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Pingers reduce cetaceans mortality bycatch in Portuguese trammel nets

Andreia T. Pereira1, 2*, Catarina Eira1, 2, Marisa Ferreira2, 3, Silvia Monteiro1, 2, Jorge Bastos-Santos1, 2, Helder Araújo1, 2, Isabel B. Oliveira1, 2 and Jose Vingada1, 2
  • 1 Centre for Environmental and Marine Studies CESAM, University of Aveiro, Portugal
  • 2 Sociedade Portuguesa de Vida Selvagem, Portugal
  • 3 Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Portugal

Currently, cetacean bycatch is a major problem for both fisheries and species conservation. In Portugal, bycatch represents one of the most important mortality sources for small cetaceans. Strandings data reveal that 44-54% of the common-dolphin mortality is associated with fisheries interactions along the Portuguese coast. To reduce cetacean-fishery interactions in EU waters, the use of pingers became obligatory under the Council regulation (EC) 812/2004 in specific fishing areas. Particularly in the case of Harbour porpoises, data on their ecology and anthropogenic impacts are needed to build effective management plans, including conservation and mitigation measures. In fact, the recently proposed Harbour porpoise ecotype Phocoena phocoena meridionalis, presents a “Vulnerable” status in Portugal, declining abundances and coastal preferences overlapping human activities. During 8 years (2009-2016), essays were in place using pingers in trammel nets in mainland Portuguese waters. Essays were monitored through voluntary declaration logbooks. To compare catch per effort values, the Mann-Whitney test was used in GraphPad Prism 5.01c. Heatmaps were generated to identify interaction and mortality locations and the minimum convex polygons (MCP) were estimated to compare areas with mortality in control sets versus experimental sets (Quantum Gis V.2.18). Incidental captures of common dolphin, bottlenose dolphin, and harbour porpoise were registered. Results showed that cetacean interactions with trammel nets in Portugal involve mostly common dolphins followed by Harbour porpoises. Approximately 82% of cetacean bycatch resulted in mortality. FUMUNDA pingers led to a decrease in cetacean bycatch mortality (less 57,7% in fishing events using nets with pingers in comparison to nets without pingers) with no significant effect on CPUE. However, it is important to note that a mitigation measure that is effective for one species or for one fishery may not work for other species and / or other fisheries. Thus, conservation and management measures should be systematically re-evaluated and adapted to different factors.

Keywords: Small cetaceans, conservation, cetacean bycatch, Trammel nets, Pingers

Conference: IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.

Presentation Type: Poster Presentation

Topic: Biodiversity, Conservation and Coastal Management

Citation: Pereira AT, Eira C, Ferreira M, Monteiro S, Bastos-Santos J, Araújo H, Oliveira IB and Vingada J (2019). Pingers reduce cetaceans mortality bycatch in Portuguese trammel nets. Front. Mar. Sci. Conference Abstract: IMMR'18 | International Meeting on Marine Research 2018. doi: 10.3389/conf.FMARS.2018.06.00027

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Received: 04 May 2018; Published Online: 07 Jan 2019.

* Correspondence: Miss. Andreia T Pereira, Centre for Environmental and Marine Studies CESAM, University of Aveiro, Aveiro, Portugal, aftpereira@gmail.com