Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores

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dc.contributor.author Cruz, Maria João
dc.contributor.author Machete, Miguel
dc.contributor.author Menezes, Gui
dc.contributor.author Rogan, Emer
dc.contributor.author Silva, Mónica A.
dc.date.accessioned 2018-03-09T12:55:07Z
dc.date.available 2018-03-09T12:55:07Z
dc.date.issued 2018
dc.identifier.citation Cruz, M. J., Machete, M., Menezes, G., Rogan, E. and Silva, M. A. (2018) 'Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores', PeerJ, 6, e4285 (18pp). doi: 10.7717/peerj.4285 en
dc.identifier.volume 6
dc.identifier.startpage 1
dc.identifier.endpage 18
dc.identifier.issn 2167-8359
dc.identifier.uri http://hdl.handle.net/10468/5606
dc.identifier.doi 10.7717/peerj.4285
dc.description.abstract Small-scale artisanal fisheries can have a significant negative impact in cetacean populations. Cetacean bycatch has been documented in the pole-and-line tuna fishery in the Azores with common dolphins being the species more frequently taken. Based on data collected by observers on ∼50% of vessels operating from 1998 to 2012, we investigate the influence of various environmental and fisheries-related factors in common dolphin bycatch and calculate fleet-wide estimates of total bycatch using design-based and model-based methods. Over the 15-year study dolphin bycatch occurred in less than 0.4% of the observed fishing events. Generalized additive modelling results suggest a significant relationship between common dolphin bycatch and duration of fishing events, sea surface temperature and location. Total bycatch calculated from the traditional stratified ratio estimation approach was 196 (95% CI: 186–205), while the negative binomial GAM estimated 262 (95% CI: 249–274) dolphins. Bycatch estimates of common dolphin were similar using statistical approaches suggesting that either of these methods may be used in future bycatch assessments for this fishery. Our work shows that rates of common dolphin bycatch in the pole-and-line tuna fishery in the Azores are low, despite considerable variations between years. Dolphins caught were released alive although the fate of these individuals is unknown. Continued monitoring will provide a better understanding of dolphin bycatch and more accurate estimates essential in the development of potential mitigation measures. en
dc.description.sponsorship Fundac¸a˜o para a Cieˆncia e a Tecnologia /Fundo Regional da Cieˆncia e Tecnologia (TRACE (PTDC/MAR/74071/2006); MAPCET (M2.1.2/F/012/2011); FCT Exploratory project (IF/00943/2013/CP1199/CT0001); FEDER, the Competitiveness Factors Operational (COMPETE), QREN, POPH, the European Social Fund, the Portuguese Ministry for Science and Education, and the Proconvergencia Ac¸ores/EU Program. Funds were also provided by FCT to MARE, through the strategic project UID/MAR/04292/2013. Maria Joa˜o Cruz is supported by a DRCT doctoral grant (M3.1.2/F/008/2009-RTF/1) and Mo´nica Almeida e Silva is supported by an Cruz et al. (2018), PeerJ, DOI 10.7717/peerj.4285 14/18 FCT-Investigator contract (IF/00943/2013). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript en
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher PeerJ Inc. en
dc.relation.uri https://peerj.com/articles/4285/
dc.rights © 2018, Cruz et al. Distributed under Creative Commons CC-BY 4.0 en
dc.rights.uri https://creativecommons.org/licenses/by/4.0/
dc.subject Bycatch en
dc.subject Cetacean conservation en
dc.subject Fishery interaction en
dc.subject Statistical modelling en
dc.subject Delphinus delphis en
dc.subject Azores en
dc.title Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores en
dc.type Article (peer-reviewed) en
dc.internal.authorcontactother Emer Rogan, Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland. +353-21-490-3000 Email: e.rogan@ucc.ie en
dc.internal.availability Full text available en
dc.description.version Published Version en
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dc.description.status Peer reviewed en
dc.identifier.journaltitle PeerJ en
dc.identifier.articleid e4285


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© 2018, Cruz et al. Distributed under Creative Commons CC-BY 4.0 Except where otherwise noted, this item's license is described as © 2018, Cruz et al. Distributed under Creative Commons CC-BY 4.0
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