Characteristics of fishing operations, environment and life history contributing to small cetacean bycatch in the northeast Atlantic

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dc.contributor.authorBrown, Susie
dc.contributor.authorReid, David
dc.contributor.authorRogan, Emer
dc.contributor.funderDepartment of Communications, Energy and Natural Resources, Ireland
dc.contributor.funderDepartment of Agriculture, Fisheries and Food, Ireland
dc.contributor.funderIrish Government
dc.contributor.funderEuropean Commission
dc.date.accessioned2016-02-17T11:43:39Z
dc.date.available2016-02-17T11:43:39Z
dc.date.issued2014
dc.description.abstractFisheries bycatch is a key threat to cetacean species globally. Managing the impact requires an understanding of the conditions under which animals are caught and the sections of the population affected. We used observer data collected on an albacore tuna gillnet fishery in the northeast Atlantic, to assess operational and environmental factors contributing to bycatch of common and striped dolphins, using generalised linear models and model averaging. Life history demographics of the captured animals were also investigated. In both species, young males dominated the catch. The age ratio of common dolphins was significantly different from that estimated for the population in the region, based on life tables (G = 17.1, d.f. = 2, p = 0.002). Skewed age and sex ratios may reflect varying vulnerability to capture, through differences in behaviour or segregation in populations. Adult females constituted the second largest portion of the bycatch for both species, with potential consequences for population sustainability. Depth was the most important parameter influencing bycatch of both species and reflected what is known about common and striped dolphin habitat use in the region as the probability of catching common dolphins decreased, and striped dolphins increased, with increasing depth. Striped dolphin capture was similarly influenced by the extent to which operations were conducted in daylight, with the probability of capture increasing with increased operations in the pre-sunset and post-sunrise period, potentially driven by increased ability of observers to record animals during daylight operations, or by diurnal movements increasing contact with the fishery. Effort, based on net length and soak time, had little influence on the probability of capturing either species. Our results illustrate the importance of assessing the demographic of the animals captured during observer programmes and, perhaps more importantly, suggest that effort restrictions alone may not be sufficient to eradicate bycatch in areas where driftnets and small cetaceans co-occur.en
dc.description.sponsorshipIrish Government (Beaufort Ecosystem Approach to Fisheries Management Award); Department of Communications, Energy and Natural Resources, Ireland and Department of Agriculture, Fisheries and Food, Ireland (Beaufort Marine Research Award); European Commission (FAIR-CT95-0523)en
dc.description.statusPeer revieweden
dc.description.versionPublished Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.articleide104468
dc.identifier.citationBrown S, Reid D, Rogan E (2014) Characteristics of Fishing Operations, Environment and Life History Contributing to Small Cetacean Bycatch in the Northeast Atlantic. PLoS ONE 9(8): e104468. doi:10.1371/journal.pone.0104468
dc.identifier.doi10.1371/journal.pone.0104468
dc.identifier.issn1932-6203
dc.identifier.issued8en
dc.identifier.journaltitlePLOS ONEen
dc.identifier.urihttps://hdl.handle.net/10468/2327
dc.identifier.volume9en
dc.language.isoenen
dc.publisherPublic Library of Scienceen
dc.rights© 2015 Brown et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are crediteden
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectDolphins Delphinus delphisen
dc.subjectPorpoise Phocoena phocoenaen
dc.subjectCommon dolphinen
dc.subjectMarine mammalsen
dc.subjectBy-catchen
dc.subjectIncidental catchesen
dc.subjectGillnet fisheriesen
dc.subjectTrawl fisheryen
dc.subjectSea turtlesen
dc.subjectOceanen
dc.titleCharacteristics of fishing operations, environment and life history contributing to small cetacean bycatch in the northeast Atlanticen
dc.typeArticle (peer-reviewed)en
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