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

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 o...

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Autores principales: Cruz, Maria João, Machete, Miguel, Menezes, Gui, Rogan, Emer, Silva, Mónica A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: PeerJ Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813588/
https://www.ncbi.nlm.nih.gov/pubmed/29456883
http://dx.doi.org/10.7717/peerj.4285
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author Cruz, Maria João
Machete, Miguel
Menezes, Gui
Rogan, Emer
Silva, Mónica A.
author_facet Cruz, Maria João
Machete, Miguel
Menezes, Gui
Rogan, Emer
Silva, Mónica A.
author_sort Cruz, Maria João
collection PubMed
description 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.
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spelling pubmed-58135882018-02-16 Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores Cruz, Maria João Machete, Miguel Menezes, Gui Rogan, Emer Silva, Mónica A. PeerJ Aquaculture 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. PeerJ Inc. 2018-02-12 /pmc/articles/PMC5813588/ /pubmed/29456883 http://dx.doi.org/10.7717/peerj.4285 Text en © 2018 Cruz et al. http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited.
spellingShingle Aquaculture
Cruz, Maria João
Machete, Miguel
Menezes, Gui
Rogan, Emer
Silva, Mónica A.
Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores
title Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores
title_full Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores
title_fullStr Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores
title_full_unstemmed Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores
title_short Estimating common dolphin bycatch in the pole-and-line tuna fishery in the Azores
title_sort estimating common dolphin bycatch in the pole-and-line tuna fishery in the azores
topic Aquaculture
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813588/
https://www.ncbi.nlm.nih.gov/pubmed/29456883
http://dx.doi.org/10.7717/peerj.4285
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