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Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)

Antarctic krill (Euphausia superba) is an abundant fishery resource, the harvest levels of which are expected to increase. However, many of the length classes of krill can escape through commonly used commercial trawl mesh sizes. A vital component of the overall management of a fishery is to estimat...

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Autores principales: Krafft, Bjørn A., Krag, Ludvig A., Engås, Arill, Nordrum, Sigve, Bruheim, Inge, Herrmann, Bent
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5021277/
https://www.ncbi.nlm.nih.gov/pubmed/27622510
http://dx.doi.org/10.1371/journal.pone.0162311
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author Krafft, Bjørn A.
Krag, Ludvig A.
Engås, Arill
Nordrum, Sigve
Bruheim, Inge
Herrmann, Bent
author_facet Krafft, Bjørn A.
Krag, Ludvig A.
Engås, Arill
Nordrum, Sigve
Bruheim, Inge
Herrmann, Bent
author_sort Krafft, Bjørn A.
collection PubMed
description Antarctic krill (Euphausia superba) is an abundant fishery resource, the harvest levels of which are expected to increase. However, many of the length classes of krill can escape through commonly used commercial trawl mesh sizes. A vital component of the overall management of a fishery is to estimate the total fishing mortality and quantify the mortality rate of individuals that escape from fishing gear. The methods for determining fishing mortality in krill are still poorly developed. We used a covered codend sampling technique followed by onboard observations made in holding tanks to monitor mortality rates of escaped krill. Haul duration, hydrological conditions, maximum fishing depth and catch composition all had no significant effect on mortality of krill escaping 16 mm mesh size nets, nor was any further mortality associated with the holding tank conditions. A non- parametric Kaplan-Meier analysis was used to model the relationship between mortality rates of escapees and time. There was a weak tendency, though not significant, for smaller individuals to suffer higher mortality than larger individuals. The mortality of krill escaping the trawl nets in our study was 4.4 ± 4.4%, suggesting that krill are fairly tolerant of the capture-and-escape process in trawls.
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spelling pubmed-50212772016-09-27 Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba) Krafft, Bjørn A. Krag, Ludvig A. Engås, Arill Nordrum, Sigve Bruheim, Inge Herrmann, Bent PLoS One Research Article Antarctic krill (Euphausia superba) is an abundant fishery resource, the harvest levels of which are expected to increase. However, many of the length classes of krill can escape through commonly used commercial trawl mesh sizes. A vital component of the overall management of a fishery is to estimate the total fishing mortality and quantify the mortality rate of individuals that escape from fishing gear. The methods for determining fishing mortality in krill are still poorly developed. We used a covered codend sampling technique followed by onboard observations made in holding tanks to monitor mortality rates of escaped krill. Haul duration, hydrological conditions, maximum fishing depth and catch composition all had no significant effect on mortality of krill escaping 16 mm mesh size nets, nor was any further mortality associated with the holding tank conditions. A non- parametric Kaplan-Meier analysis was used to model the relationship between mortality rates of escapees and time. There was a weak tendency, though not significant, for smaller individuals to suffer higher mortality than larger individuals. The mortality of krill escaping the trawl nets in our study was 4.4 ± 4.4%, suggesting that krill are fairly tolerant of the capture-and-escape process in trawls. Public Library of Science 2016-09-13 /pmc/articles/PMC5021277/ /pubmed/27622510 http://dx.doi.org/10.1371/journal.pone.0162311 Text en © 2016 Krafft 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, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Krafft, Bjørn A.
Krag, Ludvig A.
Engås, Arill
Nordrum, Sigve
Bruheim, Inge
Herrmann, Bent
Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)
title Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)
title_full Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)
title_fullStr Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)
title_full_unstemmed Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)
title_short Quantifying the Escape Mortality of Trawl Caught Antarctic Krill (Euphausia superba)
title_sort quantifying the escape mortality of trawl caught antarctic krill (euphausia superba)
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5021277/
https://www.ncbi.nlm.nih.gov/pubmed/27622510
http://dx.doi.org/10.1371/journal.pone.0162311
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