A novel tool to mitigate by-catch mortality of baltic seals in coastal fyke net fishery

Developing methods to reduce the incidental catch of non-target species is important, as by-catch mortality poses threats especially to large aquatic predators. We examined the effectiveness of a novel device, a "seal sock", in mitigating the by-catch mortality of seals in coastal fyke net...

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Published inPloS one Vol. 10; no. 5; p. e0127510
Main Authors Oksanen, Sari M, Ahola, Markus P, Oikarinen, Jyrki, Kunnasranta, Mervi
Format Journal Article
LanguageEnglish
Published United States Public Library of Science 18.05.2015
Public Library of Science (PLoS)
Subjects
Analysis
Animals
Baltic States
Biology
By-catch
Bycatch
Coastal environments
Commercial fishing
Conservation of Natural Resources - methods
Female
Fish
Fisheries
Fisheries management
Fishing
Fishing equipment
Fishing gear
Fishing nets
Fyke nets
Grey seals
Halichoerus grypus
Health aspects
Male
Males
Marine mammals
Mortality
Nets
Oceans and Seas
Phoca
Population
Predators
Salmo trutta
Seals
Seals, Earless
United States
Baltic States
United States
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Summary:Developing methods to reduce the incidental catch of non-target species is important, as by-catch mortality poses threats especially to large aquatic predators. We examined the effectiveness of a novel device, a "seal sock", in mitigating the by-catch mortality of seals in coastal fyke net fisheries in the Baltic Sea. The seal sock developed and tested in this study was a cylindrical net attached to the fyke net, allowing the seals access to the surface to breathe while trapped inside fishing gear. The number of dead and live seals caught in fyke nets without a seal sock (years 2008-2010) and with a sock (years 2011-2013) was recorded. The seals caught in fyke nets were mainly juveniles. Of ringed seals (Phoca hispida botnica) both sexes were equally represented, while of grey seals (Halichoerus grypus) the ratio was biased (71%) towards males. All the by-caught seals were dead in the fyke nets without a seal sock, whereas 70% of ringed seals and 11% of grey seals survived when the seal sock was used. The seal sock proved to be effective in reducing the by-catch mortality of ringed seals, but did not perform as well with grey seals.
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Conceived and designed the experiments: SMO MPA JO MK. Performed the experiments: SMO MPA JO MK. Analyzed the data: SMO. Contributed reagents/materials/analysis tools: SMO MPA JO MK. Wrote the paper: SMO MPA JO MK.
Competing Interests: The authors have declared that no competing interests exist.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0127510