Who is fishing on what stock: population-of-origin of individual cod (Gadus morhua) in commercial and recreational fisheries

Abstract Atlantic cod (Gadus morhua) in Skagerrak are structured into distinct ecotypes or stock components that have been severely depleted over the past decades. To improve our understanding of how local commercial and recreational fisheries influence cod stocks, we investigated whether these user...

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Bibliographic Details
Published in:ICES Journal of Marine Science
Main Authors: Jorde, Per Erik, Kleiven, Alf Ring, Sodeland, Marte, Olsen, Esben Moland, Ferter, Keno, Jentoft, Sissel, Knutsen, Halvor
Other Authors: Grant, W Stewart, Norwegian Research Council, Sørlandet Knowledge Foundation, European Regional Development Fund
Format: Article in Journal/Newspaper
Language:English
Published: Oxford University Press (OUP) 2018
Subjects:
atlantic cod
Gadus morhua
Online Access:http://dx.doi.org/10.1093/icesjms/fsy080
http://academic.oup.com/icesjms/article-pdf/75/6/2153/31237698/fsy080.pdf
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Summary:Abstract Atlantic cod (Gadus morhua) in Skagerrak are structured into distinct ecotypes or stock components that have been severely depleted over the past decades. To improve our understanding of how local commercial and recreational fisheries influence cod stocks, we investigated whether these user groups target different stock components of cod. Cod were sampled from the recreational rod and line fishery and from commercial shrimp trawlers catching cod as by-catch. Based on a large set of single nucleotide polymorphisms (SNPs), we defined a subset of 27 semi-diagnostic SNPs designed to discriminate between two cod stock components: “inner fjord” cod and “North Sea” cod, designated by their dominant habitat preferences. Genetic assignments of fishery-caught cod indicated that 4% of individuals caught by shrimp trawlers belonged to the inner fjord cod component and 96% to the North Sea, whereas among cod caught by recreational fishers, the estimated percentages were 11.8 and 88.2%, respectively. Our findings confirm the existence of two sympatric cod stock components in coastal Skagerrak, indicating that existing management units are biologically inappropriate and should be reconsidered. Furthermore, more attention should be given to recreational angling to reduce fishing mortality on the depleted inner fjord cod component.

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