Title

Catchability of Pelagic Trawls for Sampling Deep-Living Nekton in the Mid-North Atlantic

Document Type

Article

Publication Date

1-2011

Publication Title

ICES Journal of Marine Science

Keywords

Catchability, Gear comparison, Mid-Atlantic Ridge, Nekton, Pelagic ecosystems, Sampling

ISSN

1054-3139

Volume

68

Issue/No.

2

First Page

377

Last Page

389

Abstract

Material collected in summer 2004 from the Mid-Atlantic Ridge between Iceland and the Azores with three pelagic trawls was used to estimate relative catchabilities of common fish, cephalopod, decapod, and jellyfish species. Catchability is defined as the ratio of numbers caught between two trawls, standardized for towed distance. Taxon-specific catchability coefficients were estimated for two large pelagic trawls with graded meshes, using a smaller pelagic trawl with a uniform mesh size as the reference trawl. Two of the trawls were equipped with multiple opening–closing codends that allowed sampling of different depth layers. Generalized linear and mixed models suggest that most of the taxa have catchabilities much lower than expected from the area of opening alone, indicating that only a few species are herded by the large mesh at the mouth of larger trawls. Catchability coefficients across taxa show a very large spread, indicating that the sampled volume for the larger trawls with graded meshes was highly taxon-specific. Part of this variability can be explained by body size and taxonomic group, the latter probably reflecting differences in body form and behaviour. The catchability estimates presented here form the basis for combining data for quantitative analyses of community structure.

Comments

©2010 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.

Additional Comments

European Community's Sixth Framework Programme contract #: GOCE-CT-2003-505446

ORCID ID

0000-0002-5280-7071

DOI

10.1093/icesjms/fsq089

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