Catchability of pelagic trawls for sampling deep-living nekton in the mid-North Atlantic.

Heino, M., Porteiro, F. M., Sutton, T. T., Falkenhaug, T., Godo, O. R. and Piatkowski, Uwe (2011) Catchability of pelagic trawls for sampling deep-living nekton in the mid-North Atlantic. Open Access ICES Journal of Marine Science, 68 (2). pp. 377-389. DOI 10.1093/icesjms/fsq089.

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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.

Document Type: Article
Keywords: Ecology; Ichthyology; catchability, gear comparison, Mid-Atlantic Ridge, nekton, pelagic ecosystems, sampling
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EV Marine Evolutionary Ecology
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1093/icesjms/fsq089
ISSN: 1054-3139
Date Deposited: 04 Jan 2011 10:12
Last Modified: 23 Sep 2019 19:12

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