Marine Institute Open Access Repository >
Marine Institute Community of Research Publications >
Scientific Papers >
Peer Reviewed Scientific Papers >

Please use this identifier to cite or link to this item:

Title: Significant differences in the length–weight relationships of neighbouring stocks can result in biased biomass estimates: examples of haddock (Melanogrammus aeglefinus, L.) and whiting (Merlangius merlangus, L.)
Authors: McGrath, D
Gerritsen, H.D.
Keywords: length-weight
biomass estimate
Issue Date: 2007
Publisher: Elsevier
Citation: Gerritsen, H.D. & McGrath, D., "Significant differences in the length-weight relationships of neighbouring stocks can result in biased biomass estimates: Examples of haddock (Melanogrammus aeglefinus, L.) and whiting (Merlangius merlangus, L.)", Fisheries Research, Volume 85, Issues 1-2, June 2007, Pages 106-111
Series/Report no.: Fisheries Research;85 (1-2)
Abstract: Length–weight relationships of fish are often used to estimate the biomass of length distributions or to obtain indices of condition. Although large-scale spatial trends are known to exist, it is often assumed that length–weight relationships do not vary significantly within stocks or between neighbouring stocks. The present study examined length–weight relationships of 1334 haddock (Melanogrammus aeglefinus) and 1186 whiting (Merlangius merlangus) collected on a groundfish survey in the waters around Ireland in 2004. Additionally, condition indices were estimated for individual fish and for length frequency samples. The length–weight regression showed a significant area effect and no differences between the sexes. The condition indices showed a moderate spatial structure for both species: around 25% of the variability could be explained by the location of the samples, the rest of the variability was due to other sources. Length–weight relationships did not appear to vary significantly within stocks, however differences between stocks were significant. In the present case, a bias of up to 10% could occur in biomass estimates as a result of applying length–weight relationships of one stock to length data of a neighbouring stock.
Description: NOTICE: this is the author’s version of a work that was accepted for publication in Fisheries Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fisheries Research, [Volume 85, Issues 1-2, (June 2007)] doi:10.1016/j.fishres.2007.01.004
ISSN: 0165-7836
Appears in Collections:Peer Reviewed Scientific Papers

Files in This Item:

File Description SizeFormat
Gerritsen- Significant differences.pdf775.28 kBAdobe PDFView/Open
Use License

Items in the Marine Institute Open Access Repository are protected by copyright, with all rights reserved, unless otherwise indicated.


Valid XHTML 1.0! Marine Institute Copyright © 2011  - Feedback