Olav Rune Godo and Arill Engas
Institute of Marine Research, P. O. Box 1870
5024 Bergen, Norway
Source - Journal of Northwest Atlantic Fishery Science, Volume 9(2): 133-139
ISSN-0250-6408
Godo, O.R. and Engas, A. 1989. Swept Area Variation with Depth and its Influence on Abundance Indices of Groundfish from Trawl Surveys. J. Northw. Atl. Fish. Sci. 9(2): 133-139. https://doi.org/10.2960/J.v9.a12
Abstract
Norwegian stratified-random bottom trawl surveys are carried out under the assumption that a constant area is swept by the trawl during a standard haul to generate abundance indices. Results from measurements of trawl geometry during a trawl survey in the Svalbard area, showed that there was a considerable depth dependency, and to a lesser extent, area/bottom stratum dependency of wingspread. Assuming that the swept area was linearly related to the wingspread, it was found that the currently applied method relatively underestimates the younger ages of cod (1-3 years) in the Svalbard area. The use of instruments for monitoring trawl geometry during all tows is one way to diminish variability in bottom trawl survey indices.
PDF
Language - English
Publisher - Northwest Atlantic Fisheries Organization (NAFO), Dartmouth, N.S., Canada
Publication Date - December 1989
Publication Type - Journal Article
Download Citation Data
Citation to clipboard
Reference management software (Endnote, Mendeley, RefWords, Zotero & most other reference management software)
LaTex, BibDesk & other specific software