Journal Article

Time changes in fishing power in the Danish cod fisheries of the Baltic Sea

Paul Marchal, J. Rasmus Nielsen, Holger Hovgård and Hans Lassen

in ICES Journal of Marine Science

Published on behalf of ICES/CIEM

Volume 58, issue 1, pages 298-310
Published in print January 2001 | ISSN: 1054-3139
Published online January 2001 | e-ISSN: 1095-9289 | DOI: http://dx.doi.org/10.1006/jmsc.2000.1011
Time changes in fishing power in the Danish cod fisheries of the Baltic Sea

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Using nominal fishing effort to control fishing mortality and using cpue data from commercial fisheries as abundance indices require ability to correct fishing power for temporal development. It is often assumed in ICES stock assessments that fishing power is constant over time. However, experience has suggested that this assumption may be false. This study investigates the time dynamics of an Index of Fishing Power (IFP). This index is based on the fleet's cpue, relative to the cpue of a subset of vessels from the same fleet. The primary characteristic of the reference vessels is that their fishing power has not varied much over time. IFP is calculated for some of the Danish cod fisheries in the Baltic Sea. IFP appeared to be independent of the vessel composition of the reference sub-fleet and for the fleets fishing in the Eastern Baltic Sea, but less so for the Western Baltic Sea fleets. Variations in IFP are analysed by a GLM (General Linear Model). Results suggest that fishing power has developed in the Eastern Baltic Sea cod fishery at an annual rate of 2% and 6% for trawlers and gillnetters respectively. Mechanisms of fishing power creeping may include increased technical efficiency and also changes in vessel composition of the fleets over the period of analysis.

Keywords: variations in fishing power; catchability; effort regulation; fishing effort; fishing mortality; cpue; GLM; Danish commercial fisheries; Baltic Sea cod

Journal Article.  0 words. 

Subjects: Environmental Science ; Marine and Estuarine Biology

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