Swept area variation with depth and its influence on stratified trawl surveys indices on Arcto-Norwegian cod
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Stratified trawl surveys have been carried out in the Barents Sea and the Svalbard areas since 1981. Based on the assumption of a constant area swept by the trawl during a standard trawl haul at any depth, swept area abundance indices have been presented for both areas. The results have been used in the management of the Arcto-Norwegian cod stock. In this paper results from measurements of trawl geometry during trawling operation during a standard stratified trawl survey in the Svalbard area in September-October 1985 are presented and the implication on the trawl indices of these results are discussed.