Improvement of Selectivity of Trawl Codends

Summary

This report describes trials by Seafish Technology into the selective characteristics of codends of three different mesh sizes; these were, nominally, 100, 110 and 120mm. The work was undertaken for MAFF’s Chief Scientist’s Group under their project reference MF0601. The fishing trials were conducted on a chartered vessel MFV Heather Sprig, mainly in the Moray Firth, and targeting haddock, whiting and cod. The experiments used the covered codend technique and also measured essential gear performance parameters by use of a Scanmar package. Selection curves were calculated from the ratio of total fish caught against those only in the codend. Problems were encountered in two respects. First the numbers of cod caught were very low and little significance can be attributed to that data set. Secondly, very large numbers of small haddock and whiting were encountered and there is a need for some caution in interpreting the date because of this. The data have only been treated to a limited amount of analysis because the customer is expected to incorporate them into a general codend selectivity model This report has been produced from a scanned original and may therefore contain some formatting and other inaccuracies. In cases where this affects the technical content, a paper copy of the original report can still be obtained from Seafish.

Author

• K. Arkley

Publication Reference No.

SR421

Publication date

01 May 1992