Methods of Determining the Mesh Selectivity Curve of Trawlnet

Abstract

This paper includes a theory and methods of determining mesh selectivity curve for a specified mesh size of codend in trawlnet from a fishing experiment with several mesh sizes. On a few assumptions, the mesh selectivity of mesh size m for fish of length l was theoretically approximated by a function of (1-101(m—m0) in certain ranges of l and m. Here, l0and moare constants. On the basis of the above statement, the authors derived the respective methods for determining the mesh selectivity curve from covered-net and comparative fishing experiments. In addition, this paper applied the derived methods to Margetts' data as a numerical example and discussed some problems on the methods. © 1989, The Japanese Society of Fisheries Science. All rights reserved.