Results of fishing experiments with square mesh in the cod end of demersal trawls

Abstract

Fishing experiments are conducted with alternate haul technique and trouser codend method using square mesh codend in contrast to conventional diamond mesh codend in demersal trawls with 30 mm and 20 mm mesh size to assess the comparative retention and experiment of juveniles of both fin fish and shell fish to suggest conservation measures for the trawl industry for better management. Results indicate that more number of smaller size groups of fin fish and shell fish escaped from square mesh codend than that of diamond mesh codend. It is more evident in the case of small mesh size codend with 20 mm mesh and operated in shallow waters. In the case of 30 mm mesh codend, selection was not so significant between square mesh and diamond mesh as the size of mesh is sufficient enough to provide experiment for juveniles. The size of mesh is mote critical rather than the shape of mesh with increasing mesh size in larger meshes. Moreover, juveniles are less represented in offshore and deeper waters. Fabrication, rigging and construction of square mesh codend, trouser codends and fitting of covers for collection of escaped fishes are briefly mentioned.