Mesh Size and the New England Groundfishery- Applications and Implications

摘要

Mesh size control has been advocated from the earliest days of the otter trawl fishery in the United States. Researchers determined that larger meshes in the cod end of a trawl reduce discarding by allowing small fish to escape; a process known as size-seletion. This selectivity is measured by the selection factor-the relationship between the 50% retention length and the stretched length of the mesh. Selection factors vary by species, net material, duration of tow, speed of tow, size of catch, and with variations in mesh size. Cod end mesh size experiments were conducted aboard eight New England otter trawlers during the period December 1977 to October 1978 to examine the possible effects of increasing the mesh size in that fishery. Mesh size regulation as a management tool first requires the determination of the objectives in order to choose the size mesh. Enforcement difficulty, especially in the New England mixed fishery, is the greatest obstacle to overcome.