Optimisation of trawl energy efficiency under fishing effort constraint

Abstract

Trawls energy efficiency is greatly affected by the drag, as well as by the swept area. The drag results in an increase of the energy consumption and the sweeping influences the catch. Methods of optimisation of the trawl design have been developed in order to reduce the volume of carburant per kg of caught fish and consequently the drag per swept area of the trawl. Based on a finite element method model for flexible netting structures, the tool modifies step by step a reference design. For each step the best-modified design, in terms of drag per swept area is kept. Such optimisation can lead to a decrease of the drag or an increase of the swept area. In the second case, that could lead to an increase of fishing effort. To avoid such increase, which could be not welcome in some fisheries; a tool of homothetic transformation of fishing gears has been developed. Such global tool (optimisation and homothetic) has shown potential saving of 39% in fuel cost without increasing the fishing effort