Development of a bycatch reduction device (BRD) for shrimp beam trawl using flexible materials

Abstract

This study aimed to design a bycatch reduction device (BRD) for shrimp beam trawl, which is manufactured by flexible materials to reduce bycatch for the gear in the South Sea of Korea. The model test was carried out to understand the shape of the gear in the water and to measure the variation of flow speed due to the BRD in a circulating water channel. Catches were compared between a shrimp beam trawl without BRD (control gear) and others with BRD (treatment gears) in the field. BRDs were two different types in this study. In the case of BRD (a), a square-shaped grid net and a funnel-shaped net were installed in the front part of the cod end to help fish sorting and expelling through the outlet at the bottom. BRD (b) has one more outlet which is added at the upper part of the BRD (a). On the model test, water speed was reduced a little in the gear by installing the BRD. At the results of comparing with a control gear, the bycatch (%) of fish excluding shrimp was reduced between 17 and 68% using BRD (a) and 5 and 66% for BRD (b) respectively. By the signed test of significant level 0.05, the quantity of shrimp catches for BRD (a) was not different in comparison to the control gear but it decreased for the gear installing BRD (b).