Fish Population Dynamic and Stock Assessment

10.4.9. Bycatch reduction technologies

‘Target catch’ is the species or species assemblage primarily sought in a fishery, ‘incidental catch’ is the retained catch of non-targeted species and ‘discarded catch’ is that portion of catch returned to the sea because of economic, legal or personal considerations (Alverson et al., 1994). Bycatch includes both discarded and incidental catch. In addition to the non-targeted finfishes and invertebrates, bycatch also involve threatened and protected species like sea turtles.

Different types of bycatch reduction technologies have been developed in the fishing industry around the world (Prado, 1993; Eayrs, 2005; Boopendranath et al.,2006; Gibinkumar et al., 2005; Sabu et al.,2005; Boopendranath et al., 2007 a; Kennelly, 2007; Boopendranath et al., 2008;2009;Boopendranath and Pravin, 2009). Devices developed to exclude the endangered species like turtle and to reduce the non-targeted species in shrimp trawling are collectively known an Bycatch Reduction Devices (BRDs). These devices have been developed taking into consideration variation in the size and differential behaviour pattern of shrimp and other animals inside the net. BRDs can be broadly classified into three categories based on the type of materials used for their construction, viz., Soft BRDs, Hard BRDs, and Combination BRDs. Soft BRDs make use of soft materials like netting and rope frames for separating and excluding bycatch. Hard BRDs are those, which use hard or semi-flexible grids and structures for separating and excluding bycatch. Combination BRDs use more than one BRD, usually hard BRD in combination with soft BRD, integrated to a single system. Juvenile Fish Excluder cum Shrimp Sorting Device (JFE-SSD) is a Smart Gear award winning design (WWF) developed by CIFT for protecting juveniles and for pre-sorting of the catch (Boopendranath et al., 2008; WWF, 2009).