A new design of a flexible separator panel (eyo grid) to reduce by-catch in coastal shrimp beam trawl fishery in Nigeria

Abstract

A new design of a flexible separator grid consisting of a partition and excluder panels is developed and inserted into trawl codend to reduce by-catch species in coastal beam trawl fisheries for white shrimps, Nematopalaemon hastatus. Simultaneous paired comparisons against control codend showed that the experimental codend significantly reduced the by-catch of juvenile fishes up to 82.36% (t-test, P<0.05; 0.01) with a corresponding loss of 26.98% of target shrimps Nematopalaemon hastatus. Fish specimens of 11-30cm total length were highly excluded from the experimental codend. Abundance of commercially important bycatch species weight were significantly reduced in experimental codend e.g. Pseudotolithus typus (96.68%, p<0.05; 0.01), Cynoglossus senegalensis (85.5%, p<0.05; 0.01) and Pentanemus quinquarius (81.98%, p<0.05; 0.01). At family level, reduction in the number of 9 out of 13 important by-catch families analysed were significant e.g. Sciaenidae, Trichiuridae, Clupeidae, Drepanidae and Carangidae (p<0.05; 0.01). Flattened fish families were not in number signicantly reduced in experimental codend e.g. Carcharhinidae and Dasyatidae (p<0.05; 0.01). The design concept, by-catch and shrimps reduction characteristics of the flexible netting separator grid are discussed.

Key words: New design, netting grid, By-catch, Shrimp, Trawl Fishery, Nigeria