Shrimp fishery by mini-trawling along Alleppey coast, Kerala

Abstract

Penaeid shrimps from nearshore waters in 5-12 m depth range are regularly exploited by plank built boats locally known as murivallan which operate mini - trawl (cod end mesh size 15-20 mm) along Alleppey coast in Kerala. Observations made for three seasons at Valanjavazhy (1994-97) and at Pallithode (2002-05) indicated that 935 t (cpue 42 kg) and 145 t (37kg) of shrimps were landed by mini-trawl at these centres respectively. The fishing season extended from September to MayIJune depending on the onset of monsoon. Parapenaeopsis stylifera and Metapenarus dobsoni were the main contributors to the shrimp fishery. While the former predominated (91%) the fishery at Valanjavazhi, both the species showed almost equal representation at Pallithode. Species-wise details on size distribution, sex ratio, maturity and spawning season have been indicated. In spite of discarding smaller P. stylifera (< 41 mm in total length), the commercial catch at Valanjavazhy consisted more than 50% juveniles during many months in the observation period. I stylifera completes its nursery phase in the nearshore areas along the coast and fishing them at this stage is detrimental to the fishery of this species. The impact of mini-trawl operation on the shrimp resources off Kerala along with possible management measures is discussed.