Yellowfin tuna fishery by traditional fishermen at Visakhapatnam, Andhra Pradesh

Abstract

Yellowfin tuna Thunnus albacares in the oceanic waters beyond the depths of 200 m off Visakhapatnam is exploited in recent years by the local fisherfolk. Hooks & line and trolls operated mostly from nonmechanized traditional craft (catamaran) are the main methods of exploitation. The average annual landing of yellowfin tuna by these crafts at Visakhapatnam was 1,515 t during 2004-2006. December followed by May recorded peak catches. A wide size group represented the fishery with the fork length measuring from 30 cm to 175 cm with a major mode at 135 cm. Fishes above 80 cm were found to be mature and the size at first maturity was estimated to be between 85 and 90 cm. Males were dominant with a male: female ratio of 1: 0.53. The length-weight relationship was W= 0.017077L 2.976. Food consisted of fishes (pelagic teleosts), crustaceans (crabs and shrimps) and molluscs (squids). The good returns from the fishery has encouraged the mechanized sector to venture into oceanic tuna fishing. The fishery is still in its infancy and more research has to be carried out to suggest proper management measures.