Observations on fishery and biology of yellowfin tuna Thunnus albacares (Bonnaterre, 1788) from Lakshadweep waters

Abstract

The yellowfin tuna Thunnus albacares is a high value oceanic resource for which targeted fishing was initiated in 2008 in Lakshadweep islands. Pole and line, troll line and drift gillnet are the major gears operated in the islands using traditionally designed mechanised Pablo boats of 25 to 34 feet overall length. Fishing operation is mainly practised during September to May. The estimated landing of total fish from three islands of Lakshadweep (Minicoy, Androth and Agatti) during January–December, 2011 was 1555 t, of which tuna contributed 83%. Maximum yellowfin tuna landing was recorded from Minicoy (84%) followed by Agatti (9 %) and Androth (7%). Smaller sized yellowfin tuna with fork length (FL) measuring 42-46 cm were observed throughout the year. Swarming crab, Charybdis smithii was the dominant food component with index of relative importance (IRI) of 87.5 followed by Auxis thazard (IRI - 5.3) and Cheilopogon sp. (IRI - 0.8). Since the inception of the World Bank aided National Agricultural Innovation Project (NAIP) by the Indian Council of Agricultural Research (ICAR), on ’Developing a value chain for oceanic tunas in Lakshadweep islands’, targeted fishing for yellowfin tuna has resulted in 37% increase in the landing of this species.