Commonly discarded fishes on Indonesian tuna longline fishery in Indian Ocean

Incidental by-catch and associated discarding are difficult to estimate on the basis of logbook information because they are poorly reported by fishing masters and their importance varies with several interrelated factors. The purpose of this paper is to inform the commonly discarded fishes on the Indonesian tuna longline fishery in the Indian Ocean. The study was conducted during 2010 – 2011 following six commercial tuna longline vessels based in Port of Benoa. The results showed that discards composition reach almost 20% from total catch. Those discards composition was dominated by longnose lancetfish (32.73%) and pelagic stingrays (11.62%) which both species contribute almost half of total discards. Later followed by crocodile shark (6.07%), snake mackerel (0.41%), ocean sunfish (0.14%), olive ridley turtle (0.07%), with hammerhead shark, tappertail ribbonfish, false killer whale and leatherback sea turtle 0.02% each. Almost half of total catch are discards and half of discards are disposed dead or dying. These findings indicate the need for special management to reduce the discards for tuna longline in Indonesia.