Slender tuna (Allothunnus fallai Serventy): first record of bulk catches, Tasmania, 1974

Abstract

Purse seine catches of 230 tonnes of slender tuna in Tasmania were made in June 1974. The species has heretofore been regarded as rare in Australian waters, and relatively uncommon elsewhere. Surface water temperatures during commercial fishing ranged from 12.0 to 14.0ºC. Age estimations by otoliths suggested 4+ to 6+ years for lengths 69.0-91.0 cm. The length-weight relationship was W = 0.000004SL^3.322. The tuna were feeding mainly on pelagic Crustacea. Gonad inspection showed that spawning had occurred recently. Three internal parasites (Anisakis sp., Copepoda, Cestoda) were found in 89.3, 95.7 and 61.7% of the 46 fish examined. Fish flesh was extremely oily (10-50%), and mercury analysis gave readings from 0.1 to 0.2 mg/kg.