Longtail Tuna (Thunnus Tonggol)

I & I NSW Wild Fisheries research Program Longtail Tuna (Thunnus tonggol)

Exploitation Status Undefined

A coastal tuna species for which the recreational fishery is probably more significant than the commercial fishery. There are few useful data with which to establish status.

Scientific name Standard name comment Previously, but incorrectly called northern Thunnus tonggol longtail tuna bluefin tuna.

Thunnus tonggol Image © Bernard Yau

Background The longtail tuna reaches maturity at lengths of around 60-70 cm, and spawning takes place The longtail tuna (Thunnus tonggol) inhabits during the summer months. The main diet of continental shelf and ocean waters in warm the longtail tuna consists of small pelagic and temperate and tropical regions of the Indo-west demersal fish, but also includes crustaceans and Pacific. It is a common species in Queensland cephalopods. waters but during the summer it can be found as far south as Twofold Bay in southern NSW. Because of their rapid acceleration, longtail Previously called ‘northern bluefin tuna’ in tuna are highly regarded as sports fish but Australia, the longtail tuna is a relatively small, their very dark flesh gives them a low market slender species that grows to a weight of acceptance. Since about 2000 the NSW 36 kg and length of 136 cm; it is more commercial catch has been less than 2 t per commonly 80-90 cm and 10-15 kg. In year, with most taken by the Ocean Trap and comparison, the true ‘northern bluefin’ (Thunnus Line Fishery and very small amounts reported orientalis) can exceed 500 kg in weight and by the Ocean Hauling and Estuary General reach almost 300 cm in length. Fisheries.

status of fisheries resources in nsw, 2008/09 Longtail Tuna | p 189 wild fisheries research program

Growth Curve of Longtail Tuna Additional Notes 100 • The fishery mostly occurs off Queensland

- data from the gamefish tagging program 90 show 93% of longtail tuna have been tagged off Queensland and 7% off NSW. 80

• Growth parameters are summarised in 70 Griffithset al. (2009) for samples from FL (cm) 60 Australia, Papua New Guinea and Japan. • The sporadic nature of catches off NSW 50

precludes the easy collection of additional 40 data. 30 • There is a combined recreational bag limit of 0 5 10 15 20 5 fish under 90 cm total length (TL) and 2 fish Age (years) over 90 cm TL for all tuna species. Growth curve of longtail tuna using parameters from Griffithset al. (2009). Lengths are presented as fork length (FL). Catch Further Reading Recreational Catch of Longtail Tuna Chow, S., N. Nakagawa, N. Suzuki, H. Takeyama and The annual recreational harvest of longtail tuna T. Matsunaga (2006). Phylogenetic relationships in NSW is likely to be less than one tonne. among Thunnus species inferred from rDNA ITS1 sequence. Journal of Fish Biology 68: 24-35. Collette, B.B. and C.E. Nauen (1983). Scombrids of the World. An Annotated and Illustrated Catalogue of Tunas, Mackerels, Bonitos and Related Species Historical Landings of Longtail Tuna Known to Date. Rome, FAO: 137 pp. Grant, E.M. (1982). Guide to Fishes. Brisbane,

6 Department of Harbours and Marine.

5 Griffiths, S.P., G.C. Fry, F.J. Manson and R.D. Pillans (2007). Feeding dynamics, consumption rates and

4 daily ration of longtail tuna (Thunnus tonggol) in Australian waters, with emphasis on the 3 consumption of commercially important prawns. Landings (t) Marine and Freshwater Research 58: 376-397. 2 Griffiths, S.P., C.F. Gary, Fiona J. M. and C.L. Dong 1 (2009). Age and growth of longtail tuna (Thunnus tonggol) in tropical and temperate waters of the 0 central Indo-Pacific. ICES Journal of Marine Science 93/94 95/96 97/98 99/00 01/02 03/04 05/06 07/08 67: 125-134 Financial Year Commercial landings (including available historical Hutchins, B. and R. Swainston (1999). Sea Fishes of records) of longtail tuna for NSW from 1992/93 to Southern Australia - Complete Field Guide for 2008/09 for all fishing methods. Financial years where Anglers and Divers. Smithfield, NSW, Gary Allen Pty commercial catch is made up of less than six fishermen Ltd. were removed due to privacy concerns. Lyle, J. M. and A. D. Read. (1985). Tuna in Northern Australian Waters: A preliminary appraisal. Darwin, Department of Ports and Fisheries. 41pp. Yearsley, G.K., P.R. Last and R.D. Ward (1999). Australian Seafood Handbook. Hobart, CSIRO Marine Research.

Please visit the CSIRO website, http://www.marine.csiro.au/caab/ and search for the species code (CAAB) 37 441013, common name or scientific name to find further information.

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Disclaimer: The information contained in this publication is based on knowledge and understanding at the time of writing (April 2010). However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of Industry and Investment NSW or the user’s independent adviser. p 190 | Longtail Tuna