Taxonomy
- The Tongol Tuna (Thunnus tonggol) is a smaller member of the Thunnus genus, which includes other species of tuna. It is also commonly known as the longtail tuna or northern bluefin tuna.
Species
of Commercial Interest
- The designation “Tongol Tuna” refers to a single species, Thunnus tonggol.
Distribution
- This Indo-West Pacific species is found from the Red Sea and East Africa to Papua New Guinea, north to Japan, and south to Australia. The population does not appear to be continuous.
Biology
- Tongol tuna are one of the lesser-studied tuna species, and little is known about their populations structure or basic biology. However, adequate knowledge may soon prove necessary, as this species is gaining popularity as a slightly moister alternative to albacore (white) tuna.
- This species is pelagic and oceanodromous (migratory). It is a predominantly neritic species, meaning that it associated with near-shore waters. It does, however, tend to avoid very turbid waters and areas with reduced salinity (such as estuaries). It may form schools of varying size, and younger individuals have been shown to forage in groups while adults forage individually. They feed on a variety of fishes, cephalopods, and crustaceans, particularly prawns.
- Tongol tunas probably spawn more than once a year, perhaps in two spawning seasons in the Gulf of Thailand. Spawning of this species is reported to be confined to coastal waters, based on the occurrence of their larvae which were collected at the water's surface. It appears there are two distinct spawning seasons for this species off the west coast of Thailand: a major spawning period from January to April and a minor spawning period from August-September. Spawning is also apparently seasonal for this species off Papua New Guinea and off New South Wales, occurring during the austral (southern) summer.
Sustainability
- IUCN Red List Status: Data Deficient (DD)
- MBA
Seafood Watch:
- Over 90 percent of Tongol tuna in the market comes from four nations: Indonesia, Iran, Malaysia and Thailand. All have numerous management measures in place to help protect populations, but Malaysia is the only one that also has adequate enforcement.
- Tuna caught with gear such as trolls, handlines, or pole gear is more selective, and tongol tuna caught these ways are preferred. Tongol tuna caught using all other gear (including gillnets and purse seines) has high bycatch of sharks and juvenile fishes.
Potential Health Concerns
- No notable health concerns at present. However, this may be due to a lack of data.
References
