Table 1: Stock status determination for Yellowfin Tuna
Jurisdiction |
Commonwealth |
Stock |
Indian Ocean
(WTBF, IOTCb) |
Western and central Pacific Ocean
(ETBF, WCPFCb) |
Stock status |
|
|
Sustainable |
Sustainable |
Indicators |
Spawning stock biomass, fishing mortality |
Spawning stock biomass, fishing mortality |
ETBF = Eastern Tuna and Billfish Fishery (Commonwealth); IOTC = Indian Ocean Tuna Commission; WCPFC = Western and Central Pacific Fisheries Commission; WTBF = Western Tuna and Billfish Fishery (Commonwealth)
b The Indian Ocean Tuna Commission (www.iotc.org) and the Western and Central Pacific Fisheries Commission (www.wcpfc.int) are intergovernmental organisations established to manage a number of highly migratory fish species.
Yellowfin Tuna in the Indian Ocean, and western and central Pacific Ocean are considered to be two distinct biological stocks, which are managed under separate regional fisheries management organisations. In the Indian Ocean, although there is some evidence for stock structure that requires further investigation1, tagging studies have indicated large movements of Yellowfin Tuna, supporting the assumption of a single biological stock2. A single biological stock is considered to exist in the western and central Pacific Ocean3. The Indian Ocean biological stock is under the jurisdiction of the Indian Ocean Tuna Commission. The western and central Pacific Ocean stock is under the jurisdiction of the Western and Central Pacific Fisheries Commission.
Data used to determine stock status differ depending on the assessment, because of delays in reporting catch data to the Indian Ocean Tuna Commission, and the Western and Central Pacific Fisheries Commission. Data for the Indian Ocean assessment were from 1950 to 2011, or 1972 to 20114 (multiple assessments were undertaken). Data for the Pacific Ocean assessment were from 1952 to 2012.
Indian Ocean biological stock
The Indian Ocean biological stock is fished by Australian fishers endorsed to fish in the Western Tuna and Billfish Fishery (Commonwealth), and numerous other international jurisdictions. The assessments undertaken by the Indian Ocean Tuna Commission take into account information from all jurisdictions.
In the Indian Ocean, the 2012 stock assessments4 estimated (over the range of plausible models investigated) that the spawning biomass of the Yellowfin Tuna biological stock in 2010 was 38 per cent of the initial unfished biomass and above the biomass level that would produce maximum sustainable yield (MSY) in the long term. The biological stock is not considered to be recruitment overfished5. The assessments also estimated that current (2010 or 2011) fishing mortality was below the level associated with MSY (61–69 per cent of mortality at MSY). This level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished5.
On the basis of the evidence provided above, the biological stock is classified as a sustainable stock.
Western and central Pacific Ocean biological stock
The western and central Pacific Ocean biological stock is fished by Australian fishers endorsed to fish in the Eastern Tuna and Billfish Fishery (Commonwealth), and numerous other international jurisdictions. The assessments undertaken for the Western and Central Pacific Fisheries Commission take into account information from all jurisdictions.
In the western and central Pacific Ocean, the stock assessment3 estimated that the current (2008 to 2011) spawning biomass of the Yellowfin Tuna biological stock was 42 per cent of the initial unfished biomass and above the level that would produce MSY. The biological stock is not considered to be recruitment overfished6. This assessment also estimated that current fishing morality was below the level associated with MSY (72 per cent of mortality at MSY). This level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished6.
On the basis of the evidence provided above, the biological stock is classified as a sustainable stock.
Table 2: Yellowfin Tuna biology7
Longevity and maximum size |
9 years; ~1800 mm FL |
Maturity (50%) |
~2 years; 1000 mm FL |
FL = fork length
Figure 1: Distribution of reported commercial catch of Yellowfin Tuna in Australian Fisheries, 2013 (calendar year)
Table 3: Main features and statistics for Yellowfin Tuna fisheries in Australia, 2013 (calendar year)
Jurisdiction |
Commonwealth (Indian Ocean) |
Commonwealth (western and central Pacific Ocean) |
Fishing methods |
Commercial |
Pelagic longline |
✓ |
✓ |
Minor lines (for example, hand line, troll, rod and reel) |
✓ |
✓ |
Purse seine |
✓ |
|
Recreationala,b |
Rod and reel |
✓ |
✓ |
Spearfishing |
|
✓ |
Indigenousb,c |
|
Unknown |
Unknown |
Management methods |
Commercial |
Limited entry |
✓ |
✓ |
Gear restrictions |
✓ |
✓ |
Area restrictions |
✓ |
|
Catch limits |
✓ |
✓ |
Individual transferable quotas |
✓ |
✓ |
Recreationala,b |
Bag limits |
✓ |
✓ |
Boat limits |
✓ |
|
Indigenousb,c |
|
None |
None |
Active vessels |
|
4 in WTBF
Unknown in IOTC |
40 in ETBF
Unknown in WCPFC |
Catchd |
Commercial |
40 t in WTBF
365 826 t in IOTC |
1341 t in ETBF
646 165 t in WCPFC |
Recreational |
Unknown |
Unknown |
Indigenous |
Unknown |
Unknown |
Markets |
Domestic |
✓ |
✓ |
Export |
✓ |
✓ |
ETBF = Eastern Tuna and Billfish Fishery (Commonwealth); IOTC = Indian Ocean Tuna Commission; WCPFC = Western and Central Pacific Fisheries Commission; WTBF = Western Tuna and Billfish Fishery (Commonwealth)
a The Australian Government does not manage recreational fishing in Commonwealth waters. Recreational fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters, under its management regulations.
b Recreational and Indigenous fishing sectors in the Indian Ocean are Western Australia, South Australia and Victoria; recreational sectors in the Pacific Ocean are Queensland, New South Wales and Tasmania. A tick indicates that a measure exists in one of these jurisdictions.
c The Australian Government does not manage noncommercial Indigenous fishing in Commonwealth waters, with the exception of the Torres Strait. In general, noncommercial Indigenous fishing in Commonwealth waters is managed by the state or territory immediately adjacent to those waters.
d Catches reported for the IOTC and WCPFC are for 2012, the most recent year available.
Figure 2: Commercial catch of Yellowfin Tuna in the Western and Central Pacific Fisheries Commission and Indian Ocean Tuna Commission areas, 1970 to 2012 (calendar years)
Following completion of ecological risk assessments (levels 1–3) in the Western Tuna and Billfish Fishery (Commonwealth), no species were identified as high risk8. In the Eastern Tuna and Billfish Fishery (Commonwealth), a total of nine species were identified as being at high risk or precautionary high risk. This is the priority list of species for attention under the Eastern Tuna and Billfish Fishery ecological risk management strategy; it includes two species of sunfish, four species of shark, two species of cetacean and one species of marine turtle 9,10.
No target species, ecological communities or habitats were assessed to be at high risk from the effects of fishing in the Eastern Tuna and Billfish Fishery (Commonwealth) or Western Tuna and Billfish Fishery (Commonwealth).
Australia implements regulations to minimise the environmental impact of fisheries for tuna and tuna-like species on pelagic ecosystems, specifically on seabirds, sea turtles and sharks. Both the Indian Ocean Tuna Commission and the Western and Central Pacific Fisheries Commission have passed conservation and management measures that are broadly consistent with each other and with Australia’s domestic requirements.
To reduce fishery impacts on sharks, Australia has prohibited the practice of shark finning and the use of wire leaders11 in longline fisheries managed by the Commonwealth.
- The distribution and abundance of tuna can be affected by environmental factors12,13. For example, seasonal changes in the abundance of Bigeye Tuna and Yellowfin Tuna on the east coast of Australia are linked to the expansion and contraction of the East Australian Current14.
a Australian Bureau of Agricultural and Resource Economics and Sciences