Table 1: Stock status determination for Yellowfin Tuna
Jurisdiction |
Commonwealthb |
Stock |
Indian Ocean
(IOTC, WTBF) |
Pacific Oceanb+
(ETBF, WCPFC) |
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)
The Indian Ocean and western and central Pacific Ocean are considered to comprise two distinct biological stocks. In the Indian Ocean, tagging studies have shown large movements of Yellowfin Tuna and support the assumption of a single biological stock1. A single biological stock is considered to exist in the western and central Pacific Ocean2. The Indian Ocean biological stock is under the jurisdiction of the Indian Ocean Tuna Commissiona+. The Pacific Ocean biological stock is under the jurisdiction of the Western and Central Pacific Fisheries Commissionb+.
The data used to determine stock status are from 2008 or 2009, because of lags in reporting catch data to the Indian Ocean Tuna Commission and the Western and Central Pacific Fisheries Commission.
Indian Ocean biological stock
This 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 2010 stock assessment3 estimated that the spawning biomass of the Yellowfin Tuna biological stock in 2009 was 33 per cent of initial unfished biomass. The biological stock is not considered to be recruitment overfished. This assessment also estimated that fishing mortality in 2009 was at the level associated with maximum sustainable yield (MSY) (99 per cent of mortality at MSY). This level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished.
On the basis of the evidence provided above, the Indian Ocean biological stock is classified as a sustainable stock.
Pacific Ocean biological stock
This 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 Pacific Ocean, the stock assessment2 estimated that biomass of the Yellowfin Tuna biological stock in 2008 was 42–57 per cent of initial unfished biomass. The biological stock is not considered to be recruitment overfished. This assessment also estimated that fishing mortality in 2008 was below the level associated with MSY (54–68 per cent of mortality at MSY). This level of fishing mortality is unlikely to cause the biological stock to become recruitment overfished.
On the basis of the evidence provided above, the Pacific Ocean biological stock is classified as a sustainable stock.
Table 2: Yellowfin Tuna biology4
Longevity and maximum size |
9 years; ~180 cm FL |
Maturity (50%) |
~2 years; 100 cm FL |
FL = fork length
Figure 1: Distribution of reported commercial catch of Yellowfin Tuna in Australian fisheries, 2010
- Globally and in Australia, Yellowfin Tuna is fished using longline. Outside of Australia, juvenile Yellowfin Tuna are also captured in purse-seine fisheries targeting Skipjack Tuna, especially when fish-aggregating devices are deployed.
- In Australia, Yellowfin Tuna is managed using a range of input and output controls:
- Input controls include limited entry to the fishery through longline and minor-line boat statutory fishing rights, as well as gear and area restrictions.
- Output controls include total allowable commercial catches. These were in place for the Western Tuna and Billfish Fishery (Commonwealth) in 2010 and have been implemented in the Eastern Tuna and Billfish Fishery (Commonwealth) since March 2011.
- In the Western Tuna and Billfish Fishery (Commonwealth), there were 3 active longline vessels and 1 active minor-line vessel that caught Yellowfin Tuna in 2010; in the whole Indian Ocean Tuna Commission Area of Competence, 3947 industrial vessels and several thousand artisanal vessels were active in 2009 (figures are not available for 2010). In the Eastern Tuna and Billfish Fishery (Commonwealth), there were 54 active longline vessels and 3 active minor-line vessels that caught Yellowfin Tuna in 2010; in the whole Western and Central Pacific Fisheries Commission Convention Area, 5274 industrial vessels and several thousand artisanal vessels were active in 2009 (figures are not available for 2010).
- Australian commercial catch of Yellowfin Tuna in the Western Tuna and Billfish Fishery (Commonwealth) for the 2010 calendar year was 22 tonnes (t). Total Yellowfin Tuna catches in the Indian Ocean Tuna Commission area for 2009 were 289 906 t.
- Australian commercial catch of Yellowfin Tuna in the Eastern Tuna and Billfish Fishery (Commonwealth) for the 2009–10 fishing season was 1541 t. Total Yellowfin Tuna catches in the Western and Central Pacific Fisheries Commission area for 2009 were 433 275 t.
- Yellowfin Tuna are caught by recreational anglers, but estimates of Australian recreational and Indigenous catch are not available.
Figure 2: Commercial catch of Yellowfin Tuna in the Western and Central Pacific Fisheries Commission and the Indian Ocean Tuna Commission areas, 1970–2009 (calendar year)
Although catches of Yellowfin Tuna in both the Western and Central Pacific Fisheries Commission area and the Indian Ocean Tuna Commission area have generally increased with growing demand and effort, catch in the latter area has decreased over the past several years as a result of piracy in the western Indian Ocean. Peak catch of Yellowfin Tuna in Australia was 3158 t in 2003 for the Eastern Tuna and Billfish Fishery (Commonwealth) and 567 t in 2001 for the Western Tuna and Billfish Fishery (Commonwealth).
- Following completion of Ecological Risk Assessments in the Western Tuna and Billfish Fishery (Commonwealth), no species were identified as high risk5. 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 turtle6–7.
- 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.
- Australia has prohibited the practice of shark finning in longline fisheries managed by the Commonwealth and the use of wire traces in these fisheries, to reduce fishery impacts on sharks.
- The distribution and abundance of tuna can be affected by environmental factors8–9. For example, seasonal changes in the abundance of Bigeye and Yellowfin Tuna on the east coast of Australia are linked to the expansion and contraction of the East Australian Current10.
a Australian Bureau of Agricultural and Resource Economics and Sciences
b Information related to management arrangements in Australian fisheries has been updated to be current for 2012.
a+ www.iotc.org
b+ www.wcpfc.inf