Table 1: Stock status determination for Swordfish
Jurisdiction |
Commonwealthb |
Stock |
Indian Ocean
(IOTC, WTBF) |
Pacific Oceanc
(ETBF, WCPFC) |
Stock status |
|
|
Sustainable |
Sustainable |
Indicators |
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 and Pacific Oceans are considered to comprise two distinct biological stocks of Swordfish. Research in the Indian Ocean is examining the possibility that two Indian Ocean biological stocks exist in the south-west and south-east Indian Ocean1. However, as this study
is still in progress, there is currently no strong evidence for another biological stock, and status determination is undertaken at the management unit level (i.e. Indian Ocean). In the Pacific Ocean, genetic studies have suggested the presence of several semi-independent biological stocks2. However, the delineation of these biological stocks is unknown, and sample sizes were relatively low2. Hence, status is reported at the management unit level (i.e. Pacific Ocean). The Indian Ocean management unit is under the jurisdiction of the Indian Ocean Tuna Commissiona+. The Pacific Ocean management unit is under the jurisdiction of the Western and Central Pacific Fisheries Commissionb+.
The data used to determine status are from 2007 or 2008, because of lags in reporting catch data to the Indian Ocean Tuna Commission and the Western and Central Pacific Fisheries Commission. In addition, the stock assessment for the Pacific Ocean has not been updated since 2008.
Indian Ocean management unit
This management unit 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 stock assessment3 estimated that biomass of the Swordfish stock in 2008 was 42 per cent of initial unfished biomass and above the biomass at maximum sustainable yield (MSY) (113 per cent of MSY). The management unit is therefore unlikely to be recruitment overfished. This assessment also estimated that fishing mortality in 2008 was below the level associated
with MSY (70 per cent of mortality at MSY). This level of fishing mortality is unlikely to cause the management unit to become recruitment overfished.
On the basis of the evidence provided above, the Indian Ocean management unit is classified as a sustainable stock.
Pacific Ocean management unit
This management unit 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 south-west Pacific Ocean, the most recent assessment2 estimated that spawning stock biomass of the Swordfish stock in 2007 was well above the biomass at MSY (198 per cent of MSY). The management unit is therefore unlikely to be recruitment overfished. This assessment
also estimated that fishing mortality was well below the level associated with MSY (44 per cent of mortality at MSY). This level of fishing mortality is unlikely to cause the management unit to become recruitment overfished.
On the basis of the evidence provided above, the Pacific Ocean management unit is classified as a sustainable stock.
Table 2: Swordfish biology2,4–5
Longevity and maximum size |
30+ years; 455 cm FL |
Maturity (50%) |
Females: 6–7 years; ~170 cm FL Males: 1–3 years; ~120 cm FL |
FL = fork length (measured from the lower jaw for Swordfish)
Figure 1: Distribution of reported commercial catch of Swordfish in Australian fisheries, 2010
- Pelagic longline is used to fish for Swordfish in Australia and globally.
- In Australia, Swordfish 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 in 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 commercial longline vessels and 1 active commercial minor-line vessel that caught Swordfish in 2010; in the whole Indian Ocean Tuna Commission Area of Competence, 3947 commercial vessels and several thousand artisanal vessels were active in 2009. In the Eastern Tuna and Billfish Fishery (Commonwealth), there were 54 active commercial longline vessels and 3 active commercial minor-line vessels that caught Swordfish in 2010; in the whole Western and Central Pacific Fisheries Commission Convention Area, 5274 commercial vessels and several thousand artisanal vessels were active in 2009.
- Australian catch in the Western Tuna and Billfish Fishery (Commonwealth) for the 2010 calendar year was 349 tonnes (t). Total Swordfish catches in the Indian Ocean Tuna Commission area for
2009 were 21 860 t.
- Australian catch in the Eastern Tuna and Billfish Fishery (Commonwealth) for the 2009–10 fishing season was 1144 t. Total Swordfish catches in the Western and Central Pacific Fisheries Commission area for 2009 were 19 821 t. Estimates of Australian recreational and Indigenous catch are unavailable.
Figure 2: Commercial catch of Swordfish in the Western and Central Pacific Fisheries Commission and Indian Ocean Tuna Commission areas, 1970–2009 (calendar year)
Catch data from the Western and Central Pacific Fisheries Commission and the Indian Ocean Tuna Commission are reported for 2009, as this information was used to determine stock status in 2010. In the Western and Central Pacific Fisheries Commission area, catches of Swordfish have generally increased since the 1970s, although the catch in 2009 was lower than in recent years. In the Indian Ocean Tuna Commission area, catches peaked in 2004 but have declined since then, probably as
a result of piracy in the western Indian Ocean1,3. Australian Swordfish catches have been relatively stable for several years in both the Western Tuna and Billfish Fishery (Commonwealth) and the Eastern Tuna and Billfish Fishery (Commonwealth) and comprise a small percentage of the catch taken in the Indian and Pacific Oceans, respectively. Commonwealth catch of Swordfish peaked at
2163 t in 2002 in the Eastern Tuna and Billfish Fishery and 2136 t in 2001 in the Western Tuna and
Billfish Fishery.
- Following completion of Ecological Risk Assessments in the Western Tuna and Billfish Fishery (Commonwealth), no species were identified as high risk6. 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 turtle7–8.
- 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.
- Studies have indicated that the distribution and abundance of Tuna, and possibly Billfish, can be affected by environmental factors9–10.
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.
c The Indian Ocean Tuna Commission and the Western and Central Pacific Fisheries Commission are intergovernmental organisations established to manage a number of highly migratory fish species.
a+ www.iotc.org
b+ www.wcpfc.int