Table 1: Stock status determination for Sandbar Shark
Jurisdiction |
Western Australia |
New South Wales, Queensland |
Stock |
Western Australian
(WCDGDLF, JASDGDLF) |
Eastern Australian
(ECIFFF, OTLF) |
Stock status |
↑ |
|
Transitional–recovering |
Undefined |
Indicators |
Catch, CPUE, age structure, direct estimates of fishing mortality |
None |
CPUE = catch per unit effort; ECIFFF = East Coast Inshore Fin Fish Fishery (Queensland); JASDGDLF = Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery; OTLF = Ocean Trap and Line Fishery (New South Wales); WCDGDLF = West Coast Demersal Gillnet and Demersal Longline Fishery (Western Australia)
Sandbar Shark occurs off the east and west coasts of Australia from approximately 17°S to 32°S off the east coast, and 13°S to 36°S off the west coast1. Due to the limited recorded catches in the Northern Territory and southern Australia, the species is considered to be represented by separate eastern and western biological stocks in Australian waters2. Status is reported at the biological stock level.
Western Australian biological stock
Sandbar Sharks are targeted in Western Australia by the West Coast Demersal Gillnet and Demersal Longline Fishery and are also taken in the Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery. They were previously targeted by the Western Australian North Coast Shark Fishery and the Joint Authority Northern Shark Fishery. The Western Australian stock assessment uses current and historical data from all these fisheries.
Because of the longevity of Sandbar Shark and the age-specific nature of targeted fishing mortality, a sufficiently long time series of data on catch per unit effort (CPUE) is not yet available for dynamic stock assessment modelling. Therefore, assessment of this biological stock has been undertaken using empirically derived estimates of fishing mortality and demographic modelling techniques3– 4.
The demographic model indicated that combined levels of fishing mortality in the targeted shark fisheries, non-target shark fisheries and recreational fishing sector became increasingly unsustainable between 2001 and 2004 (when catches peaked at 918 tonnes [t]), and possibly since 1997–985. This was supported by fishery-independent surveys that showed declines in CPUE between 2002 and 2005, which may be indicative of declining biomass5.
Expected reductions in recruitment caused by previously excessive catches are unlikely to be reflected in the CPUE data until cohorts born since 2004–05 enter the fishery at 6–9 years of age (i.e. over the coming three years). However, Sandbar Shark catches in 2008–09 (81 t) and 2009–10 (107 t) were within the levels deemed by the assessments to allow gradual recovery of the breeding stock5. Assessments also indicate that, in 2010, the spawning stock biomass is likely to be close to the minimum acceptable limit (40 per cent of the unfished biomass [B0])5. Current levels of fishing are considered suitably precautionary to ensure that the recovery of this biological stock is occurring.
On the basis of the evidence provided above, the biological stock is classified as a transitional–recovering stock.
Eastern Australian biological stock
In New South Wales, whaler sharks (Carcharhinus spp.), including Sandbar Shark have historically not been adequately identified and reported at the species level in commercial catch logbooks6. However, observer data indicates that Sandbar Shark is the dominant whaler shark species caught in the Ocean Trap and Line Fishery (New South Wales) (35 per cent of overall shark catch)7. The East Coast Inshore Fin Fish Fishery (Queensland) net and line fisheries contribute minimal quantities (<3 t per year) to the overall eastern Australian harvest of Sandbar Shark.
Insufficient information is available to determine the status for any of the whaler shark species in New South Wales, including Sandbar Shark8. Collaboration is currently under way with Fisheries Queensland to determine the stock structure of Sandbar Shark.
Insufficient information is available to confidently classify the status of this biological stock; therefore the biological stock is classified as an undefined stock.
Table 2: Sandbar Shark biology1,9–10
Longevity and maximum size |
~30–40 years; 166 cm FL |
Maturity (50%) |
Females: 16.2 years; 136 cm FL Males: 13.8 years; 127 cm FL |
FL = fork length
Figure 1: Distribution of reported commercial catch of Sandbar Shark in Australian waters, 2010
- Sandbar Sharks are taken commercially by demersal gillnets in Western Australia, and bymost hook fishing methods, including longlines and set lines, in New South Wales. To minimise commercial catches of larger whaler sharks, longline hook sizes were restricted in Western Australia, and metal snoods were prohibited in these fisheries in 2006. Most of the very limited recreational and charter fishing catches of Sandbar Shark are taken by lines (rod) with bait from the shore or boats.
- A range of input and output controls have been applied to Sandbar Shark across the three jurisdictions:
- Input controls include limited entry, gear restrictions, spatial closures and effort limits.
- Output controls include total allowable catches, and recreational size and bag limits.
- In 2010, Sandbar Shark catch was reported by 4 West Coast Demersal Gillnet and Demersal Longline Fishery (Western Australia) vessels and 22 Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery vessels. No fishing was reported for the northern shark fisheries (Western Australian Northern Shark Fishery and Joint Authority Northern Shark Fishery) in 2009–10. Fifty-eight vessels reported catching Sandbar Shark in the Ocean Trap and Line Fishery (New South Wales) in 2010. In the East Coast Inshore Fin Fish Fishery (Queensland) 3 line vessels and 1 net vessel reported catching Sandbar Shark in 2010.
- In 2009–10, the catch of Sandbar Shark was approximately 121 t, with 107 t caught in Western Australian fisheries, less than 3 t in the East Coast Inshore Fin Fish Fishery (Queensland) and 10.7 t in the Ocean Trap and Line Fishery (New South Wales).
- The annual recreational catch of combined whaler sharks in New South Wales is likely to be between 40 and 100 t. This estimate is based on the results of the National Recreational and Indigenous Fishing Survey11 and onsite surveys undertaken by the New South Wales Department of Primary Industries. The catch of Sandbar Shark within this total is unknown.
Figure 2: Commercial catch of Sandbar Shark in Australian waters, 2000–01 to 2010–11 (financial year)
The total commercial catch of Sandbar Shark in Western Australia in 2009–10 was 107 t, far less than the peak catch reported in 2004–05 of 918 t. Over the past three years (2007–08 to 2009–10), the catch of Sandbar Shark across Western Australia has declined from 253 t to 107 t, as a result of management controls aimed at improving levels of the spawning stock and associated shark fishery management objectives. There have been negligible reported landings of whaler sharks (including Sandbar Shark) by other Western Australian–managed fisheries since all sharks and rays were commercially protected in 2006.
In New South Wales, the most significant commercial catches of Sandbar Shark are in the Ocean Trap and Line Fishery as a key secondary species8. Sandbar Shark catches drove the dramatic increase (200 per cent) in New South Wales shark catches reported in 2006–07, peaking in a catch of 115 t in 2007–08. Analysis of the catch indicated that this increase was due to a 'new' component of the Ocean Trap and Line Fishery that targeted large whaler sharks off northern New South Wales. The New South Wales Department of Primary Industries therefore implemented specific conditions and restrictions on shark fishing (targeted or otherwise) in the Ocean Trap and Line Fishery during 2008–09 that included a total allowable commercial catch (TACC) for large shark (i.e. whaler, hammerhead and mackerel shark) species, maximum catch limits for individual TACC shark fishing trips, and a restricted permit for fishers specifically targeting Sandbar Sharks. The reported catch declined to 10.7 t in 2009–10.
- A recent analysis of potential changes in the ecosystem structure of the south and west coasts of Western Australia12 found no evidence of any systematic change in species diversity richness or trophic level, indicating that this fishery is not having a material impact on the food chain or trophic structure.
- The demersal gillnets and longlines used to catch Sandbar Shark do not significantly impact on benthic habitats where the gear is set—usually away from reefs to avoid damage to nets5. However, they do have the potential to interact with threatened and endangered species.
- Climate change and climate variability have the potential to impact fish stocks in a range of ways, including influencing their geographic distribution (e.g. latitudinal shifts in distribution). However, it is unclear how climate change may affect risks to sustainability.
a Department of Fisheries, Western Australia
b Department of Primary Industries, New South Wales
c Department of Agriculture, Fisheries and Forestry, Queensland