Sandbar Shark (2018)
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Sandbar Shark occurs primarily off both the east and west coasts of Australia. The eastern Australian stock is undefined and the Western Australian stock is recovering.
Stock Status Overview
|Northern Territory||Western Australia||ONLF||Recovering||Catch, CPUE , fishing mortality|
- Offshore Net and Line Fishery (NT)
Sandbar Shark (Carcharhinus plumbeus) occurs primarily off both the east and west coasts of Australia, from approximately latitude 17–32°S off the east coast, and latitude 13–36°S off the west coast [Last and Stevens 2009, McAuley et al. 2007]. The species is also encountered off the northern Australian coast, although in much lower numbers. In addition to genetic analysis that suggests limited gene flow between eastern and western Sandbar Shark stocks [Portnoy et al. 2010], there are limited recorded catches in the Gulf of Carpentaria and southern Australia. Thus, the species is considered to be represented by separate Eastern and Western biological stocks in Australian waters.
Here, assessment of stock status is presented at the biological stock level—Western Australia and Eastern Australia.
In Western Australia, Sandbar Shark is targeted by the West Coast Demersal Gillnet and Demersal Longline Fishery, and taken in lesser quantities by the Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery [McAuley et al. 2015]. It was also previously targeted by the Western Australian North Coast Shark Fishery [McAuley and Rowland 2012]. The Western Australia stock assessment uses current and historical data from all of these fisheries. Minor catches historically reported from the Offshore Net and Line Fishery (Northern Territory) are assumed to be from the Western Australia biological stock, as is an unquantified catch from the Memorandum of Understanding Box Shark Fishery [Marshall et al. 2016]. These are not explicitly included in assessments of this stock.
Given the longevity of Sandbar Shark (30–40 years) and the age-specific nature of targeted fishing mortality (mostly between 2 and 10 years of age), a sufficiently long time-series of catch per unit effort data is not yet available for dynamic stock assessment modelling. Assessment of this stock has therefore been undertaken using empirically derived estimates of fishing mortality between 2001 and 2004, and demographic modelling techniques [McAuley et al. 2005, McAuley et al. 2007]. In addition, a risk-based weight of evidence (WoE) approach has been adopted using all available lines of evidence, including simulated biomass trajectories derived from a combination of demographic modelling and catch-only stock reduction analysis [Braccini et al. in prep.]. Demographic modelling indicated that combined levels of fishing mortality in Western Australian targeted shark fisheries, non-target commercial fisheries and the recreational fishing sector became increasingly unsustainable between 2001 and 2004 (when catches peaked at 918 tonnes [t]) and had probably exceeded sustainable levels since 1997–98. These conclusions are supported by fishery-independent survey data that indicated declining breeding stock abundance between 2002 and 2005 [McAuley and Rowland 2012, McAuley et al. 2005].
Since 2010, Sandbar Shark catches have remained well below the levels that will allow a gradual recovery of the breeding stock [McAuley et al. 2015]. The expected reductions in recruitment from previously excessive exploitation of the breeding stock are likely to be ameliorated by significant reduction in targeted fishing effort. Therefore, although the breeding stock is considered to be close to the minimum acceptable limit (40 per cent of unfished biomass), current levels of fishing are considered suitably precautionary to ensure the recovery of this biological stock [McAuley et al. 2015].
The recent WoE assessment estimated a “Medium” current risk level for the sandbar shark stock, with 62 per cent, 83 per cent and 99 per cent of the simulated current (2015–16) relative total biomass trajectories being above the target, threshold and limit biomass reference points, respectively, and biomass projections indicating continued stock rebuilding under current fishing and management settings [Braccini et al. in prep.].
The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to have been impaired. However, available indicators suggest a recovering stock. The current level of fishing mortality should allow the stock to recover from its recruitment impaired state.
On the basis of the evidence provided above, the Western Australia biological stock is classified as a recovering stock.
Sandbar Shark biology [Geraghty et al. 2013, McAuley et al. 2007, McAuley et al. 2006]
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|Sandbar Shark||30–40 years, 1 660 mm FL, 2 150 mm TL||Females: 16.2 years, 1 360 mm FL Males: 13.8 years, 1 270 mm FL|
|Hook and Line|
|Indigenous||Unknown but likely to be negligible|
|Recreational||Unknown but likely to be negligible|
Western Australia – Recreational (Management methods) A recreational fishing from boat licence is required for recreational fishing from a powered vessel in Western Australia.
Queensland – Indigenous Under the Fisheries Act 1994 (Qld), Indigenous fishers in Queensland are able to use prescribed traditional and non-commercial fishing apparatus in waters open to fishing. Size and possession limits, and seasonal closures do not apply to Indigenous fishers. Further exemptions to fishery regulations may be applied for through permits.
New South Wales – Indigenous (Management Methods) (a) Aboriginal Cultural Fishing Interim Access Arrangement—allows an Indigenous fisher in New South Wales to take in excess of a recreational bag limit in certain circumstances; for example, if they are doing so to provide fish to other community members who cannot harvest for themselves, (b) The Aboriginal cultural fishing authority is the authority that Indigenous persons can apply to take catches outside the recreational limits under the Fisheries Management Act 1994 (NSW), Section 37 (1d)(3)(9), Aboriginal cultural fishing authority, and (c) In cases where the Native Title Act 1993 (Cth) applies fishing activity can be undertaken by the person holding native title in line with S.211 of that Act, which provides for fishing activities for the purpose of satisfying their personal, domestic or non-commercial communal needs. In managing the resource where native title has been formally recognised, the native title holders are engaged with to ensure their native title rights are respected and inform management of the State's fisheries resources
New South Wales commercial fisheries with less than seven active fishers are not presented due to the Privacy Act.
Recreational and Indigenous (catch) Given the offshore distribution of Sandbar Shark, near-shore catches are likely to be negligible.
- Braccini, M, Hesp, A, Molony, B and Blay, N in prep Resource Assessment Report Whiskery, Gummy, Dusky and Sandbar Shark Resource of Western Australia. Department of Primary Industries and Regional Development.
- Geraghty PT, Macbeth, WG, Harry, AV, Bell, JE, Yerman, MN and Williamson, JE 2013, Age and growth parameters for three heavily exploited shark species off temperate eastern Australia, ICES Journal of Marine Science, 71: 559–573.
- Last, PR and Stevens, JD 2009, Sharks and rays of Australia, 2nd edn, CSIRO Publishing, Collingwood.
- Macbeth, WG, Butcher, PA, Collins, D, McGrath, SP, Provost, SC, Bowling, AC, Geraghty, PT and Peddemors, VM 2018, Improving reliability of species identification and logbook catch reporting by commercial fishers in an Australian demersal shark longline
- Macbeth, WG, Geraghty, PT, Peddemors, VM and Gray, CA 2009, Observer-based study of targeted commercial fishing for large shark species in waters off northern New South Wales, Fisheries final report series 114, Industry and Investment New South Wales, Cronulla.
- Marshall L, Giles, J and Johnson, GJ 2016, Catch composition of a traditional Indonesian shark fishery operating in the MOU Box, northwestern Australia: Results of shark fin identification from Operation Snapshot (May 2015), Australian Fisheries Management Authority, Canberra.
- McAuley, R and Rowland, F 2012, Northern Shark Fisheries status report, in WJ Fletcher and K Santoro (eds), Status reports of the fisheries and aquatic resources of Western Australia 2011/12, Western Australian Department of Fisheries, Perth, 222–227.
- McAuley, R, Braccini, M, Newman, SJ and O’Malley, J 2015, Temperate Demersal Gillnet and Demersal Longline Fisheries Status Report, in WJ Fletcher and K Santoro (eds), Status Reports of the Fisheries and Aquatic Resources of Western Australia 2014/15, Western Australian Department of Fisheries, Perth, 261–272.
- McAuley, R, Lenanton, R, Chidlow, J, Allison, R and Heist, E 2005, Biology and stock assessment of the Thickskin (Sandbar) Shark, Carcharhinus plumbeus, in Western Australia and further refinement of the Dusky Shark, Carcharhinus obscurus, stock assessment, final report to the Fisheries Research and Development Corporation, project 2000/134, Fisheries research report 151, Western Australian Department of Fisheries, Perth.
- McAuley, RB, Simpfendorfer, CA and Hall, NG 2007, A method for evaluating the impacts of fishing mortality and stochastic influences on the demography of two long-lived shark stocks, ICES Journal of Marine Science, 64: 1710–1722.
- McAuley, RB, Simpfendorfer, CA, Hyndes, GA and Lenanton, RCJ 2007, Distribution and reproductive biology of the Sandbar Shark, Carcharhinus plumbeus, (Nardo, 1827) in Western Australian waters, Marine and Freshwater Research, 58: 116–126.
- McAuley, RB, Simpfendorfer, CA, Hyndes, GA, Allison, RR, Chidlow, JA, Newman, SJ and Lenanton, RCJ 2006, Validated age and growth of the sandbar shark, Carcharhinus plumbeus (Nardo, 1827) in the waters off Western Australia, Environmental Biology of Fishes, 77: 385–400.
- Portnoy, DS, McDowell, JR, Heist, EJ, Musick, JA and Graves, JE 2010, World phylogeography and male-mediated gene flow in the Sandbar Shark, Carcharhinus plumbeus, Molecular Ecology, 19: 1994–2010.
- Rowling, KA, Hegarty, A and Ives, M 2010, Status of fisheries resources in NSW 2008/09, Industry and Investment New South Wales, Cronulla.