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Sandbar Shark (2023)

Carcharhinus plumbeus

  • Matias Braccini (Department of Primary Industries and Regional Development, Western Australia)
  • Ian Jacobsen (Department of Agriculture and Fisheries, Queensland)
  • Michael Usher (Department of Industry, Tourism and Trade, Northern Territory)
  • Victor Peddemors (New South Wales Department of Primary Industries)

Date Published: June 2023

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Summary

Sandbar Shark occurs primarily off both the east and west coasts of Australia. The eastern Australian stock is sustainable and the Western Australian stock is recovering.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Stock status Indicators
Northern Territory Western Australia Recovering Catch, CPUE , fishing mortality
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Stock Structure

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 [McAuley et al. 2007a; Last and Stevens 2009]. 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. Conventional tagging data and recent genomic studies indicate that Sandbar Sharks form a single population within Western Australia (McAuley et al. 2005; Pember et al 2023). 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.

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Stock Status

Western Australia

In Western Australia, Sandbar Shark is targeted by the West Coast Demersal Gillnet and Demersal Longline Fishery, and is also taken in lesser quantities by the Joint Authority Southern Demersal Gillnet and Demersal Longline Managed Fishery [McAuley et al. 2015]. Sandbar Shark 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 are recently quantified catches from the Memorandum of Understanding (MoU) Box Shark Fishery [Marshall et al. 2016, Braccini et al. 2021].

The status of this stock was initially assessed using demographic modelling techniques and fishing mortality rates estimated from tagging studies between 2001 and 2004 [McAuley et al. 2005; McAuley et al. 2007b]. This assessment  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 reported catches peaked at 918 t) and had probably exceeded sustainable levels since 1997–98. These conclusions were supported by fishery-independent survey data that indicated declining breeding stock abundance between 2002 and 2005 [McAuley et al. 2005; McAuley and Rowland 2012].

Since 2010, Sandbar Shark catches have remained well below the levels expected to allow a gradual recovery of the breeding stock [McAuley et al. 2015]. The expected reductions in recruitment from historical excessive exploitation of the breeding stock are likely to have been ameliorated by this significant reduction in targeted fishing effort. Therefore, the more recent levels of fishing were considered suitably precautionary to ensure the recovery of this biological stock [McAuley et al. 2015].

In 2018, a stock assessment was conducted based on a risk-based weight of evidence approach using all available lines of evidence, including simulated biomass trajectories derived from a combination of demographic modelling and catch-only modelling [Braccini et al. 2018]. This assessment estimated a “Medium” current sustainability risk from fishing for the Sandbar Shark stock [Braccini et al. 2018].

Updated stock assessments using a range of catch-only methods, a state-space biomass dynamics model (JABBA, Winker et al. 2018), integrated age-structured models (Stock Synthesis, Methot and Wetzel, 2013), and time series of reconstructed catches, catch rates, abundance and length composition are underway (Braccini et al. unpublished). Preliminary findings, based on catch only methods and the biomass dynamics model, indicate that for the last 10 years total catches have been below those required to achieve MSY and that the recent biomass trajectory has considerably increased. In addition, fishery independent surveys of the adult component of the stock in northern western Australia show a strong increasing trend since 2008.

The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to be impaired. However, for the period 2015 to 2022 these indicators suggest a recovering stock. The above evidence indicates that 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.

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Biology

Sandbar Shark biology [McAuley et al. 2006; McAuley et al. 2007a; Geraghty et al. 2013 ]

Biology
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
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Distributions

Distribution of reported commercial catch of Sandbar Shark

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Tables

Fishing methods
Northern Territory
Commercial
Unspecified
Charter
Hook and Line
Recreational
Hook and Line
Management methods
Method Northern Territory
Commercial
Gear restrictions
Processing restrictions
Quota
Spatial closures
Vessel restrictions
Recreational
Gear restrictions
Possession limit
Catch
Northern Territory
Commercial 96.00kg
Charter Unknown but likely to be negligible
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 – Commercial QLD commercial and charter data has been sourced from the commercial fisheries logbook program.  Further information available through the Fisheries Summary Report (https://www.daf.qld.gov.au/business-priorities/fisheries/monitoring-research/data/queensland-fisheries-summary-report)  

Queensland – Indigenous (management methods) for more information see https://www.daf.qld.gov.au/business-priorities/fisheries/traditional-fishing

New South Wales – Indigenous (Management Methods) https://www.dpi.nsw.gov.au/fishing/aboriginal-fishing

Recreational and Indigenous (catch) Given the offshore distribution of Sandbar Shark, near-shore catches are likely to be negligible.

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Catch Chart

Commercial catch of Sandbar Shark - note confidential catch not shown

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References

  1. Blower D.C., C. Riginos, J.R. Ovenden. (2019). NeOGen: A tool to predict genetic effective population size (Ne) for species with generational overlap and to assist empirical Ne study design. Molecular Ecology Resources 19: 290-271.
  2. Blower, D. C. 2020. Estimating contemporary abundance, demography, and vulnerability to change for long-lived species with effective population size and population simulation. PhD thesis. School of Biological Sciences, p. 257. The University of Queensland.
  3. Braccini, M, Blay, N, Hesp, A, and Molony, B 2018. Resource Assessment Report Temperate Demersal Elasmobranch Resource of Western Australia. Department of Primary Industries and Regional Development. Fisheries Research Report No. 294 Department of Primary Industries and Regional Development, Western Australia. 149 pp
  4. 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.
  5. JABBA: Just Another Bayesian Biomass Assessment. Fish. Res. 204, 275–288
  6. Last, PR and Stevens, JD 2009, Sharks and rays of Australia, 2nd edn, CSIRO Publishing, Collingwood.
  7. 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. Fisheries Management and Ecology, 25: 186–202.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. Peddemors, V, Macbeth, W, Collins, D, Goulstone, A, Ives, M., Ovenden, J., Butcher, P. 2020. Shark Futures: Sustainable management of the NSW whaler shark fishery. Port Stephens, NSW. 190pp.
  17. Population genomic and size distribution data suggest high genetic connectivity in the sandbar shark (Carcharhinus plumbeus) along a 2700 km coastline. Fisheries Research 266: 106779
  18. 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.
  19. Quantifying the unreported and unaccounted domestic and foreign commercial catch of sharks and rays in Western Australia. Ambio 50: 1337-1350
  20. Queensland Government, 2023, Shark Control Program: Shark Catch Statistics by Year. Available at: https://www.data.qld.gov.au/dataset/shark-control-program-shark-catch-statistics (Accessed: 2 August 2023).
  21. Rowling, KA, Hegarty, A and Ives, M 2010, Status of fisheries resources in NSW 2008/09, Industry and Investment New South Wales, Cronulla.
  22. Ryan, K.L., Hall, N. G., Lai, E. K., Smallwood, C. B., Tate, A., Taylor, S. M. and Wise, B. S. (2019). Statewide survey of boat-based recreational fishing in Western Australia 2017/18. Fisheries Research Report No. 297, Department of Primary Industries and Regional Development, Western Australia
  23. Stock synthesis: A biological and statistical framework for fish stock assessment and fishery management. Fish. Res. 142, 86–99
  24. Teixeira, D, Janes, R, and Webley, J 2021, 2019–20 Statewide Recreational Fishing Survey Key Results. Project Report. State of Queensland, Brisbane.

Downloadable reports

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