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Giant Crab (2020)

Pseudocarcinus gigas

  • Klass Hartmann (Institute of Maine and Antarctic Studies, University of Tasmania)
  • David Reilly (Victorian Fisheries Authority)
  • Jason How (Department of Primary Industries and Regional Development, Western Australia)
  • Lachlan McLeay (South Australian Research and Development Institute)

Date Published: June 2021

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Summary

Giant Crab occurs from WA to TAS but it is considered a single biological stock. Nevertheless, stocks are classified separately for the four states. Stock is sustainable in WA, SA and VIC, and depleted in TAS.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Stock status Indicators
South Australia South Australia Sustainable

CPUE, catch, effort, mean weight, pre-recruit abundance, sex ratio, spawning female abundance

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Stock Structure

Giant Crab is considered to be a single biological stock from Western Australia to Tasmania because the species is continuously distributed across this range. Planktonic larval duration is around 50 days, with larval release occurring along the edge of the continental shelf. The shelf is a high current area, facilitating dispersal, and oceanographic modelling has indicated that Giant Crab dispersal occurs over large spatial scales [Gardner 1998, Gardner and Quintana 1998, Williams et. al. 2009].

Status of Australian Fish Stocks reports on Giant Crab up to 2016 provided an overall assessment for this assumed biological stock. However, there have been significant changes in the relative performance of the various fisheries operating across this stock since 2014. New information indicates that Giant Crab are now considered to be depleted in Tasmania but sustainable in Western Australia. It is difficult to reconcile these differences in regional depletion levels under an assumption of a single stock. But management arrangements also vary across jurisdictions and the fishing fleets in each jurisdiction consist of vessels with different characteristics, resulting in different patterns of exploitation.

Assessment of stock status is presented here at the jurisdictional levelWestern Australia and South Australia; and the management unit levelGiant Crab Fishery (Victoria) and Giant Crab Fishery (Tasmania).

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Stock Status

South Australia

The South Australian Giant Crab Fishery comprises three commercial fishing sectors: (1) the Miscellaneous Fishery sector; (2) the South Australian Rock Lobster Fishery (SARLF) quota sector (RL-quota); and (3) the SARLF by-product sector (RL by-product). Fishing mortality in South Australia is managed through Total Allowable Commercial Catches (TACCs) and a minimum legal size (MLS) (150 mm carapace length) to protect females up to spawning size. The management policy for the fishery guides the classification of stock status relative to limit, trigger and target reference points for a CPUE-based performance indicator relating to relative stock biomass measured from 2000–01 to 2009–10 (a relatively stable period of data collection from Giant Crab catch logbooks). The five-year average commercial CPUE of legal-size Giant Crab calculated from data collected from targeted fishing in the Miscellaneous Fishery and RL-quota sectors is the primary indicator for biomass and fishing mortality [PIRSA 2018, McLeay 2020].

The most recent assessment was based on data to the end of the 2018–2019 season (1 October 2018–31 May 2019) [McLeay 2020]. In 2018–19, 8 051 potlifts caught a total of 16.8 t of Giant Crab, comprising 76.0 per cent of the TACC of 22.1 t in that season.

Commercial CPUE increased from 2.3 kg/potlift at the start of the time series in 2004–05 to reach a peak of 3.05 kg/potlift in 2008–09. CPUE then decreased to 2.3 kg/potlift in 2013–14. Average CPUE over the period 2004–13 was 2.62 kg/potlift, and above the target of 2.60 kg/potlift. Since then, CPUE levels have been lower than historical values but relatively stable, remaining above the trigger level of 1.95 kg/potlift and at approximately 83 per cent of both the 2004–13 average and the target level [McLeay 2020]. In 2018–19 commercial CPUE was 2.13 kg/potlift.  The above evidence indicates that the biomass of this stock is unlikely to be depleted and that recruitment is unlikely to be impaired. Furthermore, the evidence indicates that the current level of fishing mortality is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence presented above, Giant Crab in South Australia is classified as a sustainable stock.

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Biology

Giant Crab biology [Gardner 1998, McGarvey et. al. 1999, Williams et. al. 2009,]

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Giant Crab ≥ 30 years, > 200 mm CL , ~10 kg 125–140 mm CL, depending on region
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Distributions

Distribution of reported commercial catch of Giant Crab
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Tables

Fishing methods
South Australia
Commercial
Giant Crab Trap
Indigenous
Giant Crab Trap
Recreational
Giant Crab Trap
Management methods
Method South Australia
Commercial
Limited entry
Quota
Size limit
Spatial closures
Temporal closures
Indigenous
Size limit
Temporal closures
Recreational
Size limit
Temporal closures
Catch
South Australia
Commercial 16.80t
Indigenous Negligible
Recreational Negligible

South Australian data are from quota holders in the 2016–17 fishing season (October 2016–May 2017), Victorian data are for the 2016–17 fishing season (November 2016–September 2017), Tasmanian data are for the 2017-18 fishing season (March 2017 – February 2018) and South Coast  Crustacean Managed Fishery (Western Australia) data are for the 2019–20 financial year. 

 

Victoria – Indigenous (Management Methods) A person who identifies as Aboriginal or Torres Strait Islander is exempt from the need to obtain a Victorian recreational fishing licence, provided they comply with all other rules that apply to recreational fishers, including rules on equipment, catch limits, size limits and restricted areas. Traditional (non-commercial) fishing activities that are carried out by members of a traditional owner group entity under an agreement pursuant to Victoria’s Traditional Owner Settlement Act 2010 are also exempt from the need to hold a recreational fishing licence, subject to any conditions outlined in the agreement. Native title holders are also exempt from the need to obtain a recreational fishing licence under the provisions of the Commonwealth’s Native Title Act 1993.

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Catch Chart

Commercial catch of Giant Crab - note confidential catch not shown
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References

  1. Emery, T, Hartmann K and Gardner C, 2015, Giant Crab stock assessment report 2013/14, IMAS, Hobart.
  2. Fisheries Victoria 2010, Giant Crab Management Plan, Second Edition, ISBN 978-1-74264-478-3.
  3. Fogarty, MJ and Gendron, L 2004, Biological reference points for American lobster (Homarus americanus) populations: limits to exploitation and the precautionary approach, Canadian Journal of Fisheries and Aquatic Sciences, 61(8): 1392–1403.
  4. Gardner, C 1998, First record of larvae of the Giant Crab Pseudocarcinus gigas in the plankton, Papers and Proceedings of the Royal Society of Tasmania, 132: 47–48.
  5. Gardner, C and Quintana R 1998, Larval development of the Australian Giant Crab Pseudocarcinus gigas (Lamarck, 1818) (Decapoda: Oziidae) reared in the laboratory, Journal of Plankton Research, 20(6): 1169–1188.
  6. Gardner, C, Haddon, M, Hobday,D and McGarvey R 2007, Development of the tools for long term management of the Giant Crab resource: data collection methodology, stock assessment and harvest strategy evaluation, final report to the Fisheries Research and Development Corporation, Canberra.
  7. McGarvey, R, Matthews, JM and Levings, AH 1999, Yield-, value-, and egg-per-recruit of Giant Crab, Pseudocarcinus gigas, South Australian Research and Development Institute, Adelaide.
  8. McLeay, L, 2020, Stock status report for the South Australian South Australian Giant Crab (Pseudocarcinus gigas) Fishery in 2018/19. Fishery Status Report to PIRSA Fisheries and Aquaculture. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2011/000332-9. SARDI Research Report Series No. 1050.
  9. PIRSA 2018, Management Policy for Commercial Fishing of Giant Crabs in South Australia. Primary Industries and Regions South Australia. Adelaide, Australia.
  10. VFA (2020) 2018/19 Victorian Giant Crab Stock Assessment. Victorian Fisheries Authority Report Series No.11
  11. Williams, A, Gardner, C, Althaus, F, Barker, B and Mills D 2009, Understanding shelf-break habitat for sustainable management of fisheries with spatial overlap, final report to the Fisheries Research and Development Corporation, project 2004/066, CSIRO Marine and Atmospheric Research, Hobart.

Downloadable reports

Click the links below to view reports from other years for this fish.