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Giant Crab (2023)

Pseudocarcinus gigas

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

Date Published: June 2023

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Summary

Giant Crab occurs from WA to TAS with weakly connected stocks throughout this range. The stock associated with each cluster of fishing is assessed here. The Western Australian and South Australian stocks are sustainble. The stock West of Bass Strait is recovering. The stock East of Tasmania is undefined due to limited fishing and data.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Stock status Indicators
South Australia South Australia Depleting

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

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Stock Structure

Giant Crab is continuously distributed across its range from Western Australia to East of Tasmania. Movement of giant crab post-settlement is limited. 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 reasonably large spatial scales [Gardner 1998; Gardner and Quintana 1998; Williams et. al. 2009]. However, given the large spatial scale of the distribution and features that disrupt dispersal (such as the Bass Strait) the species is likely to consist of a series of local populations with moderate connectivity within the meta population. An FRDC project is currently underway which will provide further clarification on stock structure for future assessments (FRDC Project 2021-025 Resolving the biological stock structure of Southern Ocean crab fisheries).

Fishing occurs in four spatial clusters which are sufficiently separated that each cluster is likely to be fishing a local stock that has a low level of connectivity with the other stocks. The stock "West of Bass Strait" is fished by both Victoria and Tasmania. This stock previously had differing assessments for the two jurisdictions which resulted in an assessment on a jurisdictional basis. However, these differences have now been resolved. Consequently, assessment of stock status is presented here at the biological-stock level—Eastern Tasmania, South Australia, West of Bass Strait, and Western Australia.

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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 2023].

The most recent assessment was based on data to the end of the 2022–23 season (1 October 2022–31 May 2023) [SARDI unpublished data]. In 2022–23, 7,604 potlifts caught a total of 13.3 t of Giant Crab, comprising 60.2 per cent of the TACC of 22.1 t in that season.

Commercial CPUE increased from 2.32 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 2.25 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 2014–15, CPUE levels have declined, but remained above the trigger level of 1.95 kg/potlift and at approximately 82 per cent of the target level until 2021–22 [McLeay 2023]. In 2022–23, commercial CPUE declined further to below the trigger level and was 1.88 kg/potlift. The above evidence indicates that the biomass of this stock is not yet depleted, and recruitment is not yet impaired but fishing mortality is too high and moving the stock in the direction of becoming recruitment impaired. On the basis of the evidence presented above, Giant Crab in South Australia is classified as a depleting 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

at least 30 years, greater than 200 mm CL , approximately 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 10.33t
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 2021–22 fishing season (November 2021–September 2022), Tasmanian data are for the 2022-23 fishing season (March 2022 – February 2023) 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 fishinglicence 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 2023, Stock status report for the South Australian South Australian Giant Crab (Pseudocarcinus gigas) Fishery in 2021/22. Fishery Status Report to PIRSA Fisheries and Aquaculture. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2011/000332-12. SARDI Research Report Series No. 1173.
  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.