Giant Crab (2020)
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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.
Stock Status Overview
|Tasmania||Giant Crab Fishery (Tasmania)||Depleted||
CPUE, catch, effort, pre-recruit abundance
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 level—Western Australia and South Australia; and the management unit level—Giant Crab Fishery (Victoria) and Giant Crab Fishery (Tasmania).
Giant Crab Fishery (Tasmania)
A length-based model has been developed to estimate annual levels of Giant Crab biomass and egg production. The model includes catch and effort data from commercial fisheries [Gardner et. al. 2007]. This model was used to develop the current sex-specific size limits (carapace length of 140 mm for males and 150 mm for females to afford protection to mature female crabs, which are also protected whilst berried and through female spawning closures. Despite these measures, egg production has decreased to an estimated 14 per cent of unfished levels in 2013–14 [Emery et. al. 2018]. This level of egg production is considered inadequate relative to benchmarks in most crustacean fisheries [Fogarty and Gendron 2004]. Due to its slow growth and longevity, Giant Crab is particularly susceptible to becoming recruitment overfished.
Since the 2013–14 assessment the model has not been updated due to a lack of data, and analyses have focused instead on CPUE trends. Standardised CPUE decreased by approximately 65% from the inception of the Tasmanian fishery to 2015. Since 2015 standardised CPUE appears to have stabilised with an early indication of a possible increase, however at present this is insufficient evidence to indicate that the stock is recovering. The above evidence indicates that the biomass of this stock is likely to be depleted and that recruitment is likely to be impaired. The above evidence also indicates the current fishing mortality levels are expected to prevent the stock recovering from a recruitment impaired state.
On the basis of the evidence presented above, the Giant Crab Fishery (Tasmania) management unit is classified as a depleted stock.
Giant Crab biology [Gardner 1998, McGarvey et. al. 1999, Williams et. al. 2009,]
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|Giant Crab||≥ 30 years, > 200 mm CL , ~10 kg||125–140 mm CL, depending on region|
|Pots and Traps|
|Giant Crab Trap|
|Giant Crab Trap|
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.
- Emery, T, Hartmann K and Gardner C, 2015, Giant Crab stock assessment report 2013/14, IMAS, Hobart.
- Fisheries Victoria 2010, Giant Crab Management Plan, Second Edition, ISBN 978-1-74264-478-3.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- PIRSA 2018, Management Policy for Commercial Fishing of Giant Crabs in South Australia. Primary Industries and Regions South Australia. Adelaide, Australia.
- VFA (2020) 2018/19 Victorian Giant Crab Stock Assessment. Victorian Fisheries Authority Report Series No.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.