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Blue Swimmer Crab (2018)

Portunus armatus

  • Danielle Johnston (Department of Primary Industries and Regional Development, Western Australia)
  • Arani Chandrapavan (Department of Primary Industries and Regional Development, Western Australia)
  • Anna Garland (Department of Agriculture and Fisheries, Queensland)
  • Crystal Beckmann (South Australian Research and Development Institute)
  • Daniel Johnson (Department of Primary Industries, New South Wales)

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Summary

Australia has ten stocks of Blue Swimmer Crab across WA, Qld, NSW and SA. Eight of those stocks are sustainable with two stocks in WA classified as recovering.

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Stock Status Overview

Stock status determination
Jurisdiction Stock Fisheries Stock status Indicators
New South Wales South Eastern Australia EGF, EPTF, OTF Sustainable Catch, effort, CPUE, size composition
EGF
Estuary General Fishery (NSW)
EPTF
Estuary Prawn Trawl Fishery (NSW)
OTF
Ocean Trawl Fishery (NSW)
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Stock Structure

Blue Swimmer Crab is distributed in Australia from the south coast of Western Australia, north to the Northern Territory, across Queensland, down the east coast and to the New South Wales–Victoria border. They are also found in the warmer waters of the South Australian gulfs [Kailola et al. 1983].

In Western Australia, Blue Swimmer Crab is fished in numerous fisheries across five regions. The stock delineation between these regions is unknown [Chaplin et al. 2001; Chaplin et al. 2008]. Stock structure on the east coast of Australia is uncertain, involving overlapping stocks or a semi-continuous stock [Chaplin et al. 2001]. Due to the geographic separation between the major fishing grounds for Blue Swimmer Crab in New South Wales and Queensland, they are managed as two separate biological stocks. In South Australia, research has identified three separate biological stocks of Blue Swimmer Crab—in Spencer Gulf, Gulf St Vincent and on the coastline west of the Eyre Peninsula [Bryars and Adams 1999, Dixon and Hooper 2011].

Here, assessment of stock status is presented at the biological stock level—North-Eastern Australia (Queensland), South-Eastern Australia (New South Wales), Spencer Gulf, Gulf St Vincent and West coast (South Australia), and at the management unit level—Shark Bay, Cockburn Sound, Peel-Harvey Estuary, Western Australian North Coast and Western Australian South-West Coast (Western Australia).

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Stock Status

South Eastern Australia

Blue Swimmer Crabs occur in coastal and estuarine waters along the length of the New South Wales coastline. New South Wales Blue Swimmer Crab populations are at the southern end of the species distribution along the east coast and have a limited spawning period (November–February), rather than the year-round spawning that occurs in more northern latitudes [Johnson et al. 2010]. A legal minimum size (LMS) of 60 and 65 mm carapace length is enforced for recreational and commercial fishers, respectively. Female crabs close to the LMS are sexually mature, and are capable of producing one–three batches of eggs within a season [Johnson et al. 2010].

The most recent estimate of the recreational harvest of Blue Swimmer Crabs in New South Wales was approximately 51 000 crabs (27 t) during 2013–14 [West et al. 2016]. The annual recreational harvest of Blue Swimmer Crabs in New South Wales was previously estimated to lie between 150 and 310 t based on the results of the National Recreational and Indigenous Fishing Survey [Henry and Lyle 2003] and surveys undertaken by New South Wales Department of Primary Industries. Commercial catches of this species have tended to fluctuate around a long-term average of about 144 t over the period 2000/01–2016/17. Nominal catch rates of Blue Swimmer Crabs by the main fishing methods in the Estuary General Fishery (EGF) have remained relatively steady and have been above long-term averages for the past five years. Four estuaries account for 85 per cent of commercial Blue Swimmer Crab landings in New South Wales (121 t in 2016/17), the most important being Wallis Lake (99 t in 2016/17). Catch rates in Wallis Lake appear stable and within historic levels indicating a stable level of biomass in this area. Since the transition to daily reporting in 2009/10, annual commercial catch rates (kg.day-1) for fish trapping, the method that accounts for around 95 per cent of commercial landings (95 t in 2016/17) have fluctuated between 14.1 and 35.3 kg.day-1, but have generally remained above the eight year mean catch rate of 25 kg.day-1. In 2016/17, total landings from Wallis Lake (99 t) and CPUE(30.1 kg.day-1) were six and 24 per cent higher than eight year averages, respectively. The length compositions of the commercial landings for this species have been stable since monitoring commenced in 2009 [Stewart et al. 2015]. Nominal effort levels (in the number of fisher days) over the past eight years have remained steady (~2900 per year), and are well below historical levels (> 8 000 per year).

Fishing mortality in the EGF is now controlled through an interim Total Commercial Access Level (ITCAL) of 223 t, with catch allocations based on current shareholdings, effective from 1 December 2017. The increased minimum legal length for the commercial sector and, the implementation of daily possession limit for all ocean fisheries (25 kg) has reduced fishing pressure on the spawning stock. This reduction in fishing effort in combination with stable size compositions in landings indicates that fishing mortality is constrained in New South Wales waters to sustainable levels.

The above evidence indicates that the biomass of this stock is unlikely to be depleted and the current level of fishing mortality in New South Wales is unlikely to cause the stock to become recruitment impaired.

On the basis of the evidence provided above, the South-Eastern Australia (New South Wales) biological stock is classified as a sustainable stock.

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Biology

Blue Swimmer Crab Biology [de Lestang et al. 2003a,b, Sumpton et al. 2003]

Biology
Species Longevity / Maximum Size Maturity (50 per cent)
Blue Swimmer Crab 3–4 years, ~ 200 mm CW Varies among locations, 6–14 months, 86–110 mm CW 
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Distributions

Blue Swimmer Crab Spatial Distribution

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Tables

Fishing methods
New South Wales
Commercial
Mesh Net
Otter Trawl
Unspecified
Crab Trap
Fish Trap
Recreational
Dip Net
Blue Swimmer Crab Trap
Management methods
Method New South Wales
Commercial
Gear restrictions
Limited entry
Protection of egg-bearing females
Size limit
Spatial closures
Spatial zoning
Total allowable catch
Vessel restrictions
Indigenous
Native Title
Section 37 (1d)(3)(9), Aboriginal cultural fishing authority
Recreational
Gear restrictions
General recreational licence or fishing boat licence (not species specific)
Protection of egg-bearing females
Size limit
Spatial closures
Active vessels
New South Wales
169 in EGF, 18 in EPTF, 56 in OTF
EGF
Estuary General Fishery (NSW)
EPTF
Estuary Prawn Trawl Fishery (NSW)
OTF
Ocean Trawl Fishery (NSW)
Catch
New South Wales
Commercial 131.20t in EGF, 1.54t in EPTF, 3.00t in OTF
Indigenous Unknown
Recreational 27 t (2013–14)
EGF
Estuary General Fishery (NSW)
EPTF
Estuary Prawn Trawl Fishery (NSW)
OTF
Ocean Trawl Fishery (NSW)

Western Australia – Recreational (catch) Boat-based recreational catch from 1 May 2013–30 April 2014 [Ryan et al. 2018].

Queensland – Indigenous (Management Methods) Under the Fisheries Act 1994 (Qld), Indigenous fishers in Queensland are entitled 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 37d) (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.

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Catch Chart

Commercial catch of Blue Swimmer Crab - note confidential catch not shown.

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References

  1. Beckmann, CL and Hooper, GE 2018, Blue Crab (Portunus armatus) Fishery 2016/17. Fishery Assessment Report to PIRSA Fisheries and Aquaculture. South Australian Research and Development Institute (Aquatic Sciences), Adelaide. SARDI Publication No. F2007/000729-14. SARDI Research Report Series No. 980. 59pp.
  2. Bryars, S and Adams, M 1999, An allozyme study of the blue swimmer crab, Portunus pelagicus (Crustacea: Portunidae), in Australia: stock delineation in southern Australia and evidence for a cryptic species in northern waters, Marine and Freshwater Research, 50: 15–26.
  3. Chaplin, J, Yap, ES, Sezmis, E and Potter, IC 2001, Genetic (microsatellite) determination of the stock structure of the blue swimmer crab in Australia, Fisheries Research and Development report, FRDC project 98/118, Murdoch University, Western Australia.
  4. Chaplin, JA and Sezmis, E 2008, A genetic assessment of the relationships among the assemblages of the blue swimmer crab, Portunus pelagicus, in Cockburn Sound, the Swan River Estuary and Warnbro Sound, Final report to the Department of Fisheries, Western Australia, Centre for Fish and Fisheries Research, Murdoch University.
  5. de Lestang, S, Bellchambers, LM, Caputi, N, Thomson, AW, Pember, MB, Johnston, DJ and Harris, DC 2010, Stock– recruitment–environment relationship in a Portunus pelagicus fishery in Western Australia, in GH Kruse, GL Eckert, RJ Foy, RN Lipcius, B Sainte-Marie, DL Stram and D Woodby (eds), Biology and management of exploited crab populations under climate change, Alaska Sea Grant, University of Alaska, Fairbanks, doi: 10.4027/bmecpcc.2010.06.
  6. de Lestang, S, Hall, NG and Potter, IC 2003a, Reproductive biology of the Blue Swimmer Crab, Portunus pelagicus (Decapoda: Portunidae) in five water bodies on the west coast of Australia, Fishery Bulletin, 101: 745–757.
  7. de Lestang, S, Hall, NG and Potter, IC 2003b, Do the age compositions and growth of the crab Portunus pelagicus in marine embayments and estuaries differ?, Journal of the Marine Biological Association of the United Kingdom, 83: 1– 8.
  8. Dixon, CD and Hooper, GE 2011, Blue Crab (Portunus pelagicus) Fishery 2009/10, Stock assessment report to Primary Industries and Resources South Australia (Fisheries and Aquaculture), South Australian Research and Development Institute publication F2007/000729-7, SARDI research report series 531, SARDI, Adelaide.
  9. Henry GW, Lyle JM 2003, The national recreational and Indigenous fishing survey. Fisheries Research and Development Corporation, Canberra.
  10. Johnson, DD, Gray, CA and Macbeth, WG 2010, Reproductive biology of Portunus pelagicus in a south-east Australian estuary, Journal of Crustacean Biology, 30: 200–205.
  11. Johnston, D, Chandrapavan, A, Wise, B and Caputi, N 2014, Assessment of blue swimmer crab recruitment and breeding stock levels in the Peel–Harvey Estuary and status of the Mandurah to Bunbury Developing Crab Fishery, Fisheries research report 258, Western Australian Department of Fisheries, Perth.
  12. Johnston, D, Harris, D, Caputi, N, de Lestang, S and Thomson, A 2011b, Status of the Cockburn Sound Crab Fishery, Fisheries research report 219, Western Australian Department of Fisheries, Perth.
  13. Johnston, D., Marks, R. and O’Malley, J. (2018). West Coast Blue Swimmer Crab Fishery Status Report 2017, in Gaughan, D.J. and Santoro, K. (eds), Status reports of the fisheries and aquatic resources of Western Australia 2015/16: the state of the fisheries. Report prepared by the Western Australian Department of Fisheries.
  14. Johnston, DJ, Harris, D, Caputi, N and Thomson, P 2011a, Decline of a blue swimmer crab (Portunus pelagicus) fishery in Western Australia—history, contributing factors and future management strategy, Fisheries Research, 109(1): 119– 130.
  15. Johnston, DJ, Smith, KA, Brown, JI, Travaille, KL, Crowe, F, Oliver, RK and Fisher, EA 2015, Western Australian Marine Stewardship Council Report Series No 3: West Coast Estuarine Managed Fishery (Area 2: Peel-Harvey) and Peel-Harvey Estuary Blue Swimmer Crab Recreational Fishery. Department of Fisheries, Western Australia. 284 pp.
  16. Kailola, PJ, Williams, MJ, Stewart, PC, Reichelt, RE, McNee, A and Grieve, C 1993, Australian fisheries resources, Bureau of Resources and Fisheries Research and Development Corporation, Canberra.
  17. Kumar, MS, Xiao, Y, Venema, S and Hooper, G 2003, Reproductive cycle of the blue swimmer crab, Portunus pelagicus, off southern Australia, Journal of the Marine Biological Association of the United Kingdom, 83: 983–994.
  18. PIRSA 2018, Management Plan for the South Australian Commercial BCF. South Australian Fisheries Management Series Paper No. 75. Adelaide, Australia: Primary Industries and Regions South Australia (Fisheries and Aquaculture).
  19. Queensland Department of Agriculture and Fisheries 2018, Queensland Stock Status Assessment Workshop Proceedings 2018. Species Summaries. 19–20 June 2018, Brisbane.
  20. Ryan, KL, Hall, NG, Lai, EK, Smallwood, CB, Taylor, SM, and Wise, BS 2017, State-wide survey of boat based recreational fishing in Western Australia 2015/16. , Fisheries research report 287, Department of Primary Industries and Regional Development, western Australia, 205pp.
  21. Stewart, J, Hegarty, A, Young, C, Fowler, AM and Craig, J 2015, Status of Fisheries Resources in NSW 2013-14, NSW Department of Primary Industries, Mosman: 391pp.
  22. Sumpton, W, Campbell, M, O’Neill, M, McLennan, M, Campbell A and Leigh, G 2015, Assessment of the blue swimmer crab (Portunus armatus) fishery in Queensland. Department of Agriculture and Fisheries, Brisbane.
  23. Sumpton, W, Gaddes, S, McLennan, M, Campbell, M, Tonks, M, Good, N and Hagedoorn, W 2003, Fisheries biology and assessment of the blue swimmer crab (Portunus pelagicus) in Queensland, Queensland Department of Primary Industries and Fisheries Research and Development Corporation project 98/117.
  24. West, LD, Stark, KE, Murphy, JJ, Lyle, JM and Ochwada-Doyle, FA 2016, Survey of Recreational Fishing in New South Wales and the ACT, 2013/14, NSW Fisheries Final Report Series 149.