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Government of Western Australia - Department of Fisheries

Blue swimmer crab management

 

The blue swimmer crab resource is accessed by the commercial and recreational sectors. The Department of Primary Industries and Regional Development manages both together to ensure sustainable fisheries.

WA’s annual blue swimmer crab commercial catch usually exceeds 1,000 tonnes. Hundreds of tonnes are also caught by recreational fishers.

We manage fishing through measures including commercial licences and area and seasonal crabbing closures. A minimum legal size limit ensures crabs can spawn at least once before they can be taken.

South West management

Concern about stocks in Cockburn Sound has resulted in Cockburn Sound being closed to crabbing since 2014.

A 2018 review of the South West Blue Swimmer Crab resource, which extends from Perth to Cape Naturaliste, found measures were not adequately protecting breeding stock across the resource. To address this new measures are being introduced to protect the breeding stock:

 

  • A three month closure to recreational and commercial crabbing will be introduced from 1 September to 30 November each year in all coastal waters, rivers and estuaries from the Swan and Canning Rivers to Minninup Beach (15km south of Bunbury).
  • A new bag limit of five crabs per fisher will be introduced for the Swan and Canning Rivers.
  • Geographe Bay will remain open to recreational blue swimmer crab fishing all year, however, recreational fishers will now only be allowed to take a maximum of five females in their bag limit of 10 crabs.
  • The State Government will start the process to buy back commercial fishing licences from oceanic crab fisheries (Cockburn Sound, Warnbro Sound and the Mandurah to Bunbury Developmental Fishery), followed by closure to commercial fishing in these areas.



During the closed season, it is illegal to fish for or be in possession of blue swimmer crab in the closed waters.

Shark Bay management

The Shark Bay crab stock experienced a significant stock decline in late 2011, following a series of adverse environmental conditions between 2010 and 2011, particularly the extreme 2011 marine heatwave. Fewer young crabs survived to enter the adult stocks after ocean surface temperatures reached 4-5ºC above average.

The fishery was closed for 18 months in 2012 and 2013 to promote stock recovery. Limited commercial fishing resumed under a notional quota management system for the 2013/14 (400 tonne) season. Stock continued to recover and a TACC of 450 tonnes was set for the 2014/15 season. In November 2015, the Shark Bay Crab Managed Fishery Management Plan 2015 (Plan) was implemented to consolidate the management arrangements for the commercial take of crabs by the trawl and trap sectors in Shark Bay under an Individual Transferable Quota system.for the catches of this important resource. The TACC for the fishery was maintained at 450tonnes until the 2017/18 season with a 100 tonne increase to 550 tonnes deemed appropriate in the 2017/18season.

Shark Bay crab stocks are assessed as part of a multi-species fishery-independent surveys conducted in February, June and November each year. The current stock assessment indicates that spawning, recruitment and biomass levels have been increasing steadily under increasing catch levels and favourable environmental conditions.

In 2017 the Shark Bay Crab Working Group was established. The Working Group, which includes DPIRD, commercial and recreational fishing representatives, provides a forum for the discussion of management of the SBCMF, including TACC reviews and the development of a harvest strategy to underpin the ongoing sustainable harvest of crabs in Shark Bay. A draft harvest strategy for this fishery is under development by the working group.

A recent review of the TACC during the 2018/19 season found no major changes in the stock indicators so the TACC was maintained at 550t.

Monitoring, assessment and research

To protect stocks into the future, we monitor the status of blue swimmer crab populations and fishing levels.

We use various methods to monitor crab stocks including trapping and trawling surveys which provide information about the abundance, size and reproductive condition of the animals in each population.

Another method is collecting data about effort and catch rates on board commercial vessels. Research staff measure the retained and non-retained catch. We also make estimates of recreational catch and effort from fishing surveys.

By analysing catches, and comparing this information with knowledge about the blue swimmer crab biology and the size and gender structure of the population being fished, researchers are able to draw conclusions about stock status.

Research is continuing into the relationship between different blue swimmer crab populations. This requires an understanding of growth and movement patterns, and the impact of human activities and environmental factors on breeding and growth.

The most recent information on the performance of the blue swimmer crab fisheries can be found in the annual State of the Fisheries Reports.

 

 

Last modified: 6/09/2019 5:18 PM

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