Shark Bay’s Blue swimmer crab (Portunus armatus) resource is commercially harvested by the Shark Bay crab trap and Shark Bay prawn trawl fisheries, with small catches retained by the Shark Bay scallop fishery.
Prior to 2012, this was Australia’s highest producing blue swimmer crab fishery, but an unprecedented marine heatwave in the second half of 2011, coupled with multiple flooding events during the summer of 2010/11, caused a dramatic drop in stocks.
The commercial industry agreed to a voluntary closure of the Blue swimmer crab fishery in April 2012 to allow stocks to rebuild.
Since the closure, intensive monitoring of the resource and its recovery has been undertaken using a combination of trawl and trap based surveys.
Commercial access to blue swimmer crab stocks in WA is governed by a series of separate management arrangements provided for under the legislative framework of the Fish Resources Management Act 1994.
Individual fisheries are currently managed under an input control system, primarily through the regulation of licence and trap (hourglass) numbers or length of headrope of trawl net.
Supplementary controls cover what species can be retained, associated minimum size limits, gear specifications, and area, seasonal and daily time restrictions. The principal management tool employed to ensure adequate breeding stock involves having minimum size limits well above the size at sexual maturity
There are five crab trap permits with combined total of 1500 units of entitlement (currently valued at 1 trap each) in Shark Bay under the Shark Bay Crab Fishery (Interim) Management Plan 2005 which sets the number of traps that can be fished, fishery specific spatial closures, gear specifications and other controls.
These permits are consolidated onto three active vessels. Two permit holders who have a long standing history of crab fishing south of Cape Peron (south of the existing waters of the Shark Bay Crab Interim Managed Fishery), have a Fishing Boat Licence (FBL) condition that allows them to fish in these waters but with no more than 200 traps.
At no time, however, may they each use more than 300 traps in total across all of the waters of Shark Bay.
There are currently 28 trawl (18 prawn and 10 scallop) licences authorised to take Blue swimmer crabs in Shark Bay. Management controls for the trawl fisheries that retain Blue swimmer crabs in the Gascoyne Coast Bioregion, namely the Shark Bay Prawn Managed Fishery and the Shark Bay Scallop Managed Fishery, are based on
limited entry, seasonal and area closures, and gear controls including bycatch reduction devices.
The Department of Fisheries’ vessel monitoring system (VMS) monitors the activities of all trawlers.
In June 2013, a Ministerial decision defined the allocation of catch shares within the commercial sectors as trap – 66 per cent, prawn trawl 33.8 per cent, scallop trawl sector 0.2%.
The then Minister also approved the development of a managed fishery management plan incorporating an Individual Transferable Quota system of entitlement to apply across all three commercial sectors in Shark Bay.
The trap sector had employed about 15 people as skippers and crew on vessels fishing for Blue swimmer crabs in the Gascoyne Coast Bioregion and an additional 30-35 workers in the post-harvest processing of the crab catch.
The loss of these jobs due to the closure of the Shark Bay crab fishery in 2012-13 had a significant socio-economic impact on the area.