The SBPMF operates in the same area as four other major fisheries: the Shark Bay Scallop Managed Fishery (SBSMF), the Shark Bay Crab (Interim) Managed Fishery (SBCIMF), the Gascoyne Demersal Scalefish Managed Fishery (GDSF) and the Inner Shark Bay Scalefish Fishery, which includes the activities of the Shark Bay Beach Seine and Mesh Net Managed Fishery (SBBSMNMF) and the inner Shark Bay recreational fishery.
5.3.1 Shark Bay Scallop Managed Fishery
The scallop resource in Shark Bay is fished by both the SBPMF and the SBSMF, with large areas of spatial overlap. The inter-relationship between trawling activities for the prawns and scallops has raised both management challenges and industry conflicts over time, and has also been the focus of an FRDC funded research project (Kangas et al. 2012). A comprehensive review of the fisheries was undertaken (Department of Fisheries [DoF] 2010) to address issues such as resource sharing and gear interaction issues between the scallop and prawn fleets and continued variations in scallop stock levels in Shark Bay.
As scallops have historically been an important component of the viability of the prawn fleet, the Minister for Fisheries adopted a formal catch share management objective for the annual scallop catch between A Class (scallop only) and B Class (prawn and scallop) boats of 70 % and 30 %, respectively (Sporer et al. 2013).
Due to the low catch predictions for scallops based on annual recruitment surveys, the SBSMF was closed in 2012 and 2013. A small area where some recruit scallops were identified in Denham Sound was closed to prawn trawling in 2013 as an additional protective measure for the scallop spawning stock (Sporer et al. 2013). Subsequent surveys have indicated that some recovery of the scallop stock is evident (DoF unpublished data).
5.3.2 Shark Bay Crab (Interim) Managed Fishery
The blue swimmer crab resource in Shark Bay is harvested commercially by the SBCIMF and the SBPMF, with small amounts also retained by the SBSMF. There are currently five 300-trap licences and 28 trawl licences (18 prawn and 10 scallop) authorised to take blue swimmer crabs in Shark Bay.
While blue swimmer crabs have been retained by the SBPMF since its inception, the prawn trawl licensees have steadily increased their capacity to process and retain crabs since 2000.
Consequently, the trawl crab catch rose steadily from 43 t in 2000 (15 % of the total blue swimmer crab catch in Shark Bay) to 338 t in 2010 (41 % of the total blue swimmer crab catch in Shark Bay), with crabs now forming an important economic component of the trawl catch (Harris et al. 2012).
Since 2011, catches of blue swimmer crabs in Shark Bay have declined sharply for both the trap and trawl sectors, suggesting a significant depletion of large (≥ 135 mm carapace width [CW]) crabs. The mean monthly trap catch rate fell from 2.2 kg / traplift in June 2011, to 1.7 kg / traplift in August 2011, to less than 1 kg / traplift by October 2011. Similarly, the total monthly retained trawl catch declined from over 90 t in April 2011, to around 30 t by July 2011, with just two tonnes taken in September 2011. A significant reduction was also recorded in the abundance of recruits (< 85 mm CW) in the fishery. The reasons for this unexpected and substantial decline are yet to be clearly understood, but it is possibly linked to several adverse extreme environmental events that occurred during the summer of 2010/11 associated with a very strong La Niña event (Harris et al. 2012).
Due to this decline, commercial fishing for blue swimmer crabs in Shark Bay was voluntarily halted by industry in April 2012, continuing until October 2013 (Chandrapavan et al. 2013).
During this time, there was no retention of blue swimmer crabs in Shark Bay.
Since the voluntary closure of the Shark Bay crab fishery in 2012, intensive monitoring of the resource and its recovery has been undertaken using a combination of trawl (FRDC project) and trap-based (funded by the Department) surveys (Chandrapavan et al. 2014). These surveys were designed to target key deep-water trawl grounds and inshore trapping grounds that have historically been used to target crabs. New survey sites have also been added to explore non-traditional crab regions to further understand stock distribution and movement at the lower abundances that currently exist.
In June 2013, an exemption was granted for a commercial crab fishing trial as a result of some improvement in the crab biomass indices from both of these surveys (Chandrapavan et al. 2014). A nominal ‘quota’ of 18 t was set for a single trap fisher for this fishing period (max. 400 traps) and was monitored on a daily basis. The trawl sector was also set a collective quota of 18 t, allowing for 1 t per fishing boat. The total trap catch was 20 t (slightly above the 18 t limit due to the addition of fishing days for inclusion of a commercial monitoring survey over 1 – 5 July). The total trawl crab catch was 16 t (Chandrapavan et al.
2014).
Based on the results of the commercial fishing trial and improving crab stock status as indicated by fishery-independent surveys, the resumption of limited commercial crab fishing was approved by the Department in 2013. A precautionary total allowable commercial catch (TACC) of 400 t was set for the 2013/14 season (Chandrapavan et al. in press). The 400 t approval provides for the harvest of up to 264 t of crabs by the trap sector and the harvest of up to 135.2 t by the prawn trawl sector. The Shark Bay blue swimmer crab stock continues to recover from environmental impacts on recruitment as indicated by the significantly high biomass levels in 2014 (DoF unpublished data; see also Section 10.1.1.3).
In order to facilitate stock rebuilding, the Department has been working on the development of an effective harvest strategy for the blue swimmer crab stock in Shark Bay, along with management arrangements to provide for the sharing of the fishery between trap and trawl sectors. In June 2013, the then Minister for Fisheries approved the development of a Shark Bay Crab Managed Fishery Management Plan, which will incorporate the prawn trawl, scallop trawl and trap sectors and be based on an Individual Transferable Quota (ITQ) system of entitlement. It was determined that the commercial blue swimmer crab resource in Shark Bay would be allocated across the prawn trawl, scallop trawl and trap sectors based upon the proportional catch history of each sector between 2007 and 2011, resulting in the following allocations:
• Trap sector: 66.0 %;
• Prawn trawl sector: 33.8 %; and
• Scallop trawl sector: 0.02 %.
The new management plan is expected to be completed in mid-2015.
5.3.3 Gascoyne Demersal Scalefish Managed Fishery
The GDSF encompasses commercial and recreational fishing for demersal scalefish in continental shelf waters of the Gascoyne Coast Bioregion. At Shark Bay, fishers primarily target the oceanic stock of pink snapper (Pagrus auratus) although several other demersal species are also retained. A limited number of licenced charter vessels and a large number of recreational vessels fish out of Denham, Carnarvon and around the Ningaloo area (i.e. Coral Bay, Tantabiddi and Exmouth) and catch a similar range of demersal species (Jackson et al.
2013a).
In 2013, the commercial GDSF retained 389 t of demersal scalefish, including 235 t of pink snapper (Jackson et al. 2013a).
5.3.4 Inner Shark Bay Scalefish Fishery
The Inner Shark Bay Scalefish Fishery encompasses the SBBSMNMF and the inner Shark Bay recreational fishery for scalefish species within the waters of the Eastern Gulf, Denham Sound and Freycinet Estuary in Inner Shark Bay. The SBBSMNMF operate from Denham and uses a combination of beach seine and mesh nets to target four main species / groups:
whiting (Sillago spp.), sea mullet (Mugil cephalus), tailor (Pomatomus saltatrix) and western yellowfin bream (Acanthopagrus morrisoni; Jackson et al. 2013b).
5.3.5 Recreational Fishing
Recreational fishing effort (for all species) in the Gascoyne Coast Bioregion during 2011/12 was estimated as 13 % of the entire State recreational fishing effort. Most recreational fishing in Shark Bay is boat-based, with fishers using rod and line or handlines to target demersal finfish species such as pink snapper (P. auratus) (Jackson et al. 2013b). Some netting for bait and sea mullet also occurs in the area.
Recreational fishing activity for prawns in Shark Bay is considered negligible. There is a state-wide recreational daily bag limit of nine litres of prawns. Prawns can be legally caught using a single hand-dip net, hand scoop net, hand throw net or prawn hand trawl (drag) net that is not more than four metres across with a mesh of not less than 16 mm, and must not be attached to a boat or set. A net fishing licence is required if using set, haul or throw nets. A recreational boat fishing licence is required if catching prawns from a powered boat.