Prawn (Gulf St Vincent) Fishery

The three prawn fisheries in South Australia — Spencer Gulf, Gulf St Vincent and the West Coast — are all based exclusively on the western king prawn (Melicertus latisulcatus).

The western king prawn has a wide distribution over the Indo-Pacific region. The world’s largest known population of western king prawns is in Spencer Gulf. South Australia’s prawn fisheries are somewhat unique due to their geographical location, cold-water environments and the existence of only one commercial Penaeid species in the fishery.

Licensed prawn fishers are permitted to take several other species as byproduct, which are not targeted, but caught incidentally during fishing operations. The Spencer Gulf and Gulf St Vincent fisheries are permitted to retain slipper lobster (Ibacus spp) and calamari (Sepioteuthis australis), while the West Coast fishery is permitted to retain these species as well as octopus (Octopus spp), scallop (Family Pectinidae) and arrow squid (Nototodaru gouldi).

Trawling is undertaken at night (from sunset to sunrise) using the demersal otter trawl technique. This consists of towing a funnel shaped net, which leads into a bag (referred to as a cod-end), over the sea bottom. The otter boards are used to keep the trawl nets open whilst being towed.  Fishing is generally undertaken using double-rigged trawl gear, although some smaller vessels in the Gulf St Vincent fishery are still permitted to use triple-rigged gear.

Considerable technological advances have been made in the way the catch is handled. These practices are particularly advanced in the Spencer Gulf fishery, with the use of ‘crab bags’ to exclude mega-fauna bycatch, ‘hoppers’ for efficient sorting of the catch and rapid return of bycatch, ‘graders’ to sort the prawns into marketable size categories, and onboard freezing facilities that enable full processing on-board.

Recreational fishing for western king prawns is negligible, as fishers are permitted only to use hand-held nets in waters greater than 10 m in depth (the same depth limitation that applies to commercial fishers). Whilst prawns exist in low abundance in South Australia’s rivers and estuaries, productive prawn areas are generally in waters deeper than 10 m. There is no recorded indigenous fishing for western king prawns in South Australia.

Regulations governing the management of the South Australian prawn fisheries are established in the Fisheries Management (Prawn Fisheries) Regulations 2006 (external site) and the Fisheries Management (General) Regulations 2007. Limited entry regulations apply to each fishery, restricting the number of licences to 39 in Spencer Gulf, 10 in Gulf St Vincent, and three in the West Coast fishery. 

The fisheries in Spencer Gulf and Gulf St Vincent are generally closed in January and February, and from July to October each year. Fishing periods in other months last a maximum of 18 nights from the last quarter to first quarter of the moon phase. Harvest strategies for each period are determined on the basis of data collected during regular fishery-independent and fishery-dependent surveys.

There are also performance indicators and reference points that form the basis upon which the performance of the fisheries are assessed and decisions are made with regard to fishing strategies.  These indicators are provided in the management plans and assessed in SARDI stock assessment reports.