Commercial fishing is undertaken along the entire coastal of South Australia. The coastal and offshore waters provide a wide range of habitats, both sheltered and exposed, supporting a diversity of finfish, crustaceans and molluscs. Freshwater species are caught commercially in the River Murray and its associated lakes.
In 1980-81, South Australia accounted for 12% of the gross commercial value of recorded Australian fishery production. (More recent estimates are not available due to a lack of data from Queensland.) In 1983-84 commercial lands in South Australia were valued at $59 million, a figure approximately equal to the State's total value of milk production or of the grape harvest.
The most valuable commercial species are western king prawns (Penaeus latisulcatus) and rock lobsters (Jasus novaehollandiae), with southern bluefin tuna (Thunnus thynnus maccoyii), black and greenlip abalone (Haliotis rubra and H. Laevigata) and King George whiting (Sillaginodes punctatus) also making significant contributions. In terms of live weight of catch, tuna dominates, and in five seasons from 1979-80 contributed between 60% and 74% of the South Australia finfish.
The most important commercial species are tuna, whiting and shark (Elasmobranchii) which comprise 30% of the value of the South Australian fishery yield. In 1983-84, South Australia accounted for 67% of the total recorded Australian catch of tuna, 29% of whiting and 20% of shark.
Until the 1950s finfish exploitation was mainly of whiting and snapper taken by handlines and set gill-nets, and this activity still persists, although new and increasingly efficient methods have also been introduced. State regulations limit entry into the finfish fishery; there were 695 licence holders in June 1984. There is also considerable recreational line fishing activity from shore, jetty and boat.
Southern bluefin tuna are taken in waters west and south of Eyre Peninsula and Kangaroo Island, and most catches are landed at Port Lincoln or Streaky Bay. Spotting aircraft are used in fishing operation, the main methods of capture being by purse-seine nets or pole fishing with live bait. Tuna are either canned for local consumption or frozen for export, notably to Japan. The major species of whiting taken is King George whiting caught in Investigator Strait, the gulf waters, and bays along the west coast of Eyre Peninsula. Two species of shark - school (Galeorhinus australis) and gummy shark (Mustelus antarcticus) - are taken throughout South Australian waters either by large mesh gill-nets or with longlines. Other species of commercial importance include Australian salmon (Arripis trutta esper), garfish (Hyporhampus melanochir), yellow-eyed mullet (Aldrichetta forsteri), tommy ruff (Arripis georgianus) and snapper (Chrysophrys autatus).
Since 1980, freshwater species have contributed between 5% and 9% of the State's annual catch of finfish by live weight. Some sections of the River Murray have been divided into 'reaches' for commercial fishing purposes and each fisherman is licensed by the Department of Fisheries to fish a separate reach. Bony bream (Fluvialosa richardsoni) and European carp (Cyprinus carpio) dominate the freshwater catches, most of which are taken in the lakes, although callop (Plectroplites ambiguus) are significant in the river itself. The largest inland fish, the Murray cod (Maccullochella peeli), are of minor commercial importance.
The South Australian prawn fishery is based on a single species of penaeid prawn, the western king prawn. Prawns accounted for 30% of the value of the State's fishery production in 1983-84; most of the catch is exported. Successful experimental trawling in Spencer Gulf and Gulf St Vincent in 1967 encouraged the conversion of tuna vessels for prawn trawling and today Spencer Gulf is the world's largest producer of western king prawns. Prawn fishing is intensive, with relatively high rates of exploitation compared with most other fisheries. Fifty-eight vessels currently have full or developmental licences to fish for prawns and are subject to strict regulations on vessel size, gear used and areas fished to control pressure on the prawn stocks. Breeding grounds and areas of small prawns are protected by seasonal and permanent closures.
The southern rock lobster fishery also account for 30% of the value of the State's total commercial fishing catch in 1983-84. Rock lobsters inhabiting reef areas on the continental shelf are caught from small vessels (up to 20 metres) using steel frame and wire mesh beehive-design pots. Some 75% of the State's catch comes from the South-East coast between Kingston and the Victorian border. The fishing season is confined to the summer months and pots are usually allowed to catch overnight and are pulled early in the morning, when they are reset. Rock lobsters are processed as whole cooked food for the local market but the majority are exported as uncooked frozen tails. Crabbing has long been popular with recreational fishermen along the beaches of northern Gulf St Vincent. In 1984, the commercial exploitation of crustaceans was extended to the blue crab (Portanus pelagicus) on a developmental basis to examine the potential of this species as a fishery. The major areas are Spencer Gulf and the west coast of Eyre Peninsula. In addition a small fishery for the sand crab (Ovalipes australiensis) has recently developed in Coffin Bay on lower Eyre Peninsula.
Abalone are bottom-living gastropods up to 25 cm long which graze on seaweed. Two species, greenlip and blacklip, are taken commercially in South Australia by thirty-five licenced divers who prise the organisms off submerged rocks. Self-propelled underwater cages, to protect divers from sharks, may be operated from 5 to 10 metre boats at depths of up to 30 metres in search of the catch. Originally abalone were harvested from near Cape Jervis and Wallaroo, but now they are taken mainly from western Eyre Peninsula waters and exported frozen or canned. Abalone accounts for 7% of the value of South Australian fishery production. There is a small production of squid based on exploitation of senescent spawning populations as adults migrate to the shallow waters for egg laying. There is a summer fishery in the southern areas of the gulfs and near Wallaroo, and a winter fishery in the northern areas of the gulfs. Originally caught principally as bait, squid has gained acceptance as a table food.
Other species commercially exploited induced cockles (Donax deltoides) which are harvested from the inter-tidal zone of Goolwa and Coorong surf beach along Younghusband Peninsula; a small octopus (Octopus sp.) fishery serving the bait market and small domestic sales for food; and the harvesting of the introduced Pacific oyster (Crassotrea gigas). Commercial oyster farms are located at Coffin Bay on Eyre Peninsula, Price in northern Gulf St Vincent and Stansbury in southern Gulf St Vincent; there is an experimental oyster hatchery at Dry Creek north of Adelaide.
There were 1286 commercial fishing licence holders operating in South Australian waters in 1984; 45 licences were for tuna, 53 for prawns, 348 for rock lobster and 695 for general marine operations. The fishing fleet is diverse and ranges from vessels with fibreglass and timber hulls of 7 metres length or less engaged in the general marine and freshwater fisheries, to the timber an steel hulled vessels of up to 30 metres in length engaged in tuna fishing and prawn trawling. All the main fishing ports have chilling freezing facilities and many have processing plants oriented to the export trade.
The South Australian Department of Fisheries in addition to controlling the licensing of fishermen and the registered of boats and fishing gear, also undertakes extensive research into fishery management and conservation. South Australia has been responsible for pioneering the concept of marine national parks in Australia through the creation of twelve aquatic reserves, totalling some 15,000 hectares. All marine mammals and all mangroves (Avicennia marina) are protected by South Australian legislation. Mangroves and their associated samphire flats have been recognised as playing a vital role in the primary productivity of the near-shore marine environment.
South Australian waters offer excellent recreational fishing for both marine and freshwater enthusiasts. Many top table species including King George whiting, snapper and Mulloway (Argyrosomus hololepidotus) provide good fishing in areas that afford protection from the southern ocean. Freshwater species such as Murray cod and callop are available from most of the fishing reserves along the River Murray. In 1982, a sample survey of the South Australian population indicated that nearly 290,000 South Australians over the age of ten years undertook some recreational fishing during the summer months.