Distributed from Geographe Bay in Western Australia to St Helens in Tasmania (Ref. 6390); including Lord Howe Island (Ref. 9710) and the Torres Strait Islands (Ref. 13465).

Stock structure: There are genetically distinct stocks of Spanish mackerel (Ref. 30218, 28141). Fish from the northern Great Barrier Reef to New South Wales form 1 stock, while fish from Torres Strait and the Gulf of Carpentaria are part of a northern stock distributed from the southern Gulf of Papua to Western Australia (Ref. 30196, 28141, 30219). Evidence from tagging studies and historic fishing activity in the Gulf of Carpentaria and Torres Strait waters, although limited, suggests that Spanish mackerel move between the Gulf and Strait waters (Ref. 30218).

Commercial fishery: In Western Australia, Spanish mackerel are fished north of approximately 28°S. Mackerel fishing is a major fishery on the North West Shelf. From the trap and line fishery there, Spanish mackerel comprised an average of 31% of the catch of all fish during a 2-year study in the mid-1980s (Ref. 27266). The fishery peaks in July and August, and weather conditions restrict fishing operations during the wet monsoon period (December-February) (Ref. 30203, 27266).

In the Northern Territory, Spanish mackerel have been targeted by local fishers since the late 1970s. The fishery extends along the whole coastline, with local concentrations south of Darwin, from Bathurst and Croker islands to the Wessel Islands, and in the western Gulf of Carpentaria. Most fishing takes place during the second half of the year, peaking in September-November. Spanish mackerel are also targeted on their presumed migration path along the western Gulf of Carpentaria coastline. Since 1987, effort and catch have increased sharply in the Northern Territory Spanish mackerel fishery.

Taiwanese fleets fished for Scomberomorus species off northern Australia from 1974 to mid-1986 (Ref. 26279) and in the Gulf of Carpentaria until the fleet’s exclusion in 1978. The Taiwanese used drifting gillnets ranging in length from 8 km to more than 20 km (Ref. 26279). Australian Government regulations in 1986 limited the gillnet lengths to 2.5 km or less, effectively making the Taiwanese gillnet fishery uneconomic in Australian waters.

The Queensland fishery for mackerel is the State’s major offshore finfish fishery (Ref. 30220) and has been operating for at least 60 years (Ref. 30219). In 1989-90, its value was estimated at A$3.4 million, of which more than 66% was Spanish mackerel. The Queensland fishery extends from the southern Gulf of Carpentaria, through Torres Strait and along the east coast, although most fishing takes place from north of Cooktown to Mackay. Mackerel fishers operate mostly from the ports of Cairns, Townsville, Yeppoon, Mackay and Bundaberg. Mackerel are fished to approximately 30°S (Coffs Harbour) in New South Wales. The east coast fishery targets mackerel during the spring spawning season and the northward migration (Ref. 30194) and later in summer-early autumn in southern Queensland.

The main fishing method for Spanish mackerel is trolling. Varying lengths of Bowden cable main line, wire trace and terminal rigs of ganged hooks are used (Ref. 30199). Garfish (Hemiramphidae) are the preferred bait. Other fish baits and different combinations of rope and lures may be used. Another fishing technique for mackerel is drift-fishing using rod-and-reel (Ref. 30199, 30194, 30220).

Catch rates vary depending on the time of day (early morning and evenings are preferred), moon phase, tides, water temperature, depth (Ref. 30221), sea floor temperatures (Ref. 30205), trolling speed and the fishers’ experience (Ref. 30221). The size of the fishing operation varies, from a mothership up to 16 m long operating several dories through smaller vessels without dories, to dinghies operating from island locations.

All Scomberomorus are susceptible to drifting gillnets. There are localised gillnet fisheries for small mackerel through almost their entire distribution in Australia, from approximately Shark Bay to northern New South Wales. Sharks form an important part of the catch in these fishing operations (Ref. 30205), and fishers target either shark or mackerel depending on availability and market demand. A small amount of mackerel is taken with offshore drifting gillnets by domestic fishers in north-eastern Queensland, where reasonable quantities of juvenile mackerel are also caught inshore.

Demersal otter trawlers targeting prawns in northern Australia may catch substantial quantities of mackerel either as bycatch or by line fishing. Some boats engaged primarily in other fisheries in northern waters switch to trolling mackerel when the fish are biting.

Wahoo (Acanthocybium solandri) (in north-eastern Australia) and shark mackerel (Grammatorcynus species) (in north-western Australia) are important bycatches of the mackerel troll fishery.

Mackerel are marketed frozen, fresh or chilled as gilled-and-gutted whole fish or trunks, and are retailed as fillets or cutlets. In Western Australia, the mackerel are gutted or put in chilled brine for gutting later the same day (Ref. 27266). In Queensland, some fish are filleted on the boats and stored on ice or frozen. Small local operations prepare smoked mackerel. Much of the Northern Territory product is trucked interstate, whereas Western Australian and Queensland product is sold both locally and interstate. Mackerel is in high market demand in Australia. It is a staple of the ‘fish-and-chips’ trade in Queensland.

Recreational fishery: In the Northern Territory and Queensland, most recreational fishing for Spanish mackerel takes place in waters within reach of pleasure boats from major coastal population centres. Spanish mackerel is the most widely sought-after pelagic fish for recreational fishers in Queensland waters and their annual catch from Great Barrier Reef waters is considerable.

Rod-and-reel gear is used almost exclusively with live bait, dead bait or lures (Ref. 30220). Fishers troll from boats or drift rigged baits from the shore, sometimes using balloons to carry the baits well out into the currents. The Australian Anglers Association records the largest Spanish mackerel taken as 42.2 kg, caught in Western Australia in 1979.

Resource status: The catch of Spanish mackerel from north-eastern Queensland has declined since the late 1970s (Ref. 30219), while that from northern New South Wales has slightly increased (Ref. 30219). There is a perceived overexploitation on the Queensland east coast with a possible decline to very low levels in the spawning stock (Ref. 30572). Spanish mackerel stocks in the Northern Territory may be adversely affected by foreign fishers - mainly Taiwanese driftnetters operating under licence in Indonesian waters. These vessels catch substantial quantities of Spanish mackerel which are probably migrating into or out of Australian waters. Over-exploitation of the resource during the years of Taiwanese gillnet fishing in northern Australian waters was suggested (Ref. 26279) by declines in both catch per unit effort and body length of mackerel. The Taiwanese fleet operating in the Gulf of Papua in the first half of the 1980s was also implicated in reduced mackerel catches in the Torres Strait troll fishery (Ref. 30219).

Ciguatera poisoning is associated with mackerel. A lipid-soluble toxin, similar to ciguatoxin, has been found in individual mackerel caught between 24°S and 26°S off Queensland (Ref. 168) and also in mackerel from the Gove Peninsula area, Northern Territory.

Also Ref. 2334.