Where and when to catch Blue Swimmer Crab in South Australia: the SA season, the spots in our guide that hold them, and where to find SA's current size and bag limits.
Blue swimmer crabs are South Australia's summer fishery. They're sustained by the warm, shallow water of the gulfs, and from October the Adelaide Plains flats, the Yorke Peninsula jetties and the top of Spencer Gulf fill with people walking backwards with crab rakes. PIRSA lists no recreational closed season; the calendar is set by water temperature, with crabs thinning out from about May as the water cools.
Western Australian limits don't apply in South Australia.
Where to Catch Blue Swimmer Crab in SA
Crabs like warm, shallow sand and seagrass with a big tidal range. The spots below list them: the raking flats at Thompson Beach and Port Parham, jetties on both sides of Yorke Peninsula, the upper Spencer Gulf flats and jetties from Port Germein to Whyalla and Port Augusta, and the West Coast jetties at Streaky Bay, Venus Bay and Ceduna.
Oily fish frames and heads, pilchards and fish offcuts tied or clipped into the net. Some states allow only fish or fish-based bait in crab nets, so check before using anything else.
Lures
Not applicable: crabs are taken with nets, scoops, rakes or by hand, not on rod and line.
Rigs
Drop nets and hoop nets (a ring with a mesh bag and the bait in the centre) are the standard jetty and boat gear; a long-handled scoop net or a crab rake is used wading the flats. Which of these you may use, how many, and their maximum sizes are set state by state, so check the authority link below. A crab gauge, a tub or keeper bag of seawater, and closed shoes are the rest of the kit.
Technique
With nets, set them on sand or the sand-weed edge, soak 10–20 minutes, then lift steadily and straight up so crabs don't climb out. On the flats, wade below knee depth at the bottom of the tide, wearing polarised glasses, and look for crabs moving or for dark puffs of sand where one has just buried; then scoop or rake it quickly before it bolts. Work back towards shore in front of the incoming tide. Gauge each crab as it comes up and put undersized crabs and berried females straight back. Pick keepers up from behind, at the base of the back paddle, away from the nippers, and shuffle your feet on the flats for stingrays.
Best Time
Warm water drives everything: crabs are most active and most plentiful from late spring through summer into early autumn, with late summer often the peak once the year's young crabs have moulted up to size. On the day, the bottom of a big low tide is best for raking and scooping, and slack water or a gentle tide suits drop nets. Calm, clear weather helps you see crabs on the flats.
PIRSA requires every crab to be measured as soon as it's caught, and egg-carrying females are fully protected. Crabbing is banned in Port Pirie's heavy-metal zone 1, and some aquatic reserves (such as St Kilda – Chapman Creek) restrict the gear you can use.
The SA Government's algal bloom advice is that crabs you catch yourself are safe to eat if cleaned thoroughly and gutted before cooking.
Identification
Also known asBlue crab, blue swimmer, bluey
A broad, flattened shell with a row of spines along each front edge and a long, sharp spine at each side, and back legs flattened into swimming paddles. Males are bright blue with white mottling and long, slim nippers; females are duller olive-brown to green with shorter claws. Flip it over to sex it: males have a narrow, pointed abdominal flap, females a broad, rounded one, and a berried female carries an orange to brown egg mass under it. Sand crabs are smaller and brownish, mud crabs are heavier, dark and blunt-clawed. Crabs are measured across the shell, so carry a gauge.
Size & Growth
A typical keeper is 12–18 cm across the shell, a crab past 18 cm is a good one, and the biggest reach about 25 cm. Crabs grow by moulting, jumping a size class at a time and staying soft for a few days afterwards, so a freshly moulted crab feels light for its width and is mostly water. Blue swimmers grow fast in warm water, reach a keepable size in around a year to eighteen months and don't live many years beyond that, which is why crab numbers bounce back quickly after a good spawning and fall away just as fast after a bad one.
Diet & Habitat
Opportunistic scavengers and predators of small fish, shellfish, worms, prawns and anything dead on the bottom, which is why a fish frame in a net works so well. They live over sand, mud and seagrass in sheltered bays, estuaries and tidal flats, mostly in 1–5 m and right up into ankle-deep water on a rising tide. In cold water they bury into the sand and go quiet, and they move into deeper water in winter before returning to the shallows as the water warms.
Eating Quality
Excellent: sweet, clean white meat as good as any crab in the country. Chill live crabs in an ice slurry to sedate them, then cook in boiling salted water for six to eight minutes and cool before picking. One good crab is a generous serve; picked meat makes crab pasta, chilli crab or crab sandwiches. Skip soft, freshly moulted crabs. Keep the catch alive in seawater or on ice until cooking, because dead crabs spoil fast in the heat. Picked meat freezes for a month or so; whole cooked crabs don't freeze well.