Blue Swimmer Crab
Estuary / Sheltered BayBlue swimmer crab fishing in WA — the state's most popular recreational crustacean, found across sheltered estuaries and bays from Geographe Bay up through Cockburn Sound and the Swan-Canning. The Mandurah and Peel-Harvey blue swimmer crab season is a Perth summer institution: drop nets, a tinnie and a measuring gauge. Sweet white meat, managed area-by-area, and closed 1 September to 30 November in the Swan and Canning rivers, Cockburn Sound and all waters south to Minninup Beach.
Overview
Blue swimmer crabs (Portunus armatus) are the most popular recreational target in the West Coast bioregion. They live in shallow sandy and seagrass bottoms in sheltered estuaries and bays — the Peel-Harvey Estuary out of Mandurah is the most famous fishery, with strong populations also in Cockburn Sound, the Swan-Canning, Leschenault Estuary at Bunbury, Geographe Bay, and Hardy Inlet at Augusta. The fishery is closed from 1 September to 30 November each year in the Swan and Canning rivers, Cockburn Sound, and all waters and estuaries south to Minninup Beach near Bunbury (which takes in the Peel-Harvey and Leschenault) to protect the breeding stock, and bag and size limits vary by area. Crabs are taken with drop nets, scoop nets, a blunt wire hook, or by hand — pots and witches-hat (hoop) nets are not permitted for recreational use in WA. It's a family fishery as much as anything: drop nets off a tinnie at sunset, scooping in waist-deep water on a Sunday afternoon, or wading the Peel flats with a torch on a still summer night.
Identification
Bluey, blue manna crab, sand crab, blue swimmer
A broad, flattened carapace with a row of spines along each side and a long sharp spine at each corner, and the rear legs flattened into swimming paddles — built to swim, not just walk. Males are bright blue with white mottling and long slim nippers; females duller olive-brown to green with shorter, stubbier claws. Flip it over to sex it: males carry a narrow T-shaped abdominal flap, females a broad rounded one, with berried females showing an orange to brown egg mass beneath. Mud crabs are heavier, dark green and blunt-clawed, without the long lateral spines. Size is carapace width, measured across the shell at its widest point.
How to Catch
Mullet frames, fish heads, chicken necks, fish offcuts, raw chook carcasses
Not applicable — crabs are not taken on lures or rod and line
Drop nets (max 10 per person or boat, up to 1.5m diameter), scoop nets (rigid, internal opening up to 375mm and up to 210mm deep), a blunt wire hook, or by hand are the legal recreational gear — crab pots and witches-hat (hoop) nets are not permitted. Crab drop nets do not require a name tag (that's a rock-lobster-pot rule). Standard drop nets are a wire ring with mesh dropped vertically and a bait clip in the centre. A measuring gauge is essential to check the 127mm minimum across the carapace before you put anything in the bucket.
Set drop nets in 1–4m of water over sandy or weed-edge bottom, with bait wired into the centre, and leave them to soak for 10–20 minutes before hauling. Pull straight up and steady — a slow lift keeps the crabs in the net. Scooping is the wading game: walk the shallows in clear water on a calm day with a long-handled scoop net and slide it under any crab you spot before it can bolt. Drop undersized or berried (egg-carrying) females back into the water before pulling your next net — this is a legal requirement, not a courtesy. Handle keepers from behind the rear paddle to avoid the nippers.
Warmer months from late spring through summer and into autumn produce the best crabbing, with January and February typically the peak in the Peel-Harvey once juveniles have moulted to legal size. Calm, sunny afternoons are ideal for scooping in the shallows; drop netting works through the day but is often most productive on a slack tide. The 1 September to 30 November closure — covering the Swan and Canning rivers, Cockburn Sound and all waters south to Minninup Beach — keeps everyone off those waters during the breeding period.
Up to 25cm carapace, commonly 130–180mm
Dec–Aug (closed Sep–Nov in the Swan/Canning, Cockburn Sound and waters south to Minninup Beach)
Size & Growth
Legal size is 127mm across the carapace, and a typical keeper runs 130–180mm. A crab past 180mm is a good one, and the biggest reach around 25cm across. Crabs do not grow smoothly — they moult, jumping a size class in one go and staying soft for a few days afterwards, so a freshly moulted crab feels light for its width and is watery and disappointing on the plate. A blue swimmer reaches legal size in roughly a year to eighteen months in warm estuary water and does not live many years beyond that, which is why the fishery recovers quickly but crashes just as fast under pressure.
Diet & Habitat
Opportunistic scavengers and predators taking small fish, molluscs, worms, prawns and carrion, which is why a mullet frame or a chook carcass in a drop net works so reliably. They live over sand and seagrass in 1–5m in sheltered estuaries and bays, burying into the sand when it is cold or when threatened, and moving into deeper water through winter before returning to the shallows to breed. The WA fishery centres on the Peel-Harvey Estuary out of Mandurah, with strong populations in Cockburn Sound, the Swan-Canning, the Leschenault Estuary at Bunbury, Geographe Bay and Hardy Inlet at Augusta.
WA Size & Bag Limits
| Minimum size | 127 mm across the carapace |
|---|---|
| Bag limit | 10 in the West Coast bioregion (5 in Cockburn Sound, Owen Anchorage and the Swan-Canning); 20 elsewhere in WA |
| Counts toward | Geographe Bay is 10, of which no more than 5 may be female. Boat limit 20 in Cockburn Sound, Owen Anchorage and the Swan-Canning with four or more Recreational Fishing from Boat Licence holders aboard. Closed 1 September–30 November in the Swan and Canning rivers, Cockburn Sound and all waters south to Minninup Beach. Berried females and undersize crabs must be released before the next net is pulled. |
Rules vary by area and change regularly — check DPIRD before each season. A seasonal closure runs 1 September to 30 November in the Swan and Canning rivers, Cockburn Sound, and all waters and estuaries south to Minninup Beach near Bunbury (Peel-Harvey and Leschenault included); it is not a blanket West Coast bioregion closure. Statewide minimum size is 127mm across the carapace. Cockburn Sound and Owen Anchorage: daily bag limit 5 crabs, boat limit 20 (with four or more Recreational Fishing from Boat Licence holders aboard). Swan and Canning rivers: daily bag limit 5 crabs, boat limit 20 on the same terms. Peel-Harvey Estuary and other West Coast waters outside Cockburn Sound and the Swan-Canning: daily bag limit 10 crabs. Crab pots and witches-hat (hoop) nets are prohibited for recreational use; legal gear is drop nets (max 10 per person or boat, up to 1.5m diameter), scoop nets, a blunt wire hook, or by hand, and crab drop nets do not require a name tag. Berried (egg-carrying) females must be returned to the water immediately, as must any undersize crabs — undersized and berried crabs must be released before the next net is pulled.
Eating Quality
Yes — blue swimmer crab is excellent eating, sweet clean white meat the equal of any crab in the country. Chill the live crab in an ice slurry to sedate it, then plunge it into boiling salted water for six to eight minutes and cool it before picking. One adult crab yields a generous single serve, and the picked meat is the base for the recipes people actually want: crab linguine, chilli crab, or crab and lemon through pasta. Avoid freshly moulted soft crabs — mostly water. One warning that matters: crabs from the Swan and Canning rivers can carry the toxin-producing alga Alexandrium, so DPIRD advises removing the guts (the mustard) and the gills before eating those; the meat itself is fine. Keep your catch alive in a keeper net or a tub of seawater until cooking; a dead crab spoils fast in summer heat. Picked meat freezes for a month or so; whole cooked crabs do not.
Perth Tips
Carry a measuring gauge and use it on every crab — undersized fines run into the thousands and DPIRD compliance officers patrol the Peel and Mandurah foreshores hard through summer. Keep to a maximum of 10 drop nets per person or boat. A keeper net or insulated tub with seawater keeps your catch alive until cooking — dead crabs spoil fast in the heat. Mandurah's Peel Inlet, the Dawesville Cut, the Swan estuary around Pelican Point, and the eastern shore of Cockburn Sound are the reliable public-access options.