Breeding mud crabs

In Queensland, female crabs are protected under the Fisheries Act 1994. If you want to develop an aquaculture enterprise in Queensland you must apply for an aquaculture development approval.

Hatchery phase

Mature female mud crabs kept in large tanks or in ponds under suitable conditions will extrude eggs. Each egg batch contains about 2–5 million eggs and a female may extrude more than one batch in her life. The eggs take 12–14 days to hatch, depending on temperature.

After they hatch, the larvae feed on small planktonic animals. Rotifers or brine shrimp (Artemia spp.) are live food types used successfully in cultures. Hygiene during the egg and larval phase is critical to success through to post-larvae in the hatchery. Water quality parameters, such as temperature, salinity, pH, oxygen and ammonia, should be maintained at approximately open sea conditions throughout this phase. Crowding of larvae near the end of the cycle can lead to heavy losses due to cannibalism. The fully planktonic zoea larvae grow through 5 stages over 2–3 weeks at 27–28°C before changing into a megalopa.

The megalopa has claws, resembling a small crab with a tail, but still swims actively, voraciously feeding on Artemia juveniles, other larvae and fresh and artificial diets. The megalopa stage lasts about a week before metamorphosing into the first crab stage, which is about 4mm wide.

Nursery phase

Hatchery-produced megalopa or first-stage crabs are typically reared in nursery systems to a more advanced crablet stage, 10–40mm across, before seeding into a growout system.

During the 3–6 week nursery period, the crabs are benthic and cannibalistic but can be successfully reared in shallow nets, tanks or ponds at densities greater than 50 per square metre.

The crabs are fed a diet of artificial formulated feeds, but will readily consume minced fresh diets such as mussel or fish meat. Water quality is less critical at the crablet stages compared with the hatchery phase.

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