Farming Abalone

Ocean-Based Systems

Barrel or cage culture of abalone (Foster 1996, p 103) offers a low capital cost, although high maintenance cost, option for farmers. The barrels or cages can be hung from longlines supported by buoys or attached to rafts and large cages can be placed on the ocean floor if precautions are taken to prevent predation from crabs and seastars. Supplying feed to submerged cages has been simplified by the development of surface feeding systems. A 200 litre barrel can hold approximately 400 market-size abalone, and cages can be designed to house larger quantities of animals. (O'Brien, in Foster 1996, pp. 28-35).

The highest growth rates achieved in a trial involving a range of locations, systems (land and seabased) and species in Western Australia was with Greenlip abalone in barrels at Albany (Freeman et al., in Fleming and Roberts 2000, pp. 24-38).

Cages must be made of a material that is harmless to marine life, since abalone are very sensitive to heavy metals and anti-fouling chemicals. This requirement has a negative impact on ocean rearing because of biofouling of the cage structure and netting. Biofouling can greatly increase the maintenance costs of production systems and can directly smother the abalone by covering the respiratory pores. New Australian technology, to reduce biofouling on mollusks and plastic mesh based growout systems,may be critical for the success of sea-based abalone farming in Australia.

The siting of the cages is also important because tides, winds, waves and storms can make it uncomfortable to work and can even affect the culture animals. A balance must be sought between having good water flow for the animals but not having too much disturbance so the food remains available for the abalone. If the selected site has significant wave action, changes should be made to the normal artificial feed format (size and shape) to prevent it from being washed away. In general, seaweeds are suitable but most states discourage reliance on harvesting large amounts of wild algae and growing the algae is generally not commercially attractive.

Abalone may take three years in growout systems to reach preferred market sizes and not surprisingly, now that systems and feeds have been improved, selective breeding for faster growth is a key research activity (Li in Fleming and Roberts 2000, pp. 39-46).