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Abalone are farmed in land-based tanks which need large volumes of high quality water to be pumped continually through them. This type of farming requires much greater infrastructure and capital investment and has higher on-going operating costs compared to at seas.

Important factors to be considered when building a land-based abalone farm include:

• site selection - water quality and the distance and height for the water to be pumped to the farm;
• acess to power supplies; freshwater and roads.

Abalone grown in land based farms are usually fed artificial feeds although some are fed specially grown seaweed or a combnination of seaweed and artificial feed.

The types of tanks used in land-based farms vary greatly, with most development still taking place.

Breeding stock is regularly collected by divers from the wild and forms the basis of the hatchery operations and maintaining genetic diversity. Female abalone can produce in more than 1 million eggs per spawning period. Fertilisation leads to planktonic larvae that feed on their own energy stores.

Within a day of fertilisation the planktonic larvae hatch. These larvae feed on their own energy stores. About one week later the larvae settle onto specially prepared plates,covered with cultured diatoms, and metamorphose. Although juvenile abalone, called 'spat', are still vulnerable, careful growing can result in up to 90% survival over the next 3-6 months.

The spat spend from 8 to 12 months in the settlement tanks, until they grow to a length between 10 to 15mm. At the end of this time transferred to grow-out tanks.

Most grow-out tanks are raceways or circular tanks These tanks are usually shallow and made from strong black plastic. They are often covered with greenhouse mesh to stop predators and provide shelter for the abalone. Seawater is pumped from the sea then through a sand filter before being pumped continuously through the tanks. The abalone grow quickly in the fast-flowing water provided by these flow-through systems. Most abalone are harvested at the end of their third year when they have reached a size of about 70 mm or 50g.

Most land based abalone farms are 24-hour operations involving continuous monitoring of the water systems and the stock. Any interruption to the water supply and water temperature can be disastrous with large-scale losses of abalone.

Also see www.lib.noaa.gov/retiredsites/korea/main_species/abalone.htm

Diver collecting breeding stock for an abalone farm

Workers in a land-based abalone farm

Problems with land-based abalone farming

The World WIldlife Fund has raised a number of concerns with this type of aquaculture. These include:

• Farm siting/infrastructure: Unappealing aesthetics, noise, odor and/or dust; limited access to or alienation from public land; habitat destruction and rehabilitation
• Energy use: High use of electricity to run large-scale flow-through and recirculating abalone culture systems
• Feed inputs: Unsustainable kelp or wild seaweed harvest; fish meal and fish oil content in manufactured feed
• Biosecurity: Transfer of diseases to and from the wild, within the wild and within aquaculture systems; pathogen amplification; exotics (e.g., translocation of pests and pathogens)
• Ecosystem effects: Benthic impacts, such as sedimentation and erosion; eutrophication; habitat destruction; and wildlife interactions (e.g., marine mammals/endangered species)
• Waste management: Effluents (e.g., nutrients, sediment and chemicals), biological waste (e.g., shell, dead animals and sludge disposal) and solid wastes (e.g., plastics, operational equipment and building materials)
• Social responsibility: Abalone aquaculture sometimes employs a large number of workers on farms and in processing plants, potentially placing labor practices and worker rights under public scrutiny.

From Abalone Aquaculture Dialogue, WWF.