17 February 2014

Blue Jewels – A story of abalone farming

Helen Lockhart, Communications and Sustainability Manager & Maryke Musson, Assistant Curator

A group of volunteers and young biologists huddled around the Hi-Tec Microscope Exhibit recently and were captivated as Maryke Musson, Assistant Curator at the Aquarium, told them about a new display at the exhibit.

And when she revealed the animals in the display, there were gasps of surprise, and then awe.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
An uninteresting tank contains a surprise of beauty. Photo by Helen Lockhart

What looked like an uninteresting tank of black cones and piping contains some beautiful “blue jewels”.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Blue jewels. Photo by Helen Lockhart

These are, in fact, eight-month-old baby abalone (called spat), which we received from Abagold, a land-based abalone farm in Hermanus. Only the farmed juveniles show these brilliant colours at this age; this is as a result of their diet.

In the wild, juvenile abalone shelter under sea urchins. The spines of the urchins protect these juvenile abalone from predators such as octopus, klipfish and rock lobsters.

On farms they spend the day under the black cones, and at night they move out and feed around the cones.

When she was asked for the scientific name for abalone – Haliotis midae – Maryke encouraged the volunteers to remember it by thinking of “halitosis”, another name for bad breath! The word “haliotis” means “sea ear” and refers to the flattened shape of the shell.

In South Africa we call abalone “perlemoen”, which is a name derived from the Dutch term “paarlemoer”, meaning mother of pearl.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
If you look carefully on the right-hand side of the image, you can see two little stalks, at the end of which are the animal's eyes. Photo by Rob Tarr

Adult abalone do not move around much. A study carried out in Betty’s Bay showed that of 58 abalone on one rock, 47% were still there three years later, and of these, 82% occupied exactly the same position on the rock! This renders them easy prey for humans, who today are their biggest threat.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Live abalone. Photo by Angus McKenzie

In the 1940s, the commercial abalone fishery was thriving, but just 20 years later it was struggling to keep up with demand. Abalone is still fished commercially, but within strict limitations; there is no recreational abalone fishery.

Today the abalone story reads like a cheap thriller – sex, drugs, poaching, smuggling, Chinese mafia syndicates, corruption and black markets are all part of the plot. Abalone is a highly prized delicacy and aphrodisiac in the Far East.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Canned abalone. Photo by M Burgener

“Although abalone are threatened with extinction in the wild mainly due to poaching, they will never go completely extinct because they are easy to culture,” says Maryke.

Most of the abalone exported from South Africa is now farmed, which will help to save the species. There are currently three farms in Hermanus, another three near Gansbaai, two on the West Coast, and one near East London.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Amaza farm in Hermanus: Staff cleaning tanks (each tank gets cleaned once a week). Photo by Nanette Ras

Abagold has a hatchery where broodstock animals are used to yield eggs and sperm. Larvae are produced through an intricate process that has been finely tuned over the years. This stage of abalone is called “spat”. The hatchery target is to produce 200 000 spats per month. The spats are moved from larval rearing to settlement tanks and then to the nursery. This process takes approximately eight months.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Nursery tanks where the spat is fed formulated feed and ulva after they have been deplated. Photo by Willem Burger
abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Nursery tanks are cleaned weekly. Photo by Madelie du Toit

From the hatchery the animals are sent to the Amaza section on the farm, where they remain until they are about two-and-a-half years old. From there they go to the Sea View section, where they stay until they have reached a weight of about 90g.

From Seaview Farm the animals are sent to Bergsig Farm, where they remain for another two years until they are harvested for processing. During the grow-out period the animals are sorted and weighed every four months.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Amaza farm staff sort the abalone according to size and rejects into different baskets to prevent competition. Depending on the age of the abalone, this process can happen every four, six, or 12 months. Photo by Ingrid Olivier

It takes approximately five years before the abalone are ready to be canned or dried and sent overseas. Abalone farms only recently received permission to trade their product locally.

abalone, perlemoen, two oceans aquarium, cape town, western cape, south africa
Staff stringing abalone for the drying process - dried abalone forms part of Abagold's product variety. Photo by Willem Burger

“We plan to open a farmed abalone display in the Aquarium, and Abagold has agreed to supply enough spat so that our educators can present a lesson on abalone farming, since sustainable aquaculture is very much part and parcel of the future of seafood,” says Maryke.

With thanks to Hymne Ferreira, Research Assistant at Abagold, for supplying us with images and information.

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