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