Three to six month old abalone

Abalone farm tour in Hermanus

Abagold abalone farm in Hermanus
Abagold abalone farm in Hermanus

Abalone (or perlemoen, Haliotis midae) is a highly exploited marine resource in South Africa, to the extent that it is currently illegal for individuals to harvest abalone from the ocean. All fishing was suspended in early 2008. Formerly it was possible to get a permit to do so. Limited commercial fishing has been allowed since 2010.  The government acknowledged that this would cause further depletion of the wild stock of abalone, but framed the decision as one to protect the livelihood of approximately 1,000 abalone fishermen. When there is no abalone left to fish, I wonder what those fishermen will do?

Ten, twenty and forty year old abalone
Ten, twenty and forty year old abalone

The demand for this unprepossessing grey mollusc is almost limitless, primarily from the east, where it is viewed as a status symbol and is highly sought after at banquets and to prove the host’s prestige. Given the huge demand and the fact that South African waters are the natural habitat of this species, abalone farming has flourished in South Africa, with eleven farms in operation. The largest is Abagold, with four farms located in Hermanus. Abagold employs over 350 local people (it is the largest employer after the municipality). Farm tours are offered every week day at 11am (they cost R50), and Tony and I did one on our way back from De Kelders.

The Abagold farming operation is extensive, actually consisting of several separate farms all located close to the (new) harbour in Hermanus. The tanks are supplied with fresh water directly out of the ocean – the temperature (generally 15-18 degrees) and water quality is not adjusted at all, since this is the optimum natural habitat for the creatures. The animals are fed on kelp, sea lettuce, and specially manufactured abfeed, and no chemicals are added to the water. As a result, the farm can pump the water straight back out into the ocean without causing any contamination. There is a constant circulation of millions of litres of water through the farm, keeping the abalone oxygenated.

The holding pens have a beautiful sea view
The holding pens have a beautiful sea view

Breeding stock are kept separately, and range in age from three to 30 years. Pairs are retrieved from the ocean periodically, and returned after a time. Abalone are distinctively male or female, distinguishable by the colour of their gonads, which are nestled under their shell above their large fleshy foot. Abalone spawn between August and November in nature, prompted by increased oxygen levels in the water. To stimulate spawning in captivity, hydrogen peroxide (H2O2) is added to the water containing broodstock, which causes their muscles to contract and release eggs and sperm.

Three to six month old abalone
Three to six month old abalone

Eggs and sperm are mixed in the correct proportions, and fertilised eggs sink to the bottom of the tanks where they are sucked out and placed in tanks where they hatch after several hours. Algae is specially cultivated on large plastic sheets, to which the free swimming larvae attach when they are ready (after about a week). They spend about three months feeding on these algae-covered sheets of plastic. The baby abalone (spat) are beautiful, with blue and turquoise, perfectly formed little shells 3-5 millimetres in size.

In order to remove the fragile abalone from the plastic sheets, they are anaesthetised with an infusion of magnesium sulphate into their water, which enables them to be gently rubbed off the sheets. It is around the age of three months that they develop light-sensitive eyes, which prompts them to seek out darker hiding places. Black plastic cones are supplied under which the young abalone live for another three to four months.

The blue-grey colour of the gonads visible here shows this is a female
The blue-grey colour of the gonads visible here shows this is a female

At about six months of age the abalone are sorted by size and moved into simple tanks with fittings that are constructed largely of standard irrigation piping and hard plastic sheets. The abalone are quite sensitive to their environment and water has to be kept very clean. They spent the next 3-5 years growing in their tanks.

Kelp is collected to feed the abalone at various farms in the Hermanus area
Kelp is collected to feed the abalone at various farms in the Hermanus area

When the abalone are large enough (about 250 grams, I think – a bit bigger than my palm), they are removed from their shells. The gonads, mouth, eyes and other organs are discarded, and the foot is either canned in fresh water and pressure cooked in the tin, or dried, in about a 50-50 split. All the production is exported to Hong Kong, China, Malaysia, and Singapore, with a 440 gram tin of abalone in brine fetching R200 to R450 for Abagold (it obviously costs more to buy it in the shops). The farm produces nearly 500 tons of abalone per year. This is big, big business.

We were very excited to see how sustainable this aquaculture model is. Fish farming isn’t a wonderfully clean or sustainable business, but this seems to be an effective way to reduce demand for wild abalone without harming the environment. There is a long way to go, however, before supply of abalone outstrips (or even comes close to matching) demand – according to our tour guide, there are buyers for whatever quantity of abalone the farms can produce. Legally harvested and farmed abalone comprised one ton out of the seven tons of abalone that left South African shores last year. The scale of the poaching problem is massive.

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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