Oyster farming, a bright future
under the West Coast sun

Ferdi Endemann - Specialist Extention Officer: Aquaculture
Department of Agriculture: Western Cape

The West Coast of South Africa is known for the relatively cold ocean Benguela current. The Benguela has it’s origins in Antarctica and transports cold nutrient rich water from the Southern Ocean. It is this nutrient rich water source that supports a specific and highly productive ecosystem based on algal blooms and upwelling events. Certain times of the year, notably on hot wind still summer days, these algal blooms can reach high density levels that leads to another West Coast phenomenon, Red Tides or Hazardous Algal Blooms. This leads to lobsters walking out of the oxygen starved sea at places like Lamberts Bay and Elands Bay.

These red tide events also sometimes lead to Marine and Coastal Management (MCM) issuing warnings to not collect wild shellfish such black and white mussels for human consumption. The reason for this is that although bivalve molluscs can normally “ride out” the low oxygen levels in the water they do filter out the red tide algae and assimilate the toxins that are formed by the algae in their body tissues. If these toxins accumulate above a certain level then eating the flesh from these mussels, and for that matter oysters, can be hazardous to people’s health leading to various forms of shellfish poising.

It is normally at these times that mussel and oyster farmers in the Saldanha area find that they have a drop in sales. However, according to the farmers’ permit conditions they have to send samples away for toxin testing at set intervals from 2 – 3 times a week depending on the type of toxin testing for. The results are forwarded to Shellfish Monitoring Program at MCM and to the farmer as soon as the results become available. If toxin levels are above internationally set standards then harvesting will be stopped by the program for the entire area, until such a time as three consecutive days tests have been shown to be clear of toxin. In this way the public health and the shellfish industry is protected. So the next time you hear a warning has been issued not to collect shellfish for consumption know that it does not effect the farmed shellfish coming from Saldanha and other culture sights up the West Coast.

Oyster farming is taking off in Saldanha Bay. Which is to be expected, from this world class shellfish growing site. The outer bay, on the Langebaan side of the iron ore jetty is particularly suited to long line oyster growing techniques as the water is rougher than the more sheltered inner bay (Saldanha side of the ore jetty). In the inner bay Spanish mussel rafts are being used to culture a small stock of oysters and about 800 -1000 ton of mussels. A few seed oyster producers are growing small seed oysters to larger seed to be sold on to the large oyster producers. In Paternoster a salt pan operation is also growing small seed (0.2g) on to 30g large seed oysters for the outer bay farms in Saldanha.

This intermediate stage specialization is opening up the potential for job creation in an area where the fishing industry has shed jobs in the last couple of years. Currently, Saldanha is producing about 2.5 million oysters per year with most of the stock being consumed in Cape Town. Every year Saldanha farms get large oyster orders from Knysna restaurants during their oyster festival. With Saldanha currently producing between 5-10% of the potential mussel and oyster carrying capacity, estimated for the bay, there is still great potential for an increase in production and the diversification and processing of oyster products. Given the right developmental conditions being set in place oyster farming in Saldanha has a bright and prosperous future on the West Coast.

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