Profesor Dato’ Dr. Tan Shau Hwai
Centre for Marine and Coastal Studies (CEMACS)
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February, 2021

Before the 1980s, oysters in Malaysia were mainly cultivated in the wild, harvested between mangrove roots and exposed rocks during low tides. But its supply was never able to meet local demand. This led to research by the Centre for Marine and Coastal Studies (CEMACS) at Universiti Sains Malaysia under the direction of Prof. Datuk Dr. Aileen Tan, into the feasibility of oyster farming.

Described as low cost, oyster farming is appreciated for its green and clean aquaculture approach and uses adaptable technology, allowing local communities to generate income in a sustainable manner and to reverse poverty among the B40s.

The means are simple. Oyster farmers are taught to build floating rafts and are given a certain amount of oyster seeds from the hatchery for cultivation, Tan explains. One 20” x 20” raft fits about 3,000 oysters and depending on the site, the cultured oysters take an average of six to eight months to grow. “Once income flow steadies, these farmers can choose to expand the site capacity.”

For the oysters to grow to a good size, consistent cleaning and pest removal are necessary. Once they reach 3cm in length, the oysters are spread out and sorted according to size, with enough room to grow until they are market-ready, for which farmers can expect monthly earnings of RM5,000 to RM6,000.

Unlike fishes and prawns, oysters need no feeding nor do they produce waste and greenhouse gases. They act instead as a filtering mechanism, removing nitrogen from the water to the benefit of other aquatic plants and wildlife.1

Also crucial in the farming of oysters is the site selection – mangrove swamps or coastal shores. These farms must not be in close proximity to industrial areas or plantations because “oysters are filter feeders hence they uptake anything. Besides the natural phytoplankton consumed, they can also take in heavy metals and pollutants.”

To be sure, through a depuration process, the removal of bacteria from oysters is possible within 24 hours. But the duration is far longer for heavy metals – this takes up to three months! “Bacteria normally goes into the gut and can be flushed out through purging, but heavy metal assimilates into the meat itself,” Tan explains.

It is difficult to distinguish a good oyster from a bad one; the shells are often sealed, making it hard to assess their quality. A change in the environmental temperature likewise encourages oysters to spawn, but gives their meat a watery texture. “We are working with the industry to create a string known as triploids, or sexless oysters.” These have an additional set of chromosomes compared to diploid oysters, and they remain in good shape throughout the year.2

The monsoon seasons that bring with them a deluge of freshwater to rivers and streams also impact oyster farming. “Farmers will need to position their baskets of oysters deeper in the water, away from the freshwater that lingers on the surface.”

Advocating Inclusivity

Aquaculture has replaced capture fisheries in accommodating population growth and in mitigating climate change. But what this also means is that traditional fishermen are being left behind; many are hindered from entering the sector for the high cost it involves. This situation eventually relegates them back to the B40 category, “receiving less than RM500 per month”.

“Poverty is not about being poor, but about not having the skills and ability to generate income,” opines Tan. Oyster farming can easily be a potential supplementary income source. Another unsettling issue is the disparity in gender and wage in the seafood and plantation sectors. These are pigeon-holed as “male jobs”, and prevents women from settling into the professions confidently. Tan hopes to see this perception change and is actively obtaining funding for women to play a bigger role in oyster farming. “At the moment, women are not primary income generators in this sector. But many are realising the advantages of oyster farming and are seeking possible opportunities to venture further in the industry.”

A Potential for Growth

The last 30 years have shown an increment in marine aquaculture driven by the need for self-sufficiency in marine food production. Aquaculture practises multiple levels of culture – oysters and seaweed on the surface, fish and prawns in the middle, and sea cucumbers at the bottom. “Having all kinds of organisms cultured together brings less negative impact as they balance the ecosystem of the cultured area,” Tan says.

But owing to their limited availability, wild oyster seeds are difficult to obtain for farming. These seeds grow according to the oyster’s life cycle, making them very tempting to be harvested by farmers once they reach a certain marketable size.4 Nonetheless, Penang is primed to become an oyster seed hub “if more focus is given on expanding the current commercial hatchery in Balik Pulau, which was established in 2008. Malaysia has an edge weather-wise; oysters can be harvested throughout the year unlike in some other countries. We have made a breakthrough in this industry and to sustain it, not only are farmers needed, the number of oyster seed growers must also multiply.”

“Are Local Oysters Safe for Consumption?”

As oysters are often associated with elevated dining experiences, many are under the impression that imported oysters are of far superior quality, while locally cultivated ones are met with scepticism, observes Tan. Currently, 86% of oysters in the market are imported from Canada, China, New Zealand and the US. Oysters can also be used for pharmaceutical purposes.

“Oyster extract is used to remedy insomnia, a rising social issue nowadays. It would be an opportunity missed if the industry is not pragmatically exploited.”

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