Aquaculture is again in focus in Singapore as the country prepares to scale up local food production against a backdrop of coronavirus-driven disruptions to global supply chains.

Singapore is well known for its fish farming and almost all of the country’s offshore fish farms are located in the waters to its north. According to Singapore-based The Straits Times, those waters could soon reach maximum production levels and authorities have set their sights on the nation’s southern waters for further aquaculture activity.

Figures from the World Aquaculture Society (WAS) show that local food fish farms in Singapore produce around 10% – thought to be around 4,700 tonnes of fish – of Singapore’s consumption of food fish. Aquaculture in Singapore can be categorised as land-based and sea-based, it explains.

Singapore envisions up to 30% of the production of its nutritional needs to be done locally by 2030, meaning the country’s aquaculture industry needs to transform and adopt technology to raise productivity, strengthen climate resilience and overcome resource constraints. This is considered the long-term backdrop for the renewed focus on aquaculture, while disruptions to supply chains as a result of Covid-19 are a short-term anticipation that both emphasises and accelerates this strategy.

As a city-state that imports more than 90% of its food, Singapore is vulnerable to external shocks and global trends that impact food supply and safety around the world. To strengthen food security, Singapore is pursuing three broad strategies, also known as the three food baskets. These are ‘Diversify Import Sources’, ‘Grow Local’ and ‘Grow Overseas’.

“Controlling the concentration of oxygen dissolved in water is crucial to the success of aquaculture…”

Aquaculture – dependent on oxygen

Since around 1970, aquaculture has been the fastest growing branch of the global food industry, and around half of the fish supply is now farmed artificially rather than caught in the wild.

Fish farming in closed systems offers an ecologically acceptable alternative to sea-based fish farming. The fish live in artificial ponds, with the water being purified and recycled in a closed loop; there is no impact on natural waters.

Whether it is natural or artificial fish farming, both the business and the very science of aquaculture is dependent on pure oxygen supply. For artificial installations it is not enough to inject air into the water; for sea-based fish farming the level of dissolved oxygen in those waters is just as crucial, to both the health of the fish and also the surrounding marine environment.

To achieve the required oxygen content, the gas is needed in its pure form. Controlling the concentration of oxygen dissolved in water is crucial to the success of aquaculture. Generally speaking, the closer the oxygen concentration is to air saturation, the better the environment will be for healthy and reliable fish growth. Maintaining the right levels of oxygen improves feed utilisation, shortens the growth period, reduces fish mortality and mitigates the need for vaccination and antibiotics.

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Within the last decade, Linde introduced the SOLVOX® OxyStream system, capable of performing three critical functions in one system – dissolving oxygen in the water, producing the correct marine hydrodynamics and stripping out potentially harmful nitrogen – and all via a very low energy requirement.

The system is easily installed, as a new set-up or as a retrofit to existing fish farm tanks, and is maintenance-free because it is not associated with any ancillary equipment to manage water pressure.

The micro-bubbles created by the SOLVOX® OxyStream create the additional benefit of helping to reduce the concentration of dissolved inert gases such as nitrogen, argon and carbon dioxide. In particular, over-saturation of nitrogen, even in relatively small quantities, can endanger the wellbeing of fish stock, slowing growth and increasing the possibility of disease, and ultimately, even mortality.

Linde offers a full range of oxygen solutions for the aquculture sector, from oxygen supply itself across a range of supply modes through to control cabinets, flow distributors and diffuser hoses. It also offers the SOLVOX® DropIn, a new and easy-to-deploy, highly efficient solution for the oxygenationof sea cages. The system is suited to both continuous oxygenation schemes and short-term applications such as de-licing or medical treatments, and comprises a submersible pump as well as a patented oxygen dissolver and distribution system featuring a venturi nozzle. Using a small crane, SOLVOX DropIn is easily lowered into the water to the desired depth, and works by sucking water into the lower part of the dropped-in unit and mixing it with oxygen.