Source: NIWA – National Institute of Water and Atmospheric Research
Why is NZ investing in RAS?
“A good way to understand recirculating aquaculture is to think of an aquarium. You have a set amount of water and it recirculates. Recirculating aquaculture is the same principal, but on an industrial scale. The idea is that you have a tank with a lot of fish and they need O2, secrete CO2 and produce waste. You process this water and you keep putting it back into the tank with a bit extra to compensate for evaporation. In a tight system like we have here, you should only need to replace 5% of the entire volume every day.”
Because this is a closed system, a lot of factors can be controlled. The water coming in can be cleaned and also temperature-regulated to optimise the growth rate. The water coming out can also be treated, minimising the nutrients and other outputs from going back into the natural ecosystem. This also greatly reduces, or even eliminates the risk of pathogens coming in or going out of the farm. This is part of the research scientists are doing on site to optimise recirculating aquaculture.
“Often in aquaculture research, things that work on a small scale are very different once you scale them up and this is where industries are wary of it will ultimately work for them. The scale of research we do at NIWA is what makes us different because . we can use 5,000, 10,000 and 20,000L replicated tanks. This gives us the confidence that it’s going to work in the big 600 or 1,500 ton farm. ”