Kingfish Farming (NIWA)

New Zealand’s aquaculture industry has ambitions to reach a value of NZD$3 billion by 2035, and at Ruakaka in Northland, NIWA is contributing to this goal. The Crown Research Institute has spent the last 20 years developing a land-based system that can deliver a reliable source of quality fin fish for the consumer and restaurant markets. It has recently opened a significant development on its own 8-hectare site. The commercial scale operation is now producing 600 tonnes of fish annually and there is plenty of potential for expansion. 

More than half of the fish protein consumed by humans worldwide is produced by aquaculture. However, there are certain challenges that come with both marine and freshwater aquaculture operations. Climate change has delivered marine heat waves resulting in parasite and disease pressures on stock, as well as societal concerns about environmental impacts such as dispersal of excess waste, or additional carbon impacts of setting up deep-sea farms seeking cooler waters a long way offshore.  

The approach taken by NIWA Taihoro Nukurangi, is to bring the fish farm on to the land, with support from the Northland Regional Council. It is considered an additional option to (rather than a replacement for) sea-cage farming.  While hāpuku and Yellowtail kingfish have been identified as excellent contenders, the ‘kingis’ are the species of choice for this venture, located at Bream Bay in Northland.  

The Yellowtail Kingfish (also known as Haku or Seriola lalandi) is found throughout the warm waters of the southern hemisphere and northern Pacific Ocean. They also have a relatively straight forward life cycle, a rapid growth rate and high value as a product. Farms have been established in Europe, so many of the infrastructure options have been largely established.  

The site is ideal for the operation, being able to utilize the existing infrastructure of previous occupier, the Marsden B power station. Large pipes allow for intake of sea water for use in the massive fish tanks, and after a multi-stage process of filtering and waste extraction, the water is returned to the ocean via the outlet pipe. 

Much of the science undertaken by NIWA has involved developing a production system to ensure a top-quality product from healthy well-tended fish, produced with a low environmental footprint. Enabling efficient conversion of raw materials and energy to high quality protein is key to the set up. Additionally, the enterprise has to be profitable and deliver direct economic benefits to the local community. 

Key to the operation is the RAS (Recirculating Aquaculture System) consisting of eight tanks, containing reticulated, recycled, and treated water. RAS Manager Stephen Pope explains NIWA’s years of research and experiments have resulted in the ability to provide optimum growing conditions through monitoring and various controls, whether it be temperature, oxygen levels, food, or light levels. 

The fish are hatched from eggs produced by brood stock, selected over several years to produce fast growing fish. Many breeding fish are kept in the system, ensuring good genetic diversity in the population. Because the life cycle of the hāpuku is relatively straight forward, with light and temperature providing the cues to spawn, multiple tanks on staggered cycles allow for a consistent supply of eggs. One female can produce 3-4 litres of eggs every 4 days, with each litre containing about 400,000 eggs.  

In the hatchery each tank is supplied with about a litre of eggs, that quickly develop into what resemble translucent mosquito larvae, before becoming fingerlings. Soon after, they are transferred again into one of eight 350,000 litre tanks, each capable of growing 10,000 fish to their 3kg harvest size in under 12 months. 

Over the course of two decades, NIWA has developed its own production systems to alleviate the challenges inherent in aquaculture operations. A particular formulation of highly digestible food had been designed to produce ‘denser’ faeces, making it easier to remove from the water. Another by-product of metabolizing protein is ammonia. This is extracted using colonies of bacteria housed in biofilters with large surface area that convert ammonia to a non-toxic state.  

Carbon dioxide is another waste source that is expelled from the water by pushing large volumes of air through the tanks. Oxygen is added to the recirculated water to keep the fish healthy and stress-free. The equivalent of one tank of water runs through this process every 20 minutes, and 98 percent of the water is recirculated through the system.  

Dr Andrew Forsythe is NIWA’s Chief Scientist for Aquaculture & Biotechnology. He explains that nearly two decades of scientific and market research has been realised in this fully commercial operation at Bream Bay, that is capable of producing up to 600 tonnes of fish each year. And he adds there is plenty of room for growth, with the facility able to supply and support an estimated million juveniles each year - producing 3,000 tonnes of fish in total. This would create about 75 new jobs and a substantial lift in income for the region. 

Discussions have also been had with commercial partners around managing, harvesting, and transporting. Andrew confirms there has been a huge amount of interest from the seafood sector and other investors, as the technology has been developed to be replicated for other species and locations (given ready access to adequate seawater). Work is underway for hāpuku.  

Andrew believes that optimal management of the environment is at the heart of the system. It enables the reduction of parasites and pathogens and optimizes the environmental factors (such as temperature) that deliver the end result – a healthy, high-quality protein. He maintains that with the right approach, aquaculture can be both ecologically sustainable and economically valuable, and offers a way to insulate ourselves against the extreme events that a changing climate is bringing to our world. 

Links: 

https://www.ruraldelivery.net.nz/posts/NIWA-Bream-Bay-Kingfish-Hatchery-2017-04-03-23-56-53Z 

https://niwa.co.nz/