Our scientists are developing a prototype mobile aquaculture system - a fish pen that can move around the open ocean based on the needs of the fish and environmental conditions.

Mobility is the vision for the future, with the first stage being a moored prototype fish enclosure in ocean conditions at the top of Aotearoa New Zealand's South Island.

What is open ocean aquaculture?

Open ocean aquaculture involves fish farming in deep ocean waters, several kilometres from shore. This will support the growth of Aotearoa New Zealand’s aquaculture sector, increasing the area available for aquaculture and expanding the species that can be raised in aquaculture systems.

How do the prototype fish pens differ from others already in use?

The prototype fish pen has been designed to be mobile, meaning it can be moved to allow fish to experience optimal water temperatures and conditions year-round. For this pilot project however, the pen will be attached to a swing mooring and be submerged 10-15 metres below the water surface.

The prototype fish pen being trialled will also be smaller compared the commercial aquaculture pens currenly in use.

How do you know the fish pens can handle the open ocean conditions?

Open ocean aquaculture comes with different technological challenges that our scientists have been working to overcome since they began developing this mobile concept in 2016.

For example, scientists at Plant & Food Research have tested the prototype fish pen at exposed mooring sites in Tasman Bay and used scientific modelling conducted with international collaborators to make sure the pen structures are robust enough for a high-energy ocean environment.

How do you know the fish can handle the open ocean conditions?

The fish that will be transferred to the prototype pen from Plant & Food Research’s finfish facility will be salmon and snapper. A major part of the development of the prototype fish pen has been focussing on what the fish need to be at their best in an open ocean farming environment. Plant & Food Research scientists have developed the prototype using their extensive knowledge of salmon and snapper biology, and new knowledge contributed by PhD students, including how these species respond to water temperature as well as water flow. We are confident that these species will perform well in the prototype pen.

The water temperature profile at the trial site means that we will assess snapper performance in the pen during summer months, and Chinook salmon during the winter.

What are the potential effects of the fish pen and aquaculture system on the marine ecosystem?

Effects on the marine ecosystem will be relatively low due to the small scale and short duration of the trials, compared with commercial aquaculture farms. The environment is resilient and there are no sensitive habitats within 2km of the site. Monitoring and adaptive management will be undertaken to ensure any unforeseen impacts are detected and addressed, which were outlined as part of the resource consent conditions allowing the trials to take place.

The main expected impact is uneaten fish feed and fish faeces settling on the seabed: this is estimated to be restricted to within 100m of the fish pens and expected to be of low impact.

Plant & Food Research has management plans and protocols to mitigate other potential impacts, such as:

You can find detailed information in Plant & Food Research’s environmental assessment as part of its application to the Environmental Protection Authority (EPA), available online here.

What species of fish are farmed in Aotearoa New Zealand?

Only one species of fin fish is currently farmed at scale in New Zealand’s marine environment – the King salmon (Chinook salmon).

Breeding native species of fish could diversify existing markets and create a new sector for the export market, supporting future growth of the aquaculture sector.

Plant & Food Research is focused on developing native species, such as snapper, for ocean-based aquaculture; our snapper breeding programme reached a milestone in March 2024 with Government approval for Plant & Food Research to transfer our snapper from tanks at our Nelson Research Centre, to a commercial aquaculture facility in open water. Read the press release

You can find detailed information in Plant & Food Research’s biosecurity, fish health & welfare, and wildlife management plan as part of its application to the Environmental Protection Authority (EPA), available online here.

Where is the trial site?

The site of the aquaculture trial is approximately 3.5 hectares in size, and located within the boundaries of an existing marine farm in Tasman Bay, approximately 6 kilometres to the west of Sauvage Point, D’Urville Island. This site allows the system to be tested in open ocean conditions but is also accessible for the research team.

What will be trialled at the site?

The prototype fish pen, together with a support and monitoring buoy, will be trialled at the site. The fish pen will be submerged 10-15m below the water surface.

As part of the resource consent conditions, only one pen can be trialled at the site at any one time.

What measures are you taking to reduce potential adverse effects?

Plant & Food Research’s mobile aquaculture prototype is designed to be low impact. We have management plans and technology to monitor environmental conditions closely and in real-time. Specific measures include:

You can find detailed information in Plant & Food Research’s biosecurity, fish health & welfare, and wildlife management plan as part of its application to the Environmental Protection Authority (EPA), available online here.

Don't fish farms produce a lot of waste (fish effluent)? How will that affect the environment?

Fish farms can produce waste in the form of fish effluent, but the potential effects from this proposed trial are expected to be minimal for several reasons:

The scale of the trials is very small compared to commercial fish farms. The maximum fish biomass (18,750 kg) and annual feed input (50,000 kg) for these trials is only about 9-12% of what a small commercial salmon farm would produce.

The trials will use efficient feeding regimes to reduce waste. Cameras will monitor the fish feeding behaviour so that we can adjust feed rates to minimise uneaten feed.

The site has moderate water currents and deeper-than-typical depths, which will help spread out deposits over a larger area.

You can find detailed information in Plant & Food Research’s environmental assessment as part of its application to the Environmental Protection Authority (EPA), available online here.

How will you prevent marine animals, like dolphins and birds, getting entangled in the fish pen and other infrastructure?

The risk of entanglement was assessed to be minor due to the nature of the site, the small scale of the trials and mitigation measures such as:

We have consulted with the Department of Conservation and have an agreed protocol in place with them in the highly unlikely event a marine animal becomes entangled.

You can find detailed information in Plant & Food Research’s biosecurity, fish health & welfare, and wildlife management plan as part of its application to the Environmental Protection Authority (EPA), available online here.

Are the fish pens tethered to the seabed and what are the effects of this?

The fish pen is tethered to the seabed, using a three-point, screw anchor mooring system. This system is designed for minimal disruption to the seabed during installation, use and removal.

What are the risks of captive fish escaping or being accidentally released from the pen?

As with all fish farming, there is some risk of fish escaping from the pen and potentially impacting wild populations through competition (i.e. for food) or genetic mixing. Plant & Food Research will mitigate this risk by:

Will there be any impacts on commercial or recreational fishers?

The trial fish pens will be installed off a mooring within the boundaries of an existing marine farm.

Our message for fishers is that that if they are fishing in the waters around D’Urville Island this summer, they might notice a new mooring, together with four special buoys that mark the boundary of the test site. This will be home to the first prototype of Plant & Food Research’s new ocean aquaculture system.

This is our ‘science at work’ and we thank fishers for navigating around the site as they do any other ocean infrastructure.

Who owns the marine farm where the trials will occur?

The marine farm is operated by Wakatū Incorporation.

How long will the trials run for?

We have resource consent to undertake trials for approximately seven years, from 2025.

At the end of the trial, will you remove all the structures and return the site to how it was?

Yes, the mooring and fish pens are able to be removed from the site at the conclusion of the trials, with minimal impact.