Aquaculture: Snapper trialled in Tasman Bay open ocean farming system

Snapper are being trialled in a new open ocean aquaculture farming system developed by Plant & Food Research scientists. Photo / Plant & Food Research

By Samantha Gee of RNZ

Snapper are being trialled in a new open ocean aquaculture farming system in Tasman Bay.

It is the first time a new finfish species has been trialled off the New Zealand coastline, with Chinook salmon the only fish currently raised commercially in sea-based aquaculture.

The prototype is the work of Nelson-based Plant & Food Research scientists, who have developed a mobile fish farm that’s based in the open ocean.

Senior scientist Suzy Black, who leads the programme, said the aim was to create a low-impact, aquaculture system that is designed around the needs of the fish.

“Over the last 10 years, we’ve developed a concept around a mobile aquaculture system that’s submerged below the surface and can be moved around.”

The project was granted consent last July after consideration by an independent panel under the now-repealed Covid-19 Recovery (Fast-track Consenting) Act.

The trial system is on a swing mooring, near Rangitoto ki te Tonga, D’Urville Island, at the top of the South Island.

It sits 10-15 metres below the surface, and moves with the tide.

Black said it was a stepping stone toward a fully mobile version.

“That’s the vision in the future, so the fish can be transported to the best water temperature that they can grow in and the best water conditions, year-round.”

Black said around 2000 snapper, or tāmure, were transferred to the 500 cubic metre enclosure in April, while the water was warm enough for the first trial, with a focus on how they grow and cope in the pen.

The snapper will be replaced with Chinook salmon for a longer trial over the winter months.

The system is monitored remotely, with scientists able to feed and check on the fish from land through cameras within the pen, alongside visiting the farm at least once a week.

Dr Suzy Black leads the Whakapōhewa ki ahumoana – Reimagining Aquaculture programme for Plant & Food Research in Nelson. Photo / RNZ, Samantha Gee

“We need to know that they are content, healthy, that they are being fed and are growing well, and that the water flowing through the pen is at a comfortable flow rate for them.

“The 30-year vision is to have a fully mobile system that is controlled from land, and you don’t have people out there, its tootling around in the ocean, the fish are growing their best, living their best lives in a system that’s providing everything for them, having the best temperatures, best flow rates, best water quality, that we can control from land.”

The farm was roughly six kilometres from shore, in an area subject to intense weather.

A bird's eye view of Plant & Food Research's open ocean aquaculture prototype near Rangitoto ki te Tonga, D’Urville Island at the top of the South Island. Photo / Plant & Food Research

“The hydrodynamics out there are pretty substantial, the wave height can be considerable, and the currents can be considerable as well.

“The storm systems like we’re experiencing at the moment, it’s giving it a real test, but it’s holding up really, really well.”

She said there was a Māori co-innovation group within the research programme, and the scientists worked closely with the eight iwi of Te Tauihu.

The snapper transferred into the pen were about 16 months old and weighed about 200 grams.

Snapper being transferred into the prototype of a mobile open ocean aquaculture system near Rangitoto ki te Tonga, D’Urville Island at the top of the South Island. Photo / Plant & Food Research

They were cultured from wild broodstock caught in Tasman Bay at Plant and Food Research’s Port Nelson facility.

Black said that had been important to iwi.

“This is a prototype system, so if something happens where it breaks up and the fish are released, they wanted fish that were going out that were close to wild type as possible.”

Black said a huge amount of work had gone into developing the system with a focus on animal welfare, with the trial farm different from open ocean structures seen in other parts of the world.

Plant & Food Research scientists have deployed their first prototype of a mobile open ocean aquaculture system near Rangitoto ki te Tonga, D’Urville Island, at the top of the South Island. Photo / Plant & Food Research

“We’ve taken a soft-engineered approach to this system, we see it as being particularly scalable, and for the infrastructure cost being a lot lower than some of those heavily engineered systems around the world.”

Black said there was a lot of work to be done before the mobile open ocean farm was commercially viable, but she was hopeful of seeing pilot-scale trials happening in the next 10 years.

Oceans and Fisheries Minister Shane Jones launched the New Zealand Aquaculture Development Plan 2025-2030, with the aim of growing the industry’s revenue to $3 billion a year by 2035.

Black said the prototype was at the technical feasibility stage and they needed to prove it could be scaled up, was reliable and could withstand wear and tear for a number of years, but ultimately that it could contribute towards generating that revenue.

“We believe that this type of scalable, lower-cost approach to open ocean aquaculture could become a real opportunity, not just for the big players in aquaculture here in New Zealand, but potentially for new players coming in.”

The project has been funded by the Ministry of Business, Innovation and Employment’s Endeavour Fund.

- RNZ