New Zealand is to construct a prototype offshore shellfish and seaweed farming unit in Tasman Bay after tests conducted by an international research product proved fruitful.

The "Nga Punga o te Moana -- Anchoring Our Open Ocean Future" project -- led by New Zealand's Cawthron Institute and involving Germany's Technische Universitat Braunschweig -- aimed to shift aquaculture from congested coastal regions to exposed ocean areas, some of which are relatively near to shore, but high energy, and others which are further offshore.

Experts from the fields of hydraulic engineering, structural engineering and marine biology are working together to develop innovative, production-efficient technologies that can withstand high-energy environments, said Cawthron.

"The structures that were tested are now being built as full-sized prototypes by Cawthron and will be deployed next year in Tasman Bay in New Zealand as part of a multi-species trial including scallops, oysters and the seaweed Lessonia variegata," it said.

"Producing technology that enables sustainable marine farming in exposed ocean areas has tangible benefits. Many exposed ocean locations are not currently utilized, offering new space for expansion, cleaner and cooler water, less marine animal fouling of farmed structures and an abundant food supply for the farmed species. In addition, aquaculture here has less negative impact on the seabed habitat."

However, these areas are also associated with significantly greater challenges: deeper waters, stronger currents and higher waves place high demands on the stability and resilience of aquaculture facilities.

A crucial aspect is, therefore, the precise determination of the forces acting on the infrastructure in order to avoid oversizing, which leads to high costs for the anchors and their components, as well as undersizing, which would result in the system failing during storms.

In a second series of tests in its wave pool, Braunschweig's scientists recreated the kelp farm on a scale of 1:20. The focus here was on determining the usability of the system under realistic exposed ocean conditions.

The open ocean aquaculture project led by Cawthron is a five-year (2021-2026) national research program funded by the New Zealand government's "Endeavour Fund" with around NZD 11 million ($6.6m), and aims to overcome the challenges to enable the expansion of the aquaculture industry into exposed ocean areas.

Researchers from New Zealand, the US, Ireland, Chile, Norway and Germany are involved.