Cawthron’s innovative new ‘Shellfish Tower’ structure a practical solution for open ocean farming

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By Milthon Lujan

A recently published study has shown that an innovative new open ocean aquaculture structure is a promising solution for marine farming of shellfish and other species in exposed waters.

Aquaculture researchers at Nelson’s Cawthron Institute worked with a team of international researchers and industry partners to design and test the ‘Shellfish Tower’ structure through an MBIE Endeavour Fund project that began in 2016.

Five years on, a full-scale prototype of the Shellfish Tower has been trialed in partnership with Opotiki’s Whakatohea Mussels and shown great potential as a farming system for mussel spat and oysters, and other species like scallops, lobsters, sponges and tunicates.

The trial also confirmed the structure performs well in the high-energy open ocean environment, tolerating wave heights of over 7m and currents of over 0.8m/s.

With limited space in sheltered coastal areas for farming, environmental pressures like climate change and the desire to diversify aquaculture species, research leader Kevin Heasman of Cawthron Institute said structures that enable offshore farming in challenging high-energy environments are an essential part of aquaculture’s future.

“The Government’s Aquaculture Strategy has set a target of growing revenue to $3b p.a. by 2035 and we believe this is possible, but it will require investment in research and technology to underpin and support expansion,” Kevin Heasman said.

“We want to see marine farmers working in exposed waters around the world empowered with a variety of tools to support different species.

“We chose to collaborate with aquaculture industry partners at Whakatohea Mussels, Wakatu Incorporation and Sanford Ltd. because they are already committed to innovative R&D that will advance New Zealand’s aquaculture industry and they have commercial and operational experience in both inshore and offshore farming that was invaluable in informing the design of the structure.”

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The Shellfish Tower was modelled, tested and refined in partnership with researchers at the Technical University of Braunschweig and Leibniz University in Hannover and the Alfred Wegener Institute in Bremerhaven. This process involved testing a small scale prototype in hi-tech wave flumes and a 3D wave and current basin to see how it responded in a simulated open ocean environment.

Cawthron Institute’s CEO Volker Kuntzsch said the Shellfish Tower is an example of innovative and transformative technology that will help marine farmers take advantage of the opportunities the open ocean represents.

“The Shellfish Tower’s success demonstrates that offshore farming is now developing into an increasingly practical opportunity that will enable the growth of New Zeaand’s aquaculture industry, for shellfish and other species, producing high-quality, sustainable food and creating employment opportunities in coastal regions,” Mr Kuntzsch said.

Max Kennedy, Manager Contestable Investments at MBIE, said the goal of the fund is to support scientific excellence and deliver high economic, environmental and societal impact.

“The Endeavour Fund supports ambitious, transformative research, science and innovation projects that generate new knowledge and create new opportunities, which is why MBIE invested in Cawthron Institute’s open ocean aquaculture farming systems research and development programme,” Max Kennedy said.

“This project in particular has seen Cawthron Institute in Nelson work with some of the world’s leading open ocean engineering and marine farming experts and build strong international relationships that will support future collaboration.”

Reference (open access):
Heasman, Kevin & Scott, Nicholas & Smeaton, Malcolm & Goseberg, Nils & Hildebrandt, Arndt & Vitasovich, Peter & Elliot, Andrew & Mandeno, Michael & Buck, Bela. (2021). –NC-ND license New system design for the cultivation of extractive species at exposed sites – Part 1: System design, deployment and first response to high-energy environments. Applied Ocean Research. 110. 102603.

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Source: Cawthron Institute

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