The blue frontier

In the autumn of 2017, three powerful tugs towed the world’s first open ocean net pen into position off the coast of central Norway. Christened Ocean Farm 1, it resembled something more like a semisubmersible fortress than an aquaculture facility, comprising a vast circular rig 68 metres high by 110 metres in diameter.

Launched by Norwegian aquaculture giant SalMar as a pilot facility, Ocean Farm 1 is a clear signal that aquaculture is set to move into deeper waters. Already, SalMar has sought permission to deploy a bigger and better successor facility, capable of producing up to three million salmon a year.

A 2021 RaboResearch report (A Deep Dive into Offshore Aquaculture), described taking aquaculture out to sea as a “logical solution” for countries such as Norway, where there’s a constraint on new permits to farm in the fjords, and China, which suffers from a dearth of suitable coastal sites. But the development of open ocean aquaculture (OOA) is likely to be a global phenomenon given world population growth and the rising demand for seafood, the effects of climate change, and the increasingly congested and contested nature of coastal space.

The North Sea is central to Europe’s exploration of open ocean aquaculture. Norway, the world’s second largest exporter of fish and seafood, is taking a heavy engineering approach to farming salmon in that more dynamic ocean setting, drawing in part on decades of experience and wealth built up by its offshore oil industry.

The Netherlands is heading down a different route. A 2016 feasibility study by Wageningen University Marine Research poured cold water on the prospect of intensive fish farming in the Dutch North Sea, but suggested there was potential for seaweed and shellfish, particularly when tied to other offshore developments – mussel production alongside ocean wind farms, for instance.

“Offshore aquaculture development is considered a viable option, although the North Sea is a technical challenge owing to its dynamic conditions,” remarks one of the report’s authors, Marnix Poelman.

The first pilots of mussel culturing will begin next year in less exposed but still challenging waters. Marnix says it’s expected that The Netherlands could grow its mussel production by 50%. But he adds a caveat: “This potential will only be feasible by implementing seaweed and shellfish as an integral part of the food system.”

Closer to home, Australia is taking a similarly integrated approach to its early OOA work. The Tasmanian-based Blue Economy Cooperative Research Centre (BECRC) brings together 40 research partners from various countries, including New Zealand, and draws on expertise that runs the gamut from maritime engineering to renewable energy to aquaculture.

Like the Dutch, the Australians, who have the world’s third largest exclusive economic zone (EEZ), are looking for ways to marry the development of offshore aquaculture with a transition from fossil fuels – specifically, incorporating something like salmon farming alongside offshore infrastructure deployed to harvest wind and ocean energy and convert it to green hydrogen.

Professor Chris Carter leads the BECRC’s Seafood and Marine Products Programme. He cites Tasmanian salmon farming as a key part of future offshore aquaculture, but says there are good prospects for oysters, seaweed and mussels, along with various other high value species in South Australia, West Australia and Queensland.

“The BECRC is particularly interested in aquaculture systems for different regions, temperate to tropical, farming multiple aquaculture species together and integrated with other offshore industry,” he says, adding that the benefits of heading into deeper water include being somewhat more insulated from the effects of climate change, and being able to farm on a far greater scale.

There are challenges, naturally. “Structures will be subject to a whole set of hydrodynamic forces. Do you modify existing technology or is it more about a total rethink and new systems? You’ll need to limit the time people would spend out there, too, with safety being critical. And because these structures will be more distant, there are also challenges around transport. That leads to questions about the use of renewable energy sources – in the case of the Blue Economy CRC, hydrogen vessels are being discussed.”

“There are also a whole series of technical questions about growing animals in these sites, where there will be quite challenging hydrodynamic conditions, maybe greater current speeds and storm events, as well as biosecurity issues with different pathogens present. Biofouling is another issue. How do we manage that, and what are the implications?”

“So it’s definitely early days, but of course that means there is plenty of opportunity, too. For aquaculture, our opportunity is around supplying a range of high quality seafoods of high nutritional value and with transparent sustainability credentials,” says Carter.

In New Zealand, where the Government’s goal is for aquaculture to be a $3 billion industry by 2035 and where we enjoy the advantage of a massive Exclusive Economic Zone (EEZ), a number of entities have irons in the fire. New Zealand King Salmon has applied for resource consent to place its ‘Blue Endeavour’ farm north of Cape Lambert to take advantage of Cook Strait’s cool temperatures, high flow and deep water. Sanford has sought consent to farm salmon in open ocean at the south-east end of Foveaux Strait, and Ngāi Tahu Seafood has done the same for a deepwater site off Stewart Island/Rakiura.

Behind the scenes, the Cawthron Institute is doing valuable research. In early 2021, the Nelson-based organisation, in collaboration with overseas researchers and New Zealand industry partners, successfully trialled a full-scale prototype ‘Shellfish Tower’, designed to grow mussel spat, oysters and other species in exposed waters. Plant & Food Research is also heavily involved in developing the science that will inform the evolution of offshore aquaculture in this country.

Dr Damian Moran, who leads the Plant & Food Research Ngā Tai Hōhonu Open Ocean Aquaculture research direction, says the same factors driving the development of OOA overseas are in play here. The Marlborough Sounds, for instance, hub of our lucrative salmon industry, has limited scope for any expansion. However, New Zealand seems likely to take a different approach to OOA from those of some other nations. We don’t have the oil money or infrastructure of Norway, for instance, and potential investors here probably won’t have the kind of capital needed for that heavy industrial approach.

Moran says Plant & Food Research is looking at the potential to adapt conventional sea pen technology from overseas to the New Zealand setting.

“Any fish farm will use services from other marine engineering operators. We might build our finfish farming around mussel farming logistics and services, for instance. We already have some open water mussel farming ventures, so can we tap into that.”

Another line of enquiry is mobile oceanic farms. In collaboration with scientists at other New Zealand and overseas research organisations, Plant & Food Research is two years into a five-year proof-of-concept programme to develop a working prototype, with the goal of growing Chinook salmon and tāmure/snapper in 1000 cubic metre moored enclosures in year five. Programme leader Dr Suzy Black says it’s a very different approach from that seen in Norway and elsewhere. “We took the attitude of working with the environment rather than try to build things that would stand up against it.”

Mobility offers the opportunity to get out of the way of devastating one-off storm events – a bit like a ship taking shelter behind an island. But the advantages go further. “If you’re mobile, you can move to places where there are the best temperatures for growth and the best water quality. You can move the animals so they’re in optimal conditions year-round.”

What are the challenges? “This is an aquaculture system that’s a long way from business as usual. If you’re several kilometres offshore, just being able to access your fish and general operations are really challenging. On the engineering side, can the materials withstand the forces in the open ocean? And then there’s monitoring your fish: if you don’t have people on a farm, how do you measure how the fish are growing? Are they happy? Are there predators out there?”

Plant & Food Research is developing ways of measuring performance remotely, using cameras and cutting-edge computing to distil useful data. A group is also working on computer vision analysis to track individual fish – using the fingerprint-like spot patterning of tāmure/snapper, for instance.

“You can get much more information about how a population is doing if you can track individuals,” remarks Moran, who says that Plant & Food Research is also investigating ways to deal with biofouling of offshore infrastructures, with potential solutions including the use of herbivorous service fish and single-use harvestable nets.

What fish will be farmed? In New Zealand, Chinook salmon will always be first cab off the rank, with species such as tāmure/snapper, haku/kingfish and araara/trevally likely candidates for warmer North Island waters. “We’re very much about fish-centric design – what does the fish need to be at its best? That’s really important to us,” says Black.

“We’ve got a PhD student looking at the flows in which tāmure/snapper grow best, the temperatures they prefer and whether they match optimum temperature for growth. We also have a PhD student in The Netherlands looking at similar things for Atlantic salmon.”

The question of aquafeeds also looms large. New Zealand salmon farming relies on imported dry pellets. But as Moran notes, the industry’s sustainability credentials will ultimately be determined by what our fish are fed.

“Eventually, we want to be producing fish that are not just ‘made in’ but ‘made of’ New Zealand,” he says. “So we have to gain control of the bottom of the food pyramid and design and build that ourselves. Technically, that’s difficult because it encompasses a huge range of sizes and types – we’ve got to provide everything from dust-sized live prey up to adult diets – and because these fish are carnivores they require large amounts of fat and protein.”

Plant & Food Research is exploring high quality diets for larvae, and, at the other end of the spectrum, investigating novel sources of protein for adult fish, such as insects, and even lucerne, rye grass and other crops.

Whatever particular shape it takes, moving aquaculture into deeper waters would seem to be inevitable. “In the future,” predicts Moran, “many of the fish we eat will in one way or another be reared.”