Offshore farming
Proven submersible pen technology could be adapted for salmon
INNOVASEA Systems may be primarily focused on open ocean submersible farms for growing warm water finfish, but the company is also interested in developing its technology for the salmon market. The Boston based company’s Langley Gace, taking part in a Sustainable Aquaculture Technologies session, said their new Evolution Pen, based on traditional surface pens, fits into a container equipped with buoyancy control.
This means it can go up and down, ‘very slowly if needed’, to deal with fish with swim bladders, such as salmonids.
Gace said that the system isn’t ready to be used for salmon yet- but it is in pre-production testing in La Paz, Mexico.
Meanwhile, the company’s SeaStation submersible pen is beginning a trial off the coast of New Hampshire with trout.
‘The theory is that sea lice are obviously more attracted to the surface. What we’re going to trial is keep those pens down for two weeks and then at night – when sea lice are possibly fewer in number and less dense – bring up the pens for 40 minutes.’
Gace said that the first fish the company ever put in one of its pens, in 1996, were salmon.
‘We didn’t have a permit for the pens and we had to sink the cage when the federal inspector was coming.
‘We hadn’t sunk it before but we did, the guy came and there was no pen, and then we decided why don’t we just leave it?
‘We didn’t really have the economics to take it to the salmon industry, we were focusing on warm water, but we’re excited about this project. We’ll let you know!’
Innovasea – formed in 2015 by a merger between Ocean Spar (where Gace worked for 23 years) and Ocean Farm Technologies- had a significant cash injection when it joined the Cuna del Mar group in 2017.
This, said Gace, ‘greatly improved’ the research and development division, which aims to advance aquaculture operations in the open ocean using fully integrated fish farming platforms.
‘There’s not much room for growth at conventional sites so we see opportunities in the open ocean, he added, making the distinction between ‘open ocean’ and ‘offshore’.
‘Whether 600m or 12km [offshore], they both have a lot of energy which is why we like to say open ocean rather than offshore.’
The company’s submersible pen technology, marketed as SeaStation, is now operational across the world, farming several different species at different depths and different distances from the shore – and in often hostile conditions.
Some 2km off the island of Jeju in South Korea, northern Pacific bluefin tuna is farmed in submerged pens, in an ‘almost commercially viable’ operation.
Jeju is in ‘typhoon alley’ and the last one recorded 9m waves; the pens were fine and the tuna was fine, said Gace.
Meanwhile, 600m offshore in Hawaii, once a month the winds pick up, and the farm still has to operate, with most products going to restaurants Las Vegas, San Francisco or Los Angeles, ‘so they have to be able to do their operations’.
At another location, in the Bahamas, Hurricane Frances passed by the submerged farm and they harvested two weeks later.
And in Miramar, Panama, the cobia farm is 12km offshore and subjected to trade winds. Its 22 pens are submerged 90 per cent of the time.
The Innovasea SeaStation pen design is based on two large steel structures: the spar and the rim, which provides a structure for the netting, typically copper alloy wherever waters are shark infested.
The system provides better containment, said Innovasea in its brochure, and its tensioned nets contribute to the consistent delivery of oxygen around the clock, and the lack of churning prevents the fish from being tossed about by waves
The spar, essentially the central pipe and key structural component of the pen, not only controls the buoyancy of the structure but also contributes to its stability.
Because the pens stay submerged throughout most of the grow-out period, traditional feeding methods have been replaced by an underwater feeder, which distributes pellets through the equiv
alent of a soaker hose, developed by the Innovasea team.
‘It sounded easy but the holes are a special shape and it looks like a Christmas tree,’ said Gace.
‘Now the challenge is to factor in currents and maximise the time the pellets are in the cage – there is still work to be done.’
Feeding is controlled by monitoring fish behaviour with high-resolution cameras. Gace said the cameras were developed with the cost to the farmer in mind.
‘We saw there were two types of cameras, the ones that would last 100 years that are meant for North Sea oil that go to 900m, and are cost prohibitive, and then the ones you would almost order on Amazon.com and the cables break afterwards.
‘We hired an R&D team to make a camera that was just good enough for what you need.’
By keeping down the cost, farmers can afford to install up to six cameras in each pen.
A network of sensors provides real-time monitoring and data analysis of environmental conditions and other factors, such as current and waves, dissolved oxygen, salinity, temperature, depth, rope tension, and biomass.
Gace said their biomass estimation can count a cage full of 200,000 to 300,000 fish with about 95 to 97 per cent accuracy ‘in good clear Caribbean water’, although not yet in turbulent water.
He said they cannot yet identify individual fish, but ‘I think ultimately we will do it’.
All the data is transmitted acoustically to a communication buoy and then wirelessly over a mobile phone network to the internet.
Gace said he could look at any cage and see how deep it is and whether it’s tilting, and set text alerts to the farm manager.
The pens also include a mortality containment and removal system, from which fish are vacuum airlifted out.
The learning curve in open ocean farming can be steep and Gace said clients are also offered business advice, in a three-phase approach:
• Phase one – demonstrate site viability, costs, processes and market demand. ‘No matter how well the species is known or how well trained your staff are, they are going to learn things that you don’t want to do on a large farm,’ said Gace.
• Phase two- prove the scalability of the farm up to 1,000 tonnes, and the market.
• Phase three- provide volume and profitability, ‘leverage everything you’ve learned and produce some commercial levels of fish’.
There’s not much room for growth at conventional sites so we see opportunities in the open ocean”