FISH FARMING TECHNOLOGYA Breath of Fresh Air in Fish Farming

The Food and Agriculture Organisation, a United Nations agency, has recently stressed the importance of fish farming, noting its place as the most sustainable and fastest growing food sub-sector in the world. The organisation stated that fish provide the world with 17 percent of its animal protein and emphasised the importance of fish farming as a global trade.

However, with increased fish farming comes more responsibility from operators to ensure that their farms are maintaining the best possible fish growing conditions; including appropriate nutrition, prevention of disease and maintaining a healthy water environment.

The importance of healthy waterThe most important factor for achieving healthy fish is to have healthy water. Therefore, controlling the

concentration of oxygen dissolved in water is crucial in aquaculture. Maintaining the right level of oxygen in water improves utilisation of feed, reduces fish mortality and reduces the need for vaccination and antibiotics.

This is particularly important in sea cages. Though some have sufficient oxygen levels from surrounding seawater, there are instances where this is not the case – particularly in locations experiencing rising water temperatures that contain low levels of oxygen. As there is lower solubility of oxygen at higher water temperatures, this situation becomes more critical during summer months than in winter.

Linde, the world’s largest industrial gases and gases engineering company has a long history of working in the area of food security to give food processors and consumers the reassurance that the food they eat is fresh, authentic and sustainable. The company has been supporting fish farmers through its SOLVOX®

In the past 50 years, the global demand

for fish products has doubled, and more

than 45 percent of the world’s seafood today

now comes not from wild catches, but from

either land-based or offshore fish farms. To

meet this rising demand for seafood worldwide,

more fish have to be raised in fish farms,

and aquaculture is an essential link in the

agricultural chain.

by Stefan Dullstein & Hans Joerg Meissner, Linde

50 | March | April 2016 - International Aquafeed

range of products, which comprises a variety of oxygen dissolution and distribution systems, which offer a comprehensive range of oxygen supply modes.

Late last year, the company introduced the latest in the SOLVOX® family – SOLVOX® DropIn – which was designed specifically to meet the need for oxygenation in sea cages.

DropIn: A New Way of Delivering OxygenRepresenting an innovative and effective new way of

improving the delivery of oxygen into fish farming sea cages, the pioneering “DropIn” technology was originally developed for use in improving oxygenation during sea lice treatment. It now also can also be used in sea cages which experience unhealthy water conditions due to poor oxygen levels or where supplementary oxygen is needed, including in harvesting tanks.

The product was designed to be compact and lightweight and highly portable, eliminating the need to drag perforated hoses across cage floors. It comprises an electric pump plus a patented oxygen dissolver and distribution system featuring a venturi nozzle. SOLVOX® DropIn distributes oxygen evenly across a wide radius, delivering it in a pinwheel form, which makes for more homogenous oxygen throughout the cage.

The innovative design represents a break-through in oxygen delivery and is the first of its kind on the market. It provides 50kg of oxygen in the water at 2.2 kilowatts per hour. Typically for the same amount, wastewater treatment will use more than ten kilowatts per hour, which represents a considerable step forward in terms of energy savings.

FISH FARMING TECHNOLOGY

left hand page: The Sovlox DropIn aerator in action

right hand page: The Solvox DropIn aerator

International Aquafeed - March | April 2016 | 51

Mitigating Sea Lice Sea lice are parasites well known to the aquaculture

industry for posing a significant threat to fish farmers. They can compromise the health of fish, and damage their hosts’ skin through feeding, causing lesions and infections through viruses and bacteria. Though they occur naturally in the marine environment, sea lice can represent a particular issue among farmed fish where a more concentrated population means that infestations can spread quickly.

If a sea lice concentration reaches above a certain threshold, fish farmers need to apply treatments. In sea cages, these can only be applied once the cages have been completely wrapped in foil to maintain the necessary concentration of delousing chemicals within the water. However, as the foil cuts off new oxygen supply from outside the cage, a supplementary oxygen supply is needed; this has traditionally been done by using a series of perforated hoses, which have to be dragged over the cages and then lowered onto the cage floors.

Although this is a labour-intensive and time-consuming process, it does not always deliver optimum distribution of oxygen. SOLVOX® DropIn was designed to overcome the operational and effectiveness issues involved with more traditional methods of de-lousing.

ApplicationThe most outstanding aspect of the technology is its

method of application; as it was specifically designed to deliver ease of operation when supplementing oxygen to sea cages.

Using a small crane, SOLVOX® DropIn can be easily

lowered to a desired water depth. The oxygenation unit works by sucking water into the lower part of the unit and mixing it with oxygen. The oxygenated water is then distributed throughout the cage through four nozzles situated at the top. The microbubbles created have a low rising velocity so extends the bubble residence time in the water.

Combined with the large surface-to-volume ratio, this increases the efficiency of the oxygen dissolution, even at low pressures. It has also been observed that this much less disruptive method of delivering increased oxygen has resulted in calmer fish behaviour during the delousing treatment.

The technology is supplied in two delivery options, with one option featuring SOLVOX® DropIn as a standalone unit, and the other comprising of not only just the unit itself but in conjunction with a “Twin Kit” with additional operational accessories including starter box, dosing panel, hose and power cable.

The Twin Kit is ideal for short-term oxygenation and de-lousing treatment that requires installation and quick removal, reducing laborious handling, while the standalone unit makes sense for continuous oxygenation where repetitive installation and removal of the unit is not required.

What’s Next for DropInSince its launch in autumn 2015, SOLVOX® DropIn has

been very well received by the fish farming market and is currently in operation in fish farms in Australia and Norway. During trials, customers provided feedback that SOLVOX® DropIn operated at high levels of efficiency and they experienced up to 40 percent less oxygen usage as compared to existing oxygenation systems utilised. The technology has also recently won a coveted innovation award at the Industriens Motemesse show in Norway.

It is expected that the technology will be rolled out to other key fish farming geographies including New Zealand, Scotland, Chile and Canada this year. Opening market potential and providing the world with more protein, aquaculture will be a growing trend, and SOLVOX® DropIn is designed to enable this going into the future.

As with many other areas of industrial gases development, innovation involving digitalisation and data analysis will be key. Linde is already well set on course to developing more intelligent, ‘smart’ technologies in the area of aquaculture which will serve significantly beneficial to fish farming operations in terms of productivity.

Linde Innovation Centre for Aquaculture Linde undertakes the research and development of all its aquaculture technology at its pioneering Innovation Centre in Ålesund, Norway. With its highly equipped laboratories demonstration tanks, the Centre allows aquaculture technologists to observe how the latest oxygenation technologies impact farmed fish development.

Since its opening in 2012 Linde has introduced the capability to run warm water trials to understand and assess the performance of its technology in high temperature water environments inhabited by more tropical species. Additionally, they have recently installed an external floating dock where technology trials – including SOLVOX® DropIn - can be performed in the surrounding fjord.

image: The Solvox innovation

centre, Norway

FISH FARMING TECHNOLOGY

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