THE LAST FEW years have seen an increasing interestin offshore fish farming, yet the are are stillquestions that be asked about how genuinely viableproduction can be achieved at offshore locations.According to Norwegian company Global Maritime,which has expertise and experience behind it in theoil and gas sector, there are lessons to be learned andtechnologies that can be adapted for taking fishfarming offshore.

Global Maritime is in the process of transferring itsoffshore expertise to the aquaculture sector with itsinvolvement in the development of an offshoreinstallation for Ocean Farming off the Norwegianisland of Frøya.

Bernt Ege and Karl Strømsem at Global Maritimeare convinced that the new design combines the bestof existing technology and solutions from theNorwegian fish farming industry and the offshore oiland gas sector.

Commenting on the question of whether of notoffshore farming can become commercially viable,they are adamant that this sector has a real future.

“While there are potentially costly engineering andlogistical challenges, from maintenance to feeding toharvesting the fish, and while there are operationalchallenges in running fish farms in harsh offshoreweather conditions, I believe that the answer is yes,”Bernt Ege said.

“I also believe that transferring existing expertisein the offshore oil and gas sector to aquaculture cango a long way towards ensuring that offshore fishfarms become a vital and profitable source of futurefood production.”

“Take oil & gas semi-submersibles, for example,”Karl Strømsem commented. “These are anchoredfloating marine vessels that support activities such asdrilling, production and accommodation. Such vesselsare secured to the seafloor and are designed towithstand the harshest of offshore environments. Thisrequires the latest in structural engineering innovations,including stability and structural strength analyses, risk-based structural assessments, mechanical analysis anddesign and third-party verification. Semi-submersiblesare also intended to have a small footprint to reduceexposure to waves.”

He explained that automation on semi-submersibles is also a key driver, particularly in the lowoil and gas sector price environment, with streamlinedoperations meaning improved profitability. Automationcovers everything from vessel management to controland dynamic positioning systems, and drilling andproduction automation.

“From anchoring and structural design to mooringand automation solutions, the oil and gas sector andsemi-submersibles have much to offer offshore fishfarming in addition to mono hulls and other forms ofshipping.”

Already responsible for designing and supportingsome of the world’s largest floating offshorestructures, Global Maritime Consultancy & Engineeringis now taking its offshore and engineering expertiseinto aquaculture. One such application is an offshorefarming facility which will be located near the islandof Frøya in Norway and is destined to be the world’slargest fish farm offshore Norway. Run by Ocean

Farming, it will focus on salmon and will be apermanently moored semi-submersible structure.

The project has been approved by the NorwegianMinistry of Trade and Fisheries and is set to beoperational later this year. Partners in its developmentinclude the Norwegian Marine Technology ResearchInstitute (MARINTEK), DNV GL, who verified the designwork, and Kongsberg Maritime who delivered powergeneration, automation controls and fish sensors.According to Bernt Ege and Karl Strømsem, GlobalMaritime’s oil and gas industry expertise has alsobeen a key part of the in the facility’s design.

“With the need to have a stable structure withminimal movement during rough weather, as isnecessary in oil and gas as well as in aquaculture,Global Maritime designed a permanent, anchor-fixedstructure. The submerged part of the farm is fixed to

the seabed by eight catenary mooring lines andflotation tanks are placed beneath the seven verticalmain columns for increased support. The design alsoincludes one moveable and two fixed bulkheads.”

The importance of limited wave movements wasalso addressed by the establishing of a small waterplane area in the wave-affected areas of the columns,ensuring minimal movement in harsh conditions.

To ensure large volumes of water to improve fishwelfare, the semi-submersible is operational atdepths between 100 and 300 metres, allowing for awater volume of 250,000 billion cubic metres (bcm).This provides the salmon with the opportunity toswim deep as well as enabling more fish to befarmed and improving the farm’s economics. The farmhas the capacity to raise 1.5 million fish annually.

The facility has been developed in as economicaland sustainable way as possible with limitedmaintenance requirements and highly durablestructural components.

“The life of the structure is estimated at 25 yearsand is designed to survive ship collisions or a once-in-century-years wave conditions. All farming operationsare also managed either on board or remotely,minimising the costs arising from service vessel use,”Bernt Ege said.

Automated spray nozzles clean the nets and thefeeding and harvesting of the fish and removal ofdead fish is integrated into the design. In all cases,heavier manual operations are avoided with a crew ofthree able to manage the whole facility.

“While there may be a higher initial investmentcost, once up and running operational costs foroffshore fish farms are likely to lower in the long-term. Tapping into expertise in oil and gas is playingan important role in achieving this,” he said.

16 www.worldfishing.net March 2017

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Oil & gas technology forworld’s largest offshore farm

ALL ROUTINE DAILY operations can be managed on board the facility without the need for service vessels or other outside equipment

THE SEMI-SUBMERSIBLE is designed to be operational at depths of between 100 and 300m and allows for a water volume of 250,000 billion cubic metres

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