New ways to deal with an old problem

Net benefi ts

Robots, copper and genetics could all be part of the solution for fouling issues

BY ROBERT OUTRAM

Fouling with algae and crustaceans is a major problem for any piece of kit that has to be left in the sea, and fi sh farmers’ nets are no exception.

The Scottish Sea Farms (SSF) sites at Kishorn and Nevis on the west coast of Scotland have been using two “Flying Net Cleaners” from AKVA. The FNC8s ROVs (remotely operated vehicles) are installed on the service vessels Lady Christine and Solas Na Mara. They are equipped with in-built cameras and sensors that enable operators to see the whole net while cleaning.

Innes Weir, Regional Production Manager for the Mainland with SSF, told the company’s in-house newsletter, The Source: “The FNC8s provide us with several advantages over our manually operated systems. They allow our dedicated net hygiene staff to operate and view the nets from inside the wheelhouse or purpose-built console, improving safety by keeping them out of the elements.

“They provide full visibility and video footage of the net cleaning process and have already assisted in increased containment security on our farms. And they have superior cleaning over our current systems, particularly with the new HDPE SealPro nets, fi tted to prevent predator attacks. They also effectively clean the entire base of the net, and are faster and more reliable than manual systems.”

The ROVs can clean eight cages in a day compared with fi ve under the previous system, SSF says, and each ROV requires only one person to operate it, while the manual system required two people at a time.

SSF notes that younger staff members, raised on console gaming, take very SSF notes that younger staff members, raised on console gaming, take very quickly to the ROV controls.

Another net washing robot, the AutoBoss from Trimara Services, is now Another net washing robot, the AutoBoss from Trimara Services, is now available in Chile following the appointment of aquaculture technology and available in Chile following the appointment of aquaculture technology and services business Grupo Ersil as Trimara’s agent in the region. Grupo Ersil was services business Grupo Ersil as Trimara’s agent in the region. Grupo Ersil was established in 2009 and is based in Puerto Montt, Chile. established in 2009 and is based in Puerto Montt, Chile.

The AutoBoss is a fully automated net washing machine now used by fi n fi sh farms in Canada, USA, Scotland, Norway, New Zealand, and Greece.

Included in the purchase of an AutoBoss is a commissionIncluded in the purchase of an AutoBoss is a commissioning and training package. Operators and local mechanics are trained ing and training package. Operators and local mechanics are trained in daily operations as well as routine servicing operations. Ersil will in daily operations as well as routine servicing operations. Ersil will provide these services in Chile as well as sales and marketing backprovide these services in Chile as well as sales and marketing backup.

Trimara is based in Stirling, Scotland and promotes the AutoBoss in Trimara is based in Stirling, Scotland and promotes the AutoBoss in markets around the world.

Stewart Hawthorn, Director, Trimara Services, says: “The AutoBoss is a Stewart Hawthorn, Director, Trimara Services, says: “The AutoBoss is a fantastic machine. It is designed to be reliable, user-friendly, and fantastic machine. It is designed to be reliable, user-friendly, and independent. Trimara provides excellence in commissioning, independent. Trimara provides excellence in commissioning, training, and on-going post-sales support. We want to ensure training, and on-going post-sales support. We want to ensure that our AutoBoss customers in Chile will get the same that our AutoBoss customers in Chile will get the same great support that we deliver in other parts of the world. great support that we deliver in other parts of the world. Our new partner, Ersil, is the perfect fi t.”

As well as on-site washing, nets still require a thorough clean As well as on-site washing, nets still require a thorough clean to get rid of fouling at the end of the production cycle. Norto get rid of fouling at the end of the production cycle. Norway-based Mørenot, which produces nets and moorings for the aquaculway-based Mørenot, which produces nets and moorings for the aquaculture sector, also provides an onshore net cleaning service. ture sector, also provides an onshore net cleaning service.

Mørenot has a net cleaning facility on Shetland and another in the Western Mørenot has a net cleaning facility on Shetland and another in the Western Isles, servicing customers such as Mowi, Scottish Sea Farms and Grieg. Isles, servicing customers such as Mowi, Scottish Sea Farms and Grieg.

Right: Stewart Hawthorn Below: The AutoBoss Opposite from top: Sco� sh Sea Farms, Solas Na Mara; The AutoBoss washing automa� cally

David Goodlad, Managing Director, Scotland with Mørenot, says: “Location is key. Mørenot is the only local service provider with its own dedicated piers, which cuts down on time and on the need for road haulage, reducing our carbon footprint.” Customers have access to the Aquacom module, NETS, free of charge. Integrated with the company’s internal systems, this app provides a full overview of the nets’ conditions throughout their whole lifespan. It can track their whole lifespan. It can track every piece of equipment, providing alerts every piece of equipment, providing alerts when inspection or replacement is due, and it when inspection or replacement is due, and it can also automatically book in nets for can also automatically book in nets for cleaning when the customer is ready, cleaning when the customer is ready, saving time. saving time. But can fouling be reduced in But can fouling be reduced in the fi rst place, making cleaning the fi rst place, making cleaning easier? Copper has long been used easier? Copper has long been used as an antifouling agent for vessels and as an antifouling agent for vessels and nets. The introduction of copper nets. The introduction of copper bottomed ships, which were faster and bottomed ships, which were faster and did not need to return to port frequently did not need to return to port frequently for cleaning, was an early advantage for for cleaning, was an early advantage for

Britain’s Royal Navy in the days of sail. Britain’s Royal Navy in the days of sail.

One solution has been to use One solution has been to use copper-based antifouling paint, but this tends copper-based antifouling paint, but this tends to chip off and sink, with copper residue to chip off and sink, with copper residue drifting to the seabed, potentially harming benthic drifting to the seabed, potentially harming benthic organisms. organisms.

Net maker Garware Technical Fibres has come Net maker Garware Technical Fibres has come up with a copper composite yarn, V2, which comup with a copper composite yarn, V2, which combines high density polythene (HDPE) with metallic bines high density polythene (HDPE) with metallic copper. This allows the slow release of copper ions, copper. This allows the slow release of copper ions, creating added resistance to biofouling. creating added resistance to biofouling.

“Farmers were able to reduce cleaning frequency by up to 50%”

Garware says that trials during 2019-20 showed that farmers were able to reduce cleaning frequency by up to 50%.

NetKem’s Netwax Greenline E5 also uses copper – copper oxide in this case – to help nets resist fouling and UV damage. It is even certifi ed for use at organic farms.

Meanwhile, research carried out by Norway’s SINTEF Ocean and the Cawthron Institute in New Zealand (Effi cacy testing of novel antifouling coatings for pen nets in aquaculture, Nina Bloecher & Oliver Floer, March 2020) put various alternatives to copper coatings to the test. The study compared the effi cacy of six novel antifouling coatings for fi sh farm nets (two with reduced copper content, three with alternative biocides and one biocide-free coating) against a popular commercial copper coating and uncoated samples.

The performance of one of the new coatings with lower copper content was similar to the commercial copper control while the rest were colonised by biofouling faster and/or at higher abundances. However, none of the tested products were able to prevent biofouling entirely, underlining the importance of the search for alternative and improved antifouling technologies, the researchers say.

More radically, a team at New York University’s Abu Dhabi associate has suggested that genetics could provide an answer. Their study (GPCR Genes as Activators of Surface Colonization Pathways in a Model Marine Diatom, Kourosh Salehi-Ashtiani and Weiqi Fu, NYU Abu Dhabi , August 2020) looked at the genes which signal changes in morphology (shape) in diatoms, microscopic algae which play a major part in biofouling. By introducing changes in the diatoms’ genetic makeup, the scientists suggest, the algae could be induced not to bond with surfaces like nets.

In the meantime, however, net cleaning looks like a chore which will be with the industry for some time to come. FF

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