EcoNet - High performance and escape prevention

EcoNet ensures maximum water flow to the fish. This has resulted in best ever production results in large scale salmon farming, such as higher SGR, lower FCR, lower mortality and higher fish harvest quality.
2015 econetSince AKVA group first introduced EcoNet to the salmon industry in 2009, the company has focused substantial resources on comprehensive laboratory and field testing, as well as proper documentation and NS9415;2009 certification. This has been done in close cooperation with the Italian manufacturer, Maccaferri Industrial Group, Sintef in Norway and key customers around the world. Prior to this, fish farmers in Japan have used this proven and unique netting material for more than 20 years. Today, Eco Nets are successfully used in large scale salmon farming by Cermaq Norway, Grieg Seafood Hjaltland (Shetland) and Tassal in Tasmania (called Kikkonet in this market).

Cermaq Norway and AKVA group have cooperated in testing and further development of the EcoNet concept since early 2012 when the first 120m circumference net was installed at Cermaq in Steigen, Northern Norway. In the spring
of 2014 the company ordered EcoNets for a complete salmon farm, using large 160m circumference nets (51m diameter x 34m deep). This was followed by ordering more of the same EcoNets for a second complete salmon farm in April 2015. It is the continued good production results from this testing and full scale production of several fish generations that has resulted in continued use of EcoNets.

Snorre Jonassen, Director at Cermaq Norway AS, confirms the good productions results with EcoNets. We transferred 1,5kg salmon into the EcoNet cage in June 2012 and harvested 6,5kg salmon 7 months later, with a biological FCR (Feed Conversion Rate) of 1,09 and Economical FCR of 1,10. I was uncertain how to handle this net during harvest and lice treatments, but we had no problems and used standard Cermaq net handling procedures. Another advantage with EcoNet is also that we eliminate risk of breaking net meshes during lifting as we don’t need to use steel hooks to pull up the net on the railing.

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More than 250 EcoNets and Kikkonets have now been sold worldwide.

When asked why he thinks they achieved this result Mr. Jonassen replies: It is most likely the good water flow through of the EcoNet that is the main factor. Simply better water quality and environment for the fish. In addition to this we also consider EcoNet as more escape proof than traditional nets.

Trond Severinsen, COO – Export at AKVA group ASA, has been in charge of the company’s EcoNet concept since 2009. He agrees with Mr. Jonassen’s comments. EcoNet is made of PET monofilament (solid twine) that has a very hard and smooth surface.

This results in very low water drag resistance due to low “total wetted surface area” compared to multi-filament (fiber nets). Smooth and hard surface also makes net washing in the sea very fast and efficient.

Customers claim they clean EcoNet twice as fast as regular nets. In addition, the net panels are thermoformed in the “knitting machine” so that the net mesh and net wall remains stiffer without deformation, even in strong currents.

The low water drag resistance allows use of light weight sinkertube (10-15 kg/m compared to 40-70 kg/m). This makes handling the net during harvest, grading, sea lice treatments and similar, easier and safer for the farm crew.

Lastly, EcoNet offers our customers a good opportunity to reduce the risk of fish escapes by using this net technology also for salmon farming. This has resulted in several new “green licenses” being awarded to fish farms in Norway using EcoNets as a main concept for their applications, adds Severinsen.

Around the world, EcoNet has proven very resistant to predator attacks (Grey Seals, Fur Seals, Sharks, Tiger Tooth Fish, Barracuda, Travelli etc.) due to the strong PET monofilament and semi-rigid and tightly stretched net walls. Should damage to the net occur, the semi-rigid structure has proven to have self-closing properties that prevent fish escape. The thermo-formed double twisted PET mesh also
prevents unraveling.

In addition to the minimum requirements of NS9415;2009 (Norwegian Standard for aquaculture equipment), we have also conducted further testing at SINTEF in Norway in order to document additional unique EcoNet material properties. They include high tensile strength, chafe resistance and long lifespan.

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The semi-rigid net structure maximize water flow and oxygen to the fish.

EcoNet is now NS9415 certified to stay in the sea for 14 years. This also eliminates the need for handling or changing nets, and thereby also a considerable escape risk and operating cost. Further design details are being continuously improved in cooperation with our customers, and EcoNet is now becoming a proven net concept also in large scale salmon farming, concludes Severinsen. EcoNet is now available in 3 different hexagonal mesh sizes and PET twine thicknesses:
  • Small: 35mm wide x 43mm high mesh opening / 2,5mm Ø PET thread (used for 150g Atlantic Salmon smolts and up)
  • Large: 45mm wide x 71mm high mesh opening / 3,0mm Ø PET thread 
  • Super Large: 73mm wide x 100mm high mesh opening / 3,5mm Ø PET thread (suitable for predator nets)

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By Trond Severinsen
Chief Operating Officer – Export
AKVA group ASA