Planet Care

152: Offshore and enclosed fish farm


Due to the micro plastic soup in the world’s oceans, microplastic has entered fish food chain and nobody quite knows how to clean it up. Despite all these environmental and potential human health impacts, most scientists agree that it is not feasible to clean up the plastic in our oceans.


Offshore and enclosed fish farms.

The Norwegian Ministry of Fisheries and Coastal affairs recently decided to award development licenses for aquaculture purposes. The objective is to spur new technology concepts that can ensure sufficient growth whilst also ensuring environmental sustainability.

Since 2013, Mowi and Aquafarm Equipment have tested post smolt production in the semi-closed cage “Neptun” at Skånevik, Western Norway. It is the third generation of the research cage “Neptun”, which is now in use.

The cage is 130 ft. (40 meters) in diameter on the inside, and 413 ft. (126 m) in circumference. The cage is 72 ft. (22 m) deep and holds 5 million gallons (21,000 cubic meters) of water.“Neptun” is designed to produce up to one million smolts. By October 2019, it was ready for the sixth release of fish when 600,000 smolt would enter the cage.

Scaling it up, in 2017, Ocean Farming ASA of Kverva, Norway, collaborated with China’s Wuch ang Shipbuilding Industry Corporation (CSIS) in Qingdao to produce Ocean Farm 1, the world’s first semi-submersible automated offshore fish farm. 223 ft. (68 m) high by 110m², its 66 million gallons (250,000 m³) volume can accommodate water for farming 1.5 million baby salmon. Its moveable bulkhead was built by Malm Orstad.

Ocean Farm 1 is a full-scale pilot facility for testing, learning, research and development. It will be equipped for R&D activities, with particular focus on biological conditions and fish welfare.

Aiming to reduce environmental footprints, improve fish welfare and answer acreage challenges, the learning and new solutions from the project could represent a new era in sustainable seafood production – and is potentially adaptable worldwide. It is located at Frohavet, some 5km off the coast of Central Norway, at the same latitude as Alaska.

In September 2018, the crew on board observed that the seabed mooring under Ocean Farm 1 was leaning. The issue was quickly corrected and measures were taken for capture the escaped fish. Despite this, by January 2019, Ocean Farm I enjoyed a fine harvest. SalMar announced it would take a further step towards open sea farming with the “Smart Fish Farm” development concept with MariCulture AS, in which SalMar has bought a controlling stake in.

The cage is divided into eight zones and is designed to handle waves of up to 100 ft. (30 m) in the open sea. It has a diameter of 525 ft. (160 m) and it can accommodate three million salmon. SalMar aims to establish a deepwater mooring in the Norwegian Sea off the coast of Trøndelag.

In comparison with other types of food, salmon performs well in terms of GHG-emissions. Production of 2.2 lbs (1 kg.) of farmed salmon requires approximately 2.6 lb. (1.2 kg.) of feed, whereas 8 to 17 lbs. (4 – 8 kg.) of feed is required to produce 2.2 lb. (1 kg) of beef. SalMar’s offshore cage can produce approximately 8,000 tons of salmon in 12 to 15 months. This is equivalent to 25,000 bulls. Furthermore, arable land is fast becoming a limited resource. The biggest potential for sustainable growth now lies at sea. (

A second ocean fish farm, financed by Rizhao Wanzefeng Fisheries, is the 115 ft.-tall (35 m), 200 ft. (60m) wide Deep Blue 1 pen, China’s largest offshore salmon farm, also built by Wuchuan Shipbuilding.

It was launched and then towed 130 nautical mi. to the Yellow Sea. It was then stocked with 200,000 smolt salmon. Due to teething problems, less than a year after its launch, it was returned to a port in Weihai, Shandong province where it underwent “regular maintenance”. When it returned to the sea, it had been retrofitted with a large 115 ft (35 m) tower, as tall as an 11-story building.

Some 130,000 fish smolt were then transferred back into the pen, half of them rainbow trout. Deep Blue I is designed to sit on the seabed where the water, at 200-230 ft. (60-70m) deep, is colder than water at the surface, and therefore more suitable for raising salmon.

During its first year, Deep Blue I survived nine typhoons and other harsh conditions during two important seasons, summer and winter. In February 2019, Wuchang Shipbuilding announced plans for a second, possibly even third offshore salmon farm, capable of farming one million salmon.

In the next few years, Rizhao Wanzefeng Fishery Co. will also invest in the construction of a number of “deep blue” series of cages, which will form a “deep-sea salmon farming platform” with workboats, processing vessels and transport vessels.

Discover Solution 153: fish transportation system

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