Offshore aquaculture, development of technology for offshore sea farming (38925)

Project Details


The Danish sea territory spans 105,000 square kilometers of relatively shallow water with salinities ranging from brackish to fully oceanic. The present Danish sea farms are located in the least exposed regions in the Danish fjords and sounds. Environmental constraints are limiting production increase, and new locations in the coastal zone are rarely allocated. The shortage of suitable inshore sites emphasizes the urge to move to more exposed sites where benthic impacts are reduced or eliminated.

The offshore areas of the Danish sea territory holds vast areas with no or negligible activities apart from capture fishery. Venturing into these areas with aquaculture opens a major window of opportunity, but is also a serious challenge being too great for a single company to lift.

The overall purpose of developing the offshore production system is to create the technical foundation for “farming the ocean”. In other words to make it possible to locate cage culture facilities in areas now not considered suitable for fish farming because of their exposure to the physical forces of the open sea.

The project developed and tested different cage designs, anchoring and mooring systems and serviceability for offshore production. Submersible systems were found to be too unreliable in their operation as well as being difficult to maintain and service.

The project found that a modification of conventionally designed cages constructed in more heavy duty materials were well suited for offshore production. Test production of trout showed that even in locations where significant wave heights exceed 3 meters, fish production was possible. Excess water currents were found to negatively influence production efficiency, resulting in poorer feed conversion, and increased nutrient emission from fish production. Similarly, increasing salinity was found to have a major negative influence on feed utilization.

Physiologically, it was found to be possible to submerge fish for periods of up to 2 weeks without adverse effects on fish. The project concludes that offshore farming is possible, but also that environmental impact from fish farming and production efficiency are influenced by the physical environment that fish are farmed in, which should be taken into account during site selection.

The project was coordinated by Hvalpsund Net, Denmark and funded by the Danish Ministry of Food, Agriculture and Fisheries and the European Fisheries Fund (EFF).

Research area: Aquaculture
Effective start/end date01/01/201101/10/2015