ABSTRACT
A new net cage system for breeding pelagic and flatfish species is developed at Marintek under the Sintef Group’s Strategic Technology Program — Aquaculture..
The concept differs basically from traditional cage systems. The TLC-cage consists of two modules, a vertically moored mooring module and a net pen module. The “rigid” part of the net pen is located at the bottom where the wave motion is small, and the flexibility of the net pen is located at the top. The closed net pen is designed to be completely submerged during a storm condition. Due to the submersion, the forces on the system from wind, waves and current will reach an upper limit. An increase in the current velocity will cause a further submersion of the net pen giving less wave induced forces on the cage. Model tests has verified that this principle gives a considerable reduction in the loads. The cage may be used on deeper and more exposed areas than traditional cage systems. The mooring system requires far less bottom area than conventional catenary moored cages.
The main biologic advantage of the system is that the net pen is not lifted towards the wave surface zone during extreme weather condition which normally cause stress on the fish.
A special version of the cage is designed for breeding flatfish species. Artificial bottoms are installed inside the TLC for storing flatfish species such as halibut. The mooring system ensures that the artificial bottoms always will remain in an horizontal position. This is important in order to avoid hydrodynamic lift forces on the bottom and the fish.
