Difficulty in treating fish in sea cages
The main advantage of this aquaculture model is that it eliminates the need for artificial water exchange and water treatment steps. On the downside, high stock densities increase the risk of disease, infections and parasites (such as sea lice) in caged fish populations. Treatment with medication and parasite repellents is not only technically very complicated, but also stressful for the fish. To administer drugs, sea cages have to be sealed with foil – which cuts off the water flow and oxygen supply. Additional oxygenation is thus essential during these medical or de-licing treatments.
Environmental challenges can also create a need for supplemental oxygen in sea cages. Warm water, stagnant current or other unfavourable environmental conditions such as algal growth can result in temporary oxygen insufficiency. A rise in temperatures reduces oxygen solubility in water, for instance. This can compromise fish health and increase mortality.