Introduction
In traditional sea-based salmon farms, fish is vulnerable to sea lice, predators and various diseases, to mention a few. The current open-pen solutions are not possible to grow further in many countries due to these issues. Land-based aquaculture solves many of these challenges as well as offering other benefits to the fish and environment, but at the same time new risks are present.
Challenge 1: High capex need
For land-based aquaculture, there is undoubtedly a much higher capex demand than sea-based alternatives. To ensure that the project is profitable, it is required to utilize the production capacity optimal. The solution is to design the system to be flexible, allowing fish to be moved from any tank in the system, split on size, and moved back to any two tanks in the farm – and at the same time minimize the required piping.
Challenge 2: Gentle fish-handling solutions
Handling the fish as it grows larger is increasingly complex. Pumping a full-grown salmon is much more challenging than a smolt, making technology from traditional smolt farms not suitable for the larger fish. The solution is to learn from the wellboat industry (live fish carriers) that has evolved over decades to handle big fish. This includes crowding grids, pumping without impellers, avoid sharp bends, keep the fish in water as much as possible, to mention a few.
Challenge 3: Good water quality
Increasing the biomass density and at the same time moving the fish often between tanks will stress the water quality in the system. With such a high value in the tanks, giving the fish proper water quality is crucial. The solution is to ensure good water circulation in the tanks, and stable and efficient water treatment. Using circular tanks and correct diameter/height ratio ensures even water distribution and minimized risk of H2S or low oxygen areas. Traditional biofilters are complex and difficult to grow, but there are alternatives with either a hybrid flow-through system, or electrochemical water treatment. A typical hybrid flow-through system will not include biofilter, but CO2 degassing and particle removal, and a higher exchange of water than RAS system. Lately, electrochemical water treatment solutions is proven as an excellent alternative as well.