Onshore Vs inland: what is the preferred location for a RAS facility?

Yoav Dagan | VP Business Development

09.02.2021

When considering the ideal location for a RAS (Recirculating Aquaculture Systems) facility, there are many who support building close to coastal shoreline areas, relying on the traditional notion that it’s better and more natural for fish to grow as close as possible to their natural habitat – the ocean. These supporters also build a case from a practical point of view, claiming that a seaside location enables higher water exchange, which promotes greater stability in water parameters by continuous and more efficient dilution of toxins and nitrates in the water.

But that’s not always the case. In fact, there are many advantages of building a RAS facility far from shore. Here are a few examples:

Stability of water parameters

Onshore RAS systems that introduce large volumes of water may actually be more at risk of unstable water parameters, because this requires the integration of many sophisticated systems to balance the pH, bicarbonate levels, and microbiology of the water. The more the aquaculture system relies on additional new water, the greater the risk of instability in the water parameters and the risk of destroying the very important microbiological community that must be managed within the RAS.
Moreover, today there are excellent de-nitrification systems that break down fish wastes and nitrates in the water very effectively, maintaining optimal stability of water parameters. There is therefore no need to introduce great volumes of water to the system in order to dilute the toxins, waste particles and nitrates.

Biosecurity and introduction of diseases into the facility

Since seawater is a significant source of pathogens, the greater the volume of seawater entering the system, the greater the risk of introducing pathogens into the system. Therefore, in a facility with a high water-exchange rate, more complex processes of water disinfection and treatment are required.

Increased power consumption

When introducing large volumes of seawater into the system, a variety of follow-on actions are required, such as disinfection, temperature adjustment, pumping, and treatment of this increased water flow for discharge. All of these are high-energy operations, and therefore result in higher energy costs. What’s more, a facility that is on the coast is usually located higher than sea level, so the water must also be raised to the height of the facility, which entails the use of extremely powerful pumps that also consume a lot of energy.

Air conditions near the sea

Sea air is full of spray, which might also be a source of disease contamination in RAS facilities. To filter the spray and prevent it from entering the facility, sophisticated ventilation systems must be installed – yet another energy-intensive device.
In many existing RAS technologies, there is a trickling filter unit to enable efficient cooling of the water in a dry environment. High humidity levels near the sea may impair the efficiency of these systems, and therefore RAS facilities built in such locations must usually be equipped with additional air-drying systems. The humidity can also damage systems inside the facility, necessitating more frequent maintenance.

Seawater conditions

In terms of the environmental conditions of the water, proponents of coastal facilities claim that the best conditions for the fish will always be their natural environment – that is, the sea. However, inland facilities located far from the sea which have low water-exchange rates enable almost complete control over water parameters and continuously operate at optimum conditions. The water chemistry can be adjusted to support optimum fish growth – for example calcium, which is present in water only in low concentrations restricting growth rate in some locations. In RAS, you can adjust water chemistry and reduce the rate of malformations and increase growth in the fish.
In addition, studies have shown that, in terms of Feed Conversion Ratio (FCR), performance is higher for salmon raised in a less saline environment than in a marine environment.

Sustainability

Obviously, a facility that releases smaller amounts of water into the environment and consumes less energy is more sustainable. In addition, a facility that releases large volumes of water into the sea is at higher risk for fish escape, jeopardizing the biodiversity in the local ecosystem. To prevent this, various protection mechanisms must be installed.
Beyond this, seashores in most parts of the world are considered ‘sensitive’ areas, which means that any construction project in such locations requires the submission of a comprehensive EIA – Environmental Impact Assessment report. These can take years to produce, require public approval and may significantly delay a project.

Smolts production

In the case of smolts production, proximity to the sea-based farm is vital and clearly these facilities must be located onshore. However, also in smolts facilities, special consideration should be given to disease prevention. Sophisticated air filtration systems ought to be integrated in order to prevent spray from the sea entering the facility, and advanced water treatment systems are required in order to treat the seawater entering the system. Moreover, water temperatures should be adjusted before the smolts are to be moved to the sea-based farm in order to reduce stress and mortality rates.

The development of RAS technology in recent years enables us to establish a facility almost anywhere in the world, while still maintaining full control over environmental conditions. Therefore, the whole issue of choosing the location of a facility has moved from the realm of what is possible (where can a facility be built?) to what is viable (where should a facility be built?). The traditional notion that it’s better to raise fish as close to their natural habitat as possible is no longer the obvious answer, as there are many points in favor of the opposite point of view.
This is the essence of the revolution that RAS technology has brought to the world of aquaculture – it enables barriers and limitations to be broken down, making way for discussion on the question of how to properly raise fish, and driving the whole industry to achieve better, more sustainable performance.