Re-circulating Aquaculture Systems (RAS)

1. Sustainability problem: Food Security (Depletion of Fish Stock)

According to the FAO approximately 57 percent of fish stocks are fully exploited and another 30 percent are over-exploited, depleted or recovering. Whilst drought conditions affect food production and the population of fish in seas and rivers reduce, food demand is projected to rise by at least 20 percent globally over the next 15 years according to the World Bank.

2) Technology: Re-circulating Aquaculture Systems (RAS)

The land-based, closed-containment Recirculating Aquaculture Systems (RAS) is a facility that is capable of growing fish like Atlantic salmon and trout from egg to smolt to market-size adult fish everywhere.

  • Developed by the Freshwater Institute, the RAS system incorporates several water-filters, which removes residual waste like leftover food and fish waste and converts it to nitrogen and phosphorous-rich fertilizer
  • Fishes are raised on sustainable fishmeal-free feed and reared in water that is continuously re-circulated through circular tanks and water treatment processes.
  • The aquarium generates its own current, so the fishes swim in a continuous slow-moving circle thereby creating an optimal environment for their growth.
  • RAS technology also allows for the flexibility to produce fish locally in order to reduce transportation cost and carbon emissions.
  • It’s a water-efficient system, which ensures that about ninety-nine percent of the water is recycled.
  • The RAS-raised salmon grow to harvest size about 6 months sooner than salmon in other aquaculture systems


3) Organizational Stakeholders:

  • Supermarkets
  • Non Governmental Organizations that focus on food security
  • Food Businesses
  • Fertilizer-making companies
  • Local government agencies responsible for food security

4) Deploying Technology

  • Undertake a needs assessment to inform the siting of the project within a community where demand for fish will be high
  • Securing a market: arrange a stakeholder engagement session and explain to the relevant people how the system works and its benefits to the community
  • Secure land for the project and proceed to install the Recirculating Aquaculture Systems (RAS)


Comment on ‘Solar: Try windows if roof space is not enough’ by DRB2171

Unlike previous ‘ transparent’ solar cells, which were only partially transparent, these cells, with the help of the Transparent Luminescent Solar Concentrator (TLSC) are clearly transparent.


2 thoughts on “Re-circulating Aquaculture Systems (RAS)

  1. So good! Great solution for farmers wanting to grow fish and not grow food. There’s also a solution, aquaponics, which uses the “wastewater” directly to grow crops without going through an intermediary step of being filtered and extracted. Anything to get the word out on sustainable methods of fishing!


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