Environmental factors that influence site selection
Consider environmental factors when selecting a site for your freshwater aquaculture venture. This includes the following:
Soils must be impervious (more than 20% clay) to ensure minimum water is lost through seepage. Clay or clay-loam soils are ideal. Avoid soil types:
- with gravel or sand layers, or rock strata formations
- that are acidic or have the potential to be acidic
- that are permeable with high silt, sand or organic matter that may erode.
An abundant supply of good-quality freshwater is vital to support most aquaculture operations. Sources include dams, rivers and creeks, run-off, irrigation channels and underground bores.
Consider the cost-effectiveness of the water source and if seasonal changes will affect water quality and quantity. Check dam water for contamination from pesticides or heavy metals. Generally, water that is safe for livestock or supports wild fish is safe for aquaculture.
You can determine the ideal water temperature, oxygen requirements and tolerances based on the species being farmed. For instance, 'soft' water low in calcium can cause under-developed, soft-shelled crayfish.
Chemical characteristics of water suitable for animal growth include:
- pH - 6.5 to 8.5
- total alkalinity - 75mg/L to 250mg/L (less than 500mg/L as CaC03)
- total hardness - 75mg/L to 250mg/L (less than 500mg/L as CaC03)
- total alkalinity and hardness - no less than 20mg/L.
Avoid the following types of water:
- domestic water, which may contain chlorine and can be expensive
- water containing high levels of organic matter
- bore water with excess levels of nitrogen, carbon, total dissolved salts, minerals and gases.
Site topography influences the design and layout of ponds. A well-drained, gently sloping site (1-3%) is best as it minimises construction costs.
Sloping ponds allow complete drainage and ensure that discharge drains transfer water to settlement ponds and holding dams where wastewater can be reused. Ideally, facilities should be sited below the water source for easy supply.
Check the site is above flood level to reduce the risk of losing fish during floods or transferring non-native species into the natural river system.
Avoid land that is steep, flat, or floods more than once in 100 years.
Sites near sensitive areas like national parks need certain approvals, especially to discharge drained pond water (containing nutrients and algae). Your site should have room for settlement ponds and holding dams so water can be reused.
Check requirements for buffer zones from houses, waterways or farms which reduce the amount of land available for aquaculture.
Check for chemical contamination
Research the site's previous use to ensure there is no contamination risk from chemical residues that may affect production, saleability and safety of your product.
For more information read our guidelines on Site identification for aquaculture: assessment of chemical contamination in site selection.
These guidelines provide a practical 11-step approach to determining site suitability and safety.
- Find out how to select a site for marine aquaculture.