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Indicator 2.6.4
by Contact on 8 October 2026
Requirement
Indicator scope: cages The UoC shall ensure that cages are sited under at least one of the following conditions: – In water that is at least twice the cage depth; or, – ≥10m above the bottom of the waterbody; or, – During periods at >75% peak biomass, the velocity of the current below the cages is >0.1 m/s, measured according to Appendix 8 (8.4).3333An exemption applies to sites situated in areas classified as having a “hard bottom”. Evidence is required to support the classification “hard bottom”.
How Do I Interpret This Requirement?
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The UoC should initially determine the depth of the waterbody in comparison to the depth of the cage.
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Measurements should take place at the lowest water level and from the bottom of the cage.
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Depth should also be measured from the outer circumference of the culture containment space, i.e. excluding predator nets, mortality collection chambers etc.
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In tidal systems, the depth should be measured at mean low water spring tide (MLWS).
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If the depth of the water column (surface to seafloor) is less than 10m or less than double the cage depth, the UoC should measure the current velocity below the cage to determine whether the >0.1 m/s threshold is met.
Evidence of Implementation
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Results of measurements which demonstrate that all cages in the UoC meet the depth/current velocity requirements in Indicator 2.6.4.
Auditors Should Confirm
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The UoC has provided evidence demonstrating that all cage systems meet the siting requirements outlined in Indicator 2.6.4.
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If mean current velocity is used to meet the requirement, the UoC has provided evidence that measurements were taken during periods with >75% peak biomass.
Useful Resources
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An example of how to measure current velocity below cages can be found under Section 2.1 of the following document: Marine Scotland (2015): A Technical Standard for Scottish Finfish Aquaculture.