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Indicator 4.1.2.7
by Contact on 8 October 2026
Requirement
The UoC shall ensure that the HMP considers crowding activities with the intent of preventing stress, injury and mortality. Crowding activities shall be carried out: a) under supervision; and b) gradually; and c) partially; and d) for a maximum of two hours. An exception applies where a registered veterinarian or aquatic animal health professional demonstrates that exceeding two hours of crowding does not negatively impact fish welfare, in which case the maximum time period shall be defined by the registered veterinarian or aquatic animal health professional.
How Do I Interpret This Requirement?
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Appropriate crowding intensity is achieved when there is a balance between fish welfare, minimising abnormal behaviour and having sufficient fish in the crowd area for an effective handling.
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Abnormal behaviour may be defined as fish behaviour commonly found or seen when fish are stressed.
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During crowding operations consider an appropriate fish density avoiding:
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Vigorous escape behaviour.
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Violent splashing.
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Escape attempts (jumping).
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Burrowing into the crowding net.
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Air gasping.
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Excessive gill movement.
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Inability to fish maintain body position (white sides constantly on surface).
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Skin colour changes.
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Presence of fish scales in the water.
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Narrow deep nets are recommended over wide shallow nets for fish crowding.
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Evidence of Implementation
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Considerations, plans and actions taken pre- and during crowding for achieving an appropriate crowding intensity.
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Records:
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That confirms the monitoring of the crowding, e.g. time and intensity.
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Employees should demonstrate awareness of the established crowding operation.
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Rationale for exceeding the crowding time as directed by the veterinarian or aquatic health professional.
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Auditors Should Confirm
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The crowding operation incorporates considerations for an appropriate crowding, and it is implemented.
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Implementation can be verified by cross-checking the crowding operations with records, information from employee interviews and observations.
Useful Resources
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Stien, L., Nilsson, K., Noble, C., Izquierdo-Gomez, D., Ytteborg, E., Timmerhaus, G., & Madaro, A. (2024) Evaluating a crowding intensity scale and welfare indicators for Atlantic salmon in sea cages. Aquaculture Reports.