Organic Sea
    The science park
    Vesterballevej 5, 1.22
    DK 7000, Fredericia


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    Fish Welfare

    Fish welfare:

    Water velocity (important for actual access to oxygen and stress of fish))
    Water velocity, average in water column:
    Any species: min 15% of body length per sec.
    Salmonides, min 30% of body length per sec.

    Water exchange
    Water exchange in fish tank: minimum 1 exchange per hour.
    Max holding time in tanks with water exchange of less than 1 exchange per hour (as for transport of fish or handling of fish): 3 hours

    Water Quality
    In fish tanks (outlets as well), the flowing parameters are accepted:
    Oxygen: min: 80% sat.
    Free CO2: Max: 16 mg
    Ammonia NH3/NH4: Max : 0,02 mg N/l
    Nitrate: Max 100 mg N/l
    pH: Min: 6.5 Max 8.4
    Turbidity: min 1 meter of visibility.
    Geosmin: max: 10 ng/l

    Fish density
    Organic Sea standards, does not set a specific fish density in the tanks as a norm, as this is not possible from a fish welfare point of view. Fish welfare is about water quality and water velocity.
    Most fish species are schooling to feel safe, and densities of several hundred kilo of fish per m3, can be optimal as long as the water quality is good. For salmon for an example, if the water quality it good, then in cages with plenty of species, the salmon will typical School in densities of 150-300 kg/m3, for some grouper species, the optimal density will be even quite a bit higher. At low densities some fish species will become territorial, which will cause stress.
    A high density will require a fast water exchange in the tanks, which in itself will generate some limitations.
    A system with a water exchange in the tanks of 1-2 exchanges per can support a fish density of potentially above 150 kg/m3, without compromising fish welfare, as long as the water quality parameters are within the levels listed above at the outlet point of the tank.

    Addition of NaCL or other chemicals cannot be applied for purging.
    Purge tank with equal salinity and quality of water compared to production tanks.
    Purge with levelled levels of NaCl is not permitted.

    Killing method allowed:
    Stunning, electric shock
    If stunning applied, then to reduce stress for a period of up to 30 minutes before killing, it is permitted to transfer the fish to cooled water before stunning.
    The cooled water, should be in equal chemical composition, including salinity compared to the water in purge and production tanks. The fish can be chilled to a maximum of 15 degrees below temperature in purge tank, but to no less than 3 degree C.
    Addition of CO2 is not permitted for pacifying or killing the fish.

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