Fish affected by sea-lice should be bathed in 0.2 ppm of the product (0.1 ppm azamethiphos) for a period of not less than 30 minutes and not more than 60 minutes. Assess water volume as accurately as possible when calculating the amount of product needed for treatment to avoid under- or over- dosing.
To achieve a final concentration of 0.1 ppm azamethiphos, 0.2 g of the product must be added per cubic metre of water, i.e., 1 x 100 g sachet treats 500 cubic metres.
Oxygenation must be provided during treatment, ideally continuously while the fish are crowded in the net and the tarpaulin is fitted to and removed from the cage. Vigorous oxygenation is recommended in the treatment cage. Where several cages are to be treated a large reservoir of oxygen bottles should be available.
Initial preparation of the treatment concentrate should take place in a dry and sheltered location, not more than 48 hours prior to treatment. Operators wearing suitable equipment and protective clothing, should place the number of water soluble bags of the product required for the dosage of an individual cage into a labelled screw-topped polyethylene container, together with a quantity of fresh water (1 litre or more of water for every 200 g of the product). Screw the lid tightly onto the container and gently shake this initial dilution for up to 5 minutes.
When fish are ready to be treated, the diluted suspension of the product should be further diluted into approximately 200 to 1000 litres of sea water and gently stirred for 5 minutes. The polyethylene container, in which the first dilution was prepared, should be rinsed with sea water and the rinsing from this should be added to the sea water dilution tank. This latter mixture should then be immediately and carefully added to the cage by pouring or pumping the mixture into the water as evenly and efficiently as possible using the Bath Technique.
THE BATH TECHNIQUE
In this technique, the depth of the fish cage net is reduced to a known depth at the centre and a tarpaulin placed around the net so that it is totally enclosed. Ensure the base of the cage is not drooping when in the raised position as fish may congregate and come to harm. The volume of water to be treated should be estimated as accurately as possible, restrictive tarpaulins can be used to give a better management of water volume and reduce the amount of product needed depending on biomass of fish to be treated. Oxygenation should begin before the tarpaulin is fitted and continue until the tarpaulin is fully removed after treatment. Once the tarpaulin is in place the product (in the seawater dilution) should be immediately added. When the addition of product diluted in seawater to the tarpaulined cage is completed the treatment time begins. At the end of the treatment time the tarpaulin should be removed as quickly as possible allowing the exchange of clean seawater into the cage. The Bath Technique is designed to ensure the product is used in a totally enclosed volume of water.
Withdrawal period(s)
Withdrawal period: 10 degree days.