The Huenquillahue research center in Mowi Chile, Region X, has been analysing the retention capacity of Caligus rogercresseyi larvae for months on Garware cloths, which are to be used as a lice skirt as a mechanical barrier in salmon farming centres. The analysis considered the retention of larvae, the entry of these at different speeds of currents and fixation of copepodites to the fish. This resulted in a high-quality fabric that allows for the containment of infestations and the passage of water flow, allowing for necessary oxygenation in salmon farming centres.

Garware fabrics to be used as lice skirt


The meshes were tested by means of sieves for the forced passage of the water flow with the addition of larvae in the nauplius stage (I-II) and copepodites. They were evaluated in three aspects: their retention capacity of C. rogercresseyi larvae, estimating the percentage of entry of larvae at different current speeds, and with fish to see the fixation of the copepodites that manage to pass through the fabric.

 

In this regard, the Mowi Chile health area noted that, 'The effectiveness tests of the fabrics that have been carried out, in conjunction with the Austral University of Chile, to combat Caligus, have brought good results and we are considering them for the non-drug management alternatives for the control of this parasite.'
 

The results of the study which were carried out by the Austral University, highlight the evaluation of fabric cages in a test channel for the estimation of permeability to the passage of the larvae. They registered a blockage of 99.6 percent of Nauplii larvae and 99.7 percent of Copepoditos larvae, so that they do not enter the cage.
 

Evaluation of fabric cages in a test channel


In each case, the amount of water used was 340 litres with 3,700 larvae per test, totalling more than 133,800 larvae, where a flow of water was applied at current speeds of 0.5, 2 and 3.5 cm * s-1. Thus, the latest generation Garware X12 fabric is recommended as a mechanical barrier against C. rogercresseyi larvae, with its high-quality characteristics and allows the passage of water flow, without greater resistance at medium current speeds. This will be favourable, to maximise the natural oxygenation of the farm.

 

'The skirts in preventing infestation are a physical barrier that surrounds the fish tank cage. Thanks to the X12 fabric that allows the water to flow, this prevents the entry of lice. This allows 80 times more water flow than a common fabric for these purposes. The weave of the X12 cloth blocks the entry of the early stages of the parasite and promotes adequate water exchange,' Marcos Jofre, Business Associate at Garware Technical Fibres, explained.
 

'It is a non-pharmacological product, as part of the strategies to reduce the use of drugs, whose field experience shows a decrease in the frequency of baths of up to 50 percent, with a reduction of lice of up to 60 percent. Thus, we developed a three-dimensional fabric, with an opening of 80 to 150 microns for Norway, and a second generation of 60 to 100 microns for Chile, given that the local sea lice are smaller in numbers, thus generating a product applied to the national market.'
 

Caligidosis infestation is a growth limiting factor in salmon production globally, where the use of antiparasitic products has become less and less effective due to the development of parasite resistance. The global focus, then, has been on the implementation of new complementary non-pharmacological control methods such as tarps, in managing infestations caused by salmon louse. 
 

For more information, visit Garware Technical Fibres' website, HERE.

Alternatively, visit Mowi's website, HERE.
 

Image credit: Garware Technical Fibres

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