Using lights to lure lice to their deaths
A Chilean company has developed a system for reducing lice levels in salmon cages by attracting them with lights and then sucking them into a filter trap.
Indesol, which supplies photoperiod lighting, remotely operated vehicles and oxygen monitors to the salmon farming industry, is behind the innovation.
Company manager Raúl Álvarez told Fish Farming Expert’s Chilean sister site, Salmonexpert.cl, that lice were photosensitive and were attracted by a light source to a suction cone “where with programmed periodic suctions they are extracted from the water and captured in a filter for their subsequent elimination”.
The lights and suction are programmable and can be altered depending on the conditions specific to a farm, said Álvarez.
The objective of the system is the extraction of free-moving parasites in the water column to reduce their population and lower the rate of reinfection of fish.
“The methods and devices that are currently used are focused on eliminating the parasite attached to fish,” said Álvarez.
‘Reinfected in hours’
“Today, the amount of free parasites in the water is such that after a treatment the fish are reinfected in a matter of hours. This causes an increase in the number of treatments per farm and, therefore, an increase in the cost of production.
“This situation worries the industry worldwide: companies are looking for ways to mitigate the volume of free parasites in the water.”
The Indesol executive proposes the installation of three lice traps per cage, with scheduled suction operations, for the whole period that salmon are in the cage.
No impact on environment
He said that the among the advantages of the system are that the total amount of free-moving lice falls, it decreases the rate of the reinfection of fish, the system can be installed in the side of the cage without hindering operations, and it does not have an impact on the environment.
Álvarez said that tests have been carried out with different colours of lights and combinations of colours to find which are most effective for attracting lights.
“We also have a patent application for this development, and we are applying to [state development funding agency] Corfo to finance this initiative for the Chilean salmon industry.”
The trap is not Indesol’s only weapon against lice. It has also developed Shock Out, a system that uses a low-power electric current to remove lice from salmon.