Seeking solutions

Latest developments in non-medicinal strategies for Caligus control

Caligus, an ectoparasite, is the most prevalent pathogen of farmed salmon. It is a chronic infection, insidious in nature, for which we lack a single and effective solution. Caligus costs the industry dear, in treatments and productivity losses. Globally, sea lice control is primarily achieved via chemotherapeutants, a suboptimal approach due to the rapid development of drug resistance and high economical costs.

All major salmon producing countries in the northern hemisphere have invested in searching for alternatives to the use of chemotherapeutants. Results from research and development have been met with relative success and some non-medicinal treatments are being implemented at a commercial scale as a part of a global and integrated strategy for the control of sea lice.

In Chile, research and the application of non-medicinal alternatives is coming at a slower but steady pace. Some solutions are adaptatons from successful examples in the northern hemisphere, whereas others have emerged from local initiatives.

The use of oceanographic tools to study the dynamics of spread and infection is limited to few public and private initiatives and it has not been incorporated into the regulatory framework for the integrated management of aquaculture by the Chilean authorities.Two private enterprises,AVS and Cetecsal, in Chile have developed hydrodynamic models to study the con- nectivity between farms and determine the risk of Caligus infection. Results and spreaders of Caligus.

This information can be integrated in the regulatory framework to improve coordination and management of production and health plans within production areas.The main shortcomings are that models have been developed regular and real-time data on the hydrodynamic and environmental conditions.

New non-medicinal alternatives need to be low cost and relatively effective to become an attractive option to the industry.The most exciting research development of ultrasound technology. The Patagonian blenny (Eleginops maclovinus) has been experimentally tested in cohabitation with salmon and shown to reduce Caligus levels up to 48 per cent in experimental tanks, and

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Dr Daniel Jiménez is head of area analysis at INTESAL de SalmonChile.