Lice skirts with built-in antifouling help to keep fish safe and well
Sea lice management is one of the most complex issues to deal with at a salmon farm. Until now, there has been no silver bullet available to treat or prevent sea lice infestation sustainably. A wide spectrum of products has been used to control sea lice numbers including pharmaceutical and non-pharmaceutical methods.
Sea lice control methods in salmon farms include oral and immersion treatments. A range of physical methods have been developed over the past decade, ranging from biological control using cleaner fish, the use of warm water in thermolicers, laser intervention and flushing with hydrolicers. In every aspect, innovators have been thinking outside the box.
In a recent article it was shown quantitatively that in-feed treatments and long-term usage of skirts wrapped around the top portion of salmon pens are the most cost-effective approach for sea lice management. The use of skirts is seen by some to be one of the sustainable sea lice management strategies. One of the major limitations in terms of mass acceptance of this strategy has been the potential for reduced water exchange and hence reduction in dissolved oxygen (DO) levels inside the net.
To solve this problem there are couple of innovative products in the industry that claim a healthy water permeability. However, this water permeability is limited to a few days to a few weeks depending on the intensity of biofouling at the site and the time of year. Biofouling species such as algae, hydroids etc cover the “pores” in the lice skirts, thus making them impermeable within a relatively short time. The lice skirts need to be cleaned frequently to maintain water permeability, leading to higher operational costs and possibility of wear and tear of the lice skirt fabric.
Until now, there has been no solution to reduce fouling growth on the skirts. If the base material was to be coated with antifouling paint, then the “pores” of the fabric would occlude and restrict water permeation. Garware Technical Fibres Ltd. has developed the industry’s first lice skirt which is water permeable but at the same time has built-in antifouling properties. The lice skirt fabric, called X12-V2, has been woven using the patented V2 yarn which is a composite yarn comprising a polymer and metallic copper. Copper ions leach out at an extremely slow rate and discourage biofouling species from settling on the X12-V2 fabric.
In a recent full-sized 120m pen trial conducted in Scotland, the X12-V2 fabric showed reduced fouling as compared to standard polyester. X12-V2 skirts have the potential to not only reduce cleaning costs, but also allow water permeability for a longer duration compared to other fabrics. The reduced cleaning frequency on the robust X12-V2 skirt makes it more durable and longer-lasting.
Featured: The X12 V2 lice skirt on cage
1: Bio-fouling on standard lice skirt
2: Reduced bio-fouling on X12-V2 Lice skirt