Sea lice are a pest that many fish farmers are no doubt more familiar with than they would like to be. Parasites of the sea, they latch onto fish and feed on their bodies relentlessly, causing a variety of issues for both fish and fish farmers.
Despite the wide range of solutions that are on the market to both prevent and treat lice, there is no solution that guarantees 100 percent effectiveness and the issue continues to still plague members of the industry. If your farm is falling victim to these pesky critters, then the best way to manage them is to first gain a comprehensive understanding of the variety of different solutions that are readily available on the market.
Sea lice are a family of salt-water small crustaceans that are also considered to be marine ecoparasites. Approximately 162 Lepeophtheirus and 268 Caligus sub-species of sea lice have been discovered, both of which wreak havoc on fish farms when an outbreak of them occur in a cage system.
These parasitic pests attach to fish and feed upon the blood, mucus and epidermal tissue of their unfortunate hosts. Sea lice are known to be particularly common occurrences amongst farmed salmon, but they aren’t especially picky eaters and all varieties of farmed fish can fall victim to their gluttonous ways.
Certain species of sea louse may target specific fish species, such as the Pacific strand of Lepeophtheirus salmonis which has been recorded to target the three-spined stickleback (Gasterosteus aculeatus), whereas the Atlantic L. salmonis is known to stick solely to Atlantic salmon (Salmo salar), sea trout (Salmo trutta), Arctic char (Salvelinus alpinus) and other such forms of Pacific salmon.
Once a host has been located, the copepodid stage louse will begin feeding and soon develops into the initial chalimus stage. Female sea lice, as well as fully-grown adults and pre-adults are known to be especially aggressive feeders. Their feeding often results in serious damage to fish, including lesions, hyperplasia and inflammation. As a result of this, fish also experience heightened stress levels, which often results in various bodily changes. These changes then result in reduced growth and performance, disease susceptibility and decreased immune responses.
Surprisingly, the instigating factors for infection are not yet known. It is suspected that smolt become infected with sea lice in their larval stage when they enter estuaries in the spring. Adult stages of Lepeophtheirus spp can also transfer under specific laboratory conditions, whilst Caligus spp can transfer much more frequently and easily between fish species.
With limited space for aquaculture production on land, open net-cage farming and development has grown in popularity amongst many farmers, leaving fish vulnerable to infestation from sea lice.
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The Aquaculturists
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