Sea Lice AND Salmon - Farmed And Dangerous

2. ARE SEA LICE HARMFUL TO PEOPLE?Sea lice do not harm people, only fish. Sea licecan’t parasitize humans, and because sea licelive on the outside of fish, there is no risk ofeating them. In fact, sea lice are scraped off orfall off soon after fish are caught, which iswhy you rarely see them on the salmon youmight buy. [47]3. ARE THERE DIFFERENT TYPESOF SEA LICE?At least thirteen different species of sea licelive in BC waters. Only Caligus clemensi, Lepeophtheiruscuneifer, and Lepeophtheirussalmonis have been reported on farmed andwild salmon in BC. Caligus clemensi occursthroughout the north Pacific, [38] and along thewest coast of BC and northwest coast of Washington.[39] Lepeophtheirus cuneifer occursalong the northern Pacific coast of Alaska andBC, [40] while Lepeophtheirus salmonis is foundthroughout the northernmost portion of theNorthern Hemisphere. [38] All sea lice parasitizefish, but some sea lice are more specializedthan others. Lepeophtheirus salmonis, forexample, is almost always found only onsalmon.In BC waters, Caligus clemensi and Lepeophtheirussalmonis may damage both farmed andwild salmon, and are a major concern both forthe fish farming industry and for salmon conservationists.While Lepeophtheirus salmonis isoften more prevalent and more damaging thanCaligus clemensi, [38, 110] studies in theBroughton Archipelago in 2003 indicated that20% of chum salmon were infected with Caligusand only 7% with Lepeophtheirus. [109]4. HOW DO SEA LICE HARM FISH?Sea lice eat the mucous, blood and skin ofsalmon. While a few lice on a large salmonmay not cause serious damage, large numbersof lice on that same fish, or just a couple oflice on a juvenile salmon, can be harmful orfatal. The feeding activity of sea lice can causeserious fin damage, skin erosion, constantbleeding, and deep open wounds. [41]The sea louse—which resembles a tiny horseshoecrab—is well adapted to life as a marineectoparasite. [42] Their flattened head is coveredby a shield, and their legs are specializedto allow them to grasp and feed on fish. Mostof the female’s body is dedicated to producinglarge numbers of eggs. What looks like twotails trailing behind are actually strings of eggs.Only gravid (pregnant) females carry them.5. ARE SEA LICE EQUALLY HARMFULTO ALL TYPES OF SALMON?The way salmon react to,and how badly they areharmed by, sea lice infestationsdepend on: [36]■The size and age ofthe fish. Smaller andyounger salmon aremore at risk;Lepeophtheirus salmonis(left) and Caligus clemensi(right) on a pink salmonsmolt.8 Sea Lice and Salmon: Elevating the DialogueAlexandra Morton photo