Modeling salmon lice effects on sea trout population dynamics using an individual-based approach

Salmon lice Lepeophtheirus salmonis infestation of sea trout Salmo trutta results in both additional marine mortality and behavioral changes which may contribute to population decline. For effective management activities that increase exposure salmon lice, such as aquaculture, it is necessary have a full understanding how affect populations. An individual-based model (IBTRUTTA) was therefore developed investigate the potential effects on abundance dynamics based data from River Halselva Altafjord system northern Norway. This allowed investigation effect lice-induced also compensatory salmonid mechanisms premature return freshwater, either persistent for overwintering or transitory after could go back sea. It found that, absence mechanisms, even low rates lead marked declines abundance. Compensatory had reduce these declines, but resulted reduced body mass returning adults. The shape stock-recruitment relationship shown strongly impacted population.