Occurrence of Salmincola sp. on brook charr Salvelinus fontinalis in Lake Superior

Abstract

Salmincola sp. infect fishes of the family Salmonidae and can negatively affect host health. The parasite–host relationship was examined between Salmincola sp. and a remnant population of brook charr on Isle Royale, Lake Superior. A total of 573 brook charr were collected using boat-mounted electrofishing and angling from 2005 to 2017. Macroscopic examination revealed copepod (Salmincola sp.) infections on gills and fins. Field identifications were confirmed for a subsample of parasites in the laboratory. The preferred attachment location was on the gills, with infections on fins being rare and likely a spillover from large infections in the primary location. Host size was a significant predictor of Salmincola prevalence and parasite load. The distribution of lice within the Tobin Harbor brook charr population was atypical of parasite distributions, because few hosts were uninfected. Gill tissue damage was present in heavily infected fish, but host condition did not vary among Salmincola classifications. The Tobin Harbor brook charr population is highly susceptible to Salmincola infections and infestations are reaching levels that could be influencing host health and future population growth and sustainability.