Distribution, Prevalence, and Maximum Intensity of the Ectoparasitic CopepodSalmincolacf.Edwardsiiin Brook Trout in Wisconsin Streams

Abstract

Since the late 19th century the ectoparasitic copepod Salmincola cf. edwardsii have been observed infecting brook trout Salvelinus fontinalis in Wisconsin streams. A perceived increase in the incidence of S. cf. edwardsii infection across the state and the observation of an S. edwardsii epizootic leading to declines in brook trout recruitment in Ash Creek, Wisconsin, have raised concerns about the extent to which S. edwardsii threaten other populations of brook trout in Wisconsin streams. In 2013-2017, brook trout were inspected in 282 streams across the state to determine the distribution, prevalence, and maximum intensity of infection of adult female copepods whose morphology was consistent with S. edwardsii. Salmincola cf. edwardsii were present in 79% of streams and absent from 21%. Prevalence of infection ranged from 0.4% to 100% where the parasite was present. Maximum intensity of infection was low (1-5 S. cf. edwardsii) in 31% of streams, moderate (6-14) in 35%, and high (15) in 34%. Maximum intensity was high and prevalence exceeded 90% of brook trout in 9 streams, which suggests epizootics as observed in Ash Creek are uncommon. Our statewide distributional data is critical to understanding the scope of S. cf. edwardsii infection of brook trout in Wisconsin's recreational fisheries and will provide a baseline for ongoing and future investigations of S. cf. edwardsii-brook trout dynamics.

<i>Salmincola edwardsii</i> (Copepoda: Lernaeopodidae) Parasitic on Southern Asian Dolly Varden, <i>Salvelinus malma</i> <i>krascheninnikova</i>, from Hokkaido Island, Japan, with the Southernmost Distribution Record of the Copepod in Asia

“…In North America, S. edwardsii has been studied for its taxonomy and morphology (Wilson 1915;Fasten 1920;Kabata 1969;Ruiz et al 2017), attachment sites (Black 1982), reproduction (Fasten 1914), hatching, larval development and growth (Fasten 1920;Poulin et al 1990a;Curtis 1993, 1994), larval ecology (Fasten 1913;Poulin et al 1990bPoulin et al , 1991a, occurrence on wild hosts (Black et al 1983;Bertrand et al 2008;Mitro 2016;Mitro and Griffin 2018;White et al 2020) and hatchery hosts (Hare and Frantsi 1974;Duston and Cusack 2002), impact on host (Vaughan and Coble 1975;Ruiz et al 2017), and treatment (Duston and Cusack 2002). In contrast, much remains unstudied about the biology of S. edwardsii in East Asia: the species was examined only in taxonomic and faunal research in the Russian Far East (Markewitsch 1937(Markewitsch , 1956Gussev 1962Gussev , 1987Pugachev 1984;Shedko and Shedko 2002;Shedko et al 2005;Sokolov et al 2012;Busarova et al 2017) and Japan (Shedko and Shedko 2002;this paper).…”

Two Copepods <i>Salmincola edwardsii</i> and <i>Salmincola markewitschi</i> (Lernaeopodidae) Parasitic on Chars (<i>Salvelinus</i> spp.) Reared in a Salmon Museum, Northern Japan

“…In Fast East Asia, the species has been reported from southern Asian Dolly Varden in Russia (e.g., Shedko and Shedko 2002;Shedko 2005;Shedko et al 2005a, b;Sokolov et al 2012) and Japan (Shedko and Shedko 2002;Nagasawa 2020a, b;Nagasawa and Kawai 2020). In North America, this copepod is known to infect both wild and hatchery salmonids (e.g., Hare and Frantsi 1974;Black et al 1983;Duston and Cusack 2002;Mitro 2016;Ruiz et al 2017;Mitro and Griffin 2018;White et al 2020; see Nagasawa 2020a for the other literature). The col-lection of S. edwardsii in this study represents the first record of the species from captive fish in Far East Asia.…”

Relative importance of host‐dependent versus physical environmental characteristics affecting the distribution of an ectoparasitic copepod infecting the mouth cavity of stream salmonid

“…Physical environmental factors such as water temperature and flow velocity can influence the development, infection, and abundance of Salmincola spp. (Conley & Curtis, 1993;Mitro & Griffin, 2018;Monzyk et al, 2015;Vigil et al, 2016). Therefore, we measured multiple physical environmental factors (water temperature, stream width, stream depth, substrate score, and flow velocity) at 11 sites in July (Figure 1; Table S1).…”