Rapid proliferation of the parasitic copepod, Salmincola
californiensis (Dana), on kokanee salmon, Oncorhynchus nerka (Walbaum), in a large Colorado reservoir
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Title
Rapid proliferation of the parasitic copepod, Salmincola
californiensis (Dana), on kokanee salmon, Oncorhynchus nerka (Walbaum), in a large Colorado reservoir
californiensis (Dana), on kokanee salmon, Oncorhynchus nerka (Walbaum), in a large Colorado reservoir
Description
Ecologically and economically valuable Pacific salmon and trout (Oncorhynchus spp.) are widespread and susceptible to the ectoparasite Salmincola californiensis (Dana). The range of this freshwater copepod has expanded, and in 2015, S. californiensis was observed in Blue Mesa Reservoir, Colorado, USA, an important kokanee salmon (O. nerka, Walbaum) egg source for sustaining fisheries. Few S. californiensis were detected on kokanee salmon in 2016 (<10% prevalence; 2 adult S. californiensis maximum). By 2020, age-3 kokanee salmon had 100% S. californiensis prevalence and mean intensity exceeding 50 adult copepods. Year and kokanee salmon age/maturity (older/mature) were consistently identified as significant predictors of S. californiensis prevalence/intensity. There was evidence that S. californiensis spread rapidly, but their population growth was maximized at the initiation (the first 2–3 years) of the invasion. Gills and heads of kokanee salmon carried the highest S. californiensis loads. S. californiensis population growth appears to be slowing, but S. californiensis expansion occurred concomitant with myriad environmental/biological factors. These factors and inherent variance in S. californiensis count data may have obscured patterns that continued monitoring of parasite–host dynamics, when S. californiensis abundance is more stable, might reveal. The rapid proliferation of S. californiensis indicates that in 5 years a system can go from a light infestation to supporting hosts carrying hundreds of parasites, and concern remains about the sustainability of this kokanee salmon population.
Creator
Lepak, Jesse M.
Hansen, Adam G.
Hooten, Mevin B.
Brauch, Daniel
Vigil, Estevan M.
Subject
Gill lice
Intensity
Invasion
Maturity
Prevalence
Extent
10 pages
Date Created
2021-09-28
Type
Article
Format
application/pdf
Language
English
Is Part Of
Journal of Fish Diseases
Collection
Citation
Lepak, Jesse M. et al., “Rapid proliferation of the parasitic copepod, Salmincola
californiensis (Dana), on kokanee salmon, Oncorhynchus nerka (Walbaum), in a large Colorado reservoir,” CPW Digital Collections, accessed April 19, 2025, https://cpw.cvlcollections.org/items/show/251.
californiensis (Dana), on kokanee salmon, Oncorhynchus nerka (Walbaum), in a large Colorado reservoir,” CPW Digital Collections, accessed April 19, 2025, https://cpw.cvlcollections.org/items/show/251.