An Early Assessment of the Effects of the Freshwater Parasitic Copepod Salmincola californiensis on Juvenile Spring Chinook Salmon Onchorhynchus tshawytscha Osmoregulation

Parasitic copepods have been to blame for many physiologic malfunctions within salmonids throughout the history of restoring wild salmonid populations. The interaction of the freshwater parasitic copepod, Salmincola californiensis, with Onchorhynchus spp. has been ignored for the past thirty years. What little research that has been conducted has focused on the elimination of S. californiensis from hatchery settings. S. californiensis is a prevalent parasite in artificial reservoirs and natural river systems throughout the Willamette Valley in Oregon. While migrating to the ocean, juvenile Chinook salmon (Onchorhynchus tshawytscha) spend large amounts of time in artificial reservoirs, where they obtain infections of S. californiensis. The primary focus of this study is to investigate what the effects the presence of S. californiensis may be on juvenile Chinook salmon. Ion regulation of infected and uninfected fish are assessed for this study.  The first of two years’ blood sodium and magnesium concentrations of both infected and uninfected fish reared in a hatchery setting were analyzed to assess osmoregulation. Implications of the presence of S. californiensis on juvenile Chinook salmon are taken into consideration and assessed.