Parvicapsula minibicornis in Anadromous Sockeye (Oncorhynchus nerka) and Coho (Oncorhynchus kisutch) Salmon From Tributaries of the Columbia River

The myxosporean parasite Parvicapsula minibicornis is deP. minibicornis infections in Columbia River salmon is hampered by scribed from adult sockeye and coho salmon during spawning migraour poor understanding of the life cycle of this parasite. tions in tributaries of the Columbia River in Canada and the United States. These observations extend the known distribution of this parasite from the Fraser River drainage basin. The parasite was identified in The myxosporean parasite Parvicapsula minibicornis was first deColumbia River salmonids using polymerase chain reaction (PCR) and scribed from the kidney of adult sockeye salmon (Oncorhynchus nerka) by in situ hybridization, but unlike in Fraser River salmon, it was not spawning at Weaver Creek, a tributary of the Fraser River in British observed in conventional histological preparations of the kidney. PrevColumbia, Canada (Kent et al., 1997). Pathological changes of the kidalence of the parasite determined by PCR was higher in spawning sockney were associated with P. minibicornis (Raverty et al., 2000; Steye from the Fraser River than in those from the Okanagan River. Our Hilaire et al., 2002), suggesting that severe infections may contribute ability to explain the relatively low prevalence and absence of clinical to prespawn mortality observed among prematurely migrating sockeye This content downloaded from 157.55.39.49 on Mon, 29 Aug 2016 04:36:49 UTC All use subject to http://about.jstor.org/terms