DAO 114:139-146 (2015)  -  DOI: https://doi.org/10.3354/dao02855

Proliferative kidney disease in brown trout: infection level, pathology and mortality under field conditions

Heike Schmidt-Posthaus1,*, Regula Hirschi1, Ernst Schneider2

1Centre for Fish and Wildlife Health, Department of Infectious Diseases and Pathobiology, University of Berne, Laenggassstrasse 122, PO Box 8466, 3001 Berne, Switzerland
2Alte Landstrasse 156, 8800 Thalwil, Switzerland
*Corresponding author:

ABSTRACT: Proliferative kidney disease (PKD) is an emerging disease threatening wild salmonid populations. In temperature-controlled aquaria, PKD can cause mortality rates of up to 85% in rainbow trout. So far, no data about PKD-related mortality in wild brown trout Salmo trutta fario are available. The aim of this study was to investigate mortality rates and pathology in brown trout kept in a cage within a natural river habitat known to harbor Tetracapsuloides bryosalmonae. Young-of-the-year (YOY) brown trout, free of T. bryosalmonae, were exposed in the River Wutach, in the northeast of Switzerland, during 3 summer months. Samples of wild brown trout caught by electrofishing near the cage location were examined in parallel. The incidence of PKD in cage-exposed animals (69%) was not significantly different to the disease prevalence of wild fish (82 and 80% in the upstream and downstream locations, respectively). The mortality in cage-exposed animals, however, was as low as 15%. At the termination of the exposure experiment, surviving fish showed histological lesions typical for PKD regression, suggesting that many YOY brown trout survive the initial infection. Our results at the River Wutach suggest that PKD in brown trout does not always result in high mortality under natural conditions.


KEY WORDS: PKD · Salmo trutta · Tetracapsuloides bryosalmonae · Mortality · Renal pathology · Water temperature


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Cite this article as: Schmidt-Posthaus H, Hirschi R, Schneider E (2015) Proliferative kidney disease in brown trout: infection level, pathology and mortality under field conditions. Dis Aquat Org 114:139-146. https://doi.org/10.3354/dao02855

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