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Effects of fish age versus size on the development of whirling disease in rainbow trout

2005; Inter-Research; Volume: 63; Linguagem: Inglês

10.3354/dao063069

1616-1580

EKN Ryce, AV Zale, Elizabeth MacConnell, M. E. Nelson,

Invertebrate Immune Response Mechanisms

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 63:69-76 (2005) - doi:10.3354/dao063069 Effects of fish age versus size on the development of whirling disease in rainbow trout Eileen K. N. Ryce1,*, Alexander V. Zale1, Elizabeth MacConnell2, Mark Nelson1 1Montana Cooperative Fishery Research Unit, US Geological Survey, Department of Ecology, Montana State University,Bozeman, Montana 59717, USA2US Fish and Wildlife Service, Bozeman Fish Health Laboratory, 920 Technology Boulevard, Bozeman, Montana 59715, USA *Email: eryce@state.mt.us ABSTRACT: We examined the effects of both fish age and size on the development of resistance to whirling disease in Erwin strain rainbow trout. Previously, we demonstrated that juvenile rainbow trout became resistant to development of the disease when first exposed to triactinomyxons of the parasite Myxobolus cerebralis at about 9 wk post-hatch when raised at 12°C, but ages and sizes of fish used in that experiment were confounded (Ryce EKN, Zale AV, MacConnell E [2004] Dis Aquat Org 59:225–233). In this study, rainbow trout of the same age and different sizes, and the same size and different ages, were exposed to the parasite to distinguish the influences of age and size. Fish were reared at 3 different water temperatures prior to exposure to produce groups with different growth rates and were exposed to the parasite at 7 or 9 wk post-hatch. Disease severity was affected by both age and size at first exposure, but the effects were not independent. An increase in fork length from 36 to 40 mm among fish exposed at 7 wk post-hatch did not confer increased resistance, but the same increase in size at 9 wk post-hatch did. Similarly, an increase in age from 7 to 9 wk post-hatch among fish exposed at 36 mm fork length did not confer increased resistance, but the same increase in age at 40 mm did. Rainbow trout must be both 9 wk post-hatch or older and at least 40 mm in fork length at time of exposure to exhibit enhanced resistance to whirling disease. Resistance to disease was not associated with the level of skeletal ossification. KEY WORDS: Myxobolus cerebralis · Whirling disease · Resistance · Age · Size · Rainbow trout Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 63, No. 1. Online publication date: January 25, 2005 Print ISSN: 0177-5103; Online ISSN: 1616-1580 Copyright © 2005 Inter-Research.