Effects of fish age and parasite dose on the development of whirling disease in rainbow trout
| Autor: | Alexander V. Zale, Eileen K. N. Ryce, Elizabeth MacConnell |
|---|---|
| Rok vydání: | 2004 |
| Předmět: |
animal structures
Physiology Disease Motor Activity Aquatic Science Biology Models Biological Fish Diseases Aquaculture Animals Juvenile Parasite hosting Protozoan Infections Animal Ecology Evolution Behavior and Systematics Myxobolus cerebralis Ecology business.industry Host (biology) Age Factors Eukaryota biology.organism_classification Hatchery Phenotype Oncorhynchus mykiss Body Burden Rainbow trout business |
| Zdroj: | Diseases of Aquatic Organisms. 59:225-233 |
| ISSN: | 1616-1580 0177-5103 |
| DOI: | 10.3354/dao059225 |
| Popis: | We determined the ages at which juvenile rainbow trout Oncorhynchus mykiss became resistant to the effects of whirling disease following exposure to a range of parasite doses. Heretofore, the development and severity of whirling disease in salmonids was known to be generally dependent on the age or size of fish when first exposed to the triactinomyxon spores of Myxobolus cerebralis; larger, older individuals tended to be less diseased. However, no systematic determination had been made of the exact age at which fish become resistant to the development of the disease. We exposed rainbow trout at 9 ages (1 to 17 wk post-hatch) to 4 parasite dose levels (0, 100, 1000 and 10,000 triactinomyxons per fish). Disease severity was measured using mortality, clinical signs, microscopic pathology, and myxospore counts. Disease and mortality were substantially reduced when exposure to the parasite occurred for the first time at 9 wk post-hatch (756 degree-days at 12 degrees C) or older. High doses elicited more disease among the younger age groups, but the effect was dampened in groups exposed at about 9 to 11 wk post-hatch and absent thereafter. Rainbow trout reared in M. cerebralis-free waters for 9 wk post-hatch or longer, whether in the wild or in a hatchery situation, should experience greater survival and less disease than fish first exposed to the parasite at younger ages. |
| Databáze: | OpenAIRE |
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