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Gill observations in Atlantic salmon (Salmo salar, L.) during repeated amoebic gill disease (AGD) field exposure and survival challenge
Citation
Taylor, RS and Muller, WJ and Cook, MT and Kube, PD and Elliott, NG, Gill observations in Atlantic salmon (Salmo salar, L.) during repeated amoebic gill disease (AGD) field exposure and survival challenge, Aquaculture, 290 pp. 1-8. ISSN 0044-8486 (2009) [Refereed Article]
DOI: doi:10.1016/j.aquaculture.2009.01.030
Abstract
Amoebic gill disease (AGD) of Atlantic salmon in Tasmania is proactively treated by freshwater bathing when
gross gill assessment (‘gill score’) indicates a moderate level of disease in a cage population. This generally
ensures that few fish are exposed to severe disease symptoms and that few die, but also means that a
proportion of the population shows little gross evidence of AGD. Individuals exhibiting few AGD symptoms at
bath may be more resistant, or simply reflect an uneven spread of the disease through the population. This
study had three main aims, firstly, to determine whether all fish in a cage population eventually require
freshwater treatment after first infection; secondly, to ascertain whether there is any evidence of
development of resistance to AGD; and thirdly, to see if there is a relationship between the level of
proliferative gill reaction to the parasite, assessed by gill score, and time to mortality when the disease is left
untreated. These aims were achieved by following gill score trajectories of individual fish through three
rounds of natural AGD infection and relating these to the eventual fate of the fish in a natural AGD survival
challenge after the second freshwater bath. There was no evidence of complete innate resistance to AGD as
each fish eventually required a first freshwater bath. There was no relationship between the rate of first
infection and the ultimate survival of each fish. For the second and third exposures, significant differences
(Pb0.001) were observed between the surviving fish and those that died in the challenge. Individual gill
scores at the latter measurements were suggestive of development of resistance to AGD. Mortality during a
natural summer AGD challenge in an un-bathed population of fish, that had two previous treated exposures
to the disease, was 67.7% and gill symptoms at the onset of losses accurately predicted the rate of mortality.
© 2009 Elsevier B.V. All rights reserved
Item Details
Item Type: | Refereed Article |
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Research Division: | Agricultural and Veterinary Sciences |
Research Group: | Fisheries Sciences |
Research Field: | Fish Pests and Diseases |
Objective Division: | Animal Production and Animal Primary Products |
Objective Group: | Fisheries - Aquaculture |
Objective Field: | Aquaculture Fin Fish (excl. Tuna) |
UTAS Author: | Taylor, RS (Dr Richard Taylor) |
ID Code: | 60956 |
Year Published: | 2009 |
Web of Science® Times Cited: | 46 |
Deposited By: | NC Marine Conservation and Resource Sustainability |
Deposited On: | 2010-02-23 |
Last Modified: | 2010-04-22 |
Downloads: | 0 |
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