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Aquaculture Environment Interactions

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AEI 7:67-74 (2015)  -  DOI:

Depth distribution of the amoebic gill disease agent, Neoparamoeba perurans, in salmon sea-cages

Daniel W. Wright1,*, Barbara Nowak2, Frode Oppedal3, Andrew Bridle2, Tim Dempster

1Sustainable Aquaculture Laboratory - Temperate and Tropical (SALTT), School of Biosciences, University of Melbourne, Parkville, VIC 3010, Australia
2Institute of Marine and Antarctic Studies, University of Tasmania, Launceston, TAS 7250, Australia
3Institute of Marine Research, 5984 Matredal, Norway
*Corresponding author:

ABSTRACT: Identifying where and when parasites occur in farming environments is vital to understand transmission dynamics and develop preventative measures that reduce host-parasite encounters. A major parasite concern for Atlantic salmon farming is Neoparamoeba perurans, a marine amoeba that causes the potentially fatal amoebic gill disease (AGD), for which few control options exist. We explored whether free-living N. perurans abundance differs among depths in commercial Atlantic salmon Salmo salar sea-cages. Water samples collected from the surface to 10 m depth at multiple cage sites and times, and subsequently subjected to qPCR analysis, revealed that N. perurans abundance was influenced by depth at the time of year when amoeba numbers were highest, with more amoebae in surface waters. No distinct depth patterns were observed when amoebae were in low abundance. Across all times, temperature and salinity were largely homogeneous throughout cage depths. Possible factors explaining the presence of amoebae at the surface are discussed. Our results suggest that excluding caged salmon from upper cage depths where N. perurans is more abundant could be an effective management strategy to reduce the speed at which initial infections occur and delay the development of AGD outbreaks.

KEY WORDS: Parasite control · Atlantic salmon · Salmo salar · Neoparamoeba perurans · Depth distribution · Sea-cages

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Cite this article as: Wright DW, Nowak B, Oppedal F, Bridle A, Dempster T (2015) Depth distribution of the amoebic gill disease agent, Neoparamoeba perurans, in salmon sea-cages. Aquacult Environ Interact 7:67-74.

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