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Planktonic Dispersion of Larval Salmon-Lice, Lepeophtheirus Salmonis, Associated with Cultured Salmon, Salmo Salar, in Western Ireland

Published online by Cambridge University Press:  11 May 2009

Mark Costelloe
Affiliation:
Aqua-Fact International Services Ltd, 12 Kilkerrin Park, Liosbaun, Galway, Ireland
John Costelloe
Affiliation:
Aqua-Fact International Services Ltd, 12 Kilkerrin Park, Liosbaun, Galway, Ireland
Nicola Roche
Affiliation:
Aqua-Fact International Services Ltd, 12 Kilkerrin Park, Liosbaun, Galway, Ireland

Extract

Dispersion of Lepeophtheirus salmonis Kreyer 1838 (Crustacea: Caligidae) larvae from a single cage and also from a farm system was investigated in Ardmore Bay, west coast of Ireland. Surface plankton tows were taken from within a cage and also at various distances from the farm. Highest densities of larvae (maximum, 66·1 m−3) were consistently recorded within the cage. Less than 10% of the larval density recorded inside the cage was found outside at any one time, indicating a high retention of larvae within the cage throughout the sampling period. This was due to a reduction of water movement inside the cage caused by the physical barrier of the net which was fouled during the sampling period. Highest densities of larvae were consistently found in samples taken at 10 m (maximum, 4·8 m−3) from the last cage on the farm in comparison to those taken further away from it (maximum, at 1 km; 0·4 m−3). Regression analysis of the data from each of the sampling dates showed a significant inverse relationship (P=0·001) between distance and larval numbers. The models produced suggest that few louse larvae would have been recovered in samples (i.e. 100 m plankton surface tows) taken more than 2 km from the last cage on the farm. Although the ratio of copepodids to nauplii increased with distance from the farm, the densities of the copepodids did not increase.

Type
Research Article
Copyright
Copyright © Marine Biological Association of the United Kingdom 1996

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References

Anon, ., 1994. An investigation of the production and dispersion of Lepeophtheirus salmonis (Krøyer, 1838) in a number of selected bays on the west coast of Ireland. Report by Aqua-Fact International Services Ltd to the Irish Salmon Growers Association.Google Scholar
Boxshall, G.A. & Defaye, D., ed., 1993. Pathogens of wild and farmed fish: sea lice. West Sussex: Ellis Horwood.CrossRefGoogle Scholar
Heuch, P.A., Parsons, A. & Boxaspen, K., in press. Diel vertical migration - a possible host-finding mechanism in salmon louse (Lepeophtheirus salmonis) copepodids. Canadian Journal of Fisheries and Aquatic Sciences.Google Scholar
Jackson, D., Minchin, D., Duggan, C., Hassett, D., Leahy, Y. & Whitaker, A., 1994. Observations of the larval stages of the salmon louse, Lepeophtheirus salmonis. International Council for the Exploration of the Sea, Mariculture Committee (CM Papers and Reports), CM 1994/F: 14, 5 pp.Google Scholar
Johannessen, A., 1978. Early stages of Lepeophtheirus salmonis (Copepoda, Caligidae). Sarsia, 63, 169176.CrossRefGoogle Scholar
Johnson, S.C. & Albright, L.J., 1991a. Development, growth, and survival of Lepeophtheirus salmonis (Copepoda: Caligidae) under laboratory conditions. Journal of the Marine Biological Association of the United Kingdom, 71, 425436.CrossRefGoogle Scholar
Johnson, S.C. & Albright, L.J., 1991b. The developmental stages of Lepeophtheirus salmonis (Krøyer, 1837) (Copepoda: Caligidae). Canadian Journal of Zoology, 69, 929950.CrossRefGoogle Scholar
Kabata, Z., 1979. Parasitic Copepoda of British fishes. London: The Ray Society.Google Scholar
Løland, G., 1993. Current forces on, and water flow through and around, floating fish farms. Aquaculture International, 1, 7289.CrossRefGoogle Scholar
Schram, T.A., 1993. Supplementary descriptions of the developmental stages in Lepeophtheirus salmonis (Krøyer, 1837) (Copepoda: Caligidae). In Pathogens of wild and farmed fish: sealice (ed. G.A., Boxshall and D., Defaye), pp. 3047. London: Ellis Horwood.Google Scholar
Sokal, R.R. & Rohlf, F.J., 1981. Biometry, 2nd ed.San Francisco: W.H. Freeman.Google Scholar
Tully, O., 1989. The succession of generations and growth of the caligid copepods Caligus elongatus and Lepeophtheirus salmonis parasitising farmed Atlantic salmon smolts (Salmo salar L.). Journal of the Marine Biological Association of the United Kingdom, 69, 279287.CrossRefGoogle Scholar
Tully, O. & Whelan, K.F., 1993. Production of nauplii of Lepeophtheirus salmonis (Krøyer) (Copepoda: Caligidae) from farmed and wild salmon and its relation to infestation of wild sea trout (Salmo trutta L.) off the west coast of Ireland in 1991. Fisheries Research, 17, 187200.CrossRefGoogle Scholar
Wootten, R., Smith, J.W. & Needham, E.A., 1982. Aspects of the biology of the parasitic copepods Lepeophtheirus salmonis and Caligus elongatus on farmed salmonids, and their treatment. Proceedings of the Royal Society of Edinburgh B, 81, 185197.Google Scholar