The effects of Stephanostomum tenue (Digenea: Acanthocolpidae) on marine aquaculture of the rainbow trout, Salmo gairdneri

McGladdery, S.E.; Murphy, L.; Hicks, B.D.; Wagner, S.K.

Pathology in marine science Proceedings of the Third International Colloquium on Pathology in Marine Aquaculture, held in Gloucester Point, Virginia, USA, October 2-6, 1988: 305-315

1990


Accession: 002248845

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Abstract
Following mass mortalities of maricultured rainbow trout off Prince Edward Island, Canada, in 1985 as a result of infection by metacercariae of Stephanostomum tenue, prevalence and abundance of infection were recorded from rainbow trout held in 4 cages in the same area kept 0.3 m, 1.8 m, 4.9 m, and 7.3 m from the estuary floor, between May and November, 1986. Infections were first noted at the end of June in trout from the 3 cages suspended less than 5 m from the bottom. Infections did not appear in the deeper water cage until late July. Abundance of infection increased steadily until mid-August in the 2 cages held less than 2 m from the bottom. The cages held in water over 4 m from the bottom maintained consistently low levels of infection (<2 metacercariae/fish) from late June until the end of the experiment. Cercarial release from the first intermediate host, the mud dog whelk (Nassarius obsoletus), was restricted to the period when water temperatures exceeded approximately 16-17 degrees C. No correlation was found between cercarial release, salinity, or dissolved oxygen. The pathological effects of this parasite on its accidental trout host and the natural life cycle of S. tenue in the affected estuary system were also investigated.