Susceptibility of Baltic and East Atlantic salmon Salmo salar stocks to Gyrodactylus salaris (Monogenea)

[摘要] ABSTRACT: The susceptibility of a Baltic salmon stock Salmo salar (Indalsälv, central Sweden) to Norwegian Gyrodactylus salaris (Figga strain, central Norway) was experimentally tested and compared with previously obtained results on EastAtlantic salmon (Lierelva, SE Norway). Contrary to expectation, the Baltic salmon, which had no prior exposure to this parasite strain, appeared almost as susceptible as the Norwegian salmon parr that naturally experience G. salaris-inducedmortality. Individually isolated salmon of both stocks sustained G. salaris infections with little evidence of innate resistance. A few individuals of the Indalsälv stock controlled their infection from the beginning, but overall there wasconsiderable heterogeneity in the course of infection in both stocks. On individual hosts, G. salaris growth rates declined steadily throughout the infection, a trend which was particularly marked amongst the Lierelva stock. On shoalingLierelva fish, there was some evidence of reduced parasite population growth towards the end of the infection; this was not apparent in Indalsälv fishes. These results reflect a growing awareness that not all Baltic salmon may be resistant to NorwegianG. salaris, and that Norwegian and Baltic G. salaris strains may differ in virulence. Consequently, management decisions concerning this parasite-host system should be based upon the actual, and tested, susceptibility of stocks underconsideration and not upon identification of stocks as either Atlantic or Baltic.

[学科分类] 生物科学（综合）

[关键词] Gyrodactylus salaris;Host-specificity;Resistance;Salmonids