Higher mortality of the less suitable brown trout host compared to the principal Atlantic salmon host when infested with freshwater pearl mussel (Margaritifera margaritifera) glochidia.

The freshwater pearl mussel (Margaritifera margaritifera) is a highly host-specific parasite, with an obligate parasitic stage on salmonid fish. Atlantic salmon (Salmo salar) and brown trout (Salmo trutta f. trutta and Salmo trutta f.

Host (Salmo trutta) age influences resistance to infestation by freshwater pearl mussel (Margaritifera margaritifera) glochidia.

The freshwater pearl mussel (Margaritifera margaritifera) is an endangered bivalve with an obligate parasitic stage on salmonids. Host suitability studies have shown that glochidial growth and load vary significantly between host strains as well as among individuals of a suitable strain. Variation in host suitability has been linked to environmental conditions, host age and/or size, genetic composition of the host and parasite, or a combination of these factors.

Duration of the parasitic phase determines subsequent performance in juvenile freshwater pearl mussels (.

Host-parasite systems have been useful in understanding coevolutionary patterns in sympatric species. Based on the exceptional interaction of the long-lived and highly host-specific freshwater pearl mussel (FPM; ) with its much shorter-lived host fish ( or ), we tested the hypotheses that a longer duration of the parasitic phase increases fitness-related performance of mussels in their subsequent post parasitic phase, and that temperature is the main factor governing the duration of the parasitic phase. We collected juvenile mussels from naturally and artificially infested fish from eight rivers in Norway.