The muskellunge as a host for the silver lamprey in the Ottawa River

A new host, Esox masquinongy, the Muskellunge, for the Silver Lamprey, Ichthyomyzon unicuspis, is reported. Fifteen Silver Lamprey/Muskellunge interactions were documented in a 90-km section of the lower Ottawa River, on the Ontario as well as the Quebec side, from Ottawa to Hawkesbury between 1992 and 2001. Sites of attachment were predominantly on the back. Number of marks per host varied between 1 and 31 with a mean of 10.6. There was evidence of cytolytic activity of the buccal gland secretions. Shallowness of the fresh wounds indicated blood feeding rather than flesh feeding. Survival of the host was indicated by the presence of healed wounds in 26.7% of the cases. Muskellunge over 122 cm in total length were preferred over smaller individuals. Lampreys appeared to be more highly concentrated in the 50-km stretch of the lower Ottawa River, between Thurso and Hawkesbury, than they were in the 40-km stretch upstream, between Ottawa and Thurso.