Rhabdochona cotti (Nematoda: Rhabdochonidae) in mottled sculpins, Cottus bairdi, from the Ford River, Michigan.

A total of 933 mottled sculpins, Cottus bairdi Girard (Cottidae), was examined for Rhabdochona cotti from April 1983 through November 1986 from 3 localities (up-river, middle, down-river) in the Ford River in Michigan's Upper Peninsula. The prevalence and mean intensity of R. cotti were highest in sculpins from the middle (37%) and up-river localities (2.0), respectively. The intensity of R. cotti significantly increased with host length at the middle and down-river localities. Rhabdochona cotti did not exhibit consistent seasonal infection patterns at each location when the data were analyzed seasonally within and between years. Gravid R. cotti infected sculpins in most seasons of each year at the up-river and middle localities. The limited occurrence of R. cotti in sculpins in North America is summarized and discussed.