Parasites of Fish from the Great Lakes - Great Lakes Fishery ...

Cestodes
Eubothrium crassum, E. rugosum, E. salvelini, Cyathocephalus truncatus, Triaenophorus
crassus, and T. nodulosus are adult cestodes that have been reported to cause pathology to fish
(Vik 1954, 1958; Smith and Margolis 1970; Boyce 1979). Larval cestodes (plerocercoids) of
Diphyllobothrium spp., Ligula intestinalis, Proteocephalus ambloplitis, Triaenophorus crassus,
T. nodulosus, and Triaenophorus sp. can cause various pathology and problems to fish, including
destruction of ovary and oogenic tissue, sterility, haemorrhage caused by moving plerocercoids,
poor condition and stunting (Esch and Huffines 1973; Hoffman and Dunbar 1961; McCormick
and Stokes 1982). It is also possible that the occurrence of Triaenophorus crassus and
Triaenophorus sp. in the muscle of salmonids may cause difficulties in marketing these fish
(Hoffman 1941; Miller 1945, 1952; Welch 1950, 1952; Warren 1952). Problems associated with
muscle of fish infected with Triaenophorus include tissue reduced to homogenous mass as well as
haemorrhage and lesions caused by moving plerocercoids, and encapsulation of plerocercoids,
accompanied by inflammation (Pronina 1977; Davydov 1981; Rosen and Dick 1984).
Nematodes
Wright (1879) was the first study on a parasite infecting a fish from Lake Superior and that
parasite was the nematode Cystidicola stigmatura in the swim bladder of Salvelinus namyacush.
Cystidicola farionis infects the swim bladder of coregonines, salmonines and Osmerus mordax,
and C. stigmatura occurs in the swim bladder of Salvelinus spp. Black (1984) reported on swim
bladder lesions in S. namaycush that may have been caused by adult C. stigmatura. The larval
stages of Contracaecum sp., Hysterothylacium brachyurum, and Raphidascaris acus occurring in
the viscera, including the liver, can cause inflammation, damage, and fibrosis in a variety of
fishes, including salmonids (Williams 1967). Dick et al. (1987) believed that efforts to establish
an Oncorhynchus mykiss population in an inland lake failed because of high intensities of
Contracaecum spp.
Acanthocephalans
Of the adult acanthocephalans, Acanthocephalus dirus, Echinorhynchus lateralis, and
Echinorhynchus salmonis are the most-important species causing inflammation of the intestinal
tract, thus reducing the amount of surface area for nutrient absorption in their fish hosts (Bullock
1963; Pippy and Sandeman 1967; Schmidt et al. 1974). Pomphorhynchus bulbocolli caused
erosion of the epithelium, marked cellular reaction, and the formation of a fibrous capsule around
its proboscis when it penetrated the intestinal wall (McDonough and Gleason 1981).
Leeches
The first report of a parasitic organism from Lake Superior was Verrill (1871) who commented
on the occurrence of the leech Piscicola punctata, but did not document it infecting a fish.
Leeches occasionally cause fish mortalities (Rupp and Meyer 1954). However, leeches are not
important pathogens of fish in Lake Superior to date, except for Actinobdella inequiannulata that
can damage the gills and operculum of catostomids by eroding the epithelium and causing
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