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

Discussion
Lake Erie is the shallowest Great Lake and the second smallest in surface area, only Lake Ontario
is smaller. Lake Erie has a mean depth (maximum) of 19 m (64 m), length of 388 km, width of 92
km, and a surface area of 25,700 km 2 . Water flows from Lake Erie to Lake Ontario through the
Niagara River and the Welland Canal. Cudmore-Vokey and Crossman (2000) listed 107 fish
species that are established in Lake Erie. However, the number of fish species examined and not
examined for parasites from this lake exceed 107 because several fish species examined for
parasites were not listed as established species by Cudmore-Vokey and Crossman (Anguilla
rostrata, Cyprinella whipplei, Notropis anogenus, N. heterodon, Opsopoeodus emiliae,
Moxostoma aureolum, Salvelinus fontinalis, Cottus cognatus, Sander canadensis, and S.
glaucum), plus the one remaining discrepancy may be due to the use of synonyms for the
scientific name of a fish species.
The study by Dechtiar and Nepszy (1988), involving 10 fish species, reported the most parasite
species (123, not including agnaths)–Protozoa (11), Digenetic Trematoda (31), Monogenea (25),
Cestoda (17), Nematoda (14) Acanthocephala (11), Crustacea (10), Hirudinea (3), and Mollusca
(1). Other prominent studies include Bangham (1972) and those by Crites and his co-workers in
the Bass Island region of eastern Lake Erie. Only three studies (making up 5% of all studies) have
been conducted since 1990.
Pathogenic Parasites
Protozoans
Ichthyophthirius multifiliis, Trichodina domerguei, T. urinaria, and Capriniana piscium occurred
in heavy infections and are considered pathogenic to some fish species (Dogiel et al. 1958;
Reichenbach-Klinke and Elkan 1965; Reichenbach-Klinke 1973). Ichthyophthirius multifiliis can
cause weight loss and mortality in fish (Davis 1944; Elser 1955; and Allison and Kelly 1963).
Trichodina spp. can cause severe hyperplasia of the gill lamellae and inflammation of the ureters
(Richardson 1938; Davis 1947; Hoffman and Lom 1967). Dechtiar (1972a) reported mortality of
young Perca flavescens mainly to Ichthyophthirius multifiliis and Trichodina spp.
Henneguya spp., Myxobolus spp., and Thelohanellus notatus are myxozoans that were found in
the gills, kidney, muscle, mouth tissue, connective tissue, skin, cartilage, fins, heart, mesentery
and bile ducts. These protozoans can cause weight loss and excessive damage to the gills, muscle,
internal organs, and skin of fish (Dogiel et al. 1958; Reichenbach-Klinke and Elkan 1965;
Reichenbach-Klinke 1973).
Of the microsporans found, the effect of Glugea hertwigi on Osmerus mordax was the most
notable, especially in Lake Erie. Cysts of G. hertwigi were first found in O. mordax in Lake Erie
in 1960 by Dechtiar (1965b). These cysts can be found in the intestinal wall, gonads, fins, viscera,
and other organs. Glugea hertwigi is probably the most abundant and important parasite of O.
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