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

viscera, which may castrate and even kill infected Perca flavescens. Larvae of Eustrongylides
tubifex and adults of Philometra cylindracea may play a role in reduced growth and high
mortality of Perca flavescens (see Allison 1966; Crites 1982; and Salz 1989). If infected fish are
not cleaned in a timely manner, these redworms may move out of these capsules into the body
cavity and cause anglers to possibly discard the infected fish.
Acanthocephalans
High intensities of the acanthocephalans Acanthocephalus dirus, Echinorhynchus salmonis,
Pomphorhynchus bulbocolli, and Leptorhynchoides thecatus can cause fibrosis, inflammation and
hemorrhaging of the intestinal wall of fish resulting in impaired nutrient uptake (Petrushevski and
Kogteva 1954; Bullock 1963; Schmidt et al. 1974; McDonough and Gleason 1981).
Leeches
Only Actinobdella inequiannulata, Myzobdella lugubris, and Piscicola sp. have been reported
from Lake Ontario fishes but in low prevalences and/or intensities. They are of minor
pathological importance, except possibly for A. inequiannulata that can damage the gills and
operculum of catostomids (Dechtiar and Lawrie 1988).
Crustaceans
The copepod parasites Ergasilus spp., Argulus catostomi, and Achtheres spp. can be considered
serious pathogens when they occur in high intensities. Copepod movements on the gills of fish
can cause destruction and hypertrophy of gill filaments. The first legs of Ergasilus spp. detach
epithelial and underlying cells of their attachment area and sweep them toward the mouth. Heavy
infections with Ergasilus spp. can severely damage gill tissue, interfere with respiration, open the
way to secondary infection, and lead to death (Roberts and Janovy 2009). Although not in Lake
Ontario, fish mortalities caused by parasitic copepods have been reported by Schumacher (1952),
Allum and Hugghins (1959), Kabata (1970), and Rogers and Hawke (1978). Argulus spp., when
feeding and attached, cause severe localized damage to the integument of their hosts, and these
wounds may become secondarily infected with bacteria and fungi (Piasecki and Avenant-
Oldewage 2008). Achtheres spp. attached to the gill filaments can cause epithelial hyperplasia,
gill lamellae fusion, and partial or total loss of gill filaments (Piasecki and Avenant-Oldewage
2008).
Molluscs
The glochidia of Anondonta sp., Elliptio complanatus, and Lampsilis radiata siliquoidea have
been identified on the gills and fins of fish. Karna and Milleman (1978) reported that heavy
infestations of glochidia can result in early death of fish by asphyxiation.
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