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ST. LAWRENCE INFO
Pathological Problems in Lake Whitefish in the St. Lawrence River
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Lake Whitefish |
Examinations performed on Lake Whitefish in the St. Lawrence River pointed up the presence of pathological problems in this fish, whose range stretches from Canadian fresh waters to the U.S. Great Lakes. A total of 545 specimens of whitefish were caught in the St. Lawrence River in 1996 for histological analyses of various tissues and organs. Individual organ analyses revealed malignant liver tumours in 42 individuals, a prevalence rate of 7.7%. The tumours were present in individuals of at least 430 mm long and aged six years or older. This study also found:
- six hermaphroditic fish (1.2%);
- 11.7% of female fish (26 of 223) had ovarian anomalies;
- 8.2% of male fish (22 of 267) had testicular anomalies;
- average concentrations of various contaminants in liver, including polychlorinated biphenyls (PCBs), chlorobenzenes, pesticides and trace metals, were six to eight times higher in specimens of whitefish than in three other fish species (i.e. Channel Catfish, White Sucker and Walleye) caught at the same site.
The weight-to-length ratio — the condition factor — of Lake Whitefish in this study was lower than was noted 40 to 50 years ago at this same location and lower than observed in intact environments in the Great Lakes region of the U.S.
The presence of malignant liver tumours, ovarian and testicular lesions and a declining condition factor in whitefish in the St. Lawrence River could be related to elevated concentrations of toxic chemicals in the tissues of this fish.
Due to its longevity, its benthivorous diet and its large range, the whitefish can be used as an indicator species of environmental contamination. The present study was based on an examination of about a dozen different tissues taken from more than 500 specimens. It is one of the most exhaustive studies ever undertaken on the state of health of a species of fish in the St. Lawrence River, and provides a baseline level for possible future monitoring programs.
Literature
Mikaelian, I., Y. de Lafontaine, J. Harshbarger, L. Lee, and D. Martineau. 2002. Health of lake whitefish (Coregonus clupeaformis) with elevated tissue levels of environmental contaminants. Environmental Toxicology and Chemistry 21(3): 532–541.
Related Links
Fisheries and Oceans Canada – Lake Whitefish
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