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Why was this BUI originally listed as impaired?
- These deformities can be caused by pollution and sediment contamination.
- Pollution discharges from the heavily urbanized and industrialized shorelines of the river have contributed to fish tumours and other deformities in fish species. Pollutants such as polycyclic aromatic hydrocarbons (PAHs) have accumulated in the sediment and waters, causing tumours and other deformities in various fish species.
- Research in the 1980s indicated that there was an elevated incidence of liver tumours in Detroit River fishes.
- External lesions or deformities are not a good indicator of contaminant exposure; hence, liver tumours are the focus of this BUI.
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This BUI will be considered to be ‘not impaired’ when….
Incidence rates of liver tumours in brown bullhead (aged 3-5 years) are not statistically different than the Great Lakes background rate (2%).
What was done?
- 2020 Assessment of Fish Tumors and Other Deformities (BUI #4) in the Detroit River Canadian Area of Concern: Brown bullhead (3-5 yrs of age) from the upstream Detroit River (Peche Island) did not have any liver tumours (0/28 fish). Tumour prevalence (i.e., the proportion of the population with a given characteristic) in these fish was not significantly different from reference sites in the Detroit River (i.e., sites that have been exposed to only small amounts of contaminants). Brown bullhead (3-5 yrs of age) from the midstream and downstream sites (Turkey Creek and Bois Blanc, respectively) had 1 fish with a liver tumor (1/84 fish or 1.2%). There was no significant difference in tumour prevalence between these fish and fish at reference sites.
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When did the status change?
- The status changed to not impaired in December 2020
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The bi-national connection: What is the U.S. doing?
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Where can I learn more?
Detroit River Canadian Remedial Action Plan: Stage 2 Report (2010): pages 68-76.
Factsheet – Re-designation of the Fish Tumour and other Deformities Beneficial Use Impairment
Assessment of Fish Tumors and Other Deformities (BUI #4) in the Detroit River Canadian Area of Concern
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