Suspended sediment effects on walleye (Sander vitreus)

Environmental windows are seasonal restrictions imposed on dredging operations in the Great Lakes and other waterways of the United States. Such restrictions often generically assume that sediments resuspended by dredging result in adverse impacts to fish; this is the case in western Lake Erie where the environmental window was established due to potential impacts on walleye (Sander vitreus). To address this concern, laboratory studies mimicking sediment resuspension during dredging operations in western Lake Erie were conducted to determine whether suspended sediments affect walleye eggs and fingerlings. Newly laid eggs and 45- to 60-d old fingerlings from separate hatcheries were exposed for 72-h under flow-through conditions to 0, 100, 250, and 500. mg/L total suspended sediment (TSS). Fingerlings, eggs, and newly hatched larvae were analyzed for multiple lethal and sublethal endpoints. Data indicated no significant effects of suspended sediment on egg hatch success or fingerling survival after three days of exposure. No significant differences were observed when comparing percent egg viability in the control with any TSS treatment; however, a downward trend was observed at 500. mg/L. No significant differences were observed during comparisons of fingerling gill lamellae in the control with any TSS treatment; however, a statistically significant difference was observed when comparing gill lamellae in the control with the original supply animals. No significant differences were found between control means and unexposed eggs or any TSS treatment. These effect data for walleye will serve to better inform the setting of environmental windows for this species in western Lake Erie.