Walleye (Stizostedion vitreum vitreum) eggs were incubated in a temporary jar hatchery using Rainy River water taken below paper mills discharging sulfite, kraft, insulating board, and groundwood wastes. Eggs were also incubated in trays held on and off the bottom in the river below mills, above the mills, and in tributary streams. In two years, survival of eggs in jar controls was 31.2 to 73.5 percent. Survival to hatching of eggs jar-incubated in polluted water was 0.02 to 6.0 percent. At river stations below mills survival of tray eggs on bottom did not exceed 1.2 percent; and off bottom, 3.5 percent. Eggs held on bottom above mills had maximum survival of 37.6 percent; and off bottom, 49.1 percent. In most experiments in polluted Rainy River water the principal cause of mortality was Sphaerotilus growths on the eggs which prevented successful emergence of fry. Prior to hatching, egg-survival rate in jars was similar in controls and in experiments. Chemical treatment to remove slime increased hatch of eggs. Sphaerotilus-covered eggs removed to fresh water lost the bacterium and hatched at a high rate. Some bottom deposits below mills were toxic to eggs.
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Smith et al. (1963) studied this question.