Decrease in Mercury Content of Fishes in Ball Lake, Ontario, Since Imposition of Controls on Mercury Discharges

摘要: Weight, fork length, and white muscle mercury concentrations of walleye (Stizostedion vitreum vitreum), northern pike (Esox lucius), lake whitefish (Coregonus clupeaformis) from Ball Lake, northwestern Ontario, were compared for 1971, 1972, 1976. The had received 1962 to 1970; since then there have been increasingly rigorous controls. Adjusted mean at the group length 444 mm 1.99, 2.71, 1.39 mg/kg, respectively, three sample years. Corresponding values 594 mm long 5.05, 5.72, 1.80 mg/kg. Whitefish 1972 1976 0.62 0.42 441 mm length. changes are discussed in relation decreased input it is suggested that suspension may be a controlling factor. Key words: contamination, walleye, pike, whitefish, Lake