The lake responded faster than anyone imagined. Dormant seeds of aquatic plants sprouted as the water cleared and sunlight penetrated the depths. By the spring of 1994, water plants covered 97 percent of Christina's surface. The number of canvasbacks soared from 15 in 1984 to 68,000 in 1993. The DNR has also used rotenone on several dozen small northern Minnesota lakes to remove white suckers.
Biologists then stock the water with rainbow, brook, or brown trout.
Though the suckers don't do root up the lake bottom, removing them provides the trout with a competition-free environment where the stocked fish can grow up to 6 pounds. Not entirely popular Native fish proponents have criticized the DNR for rotenone use, saying that invertebrates and native fish species are casualties of the fish kills. But DNR biologists argue that most rehabilitated lakes are so degraded that few species of fish remain other than carp and bullheads. And enough of all existing species survive the rotenone treatment to eventually repopulate the lake. Biodiversity, they say, can actually be enhanced by the ecological improvements that result from the rough fish removal.