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?+,40 <br />treated water for several days. If they survive, the <br />water is safe for restocking. Analytical techniques can <br />also be used to determine how much rotenone is still <br />present. <br />Q. How often are treatments made? <br />A. Although treatments are usually 99 to 100% effec- <br />tive, rotenone rarely kills every fish. Occasionally, <br />some areas cannot be effectively treated. In general, <br />the benefits from treatments will last for 5-15 years; <br />most are good for about 10 years. <br />Q. How soon can we expect fishing to improve after a <br />rotenone treatment? <br />A. Fish stocking can begin as soon as biologists deter- <br />mine that it is safe to re-introduce fish. Generally, <br />small fish are stocked because they are cheaper. This <br />means more can be stocked but a longer time will be <br />required for them to grow to catchable size. Depend- <br />ing on the growing season, most waters will have <br />good fishing within 2-3 years after treatment. As a <br />general rule, aquatic invertebrate populations return <br />to pre-treatment levels within several months to one <br />year. <br />Q. What about residue levels in killed or survivor fish? <br /> <br />A. Rotenone in dead, dying or surviving fish degrades at <br />about the same rate as that in the water. Surviving