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RESULTS <br />Selective control of undesirable fish is generally defined <br />as actions taken by aquatic managers to reduce numbers or <br />negative impacts of these species within aquatic communities. <br />This reduction does not have to be complete removal, but may be <br />manifested on temporal, spatial, population, and/or community <br />scales (Figure 1). A successful selective-control project <br />requires that negative impacts are reduced and corresponding <br />positive responses from desired species are documented. <br />Selective-control projects have occurred on a variety of <br />spatial or biological scales. Most chemical treatments are on a <br />small spatial scale such as treatment of small ponds, lakes, or <br />streams to remove undesirable species (e.g., Clemens and Martin <br />1952; Spitler 1970; Stefferud et al. 1992). However, some <br />chemical-treatment projects have been on large spatial scales. <br />For example, the treatment of Strawberry Reservoir (4,873 ha, <br />300,000 acre-ft) and associated valley streams (259 km) (Lentsch <br />et al. in press), and the treatment of the Green River (716 km) <br />in 1962 before the closure of Flaming Gorge Dam (Binns 1967) were <br />intended to remove fish species on a community level. <br />Selective-control projects also can focus at a population <br />(single-species) level. For example, Peters (1961) eliminated <br />80% of the population of gizzard shad Dorosoma cepedianum'in a <br />Texas lake by rotenone application with only a small percentage <br />of other fish being killed (also see Rose and Moen 1953; Hulsey <br />17