Laserfiche WebLink
in the main channel could also provide competition for young razorbacks learning to survive <br />in the riverine environment. White suckers should be removed from the Gunnison River <br />when encountered during routine sampling. <br />CONCLUSIONS <br />Objective 1: Evaluate standard techniaues for efficient removal of nonnative predators. <br />Shoreline electrofishing was effective at capturing northern pike for removal from the <br />Gunnison River near Delta. Because of lack of reproduction and its small size, the northern <br />pike population in the Gunnison River can be controlled with mechanical means. The <br />population occupies a small area that can be effectively sampled with relatively Little effort. <br />Limited sampling can capture enough pike to substantially depress the population if efforts <br />are directed at time periods when northern pike are most vulnerable. Based on this study, <br />shoreline electrofishing when river flows are between 85-113 mils will be the most effective <br />sampling technique. <br />Green sunfish and black bullhead were the only other predators collected during this <br />study. Because these species are common in the Gunnison River and are actively <br />reproducing in the Delta area, controlling their populations will be considerably more <br />difficult than northern pike. Although sampling with traditional methods (e.g. electrofishing, <br />trammel and fyke nets, seining) can remove large numbers of these species, their populations <br />will quickly rebound because of their high reproductive potential. Control of these species <br />will require use of piscicides or water Level manipulation in floodplain habitats where they <br />are most common. Control of these (and similar) species is currently being addressed by the <br />pond reclamation program already funded by the Recovery Program. <br />Objective 2. Estimate relative decline in nonnative predators as a result of fish removal. <br />Based on change in catch rate (both electrofishing alone and all gears combined), <br />numbers of northern pike declined notably in the Gunnison River in 1995 and remained low <br />16 <br />