Laserfiche WebLink
• Reduced abundance of recruit-sized Colorado pikeminnow noted during this study may <br />be due to weak year-classes of age-0 Colorado pikeminnow in the past several years in nursery <br />areas of the middle and lower Green River. Trends in abundance of age-0 Colorado pikeminnow <br />were from ISMP investigations that sampled backwaters of the Green River in autumn since 1986. <br />• The population rate of change analysis showed a trend similar to that for ISMP <br />sampling from 1991 to 2003 and thus, was useful to track the trajectory of the population of adult <br />Colorado pikeminnow in the Green River Basin. Because this type of analysis requires consistent <br />sampling of the same locations from one year to the next, and can be accomplished with data <br />collected from only a single sampling pass, this analysis may be useful to document trends of <br />Colorado pikeminnow in the Green River Basin in years when the relatively intensive abundance <br />estimation sampling is not conducted. <br />• The ISMP catch/effort data showed a reasonably close and proportional relationship <br />with abundance estimates. <br />• Apparent reductions in abundance of adult and recruit-sized Colorado pikeminnow in <br />the Green River Basin may be related to low, drought-related base flows that began about the <br />same time this investigation began. The precise mechanism for the apparent reduction in <br />Colorado pikeminnow abundance and low flows is unknown. <br />RECOMMENDATIONS <br />• Continue with the sampling protocol for Colorado pikeminnow in the Green River <br />Basin as called for in the Recovery Goals. <br />60