Laserfiche WebLink
<br />1 <br /> <br /> <br />I <br /> <br /> <br />I <br />1 <br /> <br />1 <br /> <br /> <br />r <br />I 1 <br /> <br /> <br /> <br /> <br />River based on mark/recapture data from standardized monitoring. The latter numbers used <br />conventional population estimate models and are probably more accurate than Tyus (1991). <br />The Interagency Standardized Monitoring Program (ISMP) (USFWS 1987), developed to monitor <br />trends of Colorado squawfish population fluctuations, began in 1986 as part of recovery efforts for <br />this species. The most recent summary of trends over the last decade demonstrates that catch rates <br />are at or near highest levels since monitoring began (Figure 1). How these values compare to <br />historical densities is unknown. They may be due to increasing capture efficiency, a sustained peak <br />in normal demographic fluctuations, or an actual increase in Colorado squawfish numbers in <br />response to recovery efforts. <br />Adult Cdorado Squawfish ISM? <br />/ t <br />I <br />l <br />as 87 q 90 91 92 93 94 95 96 <br />MG CO LG <br />Figure 1. Results of the interagency standardized monitoring program (ISMP) for adult Colorado <br />squawfish from the three populations 1986-1996. MG =Middle Green River; CO = Colorado <br />River; LG = Lower Green River. Catch per effort was calculated as fish collected for an how of <br />electrofishing. <br />Razorback sucker Historically, razorback sucker ranged throughout the Colorado River Basin in <br />large mainstem, warmwater reaches. Currently, two relict populations exist in artificial <br />impoundments in Arizona and three natural populations occur to some extent in the Upper <br />Colorado River Basin, particularly the Green River. Limited reproduction has been documented in <br />11 <br />