7202 - Laserfiche WebLink

Home Browse Search

t Results of electrofishing surveys conducted during May and June of 1986- 1988 indicate that certain areas in the 15-mile reach may be concentration points for many Colorado squawfish and razorback sucker of the Grand Valley during spring runoff. During this time in 1986, the number of squawfish caught or seen per hour of shocking in the 15-mile reach was approximately 3.2 times that caught or seen in the adjacent 18-mile reach of river immediately downstream; in 1987, there was approximately 6.1 times as many caught or seen per hour. In 1988, however, 1.5 times as many squawfish were caught or seen per hour in the 18-mile reach as were in the 15-mile reach. Thus, in two of three years the electrofishing success rate was higher in the 15-mile reach. The combined data indicated relative abun- dance during spring runoff was about 2.0 times higher in the 15-mile reach th th d l an e a jacent ower reach (Fig. 2 and Appendix; Table 4). The number of razorback suckers shocked in the 15-mile reach during the three years was about 5.9 times larger than in the lower 18-mile reach (Fig. 2). Although relatively little sampling effort was expended in the Gunnison River below the Redlands Diversion in spring 1987 and 1988 (no effort in 1986), there were three Colorado squawfish caught or seen during 3.8 hr of shocking; this rate was considerably higher than that for the other two adjacent Colorado River reaches (Fig. 2). During our July and August electrofishing efforts in the lower Gunnison in 1987, Colorado squawfish E were either caught or seen at rates of 2.00 and 2.23 fish per hour (Table 2). Almost all of these captures or observations were made in the plunge pool of the Redlands Diversion Dam, the use of which by squawfish dropped off entirely in September. Many squawfish seem attracted to a 1.3-mile 10 1 1