9463 - Laserfiche WebLink

Home Browse Search

r were from the spring stocking with an average TL of 112.0 mm (RCR=O.06) and four were likely from the 1998 releases (RCR=0.05). One fish had a 1998 PIT tag (TL=195 mm) and three had PIT tag scars with an average TL of210 mm. Seining conducted from Potash (RM 47.2) down to the Green River confluence in June yielded four bonytail stocked in 1999 and subsequent seining from July through August yielded another five individuals stocked in 1999. In the Green River, a total of 71 bonytail were collected during spring monitoring (Table 6). Electrofishing surveys produced eight bonytail. Four of these fish were from the spring stocking (RCR=0.02) and the other four were from the fall 1998 stocking (RCR=0.06). Forty-nine bonytail (average TL=94.1 mm) were collected between April 27 and June 10 during seining from RM 120.0 to 9.5. Fourteen bonytail were collected at RM 97 in fyke nets. Total lengths of three of these fish were: 193 mm,187 mm, and 175 mm. Total lengths of the remaining individuals averaged 103.7 mm. 2000 - On the Colorado River, electrofishing after the spring stocking found 93 bonytail (RCR=O.78). Spring seining yielded 61 (average TL=75.9) bonytail (Table 5). All of the fish collected in the spring were likely from the 2000 stocking based on their size. Electrofishing after the fall stocking found 170 bonytail (RCR=0.56), based on the mean recapture length (140.1 mm) and the proximity of the recaptures to the stocking site, it is believed these fish were from one of two cohorts (1999 or 2000) stocked in October 2000 (Table5). During spring seining on the Green River, 69 bonytail were collected (Table 6). Most of these fish were 20 to 30 river miles downstream of the stocking location and averaged 90.7 mm TL (109-55mm). However, twelve fish averaged 166.6 mm TL (218-140 mm) and were either from the 1998 cohort (mean TL=187.4) released in April 2000 or a 1999 release (Table 6). Spring electrofishing found none of the smaller cohort (1999) and 3 of the larger 1998 cohort (RCR=O.OI). Electrofishing after the fall stocking found 95 bonytail (RCR=0.69). Based on recapture lengths (average TL=90.0 mm), it is believed these fish were from the 2000 cohort stocked in October 2000 (Table 6). 2001 - On the Colorado River, electrofishing efforts in May yielded 65 bonytail (RCR=0.07). It is assumed that most of these fish were stocked in 2001. However, 12 fish were over 150 mm and potentially from a previous stocking (Table 5). Electrofishing in August resulted in no captures of bonytail. On the Green River, intensive electrofishing efforts for CPM population estimates in March-May yielded a total of244 bonytail (Table 6). The two sampling trips which preceded the spring stocking yielded 31 of these bonytail. These fish ranged in size from 68 to 256 mm, with an average TL of 97.7 mm. These fish were all stocked in 1999 or 2000. An RCR could not be estimated. The final two passes of the CPM population estimate in late May yielded the remaining 207 bonytail. These fish ranged in size from 70 to 315 mm, with an average TL of 102.7 mm. Eight of these fish were over 200 mm and likely from previous stockings, the remaining 109 were potentially from the 2001 stocking (mean TL=93.6 mm). However, the size range offish recaptured after overwintering demonstrates that TL is not a reliable metric when judging how 11