9443 - Laserfiche WebLink

Home Browse Search

1 1 Downstream of the San Rafael River in the Labyrinth Canyon reach of the Green River, most sampling was near Anderson Bottom and Millard Canyon. Effort at individual sites or reaches varied among seasons and years due to differences in flow level and availability of suitable sampling areas so effort by sites was not reported. Adult sampling was with fyke and trammel nets in low-velocity channel-margin eddies, large backwaters or pools, and flooded tributary mouths. These gears were thought less harmful than electrofishing capture of ripe adults over the spawning areas as was previously done (Muth 1995, Modde et al. 1996). Sampling began in late April to early May and usually extended through mid- to late June, thus encompassing most of the reproductive period for razorback suckers (Tyus and Karp 1990, Muth et al. 1998). Fyke nets were set for 1 to 3 days each; trammel nets were set for 1 to 3 hours each. Additional data obtained outside of the Basinwide sampling program were used in analyses of the status of razorback suckers in the middle Green River. Those data were from the Interagency Standardized Monitoring Program (McAda et al. 1993 to 1997), the Levee Removal Program (Birchell et al. 2001 draft), other flood plain sampling (Modde 1997), and from 1998 and 1999 efforts aimed specifically at capturing adult razorback suckers for brood stock for the Ouray National Fish Hatchery. Boat electrofishing and passive gear such as trammel and hoop nets were used in those efforts. Broodstock collection involved springtime electrofishing of spawning bars near Escalante Ranch, the primary sampling location for data analyzed by Modde et al. (1996). Sampling at the spawning bar had not been conducted from 1994 to 1997 due to potential injury to reproducing adults. These additional data were collected in the same reach encompassed by Basinwide sampling, so we assumed that the same population was at risk of capture for all sampling. 4