8176 - Laserfiche WebLink

Home Browse Search

identified, measured, weighed, and released. The net was set frequently in 1996, but it was used only twice in 1997 due to higher discharge. Collapsible minnow traps were set in slack water areas in 1996. The traps measured 10 x 10 x 17 inches with 1/16-inch mesh. Traps were anchored to shore in a position that allowed fish access to openings on both ends of the net. Dry dog food was used as bait, and set times ranged from approximately 1.5 to 17 hours. All fish captured were identified to species and enumerated. A subsample offish was measured and all fish were released. Capture efficiency of minnow traps was low and discharge was higher in 1997 than in 1996, which reduced the number of slack water areas. Therefore, minnow traps were not used in 1997. Light traps (Southern Concepts) were set in backwaters in 1996. These traps were 12.5 inches high, 9.5 inches in diameter, and had 4 mm-wide openings. Traps were set overnight, and all fish captured were preserved in alcohol so that they could be identified at a later date. Light traps were not used in 1997 due to their poor efficiency in 1996 and the lack of backwater habitat observed in 1997. Fine-mesh drift nets were set in slow runs for periods ranging from 10 minutes up to several hours. The length of time the nets were set depended on the amount of debris carried in the water. All material collected in drift nets was preserved in alcohol and transported to the lab for sorting and fish identification. Fish Tagging In an effort to collect information on the growth and movement of suckers, 561 flannehnouth suckers and 94 bluehead suckers were tagged in 1997 with T-bar anchor tags or fingerling tags (Floy Tag and Manufacturing, Inc.). Four of the tagged flannelmouth suckers were recaptured on the same day as their initial capture, and 2 were caught the day after their initial captwe. Four of these six fish were remeasured when they were recaptured. This limited data set provided a way to check the precision of measurements of total length, standard length, and weight, based on the assumption that the actual values for these parameters did not change enough to be noticed in the short time between capture and recapture. Radio tags were used to collect data on the movement of Colorado pikeminnow. Three Colorado pikeminnow captured by boat electrofishing were implanted with radio transmitters produced by Custom Telemetry and Consulting. These radio tags weighed 20 grams and had internal coiled-loop antennas. Four other Colorado pikemi?mow (three caught with electrofishing gear, one caught in a hoop net) were implanted with radio transmitters produced by Advanced Telemetry Systems. These tags also had internal coiled-loop antennas, and weighed from 14.52 to 20 grams. Transmitters were never implanted in fish unless the weight of the transmitter was less than 2% of the individual's body weight. Upon capture of a Colorado pikeminnow large enough to receive a radio transmitter, the fish was anesthetized with tricaine methane sulfonate (Finquel brand of MS-222). The transmitter was inserted in an incision made along the side of the fish in a position that was anterior to the left pelvic fin. This location was used so that the transmitter would not rest upon the incision. Fresh water was administered to the gills of the f sh during the operation. Alcohol was used as a disinfection agent, and saline solution was used to remove residual alcohol from the transmitters and prevent irritation of exposed tissue. After the transmitter was placed in the body cavity, the incision was stitched with absorbable chromic gut sutures. No antibiotics were 5