7270 - Laserfiche WebLink

Home Browse Search

3 in the Colorado squawfish holding tanks. Colorado squawfish seemed to lack sufficient motivation to feed when tested singularly (trials A-C, Appendix) and were therefore tested in groups of three. They also appeared to lack interest in channel catfish as prey items (trials D-G, Appendix); hence, only those fish that would eat catfish with their spines removed (CCSPL) were exposed to catfish with their spines intact (CCSP). The experimental pro- tocol was as follows: The Colorado squawfish to be used in a particular feeding trial were starved for 5 days before the trial. On the morning of the trial they were transferred to the experimental aquarium and allowed to recover from handling stress and acclimate for 6-7 hr. The 40 catfish to be used in the feeding trial were tranquilized with tricane methane sulfonate and quinaldine and measured. On the morning of the trial dorsal and pectoral spines were clipped and fish were placed in a recovery aquarium for 5-6 hr. This method of spine removal evidently has no apparent effect on the prey (Reist, 1980). The CCSPL were released in the experimental aquarium with the Colorado squawfish in the late afternoon at a time when squawfish are nor- mally fed. They were observed for the first 0.5 hr and then left with the squawfish for 90 hr. The catfish were fed during this period, but not the Colorado squawfish. On the morning of the fifth day the Colorado squawfish were removed from the aquarium, after which the catfish were removed and counted. If any had been eaten, the remaining catfish were tranquilized, remeasured, and then returned to the recovery aquarium. Colorado squawfish used in the trial were placed back in experimental aquarium and left alone until the afternoon. If any CCSPL had been eaten, then 40 catfish with spines intact (CCSP) were placed in the aquarium. Fish were observed for 0.5 hr after introduction and left together for another 90 hr. After feeding