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. Topock . Laughlin Rainbow trout Striped bass Smallmouth Largemouth Bluegill Redear Catfish Bullhead Carp Razorback Flannelmouth t:. I -. - - -. I o 0.5 1 1.5 2 2.5 Fishf100 square meters 3 3.5 Figure 1.3. Comparison of catch per unit effort (fish/lOO m2) of fish taken from the Colorado River by 3.7-em inner panel trammel nets set near Topock Gorge (RM 27-40) and the Laughlin area (RM 62-82). Native Fish Three native species were captured during this study; the bonytail, flannelmouth" sucker, and razorback sucker. All three species have been stocked. The following section describes our findings. Bony tail Only one bonytail was captured during the study. It was taken near Bullhead City and represented the first capture in this region in nearly three decades. Approximately 18,000 bonytai1 have been stocked in Lake Havasu. The species must be considered extremely rare, representing only 0.0 125% of the fish captured during this study. Telemetry studies in Lake Mohave, suggest that bonytail prefer deeper canyon habitats (Marsh and Mueller, 1999). It is quite possible these fish are remaining further downstream in Lake Havasu were we did not sample but there is also evidence that survival may be poor. We were contacted by a fishing guide from Lake Havasu City that informed us that one of his clients had caught a 5.4 kg striped bass near Blakenship Bend. When the fish was dressed, they found its stomach contained 6, 25 cm long bonytail. Flannelmouth Sucker A total of 766 flannel mouth suckers were PIT -tagged, the vast majority being taken upstream of Bullhead City Park (RM-71). Flannelmouth suckers appeared to be concentrated from Davis Dam downstream 30 Ian. Most (90%) flannelmouth suckers were captured during their spawning season (January through May), where fish were routinely taken at the Boy Scout Camp jetty and in the mouth of Laughlin Lagoon. Most suckers (73%) taken near Laughlin Lagoon were females. A large school of suckers were typically observed just upstream ofthe lagoon's entrance. Their numbers would swell to >200 fis!I during the spawning season. Presumed males were positioned along the bottom and were loosely dispersed (1 m) at depths >2 m. The substrate within this school had many discolored or lighter areas where it appeared the bottom had been recently disturbed. We observed actual spawning acts that caused clouds of detritus to be flushed from the 10