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FEASIBILITY OF DEVELOPING AND MAINTAINING A SPORT FISHERY IN THE SALT RIVER PROJECT CANALS Figure 16. Overall length-frequency distributions of yellow bass in the Arizona Canal (October 1992-July 1994). Figure 17. Overall length-frequency distributions (across seasons) of roundtail chub in the Arizona Canal (October 1992-July 1994). Granite Reef Electrical Barrier Monitoring To estimate fish immigration into the Arizona Canal, we looked at fish collection data from surveys (Jakle and Riley, unpubl. data) taken between Granite Reef Dam and the electric fish barrier. From 1991 to 1995, 17 fish species were collected above the barrier (Table 9). Species richness remained relatively stable, with a low of 9 species collected in 1991 and a high of 13 species in 1992 and 1995. Percent species composition varied across years. The most abundant species (n 700) collected above the barrier for the 5-yr period were: desert sucker (29.70/6), tilapia (Tilapia spp.; 16.5%), Sonora sucker (14.10/6), channel catfish (13.0%), and common carp (12.4%). The least abundant species (n < 50) were: roundtail chub, walleye, threadfin shad, bluegill, yellow bullhead, white amur, and bigmoutlr buffalo (Ictiobus cyprinellus). Percent species composition of tilapia and common carp were highly variable between years. In 1991, tilapia was the most common species collected (n = 748) but they were absent from the 1995 survey. However, tilapia still ranked second in overall relative abundance during this 5-yr period. Common carp above the barrier were rare to nonexistent between 1991 and 1993, but their numbers increased in 1994 (n = 526) ranking them highest in abundance. In the 1995 survey, carp numbers again declined, but they still ranked fifth in total abundance for the 5-yrs. The abundance of both species above the barrier was unusual when compared to our electrofishing sampling downstream where carp were rare (n = 19) and tilapia were absent. Experimental Fish Stockings Channel Catfish (June-Stocking). Most June- stocked catfish sampled were recovered within the first 5 weeks after stocking (Fig.18). We sampled 161 (10.7%) fish from June 1993 through July 1994. Monthly and repeated-effort electrofishing surveys captured 44 June-stocked channel catfish. Twenty of these fish were collected during our repeated-effort sampling (CPUE = 1.7 fish/hr). We sampled 69 June-stocked channel catfish by angling (CPUE = 1.1 fish/hr) and 1 fish by gill net (CPUE = 0.1 fish/hr). We documented an additional 41 fish harvested by public anglers, but were unable to estimate the catch rate due to 60 cn ................. L 40 LL 0 = 20 Z o 1 4 10 13 16 19 22 25 26 31 34 Weeks After Stocking 3i 4u 43 49 52 55 Figure 18. Recapture frequency of June-stocked channel catfish across weeks after stocking for all sampling methods (June 1993 - July 1994). 32 ARIZONA GAME & FISH DEPARTMENT, TECH. REP. 18 B. R. WRIGHT AND I. A. SORENSEN.1995