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may partly be attributed to different periods in which data were collected. However, Trammel et al. (2002) similarly reported comparatively few captures of centrarchids in Grand Valley backwaters when seines were used during 1999-2001 (total of 729 centrarchids captured), the same period in which electrofishing removal efforts were conducted. Hence, the disparity in numbers captured may largely be attributable to gear type used. Indeed, Bundy and Bestgen (2001) and Trammel et al. (2002) reported that seines are an ineffective means to sample centrarchids in upper Colorado River backwaters. Electrofishing, specifically barge electrofishing, was found here to be a fairly effective means for capturing centrarchids: a total of 14,874 was captured during a three-year period, or 20 times the total captured by Trammel et al. using seines during the same time period. In addition, the habitats targeted by barge electrofishing included some backwaters that were seasonally isolated from the main channel and therefore would not typically be sampled during ISMP-type seining surveys. These habitats were more pond-like in appearance and may have provided better habitat for centrarchids than more typical backwaters open to the river and generally devoid of vegetation. The ISMP 1986-2001 seining catch rates suggest lower densities of centrarchids in backwaters during the 1999-2001 period than during the preceding year (1998). This could be interpreted as an indication that removal efforts from this project as well as those of Trammell et al. (2002) during the 1999-2001 period had a reach-wide depletive effect. However, catch rates of largemouth bass and green sunfish during the ISMP 16- yr period of record suggest relative abundance of both species often fluctuate by several orders of magnitude annually with or without removal efforts occurring (Fig. 9). Other variables therefore greatly influence densities, or seining catch rate, of these species in backwaters. Hence, it is difficult to draw cause-and-effect conclusions from the ISMP results regarding removal impacts on mean annual seining catch rates, and the question remains as to whether ISMP catch rates would have declined between 1998 and 1999 if removal efforts had not occurred. Based on barge electrofishing catch rates (mean number removed per backwater), no reach-wide depletive effect was evident from one year to the next during the three- year project. The absence of any noticeable depletion of largemouth bass and green 20