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1 larvae did not appear related to sampling effort for 1996 to 1998 when data were available for all taxa. In 1992 to 1999, a total of 60,977 fish were captured using all sampling gear types. Of those, 31,999 (52.5 %) were sucker larvae, and 1,808 (3.0 %) were razorback suckers. From 1993 to 1998 when light traps were used consistently and full samples were retained, the number of catostomid larvae captured varied from 106 in 1997 to 13,386 in 1994. Capture rates of catostomid larvae did not appear related to sampling effort for 1993 to 1998 (r = - 0.15). The CPUE for all native suckers and for razorback sucker larvae was highest in 1994 by a considerable margin (Table 6). The CPUE for razorback sucker was relatively low in 1995 and 1997 to 1999. The proportion of razorback sucker larvae to all catostomid larvae was relatively high in 1993 and 1994 but also declined after that (Fig. 7). Razorback sucker larvae were relatively rare in samples collected from 1996 to 1999. Number of razorback sucker larvae captured varied by more than an order of magnitude (12 to 174), in spite of the relatively even numbers of samples collected (126 to 247) and a relatively constant (1,115 to 2,158) number of sampling hours among years. Sampling effort and number of razorback sucker larvae captured were not positively correlated (r = - 0.10) as the highest level of sampling effort conducted in 1999 captured only 121arvae. Larvae were relatively small in 1997 and 1998; average size in those years was 11.6 and 12.5 mm TL, respectively (Table 7). No lengths were taken on larvae captured in 1999 because those fish were sent to the Ouray National Fish Hatchery. Timing of captures of razorback sucker larvae were relatively late in the middle Green River from 1997 to 1999, ranging from 2 June to 1 July (Fig. 8 ). Back-calculation of spawning dates based on captures of larvae suggested that spawning occurred from early May to early June 17