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I~ I I- I I~ I I I I I I I I: I. I I I. I I, 12 occur over a period of 7 years (1974-1981) and across three investigative groups. Differences in gear type and sample variation confound any definitive trends in time, although the data suggest that the red shiner may be decreasing in numbers and the speckled dace increasing in the lower reaches. The Mt. Fuel Bridge station best illustrates this hypothesis; red shiners decreased froll1 93% of the catch in 1974 to 78% in 1978 to 57% in 1981. Conversely, speckled dace increased from 5 to 18% over the Stll:1e period. These variations in abundance may also be attributed to year class strength and cohort size. The spatial trends appear to be more defined than the temporal trends. As shown in ERI (1982), longitudinal trends in red shiners, speckled dace, flannel~outh suckers and roundtail chub appear to be a function of stream gradient and substrate. The lower 40 miles of the White River is dominated by a shifting silt/sand substrate that supports few macroinvertebrates for drift feeders like the speckled dace, flannelmouth suckers and roundtail chub. It does, however, provide backwater habitat for red shiners. The steeper gradient between RM 40 and RM 65 is associated with a gravel, cobble, boulder substrate that supports a more stable population of macroinvertebrates. This is reflected in greater numbers of the native and endemic species discussed above. Although the data presented in Figure 2 were taken primarily in late summer and fall, variations in species composition are evident. These variations reflect natural biological phenomenon controlled largely by the physical nature of the White River. River discharge often controls