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<br />e <br /> <br />8 <br /> <br />e <br /> <br />Table 1. (concluded). <br /> <br />Variable <br /> <br />Assumption and sources <br /> <br />VlO <br /> <br />White suckers utilize pools for resting after negotiating <br />obstructions during migration and spawning (Stewart 1926; <br />Dence 1948). larval white suckers feed in quiet eddies and <br />gentle currents (Stewart 1926); adult white suckers are pri- <br />marily pool {nhabitants (Propst 1982b) and seek out pools for <br />cover (Stewart 1926; Raney 1943; Dence 1948; Nelson 1968). <br />Streams without pools are suboptimum and streams with 40% to 60% <br />pools are considered optimum. <br /> <br />Vll <br /> <br />It has been reported that lacustrine populations spawn on sand <br />or gravel shoals subject to wave action (Reighard 1913; Hayes <br />1956; Olson 1963) and that the highest larval densities were <br />found over sand and sand/gravel substrates in littoral regions <br />(Krieger 1980). It is assumed that optimum lentic spawning <br />substrate is coarse sand and/or granule gravel. Large pebbles <br />and boulders or silt substrates are poor. Medium sand or small <br />pebble substrates are good to fair. <br /> <br />17 <br />