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Table 5. (concluded). - Variable Assumptions and source VIJ Pool depth is important as cover (Stewart 1926). Pool depths at which white suckers are commonly found (60 tl' 90 cm) (Propst 1982b) are considered optimum. Very shallow depths (< 25 cm) are considered poor and very deep pools were assumed to contribute to a good to fair habitat because white suckers are found at varying pool depths in streams (Thompson and Hunt 1930; Propst 1982b). Deeper pool depths are usualJy not considered a habitat detriment because the white sucker inhabits many depths in lacustrine habitats (Reighard 1913). VI4 Shade is an indication of cover and streams with ~ 50% shade are considered excellent. Thompson and Hunt (1930) and Dence (1948) report that suckers are commonly found in shaded portions of streams. Unshaded streams are assumed to be poor to fair depending on other cover available. VIS White suckers reach maximum abundance in low to moder- ate gradients (Stewart 1926). Since Propst (1982b) failed to find white suckers where there was no flow, very low gradients (< .5 m/km) were considered poor. Very high gradients (> 25 m/km) were also considered poor because white suckers appeared to have trouble maintaining equilibrium in turbulent waters (Symons 1976). Minckley (1963), Curry (1979), and Hocutt and Stauffer (1975) reported on white suckers occupying streams with gradients of 1.2 to 13 m/km, which are considered excellent to fair, respectively, as the gradient increases. e VI6 White suckers are common in pools with slow to moderate velocities (< 40 cm/sec), but Minckley (1963), and Symons (1976) most frequently found adult white suckers at velocities of 10 to 19 cm/sec which were assumed excellent. As mentioned in VIS' turbulent velocities (Symons 1976) or zero velocities (Propst 1982b) are considered poor. VI7 Suckers have been reported to successfully spawn after migrating up to 6.4 km (Oence 1948). Spawning habitat up to these distances, without known obstructions, are considered excellent. It is assumed that longer distances would be progressively less suitable. 34 e