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Table 4. Depth (meters) and velocity (meters/sec) of winter habitat used by radiotagged adult Colorado squawfish in the Green River and Yampa River (from Valdez and Masslich 1989, Wick and Hawkins 1989). Green River Fish Yampa River Fish Wirrter 1 Winter 2 Winter 1 Winter 2 Fish Species D V D V D V D V Colorado squawfish Backwaters 1.09 0.03 0.8 0.3 0.7 0 0.6 0 Embayments - - - - 0.7 0 0.6 0 Eddies 1.16 0.03 1.4 0.1 2.1 0 0.8 0.01 Runs 1.16 0.24 1.3 0.2 0.7 0.2 0.7 0.12 Pools - - - - 2.1 0 0.8 0.01 Average--> 1.16 0.18 1.3 0.2 1.2 0.1 0.7 0.03 Razorback sucker Backwaters - _ _ _ _ _ _ _ Embayments _ _ _ _ _ _ _ _ Eddies 1.37 0.03 1.3 0.1 - - - - Runs 1.37 0.34 1.2 0.3 - - - - Pools _ _ _ _ _ _ _ _ Average-> 1.37 0.18 1.2 0.2 - - - - variety ofhabitats--including eddies, pools, backwaters, and embayments--the fish used backwaters and embayments exclusively. They also noted that Gish in main channel habitats (eddies and pools) moved more frequently, and hypothesized that this movement was because these habitats failed to provide fish with a full complement of ovenvintering needs. Advantages to using off-channel habitats (backwaters and embayments) were noted as (1) low velocity for energy conservation, (2) greater concentration of food, (3) easier identification of home range through visual or olfactory cues, and (4) protection from mobile frazil ice. Off-channel habitats may also provide other indirect benefits, such as increased oxygen and primary production. Adult Colorado squawfish in the Yampa River used microhabitat similar to that used by the Green River fish. Wick and Hawkins (1989) determined that the fish most frequently used 0.6 to 1.1 m depth in backwaters, embayments, runs, and shorelines. Highest frequency of effective depth (depth of ice-free water) was 0.3 to 0.6 m. Total depths used in eddies ranged from 1S to 2.9 m, _ 28