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! into the adjacent river reach by either mechanical removal from the controlled side channel, or by allowing them to escape through a fish control structure. Prior to release, fish would be enumerated, vital statistics recorded, and presence of the PIT tag verified. 41 Numerous inactive and active gravel pits located along the upper Colorado River, particularly in the greater Grand Valley, constitute unnatural riverine features. Some of these pits are completely isolated from the river by large dikes whereas others communicate with the river during high flow in the spring. Razorback sucker have used these off-channel habitats during spring and are probably attracted to these areas because water temperatures are warmer than that of the adjacent river. These gravel pits are usually deep, open areas and may be more detrimental than beneficial to razorback sucker for several reasons. First, razorback sucker may become stranded in pits that are diked from the river as flood waters recede. Second, if razorback sucker spawn in these ponds, the eggs and young would be vulnerable to predation from introduced predators such as largemouth bass (Micropterus salmoides) and green sunfish (Lepomis cyanellus) which are often abundant in such ponds. Valdez and Wick (1981) recommended that gravel pits be permanently diked from the river. Valdez and Wick (1981) also suggested enhancing man-made gravel pits to benefit razorback sucker and other native fishes. Such ponds, might be useful in the recovery of razorback sucker. Sloped gravel pits that flood during spring runoff and drain naturally as flows recede may benefit native fishes such as razorback sucker by providing feeding, resting, and possibly spawning areas while minimizing potential establishment of non-native predaceous fishes. Ponds diked from the river could be used as rearing units for 26 i