Both “warmwater” and “wadeable” are terms of convenience without precise definition and are used by biologists to describe streams that are generally too warm to have sustainable salmonid populations and can be safely traversed by walking (i.e., a section of stream should have the majority of its length less than 1 m deep, and it should be possible to cross in chest waders in nearly all areas). Warmwater streams in North America are estimated to provide more than a half-million kilometers of fishable waters and many times that amount of waters containing fish (Rabeni and Jacobson 1999). Warmwater streams have experienced a surge of attention in the past three decades because of increased sportfishing opportunities due to point-source pollution abatement and because of the popularity of using fish assemblages as indicators of biological integrity for regulatory and management purposes. At least 38 states have fish bioassessment programs in place (USEPA 2002).

Sampling fish in warmwater streams is usually done for one of two reasons: (1) to evaluate a targeted species (e.g., sport fish or endangered species), or (2) to evaluate the entire fish assemblage. Thirty-two species of sport fishes, as defined by state and provincial agencies, occur in warmwater streams. The most popular are largemouth bass, smallmouth bass, spotted bass, striped bass, muskellunge, northern pike, walleye, several catfishes, and common carp. Important species regionally are rock bass, pumpkinseed, bluegill, white crappie, black crappie, other sunfishes, white perch, yellow perch, chain pickerel, buffalo, other suckers, and freshwater drum.