The success of smallmouth bass (Micropterus dolomieu) is affected by temperature regimes. Concepts are presented for evaluating the suitability of alternative temperature regimes through experimentally derived data, including ultimate incipient lethal temperatures and maximum weekly average, short-term maximum, and final preferendum temperatures. Also, concepts are described for basing evaluations on temperature tolerances for periods including spawning, egg and larval incubation, growth, and winter survival in the first year of life.