摘要：We quantified the ontogenetic and seasonal diet shifts of smallmouth bass (Micropterus dolomieu) in Baron Fork Creek, an Ozark stream in northeastern Oklahoma. Age-0 smallmouth bass (<125 mm TL) consumed primarily baetid mayflies, and sub-adult and adult smallmouth bass (≥125 mm TL) consumed primarily cyprinids and crayfish. Stomach fullness of age-0 smallmouth bass did not differ statistically among seasons, but it was highest in spring and lowest in fall and winter for larger smallmouth bass. Baseline logistic regression explained the diet of smallmouth bass well and quantified the switch from insects to fish and crayfish at approximately 125 mm TL. The model also showed that diets differed among seasons. Insects always dominated diets of age-0 smallmouth bass, but the stomachs of larger smallmouth bass were more likely to contain fish in spring, contain fish and crayfish in summer, and be empty in late-fall and winter. Although smallmouth bass primarily switch from microcrustaceans, to insects, to fish and crayfish as they grow, bass of all sizes maintain the ability to forage within and among major taxonomic groups (insects, fish, crayfish) and adapt to the temporally variable populations of prey communities in north temperate streams.
