Smallmouth Bass Feeding Dynamics and Growth in Headwater Streams of the Interior Highlands

Smallmouth Bass have been extensively studied, but knowledge of the effects of temperature and hydrologic regime on populations in the Interior Highlands of Arkansas remains lacking. In 2018, I monitored diet characteristics of Smallmouth Bass, located in streams prone to dryness and representing a range of water temperatures, and presence of potential competitors. Diet characteristics of Smallmouth Bass, Green Sunfish, and Creek Chub were studied in the Boston Mountains ecoregion of Arkansas during the summer of 2018. In 2019, I expanded the scope of the project to search for relationships between Smallmouth Bass growth and hydrologic regime. My objectives were to compare growth rates of Smallmouth Bass among three ecoregions and to characterize the relationship between hydrologic regime and annual growth rates of Smallmouth Bass. I sampled Smallmouth Bass from five streams each in the Boston Mountain, the Ouachita Mountain, and the Ozark Highland ecoregions of Arkansas during the summer of 2019. Annual growth was estimated for each captured fish by measuring annuli on the whole otolith and then the sectioned otolith for individual fish deemed age-2 or older. Individual annual growth was significantly affected by both flow and age. I found an inverse relationship between the coefficient of variation of flow and individual annual growth of age-2 Smallmouth Bass from 2014 through 2018. Fluctuations in hydrologic regime may be influencing predatory success or evolved strategies of Smallmouth Bass in our study. Climate change could cause increases in stream temperatures and hydrologic fluctuations which may alter metabolic costs and prey availability. Thus, focusing on why Smallmouth Bass annual growth decreases with fluctuations in mean flow should be a primary concern for future studies in the Interior Highlands of Arkansas