Demography of an Imperiled Minnow Species (Lepidomeda aliciae: Leuciscidae) Under Different Predation Regimes

To understand the demography of an evolutionarily naïve fish species that sometimes coexists with an invasive predator, we collected mark–recapture data and size–frequency data of two populations of southern leatherside chub (Lepidomeda aliciae), one of which coexists with nonnative brown trout (Salmo trutta). For each population, we estimated vital rates from mark–recapture data to inform a stage-structured matrix transition model. We also used size–frequency distributions from these populations in an integral projection model. Southern leatherside chub from the predator-free environment exhibited higher survival (except age-0) and lower average realized fecundity than the population from the predator environment. Survival rates of age-0 in the predator environment were double the rates in the predator-free habitat. Growth transitions from the smallest size class and reproduction at medium sizes had a combined elasticity of nearly 0.70 in the predator environment, but only 0.43 in the predator-free population. Our results indicate that the southern leatherside chub in Lost Creek that are sympatric with invasive brown trout have reduced abundance and survival of larger individuals and higher age-0 survival and value of reproduction at smaller sizes, compared to the Salina Creek population.