Population Dynamics of Three Benthic Chub Species (Macrhybopsis spp.) of the Lower Missouri River

Macrhybopsis spp. populations, specifically Shoal (M. hyostoma), Sicklefin (M. meeki), and Sturgeon (M. gelida) Chub have declined recently within Missouri River Basin. To increase our understanding of reasons for this decline, we developed population models and a population viability analysis for each of these three species due to increasing threats from predation and habitat loss and a recent increase in our understanding of their reproductive life history. For each species, we developed an age-structured population matrix model with hierarchical stochasticity, which partitions the total variance for a parameter into sampling and temporal components and applies them at the appropriate levels in the model. Under the current state of knowledge about their life history, we found that populations of all three chub species should increase over time and that population dynamics are most sensitive to length-at-age and age-specific survival rates. However, current survival estimates have large temporal variance; consequently, more precise estimates of survival are needed. To better understand chub population dynamics in the Lower Missouri River, future research needs to address knowledge gaps relating to environmental impacts on growth and survival.