Estimating drivers and identifying uncertainties in smallmouth bass population dynamics in an invaded river network

Smallmouth bass (Micropterus dolomieu) is an important recreational
sportfish and destructive non-native species when introduced into
freshwater habitats. There is therefore a need to understand the drivers
of, and uncertainties in, smallmouth bass population dynamics for various
management objectives. We combined long-term smallmouth bass catch-effort
and early life history data from a non-native population in the Green
River sub-basin of the upper Colorado River to develop a demographic model
that links interannual variability in environmental conditions to
recruitment in three river reaches. We used the model to quantify how
hydrology, river temperature, and exploitation drive smallmouth bass
population dynamics. Early life stages were influenced by timing of
hatching and discharge. Dispersal of age-0 fish and density-dependent
dynamics were identified as primary sources of uncertainty. Determining
the true nature of density-dependent dynamics is important, as the impact
of exploitation-based management actions is dependent on the strengths of
any density-dependent feedbacks. Our model provides a framework to predict
smallmouth bass population responses to future climate conditions,
reservoir operations, and exploitation levels.