The main objective of our study was to develop a temperature-dependent age-class Leslie matrix model, based on experimental field data, in order to predict short and long-term population dynamics of a bullhead population in the Bez River network (Drôme, France), for example in view of water temperature fluctuations. Bullhead, a cryophilic species rarely manipulated by humans, is known for its sensitivity to temperature [1] and is thus an appropriate model organism to study the impact of temperature. For the purpose of our model, the Bez River network was divided into six sampling sites differing in their thermal conditions. Local temperatures were recorded at all sampling sites in the river. Census was annually performed between 2002 to 2008 providing body length data, while fecundity data were available for 2002 and 2003. The demographic model parameters (fecundity, survival rates) were then calibrated from part of this experimental data (2002 to 2004). Fecundity was directly related to body length by an allometric equation. Adult survival rates were estimated from data of successive years and were in agreement with values provided in the literature. Juvenile survival rates were modelled using a density-dependent function and larval as well as juvenile dispersion processes between sampling sites were taken into account. We validated our matrix model by predicting the population dynamics in the Bez River network for the years 2005 to 2008 and compared the simulation results to the experimental field data of this period. In order to calculate the age-dependent fecundity, we computed the body lengths of the simulated age classes by using a temperature-dependent von Bertalanffy growth function [2], since previous studies have already shown that temperature had an impact on growth and thus also on reproduction [3]. A global uncertainty analysis was performed by taking into account the uncertainty of all model parameters simultaneously. It allowed us to quantify the uncertainty of the model outputs.