A Leslie matrix model for Sicyopterus lagocephalus in La Réunion: Sensitivity, uncertainty and research prioritization

• A Leslie matrix model captures the dynamics of amphidromous fish in La Réunion.
• Plausible parameter values are consistent with a stationary population.
• Model survival rates are extremely low while fecundity rates are extremely high.
• Survival in rivers and fecundity rates are the most critical parameters.

We propose a Leslie matrix model for the population dynamics of Sicyopterus lagocephalus in La Réunion. In order to capture both the amphidromous and the seasonal natures of the species’ life history the model has four stages (sea + three river sites) and is cyclical with a 12 month period. Baseline parameters (age-specific fecundity, spatial dispersion patterns and survival rates) were chosen in such a way that the dominant eigenvalue of the year-on-year projection matrix is 1. Large uncertainties on the parameter values preclude the use of the model for management purpose. A sensitivity/uncertainty analysis sheds light on the parameters that cause much of the output to vary and that are poorly known: the life expectancy in rivers and the mortality both at river mouths and during the drift of larvae to sea. The aim is to help policymakers and researchers prioritize data acquisition efforts. The ultimate goal is a sustainable management of Sicyopterus lagocephalus in La Réunion.