Modelling population viability in fragmented environments: contribution to the conservation of an endangered percid (Zlngel asper)

摘要

Zingel asper is an endemic percid of the Rhone catchment. The demography and habitat use of this endangered benthic species have been studied in previous works. The species exhibits natural low densities and clumped distribution related to habitat distribution. Based on these results, the authors build a stochastic equations network model, integrating spatial structure at intrapopulation level and vague density dependence. Calculation of density, growth rates, and local extinction rates globally match the field results. The numerical sensitivity analysis on extinction probabilities shows that adult and juvenile survival rates and spawning success (due to random events) are the key parameters of intrapatch dynamics. Low negative variations in these parameters increase extinction probabilities. The number of available connected patches and the dispersal rate drive the population persistence at the interpatch scale. Population extinction probability over 100 years is at least 0.4 for dispersal rate below 0.2, or when the number of connected patches is below 15. These results enlighten the role of dispersal in nonmigratory fish populations and should be useful in assessing the impact of riverine habitat fragmentation through river-damming and habitatloss.