A hierarchical zero‐inflated Poisson regression model for stream fish distribution and abundance

Ecologists are frequently confronted with the challenge of accurately modelling species abundance. However, this task requires one to deal with both presence/absence as well as abundance. Traditional Poisson regression models are not adequate when attempting to deal with both issues simultaneously. Zero‐inflated regression models have been proposed to deal with this problem with much success. We extend these models to incorporate both a multilevel hierarchical structure and spatial correlation. The model is illustrated using a dataset concerning the Hypseleotris galii (Fire‐tailed Gudgeon), a native species to eastern Australia.