Physical habitat modelling for fish - a developing approach

Abstract

Quantitative physical habitat modelling is a river management methodology that has been developed to aid the assessment of the impacts of altered river discharge on freshwater aquatic communities. In this paper we outline the potential value of habitat modelling in advancing the study of fish (particularly 0+ fish) habitat use, and also issues surrounding the inclusion of young fish in environmental impact assessments. Young fish have often been used as target species during such assessments, due to their perceived sensitivity to environmental changes, particularly associated with altered river discharge. However in the past, the paucity of information on young life stages, combined with the general difficulty in quantifying their habitat requirements has limited the use of habitat models for this purpose. Firstly we describe the context within which habitat modelling has been applied traditionally: the development of water resources, and the predictive assessment of associated environmental problems. Alternative approaches to habitat modelling are briefly mentioned. Overall, these techniques, which combine physical and biological data offer a broad perspective for the ecological management of degraded rivers, and can assist in developing our understanding of the processes that influence aquatic organisms in running waters. In the 20 or so years since its inception, habitat modelling has undergone considerable improvement. However there has not been a recent review of such advances. Therefore in the main text, we describe the current state of habitat modelling, emphasising recent developments. Many of these offer possibilities for the advancement of our knowledge of 0+ fish.