Natural and anthropogenic perturbations do not always equally affect all pa
rts of an ecosystem, and all parts of an ecosystem do not equally contribut
e to maintain fish communities. The increasing pressure to use natural reso
urces and to modify habitats led to the development of approaches to identi
fy areas of key importance for fish communities. Following these approaches
, aquatic systems could be perceived as puzzles, composed of a multitude of
pieces with temporally flexible physical attributes and biological roles.
Such a spatially explicit framework requires models that may allow one to p
redict fish distribution patterns and fish net energy gain once they have a
dopted a specific distribution pattern. Despite the conceptual appeal of sp
atially explicit approaches, functional tools may be obtained only after th
eir assumptions have been tested and their models have been validated. Effo
rts must be deployed to identify temporal and spatial scales at which fish
distribution and abundance should be estimated and modeled. Studies on fish
behaviour and the energetic consequences of these behaviours must be condu
cted to insure that bioenergetic criteria used to define fish habitat quali
ty do not depend on arbitrary assumptions about fish activity costs.