Because of natural complexity, field studies are often
inconclusive with regards to the ultimate cause of a given change observed
in wild animal populations. As a consequence, there is scope to develop an
Experimental Ecology Approach (EEA). In this paper, we favour the use of
experimental ecology studies to evaluate the effects of environmental
factors on fish biology. We identify the advantages of EEA: disentangling the effects of
several factors and identifying their respective roles, generating
artificial scenarios and increasing our capability to collect and analyse
data. This study emphasises the constraints of this approach: fish
biological performances may be altered by rearing conditions, by
domestication and by the prevention of some behaviours. It also considers
the extrapolation of experimental results with regard to the sea including
the realism of experimental design and the constraints of scaling or
extending the results to larger scales.
We also propose some experimental ecosystems which are well adapted to the
requirements of EEA and a careful selection of fish species which fit this
approach very well. Atlantic Cod (Gadus morhua) is identified as a good candidate for
experimental studies and we present examples of the contribution of EEA to
the description and quantification of the effects of environmental factors
in this species. We conclude by highlighting the respective contribution of
field studies (describing a situation in the wild and suggesting some
possible causes) and EEA (allowing an active investigation of phenomena and
identifying their final causes).