The concept of the guild has appealed to fisheries researchers and man
agers for simplifying analysis and assisting in the prediction of comm
unity change. Guilds have been developed based on reproduction, feedin
g, habitat use, and morphology. In most published accounts, guilds wer
e used to describe a community change in response to some environmenta
l perturbation (e.g., stream habitat modification or siltation). Membe
rs of a guild are often expected to react similarly to environmental c
hange. However, little evidence exists to support the extrapolation of
population changes in one guild member to that of other members of th
e same guild. It may be more reasonable to assume that the combined ab
undance of all species in a guild can more accurately reflect changes
in their primary resource or a limiting factor. Thus, we suggest that
guilds reflect the characteristics of a super-species-a unit that resp
onds to environmental change in a more predictable manner than individ
ual species. We recommend that guilds be developed based on critical e
nvironmental variables that are most influential in determining commun
ity composition. Also, the use of guild definitions needs to be evalua
ted with long-term data sets to ascertain their true ability to descri
be community dynamics.