Importance of the Guild Concept to Fisheries Research and Management

The concept of the guild has appealed to fisheries researchers and managers for simplifying analysis and assisting in the prediction of community change. Guilds have been developed based on reproduction, feeding, habitat use, and morphology. In most published accounts, guilds were used to describe a community change in response to some environmental perturbation (e.g., stream habitat modification or siltation). Members of a guild are often expected to react similarly to environmental change. However, little evidence exists to support the extrapolation of population changes in one guild member to that of other members of the same guild. It may be more reasonable to assume that the combined abundance 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 responds to environmental change in a more predictable manner than individual species. We recommend that guilds be developed based on critical environmental variables that are most influential in determining community composition. Also, the use of guild definitions needs to be evaluated with long-term data sets to ascertain their true ability to describe community dynamics.