INCOMPATIBILITY OF COMMON LAKE MANAGEMENT OBJECTIVES

ABSTRACT

Lake management involves the formulation of objectives, not all of which are compatible in a given water body. Common objectives such as high quality water supply, suitability for contact recreation, and pleasing aesthetic properties are generally associated with low plankton standing stock, especially as regards phytoplankton. On the other hand, production of fish for food or sportfishing is often impaired by decreases in plankton biomass. Strong correlation has been found between measures of plankton production or standing stock and fish yield. Investigated relationships between phytoplankton, zooplankton, planktivores, and piscivores are consistent with an energy pyramid model of the pelagic food web; greater production at the top of the pyramid is caused by a corresponding increase at its base or through increased internal energy transfer efficiency. Management for higher energetic efficiency is in its infancy and that for greater plankton biomass conflicts with other management objectives. Division of responsibility among various organizations and agencies of government may help achieve single objectives, but impedes progress toward a unified systems approach to lake management. Management objectives may be less conflicting for poorly aerated systems or where fishery management is aimed at certain target species, but serious consideration should be given to potential conflicts during goal formulation. Lake associations and managers should establish management priorities early in their planning processes. Their decisions should use expertise from both fishery and water quality science.