BIOMANIPULATION - THE NEXT PHASE - MAKING IT STABLE

Review of the literature on biomanipulation shows that fish manipulations have occurred through the following methods: piscivore addition; piscivore catch restriction; habitat enhancement; piscivore removal; planktivore exclusion; planktivore removal by selective catch, lake emptying, fish poisons, fish diseases, winterkill, summerkill; habitat expansion or contraction; planktivore addition; and natural events. The methods can be classified as deliberate, inadvertent, or natural, all of which have successful and unsuccessful examples. However, the problem of perpetuation of successful results remains unsolved. It is proposed that this may be resolved through use of a refuge or refuges from among the following: low light intensity refuge; low temperature refuge; low dissolved oxygen refuge; physical concealment refuge; visual clutter refuge; behavior modification refuge; and predator inefficiency refuge. Perhaps through use of such mechanisms large herbivorous zooplankters can continue to exist in lakes. Examples are given. © 1990 Kluwer Academic Publishers.