About ten years ago, the ctenophore, Mnemiopsis leidyi, first appeared in the Black Sea. This ctenophore was previously found only on the eastern seaboard of the Americas, so it was probably transported to the Black Sea in the ballast water of ships. Since then, it has multiplied enormously, causing a drastic decline of several important fisheries. One possible reason for its profound impact in the Black Sea is that the ctenophore has no predators there, since the fish fauna is extremely limited. Therefore, in collaboration with Russian and Ukrainian scientists, this Small Grant for Exploratory Research project will develop a plan to study the feasibility of introducing fishes from the Americas that specifically feed on Mnemiopsis. These scientists are ware of the dangers of introducing exotic species, and recognize the need for a general agreement as to the advisability of such a course from all of the nations in the region. However, before any such proposals can be put forward, basic information on the feeding behavior and environmental tolerances of such fishes is necessary. This project represent the first step in the American part of this research program. Basic information on feeding preferences of fishes will be obtained by interviews with local fishermen along the eastern seaboard of the Americas, and with laboratory studies on feeding preference. Methods will be developed for the mass culture of Mnemiopsis in the laboratory. Dr. Harbison will also determine the ability of these American ctenophore-eating fishes to survive in the specialized environmental conditions of the Black Sea. This research will provide the first step in trying to solve a major case of biological pollution, and will serve as a model program for international cooperation in dealing with other forms of introduced marine species.