Interactions of pelagic cnidarians and ctenophores with fish: a review

Medusae, siphonophores and ctenophores (here grouped as `pelagic coelentera tes') interact with fish in several ways. Some interactions are detrimental to fish populations, such as predation by gelatinous species on pelagic eg gs and larvae of fish, the potential competition for prey among pelagic coe lenterates and fish larvae and zooplanktivorous fish species, and pelagic c oelenterates serving as intermediate hosts for fish parasites. Other intera ctions are positive for fish, such as predation by fish on gelatinous speci es and commensal associations among fish and pelagic coelenterates. The int eractions range from beneficial for the gelatinous species (food, parasite removal), to negative (predation on them). We review existing information a nd present new data on these topics. Although such interactions have been d ocumented frequently, the significance to either fish or pelagic coelentera te populations is poorly understood. The effects of pelagic coelenterates o n fish populations are of particular interest because of the great importan ce of fisheries to the global economy. As fishing pressures mount, it becom es increasingly important to understand how they may influence the balance between pelagic coelenterates and fish.