Publication Abstract

Interactions between jellyfish and marine fish and fisheries: insights into fisheries sustainability.

R.D. Brodeur, W.M. Graham, H. Mianzan, C.P. Lynam*, S-I. Uye and M.J. Gibbons

Evidence is accumulating that gelatinous zooplankton populations have increased recently in many regions of the world and are widely considered as indicators of ecosystem health. Jellyfish are generally detrimental to fisheries because they feed on zooplankton and ichthyoplankton, and so are both predators and potential competitors of fish, and because they interfere with fishing directly. Possible benefits of jellyfish to marine fish include provisioning of food for some species and providing shelter for juvenile stages of several fish species. There is also a relatively minor human benefit in that jellyfish are commercially fished and consumed in several societies, mostly in Asia. However, the negative effects are thought to greatly exceed any positive ones and the effects of jellyfish population outbursts on ecosystems and the economies that depend on them can be profound. These include direct predation on early stages of marine fish and competition for food with older stages of fish. These effects have been examined through field studies, controlled laboratory experiments, and estimated using quantitative ecosystem models. Jellyfish blooms also directly impact commercial fisheries directly through filling or clogging trawls and fouling fixed gear and aquaculture net pens, resulting in enormous losses worldwide on an annual basis. Given the propensity of fisheries to fish at successively lower trophic levels as top predators are removed (fishing down the food web), there is a potential for fisheries to transition to more gelatinous target species in the future. Our paper focuses on empirical field, laboratory or modeling studies that examine the effects jellyfish have on marine fish species and fisheries and how they are incorporated into ecosystem functioning from diverse ecosystems of the world’s oceans.