Surges in jellyfish populations may be one reason for a drop in fish stocks observed in the Mediterranean and Black Sea, according to a new report published by FAO.
Overfishing, which removes top predators from the sea, is one of the factors behind jellyfish “blooms”, or suddenly increased numbers. A “vicious circle” can then follow in which large numbers of medusae feed on fish larvae and juveniles , and “further reduce the resilience of fish populations already impacted by overfishing,” according to the report, from FAO’s General Fisheries Commission for the Mediterranean.
Jellyfish “might be the proverbial straw that broke the camel’s back” says the Review of Jellyfish Blooms in the Mediterranean and Black Sea.
Normally, only the impact of human fishing activities is taken into account in setting sustainable fishing limits, the report says. But jellyfish can also have a high impact on fish eggs and larvae, either directly or by competing for the same food sources. They should thus be considered in any ecosystems-based approach to fisheries management.