Jellyfish numbers are on the rise around the world, mostly as a result of overfishing according to jellyfish expert Ferdinando Boero, a professor of zoology at the University of Salento in Italy. “We are still hunters and gatherers, just as we were on land, and have overfished the ocean, creating a vacuum which is being filled by jellyfish,” Boero told the Underwater Times. “It’s not just happening in the Mediterranean but in seas all over the world.”
Thanks to overfishing, a majority of the jellyfish’s predators (tuna, shark, swordfish, moonfish and others) have been removed, creating a vacuum for jellyfish to thrive. Other factors giving rise to larger jellyfish populations include climate change and manmade alternatives to natural ecosystems.
Jellywatch.org provides information on worldwide jellyfish sightings, and is reliant on members of the public to provide reports by clicking on the “submit a sighting” button and filling out brief information. Created and maintained by scientist Steven Haddock and his colleague Katherine Elliott, the website not only provides an opportunity to submit jellyfish sightings, but sightings of other organisms as well, from red tides to vertebrates.
According to Professor Boero, monitoring jellyfish is not easy, because they cannot be seen from satellite. However, public reports are assisting scientists in tracking the patterns of the jellyfish. Just last year, more than 2,000 jellyfish sightings were recorded and this year’s records are higher.
Rising jellyfish numbers are a particular concern to tourist areas such as those on the Mediterranean coast, a traditional holiday spot for Britons where an influx of jellyfish could pose a serious threat to the well-being of swimmers and greatly reduce tourism dollars. The mauve stinger jellyfish caused more than 500 calls in a single day to French emergency services from tourists on a 10-mile stretch of the Mediterranean between Nice and Cannes in recent years, both from painful stings and swimmers reporting that they were surrounded by the species. The jellyfish’s sting can cause severe burns and sometimes scarring. From Australia to the Indo-Pacific region, an increasing number of people worldwide are being stung by jellyfish, with the most recorded cases in Australia. In the Philippines alone, the multi-tentacled box jellyfish causes 20 to 40 deaths every year. And the Americas have not escaped the sea jelly takeover. On September 25, 62-year-old endurance swimmer Diana Nyad was pulled from the water after being stung by a Portuguese man-of-war the day before. Her swim from Cuba to Florida was cut short two-thirds of the way to her destination.
These large organisms also cause problems for fisherman when they clog nets, making it more difficult to fish.
And the jellyfish problem is not easily remedied. Boero said he would like to see cooks use jellyfish as a food source, adding that they are a delicacy in China and Japan. “…If we don’t do anything about the situation all the indications from Jellywatch suggest that the Mediterranean is moving towards a gelatinous future, just like the rest of the seas of the world,” Boero said.