Dangerous Drifters

From New York to Namibia, to Ireland, Japan, Australia, and the Philippines, jellyfish numbers are exploding, closing beaches, shutting down nuclear plants, invading floating fish farms, ruining fishing nets, and injuring swimmers. The biomass of jellyfish is now greater than that of fish in some of the seas that were once considered the best commercial fishing zones in the world .

The Black Sea is one of those 'used-to-be', important commercial fish producers, with great economic value for the people of the countries bordering its shores: Turkey, The Ukraine, Georgia, Russian and Bulgaria. However, in the 1980s, the carnivorous jellyfish Mnemiopsis, arrived via ocean tanker ballast water. Finding conditions ideally suited for their wants and desires, they immediately set up housekeeping and began to take over the the polluted waters. Within a few years, there wasn't enough space left for the sturgeon and other fish species, and the fishing industry collapsed.

Similarly, the fishing grounds off the Namibian coast, which used to be gorged with sardines, anchovies, and pilchards now contain a fish biomass of less than 3.6 million metric tons, while the number of jellyfish has grown to over 12.2 million tons. Meanwhile, the Sea of Japan has become plagued with a steady steady stream of five million, giant 450 pound Nomura's jellyfish, pouring in from the China Sea every day during the months of September and October. In America, the Gulf of Mexico hosts large swarms of jellyfish that are often so dense they contain more jelly than water.

One of the most bizarre incidents occurred off the north coast of Ireland in November 2007, when a swarm of jellyfish 10 miles square and 35 feet deep, invaded Ireland's only fish farm In Glenarm Bay, Cushendun, off the County Antrim coast. Billions of fist-sized mauve stingers drifted over the cages like some thick red tide, stinging to death or suffocating the entire stock of more than 120,000 adult salmon.

John Russell, head of the Northern Salmon Company farm, said the fish were destined for Christmas sales to high-end caterers in Britain. The loss was estimated at $2 million, wiping out the company's cash flow until the following fall, when young fish at their Red Bay site were big enough for market. However, the stingers popped that bubble a couple of days later, when they drifted into Red Bay killed those fish too.

Russell said he ordered three 35-foot boats into the area in attempt to salvage some of the fish, but they were unable to get through the jelly. “We were absolutely helpless to do anything,” he said.

"One of the difficulties with the Glenarm site is the strength of the tide," a fisheries officer told reporters. "The tide pulled in the jellyfish and the water cannot move through the cages. The fish were asphyxiated because they have no water moving through the cages to bring oxygen."

It is hard to imagine a mass of jellyfish packed together so tightly that they act like a single monstrous creature ten miles in diameter (twice the size of the city of Vancouver, Canada) and thirty-five feet deep.

Unusual concentrations of the mauve stinger jellyfish, Pelagia noctiluca, are common off Spain's Balearic Islands, as well as elsewhere in the Mediterranean. In fact, they show up on most of Europe's popular beach resorts in August every year, stinging thousands of bathers. While not lethal, the stings are extremely painful. Peppering the burning area with meat tenderizer seems to ease the pain somewhat. Urine, which is an oft-recommended home remedy, can actually heighten the pain.

Pelagia noctiluca grows up to 10 centimeters wide, and is sometimes also called the nightlight jellyfish because it produces a blue-green luminescent mucus, most often seen as a glow in ships' wakes at night. But its more common name, mauve stinger, reflects the species' most noticeable effect on people.