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Eco-Terrorists Without Backbones - Jellyfish Swarms Threaten Fish Prisons

April 22, 2003

Eco-Terrorists Without Backbones - Jellyfish Swarms Threaten Fish Prisons


The British Newspaper "The Guardian" is reporting on an invasion of jellyfish into the Shetland Islands of Scotland. Paul Brown, a reporter for The Guardian, described the jellyfish as terrorists of the deep. The April 9, 2003 headline was "Jellyfish Swarms Terrorizing Britain's Fish Farms."

Quotes from The Guardian story prefaced by "TG". Sea Shepherd Conservation Society editorial prefaced by "SSCS".

On the positive side of this issue, the jellyfish are causing serious financial ruin to the loathsome fish farms of the Shetland Islands.

TG: Silently, in their millions, they begin to appear. No one knows where the swarms come from or why - but come they do.

SSCS: Apparently the bulk of the jellyfish invasion is made up of the common sea jelly, sometimes called the saucer or moon jelly.

This species is being assisted by a smaller unidentified jellyfish that act like the "special forces" for the jellified horde. These smaller jellies sting on contact. The imprisoned salmon, unable to escape, are literally driven insane by the stings and dash themselves against the nets, sustaining serious injuries.

The moon jellies that do not sting, drift into the cages and clog up the gills of farmed fish, literally choking them to death. Another species of larger jellyfish also "attack".

TG: The death toll of farmed fish may measure in the millions. Drifting with the currents, they create solid walls of jelly round the cages, preventing fresh water from flowing in. This can leave the fish in oxygen-starved water, effectively suffocating them.

"The effects on individual farmers can be catastrophic," says David Sandison, general manager of the Shetland salmon farmers' association. "It can mean a total loss for a fish farm if a swarm appears. There are thousands and thousands of them."

SSCS: The Guardian describes the jellyfish as a plague:

TG: The problem with these plagues of meandering jellyfish is that we know so little about them. Jellyfish are ancient creatures, which live a bizarre and complicated lifestyle, but they have been largely ignored by science. Since they are not eaten and are of no economic value, they have been left unstudied since Victorian times.

SSCS: And then The Guardian reports that the Jellyfish have gone too far and are deserving of our attention because now they are the cause of loss of profits.

TG: Now, all that is changing: jellyfish are losing us money, and jellyfish studies are back on the agenda. These creatures are threatening not only our fish farms, but also tourism - [no one] wants to swim among piles of jellyfish washing up - and knowing so little makes it very difficult to guard against them.

SSCS: As is typical of human responses, a task force has been mobilized. Ten universities and fish research institutions have been recruited by the European Union to launch a three-year "study".

TG: Their first task is to understand the lifestyle of these translucent predators, and then try to control them or at least predict what they will do next.

SSCS: The fish farmers are calling for an early warning system to protect their captive fish from being destroyed. The farmers are talking about installing pumps to send oxygen into the holding pens during jellyfish attacks. The experts are at a loss to explain the invasion. Per the Guradian story, one scientist said:

TG: "Some of the species we are noticing now have not been recorded before. Are they exotic species possibly brought to these waters in the ballast water of ships? They appear to have bred somewhere out there in the Atlantic or perhaps they have always been here and we did not notice."

A secondary problem is that the swarms may be associated with algal blooms, those vast mats of algae that create brilliant strips of colour in the oceans when viewed from space. The blooms drift in from the Atlantic, probably feasting on nutrient-rich waters brought up from the depths beyond the continental shelf. How they fit in with the jellyfish is unclear, but investigating these blooms is another part of the 2.5 million Euro project.

SSCS: The jellyfish have not restricted their attacks to the Shetlands. Other areas being "invaded" are:

TG: Limfjorden in Denmark, an area of 1575 sq km, which used to be an important fishery. Jellyfish are being blamed for eating the eggs and larvae of early-spawning fish such as flounders, plaice and cod. Overfishing in the past has damaged the fishery but scientists are trying to discover whether the multitude of jellyfish is preventing the recovery of the rest of the ecosystem.

A third area is the Mar Menor lagoon in Spain - separated from the Mediterranean by a 20km sandy barrier - which has shallow inlets and is an important tourist area. The lagoon traditionally supported an important fishery of grey mullet, sea bream and prawns but stocks have plummeted. Jellyfish have always been present but two species, unrecorded until 10 years ago, have appeared. The large scyph-omedusae jellyfish underwent a population explosion in 1993, a phenomenon that has been repeated every summer since.

The final study area is Lurefjorden in Norway, known for its massive population of coronate scyphomedusa jellyfish. This is the top predator in the fjord and the new project aims to discover what environment and water conditions have allowed this to happen.

SSCS: "It is amazing to me," responded Captain Paul Watson of the Sea Shepherd Conservation Society, "that people are so mystified by these occurrences. The fact is we are rapidly changing the entire ecological balance of our oceans because of over-fishing, pollution, and misguided predator management. For every action taken by humanity affecting our oceans, the oceans react. Remove one predator and a niche is made available for another that had previously been in a less dominant position. Fishermen kill seals because they eat fish. This lowers the seal population and opens up a niche for other predators, and not all predators have teeth, and some are just plain microscopic."

Captain Watson also pointed out, "a major predator of jellyfish are sea-turtles, and sea-turtle populations have been dramatically diminished. Less sea-turtles, more jelly fish."

And finally commenting on the devastation to the fish farms, Captain Watson said, "the sooner these fish farm abominations are removed from the marine eco-system, the better. Fish farms are ecologically destructive, and I'm backing the "spineless troops" with the hope that they will cause extreme economic damage to the salmon farming industry."

This Invasion is Not Restricted to North Sea - Jellyfish "invasions" are happening worldwide.

In the Gulf of Mexico, a Louisiana shrimper reported, "There's miles and miles of them. I traveled all the way from Half Moon Bay past the Gulfport ship channel, and I couldn't throw my nets over once."

Many of the world's ecologically compromised waters, from the Antarctic seas to tropical lagoons, are being inundated by these invertebrates. In 1999, enough jellyfish to fill 50 trucks were sucked from the ocean by the cooling system of a power plant in the Philippines. The creatures shut down the plant, plunged 40 million people into darkness, and started rumors of a coup d'état. In Japan, power plant staffs have been preventing similar blackouts by collecting jellyfish that accumulate near the intake pipes. But so massive are the globular hauls that their rancid odor makes area residents sick.

This is of course just another sign of humanity's increasing pressure on marine eco-systems. As fish are depleted, the invertebrates have less competition for plankton. Jellyfish also thrive in oxygen-depleted waters where fish cannot survive.

The meek may be finally taking over the oceans, with the help of the babbling ape who lives on land and wages war on the sea.


 

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