Jellyfish Invasion: A Stinging Reminder of Overfishing and Climate Change

Aug 16, 2010· 1 MIN READ
A six-time grantee of the National Geographic Expeditions Council, Jon writes about all things ocean.

Jellyfish—those gelatinous, stinging, floating, pint-sized bogeymen of the ocean—are appearing this summer in increased abundance along coastlines around the globe.

Jellyfish do little more than float with the currents and sting anything they bump into. They offer painful evidence of just how badly we’re treating the ocean.

Jellyfish photograph beautifully; in real life, they are floating scum that bring pain to all they touch. (Photo: Dani Cardona/Reuters)

Over the weekend, jellyfish swarmed the Atlantic coast of Spain, stinging hundreds on a single day and sending scores of swimmers to the hospital. While most stings go away in a week or two, many still itch months later. Surgery is sometimes required to remove the affected area.

Jellyfish have been showing up in abundance along beaches in New York, France, Japan and Hawaii, stinging ocean lovers and clogging fishing nets.

Last year, more than 30,000 Australians were treated for stings, double the number treated the year before.

Formerly, such swarming happened very intermittently, and lasted just a couple of days. Now, jellyfish invasions are lasting for weeks.

In Spain this summer, a fishing boat from the Murcia region reported an offshore swarm of iridescent purple jellyfish spread over a mile.

"Those jellyfish near shore are a message the sea is sending us saying, ‘Look how badly you are treating me,’" jellyfish expert Dr. Josep-Maria Gili with the Institute of Marine Sciences of the Spanish National Research Council told the The New York Times.

Experts believe this stinging problem will only grow in years to come, the result of various environmental pressures bearing down on the ocean simultaneously:

1. GLOBAL WARMING increases sea surface temperatures, which encourage jellyfish growth, as does a corresponding lack of rainfall. Typically, freshwater from rain aggregates near shore and helps keep the jellyfish at a distance; lack of rain due to a changing climate—typical along the European coasts this summer—means jellyfish float closer to shore.

2. COASTAL POLLUTION reduces oxygen levels and visibility in the water, which scares most fish away from the shoreline. Jellyfish, however, thrive in these conditions. While most fish need to see to catch their meals, jellyfish filter food from the water, eating passively.

3. OVERFISHING eliminates natural predators of jellyfish like tuna and swordfish, which also allows for more plankton growth, which is inducive to jellyfish proliferation.

Some ocean watchers predict that in the not-so-distant future jellyfish will be the only marine life left, and may become a dietary staple. Savvy scientists, like the University of British Columbia’s Daniel Pauly, believe that we better start cooking up jellyfish recipes … and fast.

Eating jellyfish is already prevalent in some Asian countries, where sea cucumbers and sea urchins—“which live off dirt,” notes Pauly—are already on menus.

When Pauly first suggested the notion of jellyfish sandwiches, it was intended as a joke. Not today.

Can you say Goi Sua Tom Thit? The dish is found on menus in many Vietnamese restaurants, and translates as Shrimp, Pork and Jellyfish Salad.