According to many scientists, the world’s oceans are suffering from a giant surge in the population of jellyfish.  The huge numbers of these creatures is not only crowding other fish in the sea but it’s also creating big problems for humans too.

In 2007, jellyfish around Northern Ireland eliminated an estimated 700,000 salmon in the country’s sole salmon farm.  Many people lost their jobs as a result.  The fishing industry in the Black Sea was destroyed in 1982 when jellyfish were introduced to the region. More recently, a Japanese fishing vessel tipped over into the water when it caught a full net of huge Nomura jellyfish in 2009.  The tourist industry has also run into problems because of them.  Holiday-makers are sometimes unable to enjoy beautiful beaches in places like Australia due to the large population of deadly “box jellyfish”.  These jellyfish can seriously harm or even kill a human because of their poisonous sting.

The reason for the sudden expansion in jellyfish populations in recent years is not entirely understood.  Humans are partly to blame for this problem.  For example, salmon and sea turtle populations, the natural enemies of jellyfish, are now dangerously low in some places due to overfishing.  This has allowed the jellyfish population to grow unusually large.  Scientists are only beginning to find other reasons for this jellyfish boom but it may be too late to stop them from dominating the world’s oceans.