They’re not exactly fun to swim with and they don’t taste very good, but if we don’t stop overfishing the world’s oceans, jellyfish may come to dominate the sea. Their numbers are swelling thanks to decreased competition from fish.

Currently, giant Nomura jellyfish measuring over six feet in length and weighing up to 440 pounds are growing in numbers in oceans around the world, especially Southeast Asia, the Black Sea, the Gulf of Mexico and the North Sea.

The problem is so bad that researchers have tried controlling the populations using sound waves to explode the creatures, as well as using special nets that cut them into pieces.

Humans have such a strong appetite for fish that we’re removing too many from the oceans too quickly, leading to imbalances in delicate ocean ecosystems. Fish eat small jellyfish and also compete with them for food such as zooplankton. Without enough fish around, jellyfish are left to multiply.

And multiply they have. Researchers say the problem is made even worse by nitrogen and phosphorous runoff, which causes oxygen-starved ‘dead zones’ in which fish can’t survive – but jellyfish can.

The CSIRO Marine and Atmospheric Research team says we’ve got to stop overfishing and control the transport of jellyfish around the world to prevent oceans from being dominated by the slimy, tentacled sea creatures.

Though jellyfish burgers have been suggested as a solution, that won’t help in this particular case. Nomura jellyfish have too many stinging cells to be eaten.