Jelly brained journalist
Shame your journalist couldn't manage to take this story a bit more seriously. The main reason for the rise of the jellyfish is that overfishing is causing the collapse of whole marine ecosystems. The only thing left in these deadzones is jellyfish. With no predators left and no competition for resources jellyfish populations boom out of control.
Hope you like the taste of jellyfish - it's the only seafood you'll be getting in twenty years time.