North Sea lobsters' surprising appetite for jellyfish revealed

Jellyfish could be a 'huge' food source for one of the North Sea's most commercially important catches, scientists have said, after filming a lobster feasting on the species usually considered a pest.

A lobster eating a jellyfish, Picture: Heriot-Watt University/PA Wire

A team from Edinburgh’s Heriot-Watt University was surprised to find lobster scaring off other marine life in order to eat helmet jellyfish carcasses which had been attached to an underwater camera and lowered into the Sognefjorden in western Norway.

The experiment was designed to find out which deepwater species were most attracted by a jellyfish dinner, with hagfish and amphipods expected to be interested.

But it was the Norway lobster – worth around £80 million to Scottish fishing catches – that was most keen and ate half of the jellyfish.

Scientists said it could sustain lobster for three months and the experiment raises questions about the place of jellyfish in sustainable commercial fishing.

Dr Andrew Sweetman, associate professor of marine benthic ecology in the Lyell Centre at Heriot-Watt, said: “We had no idea Norway lobster fed on the jellyfish carrion that sinks to the depths, so it was very exciting to capture this on camera. The Norway lobsters’ feasting was fast and furious.

“In both deployments, they located the jellyfish in under 25 minutes, scared the other scavengers away almost immediately and consumed over 50% of the carcass. We looked at the nutritional value of the jellyfish, along with average Norway lobster energy intakes in the Firth of Clyde, and found that just one of these jellyfish could satisfy the lobster’s energy requirements for up to three months.

“Jellyfish have historically been considered a ‘dead end’ in the marine food chain and it was only in 2012 that we discovered that anything was using it as a food source.

“To discover that it’s a potentially huge food source for one of the Atlantic and North Sea’s most commercially important catches is really interesting and raises questions about how jellyfish could contribute to sustainable commercial fishing.”

Dr Sweetman added: “There are various species of jellyfish in Scottish waters and lochs and I’m confident any 
Norway lobsters in those areas will also be feasting on the carrion.

“An interesting next step would be to find out how the Norway lobster are using the energy from the jellyfish.

“New techniques mean we could label jellyfish tissue with an isotope and trace it in the lobster, so we could actually tell whether it was going intoreproductive cells or helping general growth.”