A Marine Conservation Society survey has found that the number of jellyfish spotted in the UK has increased by 32% in the last year.

The most commonly spotted were the barrel, or ‘dustbin-lid’, jellyfish.

Jellyfish populations vary naturally over time but climate change warming the UK seas is creating favourable conditions. In August, oceans hit their highest global average temperature on record.

From October 2022 to September 2023, jellyfish sightings increased by 32% compared with the previous year. Most were on the UK’s west coasts, particularly in Cornwall and Wales. And 11% were of large blooms of more than 100.

The ‘dustbin-lid’ jellyfish can grow to more than 3ft (1m) in diameter. There were 467 sightings of these.  Lion’s mane, Portuguese man o’ war, moon and compass jellyfish were also seen.

The Marine Conservation Society has been asking the public to report sightings of jellyfish for 20 years. “These numbers could be part of a 20-year long boom-and-bust cycle but there are very few surveys out there which show what’s happening,” Dr Peter Richardson said in a BBC report. “But this survey gives us an indication of what’s happening in our seas with climate change.”

Press reports on the MCS report can be read from the BBC, Sky and from the Huffington Post.

The Marine Conservation Society ‘Wildlife Sightings Annual Report’ can be read here.