As the school holidays approach, the Marine Conservation Society (MCS) is calling on British seaside visitors and sea users to take part in the national Jellyfish Survey and report their sightings of these bizarre but fascinating creatures. Large “blooms” or swarms of jellyfish have already been reported to MCS despite the unseasonal weather, and as the UK’s seas warm up, more jellyfish blooms are expected throughout the summer.

“Britain’s jellyfish seemed to get off to a slow start this year, but then really picked up in May and June when we started to receive reports of large blooms, despite the lack of summer sunshine,” said Peter Richardson, MCS Species Policy Officer, “Blooms of the beautiful and largely harmless moon, blue and compass jellyfish have been reported stranded on beaches in southern England, Wales and the west coast of Scotland.”

The MCS Jellyfish Survey aims to uncover the little-known habits of British jellyfish, as part of a research programme to help protect the critically endangered leatherback turtles that migrate thousands of miles to UK waters to feed on their favourite jellyfish prey each summer. By mapping where and when the jellyfish are seen, MCS hopes to understand more about leatherback turtles while they visit in UK seas.

Over 4,000 jellyfish encounters have been reported since the MCS Survey was launched in 2003. The survey data will be fully analysed later this year in collaboration with the University of Exeter’s Centre for Ecology & Conservation, but initial analysis of these public reports is already showing interesting differences in the distribution of the six larger jellyfish species around Britain.

Barrel
(harmless)
Largely restricted to the Irish Sea, Solway Firth, Firth of Clyde
Large blooms off northwest Wales in March, with some reports through to June.

Lion’s Mane
(powerful sting)
Northern seas, not usually recorded south of the Irish Sea or Northumberland.
Some reported in May, started to bloom off west Wales in June.

Blue
(mild sting)
Entire UK coast.
Started to bloom around the UK coast in May, continued through June.

Compass
(mild sting)
Entire UK coast, but with most records from SW England and the Irish Sea
Unusually early blooms in South west England through June

Moon
(harmless)
Entire UK coast.
Started to bloom in England and Wales in May, with mass blooms off east and west Scotland through June.

Mauve stinger
(powerful sting)
Occasionally reported from the Channel Islands and SW England
No UK records so far, although large blooms reported in parts of the Mediterranean.