Ireland's sailing, boating & maritime magazine

In association with ISA Logo Irish Sailing How Jellyfish Can Sting Coastal Economies

6th January 2010 How Jellyfish Can Sting Coastal Economies

The serious impact of jellyfish swarms on coastal economies was described by Dr Tom Doyle of the Coastal & Marine Resources Centre at University College at a recent Beaufort Marine Socio-Economic Workshop at the Marine Institute.

Once considered unimportant as a factor in coastal economies, jellyfish are now playing increasingly significant roles in coastal ecosystems and processes. This has happened due to regular occurrence of jellyfish blooms around the coast of Ireland with negative consequences for tourism, fishing,  and fish farming. 

“In 2005 people were simply afraid to get into the water around Dublin because of blooms of the dangerous ‘Lion’s Mane’ jellyfish,” said Dr Doyle. “And the emergence of ‘open water swimming’ as part of triathlons means that more and more swimmers can potentially come into contact with these animals.”  

But jellyfish are not only a threat to swimmers. Large swarms of jellyfish were responsible for the destruction of an entire fish farm’s stock of salmon, worth £1 million, in Glenarm, Northern Ireland in 2007. 

Fishermen too are noticing the problem as their nets become clogged with masses and masses of jellyfish on an increasingly regular basis. “Not only do the jellyfish clog the nets and make them less efficient, but the increased cost of labour in removing them, not to mention the danger of capsize as smaller boats attempt to pull in their bulging nets, or the painful stings encountered in removing them, are making jellyfish a serious threat to fishing during times when they occur,” said Dr Doyle. “I know of one example when the sheer weight of jellyfish in a pair-trawl off Dublin was large enough to physically stop the boats pulling it in their tracks.”  

Dr. Doyle suggests that increasing seawater temperatures related to climate change, increased eutrophication in coastal waters and overfishing may have contributed to their increase in recent years. “As we continue to remove enormous amounts of fish from the sea, we can open up ‘ecological space’ for jellyfish to fill, as the removal of such fish provides more food (zooplankton) for jellyfish” he said.  

Dr Doyle is currently involved in an EU project ECOJEL project, to track the migration of jellyfish in European waters and better understand their movements and overall ecology as well as the Marine Institute NDP-funded project GILPAT that is examining the effect of jellyfish on farmed salmon. 

Further information on these projects is available at .  

The workshop, which was held at the Marine Institute headquarters at Oranmore, Co. Galway was organised by NUI Galway to discuss the results to date from work carried out by its newly formed Socio-Economic Marine Research Unit (SEMU) and research being carried out nationally in the area of marine socio-economic research.

Published in Coastal Notes Team

About The Author Team

Email The Author is Ireland's dedicated marine journalism team.

Have you got a story for our reporters? Email us here.

We've got a favour to ask

More people are reading than ever thanks to the power of the internet but we're in stormy seas because advertising revenues across the media are falling fast. Unlike many news sites, we haven’t put up a paywall because we want to keep our marine journalism open. is Ireland's only full–time marine journalism team and it takes time, money and hard work to produce our content.

So you can see why we need to ask for your help.

If everyone chipped in, we can enhance our coverage and our future would be more secure. You can help us through a small donation. Thank you.

Direct Donation to Afloat button

Coastal Notes Coastal Notes covers a broad spectrum of stories, events and developments in which some can be quirky and local in nature, while other stories are of national importance and are on-going, but whatever they are about, they need to be told.

Stories can be diverse and they can be influential, albeit some are more subtle than others in nature, while other events can be immediately felt. No more so felt, is firstly to those living along the coastal rim and rural isolated communities. Here the impact poses is increased to those directly linked with the sea, where daily lives are made from earning an income ashore and within coastal waters.

The topics in Coastal Notes can also be about the rare finding of sea-life creatures, a historic shipwreck lost to the passage of time and which has yet many a secret to tell. A trawler's net caught hauling more than fish but cannon balls dating to the Napoleonic era.

Also focusing the attention of Coastal Notes, are the maritime museums which are of national importance to maintaining access and knowledge of historical exhibits for future generations.

Equally to keep an eye on the present day, with activities of existing and planned projects in the pipeline from the wind and wave renewables sector and those of the energy exploration industry.

In addition Coastal Notes has many more angles to cover, be it the weekend boat leisure user taking a sedate cruise off a long straight beach on the coast beach and making a friend with a feathered companion along the way.

In complete contrast is to those who harvest the sea, using small boats based in harbours where infrastructure and safety poses an issue, before they set off to ply their trade at the foot of our highest sea cliffs along the rugged wild western seaboard.

It's all there, as Coastal Notes tells the stories that are arguably as varied to the environment from which they came from and indeed which shape people's interaction with the surrounding environment that is the natural world and our relationship with the sea.

Who is Your Sailor Sailor of the Year 2019?
Total Votes:
First Vote:
Last Vote:

Featured Sailing School

INSS sidebutton

Featured Clubs

dbsc mainbutton
Howth Yacht Club
Kinsale Yacht Club
National Yacht Club
Royal Cork Yacht Club
Royal Irish Yacht club
Royal Saint George Yacht Club

Featured Brokers

leinster sidebutton

Featured Webcams

Featured Associations

ISA sidebutton
isora sidebutton

Featured Events 2020

Featured Chandleries

CHMarine Afloat logo
osm sidebutton
viking sidebutton

Featured Sailmakers

northsails sidebutton
uksails sidebutton

Featured Marinas

dlmarina sidebutton

Featured Blogs

W M Nixon - Sailing on Saturday
podcast sidebutton
mansfield sidebutton
BSB sidebutton
sellingboat sidebutton

Please show your support for Afloat by donating