Sting operation

Two projects are looking to unravel the secrets of the string jellyfish, as Vince McDonagh reports.

As children visiting the seaside we all remember being told to stay out of the water when jellyfish are around.

But for fish farmers in the northern hemisphere this year these strange creatures have become much more than a nasty sting. They have developed into a serious menace, killing millions of young salmon in Norway and Scotland last winter.

The cost to the industry has been huge whether measured in kroner or sterling. Dozens of companies were hit in Norway in particular, with big names like SalMar, Mowi and Leroy badly affected.

Now two key projects are underway to try to prevent a repeat of last winter’s near-devastating attacks.

Institute scientist Angelico Madaro takes samples of farmed salmon after a jellyfish operation in the facility at the research station in Austevoll

More immediately, the Norwegian Institute of Marine Research (IMR) has embarked on the more urgent mission because it is Norwegian companies that suffered the most.

The Faroe Islands have now also entered the fight with the Faroese Aquaculture Research Centre launching GLOBECC, a newly funded project that will lay the foundation for monitoring jellyfish biodiversity in Faroese waters. The salmon farmer Bakkafrost is helping out.

The threat to salmon farmers doesn’t come from those familiar see-through blobs in seaside rock pools (moon jellyfish), but from a species known in Norway with the regal sounding name of perlesnormanet.

They look like long pieces of white ragged string or cotton – hence they are also known as “string jellyfish” – and can stretch to several metres in length.

What the industry doesn’t know yet is whether last winter’s attacks – and it is in winter that they arrive – was a “once in 10 years” event or is likely to become a regular menace.

The Institute has just been awarded NOK 35 million (£2.5m) from the Norwegian Fisheries and Aquaculture Industry’s research funding (FHF) to launch a project called JellySafe to try to avoid a repeat this year.

Tina Oldham

Marine Researcher Tina Oldham said: “The whole point of research is to investigate things we don’t know, but the perlesnormanet situation is unique. It is unusual how little we know about something that has had such a big impact.”

She added: “When last year’s autumn months slipped into winter, large quantities of perlesnormanet drifted towards the Norwegian coast. The consequences of the unwanted guest were enormous.”

And, after Norway, they came for Scotland.

Understanding the unknown
The perlesnormanet is a colony jellyfish, which is made up of several smaller individuals. Some of the individuals have nettle cells, and these kill fish that come too close.

Oldham explained: “In the face of waves, turbulence and physical barriers, the jellyfish colonies are broken up – and these small pieces can penetrate breeding cages.

“This happened again and again and again at farms along the coast. The smokers were powerless.

“We lack both the knowledge and the infrastructure that prepares us to meet such harmful plankton.”

Oldham is leading a completely new research project that should help to equip the industry to deal with the type of dangers that come drifting with the ocean currents.

Quite a lot was already known about this type of jellyfish. But when they started to cause trouble last winter, marine scientists scrambled to acquire more knowledge – both about the fish that were harmed and the jellyfish that caused it.

They secured samples from the jellyfish initiative at its research station in Austevoll, Norway, and started a project to find mitigating measures when the jellyfish were close to a coma condition.

JellySafe plans to build on this earlier work with the knowledge Oldham and her team have already acquired. She said the project involves a wide range of people: “…everything from engineers, mathematicians and oceanographers to fish health researchers, zooplankton ecologists and molecular biologists.”

“We are not giving up on a single question. We will examine the whole picture,” she adds.

This ranges from the biology of the jellyfish and how it is affected by biological driving forces, to how we can use all this knowledge to develop strategies and measures to meet the danger – and ensure that the information reaches those who need it.

Firum, former Fiskaaling, Faroes

It is not just commercial fish farms that are affected. The Institute itself had to euthanise its own fish for animal welfare reasons following a jellyfish attack at its sea facility in Austevoll.

The Faroese investigation is a longer term venture. Led by Dr Amanda Vang, Head of the Biotechnology Department at the research centre, GLOBECC will draw on a multi-disciplinary team of Faroese and Norwegian research partners, as well as industry collaboration.

The two-year project will leverage existing marine research surveys from The Aquaculture Research Centre and the Faroe Islands Marine Institute, aquaculture monitoring initiatives with Bakkafrost, and citizen science projects with the Arctic Oceanarium of the Faroe Islands.

A main goal of the project is to establish the first reference database for Faroese jellyfish. This database will consist of microscope images and DNA analysis of jellyfish collected during the project.

The database will then be used to design genetic tests for identification of high-risk species as a tool for Faroese aquaculture management.

Perles normanets

A collective threat
The perlesnormanet can be up to 30 metres long, but the colony can sometimes be broken up into smaller pieces by both waves, turbulence and physical barriers – such as cages – so before they reach the coastline they can be in many small parts.

It was one night during a jellyfish attack last November that the Institute team saw the salmon had been badly injured.

“It is these small pieces that are problematic. If an individual with nettle cells enters a cage and hits a fish, he can get wounds and damage to the gills and burns to the skin,” said IMR Researcher Lars Helge Stien.

Perles normanets (string jellyfish)

It was a difficult incident, but at least it has helped the team gain more knowledge about the problem.

Stien said: “We are aware of two previous episodes in which this jellyfish has led to increased mortality in breeding facilities.”

The Institute believes there is a lot more to learn about the jellyfish problem and its consequences for farmed fish.

Hopefully, Tina Oldham and her team can close that gap in time should there be another onslaught this winter.