Does Scotland have the answer to Norway's jellyfish crisis?
A pen liner designed to combat sea lice is being tested as a possible barrier for Apolemia
A small Scotland-based company that has developed semi-permeable pen liners to protect salmon from sea lice is participating in a Norwegian project tackling jellyfish that caused the deaths of 3 million farmed fish last winter.
Salar Pursuits Limited has been invited to take part in the NOK 35 million JellySafe project led by Norway’s Institute of Marine Research (IMR) and involving several institutions and companies including SINTEF Ocean, part of technology research organisation SINTEF.
JellySafe seeks to find out more about the Apolemia jellyfish and develop ways to prevent its stinging cells being washed into salmon pens and harming fish.
Much to discover
There is still a lot to learn. Researchers know that the jellyfish is a colony jellyfish in the genus Apolemia, but not what species.
“The one thing we actually know is that these jellyfish that reach the Norwegian coast are missing their pumping bells - the main individuals that keep the jellyfish moving forward,” said Tone Falkenhaug, a researcher at IMR.
“This indicates that the jellyfish are dying before they reach our coast.”
Apolemia, known by various names including the string jellyfish and the barbed wire jellyfish, is a colonial jellyfish comprised of organisms with different jobs. A colony can be up to 30 metres long but can break up when pushed against a salmon pen net by the current, leading to the stinging cells being pushed through the net into the pen.
Damaging and deadly
The effects of Apolemia stings on the fish varied from reduced appetite and changes in behaviour to death. Fish stung by the jellyfish suffer burns to the skin and eye damage can also occur, which can destroy vision.
Salmon that get stung in their gills can suffocate, and wounds caused by jellyfish also act as a vector for infection, making the fish more vulnerable to disease and death.
Marius Andersen is a researcher at SINTEF Ocean and leader of JellySafe’s prevention work package which looks at physical measures to prevent Apolemia from entering fish cages.
He said researchers had been contacted by several companies, including Salar Pursuits, to suggest that their products can help solve the jellyfish problem.
Acting quickly
“We’re trying to test a semi-permeable net this month if we can get all the logistics lined up. The Apolemia attack is expected to be over by December or January. So, we’re in a bit of a hurry if we’re to do this this year or this season. If not, we’ll do lab-scale stuff and then large-scale testing next [jellyfish] season,” said Andersen.
“We want to look at how a semi-permeable net behaves in the water here and check if there’s a difference in Apolemia concentration inside and outside. We'll be doing that by remotely operated vehicle and photography.”
JellySafe researchers will also lab test different mesh sizes of Salar Pursuit’s semi-permeable material.
“And we’re trying to do some pressure testing to see, using live Apolymia fragments, and basically see which mesh size still passes at pressure," said Andersen.
How small does it go?
“We’re still not sure if Apolemia can release individual stinging cells; whether it splits down to single-cell size or if there's a minimum fragment size.
“We also want to know the mechanical strength of the jellyfish strings. We know they tear apart, but not at what pressures.
“We haven’t planned any mechanical testing on Apolemia yet, but we’ll try to answer these questions by pressure testing the Apolemia fragments through mesh sizes, and maybe we’ll get enough from that.”
Andersen stressed that SINTEF Ocean was at the “green stage” of examining a wide variety of proposed measures, including an air barrier, standard lice skirts, the Harbor Fence electric fence for pens, and even using a sand-like material to sink the jellyfish.
“We’ll do small scale tests first to isolate what measures are feasible and we think might work, and then we'll move them to large scale when we have time.”
Bloomshield
In a LinkedIn post, Salar Pursuits said researchers would be measuring the performance of its fine nylon woven mesh constructions, Smoltscreen and Bloomshield, against the stinging cells of the Apolemia.
“Our Bloomshield system (also designed to provide protection against sea lice larvae, micro jellyfish and toxic algae) can be deployed on an emergency basis, in the event of expected jellyfish invasion, or in a permanent deployment to give full-time protection,” wrote the company.
