String jellyfish, known in Norwegian as Perlesnormanet.
Norwegian Institute of Marine Research
Norwegian fish farmers are bracing for another influx of the deadly "pearl chain" or string jellyfish Apolemia, known in Norwegian as perlesnormanet. Last winter, unusually high numbers of this type of jellyfish appeared in Norwegian waters, and led to mortalities of an estimated 3 million fish in net pens.
Sightings of the jellyfish are once again on the rise this year, prompting Mattilsynet, the Norwegian Food Safety Authority, to issue a warning for aquaculture operators to be prepared to take prompt action.
The pearl string jellyfish, a colony species that releases venom harmful to fish, typically appears along the coast in late autumn, with peak sightings in November and December - but despite the huge impact the organisms can have, scientific knowledge on the jellyfish is limited.
To tackle this, researchers led by the Norwegian Institute of Marine Research and the University Museum of Bergen are working on the JellySafe project to build more knowledge about jellyfish biology and movements on ocean currents, as well as to enable earlier detection and response to the jellyfish using artificial intelligence and drone technology.
The JellySafe project’s first focus is on using artificial intelligence to recognize and track the jellyfish, a task led by the University Museum of Bergen. Through a high-tech imaging system called FlowCam, researchers will analyze water samples, creating a visual database that AI can use to detect even the smallest jellyfish fragments.
Meanwhile, the Norwegian Institute of Marine Research is developing a low-cost underwater drone specifically to detect the jellyfish. Equipped with cameras and an AI model trained to recognize the "pearl chain" jellyfish, the drone will navigate coastal waters, scanning for any signs of the dangerous species. Upon detection, the drone will capture close-up images and report back, alerting researchers to potential threats.
A further aspect of the project is analyzing ocean ocean patterns to predict where jellyfish may appear next. Researchers intend to investigate the connection between physical conditions in the sea and the appearance of the deadly jellyfish along the Norwegian coast.
By examining environmental conditions such as wind and water currents, the scientists aim to create a five-day “jellyfish forecast,” enabling fish farms to take preemptive measures.
According to Tina Oldham, a fish welfare specialist and leader of the JellySafe project, while barriers can help keep jellyfish out, they reduce water flow, which in turn can lower oxygen levels critical for fish health. She advises fish farms to monitor oxygen levels, avoid stressful handling, and halt feeding during jellyfish threats.
When jellyfish do enter fish pens, they can break apart, spreading venomous fragments that remain harmful. Oldham’s research explores fish behaviour under jellyfish threat, aiming to build a library of fish reactions. By understanding these behavioural cues, Oldham says, AI-driven cameras in pens could detect signs of jellyfish presence remotely.
The JellySafe project has received nearly 35 million kroner (USD 3.3m / EUR 3.1m) in funding from Norway's Seafood Research Fund (FHF).
Led by the Norwegian Institute of Marine Research, the project incorporates partners SINTEF, Akvaplan-niva, NIVA, UiB, Patogen, NCE Aquaculture, and Åkerblå.
