Last year, 65 million fish died in Norwegian fish farms. That is 7 million more than the previous year, estimates the Institute of Marine Research in the latest risk report for Norwegian fish farming. – Perlesnormaneta can largely take on the responsibility for the increase, says research manager for animal welfare at the Institute of Marine Research, Lars Helge Stien. Perlesnormaneta looks like a long thread, but is actually a colony of several jellyfish. It does not occur naturally in Norway, but can drift with ocean currents to the Norwegian coast. And into the merdane. This “thread” is actually a colony of several jellyfish. They can break up, but the nettle cells are still poisonous. Photo: Rudolf Svensen / Stavanger museum – These threads break up when they hit the net wall in the cages. When they hit the fish, they shoot out a spike that injects nettle poison, Stien says. Some fish die instantly. Others experience fainting or abnormal behaviour, which can cause them to miss the bill and get wounds and injuries. – So we have both an acute mortality rate, but perhaps also a longer-term mortality rate, says Stien. Research manager for animal welfare at the Institute of Marine Research, Lars Helge Stien. Photo: Christine C. Fagerbakke / HI – There is generally mortality from other things such as diseases, deworming and so on, but what explains much of the difference from 2022 to 2023 is this attack with the pearl standard. In addition, the report highlights an increase in the number of farmed fish and outbreaks of pancreatic disease as explanations for the increase. – It is difficult to see how we can avoid it – We obviously want to keep the mortality rate as low as possible, says director of aquaculture at Sjømat Norge, Jon Arne Grøttum. But the industry does not know how to protect the fish from the pearl standard net. Director of aquaculture at Sjømat Norge, Jon Arne Grøttum, says that tarpaulin around the bill and so-called “bubble curtains” are some of the measures on the table. Photo: Seafood Norway – As of today, I have a bit of difficulty seeing what methods or equipment I can use to avoid it, says Grøttum. The research fund for the industry has now set aside funds to look into the problem. Among other things, they have tried stopping feeding to get the fish to go deeper in the cage, and thus go under the jellyfish. – Must be forewarned It is not the first time that pearl Norwegian nets have killed Norwegian farmed fish. Perlesnormaneta was first observed in Norway in 1997, in connection with fish deaths in aquaculture facilities. Photo: Rudolg Svensen / Stavanger museum The first time the species was observed in Norway in 1997, 10–12 tonnes of fish died in breeding facilities on Øygarden and Fedje. An unknown number of tonnes were slaughtered. When the jellyfish returned to the Norwegian coast in 2001, as many as 600 tonnes of farmed fish died. – We can hope that it will be 22 years next time, and maybe even longer, says Grøttum. Through the “Dugnad for the sea” scheme, the public has been able to report observations to the Institute of Marine Research. There they saw a sharp increase in sightings of the pearl gannet as early as autumn 2022. – Will the pearl gannet become more common along the Norwegian coast? – We do not have reliable data on that, but we have received reports from the public in both 2021 and 2022, Stien replies. – So I’m afraid that it will go that way. – 60 million killed by other things Rasmus Hansson (MDG) thinks 3 million fish killed by the pearl norm is bad. But it is the rest of the fish death that he would most like to talk about. – It is important to consider that over 60 million farmed salmon are killed by other things, mostly linked to salmon lice and de-lice. Although the pearl lice are exotic and interesting and kill a lot of fish senselessly, the louse and what it causes is much more important. Now the MDG is presenting a proposal to the Storting which Hansson believes will reduce fish mortality. Among other things, by encouraging the industry to move away from open cages. – Closing millions of salmon in open cages where lice and jellyfish can come from outside and make their lives miserable is a completely hopeless solution in the long term.
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Risk report for 2023 from the Institute of Marine Research – Perlesnormaneta is to blame for the increase in fish deaths – news Vestland
