The case in summary Unusually high sea temperatures have led to an explosion of salmon lice in northern Norway, which has created major challenges for the farming industry. The farming industry in Northern Norway was not sufficiently prepared for this situation, and now has to slaughter large quantities of fish to deal with the problem. The Institute of Marine Research (HI) already warned in 2021 that higher temperatures will lead to more salmon lice in Norwegian fjords. It is necessary for the farming industry to prepare for an increased incidence of salmon lice and higher temperatures in the future. It is being discussed whether it is necessary to reduce the amount of fish in the cages, start lice removal earlier and develop new technology to deal with the problem. The summary is made by an AI service from OpenAI. The content is quality assured by news’s journalists before publication. – What we see here is that there are lice everywhere, so this is a rather extreme situation, says Anne Dagny Sandvik. She is a researcher at the Institute of Marine Research (HI). On the screen, she has a video of a fish with large amounts of salmon lice attached to its body. – At the end of July, we saw that the lice numbers rose and rose in northern Norway. It became an epidemic, with extremely high lice numbers. Far above what we have seen previously, she says. Salmon lice from farms can be transmitted to wild fish. The Institute of Marine Research has registered a lot of salmon lice on trout in connection with the bloom this summer. Photo: Oddgeir Øystese / news Already a month ago, climate scientists sounded the alarm: Increased temperatures in the sea present challenges to the farming industry. Warmer water can both damage the fish directly and affect the disease picture in the cages. In addition, warmer water causes a flourishing of salmon lice, which has hit Northern Norway hard. The figures for HI are clear. Temperatures in the sea were in several places in the north around 4–5 degrees above normal. Then the cases of salmon lice skyrocketed: the company Nova Sea is among those affected. – We are affected by the high sea temperatures. This has meant extra lice treatments, says production director, Bjørn Helge Hjartåker. – At the same time, the temperature makes it more difficult to do that job with regard to fish welfare. Nova Sea uses several methods for lice removal: – Rinsing and tempered seawater that is used where it gives the best effect against lice and is as gentle as possible for the salmon, says production director, Bjørn Helge Hjartåker. Photo: Synnøve Sundby Fallmyr Farming taken to bed – When the water gets warmer, lice multiply faster. In addition, it becomes more contagious. 15–16 degrees are optimal conditions for salmon lice, says Anne Dagrun Sandvik. The farming industry in Western Norway and parts of Trøndelag often experience these types of temperatures and blooms of salmon lice. – But they were not prepared for such a drastic change in northern Norway this year, says Sandvik. Geir Ove Ystmark in Sjømat Norge calls the situation in northern Norway extreme. He acknowledges that the breeding companies were not sufficiently prepared. Salmon lice are a natural parasite on saltwater salmon in the northern hemisphere. It feeds on the mucus, skin and blood of the fish. Photo: news Salmon louse Salmon louse (Lepeophtheirus salmonis) is a natural parasite on salmonids in saltwater in the northern hemisphere. It feeds on the mucus, skin and blood of the fish. This makes the fish more susceptible to other infections. Salmon lice in farms have led to an increased incidence of salmon lice on wild salmon. Limits have therefore been introduced for how many salmon lice salmon can have in farms. During the period when wild salmon migrate from the rivers to the sea, the limit value is set at 0.2 adult female lice per fish. For the rest of the year, the limit value is set at 0.5 adult female lice. More than 10 salmon lice on a salmon smolt can be fatal. Males are 6 mm long, while females are 12 mm. Salmon in farms have been treated with various drugs in feed or bath, but over the years the lice have become resistant to several of the agents. Non-medicinal methods such as cleaning fish, flushing and laser have also been used. Source: Veterinærinstituttet and Havforskningsinstituttet – In Trøndelag and in Western Norway, they have increased capacity, among other things when it comes to boats that are used to treat salmon lice and to transport the salmon to slaughter. In Northern Norway, that capacity is too small, says Ystmark. – What consequences does this have for the industry? – It varies between companies, but in general the level of lice is higher than normal. It is serious for the industry. They must deal with lice with treatment and by slaughtering salmon to reduce the number of fish in the area. Sjømat Norge has no concrete figures for the large quantities of fish that must be slaughtered. With autumn, temperatures in the sea will drop and the situation will stabilise. But Anne Dagrun Sandvik at HI still believes that the industry must take the incident seriously. – It is not a crisis for the industry, but we must brace ourselves for an increased incidence of salmon lice and higher temperatures, says Geir Ove Ystmark in Sjømat Norge. Photo: Jonas Kroken Sævereide / news Has warned against this for several years Already in 2021, HI warned that higher temperatures will lead to more salmon lice in Norwegian fjords. And international climate scientists believe that so-called marine heat waves will occur more often and be fiercer in the future. – For example, we will have to rethink how much fish can be released into the sea, start de-lice removal earlier and ensure that we are prepared as necessary for it to happen again, says Anne Dagrun Sandvik. She still has faith that breeders in Northern Norway will be able to adapt to developments. – I know that they in the north are very good, for example when it comes to adopting and developing new technology. Geir Ove Ystmark does not think a permanent downward adjustment of the number of fish in the cages is the way to go. Anne Dagrun Sandvik at the Institute of Marine Research believes it is time to discuss the amount of fish in the cages. Photo: Andrea Ånestad Don’t want fewer fish in the cages – We have a separate system which means that lice and lice management affect growth in the various areas, says Ystmark. He refers to the so-called traffic light system. The system determines how far the breeders have to reduce their production, or whether they can produce more fish, based on how much salmon lice affect wild salmon in the area. – In addition, we use a lot of new technology in aquaculture which will help to solve the challenge of lice. For example, submersible, partially closed and closed facilities, he says. – We believe good localization and good capacity to reduce production if there are a lot of salmon lice is the way to deal with it. Despite the fact that scientists have warned against both higher temperatures and more salmon lice for several years, Ystmark denies that the industry has been sleeping on the clock. – The extreme temperatures this year have surprised many. It came upon us sooner than we had anticipated. Now we must make sure to build up the capacity for both treatment and slaughter. Published 19.09.2024, at 16.19
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High temperatures in the sea have led to an explosion of salmon lice in northern Norway – news Nordland
