Salmon is the new guinea pig

First published in Norwegian on 11 October 2021.

Neither mice nor rabbits are the most frequently used test animals in Norway. Statistics from the Norwegian Food Safety Authority show that it is in fact salmon, by a clear margin. Salmon make up 75 per cent of all test animals in Norway. This figure is also high in a European context. No other country in the EU/EEA reports such prolific use of fish in animal testing as Norway. 
 
‘Norway is unique in its extensive use of fish as test animals’, says Tore Kristiansen, head of research at the Institute of Marine Research (IMR). He also chairs the National committee for the protection of animals used for scientific purposes, an independent committee that was founded in 2019 and advises authorities and research communities involved in animal experimentation. 
 
Kristiansen has extensive experience with research in the field and heads up IMR’s animal welfare group. He himself conducted research on fish for a number of years. Based on his own experiences, Kristiansen believes that the number of salmon and other fish used for research could have been reduced. 
 
‘It’s likely that a critical review would have shown that we could have reduced the number’, he says. 
 
The IMR researcher nevertheless believes that developments have moved in a positive direction in terms of the thinking around fish as test animals. This is part of a larger trend in society. 
 
‘In our culture, we have cared little about the plight of the fish, and we’ve treated them as if they are vegetables. But there has been a major shift in attitudes in recent decades’, he says. 

Fish farming drives research 

The high figure must be viewed in the context of the strong growth and need for development in a number of areas in Norwegian fish farming, from new vaccines to combat disease, to testing feed and treating  salmon lice. 
 
The high mortality rate in Norwegian fish farming is also a factor. At any given time, approximately 400 million salmon are found in net cages along the coast. Last year, it was reported that 52 million salmon died in these cages, according to figures from the Norwegian Veterinary Institute. This is partly due to disease and the negative effects from the harsh treatment of salmon to remove salmon lice. 
 
The hope is that research into fish health will help improve fish welfare and reduce the mortality rate, thereby benefiting a large number of fish. Meanwhile, the extensive use of fish as test animals poses an ethical challenge. 
 
Research suggests that fish feel pain and react to stress and unwanted environmental stimuli. Animal experimentation legislation places fish on an equal footing with other animals, and states that no animal should be subjected to unnecessary stress. 

The new guinea pigs 

Salmon is the largest species among test animals, but research is also conducted on a number of other fish species. In 2020, a total of 2.2 million fish were used in animal experiments in Norway, compared to 56,000 mice and other mammals, 12,000 birds, and a small number of frogs and reptiles. 
 
Efforts to reduce the use of salmon and other fish in research should be stepped up, believes Ingunn Sommerset, head of fish health at the Norwegian Veterinary Institute. She has previously conducted research in the private sector and used test animals. 
 
‘Fish are slippery and smooth and totally expressionless. I think the human race in general often fails to recognise fish as animals that can feel pain and fear’, she says. 
 
Earlier this year, Sommerset addressed the challenges of using fish in animal experiments at a seminar held by the Norwegian Council for Animal Ethics and Norecopa, an organisation that works for the advancement of knowledge on alternatives to animal experimentation. 
 
Sommerset particularly points to the testing of prequalified vaccines as a difficult topic. The prequalification process for quality approval of such vaccines often involves burdensome infection testing, where each individual production batch must be approved. 

Benefits members of the same species 

The phasing out of animal experimentation is not a realistic goal, according to Sommerset. She also believes that it would not necessarily improve animal welfare overall.

The controlled experiments that are carried out on the salmon will benefit their conspecifics, in terms of improved fish welfare at the fish farms. 
 
‘We need to experiment on a limited number of fish in order to generate the knowledge needed to improve the welfare of a much larger population of fish. In these cases we are not using salmon as a model organism to provide insight into other organisms’, points out Sommerset.

She considers it problematic that much of the animal experimentation is never published. This makes it difficult for researchers and the authorities to assess whether specific experiments are necessary. It is also prevents others from using the results. 
 
‘Researchers should be required to publish all results, both positive and negative, when conducting research that involves animal experimentation’, says Sommerset. 

‘Euthanising fish pains me’ 

Several research institutes are trying to develop alternative methods to using live fish in research. One of those involved in the work is Elisabeth Ytteborg, a researcher with Nofima. 
 
Nofima is a Norwegian research institute that carries out extensive research in fish health. It has offices in several locations in Norway, and Ytteborg is based at the department in Ås. In her research career, she has always been mindful that animal experimentation should be limited. 
 
‘I’ve worked with fish since 2006, and euthanised many. It still pains me to do it. You’d think you would get used to it, but I never have’, says Ytteborg. 
 
She believes that alternative models to using live fish are sorely needed in the study of fish health. The models must be developed from scratch, based on in-depth knowledge of the physiology of the individual species. 
 
Alternative models are much more advanced for species such as mice or zebrafish, often enabling researchers to pick and choose. The picture is quite different for salmon, and even worse for species such as cod and lumpfish, which are also important in Norwegian fish farming. 

Developing alternatives 

Ytteborg and her colleagues have successfully tested new methods based on the use of cell samples from the skin and gills of salmon to investigate the harmful effects of hydrogen peroxide. This substance is used to treat salmon lice. According to the Nofima researcher, the results show that parts of the investigation can be carried out at cellular level. This would limit the number of fish subjected to stress. 
 
‘Many new products and methods that enter the market, and which can potentially impact on the health of fish, should and can be tested in models as cell cultures first’, says Ytteborg. 
 
Together with Carlo C. Lazado, a colleague at Nofima, she received an award earlier this year for her research in the field. The award was handed out by Norecopa, an organisation that works for the advancement of knowledge in alternative methods of animal experimentation. 
 
Ytteborg and her colleagues are now working on developing new cell models for lumpfish, a so-called cleaner fish whose task is to eat lice from farmed salmon. In 2020, 161,000 lumpfish were used in experiments. 
 
‘We can’t stop animal experimentation completely, but we can reduce the number of fish used’, says Ytteborg. 
 
She believes that progress is being made. In addition to reducing stress and suffering, alternative methods can often save time and resources. 

Big cages enable big experiments 

The Norwegian Food Safety Authority (NFSA) is responsible for approving applications for animal experimentation. The NFSA categorises the experiments according to the degree of stress that the test animals are subjected to. The main categories are mild, moderate and significant stress. 
 
Gunvor Kristin Knudsen, a senior advisor at the NFSA, notes that under the Norwegian regulations, new methods and equipment for treating animals must be tested and considered suitable from an animal welfare perspective. 
 
‘This also applies to fish, and often requires animal experimentation. The innovative nature of Norway’s large fish farming industry means that its experimentation activity is extensive’, says Knudsen. 
 
Some experimentation is done in commercial facilities, where one net cage can hold up to 200,000 fish. 
 
Knudsen says that various quarters have suggested that Norway may need more test facilities to try out new methods for fish farming on a smaller scale. Increased use of smaller facilities could help reduce the number of test animals per experiment. 

360,000 salmon in one experiment 

Figures from last year show that some experiments with salmon involve huge numbers of fish. The largest of these comprised a staggering 360,000 salmon. The five largest single experiments all used more than 100,000 salmon. All of these were in the ‘mild stress’ category, which can involve, for example, taking the fish out of the water, sedating and tagging them, and returning them without further discomfort.

Furthermore, over 60,000 salmon and other fish (excluding zebrafish) were used in animal experiments where the stress on the fish was categorised as severe. Individually, these experiments are smaller in terms of number of fish. Last year, the largest of the individual experiments in the ‘severe’ category included 7,800 fish. 
 
Tore Kristiansen of the committee for test animals believes that it is the scope of the experiments with a large stress factor that needs to be reduced most urgently. 
 
‘What are you calling on researchers to do?’ 
 
‘First of all, to be critical to what they subject the fish to, and to carefully consider whether their experiment is properly designed, and if it is absolutely necessary. They should be more quality conscious and keep in mind that they are dealing with animals. They are living creatures’, he says. 
 
Translated from Norwegian by Carole Hognestad, Akasie språktjenester AS.