Research area

Deformities

In a sustainable biological production, we expect the fish that are produced will be healthy and normal. In aquaculture, at times far too many deformed fish are produced, which is both a welfare problem and a source of financial losses.

The task of charting and eliminating the reasons for deformation in farmed fish is now fully underway.

A decade of research has shown that deformations are preventable, butt his requires a high level of biological knowledge and an awareness of the development of new production routines. To date, some external factors have been charted which can lead to the development of deformation, particularly at an early stage in the lifecycle. All experience shows that normal fish are most productive and in this field there is a clear connection between technical progress, better fish welfare and increased profitability.

Normal to be abnormal?
A certain element of deformation is found in all populations, also among fish, but this element should be low and varied. Deformations in farmed fish have long been observed, but it was not until the mid 1990s that the problem grew to the extent that it made it onto the agenda. When a significant number of fish at most fish farms were observed with skeletal and congenital heart anomalies, there was reason to suspect that systematic failure in the production method had taken place.

Early stage of life
The research has so far shown that temperature at early stages of life is an important reason for deformations among all the species studied. The optimal temperature for normal development may be lower than that which provides the maximum rate of growth. Work to chart the optimal temperature for the different species and life stages is continuing at both Nofima and some of our collaborative partners.

Research also shows that correct mineralisation of the skeleton is a critical factor for normal bone formation, especially in salmonids, with access to phosphorous and zinc in particular restricting factors. Inadequate mineralisation is more decisive when the fish is young, but problems can also arise when the fish is older.

The effects of other external factors are not so clear, but it appears they form part of more complex causal relations.

Industry contact
With research like this, it is decisive to know about the practical realities of production. Consequently, scientists at Nofima studying deformities in fish place considerable emphasis on maintaining contact with the industry to pick up new problems at an early stage. Many changes with procedures, equipment and production strategies also occur rapidly and limiting the distance between the industry and academic community is important if science shall provide relevant knowledge for the industry.

Deformations are preventable
There is major interest in the industry about research on deformations, and generally only a short time passes before findings are implemented in the production. The experiences with salmon are extremely positive. After only a few years, the occurrence of serious deformations has significantly reduced, and is no longer regarded as a major problem for salmon. In the same way, we are now starting to acquire knowledge about the causal relations for other species, in particular cod. However, unsolved issues remain with salmon, and with respect to cod and rainbow trout, there is a long way to go until the problems are under control.

International interest
Nofima Marin has a central role in research on deformations in farmed fish at a national and international level. Through international collaboration, we have learned that many of the problems we see in Norwegian fish species also occur in other farmed species. As part of the EU-financed FINE FISH project, we have used knowledge about causal relations against species to find solutions quicker and more efficiently.

Advanced methods
An advanced x-ray laboratory has been established at Nofima Marin in Sunndalsøra featuring equipment specially adapted for fish. This equipment provides a unique opportunity to study fish during experiments. A significant amount of commercially produced fish are studied here, both as part of monitoring programmes and also on assignment from producers.

Research about mechanisms for the development of deformations enters into the majority of research projects in this field. This work involves the charting of the gene expression in normal and abnormal development and is linked with other information about the fish. This work is included in a long-term plan to understand what goes wrong and why, so that with time we will be better equipped to prevent such problems.

 

A 150g salmon with a good spinal column. Photo: Nofima, Kirsti Hjelde

A 150g salmon with a good spinal column.

An x-ray picture of a halibut with adhesions between the vertebras. Photo: Nofima, Kirsti Hjelde

An x-ray picture of a halibut with adhesions between the vertebras.

A salmon with a shortened and thickened lower jaw. Photo: Nofima, Grete Bæverfjord

A salmon with a shortened and thickened lower jaw.

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