European scientists have realised that warm water can trigger deformities in farmed fish. These findings are the result of the FINE FISH research project, funded under EU Sixth Framework Programme.

EU-funded researchers have discovered that temperatures greater than 16°C can cause skeletal deformities in young salmon. The finding is part of the FINE FISH ('Reduction of malformations in farmed fish species') project, which received EUR 3.02 million under the SME (small and medium-sized enterprise) cross cutting activity of the Sixth Framework Programme (FP6).

Spinal disorder, which can occur relatively frequently among intensively farmed fish, presents an important health and productivity challenge for the aquaculture sector. Unfortunately, there is a lack of information on the underlying molecular mechanisms involved in bone deformities in fish and other farmed animals which would help curb this problem.

The team of four scientists from Chile and Norway involved in the study wanted to improve on this knowledge base by studying the bone metabolism and pathogenesis of vertebral fusions in Atlantic salmon (Salmo salar).

The researchers reared 400 juvenile salmon in water at a temperature of 10°C and a further 400 at a temperature of 16°C. Salmon farmers often use warmer water to increase fish growth rates, and the two tanks with the two temperatures were observed over a period of time to document any ensuing differences as a result of temperature.

The study showed that bone and cartilage production was disrupted when temperatures were elevated. This resulted in an increased rate of deformities for the 16°C group. This group of fish grew faster, but more than a quarter (28%) was found to show some signs of skeletal deformity (compared to 8% of the fish in the 10°C group).

The researchers conducted further studies specifically on the salmon with the vertebral abnormalities and found that the deformity process involves molecular regulation and cellular changes similar to those found in intervertebral disc degeneration in mammals.

The findings add to a considerable body of work produced under the FINE FISH project. FINE FISH generated new practical knowledge on how to reduce the incidence of malformations in the major fish species used in European aquaculture production, and how to apply this to the professional sector, made up largely of SMEs. Eleven of the 20 partners that committed time under FINE FISH were SMEs.

As a result, there are several tools available on the project's website including the FINE FISH diagnostic manuals for individual species (bass and bream, industrial monitoring, cod, trout, and salmon) and material used in the series of training courses.

The Federation of European Aquaculture Producers (FEAP) estimates that 650,000 tonnes of fish are farmed in the EU annually. Within Europe as a whole, the total production is more than 1.6 million tonnes. Norway, with over 860,000 tonnes of salmon and trout produced each year, is a major contributor to Europe's aquaculture sector.

Hatcheries produce fertilised eggs, larvae, fry and juveniles that represent the valuable starting materials for the majority of European fish farmers.