September 3, 2010

EU research shows warm water may cause deformities in farmed fish

EU-funded scientists 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 EUR3.02 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.

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 eight% 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.