The addition of histidine in the diet of salmon helps prevent cataracts in fish. (Photo: University of East Anglia)
Scientists solve farmed salmon industry's cataract problem
Monday, October 04, 2010, 11:00 (GMT + 9)
Eye specialists at the University of East Anglia (UEA) have determined how the nutrient histidine prevents cataracts. The nutrient stops cataracts from forming when added to the diet of farmed salmon, says research published in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology.
The nutrient is present in high quantities in blood meal, which was eliminated from the diet of farmed salmon due to concerns regarding mad cow disease (BSE) in the 1990s, and this led to drastically increasing numbers of fish getting cataracts. Economic losses and fish welfare problems ensued.
"We also found that by adding histidine to the salmon's diet, cataract could be prevented. During the life cycle of salmon the young salmon parr spend the early part of their life in fresh water before they enter the sea as salmon smolts where they grow to maturity before returning to fresh water to spawn,” told lead author Dr Jeremy Rhodes from the Norwich Eye Research group at UEA.
"In this paper, the latest of several from the project, we show that histidine has a protective role in the lenses of salmon enabling them to withstand the considerable environmental stresses that their life cycle demands. When histidine is deficient in the diet, these environmental stresses lead to the development of cataract," he explained.
Norway is the chief producer of farmed salmon, leading a USD 11 billion worldwide industry. It produces a 33 per cent share.
Aquaculture comprises Norway's third largest export after oil and metals.
The Norwich Eye Research Group has played a critical role. It has also hosted scientists from the NIFES labs in Norway and sent scientists there to help gather samples and create new techniques.
The dietary histidine has been increased in the diet of farmed salmon as a direct result of this collaborative research, thus having an impact on the international salmon farming sector.
A synthetic histidine compound was recently approved by the European Food Safety Authority
(EFSA) for use within the European Union (EU) due to the findings of the research.