Effects of handlings on phosphorus deficient fish on the occurence of vertebral deformities in juvenile Atlantic salmon

Previous trials at Skretting ARC have demonstrated that the phosphorus deficient vertebral phenotype of Atlantic salmon are under mineralised but without any skeletal malformation. In addition, we have shown that phosphorus deficient salmon skeleton can be re-mineralized without tissue alterations. This phenomenon gives us the opportunity to test in a systematic manner individual factors that affect the growth of under-mineralised bone. Thus we would like to test the influence of diet and common farm handlings on the risk of the occurrence of deformities in 1200 farmed salmon (S.salar). These handling procedures are common farming practices. This will enable us to test the effects of handlings happen to fish during farming conditions on the occurence of vertebral deformities in phosphorus deficient salmon. Additionally, appropriate phosphorus inclusion levels and their potential efffects will be determined. As oversupply of phosphorus in diets results in pollution and eventually leads to anoxic zones. Due to the unknown aetiology of deformities in salmonid aquaculture live animals must be used, however, the number used in the experiment is limited to that which will provide significant differences between control and experimental groups (assuming an alpha value of 0,05 and a power of 0,8).