Increased water current induces micro-architectural changes to the vertebral bone of juvenile rainbow trout (Oncorhynchus mykiss)

In terrestrial animals the link between exercise and bone physiology is well described, however this is not the case for fish. Abnormal bone physiology is a growing problem for intensive aquaculture, we therefore examined if water current affected bone quantity and quality in juvenile rainbow trout. Random groups of trout were assigned to one of two treatments, high current (two body lengths per second) or low current (zero body lengths per second), and fed a commercial diet for ten weeks. At the end of the trial no significant differences were elucidated for growth or body conformation. However the histomorphometry of the vertebrae from the trunco-caudal area of the spinal column was assessed and total bone area and trabecular thickness were found to be reduced (p = 0.04, p = 0.01), while the whole bone mineral content, and autocentrum width were observed to increase (p = 0.01). These changes however did not result in any significant differences in the mechanical properties of the vertebrae. This data suggests that exercise induces morphological changes to vertebrae which, over a longer production period than utilised in the present study, may influence the mechanical properties of the bone.

► Trout trained using a water current (2 BL s− 1) compared to untrained trout (0 BL s− 1). ► Histomorphology and mechanical properties of trunco-caudal vertebrae assessed. ► Training increased vertebral mineralisation and autocentrum width. ► Training reduced trabecular thickness and bone area. ► Vertebral mechanical properties were not affected by training.