The vertebral column and exercise in Atlantic salmon — Regional effects

This study investigated the effect of swimming speed on the mineralization (mineral rate, Ca, P, Mg, Zn, K, Mn, Cu) and morphology of vertebra (V) in different anatomical regions of the vertebral column in Atlantic salmon. Triplicate groups of Atlantic salmon post-smolt were forced to swim at slow (0.2±SEM 0.02BLs−1), moderate (0.8±SEM 0.01BLs−1) and fast (1.5±SEM 0.02BLs−1) water current velocities for six weeks in raceways. The specific growth rate (SGR) was lower at fast (1.41±0.04 SEM) compared to moderate (1.49±0.02 SEM) and slow velocities (1.51±0.03 SEM). In the post-cranial region (V1→8) fish at: (i) moderate and fast velocities developed higher relative V lengths, and mineral rate (% ash weight of dry weight), compared to fish at slow velocity; (ii) moderate velocity developed higher ratio between V length and dorso-ventral diameter (l/d-ratio) – more elongated V – and lower potassium ash content, compared to fish at slow, while those at fast velocity displayed intermediate values for both parameters. In the posterior-truncal region (V9→30), fish at moderate and fast velocity developed lower potassium ash content than those at slow. In the anterior-caudal region (V31→49), fish at: (i) fast velocity developed higher mineral rate than those at slow, with those at moderate displaying intermediate values; (ii) moderate velocity developed lower phosphorus and magnesium ash contents than those at slow and fast. In the ural region (V50→58), fish at: (i) slow velocity developed higher relative V lengths than those at moderate and fast; (ii) slow velocity developed higher l/d-ratio than those at fast, with fish at moderate displaying intermediate values. Also, ontological shifts in mineral rate, and Ca and K ash contents along the spine were observed; with time, Ca increased in all regions except the ural, while K decreased in all regions except the ural, where it increased, accompanied with a decrease in mineral rate.The present results show that the positive effects of exercise on vertebrae in farmed Atlantic salmon are region specific.Exercise promotes vertebra mineralization in Atlantic salmon.