The effect of different photoperiods on growth and smoltification in Atlantic salmon (Salmo salar)

Photoperiod has been implicated as an effective mediator of growth and smelting in Atlantic salmon (Salmo salar). To investigate this 0+ parr of Atlantic salmon were treated with three different photoperiods: 24Light:0Dark; 16L:8D; 8L:16D; held static during the experimental period. This preliminary report shows that growth was greatest under the continous light regime, followed by the 8L:16D photoperiod and the 8L:l6D regime. Several bloodparametres were measured as indicators of stress. These indicators showed no large differences between photoperiods. Thus, extended periods of light does not seem to stress the fish, on the contrary, manipulating photoperiods is an effective means of increasing growth and controlling smelting in Atlantic salmon