Technical performances (spectral output, light-attenuation and irradiance distance) of the individual light-units were measured and light perception was assessed by quantifying plasma melatonin levels. Body-size parameters (BW, FL, K) were measured at the switch-on and turn-off of the photoperiod regimes. Maturation rates were estimated at the end of the light treatments and at harvest. The B-unit provided the shortest effective irradiance distance (distance from the light-bulb to the minimum irradiance suppressing plasma melatonin to basal day-time level = 0.016 W m−2) but the longest relative to its energy consumption; while the G- and R-units did not offer a comparative advantage over the C-unit in that regard (B > C > G > R). Nocturnal plasma melatonin and maturation rate decreased proportionally to the light-intensity provided using a range of technologies emitting distinct spectral profiles. Light-intensity rather than light-spectral composition appeared to be the prime parameter negatively affecting sexual maturation. Maximal suppression of maturation was observed in treatments depressing nocturnal plasma melatonin to a 1.2-fold but not to a 1.7-fold increase compared to day-time levels, confirming that a threshold level of light-irradiance is necessary to obtain the desired effect. Results suggest that this can be achieved under standard commercial practices by applying, over the photoperiod regime presently used, continuous artificial-illumination with an (electrical) energy consumption of 0.28 Wh m−3 generating a mean-irradiance of 0.012 W m−2 and providing a minimum volume of effective irradiance equivalent to 12 % of the rearing-environment. Such a low volume of biologically effective irradiance was likely sufficient due to the strong photic attraction already reported in Atlantic salmon. Maximal suppression of pre-harvest sexual maturation can be achieved in the Atlantic salmon on-growing industry using alternative light-technologies. Present data provides methods and threshold values favouring the implementation of photoperiod manipulation to suppress pre-harvest maturation at the most advantageous scale and cost.