Tidal barrage power plants generate power by virtue of the variations of the tidal elevation throughout the day. A tidal barrage consist of a dam, with turbines and sluice gates, that separates an inner basin from the sea, creating a hydraulic head between the inner basin water level and the sea water level. This head drives water through the turbines, transforming potential energy into mechanical (and subsequently electrical) energy. Given the mass of water contained within the basin, added to the slow dynamics of the tidal elevation, tidal barrages can be used as variable storage facilities. This provides flexibility to their operation, which can be exploited to shift the generation periods of the turbines present in the tidal barrage. As a result, the power generation profile can be adjusted to maximise output during hours when electricity prices are high. In this paper, we explore different objective functions to optimally operate the turbines and sluice gates of a tidal barrage, using a model based on the La Rance power plant. The aim is to include wholesale electricity prices, as well as estimated operational costs, in the objective function of tidal barrage operation, and analyse how these considerations impact overall energy generation, timing of power output, and pumping requirements.