Blackcurrants fruit on the wood that grew a year previously. Therefore hard pruning means you may be at risk of removing the fruiting wood. For blackcurrants it is recommended to remove a third of the bush to the ground every year, always removing the oldest third. Gooseberry bushes are a little more difficult as they grow on spurs, so avoid cutting everything back and focus on removing whole branches. Additionally try to cut down on feeding the bushes, slowing growth and therefore minimising the necessity to prune.