When you have a timed mission, there is a way of stopping the clock in order to wait for something to finish; (i.e growing some vegs) Start the clock, do what you need to do, then once all you have left is that growing veg, go to the nearest beach and start fishing. The trick is to not catch the fish but not to let it go either! Caution: When using this trick, make sure you stock up loads of food as it is Life consuming!