A novel way of catching piper is to wade a sheltered bay at night with a lantern or torch. They will come right up close to you and they are very easy to scoop up with a little hand net.
Use the small ones for bait but keep the larger ones for supper; they are one of the tastiest fish around. Clean them and poke the bill through the body down towards the tail so it forms a doughnut shape. Coat with flour and quick fry until they are a nice golden brown then straighten the fish up and the whole spine will separate from the flesh.