June is the month that many greater pipefish enter the Wadden Sea from the North Sea. They come here to spawn. In the case of pipefish, one could call it ‘giving birth’ because they leave the male brood pouch as a fully-grown fish. In May the female lays her eggs in this brood pouch where they are fertilised by the male. After a few weeks they are full-grown and are released at a length of around 30 mm. In early summer the Wadden Sea is full of larvae of shrimps, crabs and mysids. This is good food for the young pipefish. They eat them by extending their tube-like mouth in the right direction and inhaling the larvae with the water. In this way they can eat a lot of prey in a short time and grow very quickly so that they are ripe to spawn by the following year. It is said that they often spawn more than once per year, so one can still find young pipefish in the autumn.
A well armoured body
The body of the pipefish is well armoured, which means birds are not keen to eat such ‘bony’ prey. As a relatively slow swimmer, the pipefish is only able to avoid predation by being a difficult fish. They live by the saying 'we can’t outrun ‘em, but we can outsmart ’em'. Some years the normal prey items of seabirds are scarce, and especially in years when sand eel is not common, nearby colonies of seabirds chose pipefish as a substitute. This happened with another species of pipefish, the snake pipefish, 10 years ago. At that time researchers realised just how many of these fish actually live in the sea. Because they are long and slender and can pass through standard-sized mesh, they are seldom caught with nets.
A well-known family member of the pipefish is the sea horse. It has the same way of living and the only difference is the way the tail is turned up, which it uses to attach itself to seaweed.