A Major Increase in Snake Pipefish (Entelurus aequoreus) in Northern European Seas since 2003: Potential Implications for Seabird Breeding Success

Abstract

Since the early 2000s routine fish surveys have recorded increasing numbers of snake pipefish, Entelurus aequoreus, in the northeast Atlantic. Fishermen and divers have also commented on this increase and pipefish have started to appear in the diet of seabirds and other marine predators. This paper collates information from these diverse sources and assesses the current status of snake pipefish. We found compelling evidence of a dramatic and continuing increase in the abundance of snake pipefish starting around 2003. The population is probably still increasing rapidly and expanding northwards to Spitzbergen and the Barents Sea. In 2004 and 2005 snake pipefish were also recorded in the diet of many species of seabird, breeding in colonies around the coast of the UK, and in Norway, Iceland and the Faeroe Islands. Information on the nutrient value of snake pipefish is currently lacking but their rigid, bony structure makes them difficult for young seabirds to swallow and there are numerous records of chicks choking to death. Thus for seabirds, at least, it appears unlikely that increased abundance of snake pipefish will provide a useful alternative prey during the breeding season. The reason for the rapid and dramatic increase in numbers of snake pipefish is currently unclear but such events are characteristic of marine ecosystems and will almost certainly have an effect on food web dynamics.