Snake pipefish (Entelurus aequoreus) intrusion as a new species into the Barents Sea ecosystem.

The snake pipefish Entelurus aequoreus is a member of the Syngnathidae family. The open water species is distributed in the eastern Atlantic, from the Azores to Iceland and Norway, including the Baltic Sea. Concentrations of snake pipefish were observed for the first time in the Barents Sea in August–October 2005, after which both their distribution area and average density have increased substantially in 2006. The area inhabited by these fish increased three-fold from 2005 to 2006, using data from pelagic trawling. The density in these areas rose from an average of 2.4 to 9.3 caught fish per nautical mile of trawling. However, using trawl data to measure abundance may not be the most adequate method due to little knowledge of the behavioural patterns of this fish species. Snake pipefish have historically usually been associated with warmer temperate waters, so it is interesting to note that the increase in numbers may coincide with exceptionally high sea surface temperatures for that time of year. We plan to investigate this relationship in further detail with collection of relevant data in 2007. Keywords: Snake pipefish; distribution pattern; Barents Sea: climate change