Mass occurrence of snake pipefish in the Northeast Atlantic: Result of a change in climate?

In 2004, a sudden mass occurrence of snake pipefish Entelurus aequoreus took place in the Northeastern Atlantic and the abundance has been increasing since. Before 2004, snake pipefish were mainly found in coastal areas and have been reported only occasionally in oceanic waters. The oceanic form lives free in the water column while the coastal form is found among sea weeds or in sea grass beds. Abundance indices (numbers per hour fishing) from inshore surveys have remained at the same level, while those from offshore surveys show a very strong increase since 2004. The length distributions differ significantly between surveys, with coastal snake pipefishes being larger. Although the outward appearance of the coastal pipefishes seems different from the pelagic specimens, no differences were found when comparing taxonomic features. Apart from appearance the habitat is different for the two types of snake pipefish