Sticklebacks

Sticklebacks can be found in a variety of disparate habitats within the temperate and arctic zones of North America, Asia and Europe. As their name suggests, sticklebacks are laterally depressed with well developed dorsal and pelvic spines. The body may be covered with a variable number of boney plates (or scutes), and these may, in some instances, be absent. Spineless sticklebacks occur in calcium deficient systems and the loss of spines may also be an evolutionary adaptation to reduced predation risk.

The British spineless stickleback morphs are referred to as 'anomalous'. These fish have no pelvic spines, a varying number of dorsal spines and often no pelvic girdle. Sticklebacks within the 'anomolous' clade occur in: Southern and Northern extremes of the European distribution of the species; Pacific north west coast of the USA, on certain offshore islands of British Colombia Central and Southern California.

Within the British Isles, the distribution of spineless sticklebacks populations are restricted to the Western Isles and Northern Scotland.

The conservation status of spine-deficient sticklebacks

The ubiquitous nature of three-spine sticklebacks within the British Isles has meant that common forms have received no conservation status. Only those fish which display some degree of ecological or genetic divergence, such as the spineless morphotypes are considered to be of any conservation value. Spineless stickleback morphs are located in two SSSI's in Scotland, Loch Ruthven (East Highland) and Loch Druidibeg (Western Isles) - but not as designated features of these sites.

9-Spined stickleback

The nine-spined stickleback is the smallest freshwater fish in Britain. Unlike the three-spined variety, nine-spined sticklebacks are not widely distributed in Scottish freshwaters and is most commonly associated with slow moving waters in the south and western parts of the country. They can also be found in some coastal and estuarine environments.

This is a poorly studies species and despite its apparent restricted distribution within Scotland and other parts of Britain, it is not considered to be under threat.