Fact File: Common Name(s): Three-spined Stickleback Scientific Name: Gasterostreus aculeatus Usual Size: Maximum 11cm, usually 4-6cms UK Record Weights from rod/line: Shore: Boat: MAFF Minimum Size: Shore: Boat:

Identification: Three sub-species of the Three-spined Stickleback occur in Europe: G. a. leiurus, G. a. semiarmatus and G. a. trachus. These differ in the amount of armouring and spines present, but the most common variety have 3 dorsal spines, 2 pelvic spines and a single anal spine. The dorsal and pelvic spines are protected from collapse by a pelvic girdle that connects them in a strong, crush-proof structure surrounding the body. All sub-species share a common body shape: the dorsal and ventral contours are curved and, (usually) evenly matched, the dorsal and anal fins are set well back along the body close to the long, thin caudal peduncle, and each pelvic fin is reduced to one spine. Colour varies due to location and conditions. Freshwater fish can be olive green above, fading to bronze or silver below; an overall bronze with grey mottling above; an overall bronze/green or a bright brassy colour. During the breeding season males develop a red breast. Sub-species variations. G. a. leiurus: the most lightly armoured variety, has no, or very few, body plates, one to three dorsal spines, pelvic spines may or may not be present. Mainly found in freshwater. G. a. trachus. The most heavily armoured, the body is fully plated and all spines are present. This variety is found in salt water, estuaries and is the main freshwater type in Eastern Europe. G. a. semiarmatus: this is intermediate between the two above having a partly plated body. Breeding: takes place March to August. Males become highly coloured to attract as many females as possible to lay their eggs in a nest he has previously prepared. Each female lays from 10 to 100 eggs and the male guards these and the resulting fry. Hatching takes up to 20 days. Habitat: found in lakes, rivers, ponds, estuaries and the sea. Food: carnivorous, they eat worms, insect larvae and fish. Range: common throughout Britain and Western Europe. Additional Notes: there are unconfirmed reports that four spined fish have been found in Northumberland and other parts of Britain.

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