Petromyzon marinus (Sea Lamprey)
Sea lamprey are the largest of the three species of Petromyzon found in Scotland and the only species recorded in the Outer Hebrides.
Bern Convention Appendix 3
Annex II of the EC Habitats Directive
OSPAR Convention
UK Biodiversity Action Plan priority species
Scottish Biodiversity List: Species of Principal Conservation Importance in Scotland
Distinguished from the other European lampreys by its larger size (head-body length at spawning: over 45 cm), the marbling of the greyish-green back, and two, widely separated, dorsal fins.
After spending 18-24 months feeding at sea, the adults migrate up rivers in March and April, with spawning taking place during the following spring and early summer. Mating occurs in pairs, unlike the other lampreys in which a female is mated by a succession of males. The female lays up to 300,000 eggs into a depression in the river bed created by the male.The alternative common name of stone sucker may have arisen from the habit of males of removing stones with the mouth during spawning when they create a depression in the river bed by wriggling.
After hatching, the ammocoete larvae burrow into the sediment where they live for three to five years, feeding by filtering organic particles from the water. During metamorphosis, the eyes and the sucker-like mouth develop and the adults then migrate to the sea where they adopt a parasitic lifestyle, feeding by attaching to the bodies of large fish with the mouth and rasping away at the flesh. They remain in the sea for a few years and then return to freshwater in order to spawn. The digestive organs degenerate of the adults degenerate during migration and shortly after spawning they die.
