Petromyzon marinus, Linnaeus, 1758

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 43

Petromyzon marinus

Common name. Sea lamprey.

Diagnosis. Distinguished from other species of family in West Asia by: ● adults grey to yellow with dark-brown blotches, no blotches in juveniles / ○ supraoral lamina short, with two adjacent teeth / ● infraoral lamina with 7–8 large, sharp teeth / ○ oral disc wider than body width / ○ many small teeth on oral disc, in regular backward-curved radiating rows / ○ all teeth sharp / ● 66–75 trunk myomeres / ○ ammocoetes with black pigment on caudal. Size up to 1200 mm TL.

Distribution. Occurs very irregularly in Mediterranean rivers in Türkiye. Widespread on both sides of North Atlantic, north to Iceland, and along Norwegian coast to Barents Sea (Ura, Kola Peninsula). North Sea, Baltic, and western and central Mediterranean basins very rare in eastern Mediterranean and Baltic basins. Several land-locked populations in North America.

Habitat. Adults at sea offshore. Spawns in strong-current habitats of rivers and streams. Ammocoetes in detritus-rich sand or clay sediments.

Biology. Anadromous, parasitic. Adults migrate to rivers in autumn and winter.Spawns in pairs,April–July,mostly in May and early June,when temperatures reach at least 15°C.Spawning individuals stop their normal daylight avoidance response and breed on sunny days.Male dig a shallow nest in areas with strong currents. Ammocoete stage lasts 5½–7½ years. Feeds on diatoms and detritus, metamorphoses at 130–150 mm TL in late summer, and migrates to sea. Adults parasitise various fish species at sea,even whales and other cetaceans.It usually does not kill its hosts but feeds on small amounts of blood and body fluid from a single host for several days. Adults feed for about 3 years before migrating to spawning grounds.

Conservation status. LC; rare but widespread. Populations in Europe, which had declined due to pollution, have recovered since the 1980s but appear to be declining again in recent years.

Remarks. In 1921, 90 years after opening of the Welland Canal, the Lake Ontario population entered other Great Lakes of North America. Combined with other factors, this caused a sharp decline in many native species and the extinction of three endemic coregonids.

Further reading. Potter & Osborne 1975 (identification); Hardisty 1986b (biology); Rodríguez-Muñoz et al. 2004 (genetics); Çevik et al. 2010 (record in Türkiye).