Caspiomyzon wagneri (Kessler, 1870)

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 39-40

Caspiomyzon wagneri

Common name. Caspian lamprey.

Diagnosis. Distinguished from other species of lampreys in West Asia by: ● many small teeth in regular backwards-curved radiating rows / ○ all teeth low, blunt, button-shaped / ○ supraoral lamina short, with one, rarely

two closely connected teeth / ● supraoral lamina tooth blunt / ● infraoral lamina with 4–6 large teeth / ○ oral disc width less than body width / ○ ammocoetes with 53–68 trunk myomeres. Size up to 575 mm TL.

Distribution. Caspian Sea and most (even relatively small) tributaries. In West Asia, Kura drainage, up to Astara, lower Aras ( Azerbaijan), and coastal Caspian rivers east to Gorgan. In Iran, now restricted to a few rivers, between Sefid to Gorgan. Also found in European Caspian basin. Migrated to uppermost tributaries of Volga ( 1500 km), but spawn along all rivers where suitable substrate exists.

Habitat. Adults live in sea caught down to depths of 600– 700 m. Spawns in sections of rivers and streams with strong currents. Ammocoetes live in detritus-rich sand or clay sediments, selecting and changing habitats according to sediment size as they grow.

Biology. Anadromous; upstream migration of adults in autumn and spring. In Kura and Iran, autumn run begins in late October and peaks in December and January; spring run begins in mid-March to late May, with peak spawning migration in April (at 16°C) ( Iran). In shorter rivers, most individuals migrate in spring. Migration occurs at dusk landlocked populations in reservoirs in lower Volga must be confirmed.

Further reading. Berg 1949b,Holčík 1986 (biology); Renaud 2011 (morphology, biology); Coad 2016c (review); Abdoli et al. 2017 (migration pattern); Nazari et al. 2017 (biology).

and night, peaking about 2 hours after sunset and during daylight hours when water temperature rises to 13–14°C. Migrate 2–16 km per night. Spawn in pairs in March–June (rarely in July) when temperature reaches 13–23°C. Eggs laid in crescent-shaped nests made of gravel and small stones. Ammocoetes hatch in 8–10 days. Ammocoete stage lasts 2–4 years. Feeds on detritus and microorganisms. Metamorphosis begins in mid–July and lasts until October. After metamorphosis, juveniles migrate to sea until December of same year. Adults stay at sea for at least 17 months. In lower Volga, occurrence of small (about 190–310 mm TL) and large ( 370–550 mm TL) mature adults suggests that adults may feed one or two summers before spawning. Feeding behaviour unknown. Due to their fat content and abundance, dried C. wagneri were formerly used as candles in Russia.

Conservation status. LC; historically found in all Caspian rivers. Limited by dams to lower part of rivers. Discharged when caught in Iran due to religious reasons. Rare, with only a few remaining spawning sites in rivers draining from eastern Caucasus, where it might have stabilised at a low level. In Volga, a sharp decline was observed during the 20 th century. Potentially still abundant in Ural, but more information is needed at present. The status of