Author: (Linnaeus, 1758)
FBname: River lamprey
Remark: Berg (1931) suggested that this species consists of two races; a normal form (<i>forma typica</i>) and a smaller praecox form. The praecox form has been reported from the Neva River and Lake Ladoga in the Russian Federation and the Severn River in England (UK) (Ref. 89241).
Comments: In fresh waters, in rivers, brooks, and lakes.  Anadromous, but some populations are permanent freshwater residents (e.g. Lough Neagh, Northern Ireland (UK); Loch Lomond, Scotland (UK); lakes Ladoga and Onega, Russian Federation) (Ref. 89241).  Amphihaline species (Ref. 51442). Metamorphosis takes place at a length of about 13 cm and they migrate to the sea (Ref. 51442). Most river lampreys live 4-7 years and reach 30-35 cm length (Ref. 88187). Females grow larger than males (Ref. 58137).  Adults spend 1-2 years at sea, often along the coast or in estuaries (Ref. 59043). They live on hard bottoms or attached to larger fish like cod and herring (Ref. 88174).  Adults are parasitic, feeding on fishes by sucking their blood and afterwards consuming the flesh (Ref. 1998).  Adults predatory on marine fishes from the end of July to October.  Trematodes and cestodes have been found in the intestine of prespawning adults at sea. (Ref. 89241). In autumn, adults commonly undergo reproductive migration from the sea to shallow middle or upper reaches of rivers and streams with strong currents (1.0-2.0 m/s in British rivers) and gravel bottoms (Ref. 51442, 59043, 88171). Spawning migration upriver (Vistula and Neman rivers) begins near the end of September in the Baltic Sea Basin. In tributaries to the Gulf of Finland (Narva, Neva, and Luga rivers), upstream spawning migrations occur twice yearly; once in summer-fall and once in spring. In the upper Rhine River, the spawning season is February to April; in England (UK) from April to May; and in the lower Neva River, Russian Federation, from early June to early July (Ref. 89241).  During reproductive migration and reproduction, adults do not feed but instead utilize their lipid reserves (Ref. 30578) and are known to undergo a considerable shortening of up to 27 per cent (Ref. 83507).  Fecundity is highly variable and ranges from 650 to 42,500 eggs/female; 10,000-16,000 eggs/female in Lake Ladoga. Communal spawning in the same redd by <i>L. fluviatilis</i> and <i>L. planeri</i> has been reported in the River Tywi Basin, Wales (UK), in April, at a water temperature of 11 °C. Both species participated in constructing a redd about 23 cm in diameter and 5-8 cm deep, consisting of pebbles, gravel and coarse sand (Ref. 89241). Spawning takes place in pre-excavated pits in river beds, its depth between 50-100 cm; after spawning the adults die (Ref. 51442). The blind ammocoetes are filter feeders of detritus and microorganisms; they live mostly buried in sand, silt or clay sediments for up to 4.5 years, often at the edges of rivers and streams where currents are slow (Ref. 51442, 59043, 88184, 88185). Sometimes they are found in substrates with submerged vegetation and plant debris (Ref. 12285). Ammocoetes may tolerate low oxygen levels but when burrows reach near anoxic levels, the larvae need to emerge from the substrate in order to survive (Ref. 88184).  Fisheries exist in England (UK), Finland, France, and the Russian Federation. In the 19th century, up to 450,000 adults yearly were used by the English fishing fleet as bait in the fisheries for <i>Gadus morhua</i> and <i>Psetta maxima</i>. In Finland, the catch in 1983 was 2.3-2.4 million individuals (about 100 t) for a value of $800,000 US. There are reports of intoxication through eating this species (Halstead 1967). The mucus and serum are poisonous and the flesh must be thoroughly washed and all the blood removed before consumption (Ref. 5504). Cooking method involves de-sliming, removal of heads and branchial regions, the rest of the body covered in sunflower flour, and cooked in sunflower oil (Ref.89241). Utilized fresh and smoked; eaten fried (Ref. 9988).