''Lampetra ayresii'' is a species of lamprey in the family

Petromyzontidae The northern lampreys (Petromyzontidae) are a family of lampreys. Northern lampreys have the highest number of chromosomes (164–174) among vertebrates. Genera * '' Caspiomyzon'' * '' Entosphenus'' * ''Eudontomyzon'' * ''Ichthyomyzon'' * ''La ...

. It is also called the river lamprey or western river lamprey. It is found in the eastern Pacific, specifically from

Tee Harbor, Juneau Tee Harbor (also known as The Harbor) refers to two adjacent populated places in the City and Borough of Juneau, Alaska. The area had a population of 32 in 1950. It is located northwest of Fairhaven and northwest of the main city of Juneau. ...

in Alaska to the

Sacramento ) , image_map = Sacramento County California Incorporated and Unincorporated areas Sacramento Highlighted.svg , mapsize = 250x200px , map_caption = Location within Sacramento ...

– San Joaquin drainage in California, USA. It can survive in both marine surface waters and freshwater lakes, rivers, and creeks. In freshwater, it is found typically in the lower portions of large river systems. It is a predatory fish and feeds on fishes in the size range of 10–30 cm. It feeds by attaching to prey using its round, sucker-like mouth. Adult western river lampreys typically grow to about

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

(TL), but can reach TL.

Description

Western river lampreys are noted by their long body, round mouth, and lack of jaws. On their disk-like mouth is two teeth, one tooth on the tongue, 3 points on each central lateral tooth plate, and no posterior teeth. They have no scales, and are typically dark brown in color, with yellow bellies and silver around the head, gill openings and lower sides. Western river lamprey larvae are very visually similar to

Pacific lamprey The Pacific lamprey (''Entosphenus tridentatus'') is an anadromous parasitic lamprey from the Pacific Coast of North America and Asia. It is a member of the Petromyzontidae family. The Pacific lamprey is also known as the three-tooth lamprey and ...

and

western brook lamprey The Western brook lamprey (''Lampetra richardsoni'') is a small (<18 cm), widely distributed, non-parasitic species of

jawless fish ...

larvae, and are virtually indistinguishable.

Life cycle

Western River Lampreys live on average for 6–7 years, spending most of their life in freshwaters and only living in marine waters for about 10 weeks. Starting their lives as an ammocoete (larva), they burrow into the stream bottom and survive as filter feeders. They can live like this for 2–7 years, after which they begin a metamorphosis into their macropthalmia (juvenile) stage. This metamorphosis starts in the months of July–April, and can take up to 9–10 months, the longest of any lamprey. After metamorphosis, they enter the ocean as adults between the months of May and July. They spend a parasitic feeding phase here for 10 weeks, during which they grow rapidly and reach their maximum size. After their feeding phase, they migrate back to fresh waters to spawning areas. They likely prefer spawning areas upstream and with gravel bottoms. Both sexes will move around stones to construct the nests. Each female will then lay around 11,400 to 37,300 eggs. Adults die after the eggs are laid and fertilized.

Diet

The river lamprey begins as a filter feeder in its ammocoete stage. During this time, they feed on algae and detritus. Parasitism begins in the adult stage and once it has reached 16.2 cm. During this time it feeds on 10–30 cm fishes, most commonly herring and salmon. To feed, it attaches to the back of its prey above the lateral line, using its round mouth. There it sucks on muscle tissue.

References

{{Taxonbar, from=Q5027623 Lampetra Fish of the Pacific Ocean Freshwater fish of North America Fish described in 1870 Taxa named by Albert Günther