Arctic Lamprey

The Arctic lamprey (Lethenteron camtschaticum) is a jawless fish with a circumpolar distribution across Arctic and sub-Arctic drainages of both North America and Asia, including river systems in Alaska, northern Canada, Siberia, and the Russian Far East. It is an anadromous, parasitic species, spending part of its adult life feeding on host fish in coastal and estuarine waters before migrating upriver to spawn. Some populations also include non-parasitic, freshwater-resident forms that mature and spawn without ever undertaking a feeding migration, a phenomenon seen in several lamprey species. Arctic lampreys belong to the ancient jawless fish lineage and are notable for tolerating some of the coldest freshwater and coastal environments of any lamprey species.

Arctic lampreys share the classic lamprey body plan and are best identified through a combination of range, size, and dentition.

Key field marks:

• Circular jawless sucker mouth with rows of small, sharp teeth
• Slender, elongated, scaleless body in dark bluish-grey to brown tones, fading to a pale silvery belly
• Two dorsal fins positioned near the tail, becoming more distinctly separated in breeding adults
• Seven round external gill openings on each side of the head
• Single nostril centered atop the head
• Adults typically 25-35 cm long

Arctic lampreys are distinguished from other circumpolar lamprey species largely by their extreme high-latitude range and by dental pattern details on the oral disc, best confirmed through close examination or genetic testing where ranges overlap.

Arctic lampreys occupy a circumpolar range spanning cold rivers, coastal waters, and estuaries throughout the Arctic and sub-Arctic regions of North America and Asia, including drainages of Alaska, the Yukon, Siberia, and the Russian Far East. Anadromous individuals spend a feeding period in coastal and brackish waters before migrating substantial distances upriver to spawn in gravel-bottomed streams with cold, clean, flowing water. Some populations remain permanently in fresh water without a marine phase. Larvae burrow into soft sediment in slow-flowing stream margins, where they can persist for several years in the cold northern climate before metamorphosing into free-swimming adults.

Arctic lampreys that undertake the parasitic marine phase attach to host fish using their sucker mouth to feed on blood and body fluids in coastal and estuarine waters, while some populations forgo feeding entirely and mature directly in fresh water. As with other lampreys, adults cease feeding once they begin their spawning migration, using stored energy reserves to travel upstream, sometimes over considerable distances in cold northern rivers. Spawning occurs communally over gravel substrate, with adults clearing small nest depressions before releasing and fertilizing eggs; death follows shortly after spawning in all individuals. Larvae live buried in fine sediment as filter feeders for an extended period suited to the slow growth rates of cold northern waters, playing a role in stream nutrient cycling before their eventual transformation into adults.