. The Canadian field-naturalist. . FlGI ki I. Holotype of Lethenteron alaskense. Courtesy of the Canadian Museum of Nature, from Vladykov and Kott (1978) [male: total length 164 mm]. (A) Lateral view, (B) Enlargement of the head. (C) Enlargement of the tail. ( anada, control measures to eliminate popula- tions l parasitic lampreys are undertaken, but this is a non-parasitic species. Population Sizes and Trends There have been no population studies for this species and the information available at present is simple presence absence data. There is only one known ( anadian record despite i he pre
. The Canadian field-naturalist. . FlGI ki I. Holotype of Lethenteron alaskense. Courtesy of the Canadian Museum of Nature, from Vladykov and Kott (1978) [male: total length 164 mm]. (A) Lateral view, (B) Enlargement of the head. (C) Enlargement of the tail. ( anada, control measures to eliminate popula- tions l parasitic lampreys are undertaken, but this is a non-parasitic species. Population Sizes and Trends There have been no population studies for this species and the information available at present is simple presence absence data. There is only one known ( anadian record despite i he presence of the species in the Yukon Rivei system in Alaska. I Ins apparentl) disjunct Canadian population in the Mackenzie system is separated from the nearest known Yukon system record by nearly 1800 km andtheGreal Divide rhisanomoly might call into question the identity ol the I McAllister, ( anadian Museum ol Nature, Ottawa. Ontario; pei si mal communis a) ion) Buchwald (l%K) indicated that Arctic Lamprey are found in the Mackenzie River System, Great Slave Lake and the Slave River as far upstream as Fort Smith. He also recognized anadromous and non-anadromous forms ol the species and the greater potential size o\ the former. Hiese differences were apparently noticeable in the Slave River (Buchwald 1968) and have also been reported in the Yukon River (Heard 1966). I he presence ol the larger, parasitic form so fai upstream furthei clouds the issue and there itoes not appear to be any new e> idence to clarify it. I he parasitic nature and larger size of the Arctic 1 amprey would weigh in favoui ol its distinctness from the American Brook Lamprey. Also, . onions lampreys arc known to migrate long distances between fresh and saline waters and to utilize freshwatei habitats as demonstrated by the Sea I amprey (Petromyzon marinus) invasion ol the (ileal I Please note that these images are extracted from scanned page images that may have been digitally enhanced for r
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