East Siberian grayling
Template:Short description Template:Speciesbox
The East Siberian grayling (Thymallus pallasii)<ref name=FB>{{#invoke:Cite taxon|main|fishbase|genus=|species=|subspecies=}}</ref> is a grayling in the salmon family Salmonidae.<ref name = "COL">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name = "YD">Yury Valentinovich Dyldin. A review of the genus Thymallus</ref> <ref name = "col480571">Berg, L.S. (1962) Freshwater fishes of the U.S.S.R. and adjacent countries. volume 1, 4th edition., Israel Program for Scientific Translations Ltd, Jerusalem. (Russian version published 1948).</ref> Males can reach a size of Template:Convert.<ref name=FB/>
Distribution
East Siberian grayling was first described to be found at the Kolyma River basin by Peter Simon Pallas. Its distribution range is still insufficiently understood, and is believed to include most of the rivers flowing to the Arctic coast eastward from the Khatanga River, across the East Siberian Plain, and further east to easternmost Siberia, including the rivers in the Chukotka Peninsula as well as rivers of the Sea of Okhotsk basin, such as the Ola River in the Magadan Oblast and the Kukhtuy in Khabarovsk Krai.<ref name = "YD"/><ref>Template:Cite book</ref>
Description
Thymallus can be distinguished by their elongated, often cylindrical body, greatly enlarged dorsal fin, small mouth and striking dorsal coloration. Adult dorsum color ranges from dark purple to blue/black, and claret red spots are sometimes observed above ventral fins and on the caudal peduncle. Adults can have dark lateral spotting, and the lower caudal lobe is often longer than the upper lobe <ref>McClane, A. J. (1978). McClane’s Field Guide to Freshwater Fishes of North America. Henry Holt</ref><ref>Shestakov, A. V., & Grunin, S. I. (2022). Species Composition and Features of Fish Biology of Thermal Mineral Springs of the Arctic River Gilmimliveem (East Chukotka). Inland Water Biology, 15(1), 54–61. https://doi.org/10.1134/S1995082922010114</ref> East-Siberian grayling were first described by Valenciennes (1828) and were described as having a less acute pectoral fin, radiating streaks on the operculum, longer dorsal fin rays, and narrower maxillae than other Thymallus sp..<ref>Cuvier, M., & Valenciennes, M. (1828). Historie Naturelle des Poissons</ref> Additionally, Thymallus sp. can be distinguished by the extension of the upper jaw beyond the anterior of the eye but not to the midpoint of the eye.<ref>Knizhin, I. B., Kirillov, A. F., & Weiss, S. J. (2006). On the diversity and taxonomic status of graylings (Thymallus Thymallidae) from the Lena River. Journal of Ichthyology, 46(3), 234–246. https://doi.org/10.1134/S0032945206030039</ref><ref>Shestakov, A. V., & Grunin, S. I. (2022). Species Composition and Features of Fish Biology of Thermal Mineral Springs of the Arctic River Gilmimliveem (East Chukotka). Inland Water Biology, 15(1), 54–61. https://doi.org/10.1134/S1995082922010114</ref> Thymallus sp. including T. pallasii often have plastic phenotypes distinguished by differences in relative length, rows of spots on dorsal fins and caudal peduncle color.<ref>Knizhin, I. B., Kirillov, A. F., & Weiss, S. J. (2006). On the diversity and taxonomic status of graylings (Thymallus Thymallidae) from the Lena River. Journal of Ichthyology, 46(3), 234–246. https://doi.org/10.1134/S0032945206030039</ref>
Reproduction and development
Thymallus spawn polygamously in the spring in rivers and lakes, with males guarding independent territories. Eggs are laid in shallow areas of clear, fast-moving streams with rocky or sandy bottoms, and incubate for between 13 and 18 days before hatching. Adults do not perform any parental care. Juveniles reach sexual maturity at around 2 – 6 years old, and maximum sizes recorded are 515 mm and 488 mm, for females and males, respectively. Grayling live up to 22 years, and are known to have complex local migrations corresponding with the seasons.<ref>Stewart, D. B., Mochnacz, N. J., Reist, J. D., Carmichael, T. J., & Sawatzky, C. D. (2007). Fish life history and habitat use in the Northwest Territories: Arctic grayling (Thymallus arcticus), Central and Arctic Region Fisheries and Oceans Canada Winnipeg</ref>
Behavior, diet and predation
Adults are visual predators and stay in depths of 110 – 152 cm. Grayling feed primarily on aquatic and terrestrial insects, aquatic insect larvae, fish, small mammals, and crustacean zooplankton, and often require clear streams to feed.<ref>Papakostas, S., Vøllestad, L. A., Primmer, C. R., & Leder, E. H. (2010). Proteomic profiling of early life stages of european grayling (Thymallus thymallus). Journal of Proteome Research, 9(9), 4790–4800. https://doi.org/10.1021/pr100507s</ref><ref>Stewart, D. B., Mochnacz, N. J., Reist, J. D., Carmichael, T. J., & Sawatzky, C. D. (2007). Fish life history and habitat use in the Northwest Territories: Arctic grayling (Thymallus arcticus) Central and Arctic Region Fisheries and Oceans Canada Winnipeg</ref> East-Siberian grayling predators include humans, as well as pike (Esox sp.).<ref>Stewart et al., 2007</ref>
Economic importance and conservation status
While Thymallus do not have significant commercial economic importance, they are culturally relevant and are harvested massively by anglers.<ref>Koskinen, M., Ranta, E., Piironen, J., Veselov, A., Titov, S., Haugen, T., Nilsson, J., Carlstein, M., & Primmer, C. (2000). Genetic lineages and postglacial colonization of grayling ( Thymallus thymallus , Salmonidae) in Europe, as revealed by mitochondrial DNA analyses. In Molecular Ecology (Vol. 9).</ref> Additionally, grayling require rocky or sandy bottom streams and well oxygenated water- giving them important potential as an indicator species.<ref>Dyldin, Y. V., Hanel, L., Romanov, V., & Plesnik, J. (2017). A REVIEW OF THE GENUS THYMALLUS (PISCES: SALMONIFORMES, SALMONIDAE, THYMALLINAE) WITH TAXONOMIC NOTES. https://www.researchgate.net/publication/320717215</ref> Thymallus pallasii are considered a species of least concern, and recent genetic work indicates T. pallasii may be part of a larger group, T. arcticus sl., composed of T. mertensii, pallasii and signifer.<ref>Weiss, S. J., Duarte, &, Gonçalves, V., Secci-Petretto, G., Englmaier, G. K., Gomes-Dos-Santos, A., Denys, G. P. J., Persat, H., Antonov, A., Hahn, C., Taylor, E. B., & Froufe, E. (2020). Global systematic diversity, range distributions, conservation and taxonomic assessments of graylings (Teleostei: Salmonidae; Thymallus spp.). https://doi.org/10.1007/s13127-020-00468-7/Published</ref>