Alien Rainbow Trout Oncorhynchus mykiss in the Balkhash Basin (Kazakhstan, Central Asia): 50 Years of Naturalization
Mamilov N.S. Tursynali M. Khassengaziyeva G.K. Urban J. Bartunek D. Sharakhmetov S.E. Sapargaliyeva N. Urgenishbayeva Z. Kegenova G.B. Kozhabaeva E. Baimukanov M. Levin B.
October 2024Multidisciplinary Digital Publishing Institute (MDPI)
Animals
2024#14Issue 20
Rainbow trout, or mykiss (Oncorhynchus mykiss), is one of the most popular species used in aquaculture and has been naturalized worldwide, including in the Central Asian Balkhash basin, which has unique aboriginal fish fauna. Both rainbow trout from European farms and wild mykiss from Kamchatka were introduced to some mountain lakes and rivers of the Balkhash basin about 50 years ago. This study investigates the current distribution and life history traits of the alien species and its possible impact on the local fish fauna. This study showed that the rainbow trout occupies various habitats in the Ili River basin: mountain lakes, fast-flowing mountain rivers, and lowland rivers with slow currents and warm water (up to +27 °C). Rainbow trout from European fish farms dominate the mountain Middle Kolsay Lake, while the wild trout from Kamchatka occupies the small Ulken Kokpak River. Both co-occur in the Chilik River. Contrary to that in other regions, the distribution of rainbow trout in the Balkhash basin remained almost the same after their introduction. Broad intrapopulation variability in terms of size, growth rate, and maturation age was revealed, apparently as a result of adaptation to the new environment and intrapopulation competition. In particular, the growth rate has decreased, but life span, surprisingly, has increased as compared to the originally introduced fish. Intrapopulation variation in growth and maturity patterns was also noted. Differences in skin coloration between highland (cold-water) and lowland (warm-water) populations were discovered. The feeding mode of naturalized trout is insectivorous (insect imago), indicating that it occupies its own niche in the local fish communities. The largest population of rainbow trout was recorded in the Lower Kolsay Lake, lowering the population of native fish species, while in other localities, no negative impact on local fish communities was recorded.
competition , diet , fish introduction , grow , life history , population , skin hue , thermal tolerance
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Department of Biodiversity and Bioresources, Faculty of Biology and Biotechnology, Al-Farabi Kazakh National University, Al-Farabi av., 71, Almaty, 050040, Kazakhstan
Laboratory of Signal and Image Processing, Institute of Complex Systems, Faculty of Fisheries and Protection of Waters, CENAKVA, University of South Bohemia in Ceske Budejovice, Zámek 136, Nové Hrady, 373 33, Czech Republic
Institute of Hydrobiology and Ecology, Irgeli Village, Rakhmetov Str., 58/1, Almaty, 040916, Kazakhstan
Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Yaroslavl Prov., Borok, 152742, Russian Federation
A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Leninsky pr., 33, Moscow, 119071, Russian Federation
Department of Biodiversity and Bioresources
Laboratory of Signal and Image Processing
Institute of Hydrobiology and Ecology
Papanin Institute for Biology of Inland Waters
A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences
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