A. S. Batubara, M. Muliari, B. Manurung, H. Sipahutar, Y. Akmal, I. Irfannur, S. Maulizar, F. M. Nur, Y. E. Ritonga, K. Lubis
Risk Assessment of Introduced Fish Species as A Biodiversity Mitigation Effort in Lake Toba, North Sumatra, Indonesia. Batubara, A. S., Muliari, M., Manurung, B., Sipahutar, H., Akmal, Y., Irfannur, I., Maulizar, S., Nur, F. M., Ritonga, Y. E., Lubis, K. — Lake Toba’s environment and ichthyofauna are degrading due to human activities and the introduction of invasive fish species. Studies are needed to identify species, distribution patterns, densities and risks of introduced fish species, and these studies must be conducted using scientific and measurable approaches. Research was conducted in Lake Toba, North Sumatra, Indonesia, from June to August 2024, at ten research locations. The research employed an exploratory method, measuring parameters such as population density, the Shannon-Wiener diversity index (H’), the evenness index (E), and the Simpson dominance index (C). Furthermore, this research measures the risk of invasiveness using the Fish Invasiveness Screening Test (FIST). Nine introduced fish species have become established in Lake Toba, including Amphilophus labiatus (Günther, 1864), Aplocheilus panchax (Hamilton, 1822), Cyprinus carpio Linnaeus, 1758, Mystacoleucus padangensis (Bleeker, 1852), Oreochromis mossambicus (Peters, 1852), O. niloticus (Linnaeus, 1758), Poecilia reticulata Peters, 1859, Puntigrus tetrazona (Bleeker, 1855), and Xiphophorus helleri Heckel, 1848. Population density values show that P. reticulata has the highest average value reaching 6.02 ind/m2, followed by A. labiatus 2.21 ind/m2, M. padangensis 0.21 ind/m2, O. niloticus 0.14 ind/m2, P. tetrazona 0.08 ind/m2, X. helleri 0.03 ind/m2, and 0.01 ind/m2 in A. panchax, C. carpio, and O. mossambicus, respectively. Diversity index analysis show low diversity (mean of 0.7), evenness index shows unstable community (mean of 0.46), and Simpson dominance index shows the presence of a dominant species (mean of 0.63). The results of the FIST analysis show that five introduced fish species are in the high risk category, three species have a moderate risk and one species has a low risk. O. niloticus, A. labiatus, C. carpio, O. mossambicus, and P. reticulata have a high risk for ichthyofauna diversity and in fact cause low diversity in Lake Toba. © Publisher Publishing House "Akademperiodyka" of the NAS of Ukraine, 2025. The article is published under an open access license CC BY-NC-ND (https://creativecommons.org/licenses/ by-nc-nd/4.0/)
Department of Biology, Faculty of Mathematics and Natural Sciences, Universitas Negeri Medan, Medan, 20221, Indonesia; Department of Marine Science, Faculty of Agriculture, Universitas Malikussaleh, Aceh Utara, Indonesia; Department of Biology Education, Faculty of Mathematics and Natural Sciences, Universitas Negeri Medan, Medan, 20221, Indonesia; Department of Aquaculture, Faculty of Agriculture, Universitas Almuslim, Bireuen, Indonesia; Graduate Program of Biology, Faculty of Biology, Universitas Gadjah Mada, Yogjakarta, Indonesia; Research Center for Biosystematics and Evolution, National Research and Innovation Agency (BRIN), Cibinong, 16911, Indonesia; Biology of North Sumatra's Nature Lovers, Medan, Indonesia
