Keanekaragaman Jenis dan Kepadatan Ikan Asli (Native) Serta Ikan Asing (Alien) di Ekosistem Danau Toba

Abstract

The research of the diversity of the species and the abundance of native fish and foreign fish (alien) in the Lake Toba ecosystem, Indonesia, was carried out in January 2022. The purpose of this study was to analyze the introduced fish species that had potential to become invasive fish and their relationships to the physical and chemical factors of the waters. The research was carried out at five stations selected by purposive sampling method based on the community activities around the station. Fish samples were taken using nets and then identified. The fishes were categorized and the data analyzed including density analysis, relative density, frequency of presence, diversity index, uniformity index, index dominance and correlation of water physico-chemical factors. The results showed that there were five types of introduced fishes. Diversity (H’) was moderate with a value range from 0,7330 to 1,1628, uniformity (E) was also in moderate range of values (0,5209- 0,7166). Based on the characteristics of invasive fish, the introduced fish that had the potential to become an invasive fish was Amphilophus citrinellus. The physico-chemical factors that strongly influence the density of the fish in the waters were light penetration, temperature and Phosphate contains.