Analysing spatio-temporal patterns of non-native fish in a biodiversity hotspot across decades

Abstract

Aim: Analysing the spatio-temporal patterns and dynamics of non-native species is essential to understanding the mechanisms underlying successful invasions and developing effective management strategies. Yet, such analyses generally neglect the influence of receiving ecosystem types and non-native species sources (i.e. alien species, non-natives originating outside the concerned region; translocated species, non-natives introduced to locations outside their historical range within the concerned region). Location: Yunnan, China. Methods: We analysed long-term (1950–2022) spatio-temporal patterns and potential underlying dynamics of non-native fishes in a biodiversity hotspot (Yunnan, China), paying special attention to waterbody types receiving non-native species and comparing alien and translocated species. We did this through compiling a highly comprehensive occurrence dataset of native and non-native fishes. Results: We recorded 783 native species and 94 non-native species (49 alien species and 45 translocated species), which mainly belonged to the order Cypriniformes (52 species) and were introduced via purposes for advancing aquaculture. Most frequently encountered non-native species were either intentionally introduced aquaculture species or small-bodied fish unintentionally introduced via aquaculture activities. The richness and spatial ranges of non-native fishes increased consistently since the 1950s and demonstrated a pronounced change after the 2000s, with densely populated areas and the middle to lower reaches of large rivers being more profoundly affected. The number of records of translocated species exceeded the number of records of alien species after the 2000s. Lakes and reservoirs are hotspots for both alien and translocated species introductions, and watersheds with large areas in Yunnan (e.g. the Jinsha-Yangtze and Lancang-Mekong basins) contained more non-native fish. Main Conclusions: Our study highlights the need to consider invasion sensitivities of receiving ecosystems and pay special attention to intra-regional species translocations when developing prevention and management strategies against invasions of alien species, particularly in important biodiversity hotspots around the world.