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

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, nonnatives 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.