Assessment of the nursery environment and distribution of Ayu, Plecoglossus altivelis (Actinopterygii, Osmeriformes, Plecoglossidae), in Vietnam

The distribution of larvae and juveniles of Ayu, Plecoglossus altivelis (Temminck et Schlegel, 1846), is shaped by intricate interplays involving environmental variables and anthropogenic influences. The intricate interplay and equilibrium among these factors will govern the distribution and abundance of Ayu fish larvae and juveniles in estuarine settings. In this investigation, a hybrid Ant Colony Optimization-Adaptive Neuro-Fuzzy Inference System (ACO-ANFIS) model was utilized to enhance the precision of Ayu fish larvae and juvenile’s occurrence estimation for the period from 2021 to 2022. The outcomes evinced that the hybrid model displays strong predictive capabilities, with R 2 test > 0.75, and AUC > 0.79. Among the environmental parameters, temperature, salinity, and turbidity exhibit the highest correlations with Ayu fish occurrence, with R values of 0.47, 0.54, and 0.40 for the Ka Long estuary, and 0.49, 0.50, and 0.42 for the Ba Lat estuary, respectively. The presence of Ayu species is limited to northern Vietnam, albeit with a declining pattern from the Ka Long estuary to the Ba Lat estuary. The study’s outcomes propose that the identification of suitable habitats and the cartography of fish distribution are invaluable for scrutinizing the ramifications of natural and anthropogenic influences on species distribution.