Akademik Veri Yönetim Sistemi
Journal of Great Lakes Research, 2026 (SCI-Expanded, Scopus)
Understanding post-spawning behavior in potamodromous fishes is essential for conservation, particularly in hydrologically and ecologically unique systems. This study provides the first high-resolution acoustic characterization of pearl mullet (Alburnus tarichi) aggregations in Lake Van, a terminal, highly alkaline, predator-free lake. Hydroacoustic surveys, conducted during daylight hours in 2018 and 2020, revealed distinct aggregation types through multivariate analysis of 14 echo-derived descriptors. These types, interpreted as representing different life stages and behavioral states, reflected a seasonal continuum from post-spawning acclimatization to overwintering reaggregation. Nonparametric analyses showed that school types occupied significantly different thermal habitats. The spatial distribution of young-of-the-year (YoY) aggregations consistently aligned with colder, river-influenced nearshore zones, suggesting a prolonged acclimatization phase following lake entry. In contrast, subadults and adults formed thermally structured offshore schools, with changing compactness and biomass linked to foraging and overwintering transitions. These observations were broadly consistent with seasonal patterns described by local fishers, particularly regarding shifts in fishing locations and depths. The occurrence and density of YoY aggregations may also serve as a valuable indicator of spawning success and tributary health, factors increasingly threatened by anthropogenic pressures. Taken together, these findings position Lake Van as a unique natural system for studying the intrinsic drivers of fish aggregation in the absence of confounding ecological pressures.