Spatial Dynamics of Demersal Fish Assemblages off the Korean Coast in the East Sea.

This study assessed variations in demersal fish assemblages with respect to the study site and water depth. Seasonal samplings from May 2018 to March 2019 were conducted along the northern (Ayajin, Goseong) and southern (Hupo, Uljin) sites of the East Sea off the Korean coast, using commercial gill nets. Samples were collected at depths of ~50, ~80, ~150 m across the study sites, with concurrent monitoring of water column structures. A total of 73 species and 6250 specimens were collected. Distinctive fish species compositions were observed according to the study site and depth. Although was the most abundant fish species in both Ayajin and Hupo, , , and were most predominant in Ayajin, whereas , , and were more prevalent in Hupo. In terms of depth layer, in Ayajin, dominated in both intermediate and deeper layers, with , , common in shallower depths. Conversely, in Hupo, , , and dominated across all depth layers, whereas and dominated in deeper and shallower depths, respectively. Significant influences of the study site and water depth on fish assemblage structures were observed due to variations in water temperature at the seasonal thermocline boundary.