Akademik Veri Yönetim Sistemi
Marine Pollution Bulletin, cilt.220, 2025 (SCI-Expanded, Scopus)
Glass eels (Anguilla japonica) migrate to estuaries for recruitment, but estuarine barrages obstruct their migration, challenging eel conservation and management. In this study, the Nakdong River estuary was selectively opened by regulating sluice operations to mitigate physical disturbance of glass eel migration. We conducted extensive surveys at both the upstream and downstream areas of the estuarine barrage using a fishing boat equipped with a lift net (2 × 2 mm) over four consecutive years (n = 42). In 2024, an alternative survey was performed at the boat pass of the estuarine barrage to assess the impact of the fish lock method. Field surveys in the upstream and downstream area of the estuarine barrage revealed that glass eel abundance was concentrated in the downstream area, particularly near freshwater discharge outlet, regardless of estuary reopening. During estuary reopening, glass eels became more widely dispersed, with a significantly higher catch per unit effort (CPUE) in the upstream area. Generalised additive models (GAMs) indicated that CPUE at the downstream area was influenced by environmental variables such as migration timing and salinity, whereas CPUE in the upstream area was associated with tide-related factors such as tidal range, seawater intrusion, and reopening duration. Additionally, observations at the boat pass highlighted the fish lock method as a significant factor affecting glass eel abundance, with efficiency depending on tidal range. Our findings emphasise the importance of adaptive barrage operation strategies, such as synchronising sluice openings with migration periods and optimising tidal conditions, to improve glass eel recruitment and connectivity between habitats.