Spawning Migration Period of European Eel (Anguilla anguilla L. 1758) in Güllük Lagoon (Türkiye) Inferred from CPUE Analysis

The European eel (Anguilla anguilla) is a critically endangered catadromous fish species. Determining the timing of their spawning migration is crucial for effective conservation of this species. In this study, we aimed to identify the spawning migration period of European eels caught in Güllük Lagoon (Muğla, Türkiye). For this purpose, catch per unit effort (CPUE, defined as the number or biomass of eels caught per fishing gear per unit time) was calculated for yellow and silver individuals. Monthly changes in CPUE were analyzed using fyke nets, with samples collected by local fishermen between February 2022 and January 2023. The results revealed that CPUE for silver eels reached its peak in November, and silver individuals were present in the catch composition until the end of January 2023, indicating that the spawning migration likely occurs between November and February. Furthermore, CPUE values declined by almost tenfold compared to those reported in a similar study conducted in the region approximately 15 years ago. These findings confirm the migration period and also highlight the increasingly critical status of this local subpopulation, underlining the urgency of conservation actions.