EVALUATION OF AN EEL-TRAP SAMPLING METHOD FOR THE ASSESSMENT OF MIGRANT YELLOW EELS ANGUILLA-ANGUILLA (L) IN THE RIVER MEUSE

A sampling methodology using modified eel traps (100 x 40 cm empty set) installed in fish passes was evaluated for the assessment of migratory yellow eel Anguilla anguilla stock and population structure in the Belgian River Meuse in 1993. Up to 248 eels (mean size : 292 mm) were captured in a single trap immersed overnight. In a standardized context, the size of the sample captured in the trap was highly predictive (R = 0.998; 24 df) of the number of eels migrating through the fish pass. The eel traps were evaluated as non selective towards fish size within the size range of yellow eels (114 - 614 mm). The delay for checking the eel traps (2 min) fits the purpose of frequent and numerous samples. Applying this ''point migration sampling'' methodology on a large scale would allow a reliable assessment of yellow eel migration dynamics in regulated rivers like the River Meuse.