D. Fatin

Role of Eel Odour on the Efficiency of an eel, Anguilla anguilla, Ladder and Trap

The influence of eel odour on the efficiency of a freshwater eel ladder and trap was assessed during two glass eel and yellow eel springtime upstream migration seasons in the Vilaine estuary, France. This test consisted of alternatively directing the outflow from the trap holding bin, away from, or onto the trap access ladder and comparing catches. Catches were 1.4 higher for both glass eels and juvenile eels when the trap water was directed towards the pass. The experiment had little influence on predicting ladder catches when compared to the environmental parameters. The distance of detection of the scent was calculated to range between 0 and 5 m from the ladder.

Point sampling the abundance of European eel ( Anguilla anguilla ) in freshwater areas

The European eel population is in decline. Urgent management actions are required. To monitor their effect, we developed a fast sampling method, applicable in shallow rivers and tributaries. We compared the Carle & Strub estimator from 35 double pass electric fishing samples with Point Abundance Sampling by Electrofishing or PASE (24 point samples on average by section) which we adapted for the eel. The correlation between both methods was highly significant (r2=94%, p<0.001) for densities lower than 150 eels .100 m-2. PASE, being a cheaper sampling method, thus constitutes an efficient and cost-effective method for evaluating management actions and further biological studies.