eDna and camera rivers (KB-24-005-030)

Wageningen Marine Research executes several fish monitoring programs in the (large) Dutch rivers and lakes for the ministry of economic affairs (LNV, WOT) and Rijkswaterstaat (RWS, MWTL). The programs use passive fishing gears (traps) especially for rare diadromous fish (e.g. eel, salmonids, lampreys) which presence in the lakes and rivers is limited to migration periods. The monitoring program are under pressure due to violations of contracted fisherman and alternatives need to be evaluated. This projects evaluates two techniques: Environmental DNA (eDNA) and video registration. eDNA may be an alternative for traps in monitoring species composition in Dutch
rivers and lakes. This project uses existing eDNA data collected in large rivers (4 locations and multiple samples) to compare results to traditional trap data (species composition). Also, video techniques may be a good alternative for counting fish and to measure fish length. Traps are still
needed to guide fish to a video registration system. However, fish can proceed migration after being registered. This project evaluates the possibility of video registration for, species identification, fish counts and length measurements