Bresle River Long Term Observatory

Monitoring of migratory fish populations (salmon, lampreys, eel, etc.) is based on a two-trap system. Fish are captured as they enter or leave the river after their marine life stage.

The monitoring station consists of two facilities, that are located at Eu (Seine-Maritime department), and Beauchamps (Somme department), (3 and 15 km from the sea, respectively).  Capture-mark-recapture methods, enable upstream and downstream migration in the river to be quantified. Fish are trapped throughout the year.

Trapping

Upstream and downstream migrations of salmon and sea trout are quantified annually using capture-mark-recapture methods.

•  Trapping upstream-migrating adult salmon and sea trout:

                      a) main trap (P1), for capturing and tagging upstream-migrating individuals, at Eu

                      b) secondary trap (P2), for recapturing and monitoring adults returning to the sea after spawning, at Beauchamps

• Trapping downstream-migrating juvenile salmon and sea trout:

                      a)  main trap (P1), for capturing and tagging, at Beauchamps

                       b) secondary trap (P2), for recapture and monitoring, at Eu

Upstream-migrating juvenile eels, (colonising migration) are captured at Eu, while, downstream-migrating adults eels (spawning migration) are captured at Beauchamps (P1) and then at Eu (P2). Tagging and recapture surveys to estimate upstream migration rates were conducted from 2008-2010, but the data collected to date are not sufficient to estimate them.

	Salmon Monitoring of salmon populations since 1982	See report
	Trout Monitoring of trout populations since 1982	See report
	Eels Monitoring of eels populations since 1982	See report