Use of RFID technology to evaluate fish passage through a 104-meter long culvert along the Durolle River

Abstract

In 2016, a hundred meters long culvert was fitted with a unique hydraulic device consisting of a rugged sole and pre-casted decelerators in order to restore the free movement of fish. This device was developed using hydraulic simulations to ensure favourable conditions of crossing for trout during flows between QMNA5 (value of the monthly low water flow reached by a river in a given year calculated for 5 years) and 2.5 times the module. The module corresponds to the inter-annual average hydrological flow over a reference period (at least 30 years of consecutive measurements). The actual functionality of this device was evaluated between 2017 and 2019 using RFID (Radio Frequency Identification) technology and following the movements of tagged trout using PIT-Tags (electronic devices that emit response when they receive an interrogation by radio). A total of 815 trout were tagged on a 1680-meter stretch downstream of the culvert. Ninety-nine (99) individuals were captured upstream and released downstream just below the culvert after tagging, in order to force an upstream migration behaviour. A fixed double RFID antenna structure set up immediately upstream of the culvert enabled us to detect fish that crossed the culvert throughout our study. In addition, seven mobile tracking campaigns took place to characterize the movement of the tagged trout along 2 km downstream of the culvert. The data from the antennae were analysed in relation to the individuals' characteristics and two environmental factors, namely hydrology and water temperature.