Deploying an acoustic telemetry network in a large waterway. Study of the habitat and unhindered circulation of fishes.

Abstract

Some of the projects of the hydro-ecology team of the UR HYCAR unit are designed to provide operational assistance to the managers of aquatic environments to better rank their restoration activities. In particular, the CONSACRE (Ecological continuity of the Seine and interest of actors for its restoration) project is aimed at estimating the state of un hindered fish circulation (ecological fish continuity) on the Seine River as from the first dam between the river and the sea (Poses in the Eure department) and in the successive reaches until Paris. The analysis of this unhindered circulation is based on the acquisition of behavioral ecological knowledge essential for studying species impacted by human activities. It relies on new technologies and in particular acoustic telemetry which, although mostly used in marine and estuary environments, can respond to the constraints of large waterways. This article describes the technical elements involved in implementing a network of hydrophones that provide reliable detection data on fishes in a complex waterway. This network must fulfil the double objective of studying the utilization of habitats and the successive crossings of several navigation structures, by using the trajectories of 7 species of migrating and resident fishes. Our experiment shows the importance of carrying out detection tests with the network deployed to enable optimizing adaptation to the morphological and regulatory constraints linked to navigation and the uses of a waterway. The data collected by the hydrophone network have allowed us to study the individual trajectories of different species, and in particular to assess the efficiency of crossing systems (fish passes) and the use of new passageways such as locks.