| Résumé: |
Salmonid populations are widely spread around the world and they are of both economic and ecological importance. The preservation and restoration of salmonid populations is therefore fundamental. However, salmonid populations are stressed and threatened and so in decline in many parts of the world. Spawning habitat degradation is one of the causes of this decline.
Knowledge of spawning sites and the associated evolution through time is therefore fundamental to protect salmonid populations. At present, spawning areas are investigated and counted using visual records. However, this method has some weakness and it does not allow for a correct appreciation of the real extent of salmonid reproduction.
In this regard, this research develops a framework for using Unmanned Aerial Vehicles (UAVs) and SfM photogrammetry to detect salmonid redds through analysis of inter-epoch Digital Elevation Models (DEMs of Difference).
Our results suggest that the combination of UAVs and SfM photogrammetry and the consequent production of DEMs of Difference may detect more redds than the present method, allowing for a better and more precise detection of the spawning grounds.
Furthermore, we demonstrate that SfM-derived outputs might be used to extract useful information about spawning, such as redd density or female lengths, without disturbance of the spawning sites. |
Mémoire [46 Mo]