FishDrop: Estimation of reef fish population density and biomass using stereo cameras

Underwater Visual Census for fish population density and biomass measurements is the standard method for monitoring the health of a marine environment. Conducted within reef areas, it provides important documentation over time quantifying the success of reef protection and rehabilitation initiatives. The monitoring results are crucial to the formulation of strategies to improve reef resilience and increase productivity of reef fish communities. Typically this census is done by a fish expert swimming along a transect with the aid of a SCUBA. Previous attempts at incorporating videos in fish census aimed to reduce dive hours and for permanent transect records. However, subsequent manual analysis of the collected video data is tedious and time consuming. We propose a semi-automated process of performing fish census which otherwise requires high level of domain knowledge and expertise. Divers with minimal knowledge of fish can obtain high quality population and species distribution measurements using a stereo camera rig and fish video analyzer software that we have developed. Our system has two major components: a camera rig and software for fish size, density and biomass estimation. The camera rig consists of a simple stand on which one to four pairs of stereo cameras are mounted to take videos of the benthic floor for a few minutes. The collected videos are uploaded to a server which performs stereo analysis and image recognition. The software produces video clips containing estimates of fish size, density and species biodiversity and a report in csv format containing information about the individual fishes for further end user analysis.