Rehabilitation of whitefish fisheries in lakes Geneva and Bourget during the eutrophication period: assessing socio-economic impacts through large collaborative research

Lakes provide ecosystem services such as water resources, tourism, biodiversity, and fishing, and therefore their management represents important societal challenges. Since the early 1960s, significant anthropogenic pressures (human population growth and industrial and agricultural development) have accelerated the degradation of lake ecosystems, leading to eutrophication and subsequent increased sedimentation on fish spawning grounds and decreased dissolved oxygen concentrations. This negatively affects the natural recruitment of whitefish (Coregonus lavaretus), an emblematic species of peri-alpine lakes. Over the years, such processes have resulted in a decline in the whitefish population stock, thereby leading to a drastic drop in catch and causing major economic losses. From the beginning of the 1980s, alongside the restoration of water quality, professional fishers, recreational anglers, state services, and researchers from INRA worked together to develop an applied research program called ‘Pacage Lacustre’ to improve and optimise salmonid stocking. The goal was to counterbalance the low juvenile natural recruitment and maintain whitefish populations. Here, we retrospectively retrace the key stages of this research program and its main impacts on society. Collaborative efforts played a key role in rehabilitating whitefish populations in lakes Geneva and Bourget, particularly when their abundances were the lowest. Therefore, these efforts had a substantial impact on preserving commercial and recreational fishery activities, in addition to favorable societal impacts, highlighting the importance of such collaborative work.