Habitat conservation of paddy field fish communities and the Oriental White Stork Ciconia boyciana using ecological networks from river to paddy

Abstract

To conserve paddy field fish communities and the foraging habitats of Oriental White Storks Ciconia boyciana, a wetland area connecting the Kamatani River to a fallow field biotope (paddy area) was created by means of fishways and a permanent deep water area within the biotope in Toyooka City, central Japan. This ecological network had the following positive effects on paddy field fish species: 1) Gnathopogon elongatus elongatus became more abundant in the upstream habitat following restoration; 2) G. elongatus elongatus and Carassius spp. reproduced for the first time in the biotope after restoration; 3) C. spp. and Misgurnus anguillicaudatus utilized the fishway to swim up to the biotope; 4) current-year juvenile G. elongatus elongatus, C. spp., and M. anguillicaudatus grew in the biotope, and 5) adults and juveniles overwintered in the biotope, and Oryzias sakaizumii especially assembled within the deep water area. After restoration, storks regularly visited the biotope to forage. Additionally, one pair nested near the biotope and fledged five young during the 2016–2017 breeding seasons. The young birds and their parents continued to forage frequently in the biotope. Thus, our results indicate that ecological networks for paddy field fish communities contribute greatly to the foraging and breeding habitats of reintroduced storks.