Abstract
The Japanese eel (Anguilla japonica) population has experienced significant declines across East Asia. The canal network called Horiwari in Yanagawa City, Fukuoka Prefecture, Japan is no exception. The deployment of sluice gates between Horiwari and adjacent rivers may have prevented eels from entering the canal, which has likely reduced the eel population in the area. A local high school and nonprofit organization have been releasing tagged juvenile eels into the canal to aid in the recovery of the species. However, there is currently limited knowledge regarding the effectiveness of these efforts in repopulating the canal with both wild and released eels. We used an electro-fishing unit to collect eels during five surveys conducted in October 2021, February, March, and November 2022, and February 2023. A total of 47 eels were collected, ranging from 122 to 623 mm in total length. Two silver phase eels were collected in November 2022, while the remaining 45 yellow phase eels were at all surveys. Our observations indicated that eels of varying lengths utilized mud and sand habitats, with larger eels (> 400 mm in total length) primarily found in boulder or stonewall habitats rather than pebble or cobble areas. These findings suggest that Horiwari offers a suitable habitat for Japanese eels to inhabit and to grow and provide important insights into the effectiveness of current recovery efforts for this endangered species in the region.
https://ror.org/02kpeqv85 
