4th Eel Scientific Meeting Held in Hamamatsu, Japan
IFB
The 4th Eel Scientific Meeting was held in Hamamatsu, Japan, on June 16-17, 2025. This international meeting, hosted by Japan, brought together researchers and government officials from Japan, China, South Korea, and Chinese Taipei to discuss the sustainable management of eel resources. Professor Hiroshi Hakoyama and Researcher Huỳnh Quang Thiện from the Institute of Freshwater Biology (IFB) presented three research papers during the meeting, along with other contributors from the participating countries and regions.
Additionally, Dr. Shannan Crow from the National Institute of Water and Atmospheric Research (NIWA) in New Zealand, as an invited speaker, delivered a special talk on “Eel Recruitment Patterns at Hydroelectric Stations Across New Zealand”.
The meeting aimed to provide scientific advice on the sustainable use of eels in the context of the “Informal Consultation on International Eel Resource Conservation and Management” (Informal Consultation).
Researchers Takeru Kodama and Huỳnh Quang Thiện participated in Shizuoka Prefecture's yellow eel survey at Lake Hamana.
IFB
On Friday, June 6, 2025, researchers Takeru Kodama and Huỳnh Quang Thiện from the Institute of Freshwater Biology participated in a yellow eel collection survey at the mouth of the Miyakoda River in Hamamatsu City, Shizuoka Prefecture. The survey was carried out jointly with researchers from the Lake Hamana Branch of the Shizuoka Prefectural Fisheries and Marine Technology Research Institute.
The Lake Hamana Branch regularly conducts these surveys to collect morphological and ecological data, such as body size and sex ratios of wild yellow eel populations, as well as genetic information, including DNA and RNA samples. At the Institute of Freshwater Biology, we will analyze this data to develop a practical method for determining the sex of eels based on RNA analysis. The foundation of this method was developed in recent years by Hsu et al. (2023).
The first year seminar of Professor Kazuaki Takahashi from the Faculty of Environmental Tourism visits us and learns about the efforts of the Institute of Freshwater Biology and the local nature!
IFB
On Thursday, June 5, 2025, 16 first-year students from the Faculty of Environmental Tourism visited the Institute of Freshwater Biology as part of Professor Kazuaki Takahashi’s first-year seminar. They learned about local nature and issues, the Institute’s efforts, and research on the fragmentation of the Chikuma River. The students toured the facility and learned about a universal projector that magnifies fish scales and determines their age from tree rings, as seen in the photo. The Institute of Freshwater Biology will continue to contribute to educational activities like this one.
Water quality and biological surveys were conducted in the middle of the Chikuma River, from Saku City to Ueda City
IFB
On May 21, 2025, water quality and aquatic microbial flora activity surveys were conducted in the Chikuma River. The eight sampling points included the Imai Weir, the Nishiura Dam, and the Yoda River. The aim of this survey is to understand the impact of the dams on water quality and biota. We will also study the fish fauna using eDNA. Takeru Kodama and Mitsuki Ohara will conduct monthly field surveys. Water quality tests will be conducted in collaboration with the Nagano Prefecture Ueda Waterworks Management Office.
These surveys are part of the Ministry of Land, Infrastructure, Transport and Tourism’s River Erosion Control Technology Research and Development Regional Issues Field (River Ecology) General Research project, “The Importance of Habitat Continuity in Rivers: Impact Assessment and Conservation Measures on River Ecosystems.” This large-scale project is being promoted by a research group led by the Institute of Freshwater Biology, Nagano University, Shinshu University, and the Nagano Prefectural Fisheries Experimental Station.
The Chikuma River and Shinano River Research Group kickoff meeting was held
IFB
On May 19, 2025, the group held its kickoff meeting online. We discussed past research, 2025 research plans, and the five-year summary of research for this project. Attendees included the Institute of Freshwater Biology, Nagano University, the Nagano Prefectural Fisheries Experimental Station, and research contributors from the Shinshu University Faculty of Engineering, as well as the Chikuma River Office and the Shinano River Office.
The Chikuma River and Shinano River Research Group is a Ministry of Land, Infrastructure, Transport and Tourism research group led by Professor Hiroshi Hakoyama. The group’s research focuses on the importance of habitat continuity in rivers and aims to clarify the impact of disturbances and the presence of river constructions on habitat continuity, as well as the health and sustainability of populations and communities.
The Eel Unit's Glass Eel Research Group held a kickoff meeting
IFB
On May 9, 2025, the group held an online meeting to start working. New staff members were introduced, annual plans were confirmed, and the fourth Eel Scientists’ Meeting was discussed.
Through the Fisheries Resource Survey and Evaluation Promotion Project’s commissioned and subsidized project in 2025, the Eel Unit is conducting research that contributes to the management of Japanese eel and other species resources.
Research at the Institute of Freshwater Biology was featured in the Shinshu Minpo newspaper on April 19
IFB
An introduction to a research paper published in Aquatic Toxicology on the effects of neonicotinoid pesticides on microbial communities on the rock surfaces of river beds was published in the Shinshu Minpo newspaper on April 19.
This research was supported by a research grant from the Ministry of Land, Infrastructure, Transport and Tourism, River Erosion Control Technology Research and Development Open Call, Regional Issues Field (River Ecology), “The Importance of Habitat Continuity in Rivers - Impact Assessment and Conservation Measures for River Ecosystems” (Representative: Hiroshi Hakoyama).
Journal: Aquatic Toxicology
Title: Community-level effects of a neonicotinoid pesticide on the metabolism of freshwater microorganisms
Authors: Alessandra CERA, Sakie KODAMA, Leanne K. FAULKS, and Hiroshi HAKOYAMA
DOI：https://doi.org/10.1016/j.aquatox.2025.107311
[Nagano University Press Release]: Effects of neonicotinoid pesticides on river microbial communities
IFB
2025-04-01 We are pleased to announce that a new scientific article authored by researchers at the Institute of Freshwater Biology has recently been published in Aquatic Toxicology, a leading international journal in its field https://www.sciencedirect.com/journal/aquatic-toxicology.
Key points of the study
The effect of the pesticide dinotefuran on freshwater biofilms (microbial communities) was measured for the first time using the EcoPlates method
Contrary to expectations, exposure to pesticides increased the metabolic activity of freshwater biofilms (microbial communities) on average
Among these, the metabolic activity of putrescine increased most significantly
Research Summary
The study advances knowledge of the effects of a common neonicotinoid pesticide, dinotefuran, on freshwater organisms using the EcoPlate method for the first time. In particular, the microorganisms living on the rocks of the river beds were studied to observe the disturbance induced by the presence of dinotefuran. We studied changes in metabolism as an indicator of stress in microorganisms. The results show that dinotefuran increased the mean catabolic activity of the freshwater biofilm. We also found that the catabolism of putrescine increased significantly after exposure to dinotefuran. Overall, we suggest that dinotefuran, at the concentration tested, has stressed the microorganisms. However, further research should continue to elucidate the complex response.
This research is part of a larger project investigating the effects of anthropogenic disturbances on river health, funded by the Japanese Ministry of Land, Transport and Tourism.
Prof. Leanne Faulks of the Institute of Freshwater Biology presented at the 72nd meeting of the Ecological Society of Japan.
IFB
The Ecological Society of Japan held its 72nd conference in Sapporo from March 15-18, 2025. Leanne Faulks from the Institute of Freshwater Biology, Nagano University travelled to Sapporo to participate in a symposium titled Connectivity in river ecology: from genes to meta-ecosystem dynamics. Leanne presented the results of a research project that examined the influence of small weirs on fish biodiversity in streams around Ueda City. This study indicated that small weirs reduce fish movement and result in reduced levels of species and genetic diversity. Other speakers in the symposium also highlighted the importance of connectivity in watersheds for freshwater ecosystem function and biodiversity, including forest-stream linkages and freshwater-marine linkages.
We conducted a satellite tagging survey of Japanese eels on Hachijojima Island!
IFB
On February 20-23, 2025, we conducted a spawning migration survey using satellite-based pop-up tags on farmed eels on Hachijojima. This is a new initiative in which farmed Japanese eels are transported to Hachijojima and released in coastal areas. Several dozen wild eels have been released along the coast of Japan so far. However, there is still room for improvement in the satellite tags, and only a limited number of them have been able to cross the Kuroshio Current, a strong ocean current, and travel south. It is known that wild eels also live on Hachijojima, about 300 km south of Tokyo Bay. Since the Kuroshio Current is often farther north than Hachijojima, it is thought that if the migration starts from Hachijojima, we will be more likely to observe the migration behavior to spawning grounds far off the coast of Guam. This time we released two eels at Hachijojima.
This research is conducted as a supplementary research project of the International Eel Resources Unit of the Fisheries Agency, led by the Institute of Freshwater Biology of Nagano University, in cooperation with the Atmosphere and Ocean Research Institute of the University of Tokyo, Kyushu University, Shinshu University, Miyazaki Prefecture, Kumamoto Prefecture, and the Fisheries Research Institute. We would like to thank the Hachijo Office of the Island Agriculture, Forestry and Fisheries Research Center for their cooperation in this survey.
