Abstract: Invasive alien insects that cause severe damage to agricultural crops and are designated by the Plant Protection Act are called special pests. The sterile insect release method (=sterilization method) was started in 1971 to eradicate the special pest melon fly. 100 million sterile fruit flies were sprayed from helicopters every week, and in 1993, melon flies were finally eradicated from Japan. Just before eradication, data were published suggesting the appearance of females (resistant females) that could distinguish sterile males in some areas of Okinawa Island (Hibino and Iwahashi 1989, 1991), but the national and prefectural governments thoroughly sprayed huge amounts of sterile insects in areas where wild insects remained, completely eradicating them. As a result, one question remained: Did females evolve that could distinguish sterile males? Together with my students, I used a beetle Tribolium castaneum, which can be bred in Okayama, and measured the generational changes in female traits in an experimental area where sterile males and normal males were exposed to females, and in a control area where only normal males were exposed to females, by repeatedly breeding for more than 15 generations. In this seminar I would like to report and discuss the results.
We conducted a survey on the spawning migration of wild eels in Shizuoka and Kumamoto!
IFB
We conducted a spawning migration survey using pop-up tags on natural downstream eels in Shizuoka Prefecture on December 2, 2024, and in Kumamoto Prefecture on December 13, 2024.
In Shizuoka Prefecture, we set out by boat from Lake Hamana and released five individuals in an area approximately 700 meters deep.
In the Ariake Sea in Kumamoto Prefecture, we released three individuals in shallow water inside the bay.
This is the first time we have tried to collect data on eels migrating to the open ocean. We saw many dolphins from the boat!
We received cooperation from Ebisen Co., Ltd., the Fishing Shop BLUEJUNKIE, and the Kumamoto Prefectural Fisheries Research Center for this survey.
Thank you very much.
Nagano University Mitsuo Seminar students visited the Institute of Freshwater Biology!
IFB
On Thursday, December 12, 2024, 15 first-year seminar students of Professor Yoshito Mitsuo visited the Institute of Freshwater Biology as part of their seminar activities. The students were briefed about the Institute of Freshwater Biology, its research projects on river ecology and Japanese eel, and its research, education, social contributions, and history. They also toured the wild fish stocks on the premises, as well as the facilities and equipment.
The Chikuma-Shinano Rivers Research Group presented their results at the River Ecology Academic Research Presentation (Tokyo Shoken Hall)
IFB
On November 21, 2024, the Chikuma River and Shinano River Research Group presented their results at the River Ecology Academic Research Presentation at the Tokyo Shoken Hall.
Hiroshi Hakoyama* (IFB, Nagano University) On the importance of habitat continuity for riverine ecosystems and related restoration measures.
Alessandra CERA*, Sakie KODAMA, Leanne FAULKS, Hiroshi HAKOYAMA (IFB, Nagano University) Effects of water flow velocity on metabolic functionality of freshwater epilithic biofilms: a field and laboratory study.
Leanne FAULKS*, Alessandra CERA, Sakie KODAMA, Hiroshi HAKOYAMA (IFB, Nagano University) River fragmentation at the local scale: effects on biodiversity.
Takato IDO, Mei YOSHIMURA, *Masashi TOYOTA (Faculty of Engineering, Shinshu University) River channel evolution in the middle reaches of the Chikuma River as seen from cross-sectional survey data and aerial photographs
Professor Hakoyama's Comments Published in Nihon Keizai Shimbun Article
IFB
On November 20, 2024, Professor Hiroshi Hakoyama’s comments were published in the Nihon Keizai Shimbun print and online articles “Minister of Land, Infrastructure, Transport and Tourism encourages setting numerical targets for river environment conservation, such as tidal flat area, visualization of ecosystem recovery” and “Ministry of Land, Infrastructure, Transport and Tourism sets new targets for river environment and ecosystem maintenance”.
The 8th IFB Seminar took place in the conference room of the Institute of Freshwater Biology.
Title: Fish that adapt their buoyancy to the environment
Lecturer: Yoshida Makoto
Affiliation: Special Researcher, Atmosphere and Ocean Research Institute, University of Tokyo
Abstract: Many fishes that swim underwater support their weight by obtaining buoyancy from the air in their swim bladders, reducing energy expenditure during swimming. On the other hand, in situations where sufficient buoyancy is not available, they use gliding swimming, which involves diving without swinging the caudal fin, to reduce the cost of locomotion. I will report on biological research on freshwater catfish and two strains of carp from Lake Biwa, taking into account the quality associated with maintaining buoyancy. I inferred the buoyancy state of Carrera during swimming from the behavioral records of the fish in the wild. Through these studies focusing on the trends in buoyancy regulation according to habitat, we will consider the behavioral adaptation of the three fish species from the perspective of buoyancy.
On October 24, 2024, a meeting of the Glass Eel Research Group of the International Resource Project Eel Unit, commissioned by the Fisheries Agency, was held at the Institute of Freshwater Biology. The Glass Eel Research Group is conducting long-term studies of glass eel migration in several regions through direct, non-fishing surveys. The meeting was also streamed online and was attended by more than 20 people from the Fisheries Agency and the Eel Unit. Lively discussions followed the agenda below.
Meeting Agenda
Date: October 24th
Time: 13:30-15:40
Location: Institute of Freshwater Biology Conference Room, 1088 Komaki, Ueda City, TEL 0268-22-0594
Opening Ceremony
Survey of glass eels in Miyazaki, Teru Takahashi/Shuichi Hayashida (online) (13:30-13:50)
Glass eel survey in Wakayama, Yoshitsugu Kaji (13:50-14:10)
Glass eel survey in Kagoshima, Takashi Shiosaki (14:10-14:30)
10 minute break (14:30-14:40)
Glass eel survey in Fukuoka, Noritaka Mochioka (14:40-15:00)
Glass eel survey in Chiba, Yasuhiko Mabuchi (15:00-15:20)
General discussion (15:20-15:40)
Conclusion
10-minute break (15:40-15:50)
Data Analysis Session
Time: 15:50-18:00
Time series data analysis 2 by Hakoyama Hiroshi (15:50-16:10)
Discussion of Analysis of Survey Data from Each JV (16:10-18:00, with breaks)
The 2024 River Ecology Academic Research Group Chikuma River Field Trip was held!
IFB
A field trip to the research area of the Chikuma River and Shinano River Research Group (represented by Professor Hiroshi Hakoyama), which is part of the River Ecology Academic Research Group, was held on October 17 and 18. More than 50 people participated in the research, including members of the parent committee of the River Ecology Academic Research Group, members of the research group and related departments of the Ministry of Land, Infrastructure, Transport and Tourism, and the Riverfront Research Institute as the secretariat. This project research, funded by the River Ecology Research Fund of the Ministry of Land, Infrastructure, Transport and Tourism, focuses on the effects of river fragmentation on fish populations and communities. We are studying the fragmentation of the Shinano River by large dams and other structures throughout the river, and the fragmentation of the main river, tributaries, and irrigation canals by relatively small weirs. During this tour, we compared the Miyanaka Water Intake Dam and the small weirs at the Institute of Freshwater Biology, and also visited construction sites (Kamiimai Reservoir, etc.) for river basin flood control projects being implemented by the Chikuma River Office (photo). The primary goal of the Chikuma River and Shinano River Research Group is academic research, and the results will be useful for the river basin flood control projects conducted by the Ministry of Land, Infrastructure, Transport and Tourism.
