Researcher basic information

• Ph.D.(Environmental Science), Hokkaido University, Mar. 2024

• https://researchmap.jp/ryotahasegawa?lang=en

• https://orcid.org/0000-0002-3563-7031
• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=202101010141480420
• https://ryotahase344922.wixsite.com/ryotahasegawa-salmin

• 51038857

• https://orcid.org/0000-0002-3563-7031

• 202101010141480420

• 魚類
• 寄生性カイアシ類
• サケ科魚類
• 水産学
• 寄生虫
• 生態学

• Life Science, Aquatic bioproduction science
• Environmental Science/Agriculture Science, Conservation of biological resources
• Life Science, Ecology and environment

Research activity information

• Mar. 2022, ESJ69, Best English Presentation Award
  Do impacts and infection levels of parasite change across seasons? A test in stream salmonid and parasitic copepod system
  Ryota Hasegawa;Itsuro Koizumi
• Oct. 2021, 日本寄生虫学会・日本衛生動物北日本支部, 日本寄生虫学会・日本衛生動物学会第67回北日本支部合同大会 若手奨励賞
  口に寄生された魚は釣られにくいか：イワナに寄生するカイアシ類ナガクビムシの影響評価
  長谷川稜太, 小泉逸郎
• Jul. 2021, 日本学生支援機構, 特に優れた業績による返還免除（全額免除）
• Mar. 2021, 日本生態学会, 最優秀ポスター発表賞（動物個体群）
  寄生虫感染個体の低いボディコンディション：原因か結果か、両方か
  長谷川稜太;大槻泰彦;植村洋亮;古澤千春;中正大;小泉逸郎
• Feb. 2021, 北海道大学環境科学院 生物圏科学専攻, 令和2年度 北海道大学環境科学院生物圏科学専攻 修士論文発表会 修士論文優秀発表賞
  Factors affecting the distribution of parasitic copepods Salmincola spp. and their impacts on host salmonids
• Nov. 2020, 個体群生態学会, 最優秀ポスター発表賞
  寄生虫の感染は新たな寄生虫の感染を引き起こすか：イワナとサルミンコーラを対象とした標識採捕による検証 個体群生態学会
  長谷川稜太, 大槻泰彦, 古澤千春, 植村洋亮, 中正大, 小泉逸郎
• Nov. 2019, 2019年度（令和元年度）日本生態学会北海道地区大会, 若手研究奨励賞
  イワナに寄生するカイアシ類における感染率の生息地間変異と宿主への影響
  長谷川稜太, 小泉逸郎

• Does bigger mean sicker? A systematic review and meta‐analysis of the intraspecific relationship between host body size and parasite infection across vertebrate taxa
  Ryota Hasegawa; Daniela de Angeli Dutra; Bronwen Presswell; Jerusha Bennett; Cameron McDougall; Katherine E. Buschang; Xuhong Chai; Robert Poulin
  Oikos, e11823, 07 Aug. 2026, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Do Parasite Effects on Fish Body Condition Depend on Host Size and External Temperature? A Meta‐Analytic Approach
  Ryota Hasegawa; Callum B. Walter; Robert Poulin
  Journal of Zoology, 05 Aug. 2026, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Mechanisms of local coexistence in juvenile congeneric salmonids in small tributaries with different thermal regimes
  Yohsuke Uemura; Yasuhiko Otsuki; Ryota Hasegawa; Masahiro Naka; Itsuro Koizumi
  Oecologia, Jun. 2026, [Peer-reviewed]
  Scientific journal
• Validating a Past Local Extinction Model Using Site‐Level Disappearances in a Cold‐Adapted Salmonid Under Global Warming
  Yohsuke Uemura; Ryota Hasegawa; Yoshinori Taniguchi; Yoichi Kawaguchi; Koh Hasegawa; Yuma Takeuchi; Natsuki Hara; Yasuhiko Otsuki; Kiyoshi Kasugai; Takeaki Oiso; Kazutaka Shimoda; Hirokazu Urabe; Itsuro Koizumi
  Freshwater Biology, May 2026, [Peer-reviewed]
  Scientific journal
• Scientists' Warning on the Rapid Evolution of Parasites in the Anthropocene
  Robert Poulin; Jerusha Bennett; Isabel Blasco‐Costa; Daniela de Angeli Dutra; Jean‐François Doherty; Eddy Dowle; Antoine Filion; Brian L. Fredensborg; Ryota Hasegawa; Kristin K. Herrmann; Devon B. Keeney; Anson V. Koehler; Janet Koprivnikar; Clément Lagrue; Henry S. Lane; Tommy L. F. Leung; Chen‐Hua Li; Colin D. MacLeod; Kim N. Mouritsen; Chris N. Niebuhr; Katie O'Dwyer; Eunji Park; Rachel A. Paterson; Bronwen Presswell; Haseeb S. Randhawa; Brandon Ruehle; Amandine Sabadel; Priscila M. Salloum; David W. Thieltges; Frédéric Thomas; Christian Selbach
  Evolutionary Applications, 19, 4, Wiley, 28 Apr. 2026, [Peer-reviewed]
  Scientific journal, ABSTRACT
  
  Human activities are changing the natural world at an accelerating pace, and as a consequence exerting novel and often strong selection pressures on living organisms. For species with traits conferring huge inherent evolutionary potential, like parasites, the outcome may be rapid adaptive responses spanning multiple phenotypic traits. The rise of drug resistance in parasites of domesticated animals is well documented; however, rapid changes in other key parasite traits may go unnoticed. In this contribution to the Scientists' Warning series, we argue that parasites are capable of evolving quickly to meet the new pressures of the Anthropocene. After summarizing evidence demonstrating their ability to evolve quickly and the magnitude of the anthropogenic selection pressures they now face, we discuss the basic types of adaptive responses we might expect. Next, we propose methods to track rapid parasite evolution in real time, as well as possible approaches to either slow it down or mitigate its impact on animal production systems. Our aim is to raise awareness of this concerning but underappreciated phenomenon and appeal for greater research into rapid parasite evolution in the Anthropocene and its consequences.
• Recent Emergence and Distributional Expansion of the Parasitic Copepod Lernaeenicus cf. ramosus in Japanese Waters Revealed by Web Image Surveys
  Ryota Hasegawa
  Marine Ecology, Mar. 2026, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Colorful parasites: an overlooked frontier in animal coloration research
  Ryota Hasegawa; Robert Poulin
  Trends in Parasitology, Mar. 2026, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Cause or consequence? Exploring authors' interpretations of correlations between fish body condition and parasite infection
  Ryota Hasegawa; Robert Poulin
  Journal of Fish Biology, Aug. 2025, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Testing for Consistency in Co-occurrence Patterns Among Bacterial Taxa Across the Microbiomes of Four Different Trematode Parasites
  Ryota Hasegawa; Robert Poulin; Priscila M. Salloum
  Microbial Ecology, 17 May 2025, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Effect of parasite infections on fish body condition: a systematic review and meta-analysis.
  Ryota Hasegawa; Robert Poulin
  International Journal for Parasitology, 07 Apr. 2025, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Using host body condition indices (BCIs) based on the relationship between host body mass and length is a general and pervasive approach to assess the negative effects of parasites on host health. Although many researchers, especially fish biologists and fisheries managers, commonly utilize BCIs, the overall general patterns among BCI - infection relationships remain unclear. Here, we first systematically reviewed 985 fish BCI - infection relationships from 216 publications and investigated the factors affecting the strength and directionality of effects in BCI - infection relationships. We specifically predicted that the BCI measure used, parasite taxonomic group, and the infection measure used would influence the observed effect size and directionality of BCI - infection relationships. We found that most studies were heavily biased towards specific BCI measures such as Fulton's BCI and Relative BCI. Furthermore, studies using Fulton's BCI were more likely to report significant results compared with those using other BCI measures, suggesting that index choice could lead to an overestimation of the negative effects of parasites. Our meta-regressions uncovered that the use of parasite intensity as an infection measure and studies based on experimental rather than natural infections were more likely to report significant negative effects, however there were no differences among parasite taxonomic groups. Surprisingly, many studies, especially field studies, did not report significant negative correlations between BCI and infection, contrary to widespread expectations among researchers that parasites would negatively affect fish health. We discuss potential mechanisms underlying these results. Finally, we make several recommendations for the use of BCI - infection relationships in future studies.
• Positive feedback between parasite infection and poor host body condition reduces host survival in the wild
  Ryota Hasegawa; Yasuhiko Otsuki; Yohsuke Uemura; Chiharu Furusawa; Masahiro Naka; Yoichiro Kanno; Itsuro Koizumi
  Functional Ecology, Mar. 2025, [Lead author, Corresponding author]
  Scientific journal
• A new locality record of the ectoparasitic copepod <i>Salmincola californiensis</i> in Japan: A potential glacial relict population?
  Ryota Hasegawa; Yukihito Sugimoto; Itsuro Koizumi
  Crustacean Research, 54, 1, 7, Carcinological Society of Japan, 18 Feb. 2025, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Highly Threatened Status for the Relict Populations of Ectoparasitic Copepod Salmincola californiensis in Japan
  Ryota Hasegawa; Yohsuke Uemura; Yasunori Yamashita; Makoto Inoshita; Itsuro Koizumi
  Aquatic Conservation: Marine and Freshwater Ecosystems, Feb. 2025, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Do Mouth‐Infecting Parasites Alter the Foraging Ecology of Host Fish? A Test With the Parasitic Copepod Salmincola markewitschi and White‐Spotted Charr Salvelinus leucomaenis
  Ryota Hasegawa; Itsuro Koizumi
  Freshwater Biology, Jan. 2025, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Mouth-attaching copepod Salmincola markewitschi reduces the body condition and growth of juvenile salmonids, Salvelinus leucomaenis, by decreasing host feeding activity: evidence from parasite removal experiment
  Leo Murakami; Ryota Hasegawa; Nozomi Aruga; Nobuhiro Sato; Shingo Nakamura; Hiroshi Kajihara; Itsuro Koizumi
  Canadian Journal of Zoology, 01 Jan. 2025, [Corresponding author]
  Scientific journal
• Host Specificity of the Parasitic Copepod <i>Salmincola markewitschi </i>in an Aquarium
  Ryota Hasegawa; Leo Murakami; Nozomi Aruga; Nobuhiro Sato; Shingo Nakamura; Itsuro Koizumi
  Fish Pathology, 59, 4, 139, 142, The Japanese Society of Fish Pathology, 15 Dec. 2024, [Peer-reviewed], [Lead author, Corresponding author]
  Japanese, Scientific journal
• Consistent Negative Correlations between Parasite Infection and Host Body Condition Across Seasons Suggest Potential Harmful Impacts of Salmincola markewitschi on Wild White-Spotted Charr, Salvelinus leucomaenis
  Ryota Hasegawa; Itsuro Koizumi
  Zoological Science, 41, 2, 192, 200, 12 Jan. 2024, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Parasites either reduce or increase host vulnerability to fishing: a case study of a parasitic copepod and its salmonid host
  Ryota Hasegawa; Itsuro Koizumi
  The Science of Nature, 110, 10, Apr. 2023, [Peer-reviewed], [Lead author, Corresponding author]
  Scientific journal
• Salmincola markewitschi or S. carpionis (Copepoda: Lernaeopodidae)? A requirement for taxonomic revision due to their high morphological variations.
  Ryota Hasegawa; Hirotaka Katahira; Itsuro Koizumi
  Folia parasitologica, 69, 025, 03 Nov. 2022, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, Salmincola markewitschi Shedko et Shedko, 2002 (Copepoda: Lernaeopodidae) is an ectoparasitic copepod mainly infecting the buccal cavities of white-spotted charr Salvelinus leucomaenis (Pallas) (Salmonidae). This species has only been recorded from Northeast Asia, where a morphologically similar congener Salmincola carpionis (Krøyer, 1837) is also distributed, using the same host species. These copepods are hard to distinguish from each other because of their similarities. We thus examined the newly collected specimens morphologically and genetically from five populations of white-spotted charr in Japan. Most of the specimens were morphologically consistent with S. markewitschi but showed great variations in the numbers of spines on the exopods of the antennae, shape of the maxilliped myxal palps, and the bulla diameter. Consequently, some specimens shared characteristics with S. carpionis. In addition to the mophological continuities, genetic analyses of 28S rDNA and COI mitochondrial DNA confirmed that all specimens belong to a single species. Further taxonomic revisions are required to draw conclusions of whether S. markewitschi is a valid species different from S. carpionis, by collecting samples from across their wide distributional ranges, such as Europe, North America, and Northeast Asia. A key to identification of species of Salmincola Wilson, 1915 occurring in Japan is also provided.
• Rediscovery of Lernaeenicus ramosus Kirtisinghe, 1956 (Copepoda: Pennellidae) parasitizing the type host, comet grouper Epinephelus morrhua (Perciformes: Serranidae) from the Japanese coast, with a note on its underdeveloped head
  Ryota Hasegawa; Masato Nitta
  Biogeography, 24, 25, 31, Sep. 2022, [Peer-reviewed], [Lead author, Corresponding author]
• Potential negative effects and heterogeneous distribution of a parasitic copepod Salmincola edwardsii (Copepoda: Lernaeopodidae) on Southern Asian Dolly Varden Salvelinus curilus in Hokkaido, Japan.
  Ryota Hasegawa; Christopher G Ayer; Yoshiyuki Umatani; Kazuki Miura; Miyo Ukumura; Hirotaka Katahira; Itsuro Koizumi
  Parasitology International, 87, 102529, 09 Dec. 2021, [Peer-reviewed], [Lead author, Corresponding author], [International Magazine]
  English, Scientific journal, The genus Salmincola is an ectoparasitic copepod group commonly infesting the branchial and buccal cavities of salmonids. While negative impacts on hatchery fishes have been reported, their impacts on wild fish populations and distribution patterns are critically understudied. In the Shiretoko Peninsula, Hokkaido, Japan, we found parasites belonging to this genus on the branchial cavity of a stream salmonid, Southern Asian Dolly Varden Salvelinus curilus. All parasites recovered were identified as Salmincola edwardsii based on morphological characteristics and partial 28S rDNA sequences. Prevalence was highly heterogeneous even among neighboring streams (0-54.8%, < 10 km) with the mean intensity among streams being generally low (2.19 parasites/infeted fish). Despite the low intensity, quantile regression analysis showed negative trends between parasite intensity and host condition, suggesting that the infestation of S. edwardsii has a potential negative impact on the host salmonid. In addition, a single copepod was found from an anadromous fish, which could indicate some salinity tolerance of the copepods. It is important to evaluate the effects of Salmincola spp. on host species and determine the limiting factors on the parasite's distribution for proper management.
• Relative importance of host‐dependent versus physical environmental characteristics affecting the distribution of an ectoparasitic copepod infecting the mouth cavity of stream salmonid
  Ryota Hasegawa; Itsuro Koizumi
  Ecological Research, 36, 1015, 1027, 12 Sep. 2021, [Peer-reviewed], [Lead author, Corresponding author]
  English, Scientific journal
• Personality differences in white-spotted char fry evident between habitats
  長谷川稜太; 長谷川稜太; 山田寛之; 石原千晶; 和田哲
  魚類学雑誌, 67, 1, 11, 24, 2020, [Peer-reviewed], [Lead author, Corresponding author]

• Disentangling the causality between parasite infections and poor host conditions in the wild population
  Ryota Hasegawa; Yasuhiko Otsuki; Yohsuke Uemura; Chiharu Furusawa; Masahiro Naka; Itsuro Koizumi, 18 Jan. 2023
  

  Although parasites reduce host health, parasite infections also occur asa consequence of compromised host health. Both causalities could inducepositive feedback, in which infected hosts with poor body conditions maysuffer further infection, but it has rarely been demonstrated in thewild, possibly due to methodological difficulties. We used amark-recapture survey combined with structural equation modelling (SEM)to examine whether both causalities and positive feedback occurred instream salmonid and parasitic copepod systems. We found that parasiticcopepods reduced host conditions and hosts with poor conditions werelikely to be infected, suggesting that positive feedback can occur inthe wild. Importantly, heavily infected hosts with poor body conditionsshowed lower apparent survival rates. Our findings provide robustevidence showing host condition–parasite infection dynamics, offeringnovel insights into how positive feedback could strongly undermine thewild host population via reduction of host survival.

  , Authorea, Inc.
• Disentangling the causal relationship between parasite infection and low host condition
  長谷川稜太; 大槻泰彦; 植村洋亮; 古澤千春; 中正大; 小泉逸郎, 日本生態学会大会講演要旨(Web), 68th, 2021
• Do parasite infections cause new parasite infections?: a mark-recapture approach focusing on white-spotted charr and their parasitic copepods Salmincola carpionis
  長谷川稜太; 大槻泰彦; 古澤千春; 植村洋亮; 中正大; 小泉逸郎, 個体群生態学会大会プログラム・講演要旨集(Web), 36th, 2020

• 海外留学は若手研究者をいかに自立させるか
  長谷川稜太
  令和8年度日本水産学会春季大会 水産学若手の会主催シンポジウム: 国際舞台で活躍する研究者たち：海外で学び、研究を楽しむために, 26 Mar. 2026
  [Invited]
• 温暖化にともなうオショロコマの局所絶滅：過去の予測モデルの評価
  植村洋亮; 長谷川稜太; 谷口義則; 河口洋一; 長谷川功; 武内優真; 原成月; 大槻泰彦; 春日井潔; 大磯毅晃; 下田和孝; 卜部浩一; 小泉逸郎
  第59回日本魚類学会年会, 23 Nov. 2025
• How to use “Notion” in research activities
  Zoo Lunch; a seminar for postgraduate; students of Department of Zoology
  Jul. 2025
• Positive feedback between parasite infection and poor host body condition reduces host survival: a case study of parasitic copepod and their host freshwater salmonids
  Ryota Hasegawa
  2025 Joint Conference of the Asian Society of Ichthyologists Annual Meeting and the 12th Indo-Pacific Fish Conference, 12 Jun. 2025, English, Oral presentation
  09 Jun. 2025 - 13 Jun. 2025
• 温暖化によるオショロコマ個体群絶滅予測モデルの評価
  植村洋亮; 長谷川稜太; 谷口義則; 河口洋一; 武内優真; 原成月; 大槻泰彦; 大磯毅晃; 下田和孝; 卜部浩一; 長谷川功; 小泉逸郎
  第45回魚類系統研究会, 07 Dec. 2024
• Web-posted images revealed the temporal dynamics of the marine parasitic copepods Lernaeenicus ramosus
  Ryota Hasegawa
  Department of Zoology Postgraduate Colloquium, 30 Oct. 2024, English, Poster presentation
  30 Oct. 2024 - 30 Oct. 2024
• Ecology of parasitic copepods infecting freshwater salmonids: effects on host health and geographic distribution
  Ryota Hasegawa
  Departmental Seminar series, Department of Zoology, University of Otago, 13 Sep. 2024, English, Public discourse
• Effect of parasite infections on fish body condition: a systematic review
  Ryota Hasegawa; Robert Poulin
  Parasites in the Pacific 2024 Conference, 28 Aug. 2024, English, Oral presentation
  26 Aug. 2024 - 29 Aug. 2024
• 温暖化による河川性サケ科魚類の局所絶滅の検証：30年前との分布比較
  植村洋亮; 長谷川稜太; 武内優真; 長谷川功; 原成月; 大槻泰彦; 小泉逸郎
  日本生態学会第71回大会, 20 Mar. 2024, Poster presentation
  16 Mar. 2024 - 21 Mar. 2024
• Evaluating the temperature-dependent effects of parasites on cold-water salmonids
  長谷川稜太; 植村洋亮; 三浦一輝; 小泉逸郎
  日本生態学会第71回大会, 19 Mar. 2024, Poster presentation
  16 Mar. 2024 - 21 Mar. 2024
• 過去30年の温暖化にともないオショロコマの分布は実際に減少したのか？
  植村洋亮; 長谷川稜太; 武内優真; 長谷川功; 原成月; 大槻泰彦; 小泉逸郎
  第44回魚類系統研究会, 08 Dec. 2023
• 日本から絶滅しつつある寄生虫、ヤマメナガクビムシ
  長谷川稜太; 植村洋亮; 山下耕憲; 井下眞; 小泉逸郎
  第44回魚類系統研究会, 08 Dec. 2023
• Coinfection patterns of three ectoparasites on congeneric stream salmonids
  Ryota Hasegawa; Yohsuke Uemura Kazuki Miura; Itsuro Koizumi
  第39回個体群生態学会大会, 28 Oct. 2023, English, Poster presentation
  27 Oct. 2023 - 29 Oct. 2023
• Mechanisms of spatial segregation under highly asymmetric competition in juvenile charr: a field experiment
  Yohsuke Uemura; Yasuhiko Otsuki; Ryota Hasegawa; Masahiro Naka; Itsuro Koizumi
  The 10th International Charr Symposium, 01 Jun. 2023, English, Oral presentation
• Coinfection patterns of three ectoparasites on congeneric stream salmonids and its impacts on host fishes
  Ryota Hasegawa; Yohsuke Uemura; Kazuki Miura; Itsuro Koizumi
  The 10th International Charr Symposium, 01 Jun. 2023, English, Oral presentation
• Mechanisms of spatial segregation under highly asymmetric competition in juvenile salmonids: a field experiment
  Yohsuke Uemura; Yasuhiko Otsuki; Ryota Hasegawa; Masahiro Naka; Itsuro Koizumi
  The 69th Annual Meeting of the Ecological Society of Japan, 18 Mar. 2023
• サケ科魚類に寄生する寄生虫3種の共感染パターンの解明：宿主への影響と地理的分布
  長谷川稜太; 植村洋亮; 三浦一輝; 小泉逸郎
  第70回日本生態学会大会, 18 Mar. 2023
• Parapatric distribution allowed by temperature-dependent competition: a field assessment in two congeneric fishes
  Yohsuke Uemura; Yasuhiko Otsuki; Ryota Hasegawa; Itsuro Koizumi
  The 13th International Congress of Ecology (INTECOL 2022), 31 Aug. 2022
• Positive feedback of parasite infection and reduced host condition: a test by mark-recapture of stream salmonid and parasitic copepod
  Ryota Hasegawa; Yasuhiko Otsuki; Yohsuke Uemura; Chiharu Furusawa; Masahiro Naka; Itsuro Koizumi
  The 15th International Congress of Parasitology (ICOPA 2022), 24 Aug. 2022
  21 Aug. 2022 - 26 Aug. 2022
• ヤマメナガクビムシ属カイアシ類 Salmincola spp. の野外における生態
  長谷川稜太
  第91回日本寄生虫学会大会（第36回生態学・疫学談話会）, 27 May 2022
  [Invited]
• Do impacts and infection levels of parasite change across seasons? A test in stream salmonid and parasitic copepod system
  Ryota Hasegawa; Itsuro Koizumi
  The 69th Annual Meeting of the Ecological Society of Japan, 15 Mar. 2022, English, Oral presentation
  14 Mar. 2022 - 19 Mar. 2022
• 個体群密度や肥満度は生息地の質の指標になるのか?河川性サケ科魚類での検証
  植村洋亮; 大槻泰彦; 長谷川稜太; 中正大; 小泉逸郎
  第69回日本生態学会大会, 15 Mar. 2022
• 寄生虫感染個体の低いボディコンディション：原因か結果か、両方か
  長谷川稜太
  統計数理研究所・共同利用研究集会「生態データ統計モデルの包括的推進：個体群・群集・行動ー生物統計と数理生物：似ているようで異なる生物へのアプローチ」, 07 Jan. 2022
  07 Jan. 2022 - 08 Jan. 2022
• 口に寄生された魚は釣られにくいか: イワナに寄生するサルミンコーラの影響評価
  長谷川稜太; 小泉逸郎
  第42回魚類系統研究会, Dec. 2021
  Dec. 2021
• 口に寄生された魚は釣られにくいか：イワナに寄生するカイアシ類ナガクビムシの影響評価
  長谷川稜太; 小泉逸郎
  日本寄生虫学会・日本衛生動物学会第67回北日本支部合同大会
  02 Oct. 2021
• イワナ類の生息環境評価：個体群密度と個体コンディションに着目した検証
  植村洋亮; 大槻泰彦; 長谷川稜太; 小泉逸郎
  2021年度日本魚類学会年会
  18 Sep. 2021 - 20 Sep. 2021
• 口に寄生されたイワナは釣られにくいか：寄生性カイアシ類の影響評価
  長谷川稜太; 小泉逸郎
  2021年度日本魚類学会年会
  18 Sep. 2021 - 20 Sep. 2021
• イワナに寄生するナガクビムシ（カイアシ類）の野外における生態
  長谷川稜太
  日本陸水学会若手の会2021 (自由集会)
  20 Sep. 2021
• Condition-specific competition in native charrs: a field test considering abiotic factors and biotic interactions
  Yohsuke Uemura; Yasuhiko Otsuki; Ryota Hasegawa; Itsuro Koizumi
  The 2021 Ecological and Evolutionary Ethology of Fishes Biennial Conference, Jul. 2021
• Temperature-dependent competition in stream salmonids: a field test considering biotic interactions and abiotic factors
  Yohsuke Uemura; Yasuhiko Otsuki; Ryota Hasegawa; Itsuro Koizumi
  The 68th Annual Meeting of the Ecological Society of Japan, Mar. 2021
• 寄生虫感染個体の低いボディコンディション：原因か結果か、両方か
  長谷川稜太; 大槻泰彦; 古澤千春; 植村洋亮; 中正大; 小泉逸郎
  第68 回日本生態学会, Mar. 2021
• 河川性サケ科魚類における条件特異型種間競争：生物間相互作用および非生物的要因を考慮した野外検証
  植村洋亮; 大槻泰彦; 長谷川稜太
  2020年度日本生態学会北海道地区大会, Dec. 2020
• イワナに寄生するカイアシ類の分布規定要因と宿主への影響
  長谷川稜太; 小泉逸郎
  第36 回さけ学研究会若手企画, Dec. 2020
• 寄生虫の感染は新たな寄生虫の感染を引き起こすか：イワナとサルミンコーラを対象とした標識採捕による検証
  長谷川稜太; 大槻泰彦; 古澤千春; 植村洋亮; 中正大; 小泉逸郎
  第36 回個体群生態学会, Nov. 2020
• イワナに寄生するカイアシ類における感染率の生息地間変異：生息地の分断化に着目して
  長谷川稜太; 小泉逸郎
  第67回日本生態学会, Mar. 2020
• 寄生虫感染率の生息地間の違い：イワナに寄生するカイアシ類における瀬‐淵間比較
  村上玲央; 長谷川稜太; 大槻泰彦; 小泉逸郎; 柁原宏
  第67回日本生態学会, Mar. 2020
• イワナに寄生するカイアシ類における感染率の生息地間変異と宿主への影響
  長谷川稜太; 小泉逸郎
  第1回修士課程分野横断セミナー「生態学研究における統計解析with R, Jan. 2020
• イワナに寄生するサルミンコーラにおける感染率の生息地間変異と宿主への影響
  長谷川稜太; 小泉逸郎
  第41回魚類系統研究会, Dec. 2019
• イワナに寄生するカイアシ類における感染率の生息地間変異と宿主への影響
  長谷川稜太; 小泉逸郎
  2019年度日本生態学会北海道地区大会, Nov. 2019
• Host-patasite relationship between Salmincola caripionis and wild white-spotted char
  Ryota Hasegawa; Itsuro Koizumi
  Nord University Lunch time Seminar, Sep. 2019
• イワナの稚魚の個性は生息地間で異なるか-砂防ダムに着目して-
  長谷川稜太; 山田寛之; 守村肇; 石原千晶; 和田哲
  第66回日本生態学会, Mar. 2019

• Jul. 2021 - Present
  日本魚類学会
• Oct. 2020 - Present
  個体群生態学会
• Nov. 2018 - Present
  日本生態学会

• 宿主免疫の側面から解明する寄生虫群集の先住効果とその波及（26K24930）
  科学研究費助成事業
  Jul. 2026 - Mar. 2028
  長谷川 稜太
  日本学術振興会, 研究活動スタート支援, 北海道大学, 26K24930
• 寄生虫の寿命と繁殖をフィールドで推定する（KO2026-04）
  水産無脊椎動物研究所 個別研究助成
  Apr. 2026
  Principal investigator, KO2026-04
• Priority effects in parasite community assembly and its consequences on host fit ness and ecosystem functioning
  海外特別研究員
  Apr. 2024 - Mar. 2026
  日本学術振興会, Principal investigator
• 絶滅危惧種オショロコマに寄生するサルミンコーラの温度依存的な宿主への影響
  一般社団法人ヤンマー資源循環支援機構 研究助成
  Apr. 2023 - Mar. 2024
• 寄生虫群集の形成過程における履歴効果と宿主への波及 (JP22KJ0086)
  科学研究費助成事業
  Apr. 2022 - Mar. 2024
  長谷川 稜太
  日本学術振興会, 特別研究員奨励費, 北海道大学, JP22KJ0086
• 希少な寄生性甲殻類ヤマメナガクビムシの分布の現状把握と季節動態の解明
  厚岸町 令和4年度 厚岸湖・別寒辺牛湿原学術研究奨励補助金
  Apr. 2022 - Mar. 2023
  長谷川稜太
• Hokkaido University Ambitious Doctoral Fellowship (SDGs)
  Hokkaido University Ambitious Doctoral Fellowship (SDGs)
  Apr. 2021 - Mar. 2022
  Ryota Hasegawa
  Principal investigator
• 北海道大学大学院環境科学院環境科学同窓会 2021年度 海外学会発表支援プログラム（前期）
  Apr. 2021 - Sep. 2021
  北海道大学大学院環境科学院環境科学同窓会

• Judge of student's oral presentation (speed talk)
  31 Oct. 2025
  Review
  Academic society etc
  Department of Zoology Postgraduate Colloquium 2025
• Judge of student's oral presentation
  30 Oct. 2024 - 30 Oct. 2024
  Review
  Academic society etc
  Department of Zoology Postgraduate Colloquium 2024
• Session chair (Aquatic Parasitology in Parasites in the Pacific 2024 Conference)
  28 Aug. 2024 - 28 Aug. 2024
  Panel chair etc
  Academic society etc
• Journal of Experimental Marine Biology and Ecology
  Peer review
  Peer review etc
• Heliyon
  Peer review
• Parasitology Research
  Peer review
  Peer review etc
• Freshwater Biology
  Peer review
  Peer review etc
• International Journal for Parasitology: Parasites and Wildlife
  Peer review
• Oryx—The International Journal of Conservation
  Peer review
  Peer review etc
• タクサ：日本動物分類学会誌
  Peer review
  Peer review etc
• Canadian Journal of Zoology
  Peer review
  Peer review etc
• International Journal for Parasitology
  Peer review
  Peer review etc
• Proceedings of the Royal Society B: Biological Sciences
  Peer review
• Marine Biodiversity
  Peer review
• Proceedings of the National Academy of Sciences
  Peer review
• Journal of Fish Biology
  Peer review
• Plankton & Benthos Research
  Peer review
  Peer review etc
• Aquatic Ecology
  Peer review
  Peer review etc
• PeerJ
  Peer review
  Peer review etc
• Crustacean Research
  Peer review
  Peer review etc
• Transactions of the American Fisheries Society
  Peer review
  Peer review etc
• Molecular Biology Report
  Peer review
  Peer review etc
• 魚類学雑誌
  Peer review
  Peer review etc

• キャンパス・コンソーシアム函館（CCH）アカデミックリンク2026委員
  Apr. 2026 - Present
  Others
• サケの寄生虫に関する解説を執筆
  Oct. 2022 - Present
  Editor
  札幌市豊平川さけ科学館
• Kiwi Conservation Club (KCC) Parasite Observation
  17 Aug. 2025
  Lecturer
• Bug Day 2025
  Feb. 2025
  Lecturer
  The Entomological Society of New Zealand
• WEB魚図鑑 ボランティアスタッフ
  Jul. 2017 - Mar. 2024
  Advisor
• 写真提供「コガネシマアジ」（NHK「ギョギョッとサカナスター」）
  Oct. 2023
  Informant
• サケにつく寄生虫の展示と解説 (さけフェスタ2023)
  17 Sep. 2023
  Lecturer, Planner
  札幌市豊平川さけ科学館
• 身近な魚の寄生虫の観察
  21 Jul. 2023
  Planner, Demonstrator
  札幌市カルチャーナイト(西岡公園)
• 写真提供「ケムシカジカ」（日本テレビ「ニノさん」）
  Nov. 2020
  Informant
• 山のがっこう
  Jul. 2019
  Lecturer
  北海道コカ・コーラ
• 北海道大学総合博物館ボランティア (魚類の標本作成・管理)
  Apr. 2017 - Mar. 2018
  Investigator

• 寄生虫に感染した魚は釣られやすい？ 釣り好き大学院生が出した結論
  Mar. 2023
  朝日新聞社
  [Paper]