5. Shin-ichiro Oka
Okinawa Churashima Foundation RESEARCH INSTITUTE

Research on marine organisms

Research staff profile

Shinichiro Oka

Shin-ichiro Oka, Ph.D.

Area of
expertise		 Conservation biology, Molecular ecology
Research
content		 Research on conservation of endanger species
Technology development related to eliminate alien species
Research on biodiversity using environmental DNA

Background

  • 2021-present: Manager, Senior Research Scientist at Okinawa Churashima Foundation Research Institute
  • 2017: Ph.D., University of the Ryukyus Faculty of Science and Engineering, in special procedure
  • 2016-present: Chief Research Scientist at Okinawa Churashima Foundation Research Institute
  • 2015-2016: Part time lecturer in University of the Ryukyus
  • 2010: Research Scientist, Okinawa Churashima Foundation Research Center
  • 2000: Researcher of Biological Lab, Nishinihon Institute of Technology
  • 2000: M. Sc. in Science, University of the Ryukyus Faculty of Science and Engineering
  • 1998: B. Sc. in Marine Science, University of the Ryukyus Faculty of Science

Committee Career

  • 2019-present: Member of Secretariat, World Natural Heritage Registration Promotion Joint Venture
  • 2016-present: Committee member, Coconut Crab Conservation Ordinance Review Council in Taketomi Town
  • 2016-2020: Councilor, The Biological Society of Okinawa
  • 2011-2015: Working member, Fisheries Promotion Council of Motobu Town

Research papers, publications

  • Oka S, Nozu R, Miyamoto K, Tomita T, Hanahara N, Yamauchi C, Sasai T, Nakamura M. 2023. A trial to control invasive Mozambique tilapia populations using the sterile-male release technique in the artificial ponds on Okinawa. The Biological Magazine Okinawa, 61: 1-12.
  • Azama Y, Oka S, Teruya M, Toshino S, Tanimoto M, Hanahara N, Kuba Y, Miyagi A, Hukuchi Y. 2023. Real-time PCR assay for detection of Environmental DNA from Chironex yamaguchii. Med. Entomol. Zool., 74: 13-20.
  • Inoue T, Takanobu H, Hara Y, Nakazato K, Oka S. 2023. Tissue structure and mechanical properties of the exoskeleton of the huge claws of the mud crab, Scylla serrata. Journal of Materials Science, 58: 1099-1115.
  • Oka S, Miya M, Sado T. 2022. Gravity filtration of environmental DNA: A simple, fast, and power-free method. Methods X, 101838.
  • Omura A, Takano H, Oka S, Takei S. 2022. Quadrupedal Walking with the Skin: The Ambulatory Flaps in “Walking” Cuttlefish (Paintpot Cuttlefish, Metasepia tullbergi). 243: 44-49.
  • Ha LM, Oka S, Iguchi K. 2022. Did food resource shortage cause Ryukyu-ayu extinction on Okinawa-jima Island? A clue based on morphological approach. Ichthyological Research, 70:196-200
  • Ha LM, Oka S, Iguchi K. 2022. Did food resource shortage cause Ryukyu-ayu extinction on Okinawa-jima Island? A clue based on morphological approach. Ichthyological Research, 69: 381-386
  • Miya M, Sado T, Oka S, Fukuchi T. 2022. The use of citizen science in fish eDNA metabarcoding for evaluating regional biodiversity in a coastal marine region: A pilot study. Metabarcoding & Metagenomics,6: e80444
  • Inoue T, Oka S, Nakazato K, Hara T. 2022. Columnar Structure of Claw Denticles in the Coconut Crab, Birgus latro. Minerals, 12: 274
  • Inoue T, Oka S, Nakazato K, Hara T. 2021. Structural Changes and Mechanical Resistance of Claws and Denticles in Coconut Crabs of Different Sizes. Biology, 10: 1304
  • Oka S, Tokutake K, Inoue T. 2021. Growth analysis and population size estimation of coconut crabs based on a large recapture dataset. Crustacean Research, 50: 145-150
  • Ha LM, Oka S, Iguchi K. 2021. Fluctuating asymmetry in the insular population of ayu, Plecoglossus altivelis ryukyuensis, estimating its genetic diversity at extinction. Ichthyological Research, in press.
  • Sasai T, Yamamoto T, Oka S, Toda M. 2021. Addition of the Sea Snake, Hydrophis stokesii (Reptilia: Squamata: Elapidae), to the Herpetofauna of Japan. Current Herpetology, 40:190-196.
  • Inoue T, Hara T, Nakazato K, Oka S. 2021. Superior mechanical resistance in the exoskeleton of the coconut crab, Birgus latro. Materials Today Bio, 100132.
  • Inoue T, Oka S, Hara T. 2021. Three-dimensional microstructure of robust claw of coconut crab, one of the largest terrestrial crustaceans. Materials & Design, 206, 109765.
  • Oka S, Sasai T, Hanahara N, Miyamoto K, Kobayashi Y, Murata N, Maeda K. 2021. Genetic traits of the weatherfish Misgurnus sp. OK on the Okinawa Islands, southern Japan. Fauna Ryukyuana. 59: 57–61.
  • Hanahara N, Miyamoto K, Oka S. 2021. Northernmost record of the surgeonfish Acanthurus nigros (Teleostei: Acanthuridae) from Minamidaitojima Island, southern Japan. Species Diversity. 26: 43–47. doi: 10.12782/specdiv.26.43
  • Hanahara N, Miyamoto K, Oka S. 2020. Morphological and genetic identification of formalin-fixed gobioid larvae and description of postflexion larvae of Paragunnellichthys sp. and Ctenogobiops feroculus. Ichthyological Research. 68: 182–190. doi: 10.1007/s10228-020-00769-z
  • Oka S, Doi H, Miyamoto K, Hanahara N, Sado T, Miya M. 2021. Environmental DNA metabarcoding for biodiversity monitoring of a highly diverse tropical fish community in a coral reef lagoon: Estimation of species richness and detection of habitat segregation. Environmental DNA. 3:55-69. doi: 10.1002/edn3.132
  • Oka S, Nakamura M, Nozu R, Miyamoto K. 2020. First observation of larval oarfish, Regalecus russelii, from fertilized eggs through hatching, following artificial insemination in captivity. Zoological letters. 6: 1-6. doi: 10.1186/s40851-020-00156-6
  • Oka S, Kobayashi N, Sato T, Ueda K, Yamagishi M. 2019. Sound production in the coconut crab, the largest terrestrial crustacean. Zoology. 137: 125710. doi: 10.1016/j.zool.2019.125710
  • Doi H, Fukaya K, Oka S, Sato K, Kondoh M, Miya M. 2019. Evaluation of detection probabilities at the water-filtering and initial PCR steps in environmental DNA metabarcoding using a multispecies site occupancy model. Scientific Reports. 9: 3581. doi: 10.1038/s41598-019-40233-1.
  • Tomita T, Toma H, Murakumo K, Yanagisawa M, Yano N, Oka S, Miyamoto K, Hanahara N, Sato K. 2018. Captive Birth of Tiger Shark (Galeocerdo cuvier) Revealed the Shift of Respiratory Mode Across Parturition. Copeia. 106: 296-296.
  • Oka S, Hanahara N, Shintani T. 2018. First Japanese record of the Mindoro snake eel Lamnostoma mindorum (Actinopterygii: Anguilliformes: Ophichthidae) from the Ryukyu Islands. Fauna Ryukyuana. 42: 5-8.
  • Tomita T, Toda M, Miyamoto K, Oka S & Sato K. 2018. Development of lunate-shape caudal fin in White shark embryo. The Anatomical Record. 301: 1068-1073. DOI: 10.1002/ar.23776
  • Miyamoto K, Oka S, Yonamine H, Agarie R, Genba H. Hanahara N. 2017. A high-density habitat and genetic characteristics of the Oriental weatherfish, Misgurnus anguillicaudatus, and the Asian swamp eel, Monopterus albus, found in Nago City, Okinawa-jima Island, southwestern Japan. Fauna Ryukyuana. 34: 15-20.
  • Tomita T, Miyamoto K, Kawaguchi A, Toda M, Oka S, Nozu R, Sato K. 2017. Dental ontogeny of white shark embryo. Journal of Morphology. 278 (2): 215-227. doi: 10.1002/jmor.20630
  • Oka S, Tomita T, Miyamoto K. 2016. A mighty claw: Pinching force of the coconut crab, the largest terrestrial crustacean. PLOS ONE. 11(11): e0166108. doi: 10.1371/journal.pone.0166108.
  • Miya M, Minamoto T, Yamanaka H, Oka S, Sato K, Yamamoto S, Sado T, Doi H. 2016. Use of a filter cartridge for filtration of water samples and extraction of environmental DNA. Journal of Visualized Experiments. e54741. doi:10.3791/54741.
  • Oka S, Miyamoto K, Matsuzaki S. 2016. Long-term sedentary behavior of coconut crab in their northernmost range. International Journal of Pure and Applied Zoology. 4: 174-178.
  • Oka S, Miyamoto K, Tokutake K, Nagata S, Yamazaki K. 2016. The nature outreach using the wild coconut crab resource in Ocean Expo Park, Okinawa, Japan. Environmental Education. 26: 78-84.
  • Tomita S, Matsuzaki S, Oka S, Toda M, Imai H. 2016. High levels of genetic diversity and gene flow in the endangered goby Hypseleotris cyprinoides on Okinawajima Island, Ishigakijima Island and Luzon Island. Japanese Journal of Ichthyology., 63: 27–32.
  • Tomita T, Murakumo K, Miyamoto K, Sato K, Oka S, Kamisako H & Toda M. 2015. Eye retraction in the giant guitarfish, Rhynchobatus djiddensis (Elasmobranchii: Batoidea): a novel mechanism for eye protection in batoid fishes. Zoology. 119(1): 30-35. DOI: 10.1016/j.zool.2015.09.004
  • Miyamoto K, Nonaka A, Oka S. 2015. Northernmost record of a poorly known tuskfish Choerodon margaritiferus (Perciformes: Labridae), from southern Japan, and first description of a female. Zootaxa. 4007(1): 82-90. DOIi: 10.11646/zootaxa.4007.1.5
  • Oka S, Miyamoto K. 2015. Reproductive biology and growth of bluestripe herring Herklotsichthys quadrimaculatus (Rüppell, 1837) in the northernmost waters. Journal of Applied Ichthyology. 31(4): 709-713. doi: 10.1111/jai.12811.
  • Oka S, Miyamoto K, Matsuzaki S, Sato T. 2015. Growth of the coconut crab, Birgus latro, at its northernmost range estimated from mark-recapture using individual identification based on carapace grooving patterns. Zoological Science. 32: 260-265.
  • Oka S. & Miyamoto K. 2015. Pelagic juvenile of Plectroglyphidodon johnstonianus Flower & Ball, 1924 (Perciformes, Pomacentridae, Stegastinae) identified from morphometric and genetic evidence. Fauna Ryukyuana. 20:1-6.
  • Miyamoto K, Oka S. 2014. Occurrence of Gerres macracanthus (Perciformes: Gerreidae) from Okinawa Island, Ryukyu Archipelago, Japan. Fauna Ryukyuana. 17: 1-6.
  • Oka S, Miyamoto K. 2014. Larvae and juvenile fishes collected by light-trap sampling at Shinzato Port, Okinawa Island, southern Japan. Fauna Ryukyuana. 16: 1-11.
  • Oka S, Odoriba S. 2014. Morphological development of larval and juvenile Alectis indica (Perciformes: Carangidae) reared in captivity. Ichthyological Research. 61: 298-302. DOI 10.1007/s10228-014-0397-8
  • Oka S, Matsuzaki S, Miyamoto K. 2014. Current status of the coconut crab, Birgus latro (Anomura: Coenobitidae) in Ocean Expo Park, Okinawa-jima Island, southwestern Japan. Biological Magazine of Okinawa. 52: 11-19.
  • Oka S, Matsuzaki S, Toda M. 2013. Identification of individual coconut crabs, Birgus latro, on the basis of the pattern of grooves on the carapace. Crustacean Research. 42: 17-23.
  • Kawazu I, Maeda K, Kino M, Oka S. 2013. Structure of the Loggerhead Turtle Assemblage in Okinawan Waters Estimated from Variation in Body Size and Blood Profile. Current Herpetology. 32: 190-196. DOI: 10.5358/hsj.32.190
  • Oka S, T Higashiji. 2012. Early ontogeny of the big roughy Gephyroberyx japonicus (Beryciformes: Trachichthyidae) in captivity. Ichthyological Research, 59: 282-285. DOI: 10.1007/s10228-012-0282-2
  • Oka S, Tachihara K. 2008. Migratory history of the spotted flagtail, Kuhlia marginata. Environmental Biology of Fishes. 81(3):321-327. DOI: 10.1007/s10641-007-9203-z

Books

  • Oka S. 2021. Practice and potential in coral reef lagoon with high fish species diversity, pp169-181. H Doi & M Kondoh (eds). Enviromental DNA. Kyoritsu Shuppann. (in Japanese)
  • Oka S, Shared writing, 2014. An atlas of early stage fishes in Japan, second edition. Tokai University Press. (in Japanese)
  • Oka S. 2007. “Mikiu” Flag tail and Jungle perch. pp152-154. S Shokita & K Tachihara (eds) . River Ecology and Conservation in Ryukyus. Ryukyu-ayu Restorative Association. (in Japanese)

Affiliated academic society

  • The Ichthyological Society of Japan
  • Carcinological Society of Japan
  • The eDNA Society

Patent

  • “Fish Collection System” No. 6498468 in Japanese Government

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