Researcher Profile and Settings

Affiliation

• Faculty of Fisheries Sciences　Marine Bioresource and Environmental Science　Interdisciplinary Sustainability Studies

Job Title

• Assistant Professor

J-Global ID

• 201501008116776941

Research Interests

• Applied Ecology   Sustainability   Resource Dynamics Analyses and Monitoring   Fisheries Cooperation   Fisheries Development   

Research Areas

• Environmental science/Agricultural science / Biological resource conservation / Ecosystem Approach/Ecosystem Based Approach
• Life sciences / Aquaculture / Fisheries Development and Cooperation Practices

Educational Organization

•  Bachelor's degree program　School of Fisheries Sciences
•  Master's degree program　Graduate School of Fisheries Sciences
•  Doctoral (PhD) degree program　Graduate School of Fisheries Sciences

Academic & Professional Experience

• 2015/07 - Today Hokkaido University International Education Office, Faculty of Fisheries Sciences Research Associate
• 2013/04 - 2015/06 (Dispatched Expert of Japan International Cooperation Agency) The Project IMPM: Capacity Development of Fisheries Resources Monitoring for Sustainable Management of Small Pelagic Resources in the Kingdom of Morocco Deputy Chief of the Project/Expert in Resource Dynamics Analyses and Monitoring
• 2010/09 - 2013/03 (Dispatched Expert of Japan International Cooperation Agency) The Project IMPM: Capacity Development of Fisheries Resources Monitoring for Sustainable Management of Small Pelagic Resources in the Kingdom of Morocco Project coordinator/Expert in Ecosystem Monitoring

Education

• 2006/10 - 2009/09  Hokkaido Univeristy  Graduate School of Env.Science
• 2002/09 - 2006/05  University of Alaska Fairbanks  School of Fisheries and Ocean Sciences
• 1997/09 - 2001/05  University of Idaho  College of Natural Resources
• 1992/04 - 1996/03  Kinki University  Faculity of Literature, Arts and Cultural Studies  Department of Cultural Studies

Research Activities

Published Papers

• The effect of farm size on economic efficiency: a case study of Vietnamese pangasius farms

  Huynh Huu Tho, Nguyen Le Hoa Tuyet, Naoki Tojo

  Fisheries Science (online) : https://doi.org/10.1007/s12562-021-01549-y 2021/09 [Refereed]
  
• Are Consumers Willing to Pay More for Traceability? Evidence from an Auction Experiment of Vietnamese Pork

  Khuu, Thi, Phuong Dong, Saito, Yoko, Tojo, Naoki, Nguyen, Phuong Duy, Nguyen, Thi Ngoc Hoa, Matsuishi, Takashi Fritz

  International Journal of Food and Agricultural Economics 7 (2) 127 - 140 2019/04 [Refereed]
  
• Genetic population structure of the European anchovy (Engraulis encrasicolus) based on mitochondrial DNA sequences along the Moroccan coast

  Khalil C. OUAZZANI, Touria BENAZZOU, Lina TAZ, Naoki TOJO, Malika CHLAIDA

  AACL Bioflux 9 (5) 1133 - 1143 2016 [Refereed]
  
• Seasonal and size-dependent variability in diet of Scomber colias (Gmelin, 1789) of the Atlantic Coast of the Northwest Africa

  Fatima WAHBI, Naoki TOJO, Azeddine RAMZI, Laila SOMOUE, Khalid MANCHIH, Ahmed ERRHIF

  International Journal of Advanced Research 3 (12) 485 - 497 2015 [Refereed]
  
• 音響反射強度測定による来留見ノ瀬のホンダワラ科藻場の現存量推定と季節変化．

  南憲吏, 安間洋樹, 濱野明, 中村武史, 村瀬昇, 東条斉興, 宮下和士

  海洋音響学会誌 42 1 - 10 2015 [Refereed][Not invited]
  
• Distribution of sei whales (Balaenoptera borealis) in the subarctic-subtropical transition area of the western North Pacific in relation to oceanic fronts

  Hiroto Murase, Takashi Hakamada, Koji Matsuoka, Shigetoshi Nishiwaki, Denzo Inagake, Makoto Okazaki, Naoki Tojo, Toshihide Kitakado

  DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY 107 22 - 28 0967-0645 2014/09 [Refereed][Not invited]
   

  The subarctic-subtropical transition area of the western North Pacific is an important summer feeding grounds of sei whales. The oceanographic structure and circulation of this area are largely determined by strong oceanic fronts and associated geostrophic currents, namely the Polar Front (PF), Subarctic Front (SAF) and Kuroshio Extension Front (KEF). The relationship between the distribution of sei whales and oceanographic fronts was investigated using a generalized additive model (GAM), and the cetacean sighting survey data and oceanographic observations in July from 2000 to 2007 were used in the analysis. The number of individual sei whales was used as the response variable while the distances from the PF, SAF, and KEF to the whales were used as explanatory variables along with the longitude values. Sei whales were concentrated north and south of the SAF and the areas from 250 to 300 km north and from 100 to 200 km south of the SAF were estimated as high-density areas of sei whales. The entire inter-frontal zone between the PF and SAF featured an elevated concentration of sei whales, and the area south of the PF and along the SAF was identified as an important feeding ground of sei whales in July from 2000 to 2007. (C) 2014 Elsevier Ltd. All rights reserved.
• Quantitative mapping of kelp forests (Laminaria spp.) before and after harvest in coastal waters of the Shiretoko Peninsula, Hokkaido, Japan

  Kenji Minami, Naoki Tojo, Hiroki Yasuma, •Yusuke Ito, Takahiro Nobetsu, Shin-ichi Fukui, Kazushi Miyashita

  Fisheries Science Springer 80 (3) 405 - 413 0919-9268 2014 [Refereed][Not invited]
   

  In the Shiretoko Peninsula, a World Natural Heritage site, the sustainable management of kelp forests has drawn public attention because of the economic and ecological importance of kelp. We spatially estimated the distributions of kelp forests in the Shiretoko Peninsula before and after harvest. Field surveys were conducted in coastal waters (23.74 km(2)) at the ends of July and August 2008, immediately before and after harvest. Data on the presence or absence and thickness of the kelp forests were collected via acoustic observation. The data were interpolated using geostatistical methods. Before harvest, the kelp forests were continuously distributed over 5.64 km(2) (thickness 33-132 cm), especially near the north part of the study area. After harvest, they were sparsely distributed over 2.73 km(2) (thickness 35-105 cm). In the southern part of the study area, the influence of harvests was observed as declines in forest area. In addition, relatively thickly forested areas formed the majority of the part most likely to be harvested. Selective harvesting for area and size was confirmed though quantitative mapping of kelp forests. The quantitative mapping of both the distribution and harvest of kelp forests was successful.
• 音響手法を用いた来留見ノ瀬周辺におけるガラモ場の分布推定

  南 憲吏, 濱野 明, 東条斉興, 中村武史, 安間洋樹, 宮下和士

  日本水産学会誌 78 171 - 179 2012/04 [Refereed][Not invited]
  
• Estimation of the spatial distribution of a Sargassum bed in Kuruminose, Yamaguchi, Japan, using an acoustic method

  Kenji Minami, Akira Hamano, Naoki Tojo, Takeshi Nakamura, Hiroki Yasuma, Kazushi Miyashita

  NIPPON SUISAN GAKKAISHI 78 (2) 171 - 179 0021-5392 2012/03 [Refereed][Not invited]
   

  Sargassum beds play important ecological roles as nursery grounds, feeding grounds and hiding grounds for coastal fauna in Kuruminose, Yamaguchi, Japan (12 km(2)). In this study, we tried to estimate the spatial distribution of a Sargassum bed using an acoustic method. For this purpose, binarization and geostatistical methods were used. The binarization provided the optimum thresholds to separate the bottom and head of the Sargassum bed. The bottom threshold and the head threshold were -22.4 dB, and -56.4 dB, respectively. The horizontal distribution was interpolated every 1 m(2) using kriging. The area of the Sargassum bed was estimated to be 1.94 km(2), with thickness of 0.50 to 2.24 m. The Sargassum bed in the south-southeast of Kuruminose was thicker and larger than that near Kuruminose, suggesting that the south-southeast Sargassum bed is important for the coastal ecosystem in Kuruminose. The estimated thickness and distribution corresponded with those by direct observation by diving and underwater TV camera, suggesting that acoustic measurement is adequate for estimating the spatial distribution of Sargassum beds.
• 音響手法を用いたコンブ場の高さ計測

  南憲吏, 安間洋樹, 東条斉興, 伊藤祐介, 福井信一, 野別貴博, 宮下和士

  数理水産科学 9 62 - 74 2012 [Refereed][Not invited]
  
• Spatial estimation of euphausiid abundance of Pacific coast off Hokkaido,Japan in early summer of 2008

  Naoki Tojo, Kenji Minami, Ryuichi Matsukura, Yohei Kawauchi, Tetsuichiro Funamoto, Masayuki Chimura, Akira Nishimura, Kazushi Miyashita

  Journal of Marine Science and Technology 19 294 - 301 2011 [Refereed][Not invited]
  
• Vertical distribution of walleye pollock juvenile before and after the period of transition for feeding in Funka bay, Hokkaido, Japan

  Yohei Kawauchi, Osamu Shida, Yuya Okumura, Naoki Tojo, Hiroki Yasuma, Kazushi Miyashita

  Journal of Marine Science and Technology 19 279 - 286 2011 [Refereed][Not invited]
  
• Estimation of kelp forest, Laminaria spp., distributions in coastal waters of the Shiretoko Peninsula, Hokkaido, Japan, using echosounder and geostatistical analysis

  MINAMI Kenji, YASUMA Hiroki, TOJO Naoki, FUKUI Shin-ichi, ITO Yusuke, NOBETSU Takahiro, MIYASHITA Kazushi

  Fisheries Science Springer Japan 76 (5) 729 - 736 0919-9268 2010/09 [Refereed][Not invited]
   

  Sustainable management of the kelp forests of the Shiretoko Peninsula, a World Natural Heritage site, is necessary due to kelp's ecological and economic importance. The objectives of this study were to estimate the area of kelp forests and to clarify their spatial characteristics in coastal waters of the Shiretoko Peninsula. Data on the presence/absence and thickness of kelp forests were collected via acoustic observation on transects over about 80 km using an echosounder at 200 kHz. Acoustic data were geostatistically interpolated, and the areas covered by kelp forests were estimated. Differences in kelp distribution between the eastern and western sides of the peninsula were compared. The total area of kelp forest was 3.88 km2 (eastern area: 3.49 km2; western area: 0.39 km2). The range of thickness of the kelp forests was 34-91 cm. Many kelp forests in the eastern area were thick (>78 cm) and distributed continuously, while kelp forests in the western area were sparsely distributed.
• Age-dependent distribution of juvenile southern bluefin tuna (Thunnus maccoyii) on the continental shelf off southwest Australia determined by acoustic monitoring

  HONDA Kentaro, HOBDAY Alistair J, KAWABE Ryo, TOJO Naoki, FUJIOKA Ko, TAKAO Yoshimi, MIYASHITA Kazushi

  Fisheries Oceanography 19 (2) 151 - 158 1054-6006 2010 [Refereed][Not invited]
   

  Juvenile southern bluefin tuna (Thunnus maccoyii, SBT) were monitored in nearshore waters off southwest Australia using acoustic tagging and monitoring over five austral summers (2002/2003-2006/2007) to determine patterns in age-based distribution of SBT. A total of 20-70 receivers were deployed in early December along one to three cross-shelf transects and at three inshore topographic features (lumps) where SBT are known to occur; and a total of 59-84 juvenile SBT (41-90 cm fork length) were tagged and released each year. After several months, receivers were recovered, and data extracted. In 2002/2003 and 2003/2004, 2-yr-old SBT were detected more frequently in nearshore areas than did 1-yr old fish. Similarly in 2004/2005 and 2006/2007, it was the larger 1-yr-old SBT that were detected more frequently at inshore lumps (> 85% of detections) while small 1-yr-old SBT were detected more widely over the study area. In 2005/2006, although large 1-yr-old SBT were still detected more frequently at inshore lumps than small 1-yr old SBT, the percentage of all detections at lumps was lower at 31.5%, indicating wider distribution of both small and large age-1 fish. The observed age-dependent distribution pattern may be enhanced by the distribution of prey, which disperse or concentrate depending on the local oceanography.
• River environmental factors against seasonal habitat use of adult Sakhalin taimen (Huch perryi) in Bekanbe-ushi river system, Japan

  Kentaro Honda, Haruka Kagiwada, Naoki Tojo, Kazushi Miyashita

  Journal of Fish Biology Blackwell Publishing 77 (7) 1526 - 1541 0022-1112 2010 [Refereed][Not invited]
   

  The study identified seasonal habitat use by endangered adult Sakhalin taimen, Hucho perryi and the environmental characteristics of their habitats (water depth, amount of riparian forest, and meandering sinuosity). Fifteen adult H. perryi with acoustic tags were tracked by towing an acoustic receiver with a canoe in the Bekanbeushi River system in eastern Hokkaido Island, Japan during each month from late April to late November 2008. Individuals mainly used midstream (shallower than downstream) habitats in all seasons. These locations were generally characterized by relatively dense riparian forests and high sinuosity, indicating the presence of pools. In spring, individuals used habitats with less riparian forest cover compared to mean value of the river channel. From spring to autumn, adult H. perryi selected limnologically complex habitats with meandering channels. From summer to autumn, individuals selected habitats with more riparian forest cover. The inverse relationship between H. perryi detection and riparian forest area in spring was a result of seasonal defoliation in deciduous riparian forests.
• “Spatial analysis of Isada Krill (Euphausia pacifica) distribution in frontal environments in the North Pacific Ocean”

  Naoki TOJO, Ryuichi MATSUKURA, Hiroki YASUMA, Shiroh YONEZAKI, Hikaru WATANABE, Shigeyuki KAWAHARA, Hiroto MURASE, Kazushi MIYASHITA

  GIS/Spatial analyses in Fishery and Aquatic Science 4 115 - 118 2010 [Not refereed][Not invited]
  
• “Quantitative analysis of Isada krill (Eupausia pacifica) distribution in the western North Pacific”

  Naoki TOJO, Daisuke SHIMIZU, Hiroki YASUMA, Shigeyuki KAWAHARA, Hikaru WATANABE, Shirou YONEZAKI, Hiroto MURASE, Kazushi MIYASHITA

  Bulletin of the Japanese Society of Fisheries Oceanography 72 (3) 165 - 173 2008 [Refereed][Not invited]
  
• Migration dynamics of Pacific herring (Clupea pallasii) and response to spring environmental variability in the southeastern Bering Sea

  Naoki Tojo, Gordon H. Kruse, Fritz C. Funk

  DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY 54 (23-26) 2832 - 2848 0967-0645 2007 [Refereed][Not invited]
   

  In the southeastern Bering Sea. Pacific herring (Clupea pallasii) migrate from the Pribilof Islands region where they overwinter, to the Alaska coast where they spawn in spring. The migration sustains a nearshore commercial fishery that targets roe-bearing females just prior to spawning. Herring also are taken as bycatch in groundfish trawl fisheries, where time and area closures in these fisheries are triggered by herring bycatch caps. Using herring bycatch data collected since the 1970s by National Marine Fisheries Service (NMFS) observers aboard groundfish fishing vessels, a retrospective analysis was conducted to describe the seasonal migration pattern of Pacific herring in the southeastern Bering Sea and to study its spatial and temporal variability. Observed changes in herring catch per unit of effort were compared with variability in climate and oceanographic conditions. The seasonal migration is complex, but annual shifts in migration routes and a possible northward shift of the overwintering grounds was identified. Pre-spawning herring aggregated in different areas depending on whether spawning occurred early or late in spring. The thermal structure of the ocean around the ice edge appears to influence herring migration timing and route as well as spawning date. Thus, on the basis of recent changes in sea-ice extent and duration, we suggest that the herring bycatch savings area that was developed from data collected in the 1980s should be revised to reflect prevailing conditions. (C) 2007 Elsevier Ltd. All rights reserved.

MISC

• 計量魚群探知機を用いたガラモ場の現存量推定

  南 憲吏, 安間洋樹, 濱野 明, 東条斉興, 中村武史, 宮下和士  海洋音響学会2012年度研究発表会講演論文集  1  -2  2012/06  [Not refereed][Not invited]
  
• Prey selection of common minke, Bryde's and sei whales in the offshore region of the western North Pacific

  村瀬 弘人, 田村 力, 磯田 辰也, 岡本 亮介, 加藤 秀弘, 米崎 史郎, 渡邉 光, 東条 斉興, 松倉 隆一, 宮下 和士, 木和田 広司, 松岡 耕二, 西脇 茂利, 稲掛 伝三, 岡崎 誠, 岡村 寛, 藤瀬 良弘  水産海洋研究  75-  (3)  180  -181  2011/08/01
• 計量魚探による鯨類餌生物のモニタリング

  宮下和士, 松倉隆一, 東条斉興, 南憲吏, 安間洋樹, 永島宏, 小野寺恵一, 渡邉 光, 米崎史郎, 村瀬弘人  水産海洋研究  75-  183  -184  2011  [Not refereed][Not invited]
  
• 北西太平洋沖合域におけるミンククジラ，イワシクジラ，ニタリクジラの餌選択性

  村瀬弘人, 田村力, 磯田辰也, 岡本亮介, 加藤秀弘, 米崎史郎, 渡邉光, 東条斉興, 松倉隆一, 宮下和士, 木和田広司, 松岡耕二, 西脇茂利, 稲掛伝三, 岡崎誠, 岡村寛, 藤瀬良弘  水産海洋研究  75-  183  -184  2011  [Not refereed][Not invited]
  

Awards & Honors

• 2015/02 Ministère de l'agriculture et de la pêche maritime, Maroc (Kingdom of MOROCCO) (Special Award for the Cooperative Activities as a Expert in the Fisheries Project)
   

  受賞者: Naoki TOJO
• 2007/11 North Pacific Marine Science Organization (PICES) FIS Committee Best Presentation Award
   "Marine environment induced spatial dynamics of recruited walleye pollock juveniles (Theragra chalcogramma) and interactions with prey and predators along the Pacific coast of Hokkaido, Japan" 

  受賞者: Naoki TOJO (Authors;Naoki Tojo;Akira Nishmura;Satoshi Honda;Tetsuichiro Funamoto;Seiji Katakura;Kazushi Miyashit

Educational Activities

Teaching Experience