Research Themes

• 生徒のキャリア教育と漁業担い手確保に向けた調査を両立させる研究開発
  科学研究費助成事業
  01 Apr. 2025 - 31 Mar. 2028
  福田 覚, 山下 俊介, 宮下 和士
  日本学術振興会, 基盤研究(C), 北海道大学, 25K06214
• 音響手法を用いたダム湖の水質悪化要因となるアオコの分布推定手法の開発
  科学研究費助成事業
  01 Apr. 2020 - 31 Mar. 2023
  南 憲吏, 宮下 和士
  藍藻類が異常繁殖した状態であるアオコは、ダム湖の水質悪化の原因となる。本研究は、アオコの分布を空間的かつ定量的に評価することを目指した、音響計測手法を用いたアオコの分布推定手法の開発を目的とする。本年度は、2020年度に取得した音響反射強度および藍藻類の細胞数に関する情報の解析を進めた。これにより、藍藻類の細胞数と音響反射強度の間に関係性が示され、藍藻類以外の植物プランクトンや動物プランクトンと音響反射強度の間には関係性がみられないことが明らかとなった。このことから、音響反射強度を定量的に計測可能な計量魚群探知機によるアオコの分布推定が有効であることが示された。また、本年度も昨年度に引き続き、アオコの音響反射強度および細胞数に関する調査の実施を予定していた。調査は、福島県田村郡三春町の三春ダムにおいてアオコが一年のうちで最も多くなる夏季（8月）に実施する計画で進めた。本計画では、中程度のアオコが発生している地点において周波数38kHzおよび120kHzの計量魚群探知機を用いた音響計測、バンドン式採水器（植物プランクトン用サンプル採集）とシンドラープランクトントラップ（動物プランクトン用サンプル採集）によるサンプリングをおこない、2020年度と同様に藍藻類の細胞数と音響反射強度に関係性があるかについて明らかにする予定であった。しかし、新型コロナウイルス感染症の拡大時期と重なり、調査の中止を余儀なくされ、2022年度の調査に持ち越すこととなった。
  日本学術振興会, 基盤研究(C), 島根大学, 20K06207
• Construction of the monitoring system on stream ecology using RFID
  Grants-in-Aid for Scientific Research
  01 Apr. 2014 - 31 Mar. 2017
  MIYASHITA Kazushi
  We constructed monitoring system for a passive type and an active type using radio waves. Active RFID can be used up to the depth of 60 cm in fresh water. We developed a device for decode to radio wave. In addition, we obtained insight to use active RFID. We implemented integration of device by middleware in the case of monitoring with different conditions. Furthermore, the compression sensing for monitoring for wide area monitoring and data collection assuming was verified.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 26292103
• 海洋生態系の動態解析に関する研究　　　　　　　　　　　　　　　
  2002 - 2017
  Competitive research funding
• 海洋生物資源の空間的可視化技術の高度化に関する研究　　　　　　　　　　　　　　　
  1998 - 2017
  Competitive research funding
• 海洋生物資源の持続的利用に関する研究　　　　　　　　　　　　　　　
  1998 - 2017
  Competitive research funding
• 海洋生物の行動計測に関する研究　　　　　　　　　　　　　　　
  1997 - 2017
  Competitive research funding
• Seasonal migration in the Pacific giant octopus Enteroctopus dofleini
  Grants-in-Aid for Scientific Research
  01 Apr. 2013 - 31 Mar. 2016
  SANO Minoru, Itaya Kazuhiko, Uchida Yasuhito, Koshimizu Kenichi, Miyashita Kazushi, Bando Tadao
  Seasonal migration characteristics of the North Pacific giant octopus, Enteroctopus dofleini (Wülker, 1910), were investigated in the Soya/La Perouse Strait. We conducted capture-recapture surveys using a temperature logger to infer migration patterns for this species, examined the stomach contents of captured individuals, and identified sessile organisms on the sea bottom by sonar and digital camera observations. In addition, we reared octopuses at several water temperatures in temperature-controlled tanks to examine the relationship between temperature and growth rate. The findings showed that octopuses start migrating to deep areas at water temperatures >15°C. No octopuses were observed in shallow areas at temperatures >= 21°C in the Soya/La Perouse Strait. In autumn, when the water temperatures in shallow areas decreased below 19°C, the octopuses appeared to return to these areas in search of food, remaining there from winter to spring.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido Research Organization, 25450288
• Development of acoustic technique for biomass monitoring of seaweed bed, sea grass bed and kelp bed
  Grants-in-Aid for Scientific Research
  01 Apr. 2011 - 31 Mar. 2014
  MIYASHITA KAZUSHI, FUJIMORI Yasuzumi, KIMURA Nobuo
  In coastal area, Sargassum spp., Zostera spp. and Laminaria spp. forms dense vegetation community, which are called as seaweed bed, seagrass bed and kelp bed. In this study, we estimated the characteristics and the wave shapes of acoustic intensity of these beds, and then we developed the discriminate method of these beds by acoustic technique using the characteristics. In the result, it was suggested that the discrimination of the beds is possible using a two-stage approach. The first stage is the discrimination of the area backscattering (Seaweed bed; -33.3~-57.0 dB, Seagrass bed; -39.2~-66.1 dB, Kelp bed; -59.8~-74.3 dB). In the second stage is the discrimination of the wavelet coefficient of Lv. 4 (Seagrass bed; 12000-39000, Kelp bed; 3000-12000). This method may allow better biomass estimation of these beds by acoustic technique.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 23380108
• Construction of multidimensional network to monitor northern marine ecosystem using top predators
  Grants-in-Aid for Scientific Research
  2010 - 2012
  MIYASHITA Kazushi, MITANI Yoko, WATANUKI Yutaka, YONEZAKI Shiroh, HATTORI Kaoru
  We conducted monitoring of top predators, such as seabirds and marine mammals undertaking extensive migration for foraging in northern marine ecosystem by using various instruments and analyses. Movement patterns and feeding ecology varied among individuals and areas even of the same species. These variations may affect the success of reproduction and survival of each individual. Our study contributes to understanding of marine environmental change by monitoring via top predators.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 22405007
• Establishment of metacommunity approach toward conservation of coastal biological community in varying environment
  Grants-in-Aid for Scientific Research
  2009 - 2012
  NAKAOKA Masahiro, TANAKA Norio, HORI Masakazu, YOTSUKURA Norishige, MIYASHITA Kazushi, ISODA Yutaka, NODA Takashi, NADAOKA Kazuo, YAMAMOTO Tomoko, HAMAGUCHI Masami
  To provide scientific information for the conservation and management of coastal ecosystems and resources, the present study carried out an integrated approach to investigate structure and dynamics of coastal marine community and their changes in relation to global climate change such as temperature rise. We specially targeted on seagrass bed, rocky intertidal and kelp forest communities as model systems. We conducted broad-scale, long-term monitoring of these communities based on periodical census and the use of remote sensing and GIS analyses, statistical analyses on meta-community structure, genetic analyses based on molecular data, and field manipulative experiments. The results demonstrated that structures of coastal communities are affected by multiple factors that operate at different spatial scales, and that their dynamics can be unstable with ongoing climate change through modification of species interaction processes between producers and consumers.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 21241055
• Development of adaptive marine ecosystem management and co-management plan in Shiretoko World Natural Heritage Site : Interaction between land and marine ecosystems
  Grants-in-Aid for Scientific Research
  2006 - 2009
  SAITOH Sei-ichi, KAERIYAMA Masahide, SAKURAI Yasunori, MATSUDA Hiroyuki, WATANUKI Yutaka, MIYASHITA Kazushi, KONO Tokihiro, KUDO Hideaki, HIRAWAKE Toru, SHIOMOTO Akihiro, YAMAMOTO Jun
  We carried out the development of monitoring methods on marine life and their environment and promoted various field observations in Shiretoko World Natural Heritage (SWNH) area. As a result, it is clear that there is difference in primary production system between northern coastal region and southern coastal region. We clarified 1) the effect of Pacific salmon (Genus Oncorhynchus) escapement on supply of marine-derived nutrients to the riparian ecosystems using the stable isotope analysis, and 2) to estimate escapement dynamics and spawning carrying capacity of the wild pink salmon (O.gorbusha) relating to the feeding behavioral pattern of brown bear (Ursus arctos) in SWNH area. Based on the adaptive marine ecosystem management, we proposed new method to evaluatean optimum fisheries operation for each fish species using both catch of fish and haul of fish in the Shiretoko coastal fisheries.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 18201006
• 多次元定量計測技術を用いた絶滅危惧種イトウの行動生態の解明
  科学研究費助成事業
  2006 - 2007
  宮下 和士, 帰山 雅秀, 田中 秀二
  本研究では,イトウの生息範囲を正確にとらえ,そのデータを活用した生態学的なアプローチにより,本種の行動メカニズムを明らかにし,将来的な保護や周辺環境の保全に寄与する情報を得ることを目的とし,バイオテレメトリー手法を用いてイトウの正確な位置・時間とその移動の情報を収集・蓄積した。
  調査は,厚岸郡厚岸町の別寒辺牛川水系において,2006年4月下旬から同年12月上旬,2007年4月下旬から同年11月下旬の期間に行った。イトウは2006年に2個体、2007年に5個体捕獲し,超音波発信器を装着した。超音波受信機を河川内の定点(間隔約2km〜5km)に設置し,並行してカヌーの舷側に取り付け,GPSで位置情報を取得しながら河川内を移動した。
  受信機データから放流した全個体の受信が確認でき,受信回数は2006年に130回,2007年に37,683回であった。産卵後の降下行動の平均時間は44.1±29.1時間(Mean±S.D.),平均距離は33.4±12.5km,平均速度は0.46±0.21BL/sであった。
  受信機の結果から季節別の分布は,春季(5,6月);中流域から河口域,夏季(7,8月);中上流域から中流域,秋季(9,10,11月);下流域から河口域,であった。また,下流域の水温が急激に上昇した際た,中流域まで遡上した個体も見られ,その移動距離は最大約13kmに及んだ。さらに,季節間だけではなく昼,夜間においても行動の傾向が異なっており,春季では夜間の1時間あたりの受信数が昼間の受信数の約2倍あり,夏季では日出,日入時刻の受信数が多かった。
  以上より,産卵直後の降下行動においては,イトウは好条件の生息場所の確保を目的に降下していると推察された。季節移動には,水温と餌環境が影響していることが推察される。また,比較的短期での行動は,昼夜,潮汐,降雨などの影響を受けていることも考えられた。
  日本学術振興会, 萌芽研究, 北海道大学, 18651110
• Estimation of juvenile southern bluefin tuna migration using an acoustic telemetry system
  Grants-in-Aid for Scientific Research
  2004 - 2006
  MIYASHITA Kazushi, WATANUKI Yutaka, KAWABE Ryo
  In the study period, we made a significant progress on mainly two issues. The summery of results are described below.
  1. Environmentally-based distribution
  When the influence of the Leeuwin Current was strong (2004-05),warm water (approx. 19.5℃) was widely distributed in the survey area. In this season, many juvenile southern bluefin tuna (SBT) were intensively distributed over the surroundings of inshore seamounts (92% of all appearances).Whereas in 2005-06 when the influence of the current was weak in the survey area, inflow of cold water from sub-Antarctic could be considered, and many warm and cold water masses existed on the continental shelf. Therefore, SBT juveniles were not concentrated near the seamounts, but they tended to occur around the water masses. From the above and past studies, it was suggested that the distribution of SBT juveniles was greatly influenced by the distribution of. Pelagic prey species such as Sardinops sagax and juvenile Scomber australasicus, Which are related to the changes of ocean environment.
  2. Size-dependent distribution
  In all the years, large SBT tended to be received by coastal receivers. When 2-year-and 1-year-old SBT were simultaneously distributed over the same area (2003-03 and 2003-04), 2-year-olds occurred more inshore, and when 2-year-olds were not distributed (2004-05 and 2005-06), large 1-year-olds (> 50 cm) appeared more inshore than small 1-year-olds (〓 50 cm).Especially in 2004-05, large 1-year-olds concentrated around inshore seamounts (97% of all appearances for large 1-year-olds, small 1-year-olds: 50%).For this reason, it was thought that juvenile SBT were performing size-dependent competition between individuals aiming the niche of the surroundings of inshore seamounts where many preys (Spratelloides robustus, Engraulis australis and etc.) are distributed
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 16255010
• 自然環境下におけるスケトウダラの遊泳姿勢角度の高精度計測手法の開発
  科学研究費助成事業
  2004 - 2005
  宮下 和士, 綿貫 豊, 河邊 玲
  ターゲットストレングス(TS)は、計量魚群探知機やソナーでスケトウダラの資源量を見積もる際の最重要パラメータである。TSは、スケトウダラの遊泳姿勢角度により大きく変動するためその資源量推定を左右する。しかし、これまで技術的な困難さからスケトウダラの遊泳姿勢角度の計測はない。そこで本研究では、本種の現存量推定精度向上に資するために、加速度データロガーを用いて遊泳姿勢角度を直接計測した。実験は2005年3月16-27に実験水槽内でおこなった。スケトウダラ6個体(平均体長:45.3cm)の腹腔内にデータロガーを装着し約3日間にわたり遊泳姿勢を測定した。結果、遊泳中の個体ごとの平均遊泳姿勢は-6.2度から3.75度(-が長軸方向下向き、+が長軸方向上向き)であり、ほぼ水平を示した。最大遊泳姿勢角度は-75.4度から-66.9度であった。また、夜間に比べて昼間にやや上向き角(平均角度差:7.2度)であった。以上の結果より、閉鎖空間である水槽で得られたものであるが、本手法を用いた遊泳姿勢角計測の有効性が示された。今後、回収方法を考案し、フィールドでの実証実験を重ねることにより、本種の自然状態での遊泳姿勢角推定が可能となることが予想される。
  日本学術振興会, 萌芽研究, 北海道大学, 16658076
• VISUALIZATION AND QUANTIFICATION OF MARINE BIOLOGICAL RESOURCES USING BI-PLANE SCANNING SONAR
  Grants-in-Aid for Scientific Research
  2003 - 2005
  IIDA Kohji, YOSHIMURA Yasuo, MUKAI Tohru, MIYASHITA Kazushi
  The scanning sonar can detect fish school much wider area in the water compared to an echo sounder. The purpose of this study is to develop the new generation quantitative scanning sonar to measure the shape, the volume and the density of the fish school for fisheries survey.
  1)The quantitative sonar we developed was installed on the fishing boat in Norway and we measured the fish school volume with purse seine fishing for herring and blue whiting. The new sonar was also tested in domestic fishing ground with purse seine fishing for mackerel, squid and yellow tail. Fish schools were detected more than 3,000 meters far from the boat, and the good linear relationship between estimated volume and the catch were found.
  2)To estimate density of fish school by echo integration method, the target strength in side aspect is necessary. We measured the 3-dimensional target strength of anchovy in sonar frequencies. The target strength in side aspect agreed well to the TS in dorsal aspect, and it showed the "8" figured directional pattern.
  3)To calculate fish number from the fish school volume, the specific occupation volume by a single fish (Tv) is required. We estimated Tv of walleye pollock dividing the volume backscattering strength (Sv) of fish school by the target strength of fish. Results showed that the Tv is proportional to the 2.6th power of the body length.
  4)Using the successive multiple sonar images of fish school obtained by the vertical mode, the three dimensional shape of fish school was reconstructed by 3D image processing techniques.
  5)Results of the study were presented at fisheries and acoustics symposiums. Some of them were applied for domestic and international patents.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), HOKKAIDO UNIVERSITY, 15208017
• Study on acoustic estimation of myctophid fishes biomass
  Grants-in-Aid for Scientific Research
  2002 - 2003
  AOKI Ichiro, MIYASHITA Kazushi
  1.a soft-X ray system was used to observe swimbladders of 14 species of myctophids. The shape and size of the swimbladder varied with developmental stage. In most species the sswimbladders varied with developmental stage. In most species the swimbladders did not grow in proportion with body length, and in a few species the swimbladders began to degenerate at a certain life stage.
  2.the body density ration (g) ranged from 1.003 to 1.020 for 5 species examined except Myctophum asperum. Especially, two species of Stenobranchius had a low density ratio (1.004) similar to sea water density. The sound speed ratio (h) of fish body to sea water changed depending on temperature. Therefore, considering temperature in habitat of fish, the sound speed rations were estimated 1.032-1.039 for Stenobranchius leucopsarus, 1.024-1.036 for Notoscopelus japonicus, and 1.012-1.024 for Myctophum asperum.
  3.based on the morphological measurement and values of g and h obtained above, the theoretical target strength (TS) was calculated using PSM and DCM scattering models. For fish with swimbladder, though there was a 2-5 dB difference in TS between the two models, measured TS in a tank was in accord with PSM. On the other hand, TS patterns of swimbladder-less fish calculated by PSM and DCM were similar, and accord with measured TS patterns in the broadside region.
  4.TS was less dependent on the tilt angle at frequencies of 38-200kHz, because the swimbladders of myctophids were spherical and very small. Normalized TS (TScm) was consistently below -70dB in this frequency range. TS of myctophids was not in proportion to square of body length because of irregular growth of swimbladders.
  5,8 million tons with density of 50-100gm^<-2>. Similarly, biomass of Diaphus theta was estimated 75 thousand tons with mean density of 35gm^<-2>.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), The University of Tokyo, 14560142
• 計量魚探・定量採集具を用いたオキアミ類の分布構造の解明および資源量推定法の開発
  科学研究費助成事業
  2000 - 2001
  宮下 和士
  本申請研究の目的は、道東・三陸沿岸域において濃密に分布するオキアミ類に対し、その3次元分布構造の解明と資源量推定法の開発を行うことである。申請年度内において、以下の研究事項に従事し、結果を得た。
  海洋水産資源開発センターによるスケトウダラ・オキアミ資源調査(北海道太平洋沿岸域、2001年6月10〜7月30日、2002年1月6日〜2月4日)において、2周波(38kHz、120kHz)計量魚探による音響情報、CTD、X-CTDによる海洋環境情報、ボンゴネットによる生物採集情報を収集した。
  次に、調査で得られた音響情報および生物情報より、音響周波数特性を利用したオキアミ類のサイズ別判別を試みた。生物情報より本調査海域におけるオキアミ類の体長を等価球半径で標準化した結果、そのサイズは、小(0.027mm≦等価球半径≦0.075mm)、中(1.72mm≦等価球半径≦2.47mm)、大(3.47mm≦等価球半径≦3.76mm)3階級に分別された。得られたサイズ階級情報より、音響周波数特性を利用したオキアミサイズ判別を行った結果、それぞれのサイズ階級におけるオキアミの定量的な音響情報の抽出が可能となった。また、抽出したオキアミの音響情報と、水深情報、水温情報等をGIS技術を用いて重ね合わせることにも成功した。
  今後はこれらの結果をもとに、3次元表現、4次元表現の技術の高度化を目指すと同時に、スケトウダラ等のオキアミを餌としている生物の情報とのリンクを図る予定である。
  日本学術振興会, 奨励研究(A), 北海道大学, 12760125
• Quantitative Spatial Visualization of Aquatic Living Resources　　　　　　　　　　　　　　　
  1998
  Competitive research funding
• スマート水産業に関する研究