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エチゼンクラゲNemopilema nomuraiの鉛直移動に関する研究
https://fra.repo.nii.ac.jp/records/2010951
https://fra.repo.nii.ac.jp/records/20109518fa091bb-ee82-4661-ad80-b854e13387aa
| 名前 / ファイル | ライセンス | アクション |
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fra_k_47_119.pdf (20.2 MB)
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| Item type | 紀要論文 / Departmental Bulletin Paper(1) | |||||
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| 公開日 | 2024-10-02 | |||||
| タイトル | ||||||
| タイトル | エチゼンクラゲNemopilema nomuraiの鉛直移動に関する研究 | |||||
| 言語 | ja | |||||
| タイトル | ||||||
| タイトル | Studies on vertical migration of the giant jellyfish Nemopilema nomurai | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | jpn | |||||
| キーワード | ||||||
| 言語 | en | |||||
| 主題Scheme | Other | |||||
| 主題 | Acoustic camera; Diel vertical migration; Pop-up archival transmiting tag; Ultrasonic pinger; Underwater video camera | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_6501 | |||||
| 資源タイプ | departmental bulletin paper | |||||
| アクセス権 | ||||||
| アクセス権 | open access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||
| 著者 |
本多, 直人
× 本多, 直人 |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | The giant jellyfish Nemopilema nomurai is a type of large Rhizostomeae outbreaking mainly in the coastal waters of China. So far, it was rare for this species to appear in the waters around Japan. But it has been frequent to appear in large quantities after 2002. Mass appeared N. nomurai in the fishing grounds of Japan caused serious damage to various local fisheries, such as damaging fishing nets and impeding fishing operations. To reduce the damage of fishery, countermeasures such as prediction of the migration path of N. nomurai and avoiding by-catch of the jellyfish have been studied. As basic knowledge for these studies, information on swimming behavior and distribution depth of N. nomurai is important. However, there was less historical findings about the distribution and behavioral ecology of N. nomurai. And furthermore, no method for investigating behavior and distribution of N. nomurai was established. Therefore, I worked on development of various methods to investigate behavioral ecology and elucidation of swimming behavior and distribution characteristics of N. nomurai using these methods in this study. First, the situation and countermeasures of fishery damage by N. nomurai were summarized, and clarified the problems in the survey to obtain the knowledge necessary for countermeasures in Chapter 1. In the conventional method, water tank experiments were commonly used to investigate behaviors of jellyfishes, and capture by plankton-net was common to investigate the distribution of jellyfishes. However, it was difficult to adapt such conventional research methods to the giant jellyfish. Therefore, newly devised methods to investigate the behavior and distribution of N. nomurai and the results of the investigations using these methods were described in this study. Since the basic swimming ability of N. nomurai was not clear so far, the swimming speed of N. nomurai which submerse in the sea were measured directly chasing by scuba diving in Chapter 2. The speed of the individual with a bell size of 0.6 to 1.6 m was 0.03 to 0.1 ms-1. So that relational expression, swimming speed (ms-1) = bell size (m) x 0.1/s, was obtained. The swimming speed of individual with a large bell size of 1 to 1.5 m appearing in the autumn season in the Japan Sea is about 0.1 to 0.15 ms-1. Therefore, although their swimming ability can proceed sufficiently against the weak flow in the sea, it is not enough to immigrate against the ocean current. A towed upward-looking underwater video camera system (TULCam) was developed for quantitative survey to investigate giant jellyfish distribution in Chapter 3. TULCam is able to observe jellyfish continuously and real-time with a video monitor on the boat connected through an optical fiber cable. Sea trials for the giant jellyfish observation by TULCam were carrie out on the Tsushima Strait in the Japan Sea. Area density of N nomurai which were observed by TULCam towed at a speed of 7 knots in a depth of 20 m were approximately 15 times more than visual counting on board. The depth and bell size of the jellyfish was estimated on the base of the towing speed and time duration in jellyfish image passing through the video monitor frame. Average in bell size of jellyfishes estimated by TULCam were almost the same as that of the jellyfishes caught by midwater trawl that was towed at the same area. In Chapter 4, the vertical distribution of N nomurai was investigated using a midwater trawl net with an underwater video camera and depth loggers. The cod end of this midwater trawl net was opened not to capture the giant jellyfish, because the giant jellyfish is too huge to capture and their body is easy to choke in the mesh of the net. Operations of the midwater trawl net made at approximately 100 km off the west coast of the Noto peninsula, in the Japan Sea. Almost all N nomurai were in the surface water shallower than approximately 40 m-depth, and the vertical distribution was depending on the time zone in the daytime. In Chapter 5, the swimming depth of 12 individuals N nomurai with bell diameters of 0.8 to 1.6 m were investigated using the electronic tags (pop-up archival transmitting tags and ultrasonic pingers). and the validity of the research method was evaluated. The N nomurai frequently showed vertical migration, with the swimming depth ranging from O to 176 m, the mean swimming depth of most individuals were less than 40 m. The swimming depths of N nomurai in the northern Japan Sea in the winter were mostly deeper than those of this species in the southern Japan Sea in the autumn. This result suggests that the range of the depths almost depends on the vertical structure of the ocean. Swimming depths during the nighttime were significantly deeper than those during the daytime. More specifically, during the daytime, the swimming depths in the afternoon tended to be shallower than those in the morning, while during the nighttime, the swimming depth after midnight was deeper than those before midnight. Most individuals were present at a water temperature of 14℃ or more at 95% time. In Chapter 6, an acoustic camera DIDSON that can be observed independently of illuminance and transparency in water was devised to investigate the distribution of N nomurai. At acoustic frequency of 1.8 MHz, it was possible to distinguish N nomurai in the shape up to a distance with 12 m, and the bell size of jellyfish could be measured from the acoustic images. At acoustic frequency of 1.1 MHz, it was possible to distinguish N nomurai as individuals up to a distance with 25 m. Frequency of 1.1 MHz. 20 m-visibility and vertically downward observation from boat towing was effective setting for N nomurai that was distributed in the Tsushima Strait in summer season. As a result of the survey, the same pattern as the diurnal vertical migration obtained by the electronic tags survey was confirmed. In Chapter 7, the effect of the oceanic structure on the vertical migration and distribution characteristics of N nomurai clarified in the above studies was investigated. The vertical distribution of N nomurai tended to depend on the vertical density and temperature structure of the seawater basically. In addition, by taking account of the factors of the diel vertical migration and swimming ability of the jellyfish, a model for estimating the distribution depth of N nomurai from the vertical water temperature, time and bell size of the jellyfish was devised. By this model, seasonal change of the vertical distribution of N nomurai in the offshore area of the Japan Sea could be reproduced almost exactly. And in Chapter 8, the survey methods developed in this study were compared with the other survey methods to summarize merits and demerits and clarify future issues. | |||||
| 言語 | en | |||||
| bibliographic_information |
ja : 水産研究・教育機構研究報告 en : Bulletin of Japan Fisheries Research and Education Agency 巻 47, p. 119-177, ページ数 59, 発行日 2018-03 |
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| 出版者 | ||||||
| 出版者 | 水産研究・教育機構 | |||||
| 言語 | ja | |||||
| 出版者 | ||||||
| 出版者 | Japan Fisheries Research and Education Agency | |||||
| 言語 | en | |||||
| item_10002_source_id_9 | ||||||
| 収録物識別子タイプ | PISSN | |||||
| 収録物識別子 | 2432-2830 | |||||
| item_10002_source_id_11 | ||||||
| 収録物識別子タイプ | NCID | |||||
| 収録物識別子 | AA12767505 | |||||
| item_10002_relation_11 | ||||||
| 識別子タイプ | EISSN | |||||
| 関連識別子 | 2758-3953 | |||||
| 情報源 | ||||||
| 識別子タイプ | Local | |||||
| 関連識別子 | fra_k_47_119 | |||||
| 関連サイト | ||||||
| 識別子タイプ | URI | |||||
| 関連識別子 | https://agriknowledge.affrc.go.jp/RN/2010922975 | |||||
| 関連名称 | 日本農学文献記事索引（AgriKnowledge） | |||||
| 出版タイプ | ||||||
| 出版タイプ | VoR | |||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||
