Fisheries Science

, Volume 77, Issue 2, pp 161–167 | Cite as

Swimming angle and target strength of larval Japanese anchovy (Engraulis japonicus)

  • Yusuke Ito
  • Hiroki Yasuma
  • Reiji Masuda
  • Kenji Minami
  • Ryuichi Matsukura
  • Saho Morioka
  • Kazushi Miyashita
Original Article Fisheries


The swimming angle of larval Japanese anchovy (Engraulis japonicus) was measured in a tank, and target strength (TS) was calculated using a theoretical scattering model. The mean swimming angle was 12.8° (SD ±22.1). Increased speeds of flow led to increased mean swimming angles. The mean swimming angle at flow of 5 cm s−1 was higher than at other speeds. TS values were estimated using a distorted-wave Born approximation model for two cases. Average values were 1–3 cm s−1 (11.5° ± 22.1) and 5 cm s−1 (16.6° ± 21.7) for cases 1 and 2, respectively. For case 1, TS ranged from −92.0 to −74.7 dB with a mean of −79.4 dB at 120 kHz. For case 2, TS ranged from −92.2 to −75.2 dB with a mean of −79.9 dB. The mean TS in case 2 was lower than that in case 1, with the maximum difference being 1.0 dB at 120 kHz (standard length 22.0 mm). However, there were no significant differences between the regression lines of cases 1 and 2. Thus, changes in flow speed altered the swimming angle of larval Japanese anchovy, but had little influence on TS.


Larval Japanese anchovy Swimming angle Target strength 



We thank the captains and crew of Kanagasaki Maru No. 8 for their cooperation in collecting specimens. We also thank Yukio Ueta, Keisuke Mori Fisheries Research Institute, Tokushima Agriculture and the Forestry and Fisheries Technology Support Center for their support in collecting specimens. This study was supported in part by the Fisheries Agency of Japan under the project “Research and Development Projects for Application in Promoting New Policy of Agriculture Forestry and Fisheries.” We thank this institution for their support.


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Copyright information

© The Japanese Society of Fisheries Science 2011

Authors and Affiliations

  • Yusuke Ito
    • 1
  • Hiroki Yasuma
    • 2
  • Reiji Masuda
    • 3
  • Kenji Minami
    • 3
  • Ryuichi Matsukura
    • 4
  • Saho Morioka
    • 5
  • Kazushi Miyashita
    • 2
  1. 1.Laboratory of Marine Ecosystem Change Analysis, Graduate School of Environmental ScienceHokkaido UniversityHakodateJapan
  2. 2.Laboratory of Marine Ecosystem Change Analysis, Field Science Center for Northern BiosphereHokkaido UniversityHakodateJapan
  3. 3.Fisheries Research StationKyoto UniversityMaizuruJapan
  4. 4.National Research Institute of Fisheries Engineering, FRAKamisuJapan
  5. 5.Fisheries Research InstituteTokushima Agriculture, Forestry and Fisheries Technology Support CenterTokushimaJapan

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