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Basin-scale distribution pattern and biomass estimation of Japanese anchovy Engraulis japonicus in the western North Pacific |
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| Authors: | Hiroto Murase Atsushi Kawabata Hiroshi Kubota Masayasu Nakagami Kazuo Amakasu Koki Abe Kazushi Miyashita Yoshioki Oozeki |
| Institution: | 1. The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan 2. National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan 3. National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa, 236-8648, Japan 4. Hachinohe Station, Tohoku National Fisheries Research Institute, 25-259 Shimo-mekurakubo, Hachinohe, Aomori, 031-0841, Japan 5. Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo, 108-8477, Japan 6. National Research Institute of Fisheries Engineering, 7620-7 Hasaki, Kamisu, Ibaraki, 314-0408, Japan 7. Field Science Center for the Northern Biosphere, Hokkaido University, 3-1-1 Minato, Hakodate, Hokkaido, 041-8611, Japan |
| Abstract: | The distribution pattern and biomass of the Japanese anchovy Engraulis japonicus in the offshore region of the western North Pacific (north of 35°N and west of 170°E) were studied using a quantitative echosounder. This is the first attempt at such a study in this region. Data were collected in summer from 2004 to 2007. The biomass was estimated using data collected at 38?kHz. Species compositions in the backscatterings from pelagic fish were assigned based on the results of trawl hauls taking account of sea surface temperature (SST). Japanese anchovy tended to be high density to the west of 153°E and were distributed in an SST range of 9?C24?°C. Although the temporal and spatial coverage of the survey differed each year, at least 1.5?C3.4 million tons of Japanese anchovy were present in the survey area between 2004 and 2007. To take account of the spatial coverage of the survey each year, the most reliable biomass estimate for this region in the time period was 3.4 million tons (coefficient of variation?0.22). |
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