The occurrence and run timing of naturally spawning chum salmon in northern Japan
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Abstract Since the late 20th century, the biomass of Pacific salmon Oncorhynchus spp. has increased. Hokkaido, northern Japan, is one of the main areas of chum salmon O. keta production in the North Pacific and intensive hatchery programs support the recent high abundance. However, proper management of naturally spawning populations is necessary to conserve healthy stocks of this species. In 2008, we started a program to assess the naturally spawning chum salmon populations in Hokkaido. Of the total of approximately 1,500 rivers in Hokkaido, 238 rivers with lengths of longer than 8 km (excluding those rivers used for hatchery broodstock collection) were surveyed in 2008 and 2009. The number of non-enhanced rivers found to contain naturally reproducing chum salmon was 59 (31.4% of surveyed rivers) and 50 (37.6% of surveyed rivers) rivers in 2008 and 2009, respectively. Including the rivers where hatchery broodstock were collected and rivers shorter than 8 km that contain naturally spawning chum salmon, chum salmon ascended at least 191 and 175 rivers in Hokkaido in 2008 and 2009, respectively. Repeated foot surveys indicated that the run timings of naturally spawning chum salmon may be affected by coastal commercial fisheries. This study showed that naturally spawning chum salmon remain in many rivers in Hokkaido where hatchery programs have been intensively conducted.




  • Content Type Journal Article
  • Pages 1-10
  • DOI 10.1007/s10641-011-9872-5
  • Authors
    • Yasuyuki Miyakoshi, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Hirokazu Urabe, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Hayato Saneyoshi, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Tomoya Aoyama, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Hiroyuki Sakamoto, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Daisei Ando, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Kiyoshi Kasugai, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan
    • Yoshio Mishima, Graduate School of Agriculture, Hokkaido University, Kita 9-jyo Nishi 9-chome, Kita-ku, Sapporo, Hokkaido 060–8589, Japan
    • Masayuki Takada, Institute of Environmental Sciences, Hokkaido Research Organization, Kita 19-jyo Nishi 12-chome, Kita-ku, Sapporo, Hokkaido 060–0819, Japan
    • Mitsuhiro Nagata, Salmon and Freshwater Fisheries Research Institute, Hokkaido Research Organization, 3-373 Kita-Kashiwagi, Eniwa, Hokkaido 061–1433, Japan





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