Biosphere Sci. 55 1-6 (2016) 耳石 Sr:Ca 比によって推定した利根川産大型ヤマメの回遊履歴 1) 2) 3) 1) * 1) 739 8528 1-4-4 2) 375-0011 3) 371-0036 13 要旨 8 Sr:Ca 3 5 4 243km キーワード : Sr:Ca 緒 言 Oncorhynchus masou masou 1980 2014 4 2014 1960 2,000t 2005 500t 2008 1999 2006 2008 2008 1 2 2014 3 9 11 2014 Kasugai et al. 2014 1 5 322km 16,840km 2 2014 200km 2014 Sr:Ca Sr:Ca 材料および方法 供試魚の採集 32 54 cm 8 1999 2015 180 243km St.1 2016 9 12 *E-mail: umino@hiroshima-u.ac.jp
2 4 Table 1 #1 7 7 St. 1 3 4 8 St. 3 Fig. 1 #8 St. 4 2015 6 Sr:Ca 1985 1993 2000 2014 0.01g Sea of Japan Fig. 1. Map showing sampling stations (St. 1-4). Table 1. Summary of specimens Oncorhynchus masou masou used for Sr:Ca analyses. Fish ID Sampling site Distance from the Tonegawa River mouth (km) Sampling date Total length (cm) Body weight (kg) Migration patterns inferred from Sr:Ca ratio # 1 St. 3 243 June 2010 32 0.5 Non-anadromous # 2 St. 1 211 August 1999 44 1.0 Anadromous # 3 St. 3 243 April 2011 35 0.6 Non-anadromous # 4 St. 2 221 May 2010 45 1.2 Non-anadromous # 5 St. 3 243 June 2012 54 1.6 Anadromous # 6 St. 1 211 July 2013 40 0.6 Non-anadromous # 7 St. 1 211 July 2015 51 1.5 Anadromous # 8 St. 4 180 June 2015 38 0.6 Non-anadromous 耳石 Sr:Ca 比分析 8 Epofix Stuers 220 2400 3 m Sr:Ca JXA-8200 2001 1 10 5 m 15Kv 10nA X % SrTiO 3 CaSiO 3 10 3 Sr:Ca
3 結果および考察 8 Sr:Ca Fig. 2 Sr:Ca 2 #1 3 4 6 8 5 Sr:Ca 2 1200 1500 m Sr:Ca 4 #2 5 7 3 Fig. 2. Changes in the Sr:Ca ratio between the core and the edge of the sagittal otolith of Oncorhynchus masou masou at 180-243 km upstream in the Tonegawa River.
4 Oncorhynchus masou ishikawae Sr:Ca 1 2 3 4 Arai and Tsukamoto 1998 2001 Ohji et al. 2007 2014 Kasugai et al., 2014 Sr:Ca 2 5 #1 3 4 6 8 Sr:Ca 3 #2 5 7 1999 2015 3 #2 5 7 5 #1 3 4 6 8 Stenopsyche sp. Baetiella sp. Cercion sp. Table 2 Phoxinus sp. 1980 2000 2004 2014 2014 Stenopsyche marmorata 2008 2004 Phoxinus lagowski steindachneri 1998 3 2014 2014 3 211 243km 200km #5 3 2 2 2015 2015 Table 2. Stomach contents of five Oncorhynchus masou masou. Stomach contents (species) Weight (g) # 1 # 3 # 4 # 6 # 8 Trichoptera (Stenopsyche sp.) 0.12 0.93 Ephemeroptera (Baetiella sp.) 0.03 Odonata (Cercion sp.) 0.18 Oligochaeta (species unknown) 0.38 0.31 Fish (Phoxinus sp.) 10.68 謝 辞 Sr:Ca
5 引用文献 2014 20 22-28 Arai, T., Tsukamoto, K., 1998. Application of otolith Sr : Ca ratios to estimate the migratory history of masu salmon, Oncorhynchus masou. Ichthyological Research. 45: 309-313. 2006 8 233-244 1998 42-45 1980 1 8 5-15 1993 212-223 1985 53-57 2014 267 pp Kasugai, K., Hayano, H., Mano, S., Watanabe, T., Yoshikawa, T., Saito, M., Wakimoto R., Sugiwaka, K., 2014. Preliminary study of migration history estimated from otolith Sr:Ca ratios of masu salmon (Oncorhynchus masou) in Lake Kussharo. Ichthyological Research. 61: 178-182. 2014 186 pp 1980 34 1-6 2000 244 pp 2008 22-65 Ohji M., Arai T., Miyazaki N., 2007. Comparison of organotin accumulation in the masu salmon Oncorhynchus masou accompanying migratory histories. Estuarine, Coastal and Shelf Science. 72: 721-731. 2004 51 123-134 2004 10 3-13 2008 1980 56:137-138 2015 Cottus sp middle-egg type 54 7-12 1999 47 115-118 2008 14 1-10 2001 67 647-657 2015 Sr:Ca 18 147-154 2000 Oncorhynchus masou masou 48 615-622 2008 153-157
6 Insight into the migratory history using otolith Sr : Ca ratio of the anadromous masu salmon Oncorhynchus masou masou from the Tonegawa River Atsushi Tsuyuki 1), Kouken Sorimachi 2), Hajime Arai 3), Tetsuya Umino 1) 1) Graduate School of Biosphere Science, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan 2) Okanogou, Fujioka, Gunma 375-0011, Japan 3) Gunma Prefectural Fisheries Experimental Station, 13 Shikishimacho, Maebashi, Gunma 371-0036, Japan Summary The migratory histories of Oncorhynchus masou masou in the Tonegawa River were evaluated from the ontogenetic changes in otolith Sr:Ca ratios. We sampled 8 fish at 180-243 km upstream from the river mouth. Three fish were categorized as anadromous whereas five individual were categorized as nonanadromous life mode with the constantly low Sr:Ca ratios. Intraspecific variation in the migration modes recorded for O. masou masou suggest a plasticity strategy for anadromous behaviors. Key words: Anadromous, Migratory history, Oncorhynchus masou masou, Sr/Ca ratios, Tonegawa River