Sci.Rep.Hokkaido Fish.Res.Inst. Natural reproduction of chum salmon in Hashibetsu River, Hokkaido, Japan Short paper HAYATO SANEYOSHI 1, HILOSHI KAWAMULA 2, MAKOTO FUJIWARA 2, YASUYUKI MIYAKOSHI 2 and HIROKAZU URABE 2 1 Hokkaido Research Organization, Doto Research Branch, Salmon and Freshwater Fisheries Research Institute, Nakashibetsu, Hokkaido, 086 1164, 2 Hokkaido Research Organization, Salmon and Freshwater Fisheries Research Institute, Eniwa, Hokkaido, 061 1433, Japan Recent studies reported the presence of naturally reproduced chum salmon, Oncorhynchus keta, in Hokkaido, but scientific knowledge about that in Japan is still quite limited. To obtain basic biological traits about naturally reproduced chum salmon, we implemented a survey on natural spawning in fall 2010 and 2011 and resulting fry in spring 2011 and 2012 in Hashibetsu River, Northern Hokkaido, where enhancement has not been operated. Naturally spawning adults and fry were found in both the two study years, suggesting that the naturally spawning population was maintained in Hashibetsu River. Oncorhynchus keta 2011 2012 Fig. 1 47.0 km 2 17.6km 1995 1980 1984 100 140 1980 1985 1981 4 1983 87 1984 707 1988 3km Fig. 1 2 5km 500m 2 St.1 0.8km St.2 4km 5km 1 Fig. 1 2011 St.2 St.3 A525 2015 8 10 Tel: 0153 72 6141. Fax: 0153 72 5188. E mail: saneyoshi hayato@hro.or.jp
Map showing the location of Hashibetsu River and study site. Solid squares indicate hatcheries. Solid circle indicates study site for fry collection. St.1, St.2 and St.3 indicate foot survey reaches for escapements. 2011 2010 9 10 2011 8 9 10 40 m Fig. 1 2011 4 5 1 3 2012 3 5 1 Smith Root 2 5 70 100 2010 9 28 2 1 10 304 9 St.1 St.3 26 Table 1 2011 8 Number of live chum salmon, carcasses observed, and spawning redds of chum salmon in Hashibetsu River in 2010 and 2011.
9 2 229 9 38 10 3 60 11 2 5 Table 1 2011 9 38 23 10 St.1 4 27 9 4 3 13 5 20 87 10 4 3 75 5 1 25 Fig. 3 9 Fig. 2 4 5 Fig. 3 4 5 Kruskal Wallis test; P > 0.05 2011 4 4 3.6 4.0 Fig. 4 2012 3 4 1.0 4.2 Fig. 4 2011 4 12 35.7mm 34.0 38.0mm 0.3 g 0.2 0.3g 4 15 36.3mm 33.6 37.6mm 0.3g 0.2 0.3g 2012 3 35.4mm 34.3 36.9mm 0.3g 0.2 0.3g 4 35.2 Age composition of chum salmon captured in Hashibetsu, Shokanbetsu, and Nobusha Rivers in 2011. Fish were sampled by foot survey in Hashibetsu River and were sampled by weir for broodstock collection in Shokanbetsu and Nobusha Rivers. Fork lengths of age 4 and age 5 female chum salmon captured in Hashibetsu, Shokanbetsu, and Nobusha Rivers in 2011. Numbers indicate sample sizes. Vertical bars indicate standard deviations.
Number of chum salmon fry captured bars and water temperature observed circles in spring 2011 and 2012. mm 34.0 36.1mm 0.2g 0.2 0.3g 4 32.4mm 29.3 34.9mm 0.2g 0.2 0.3g Table 3 2011 23.1%,2012 50 100 2011 0.9 1.3%,2012 0.2 0.3 Table 2 2010 2011 2011 2008 2009 2011 2012 2008 Number, size and stomach content index SCI of chum salmon fry captured in Hashibetsu River in 2011and 2012.
9 10 2011 2009 9 11 Miyakoshi et al., 2012 2010 9 9 2011 9 2010 10 2010 2011 10 2010 10 2011 10 2011 9 St.2 117 9 2 35 mm 0.2 0.3g 49.3mm 1.1g 0.3g 2011 1986 38 50mm 2011 0.9 1.3 2012 0.2 0.3 3 4 4 2 21 2011; 3 6. Oncorhynchus keta Walbaum 1986; 40: 31 92. 2011; 80: 51 64. Miyakoshi Y, Urabe H, Saneyoshi H, Aoyama T, Sakamoto H, Ando D, Kasugai K, Mishima Y, Takada M, Nagata M. The occurrence and run timing of naturally spawning chum salmon in northern Japan. Environ. Biol. Fish. 2012; 94: 197 206. 10 SALMON 2012; 6: 22 25. 48 60 1988; 472pp. 1995; 306pp.