Sci.Rep.Hokkaido Fish.Res.Inst. Age determination of Japanese flounder Paralichthys olivaceus, caught from Ishikari Bay, using cross sections of otoliths NOBORU HOSHINO Central Fisheries Research Institute, Hokkaido Research Organization, Yoichi, Hokkaido 046 8555, Japan The age of Japanese flounders Paralichthys olivaceus caught using commercial gill nets from Ishikari Bay in the Sea of Japan was determined using cross sections of sagittal otoliths. It was possible to determine individual age by counting the fine growth increments formed on the otolith cross section in the spawning season July. The age of Japanese flounder landed to the port of Yoichi since 2005 ranged from 1 to 9 years, with the highest frequency being 2 years. This result suggests that the growth variation among individuals or year classes is significantly large. In the class with total length >550mm, the frequency of males was remarkably low, and females aged 3 9 constituted most of the class. Flounders caught in the feeding season November to December were younger than those caught in the spawning season June to July, and individuals aged above 6 years were not found. ALK Paralichthys olivaceus 500 1,000 Fig. 1 5 7 10 1235cm 35 45 cm 1996 220 2014 1 14 2015 VPA 2006 2015 20152006 Annual changes in the commercial catch of Japanese flounder in Hokkaido. 2004 2005 2014 A520 2015 8 10 Tel: 0135 23 8707. Fax: 0135 23 8709. E mail: hoshino noboru@hro.or.jp
2005 2014 Fig. 2 2 6 7 11 12 1 22013 Map showing the geographic locations referred to in the text. 20 Table 1 2004 2013 1mm 0.2 0.3mm 2005 2014 6 7 11 12 Summary of Japanese flounder samples used in this study
Fig.3 Fig. 3 2004 2004 2011 1 Fig. 32013 7 196mm 140 200mm 1 1997 8 1 6 7 1 2005 2014 1 9 Table 2 Fig. 42 2 350mm 1 350 375mm 1 33 164 375 425mm 2 425mm 3500mm 550mm 3 9 450mm 5 5 6 Table 2 2005 2014 Fig. 5 401 2480 2 4 3 5 1 260% 3 90 2 3 90 2004 2007 1 24 200462007 720083 6 2011 2 6 7 Fig.6 Fig.6 7 8 9 11 12Fig.6 19 600mm 600 mm 10 2012 11 3740 716 675mm 8 8 7 10
１ ２ 星野 昇 Fig.3 Cross sectioned otolith of Japanese flounder caught from Ishikari Bay. Arrows indicate the annual rings.
Age composition of Japanese flounder caught on the west coast of Ishikari Bay Relative age compositions for each total length class of Japanese flounder shipped to the port of Yoichi in 2005 to 2014. Closed and opened bar show the frequencies of males and females, respectively. Values in graphs indicate the age.
Age compositions of Japanese flounder caught on the west coast of Ishikari Bay. Cross sectioned otolith of the Japanese flounder caught on July 15, 2014. Closed arrows indicate the annual rings. 10 7 8 2005 2014 21 1 350mm 2 2 2 300mm 500mm 3 400mm 2 3 2011 2007 1994 300 500mm350 600mm2008 2004 350 600mm400 600 mm 2 4 300km 19949 10150 300m 2 3 4 100m 4 Age length key ALK Table 2 2005 ALK ALK ALK 2 ALK 2005 2015ALK
ALK 2004; 70 5 : 714 721. VPA Paralichthys olivaceus 2006; 72 5 : 839 849. 1.425 2015; 18 19. 10.1.125 2015; 142 149. 2006; 70 4 : 249 255. 1994; 56: 69 76. 26 2014 3 2015; 1420 1444. 1 1997; 9 24. 24 2014: 13 49. 2013; 79 3 : 383 393. 2008; 3: 1 5. 1994; 42 4 : 593 600. 26 2014 3 2015; 1472 1502. 2007; 18: 1 11. 2011; 7: 1 8.