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Marine Ecology Progress Series

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MEPS 662:125-138 (2021)  -  DOI: https://doi.org/10.3354/meps13625

Differences in the reproductive traits of Pacific bluefin tuna Thunnus orientalis among three fishing grounds in the Sea of Japan

Hiroshi Ashida1,*, Yumi Okochi1,2, Seiji Ohshimo3, Takuya Sato1, Yukio Ishihara4, Shuuyo Watanabe4, Ko Fujioka1, Seishiro Furukawa5, Tomonori Kuwahara2, Yuko Hiraoka1, Yosuke Tanaka1

1Shimizu Field station, Fisheries Recourses Institute, Japan Fisheries Research and Education Agency, Shimizu, Shizuoka 424-8633, Japan
2Environmental management unit, JAPAN NUS Co. Ltd, Shinjuku-ku, Tokyo, 160-0023 Japan
3Nagasaki Field station, Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Nagasaki, Nagasaki 851-2213, Japan
4Tottori Prefectural Fisheries Experimental Station, Sakai-Minato, Tottori 684-0046, Japan
5Niigata Field station, Fisheries Resources Institute, Fisheries Research and Education Agency, Niigata, Niigata 961-8121, Japan
*Corresponding author:

ABSTRACT: Differences in the reproductive traits of Pacific bluefin tuna Thunnus orientalis (PBF) in the Sea of Japan (SOJ) were investigated to evaluate the reproductive potential in 3 fishing grounds (i.e. northern, central and southern areas). The size distribution of PBF differed among the fishing grounds, with smaller fish (100-130 cm in fork length, FL) being caught in the central and northern areas of the SOJ. Spawning-capable females were found at sea surface temperatures (SSTs) between 17 and 25°C, with most SSTs >21°C. Seasonal changes in SST differed among the fishing grounds, and the period when SST exceeded 21°C differed in each fishing ground. Spawning-capable females were found at different times among the fishing grounds, and were observed throughout the fishing season in the southern area of the SOJ. The mean ± SD relative batch fecundity was estimated to be 69.8 ± 45.3 and 92.7 ± 43.1 oocytes g-1 in the central and southern areas of the SOJ, respectively. The total spawning fraction was 0.2, 0.38 and 0.73 in the northern, central and southern areas of the SOJ, respectively. SST and FL were positively correlated with the batch fecundity. In addition, FL, SST and location affected the probability of occurrence of spawning-capable fish among mature fish. Therefore, the difference in the observed reproductive potential of PBF among fishing grounds in the SOJ can be linked to the differences in seasonal increases in SST and the size distribution of adult fish.


KEY WORDS: Atresia · Batch fecundity · Geographical variation · Postovulatory follicles · Reproductive traits · Spawning fraction


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Cite this article as: Ashida H, Okochi Y, Ohshimo S, Sato T and others (2021) Differences in the reproductive traits of Pacific bluefin tuna Thunnus orientalis among three fishing grounds in the Sea of Japan. Mar Ecol Prog Ser 662:125-138. https://doi.org/10.3354/meps13625

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