Nippon Suisan Gakkaishi 69 (4), 591-595 (2003)

Spawning season of the black sole Paraplagusia japonica in the Miyazaki coastal area of Japan

KAZUHIRO TASHIRO,1 KAZUO IWATA,2 MAKOTO ENDO,3TAKESHI TABARU4 AND MASAKO SATOH5

1Miyazaki Prefectural Advanced Fisheries Training School, Nichinan, Miyazaki 887-0002, 2Miyazaki Prefectural Fisheries Experimental Station, Miyazaki, Miyazaki 889-2162, 3Course of Aquatic Biosciences, Tokyo University of Fisheries, Minato, Tokyo 108-8477, 4Miyazaki Prefectural Sea-Farming Association, Nobeoka, Miyazaki 889-0322, 5Higashiusuki Agricultural and Forestry Promotion Bureau, Nobeoka, Miyazaki 882-0872, Japan

The spawning season of the female black sole Paraplagusia japonica was examined in the Miyazaki coastal area, Kyushu, Japan. A total of 456 fish (226 males and 230 females) were collected from a muddy sand area of less than 30m in depth during 1991, 1992, 1996 and 1997 using a small trawl net. Histological examination was made of the ovaries. The development form of oocytes in the ovaries was thought to belong to the “asynchronous oocyte development” type. From the seasonal changes in oocyte development and the gonad index, the spawning season in this region was assumed to occur multiple times during May and October, with the peak from June to August. The minimum size for maturation was 214mm (SL) and the size of fully matured fish was 240mm in length. The sex ratio was nearly 1:1 throughout the year.


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