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Vol. 44 No. 4, 2005
Reproductive Biology of the Blue Sprat Spratelloides gracilis in the Waters around Penghu, Central Taiwan Strait
Jinn-Sheng Weng1, Kwang-Ming Liu2,*, Sin-Che Lee3, and Wann-Sheng Tsai4
1Coastal
and Offshore Research Center, Taiwan Fisheries Research Institute, No.
1-1 North 1st Road, Chienchen Fishing Port, Kaohsiung, Taiwan 806
2Institute of Marine Resource Management, National Taiwan Ocean University, No. 2 Pei-Ning Road, Keelung, Taiwan 202
3Department of Biology, Tunghai University, No. 181 Chungkan Road, Sec. 3, Taichung, Taiwan 407
4Pescadores Marine Biology Center, Taiwan Fisheries Research Institute, Makung, Penghu, Taiwan 880
Jinn-Sheng Weng, Kwang-Ming Liu, Sin-Che Lee, and Wann-Sheng Tsai (2005) The reproductive biology of the blue sprat, Spratelloides gracilis,
is described based on 7737 specimens collected from Mar. 2001 to Feb.
2003 in the waters off Penghu (the Pescadores), off the southwestern
coast of Taiwan in the central Taiwan Strait. The spawning season was
estimated to be from Feb. to Sept. based on progressive changes in the
size of the ovaries, histological examination of the ovaries, oocyte
diameter measurements, and gonadosomatic index calculations. The body
weight (BW)-fork length (FL) relationship was estimated to be BW = 6.06
x 10-6 FL3.087 for both sexes combined (n = 4042, p
< 0.05). Eight stages of oocyte development were determined based on
the histological examination. Ovarian development could be divided into
immature, maturing, mature, and spent stages. Mean fecundity of this
species was 2606 ± 1678 eggs, and mean batch fecundity was 1204 ± 714
eggs. The sex ratio (0.45) significantly differed from 0.5 (p < 0.05). Relationships of fecundity (F) and batch fecundity (BF) with fork length (FL) were estimated to be F = 0.0002 FL3.841 (r2 = 0.58, n = 62, p < 0.05) and BF = 0.001 FL3.806 (r2 = 0.82, n = 60, p
< 0.05), respectively. Size at 1st maturity for females estimated
from the logistic model was 54 mm FL, which corresponded to an age of
120 d old.
Key words: Spratelloides gracilis, Blue sprat, Reproductive biology, Southwestern Taiwan.
*Correspondence: Tel: 886-2-2462-2192 ext. 5018. Fax: 886-2-2462-0291. E-mail: kmliu@mail.ntou.edu.tw
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