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Vol. 45 No. 4, 2006
Spawning Frequency and Batch Fecundity of the Sailfish (Istiophorus platypterus)
(Istiophoridae) in Waters off Eastern Taiwan
Wei-Chuan
Chiang1,2, Chi-Lu Sun1,*, Su-Zan Yeh1, Wei-Cheng Su3, and Don-Chung Liu3
1Institute
of Oceanography, National Taiwan University, Taipei, Taiwan 106
2Present address: Eastern Marine Biology Research
Center of Fisheries Research Institute, Council of Agriculture,
Executive Yuan, Taitung, Taiwan 961
3Fisheries Research Institute, Council of Agriculture,
Executive Yuan, Keelung, Taiwan 202
Wei-Chuan
Chiang, Chi-Lu Sun, Su-Zan Yeh, Wei-Cheng Su, and Don-Chung Liu (2006) The
sailfish (Istiophorus platypterus)
(Istiophoridae) is widely distributed in tropical and temperate oceans
of the world. In Taiwan, sailfish are abundant from Apr. to Oct. (with
the peak abundance from May to July) and substantially contribute to
the economy of the east coast of Taiwan. In this study, we estimated
the spawning frequency and batch fecundity of female sailfish off
eastern Taiwan based on histological examinations of the ovaries of 246
sailfish collected at the Shinkang Fish Market in eastern Taiwan
between Jan. 1999 and Sept. 2000. The proportion of mature females with
ovaries containing postovulatory follicles was 0.53 on average during
the spawning season of Apr. to Sept., suggesting that on average, the
sailfish spawns every 1.89 d. Sailfish are multiple spawners with
asynchronous oocyte development. Batch fecundity for 18 females with
the presence of hydrated oocytes but without postovulatory follicles
yielded (0.2-2.48) x 106 eggs with an average of 1.3 x 106
eggs. The relationships between batch fecundity in millions (BF) versus round weight (RW, in kg) and lower jaw fork
length (LJFL, in cm) are BF = 0.0944 x RW - 1.3134 (r2 = 0.724) and BF = 5.46 x 10-5 LJFL6.283
(r2 = 0.667),
respectively.
Key words: Sailfish,
Spawning frequency, Batch fecundity, Postovulatory follicles, Hydrated
oocytes.
*Correspondence: Tel and Fax: 886-2-23629842.
E-mail:chilu@ntu.edu.tw
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