碩士 / 國立海洋大學 / 漁業科學學系 / 84 / The reproduction, age and growth, and food habits of the
pelagic thresher, Alopias pelagicus, in the northeastern
waters of Taiwnn were studied. A total of 831 (508
females and 323 males) specimens was collected from September
1993 through August 1995 at Nan Fan Ao fish market.
Oophagous embryos have been recorded and 2 embryos
were pupped per litter. The length at birth is 72~81 cm. Sex
ratio of embryos was estimated to be 1.04:1. Sizes at
maturity were 140~145 for both sexes. Since no fixed
pupping season, the gestation period of this species can not be
estimated in this study. The age and growth was estimated by
annulus counts of caudal vertebra. The annuli were
counted up to be 16 and 14 for female and male, respectively.
The monthly changes of the marginal increment indicated that
translucent and opague zones on vertebral centra were
formed once a year between June and July. The mean square error
and coefficient of determination showed that the von Bertalanffy
growth equation estimated from observed length had a
better fit than that from back-calculated length. The
parameters of von Bertalanffy growth equation were as follows:
asymptotic length (L∞=189.8 cm PCL, growth coefficient
(k)=0.110/yr, age at zero length (t0)=-5.397 yr for female ;
and L∞=178.9 cm PCL, k=0.132/yr , t0=-4.704 yr for male.The
ages at maturity are 6.76~7.72 yr and 6.86~7.90 yr for
female and male, respectively. The oldest ages are 36.95
yr and 18.03 yr, respectively. Stomach content is comparatively
high and Scomber and Trichiurus were the dominant food items for
both sexes.
| Identifer | oai:union.ndltd.org:TW/084NTOU0451006 |
| Date | January 1996 |
| Creators | Liaw, Tai Hsiang, 廖泰祥 |
| Contributors | Kwang-Ming Liu, Che-Tsung Chen, 劉光明, 陳哲聰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 68 |
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