Title page for etd-0722118-091554


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URN etd-0722118-091554
Author Hsiao-Yuan Ni
Author's Email Address No Public.
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Department Department of Oceanography
Year 2017
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Reproductive biology of Chrysochir aureus and Otolithes ruber in the waters off southwestern Taiwan
Date of Defense 2018-07-30
Page Count 0
Keyword
  • spawning season
  • sexual maturity
  • sex ratio
  • croaker
  • multiple spawner
  • Abstract Reproductive variables (e.g., sex ratio, length and age at sexual maturity, spawning season) of commercially important fishes are frequently used for stock assessment and fisheries management purposes.This study reports the reproductive variables of two commercially important croakers, Chrysochir aureus and Otolithes ruber, in the waters off southwestern Taiwan. We collected a total of 519 C. aureus and 330 O. ruber specimens at fish markets in southwestern Taiwan from November 2012 to November 2017. For both croaker species, the results from measuring BW and L exhibited no significant differences in the BW-L relationships between males and females. The BW-L relationships was BW=0.0058TL3.184 (n=518, R2=0.99) for C. aureus and BW=0.0055TL3.206 (n=328, R2=0.98) for O. ruber. There was only a significant difference in sex ratio among the O. ruber samples in favor of females. The length estimated for 50% of sexually mature C. aureus females was 26.3 cm, which was greater than the length for sexually mature O. ruber females (21.8 cm). The age estimated for 50% of the C. aureus females was 8.6 months earlier than the time interval for the O. ruber females, which was 11.2 months. For both species, the size at 50% sexually maturation of males was smaller than females. The length estimated for 50% of sexually mature C. aureus males and O. ruber males were 21.0 cm and 19.9 cm, respectively. The histological examination results suggest that both species are multiple spawners and have dissimilar spawning seasons. The C. aureus primarily spawn from July to December, whereas the O. ruber primarily spawn from April to July. The mean batch fecundity (±SD) and relative mean batch fecundity (±SD) for C. aureus were 141,763±26,750 eggs/individual and 328±97 (eggs/ovary-free body weight), while for O. ruber were 213,217 eggs/individual and 704 (eggs/ovary-free body weight). Besides banning trawling fisheries in 3 nautical miles, the author also suggests regulating the gill net usage during the spawning seasons (May–July) around the spawning ground, in order to insure the sustainable resources use of C. aureus and O. ruber.
    Advisory Committee
  • Wann-Duen Chiou - chair
  • Yih-Yia Liao - co-chair
  • Hsin-Ming Yeh - co-chair
  • Meng-Hsien Chen - advisor
  • Files
  • etd-0722118-091554.pdf
  • Indicate in-campus at 5 year and off-campus access at 5 year.
    Date of Submission 2018-08-22

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