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Vol. 47 No. 5, 2008
Hatching Period and Early-Stage Growth Rate of the Gold Estuarine Anchovy Stolephorus insularis in Taiwan as Inferred from Otolith Daily Growth Increments
Wann-Nian Tzeng1,2,*, Han Chu2, Kang-Ning Shen2, and Yu-Tzu Wang3
1Department of Life Science, College of Life Science, National Taiwan University, Taipei 106, Taiwan
2Institute of Fisheries Science, College of Life Science, National Taiwan University, Taipei 106, Taiwan
3Fisheries Research Institute, Council of Agriculture, Keelung 202, Taiwan
Wann-Nian Tzeng, Han Chu, Kang-Ning Shen, and Yu-Tzu Wang (2008) To
understand the reproductive strategies and recruitment dynamics of the
gold estuarine anchovy Stolephorus insularis in a subtropical area,
their seasonal abundance was investigated, and their hatching period
and growth rate were estimated from otolith daily growth
increments. Specimens were collected from the Tatu River estuary
on the west-central coast of Taiwan during 1997-1998. Juvenile
fish dominated the catch composition, suggesting that the estuary is a
nursery for newly recruited juveniles of S. insularis.
The distribution of hatching dates for anchovy in subtropical Taiwan
was similar to that of temperate zone fish, with a major spawning
season in spring and a minor spawning season in autumn. This
spawning strategy coincided with a new production cycle that was higher
in spring than in autumn. Mean standard lengths and ages of the
anchovy at recruitment were significantly larger for the autumn than
for the spring and summer cohorts (all p < 0.001), while the somatic and otolith growth rates were higher in spring than in summer and autumn (all p
< 0.001). Larval anchovy grew faster and reached their maximum
growth rate (inflexion point of the growth curve) earlier during summer
than during either spring or autumn. The growth rate after the
inflexion point was lower in autumn than in either spring or
summer. The reproductive and growth rate variability indicated
that the spring cohort is the major component of the stock and that the
autumn cohort is a minor supplement to overall recruitment.
Key words: Stolephorus insularis, Otolith, Spawning season, Growth rate, Production cycle.
*Correspondence: Tel: 886-2-33662887. Fax: 886-2-23639570. E-mail:wnt@ccms.ntu.edu.tw
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