頁籤選單縮合
題 名 | Comparison of the Early Life History of Anguilla reinhardtii and A. australis by Otolith Growth Increment |
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作 者 | Shaio,Jen-chieh; Tzeng,Wann-nian; CollinsAdrian; Lizuka,Yoshiyuki; | 書刊名 | 水產研究 |
卷 期 | 9:1/2 民90.12 |
頁 次 | 頁199-208 |
分類號 | 388.491 |
關鍵詞 | Anguilla australis; Anguilla reinhardtii; Otolith; Early life history; |
語 文 | 英文(English) |
英文摘要 | The glass eels of Anguilla reinhardtii and A. australis were collected from the estuaries of eastern Australia. Growth increments and Sr/Ca ratios in otoliths of the eels were examined. The age at metamorphosis from leptocephalus to glass eel stage was determined from where the increment width dramatically increased and the Sr/Ca ratio dropped. The pattern of temporal changes in otolith increment widths and Sr/Ca ratios were similar between species, however the duration of each ontogenetic stage was different. The mean age (± SD) of A. reinhardtii (n=119) at metamorphosis was 142.5 ± 12.3 d and at estuarine arrival was181.7 ± 16.5 d and was 173.7 ± 20.5 and 229.2 ± 29.4 d, respectively, for A. australis (n=150). The younger ages at estuarine arrival of A. reinhardtii suggest that the spawning grounds of this species lie closer to Australia than those of A. australis. In addition, the mean total length at recruitment of A. reinhardtii (49.4 ± 1.7 mm) was significantly smaller than for A. australis (54.6 ± 5.4 mm). However, the growth rates of A. reinhardtii (0.25 ± 0.02 mm/d) were significantly faster than for A. australis (0.23 ± 0.022 mm/d). The smaller sizes of A. reinhardtii at recruitment were likely due to the shorter marine larval period and faster growth rate compared with A. australis. The duration of the marine larval period and growth rate may be the principal factors in determining the geographical distribution of both A. reinhardtii, which tend to occur in tropical-subtropical waters, and A. australis, which dominate in more temperate waters. |
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