碩士 / 國立臺灣海洋大學 / 環境生物與漁業科學學系 / 107 / Lutjanus argentimaculatus, commonly known as mangrove snapper, is one of the high economic fish species in Taiwan and is also a key target species for stock enhancement in recent years. However few researches have focused on the fishery biology of this species in Taiwan coastal water. To estimate the growth parameters and to understand whether geological differences exist, current study collected specimens from northeastern and western for comparison. Sampling time was from January 2017 to November 2018 for each month. A total of 336 fish was collected, including 117 females, 77 males, 93 sex undiffenrtiation ,and 49 with undeveloped gonad. Overall, female to male ratio is 0.60, and the chi-square test showed no significant difference between sex samples. The total length (TL) ranged from 122 to 972 mm and the total weight (TW) ranged from 34 to 12796 g. The relationship between TL and TW showed significant differences between sexes, but not significant differences between sampling areas.
The otolith sections were used for age determination. Marginal increment ratios (MIR) verified the otolith rings formed annually, and the formation of translucent zone began from May. The maximum age of female and male fish was 42 and 29 years old, respectively. Von Bertalanffy growth equation (VBGE) was used for growth parameters estimating of mangrove snapper, and no significant difference were found between the sexes, so the growth parameters of sex-pooled samples are L∞= 877 mm, k=0.18, and t0=−1.48. There is no significant difference in the growth equation between sex in each sampling area. However, there are significant differences between sampling areas, indicating that the growth patterns of the mangrove snapper in the surrounding waters of Taiwan are slightly different, and should be put into consideration when applying on fishery management.
According to the reproductively biology analysis, the results show that the Gonadosomatic index (GSI) and the group maturity rate both were higher from April to September, speculated to be its reproductive season peaking at May to June and September. The length at 50% maturity of female and male fish is 606 mm and 475 mm, respectively. And the age at 50% maturity is 4.5 years and 2.5 years old, which indicating it is a gonochoristic species. According to the results, male matured earlier than female. The average number of total fecundity of the mangrove snapper was 2,867,167 ± 430,916, and the relative total fecundity was 398 ± 292 eggs/g. Due to no occurences of the hydrated oocytes stage egs sample, the eggs in migratory nucleus stage were counted. The number of batch fecundity was 122,905 ± 23,577, and the relative batch fecundity was 12 ± 11 eggs/g.
In conclusion, mangrove snapper in Taiwan waters showed varied growth parameter spatially, but same between sex. Therefore, the age and length at 50% maturity differed between sex, and male matured earlier. Present study showed the complete fishery biology information of wild mangrove snapper population in Taiwan, and can used as the background information for future research on fishery management, environmental change and anthropogenic influences.
| Identifer | oai:union.ndltd.org:TW/107NTOU5451021 |
| Date | January 2019 |
| Creators | Yeh, Yun-Ting, 葉芸婷 |
| Contributors | Wang, Chia-Hui, 王佳惠 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 108 |
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