Migratory life history of icefishes (Teleost: Salangidae) revealed by otolith daily increment and Sr/Ca ratio

• Main Authors: Chien-Yu Chen, 陳建宇
• Other Authors: Jen-Chieh Shiao
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/02525536972569316466

碩士 === 國立臺灣大學 === 海洋研究所 === 99 === Icefishes, belonging to Salangidae, consist of five genera, 20 species (Liou et al., 2000), which mainly distribute in the lakes, rivers, estuaries, and coastal area in the East China. This research studies their life history and migratory patterns by analyzing otolith microstructure and microchemistry. The otoliths of most Salangidae populations grow fastest in spring and early summer, and the growth rate gradually decrease and stabilize in late summer and early autumn. These results indicate that the increment of otolith is influenced by seasons and temperature. But the change of feeding niches may also affect otolith growth as reported in previous studies. Neosalanx tangkahkeii spawned in spring, Salanx ariakensis in winter, Neosalanx anderssoni during the late spring to early summer, and Protosalanx chinensis during the late winter to early spring based on the back calculation from daily growth increment. The otolith Sr/Ca ratio of icefishes is positively correlated with environmental salinity (R = 0.93, p < 0.05). The maximum value of otolith Sr/Ca for the freshwater population was 5.17‰ while the minimum value for the seawater population was 14.38‰. The values between 5.17‰ and 14.38‰ were defined as the brackish water environments. Chronological profile of otolith Sr/Ca ratio suggested four migratory types: (1) freshwater-restricted type, e.g. Neosalanx tangkahkeii in Taihu Lake; (2) seawater type, e.g. Neosalanx tangkahkeii in the Pearl River estuary and Neosalanx anderssoni in Qinhuangdao; (3) Anadromous type, e.g. Salanx ariakenesis in Yangtze River estuary; (4) freshwater-unbound type, e.g. Protosalanx chinensis in Yangtze River estuary and the Taihu Lake.