Recruitment and Hatching Dates of Grey Mullet (Mugil cephalus L.) Juveniles in the Tanshui Estuary of Northwest Taiwan

淡水河口烏魚稚魚之加入動態及孵化日

張至維(Chin-Wei Chang) ； 曾萬年(Wann-Nian Tzeng) ； 李英周(Ying-Chou Lee)

《Zoological Studies》 39卷2期 (2000/04) Pp. 99-106

摘要

本研究自1995年11月至1996年3月及1996年11月至1997年3月間，於臺灣西北部的淡水河口域採集烏魚的稚魚，並利用耳石上的成長輪推估其日齡、成長及孵化日。烏魚、稚魚、耳石成長輪的形成週期約為1天，可用來測定日齡。河口域的稚魚、族群由數個加入群所組成，體長範圍為17至39mm，日齡約為29至67天，成長率約為0.45 mmd^(-1)。由日齡逆算的孵化日為10月至2月，比外海洄游群的產卵期11月至1月還長。因此淡水河口域的烏魚、稚魚、可能來自本地及洄游產卵群，或者可能來自於不同產卵期的迴游族群。

關鍵字

烏魚 ； 耳石 ； 日齡 ； 孵化日 ； 淡水河口

並列摘要

Ages, growth, and hatching dates of grey mullet Mugil cephalus L. juveniles in the Tanshui estuary of northwestern Taiwan were examined, using growth increments in otoliths of fish collected in November 1995 to March 1996 and November 1996 to March 1997. Growth increments are deposited daily, and were used to determine the ages. Juveniles were composed of multiple cohorts, and their sizes ranged between 17 and 39 mm in total length, corresponding to ages of 29 to 67 d after hatching. The growth rate during the estuarine residency was 0.45 mm d^(-1). Hatching dates back-calculated from daily ages were from October to February, which range earlier and later than the spawning period from November to January of a previously known migratory population. This suggests that grey mullet juveniles in the estuary may come from both a resident population and a migratory population, or that there are earlier and later migratory spawning populations.

並列關鍵字

Mugil cephalus L. ； Otolith ； Daily age ； Hatching date ； Tanshui estuary