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Spatial and temporal variations in life-history traits and statolith trace elements of Uroteuthis edulis in the southern East China Sea
|Authors: ||Liao, Ying-Ju|
|Contributors: ||NTOU:Institute of Marine Affairs and Resource Managemen|
Uroteuthis edulis;statolith;life-history traits;trace element;population structure;southern East China Sea
|Issue Date: ||2020-01-20T06:08:01Z
|Abstract: ||劍尖鎖管Uroteuthis edulis分布於西太平洋與印度洋之陸棚及沿岸水域，在其分布範圍皆有商業開發。目前對東海南部陸棚水域劍尖鎖管族群之成長與成熟已有初步瞭解，但此族群與臺灣北部不同水域(臺灣海峽與宜蘭灣)族群之關連性(分布與洄游)，尚不清楚。本研究應用生活史參數及平衡石微量元素含量分析，探討東海南部三水域(東海南部、宜蘭灣和臺灣海峽)劍尖鎖管之族群結構，主要目的有：(1)探察三水域劍尖鎖管(不同孵化群)成長與成熟參數之變異；(2)探察三水域劍尖鎖管平衡石微量元素含量之變異。並由此探討東海南部三水域劍尖鎖管族群之關連性。本研究在2016年5月至2017年4月間，每月至基隆八斗子漁港(東海南部陸棚SECS)，宜蘭大溪漁港(宜蘭灣YLB)，及澎湖鎖港漁港(臺灣海峽TS)採集劍尖鎖管，共計3344尾。劍尖鎖管體長以SECS群較大(F: 258 mm，M: 294 mm)，TS群較小(F: 169 mm，M: 163 mm)。劍尖鎖管之體長–體重關係式在三水域間有顯著差異(p <0.001)。各水域每月至少判讀20尾鎖管之平衡石，共成功判讀753尾。由捕獲日期與平衡石輪數回算孵化日期，SECS群之孵化高峰為12-2月，YLB群為1-3月，TS群為1-4月。依個體孵化後三個月經歷之海水溫度，可將其分為二季節群：冷水群(cold cohort, CC)，為1-5月；暖水群(warm cohort, WC)，為7-11月。體長–日齡資料套適結果顯示，CC群在三水域可以直線式、乘冪式或指數式描述；WC群則以直線式或乘冪式描述。成熟體長在同一季節群以SECS群及YLB群較大，TS群較小。在同一水域則以CC群較大。成熟日齡亦具相同趨勢。各水域每季取3尾鎖管平衡石，應用液態進樣系統耦合電漿質譜儀(ICP-MS)檢測9種微量元素。結果顯示，Ba/Ca比在三水域有顯著差異(P = 0.05)。應用多變量統計方法探察劍尖鎖管生活史參數與平衡石微量元素濃度之時空間變化，結果顯示鎖管生活史參數在空間群(SECS與YLB群)之差異，大於季節群(CC與WC群)之差異；而平衡石微量元素含量在季節群(CC與WC群)之差異，大於空間群(SECS與YLB群)之差異。整體而言，劍尖鎖管SECS群與YLB群可能有維持交流，而與TS群較無關連。此結果建議，三水域之劍尖鎖管族群可能受海洋環境(洋流)之影響，具季節性變化。而生活史參數與平衡石微量元素含量之差異，可能反映不同水文參數之結果。此結果有助於瞭解東海南部水域劍尖鎖管之族群結構及關連性，並可提供規劃漁業管理措施之參考。|
The swordtip squid Uroteuthis edulis distributes in the temperate and tropical neritic waters in the Indo-Pacific regions. The species is a target by fisheries across its distributional range. Previous studies have shown information on growth and maturation of the squid in the southern East China Sea (SECS), while few study on population connectivity of the squid in the vicinity waters off North Taiwan. In this study life-history traits and statolith elemental concentrations of U. edulis were analyzed to explore population structure in three regions (southern ESC shelf, Yilan Bay and Taiwan Strait) of the southern ECS. The objectives are: (1) to explore spatial and temporal variation in growth and maturation parameters of the squid from three regions; (2) to investigate spatial and temporal variation in statolith elemental composition of the squid from three regions. Squid samples are collected monthly from Badouzi (SECS), Dasi (Yilan Bay, YLB) and Sougang (Taiwan Strait, TS) from May 2016 to April 2017. A total of 3344 squid was collected. The squids in SECS (F: 258 mm, M: 294 mm) were larger than those in TS (F: 169 mm，M: 163 mm). The ML-BW relationship of the squid was different significantly among three regions. A subsample of 753 squids were processed for age determination by statolith microstructure analysis. The back-calculated hatching months peaked in December to February for squid in SECS, in January to March for YLB and in January to April for TS. Two seasonal cohorts could be decided from the environmental conditions during early life history (three months), cold cohort (CC) hatching from January to May and warm cohort (WC) hatching from July to November. The ML-age data of the CC squids could be described by linear, power or exponential functions, while the WC squids could be described by linear or power function for both sexes in three regions. ML at maturity of squids in SECS and YLB were larger than that in TS for the same cohort. A similar pattern was found for age at maturity of squids in three regions. A subsample of 15 squids were selected for statolith elements analysis (9 elements) using solution-based inductively coupled plasma mass spectrometry (ICP-MS). The Ba/Ca ratio shown significant difference in squids among three regions. The results of multivariate analysis suggested that the variations in squids between regions (SECS and YLB) were larger than those between cohorts (CC and WC) based on life-history traits analysis, while the variation in squids between cohorts (CC and WC) were larger than those between regions (SECS and YLB) based on statolith elemental analysis. In summary, there was potential connectivity for squids between SECS and YLB, while few connectivity with TS. The squid populations in three regions might be influenced by oceanographic environments (currents), and with obvious variability seasonally. The distinct patterns between life-history traits analysis and statolith elements analysis could respond to the effects influences by different hydrological parameters. This result could be helpful in understand population structure and connectivity of the squid in the southern East China Sea, and could provide critical information for planning of fisheries management measures.
|Appears in Collections:||[海洋事務與資源管理研究所] 博碩士論文|
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