曾萬年臺灣大學：漁業科學研究所李浩祥Lee, Hao-HsiangHao-HsiangLee2007-11-282018-07-062007-11-282018-07-062007http://ntur.lib.ntu.edu.tw//handle/246246/59305日本海鰶 (Nematalosa japonica) 為大肚溪河口域魚類的優勢種，至今其洄游模式、年齡及成長等生活史資訊皆不清楚。本研究藉由耳石的特殊結構及微化學組成，來了解日本海鰶在大肚溪的初期生活史、年齡與成長，及其在海水與淡水之間的移動情形，以便釐清日本海鰶是否為溯河性魚類，以及其在台灣河川環境多變情況下的生活史多樣性。 由體長頻度分佈及生殖腺指數的月別變化得知大肚溪日本海鰶的產卵期為每年2 ~ 4月之間。耳石日周輪結構及鍶鈣比的時序列變化，顯示兩個特殊耳石標記：(1) 仔魚變態為稚魚時所形成的變態輪 (Metamorphosis check)，變態日齡為 27.7 ± 5.3天 (n = 40)；及 (2) 稚魚回到河口中上游時所形成的河口輪 (Estuary check)，其日齡為47.2 ± 9.2天 (n = 18)。根據耳石的年輪結構，所建立的日本海鰶成長方程式為：Lt = 218.3 (1- e - 0.31 ( t + 0.8 ) )。其極限體長 (L∞) 為218.3 mm，成長率 (K) 為0.31 yr-1。 日本海鰶耳石鍶鈣比與水體中的鹽度，呈顯著正相關關係 (p < 0.05)。鹹淡水的界線之鍶鈣比值為3.1 ‰。耳石鍶鈣比的時序列變化顯示，日本海鰶的初期生活史呈現多重的漂散模式，而幼魚皆於河口區哺育，成魚可能至上游淡水環境產卵。此外，隨著年齡的增加可明顯區分為兩種洄游模式：(1) 高鹽度型：耳石平均鍶鈣比值較鹹淡水界線高，其棲地利用偏向河口下段的海水區，此型佔所有分析樣本的36 % (n = 36)；及 (2) 低鹽度型：耳石平均鍶鈣比值較鹹淡水界線低，其棲地利用偏河口上段的淡水區，此型佔44 %。兩型的成長方程式有顯著性差異 (p < 0.05)，高鹽度型者成長較慢，但極限體長較大；而低鹽度型則成長較快，極限體長較小。日本海鰶棲地利用與成長策略的分歧現象，可能與環境條件變異性的適應策略有關。其應變策略是否為遺傳變異，或是一種逢機現象，則有待研究。Japanese gizzard shad (Nematalosa japonica) is a dominant clupeid fish in the Tatu creek estuaries. Its life history information such as migratory pattern, age and growth is not clear so far. In this study, otolith structure and microchemistry of Japanese gizzard shad were used to study their age, growth and migratory history. Monthly variations of fish length frequency distribution and gonadosomatic index indicated that spawning season of this fish was from February to April. The chronological changes of otolith daily growth increment and Sr:Ca ratios patterns presented two otolith checks: (1) metamorphosis check which was assumed to be formed when the fish metamorphosed from larvae to juvenile stages. The aged at metamorphosis was estimated to be 27.7 ± 5.3 days (n = 40) after birth; and (2) estuarine check, which was formed when the juveniles returned to the upper reach of the estuary. The age of return was 47.2 ± 9.2 (n = 18) days after birth. The age-length data back calculated from otolith annulus were fitted with von Bertalanffy growth equation as Lt = 218.3 (1- e - 0.31 ( t + 0.8 ) ), where asymptotic length (L∞) was 218.3 mm and growth rate (K) was 0.31 yr-1. The Sr:Ca ratios in otolith of Japanese gizzard shad was positively correlated to the salinity of ambient water. (p < 0.05) The regression of otolith Sr:Ca ratios on salinity was y = 0.05 x + 3.10, with an intercept, the saline-freshwater boundary at 3.1 ‰. The chronological patterns of otolith Sr:Ca ratios showed that multiple types of drift existed in early life history, and the fish used estuary as nursery ground. The migratory patterns of the fish in the estuary can be classified into two types: (1) high salinity type (H type), the mean Sr:Ca ratios were higher than the saline-freshwater boundary, indicating the fish lived in the lower reach of the estuary, which consisted of 36 % of the fish examined (n = 36); and (2) low salinity type (L type), the mean otolith Sr:Ca ratios were less than the saline-freshwater boundary, indicating that the fish lived in the freshwater environment of the upper reach of the estuary, which consisted of 44 % of the fish examined. The otolith Sr:Ca ratios also indicated that the adults might migrated annually to the freshwater to spawn. The growth performance was significantly different (p < 0.05) between two types, with lower growth rate and higher asymptotic length for H type; but higher growth rate and lower asymptotic length for L type. If the differentiating habitat utilization and growth strategy of Japanese gizzard shad between these two types is due to random adaptations to the variability of environmental conditions or genetic determined needed further study.口試委員會審定書………………………………………………………………………i 謝辭……………………………………………………………………..…………….…ii 中文摘要………………………………………………………………………………..iii 英文摘要………………………………………………………………………………..iv 目錄……………………………………………………………………………………..vi 壹、前言 1.1.魚類的洄游模式………………………………………………………………1 1.2.日本海鰶的研究現況……………………………………………………........2 1.3.耳石的研究與應用……………………….…………...…………………........3 1.3.1.耳石的形成與特殊結構……………………………………………….3 1.3.2.耳石的微化學組成…………………………………………………….6 1.4.研究動機及目的………………………………………………………………7 貳、材料與方法 2.1.研究地點的地理特徵………………………………………………………....8 2.2.樣本的採集與處理…………………………………………………………....8 2.3.耳石樣本的製備……………………………………………………………....9 2.4.耳石日周輪及年輪的判讀與測量……………………………………………9 2.5.耳石中鍶與鈣濃度比的測量………………………………………………..10 2.6.資料處理……………………………………………………………………..11參、結果 3.1.大肚溪河口域之溫鹽變化…………………………………………………..12 3.2.單位漁獲量之時空分佈……………………………………………………..12 3.3.平均體長及體長組成之時空變異…………………………………………..12 3.4.生殖腺指數的時空比較……………………………………………………..13 3.5.耳石結構……………………………………………………………………..13 3.5.1.矢狀石的外觀………………………………………………………...13 3.5.2.日周輪及記號………………………………………………………...14 3.5.3.年輪結構及年齡判定………………………………………………...14 3.5.4.耳石大小與體長之關係……………………………………………...14 3.5.5.成長方程式…………………………………………………………...15 3.6.耳石微化學…………………………………………………………………..15 3.6.1.耳石鍶鈣比與鹽度之關係…………………………………………...15 3.6.2.鍶元素的分佈……………………………………..………………….15 3.6.3.洄游環境史的類型…………………………………………………...16 3.6.3.1.初期生活史……………………………………………………16 3.6.3.2.成魚洄游環境史之類型………………………………………17 3.6.4.兩型個體的成長方程式之比較…………………...…………………18 3.6.5.特殊洄游環境史…………………………………………...…………19 肆、討論 4.1.耳石的變態輪與變態日齡的論證…………………………………..............20 4.2.年輪的可靠性與成長參數之比較………………………………..................20 4.3.以耳石鍶鈣比作為洄游環境的指標……………………………………......21 4.4.由GSI、CPUE及耳石核心鍶鈣比來推測產卵地點的環境……………...22 4.5.棲地利用及成長策略的分化現象………………………..............................23 4.6.溯河產卵洄游習性的痕跡………………………………..............................24 4.7.成魚的向海移動現象……………………………………..............................25 伍、總結………………………………………………………....................................26 陸、參考文獻 6.1中文部分………………………………….…………………………….........27 6.2.英文部分……………………………………………………………………..28 圖……………………………………………………………………………................40表……………………………………………………………………………................597158006 bytesapplication/pdfen-US日本海鰶耳石日周輪年輪鍶鈣比年齡與成長棲地利用Japanese gizzard shadotolithdaily growth incrementsannulusSr:Ca ratiosage and growthhabitat utilizationotherhttp://ntur.lib.ntu.edu.tw/bitstream/246246/59305/1/ntu-96-R94b45008-1.pdf