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本研究根據2003-2019年於新港魚市場測量99,1527尾鬼頭刀體長資料(雌魚55,649尾,雄魚為34,884尾)進行體長頻度及性比(雌性比例)進行了分析。研究顯示當體長增加時雄性比例高於雌性。根據2017-2019年新港魚市場漁獲拍賣資料之漁獲比例分析顯示,可區分8個主要漁獲來篩選漁業別,區分出鬼頭刀延繩釣漁業漁獲組成進行混獲分析。由漁獲組成分析顯示,鬼頭刀延繩釣漁獲鬼頭刀佔83.77%,混獲率僅16.23%,月別混獲率介於10.6-31.6%之間。當鬼頭刀盛漁期期間3-5月及10-12月期間混獲率分別為15.9-17.8%和10.6-16.2%,表示鬼頭刀盛漁期時混獲率較其他月別低。本研究於2018年10-11月期間於東海北部定置漁場利用彈脫式衛星標識器(PSAT)標識4尾鬼頭刀(尾叉長94–102 公分)。共記錄5-31的行為資料(Σ= 69天),從標放位置到彈脫位置的直線距離為63-204 公里。並且利用狀態空間卡爾曼濾波器結合海面溫度(SST)估算最可能的移動路徑,結果顯示,標識之鬼頭刀主要向北移動。垂直移動深度從海表面至94 公尺深,棲息環境溫度範圍為17.78-23.05°C。在白天和夜間鬼頭刀分別有80%和40%以上的時間棲息於海表面水層,且晝夜間棲息深度有明顯差異,表示鬼頭刀夜間期間比白天更廣泛的垂直移動,然垂直移動主要限於混合層內,並且沒有發現越過溫躍層的現象。根據移動棲息溫度與SST的差值顯示,鬼頭刀深度分佈似乎受到5°C變化的限制。鬼頭刀晝夜垂直移動的變化主要在曙暮光期間轉移。這種垂直移動模式的晝夜差異可能反映了獵物的可用性和分佈的變化。本研究之結果將有助於該物種之生態保護漁業管理之重要資訊。

In this study, length-frequency and sex ratio (proportion of females) of dolphinfish were analyzed based on 88,902 (54,717 were females and 34,185 were males) samples measured in Shingkang fish market during 2003 to 2018. The proportion of male becomes higher than females when body length increased. Catch the proportion of auction data in the Shingkang fish market from 2017 to 2019. The analyze catches ratio was to 8 main catches, and the dolphinfish longline fishery catch composition was selected for by-catch analysis. The 83.77% of the catch dolphinfish for dolphinfish longline, the by-catch are only 16.23%, and the monthly by-catch shows that the between 10.6-31.6%, which during the fishing season of dolphinfish the by-catch from March to May and October to December were 15.9-17.8% and 10.6-16.2% respectively, indicating that the by-catch during the fishing season of dolphinfish was lower than other months. Pop-up satellite archival tags (PSATs) were deployed on four dolphinfish (94–102 cm fork length), caught using set-nets in the northern East China Sea during October and November of 2018. Dolphinfish were tracked for periods of 5–31 days (Σ = 69 days) and linear displacements ranged from 63 to 204 km from deployment to pop-up locations. Most probable tracks calculated by the state-space Kalman filter, augmented with sea surface temperature (SST), suggested the tagged fish made primarily northward movements. Diving depths ranged from the surface to 94 m and ambient water temperatures occupied ranged from 17.78 to 23.05 °C. Dolphinfish spent >80% and >40% of their time near the surface in the daytime and nighttime, respectively and the distribution of time spent at depth and temperature was significantly different between daytime and nighttime diving activity. Dolphinfish undertook more extensive vertical excursions during nighttime than daytime but vertical movements were largely confined to the mixed layer and did not cross the thermocline. Depth distributions appeared to be limited by a 5 °C change relative to SST. Changes in diel vertical movement patterns mainly occur during crepuscular transitions around twilight and it is possible diel differences in vertical movement patterns reflect changes in prey availability and distribution. This report will be useful to inform fisheries management for possible habitat protection for this species.