利用平衡石分析東海南部劍尖槍鎖管之季節成長差異

Abstract

劍尖槍鎖管 (Uroteuthis edulis) 是臺灣北部火誘網漁業主要目標物種之一，同時也是東海南部重要的經濟頭足類之一。過去對該物種的生殖及日齡成長已有研究，但對於終年均會產卵的劍尖槍鎖管來說，探究其季節群的個體成長差異有其必要性。本研究利用平衡石分析2008年12月至2009年11月間各季節孵化的劍尖槍鎖管成長之差異。結果顯示除了夏季孵化群外，各季所孵化的雌及雄鎖管成長是以指數型為最佳 (r2 > 0.31)，日齡則均在250天以內。春生群與冬生群的鎖管可成長至較大體型 (ML > 300 mm)，而夏生群的鎖管普遍較小 (ML < 150 mm)，且冬生群的成長較春、夏及秋生群為快。推測當冬生群成長至180天時正處於春、夏時期，此時的棲息水溫正逐漸變暖，而使冬生群其後之成長快於其他三季孵化群。Uroteuthis edulis is one of the main target species of the torch-light fishery in northern Taiwan. It is also an important commercial cephalopod in the southern East China Sea. In the past, studies on reproduction and growth were conducted. The study was to exam the seasonal variability on growth of squid that spawns throughout the year. The result showed that the exponential function (r2 > 0.31) was the best fit for the growth of female and male, excepting summer hatched group. The maximum age observed was 241 days. The spring hatched group and the winter hatched group had large size ( ML > 300 mm) and the size of the summer hatched group was generally small (ML < 150 mm). The ML of winter hatched group grew faster than the spring, summer and autumn hatched groups. It is possible that the winter hatched group experienced the warmer water temperature of spring and summer at about 180-days-old, which caused the group to grow faster than the other three hatched groups after 180 days life time.