台灣周圍海域黑䱛Atrobucca nibe系群之研究

Abstract

黑䱛(Atrobucca nibe) 為石首魚科(Sciaenidae)魚類，俗名黑口，分布於西太平洋日本、台灣至印度洋西岸之沿海海域，具有底棲性魚類的生態特性，主要捕獲方式為底拖網、流刺網、延繩釣具以及定置網等。早期研究指出黑口在西太平洋之中國東海有北、中、南三個良好漁場，其中南方漁場水域包含了部分的台灣北部海域，然而台灣周圍海域皆有黑口漁獲，過去研究中，台灣北部與龜山島海域之生殖期較短，而西南海域生殖季較長；北部與龜山島海域雌魚較多，西南海域雄魚較多，因此引發本研究域欲探討該資源在三海域中是否同屬同一系群。本研究蒐集該三處海域之樣本，分析比較體長頻度、月別肥滿度、生殖期、卵巢切片、成熟體長、性比以及耳石核心區、核心至邊緣碳氧穩定同位素，並且以北部海域之鱗片進行讀輪以獲得成長方程式，綜合漁業生物學多項資料以及穩定同位素分析來判斷台灣周圍海域的系群。結果如下，三海域的體長組成以17-19公分為主，但組成之體長結構分布略有不同，經對數轉換體重與體長關係式檢定，三海域雌雄魚的斜率與截距均無差異，因此使用雌雄合併關係式，其中北部與東北部的斜率沒有顯著差異(p> 0.05)，北部與西南部以及東北部與西南部斜率達顯著差異(p< 0.05)。三海域肥滿度比較結果顯示，北部與東北部無顯著差異，北部與西南部以及東北部與西南部具有顯著差異。生殖期北部為5-6月、東北部7月，西南部1-5月，經卡方檢定北部與東北部之性比皆不等於1:1，雌魚較雄魚多，西南部符合性比等於1:1假設；三海域之卵巢切片結果皆顯示了此魚種的產卵型態為分批同步成熟型(group synchronous) 。三海區之耳石核心區碳氧穩定同位素中位數經Kruskal-wallis檢定皆未達顯著差異(p> 0.05)。北海海域成長方程式為Lt =56.29 (1- e-0.12 (t+1.56))。綜合上述漁業生物學及耳石核心區碳氧穩定同位素，結果顯示三海域主要的體長組成相似、由耳石核心區碳氧穩定同位素值推測的仔稚魚期經歷近似環境、卵巢發育型態同屬分批同步成熟型，因此推測應屬同一遺傳族群，但是該族群經歷不同環境，致北部與東北部對西南部在肥滿度、體重體長關係式、生殖期、性比皆有差異，因此北部與東北部海域應歸屬同一系群(stocks)，而西南海域為另一系群，未來將持續探討南北不同系群可能的原因。

Atrobucca nibe distributing in coastal water from the west Indian Ocean to the west Pacific Ocean is one of the species in Sciaenidae. Benthic layer with sand and mud is the habitat of Atrobucca nibe, thus the fishery of Atrobucca nibe usually use trawler as fishing method or gill net、pole and lines boote、long line and set net. There are three main fishing ground in the East China Sea, and the southern fishing ground includes north Taiwan although A. nibe can be found in all surrounding waters. Past researches indicated that the spawning seasons of A. nibe in north Taiwan was shorter than south west Taiwan and north Taiwan had more females than south west Taiwan according to the sex ratio, hence research on identifying the stock of A. nibe between areas is need. We collected A. nibe from three different habitats and analysed length composition, length-weight relationships, condition factor, spawning season, the length of mature, sex ratio, histological examination of ovary, carbon and oxygen stable isotope of otolith and using scale to determine the growth equation of north Taiwan. In the result, length composition seems different among three regions. The slope in linear regression of weight and length and condition factor in north and north east Taiwan is similar but different between north and south west Taiwan, north east and south west Taiwan. The spawning season in north Taiwan is from May to June, July in north east and January to May in south west. The amount between female and male is different in north and north east Taiwan but similar in south west. The type of reproduction is group synchronous base on histological examination of ovary in three region. There is the similar value in carbon and oxygen stable isotope of otolith in core region and the growth equation in north Taiwan is Lt =56.29 (1-e -0.12 (t+1.56)). The result of stable isotope of otolith indicate that they experienced similar environment when they were young. According to the different in condition factor, relationships of weight and length, sex ratio and spawning season between north and south west Taiwan, we should separate A. nibe in Taiwan into two different stock. We should investigate the reason making difference in north and south west Taiwan in the future.