Reporter : huang hsiao-ting Fishery biology of purpleback squid, Sthenoteuthis oualaniensis, in the northwest Indian Ocean Chen Xinjun﹡，Liu Bilin ，Tian Siquan，Qian Weiguo ，Zhao Xiaohu Fisheries Research (2007)83 : 98-104 Reporter : huang hsiao-ting 1

natural mortality, high growth rate and significant production Cephalopoda (頭足綱) Order Teuthida (管鱿目) Family Ommastrephidae (真鱿科) Genus Sthenoteuthis (南鱿屬) Scientific Sthenoteuthis oualaniensis (南魷、鳶烏賊) Common Name Purpleback flying squid 前人研究指出最大體長為69公分，，而生活史最長為0.5-1歲，頭足類擁有多樣的生態情況，包括了種內結構複雜，高繁殖力，生活史短，，成長快速，高自然死亡率及有顯著的產量。這些特徵使得頭足類在理論及應用研究上是令人感到興趣的。 complex intraspecific structure, high fecundity, short life cycle, high natural mortality, high growth rate and significant production

南魷廣泛分佈在印度洋與太平洋的熱帶與亞熱帶海域，東到美洲沿岸，西到紅海，又以西北印度洋資源最為豐富，本篇研究海域主要為西北印度洋，

Previous studies… The squid density in the area from 20◦N to 22◦N reached 6.5t km−2 and the area between 14◦N and 15◦N even reached up to 12–42t km−2 (Nesis, 1993). Three populations with distinguishable size ranges were identified (Yatsu, 1997; Yatsu et al., 1998). 從1970年開始就有學者注意南魷的資源，關於南魷先前的研究，在1993年由南西斯這位學者提出，南魷在北緯20-22度的密度約有一平方公里有6.5噸，而在14-15這之間的海域，則高達了12-42公噸之多。1997.1998年時，學者發表了南魷有三種族群，，可經由體長大小來辨別鑑定，而在 These studies suggest that the squid could sustain higher exploitation levels in the future.

objective This study describes the biological features derived from the data collected during three scientific surveys for S.oualaniensis undertaken by the Chinese squid jigger vessels in the high sea of northwestern Indian Ocean. 因此，收集更多關於南魷分布與漁業生物方面的資訊，所以本篇研究主要描寫南魷生物特性的取得集資料分析，利用魷釣船在西北印度洋公海附近，進行科學性的觀察及研究。

Materials and methods Total:2992 材料方法 採樣船為4艘，表一為4艘樣本船的設備，包括船長、噸位、馬力、集魚燈瓦數等。表二為調查時間、海域、站數、捕獲樣本數及捕獲體長範圍。時間有2003年9-11月，2004年9月-2005年3月，2005年3-4月，總捕獲樣本數有2992尾，捕獲的海域如下 Total:2992

sea surface temperature (SST) Record : fishing position sea surface temperature (SST) number of jig lines in use (eight jiggers per line) fishing depth time at the beginning and end each drift, and total catch 依照3個時間，所捕獲樣本的海域範圍為如上，再捕獲的同時，紀錄魚場位置、海表面水溫、釣線使用的鉤數、漁獲深度、時間及總漁獲數。

Data on sex and maturity stage on a scale of Lipinski (1979) : Both sexes were measured in dorsal mantle length (to 1mm) and weighted to 10g. Data on sex and maturity stage on a scale of Lipinski (1979) : ( i.e. I-II, immature；III, maturing； IV-V, mature；VI, spent). The degree of stomach fullness was recorded on scales as follows : (0, stomach empty; 1, little content; 2, stomach less than half full; 3, stomach more than half full; and 4, full stomach). 樣本帶回實驗時，測量體常體重，那之後判別性別及成熟階段，成熟階段則是根據這位學者的判別法，總有6種階段，繼續則判別為內容物， 分成5個狀態，之後分析其體長體重關係，而本研究另探討日輪， BW = a MLb : The relationship between the mantle length (mm) and total body weight (g) .

(硬化之樹脂) (慢速切割機) (包埋板)

Results 3-1 catch data + The catch totaled 1570t 42.5% 6.6% 結果在每日漁獲方面，在圖二x軸代表每日魚獲量，y軸代表頻度，在本研究總漁獲量為1570噸，每日漁獲小於一約佔了6.6%，而超過5以上則占了42.5%，在這三個觀察時間，可以看到圖三明顯的看出，主要的漁場為於這個位置，位於當地湧昇流邊緣，也發現了沒有其他魷魚在此海域被捕獲 The catch totaled 1570t

3-2 population structure Sex ratio (M:F) - 1:30.5 Male : 26 - 30 cm Female : 30 - 36 cm 48 - 54 cm 而在族群結構部分，先看圖四，x軸表體長，y軸表頻度，雌性為白色 總數2897尾，雄性為紅色.總數為95尾，性比呈現1:30.5…而雄性主要體長分佈在26-30公分，，雌性則有兩群，主要分佈30-36公分和48-54公分，在表三作者則利用2*2方格來表示族群結構，南魷因緯度空間的不同而有不同的體長大小，而分成三個族群，北緯18以北有大於400mm的南魷分佈，而在北緯12-18之間則有300-400mm南魷分佈，在北緯12以南則是由小於300mm的南魷為主要體長，而在經度空間方面，就沒有類似結構的現象發生。 < 300 mm 300-400 mm > 400 mm

3-3 ML-weight relationships

3-4 Maturity 圖六則為本研究所採集的樣本各個成熟階段的頻度，x軸代表成熟階段，，y軸代表頻度，藍色為\雌性，白色為雄性，先看到雄性部分，在階段2以上約占了88%以上，是佔了較多的部分，而在磁性方面，明顯看出主要為階段1及2，是佔了較多，成熟345階段則是頻度較小，在表四方面為不同緯度及磁性南魷成熟階段的變化，隨著緯度的增加階段1的是減少的，而階段45則是隨著緯度增加而增加，明顯看出已成熟的個體是片佈在每個海域，

3-5 Age 88-363 day ★ ★ ★ 在日齡方面，作者只採用2004-2005的樣本去回推算孵化日，這些樣本的孵化日則分布在2004年，可以看到圖七a，所推算的樣本孵化日範圍為88-363天，主要分布150-270天，在b圖方面，主要孵化月份是在3-5月之間，占了整體的57.8%，

3-6 Diet Most of the stomachs analyzed had food remains and only 8% were empty. The stomachs contained three major groups : fish, cephalopods and crustaceans . All the species remains in the stomach were identified as Cypselurus spp(飛魚) and S. oualaniensis(南魷), and more than 60% of the stomachs showed the evidence of cannibalism. 在南魷攝食方面，在全部樣本中，只有8%是空胃，就是沒有胃內容物，那作者分析胃內容物主要為魚類、頭足類及甲殼剛，再深入的鑑定主要為飛魚及南魷，有超過60%的樣本胃內容中，有嚴重的殘蝕現象，

Discussion The majority of catch was located in the areas defined by 15°N– 18°N and 60°E–62°E and by 18°30N–20◦N and 62°30E–64°E. The squid distribution is also closely to sea surface temperature and the optimal SST for the squid appears to range from 25°C to 28°C (Chen and Ye, 2005).

three populations with different ML existed in the Arabian sea (Yatsu,1997).Our results are consistent with the previous results. Based on the squid ML composition and maturity from the samples in this study, we conclude that several groups of different sizes may exist in addition to the above three forms. RAPD (分子標誌) too small – commercial jiggers (Nesis 1993).

Sex ratio- 1:30.5 (F:M) seasonal variation, (F:M) was 1:0.24 in summer, 1:0.52 in winter. In the area south to 16°N, most of the squid were in the maturity stages I and II. In the area north to 16°N the squid were generally in the maturity stages IV to V. This study also suggests that S.oualaniensis may spawn all year. the peak spawning took place in March to May, which confirmed the conclusion by Chesalin(1994).

S.oualaniensis is thought to have life span of less than 1 year. All the species remains in the stomach were identified as Cypselurus spp(飛魚) and S. oualaniensis(南魷), and more than 60% of the stomachs showed the evidence of cannibalism(殘食).

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Phylum Mollusca 軟體動物門 Cephalopoda 頭足綱 Nautiloidea 四鰓亞綱 (鸚鵡螺亞綱 ) Coleoidea 二鰓亞綱 Decapodiformes 十腕超目 Octopodiformes 八腕超目 Sepioidea 烏賊目 Sepiolida 耳烏賊目 Spirulida 旋殼烏賊目 Teuthida 管魷目 Octopodida 章魚目 Vampyromorpha 傘蛸目 Nautiloidea 鸚鵡螺目 Oegopsida 開眼亞目 Myopsida 閉眼亞目