台灣海峽南部產正蜥魚成熟與產卵之研究

Abstract

本研究從1998年3月至1999年2月，逐月至高雄鼓山魚市場採集作業於台灣海峽南部台灣淺灘附近海域的中小型單船拖網漁船所漁獲的狗母魚，假設每一艘漁船皆為逢機樣本船，按月逢機採取一艘漁船的一箱樣本魚。利用卵巢組織切片及卵徑頻率分佈分析，來探討台灣海峽南部產正蜥魚之成熟與產卵。 根據組織切片觀察結果，可將魚卵發育分為 8 期，分別為染色質核仁期、周邊核仁期、表層泡期、卵黃第一期、卵黃第二期、卵黃第三期、卵核移動期、排卵前期。並依卵巢外部型態及內部卵細胞發育狀態，將卵巢發育分為 6 期，分別為未發育期、發育期、成熟期、產卵期、產卵後期及產完卵期等。及以精巢外部型態將精巢發育分成 3 期，分別為未發育期、成熟期及排精後期。正蜥魚卵巢的卵徑大小組成為非同步型，且是多次產卵型的魚類，整年都有生殖行為。生殖高峰在 4-5 月及 10-11 月。雌、雄魚的 50％成熟體長分別為 30.8cm 及 29.5cm。總性比為 1 : l，但隨體長的增加雌魚比率也增加。本研究定義分批孕卵數為吸水卵個數，平均每克卵巢重有 1,532 顆，或平均每尾魚 61,616 顆；生殖腺指數和分批孕卵數呈線性關係。在假設卵巢內含有吸水卵的雌魚為正在進行產卵的魚下，所估計雌魚的產卵比率為 0.34，或雌魚約每 2.9 天就產一次卵。

The specimens used in this study were sampled monthly at Kaohsiung Gusan Fish Market from the landing of the baby trawlers that operated in the Southern Taiwan Strait., i.e., Taiwan Bank from February 1998 to March 1999. This study investigated the maturity and spawning of lizard fish, Saurida undosquamis, using histological observation of ovary and oocyte analysis. Oocyte development is divided into eight stages from histological observation, i.e., chromatin nucleolus stage, perinucleolus stage, cortical alveolus stage, primary yolk stage, secondary yolk stage, tertiary yolk stage, germinal vesicle migration stage, and preovulation stage. Ovary development is divided into six stages from the appearance and oocyte development styles in the ovaries, i.e., immature, developing, mature, spawning, spawned, and spent. Testis development is divided into three stages from the appearance of testis, i.e., immature, mature, and spawned. The oocyte distribution is asynchronus, so the lizard fish is a multiple spawner and can spawn all over a year. Two spawning peaks appear in April - May and November. The 50％ mature fork length (ML50) is 30.8cm and 29.5cm for female and male, respectively. The sex ratio of total sample fish is 1:1, however, the female will increases when fork length increases. This study estimates batch fecundity by counting hydrated oocytes in the ovary. The batch fecundity is about 1,532 oocytes per grams of ovary weight or about 61,616 oocytes per fish. Under an assumption of the female with hydrated oocytes are spawning now, the spawning fraction is estimated as 0.34, or the females can spawn a time every 2.9 days.