해산송사리, Oryzias dancena의 산란행동 분석

Observations on the Reproductive Behavior of the Marine Medaka, Oryzias dancena

본 연구는 해산송사리, Oryzias dancena의 산란행위를 분석하여 인공산란 기술 개발에 그 목적이 있다. 실험 사육수조에서 관찰한 결과, 실험 시작 후 모든 수컷이 각자 목표로 한 암컷을 쫓아감과 동시에, 상대적으로 큰 수컷이 작은 수컷의 생식공을 공격하여 축출하는 행동(biting, expelling)을 보였다. 이후, 수컷은 암컷과 나란히 유영하며 구애행동을 보였으며, 뒷지느러미와 등지느러미를 이용해 암컷의 어체를 감싸고 방란 및 방정한 결과, 수정난은 암컷의 생식공 부근에 부착되어 있었다. 수컷이 covering 하는 동안 암컷이 재빨리 앞으로 유영하는 행동을 많은 빈도로 관찰하였는 바, 이는 암컷이 수컷의 구애행동을 거절하는 경우라고 사료된다. 총 빈도 81%의 산란행동 요인 2가지를 분석한 결과(P<0.05), 요인 1 (biting, expelling)은 암컷을 차지하기 위한 수컷의 방어 행동으로 총 빈도의 23.1%였으며(P<0.05), 요인 2 (chasing, parallel swimming, covering, reject)는 산란을 위한 행동으로 총 빈도의 59.7%를 차지하였다(P<0.05). 본 결과는 해산송사리 종 보존의 기본적 생물학적 자료 제공과 아울러 인공산란 기법에 유용한 자료로 쓰일 것이다.

The aim of this study is to observe the reproductive behavior of the marine medaka, Oryzias dancena, and determine the factors of reproductive behavior to provide useful information for improving their artificial reproduction techniques. The reproductive behavior of the marine medaka was observed in laboratory aquaria. Once the experiment began, all of the males chased the females. The males attempted to stimulate the urogenital openings of the females. While chasing a female, a large male would bite a relatively small male's anus. Larger males expelled smaller males with biting, and the defeated males were barred from the female. After the other males were expelled, the remaining male approached and drew alongside the female. The male's dorsal and anal fins covered the female's body. Spawning began after complete covering took place. Spawning of males and females occurred simultaneously. The loadings for 2 factors were calculated. The calculation was restricted to 2 factors because these 2 factors explained about 81% of the total common variance (P<0.05) and the following factors possessed no practical significance. Two movements (biting, expelling) had high positive values for factor one. This factor related a male's defensive behavior to courtship behavior and spawning, and explained 23.1% of the total common variance (P<0.05). The second factor had high positive values for chasing, rejection, covering, and parallel swimming. This factor related a male's courtship behavior and female's defensive behavior to spawning, and explained 59.7% of the total common variance (P<0.05). This research provided basic biological data for the conservation of this species and useful information for improving their artificial reproduction techniques.