On the Maturity and Spawning of the Greenling, Hexagrammos grammus(Temminck et Schlegel)

노래미, Hexagrammos agrammus(Temminck et Schlegel)의 성성숙과 산란

Sexual maturation and spawning of the spottybelly greenling, Hexagrammos agrammus were histologically studied under photomicroscopy by considering changes in gonadosomatic index, hepatosomatic index and fatness, egg diameter composition, first sexual maturity and fecundity. The fish samples were collected monthly at the coastal area of Tongbaeksom, Pusan, Korea from July 1991 to July 1992. The gonadosomatic index(GSI) increased in September and reached the maximum value(female 4.31, male 1.61) in November when the gonad was mature and ripe. The values were decreased suddenly during the spawning season from December, and declined from January to August. The annual variations of hepatosomatic index(HSI) appeared to be correlated with those of GSI in female but were not significantly correlated in male. HSI in female began to increase in autumn with the increase of GSI, and reached the maximum in winter when the ovary was mature. Percentages of first sexual maturity in female and male fish were 50 % in 11.0~11.9 cm and 100 % in 13.0~13.9 cm groups. Both sexes participated in reproduction from one year old. H. agrammus was considered as a polycyclic species and spawns 3 times or more in the spawning season. Number of total and mature eggs in the absolute fecundity were proportional to standard length and body weight, respectively. Number of total and mature eggs in relative fecundity were also proportional to standard length, but rather decrease with increasing of body weight. Fatness coefficients reached the maximum value(female 15.32, male 15.14) in September(growing stage), and the values were sharply decreased after spawning. Thereafter, fatness values were gradually increased, therefore, the monthly changes in fatness coefficient closely correlated with the reproductive cycle. Sex ratios of female and male sexes of this species are showed 54.18 %, 45.82 %, respectively.

1991년 7월부터 1992년 7월까지 부산시 해운대 동백섬 조간대에서 채집된 노래미, Hexagram mosagrammus를 대상으로 성성숙에 관련된 제반 형질을 조사한 결과는 다음과 같다. 1. 생식소숙도지수(GSI)는 추계인 9월부터 증가하여 11월에 년중 최고값인 암 4.31, 수 1.61을 각각 나타내었으며 12월부터 감소하여 춘하계 동안 낮은값을 유지하였다. 2. 간숙도지수(HSI)는 수컷의 경우 뚜렷하지는 않으나, 암컷은 생식소숙도지수와 동일하게 변화하여 생식소가 활성화되는 9월부터 중가하기 시작하여 11월에 2.32의 년중 최고값을 나타내었다. 3. 군성숙도는 암수 모두에서 표준체장 11.0~11.9 cm에서 50 % 이상, 13.0~13.9 cm에서 100 %로 전 개체가 생식에 가담하는 것으로 나타났다. 4. 성숙 및 산란기인 9월에서 12윌사이 난소내 난경조성의 결과에서 노래미는 한 산란기에 3회 이상의 산란을 행하는 다회 산란종으로 밝혀졌다. 5. 총포란수와 성숙란수는 체장에 비례하여 증가하였으나, 전중과의 관계에서는 감소하는 경향을 나타내었다. 6. 비만도는 성장기인 9월에 암수 각각 15.32, 15.14로 최고값을 보인 후 산란기를 지나며 크게 감소하였으며, 3월부터는 다시 서서히 증가하였다. 따라서 비만도의 변화는 생식주기와 밀접한 관계를 가지고 변화하는 것으로 나타났다.