Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and ...
Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and oviparous. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (June to September), and spent/inactive stage (September to February). The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. Percentage of first sexual maturity of female and male clams ranging from 40.0 to 45.0 mm in shell length was over 50%, and all clams over 50.0 mm in shell length sexually matured. Female and male clams ranging from 40.0 to 45.0 mm in shell length are considered to be two years old. Therefore, we assume that the hard clams of both sexes begin reproduction from two years of age. The mean number of the spawned eggs increased with the increase of size (shell length) classes. In case of artificial spawning induction, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-18 days (average 17 days).
Reproductive cycle with the gonadal phases, first sexual maturity, artificial spawning amount by the size and spawning interval of the hard clam, Meretrix lusoria were investigated by histological observations and morphometric data by artificial spawning induction. Meretrix lusoria is dioecious and oviparous. The reproductive cycle of this species can be classified into five successive stages: early active stage (January to March), late active stage (February to May), ripe stage (April to August), partially spawned stage (June to September), and spent/inactive stage (September to February). The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. Percentage of first sexual maturity of female and male clams ranging from 40.0 to 45.0 mm in shell length was over 50%, and all clams over 50.0 mm in shell length sexually matured. Female and male clams ranging from 40.0 to 45.0 mm in shell length are considered to be two years old. Therefore, we assume that the hard clams of both sexes begin reproduction from two years of age. The mean number of the spawned eggs increased with the increase of size (shell length) classes. In case of artificial spawning induction, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawnings). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning was estimated to be 15-18 days (average 17 days).
* AI 자동 식별 결과로 적합하지 않은 문장이 있을 수 있으니, 이용에 유의하시기 바랍니다.
제안 방법
A total of 300 clams ranging from 40.0 to 79.4 mm in shell length (over size of 50% of first sexual maturity) were reared for 3 days in two FRP rearing aquaria (1.0 m x 1.5 m x 0.5 m) for 3 days without food supply before the beginning of the experiment. A design for the first spawning experiment on June 1-2, 2003 was shown in Table 3.
The total number of the third spawned eggs per individual by shell size class were counted using the same counting method as in the first and second spawning experiments. To confirm the spawning interval of this population, the required days for the third spawning of the second spawned individuals were checked by the same experimental conditions used for the second spawning experiments in the laboratory.
대상 데이터
Spawning reaction rate by artificial induction and the number of spawned individuals were summarized in Table 3. A total of 102 female clams spawned after the first spawning induction between June 1, 2003 and June 2, 2003 in the indoor laboratory. A total of 52 clams among the first spawned 102 females (spawning reaction rate, 50.
성능/효과
Age or shell length can be used as a convenient indicator. According to the results of percentages of first sexual maturity, those of females and males of 40.0-45.0 mm in shell length were 54.8% and 56.7%, respectively, and 100% in those of females and males > 50.0 mm in shell length. According to the growth curves for the mean shell length fitted to von Bertalanffy's equation on by Kim (2005), individuals ranging from 40.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.