1991 Fiscal Year Final Research Report Summary
System and Function of Maturation and Spawning in Japanese Sardine Sardinops Melanostictus, in Captivity and Wild.
| Project/Area Number |
02660197
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | Faculty of Agriculture, Kyushu University |
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Principal Investigator |
MATSUURA Shuhei Kyushu Univ. Fac. Agr., Assoc. Prof., 農学部, 助教授 (80038215)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUI Seiichi Kyushu Univ. Fac. Agr. Assist. Prof., 農学部, 助手 (60038297)
KITJIMA Chikara Kyushu Univ. Fac. Agric, Prof., 農学部, 教授 (50204889)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Sardine / Oogenesis / Spermatogenesis / Maturation / Spawning / Ovulation inducing / Postovulatory follicle / Steroid hormone |
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| Research Abstract |
The criteria of ovarian maturity and the maturity rates according to lengths and ages were studied for wild Japanese 'sardines. The maturity of ovary was classified into 6 categories histologically based on the developmental stages of the most advanced oocytes, the occurrence of postovulatory follicles and the occurrence of atresia. Gonad and blood samples were taken throughout the year from captive males and females of the Japanest sardine. and changes in serum levels of gonadal steroids were examined in relation to the annual gonadal cycle In both sexes. On the basis of gonadal histology. the annual gonadal cycle was divisible into four periods. Changes In serum levels of gonadal steroids were correlated with the annual gonadal cycle. Under captive conditions, female fish did not mature and spawn spontaneously, although oocytes developed up to the end of vitellogenic growth. The effects of several steroids on the maturation of follicle-enclosed oocytes of sardine were examined In vit
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ro, and 17alpha, 20beta-DP. was found to be the *ost potent inducer of maturation. This suggests that post-vitellogenic oocytes of. the Japanese sardine in captivity have an ability to respond to an appropriate hormonal effector and subsequently to resume selotic maturation. In the present study. maturation and ovulation were successfully Induced In Japanese sardine with vitellogenic oocytes by us ing luteinizing hormone-releasing hormone analogue (LHRH-&), and In combination with human chorionic gonadotropin. The histological features of postovulatory follicles and the developmental stage of residual oocytes after ovulation suggested that sardine spawned at least twice during a spavnlng season. Females with atretic ovaries shoved low values in condition factor compared with females with no atresia in the ovarlies. Frequency distribution of oocytes diameter showed polymodal, and the most advanced group of oocytes separated from the developing group of oocytes In diameter frequency distribution when they attained the migratory nucleus stage. Batch fecundity (BF) was shown as BF=1.68x 10^<-10>BL^<6.19> where BL= body length (ne). Less
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