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1.
ABSTRACT: This study clarifies the annual reproductive cycle and the lunar-synchronized spawning of the spiny rabbitfish ( Siganus spinus ) that inhabit the Okinawan waters. Annual and weekly changes in the gonadosomatic index (GSI) and the histological features of the ovaries were checked. Gonadosomatic index was high during the months of May to July, and yolk-laden oocytes were observed in the ovaries from March to July. Some of the ovaries collected during June and July contained oocytes at maturation stage or ovulatory follicles. These results suggest that the spiny rabbitfish undergo active vitellogenesis and spawning from May to July. During the reproductive season (May to July), collection of fish according to the lunar phase revealed that a high GSI occurred around the time of the new moon. Cyclic oocyte development with peaks around the time of the same moon phase was also observed, suggesting that, in Okinawan waters, this species is a lunar-synchronized spawner and spawns three times.  相似文献   

2.
ABSTRACT:   This study examined the annual and the lunar cycles of ovarian activity in the forktail rabbitfish Siganus argenteus (Quoy & Gaimard, 1825) and the spiny rabbitfish Siganus spinus (Linnaeus, 1758), which were collected from the Chuuk lagoon, Federated States of Micronesia. Gonadosomatic index (GSI) increased in May and June for S. argenteus . For S. spinus , GSI increased in March, and from July to September. During these periods, the ovaries of these species contained oocytes at the tertiary yolk stage or the maturation stage, suggesting that these months are the reproductive season of the two species. During the reproductive season, weekly collection of the fish according to the lunar phase revealed that high GSI occurred around the last quarter moon for S. argenteus and the new moon for S. spinus . In the ovaries, oocytes developed synchronously, and postovulatory follicles, an indicator of spawning, were observed after the respective moon phase, suggesting that these species are restricted lunar-synchronized spawners. Comparisons of the reproductive activity of the two rabbitfishes in the Chuuk lagoon with that in Okinawa waters revealed that there is a geographic difference in the reproductive activity between habitats. However, the lunar phase for exertion of synchronous gonadal maturation and spawning is common in both regions.  相似文献   

3.
ABSTRACT:   Lunar-related spawning periodicity of the brackish damsel Pomacentrus taeniometopon was investigated by changes in gonadosomatic index (GSI) and ovarian histology. During the spawning season, GSI increased toward the week of the first and last quarter moon. Concomitant with increases in GSI, oocytes laden with yolk developed from the new/full moon to the first/last quarter moon. Postovulatory follicles appeared in the ovary around and after the first/last quarter moon. These results suggest that P. taeniometopon is a semilunar spawner and repeats spawnings twice a month with lunar periodicity during the spawning season. When the fish were reared under laboratory conditions without periodicity of tide, the spawning of P. taeniometopon occurred sporadically. It is likely that the fish uses tidal stimuli in the natural habitat to entrain reproductive activities.  相似文献   

4.
ABSTRACT:   The stage of ovarian development and annual reproductive cycle of female armorhead Pseudopentaceros wheeleri collected from seamounts of the southern Emperor–northern Hawaiian Ridge in 1993 and 1995–1996 was investigated through use of the gonadal somatic index ( GSI ) and ovarian histology. The stages of oocyte development were classified into eight developmental stages (perinucleolus, cortical alveolus, oil droplet, early yolk globule, late yolk globule, migratory nucleolus, prematuration, and maturation) based on histological characteristics. Oocytes of different size and developmental stage were present within ovaries during the spawning season. Oocyte development appears to be asynchronous and armorhead apparently spawn several times during the spawning season. The stage of the most developed oocyte was used to classify the stage of ovarian maturation. The GSI increased gradually with ovarian development. Oocytes in the perinucleolus, cortical alveolus, and oil droplet stages were present in ovaries throughout the year. Early and late yolk globule stages appeared during August–September indicating that yolk formation begins during late summer. The migratory nucleolus through maturation stages were detected during November–January. Post ovulatory follicles were present during November–March, and GSI values rapidly decreased in February. Results indicate that spawning occurs during November–February and peaks during December–January.  相似文献   

5.
《Fisheries Research》2007,83(1-3):95-100
The white croaker, Pennahia argentata (Houttuyn), is abundant in demersal fish assemblages in Ariake Sound and is a commercially important species. The reproductive biology of white croaker was studied by measurement of gonadosomatic indices (GSI) and histological examination of ovaries. Ovaries were classified into one of five maturity stages based on histological data: (1) immature/resting stage; (2) developing stage; (3) maturing stage; (4) ripe/spawning stage; (5) spent stage. The spawning season lasts from April to September but most activity is observed from May to August. Age at sexual maturity was assumed to be 1 year. Postovulatory follicles coexisted with yolk stage oocytes in histological sections of ovaries indicating that white croaker is a multiple spawner, spawning more than once in a single spawning season. Judging from the diel changes in the proportion of females with ovaries containing postovulatory follicles and oocytes at maturation stage, most females spawned in the evening between 19:00 and 21:30 h.  相似文献   

6.
ABSTRACT:   To determine the spawning season and reproductive cycle of the yellow sea bream, Dentex tumifrons , in Wakasa Bay, in the Sea of Japan off central Honshu, seasonal change in the gonadosomatic index ( GSI ) was examined and histological observations of both ovaries and testes were conducted. The female GSI gradually increased from May, maintained a high level between August and October and then rapidly decreased. The histological observations of the ovary showed that vitellogenesis began from May and developed until September. Spent fish began to be observed in October and all the fish collected in December were spent. There was only one peak in the seasonal change in GSI of males and females in Wakasa Bay. Thus, yellow sea bream spawn only in autumn in Wakasa Bay. Differences in the reproductive cycle and number of spawning seasons were found between the two different latitudinal areas, Wakasa Bay and the East China Sea (low latitudinal area) where the spawning seasons were spring and autumn. An increase in water temperature is an important factor to initiate gonadal maturation (recrudescence) and is terminated by the short day-length in Wakasa Bay.  相似文献   

7.
A study of the reproductive biology of the amberjack, Seriola dumerilii, held in captivity was carried out, describing oogenesis as well as the different stages of the ovarian cycle. Seven stages of oocyte development, as well as oogonia, were distinguished. Cortical alveoli were hardly detectable within the oocyte, as they were small, sparse and contained few mucopolysaccharides. It is suggested that their role in the fertilization process might be less important than in other teleost species. Fish aged 3 and 4 years were found to be sexually immature, with ovaries containing only previtellogenic oocytes. Vitellogenesis started in December in fish aged 4 + years. Late-developing ovaries showing deposition of yolk protein granules were found at the end of the 5th year of life (May) in specimens measuring 80.0 ± 3.5 cm standard length. This should be regarded as the minimum size at which sexual maturity is reached in S. dumerilii. Final vitellogenesis and oocyte maturation were, however, inhibited in captivity, and extensive follicular atresia took place as the natural spawning season approached. It is suggested that insufficient gonadotrophic stimulation because of confinement stress may be the cause of failed maturation and spawning in this species under culture conditions.  相似文献   

8.
Triploid female fish show impaired gametogenesis and are unable to produce viable offspring. The reproductive physiology of artificially-induced triploid female salmonids has been well described up until the time of first sexual maturation in diploids, but few reports exist for older triploids. This study reports the influence of triploidy on growth, ovarian development and reproductive endocrinology among three age classes of female brook trout (Salvelinus fontinalis) in comparison to sibling diploids. Triploids were larger than diploids for most of the study period, but the difference was statistically significant only during maturation and spawning of 2+ diploids. Plasma estradiol-17 (E2), testosterone (T) and vitellogenin (VTG) levels in triploids were generally lower than in diploids, and VTG was the only parameter to show seasonal fluctuations resembling those of diploids. Triploids showed significantly lower GSI and total oocyte number than diploids of similar age, and only half of all triploids sacrificed during the study (n=56) had developing oocytes in their ovaries. At age 3+, 13 of 19 triploid females had oocytes at various stages of development, including perinucleolar, yolk vesicle and yolk globule stages. In addition, three of these fish had collectively produced 72 mature stage oocytes. Thus, whereas diploid brook trout can produce mature oocytes as two-year-olds, triploids cannot do so until four years of age, with the number of mature oocytes being greatly reduced.  相似文献   

9.
Cues from the moon influence synchrony in growth, feeding, migration, behaviour and reproduction of many reef fishes. Compared with comprehensive studies on the annual and daily activities of fish, few physiological studies have paid attention to the importance of lunar cues in reproductive activities. We review mutual and interesting relationships between fish reproduction and environmental changes induced by the moon, with particular emphasis on the reproductive activity of the rabbitfishes (Siganidae). Rabbitfish species exhibit, in nature, a definitive reproductive season, which differs among the tropical areas. During the reproductive season, synchronous spawning of rabbitfish is associated with a particular lunar phase. The lunar phase used by the respective species is similar in different regions on the earth. Histological observations revealed that gonads develop synchronously towards a peak around the spawning lunar phase, after which the gonads return to spent condition. Concomitant with gonadal development, sex steroid hormones were produced under the influence of gonadotropin (GtH). Injections of human chronic gonadotropin (hCG) to the fish that are undergoing active spermatogenesis accelerated testicular maturation. These results suggest that hormonal response in maturing the gonads in rabbitfish is under the regulation of GtH, and that pituitary secretion of GtH according to the lunar cycle accounts for the lunar rhythm in gonadal development. We speculate that the cues from the moon can be recognized by the higher parts of the hypothalamus–pituitary–gonadal axis. Possible relationships between exogenous environmental factors and the lunar‐reproductive rhythm are also discussed.  相似文献   

10.
Oocyte and liver histomorphology of the daubed shanny (Leptoclinus maculatus) from Isfjorden and Kongsfjorden in Svalbard were investigated during three Arctic seasons: summer (July), autumn (October) and winter (April). Three oocyte developmental phases were observed: primary growth phase, secondary growth phase and maturation phase. We observed four different developmental stages: (1) perinucleolus stage with cortical alveolus formation, (2) lipid droplets formation, (3) vitellogenesis stage and (4) maturation. Late maturation stage of oocytes in the ovaries was from the autumn season. Females accumulated lipids in liver (up to 35.2?% dw) and deposited large amounts of lipids into gonads (up to 52.2?% dw) during maturation. Lipid classes in female gonads changed seasonally, with relative increase in cholesterol during summer and depletion of storage lipids (triacylglycerols and wax esters/cholesterol esters) during the winter. Lipid composition in liver changed during oocyte development and spawning, as neutral lipids were transferred to developing oocytes during summer to autumn. During winter, storage lipids were depleted during starvation. Based on the increase in gonadosomatic index (GSI) with length and observed maturation stages, females seem to mature at a length of about 125-130?mm. The GSI and hepatosomatic index of large females sampled in autumn (September-October) were significantly higher than for females in late winter (April) and spring (May). These results indicate that spawning takes place during winter in Isfjorden and that energy reserves stored in the liver are utilized by females during gonadal development and reproduction.  相似文献   

11.
The present study investigated the external and histological changes in the ovary and measured the gonadosomatic index (GSI) and hepatosomatic index (HSI) during the re‐maturation of the Chinese mitten crab Eriocheir sinensis. The results show that the ovarian re‐maturation cycle of this crab species can be divided into four stages, i.e. Stage I: the ovary had an X shape and appeared milky white or with a mottled buff colour, and the dominant gametocyte at the stage were oogonia (OG, 28.3%) and previtellogenic oocytes (PR, 31.6%); Stage II: the ovary appeared light yellow or tan in colour, dominated by endogenous vitellogeic oocytes (EN, 69.3%). The yolk globules of unreleased mature oocytes (MO) from the previous spawn were absorbed, leaving many vacuoles in the retrogressing MO; Stage III: the ovary appeared crimson red or deep purple, and although the main type of gametocyte was exogenous vitellogenic oocytes (EX), near‐mature oocytes (NO) could also be found in the late phase of the ovarian development stage; Stage IV: the ovary was ripe and filled with MO that contained large yolk globules. During the period of the second ovarian maturation cycle, the GSI increased significantly from the time just after the first spawning (P<0.01). However, although HSI appeared to decrease within days after spawning (DAS), no significant correlation was found between GSI and HSI or between HSI and DAS (P>0.05). Furthermore, the final GSI and the volume of MO of E. sinensis during the second maturation cycle were drastically lower than those of the first maturation cycle.  相似文献   

12.
Lunar-related spawning in honeycomb grouper, Epinephelus merra   总被引：1，自引：0，他引：1  
Lunar-related spawning in honeycomb grouper was investigated by histological and behavioral analyses. Ovarian development and spawning of the fish were related to lunar periodicity. And also the fish migrated to out side of the reef area and spawned for a few days after the full moon.  相似文献   

13.
半滑舌鳎卵巢发育的组织学和形态数量特征研究   总被引：5，自引：2，他引：3       下载免费PDF全文
采用组织学方法系统研究了人工养殖条件下半滑舌鳎亲鱼卵巢的组织发育周年变化特征.结果表明,卵母细胞发育可分为6个时相,卵巢发育分为6期.卵巢不同发育时期都由不同类型的卵母细胞组成,半滑舌鳎为非同步分批多次产卵类型.周年发育过程中,6月龄前的鱼卵巢发育处于第Ⅰ期;9～12月龄卵巢可发育至第Ⅱ期;12月龄半滑舌鳎性腺可发育达到Ⅲ期,并一直保持至24月龄.3龄雌鱼达到性成熟,卵巢可发育至第Ⅳ期;随着水温和光周期的调控,卵巢发育进入成熟期(Ⅴ期),发生水合现象是卵母细胞成熟并准备排卵的信号;产卵结束后卵巢退化至第Ⅵ期,排出的卵母细胞退化吸收,以Ⅲ期卵巢越冬后,卵巢退化至Ⅱ期并持续至下一个繁殖周期.人工养殖条件下,卵巢内存在卵母细胞闭锁现象.性腺周年发育过程中,性腺指数(GSI)在性腺达到成熟期时达到峰值,产卵结束后性腺快速退化,GSI值各月份差异显著(P<0.05),亲鱼性腺重量在卵巢发育成熟过程中一直处于生长状态.亲鱼肝脏指数(HSI)在产卵前7～8月份(性腺达到成熟期前30 d左右)达到最大,表明7～8月份是性腺进行卵子发育、卵黄能量储备的重要时期,亲鱼在产卵前通过积极摄食储备体内能量,肝脏在卵母细胞卵黄积累方面具有重要的生理作用.肥满度(CF)值在繁殖盛期10～11月份达到最大,表现出与GSI类似的变化趋势.  相似文献   

14.
A histological study was made of the reproductive cycle of captive sharpsnout seabream Diplodus puntazzo during the 3rd year of life. All specimens contained both ovarian and testicular tissue. Ovarian tissue prevailed in 64 out of 120 fish sampled throughout one year. The ovary underwent a long resting phase from October to August, during which time it contained oogonia, primary growth phase (PGP) and occasional yolk vesicle stage oocytes. Intense ovarian development took place in September leading to the formation of advanced vitellogenic oocytes. Final maturation and spawning were not achieved in any of the fish. The testicular area in the predominantly female gonads contained only spermatogonia and was found to be histologically normal in 76% of individuals, but severely regressed in the remaining fish. The testicular portion was found to be dominant in 56 out of 120 fish sampled throughout one year. These underwent a resting phase from November to July, a maturing/pre-spawning phase in August, and a spawning phase with spontaneous sperm release in September to October, as in the natural environment. The ovarian portion in the functional male gonads contained only oogonia and oocytes which did not develop beyond the perinucleolus stage at any point during the reproductive cycle. Apart from the pre-spawning/spawning phase, during which the gonadosomatic index (GSI) was comparable in the two groups, the GSI values were approximately ten-fold higher in those fish in which the ovary predominated than in those in which the testis predominated.  相似文献   

15.
ABSTRACT:   Final oocyte maturation and ovulation of captive chub mackerel Scomber japonicus with fully yolk-accumulated oocytes were induced by a single injection of human chorionic gonadotropin. Reproductive parameters, including spawning frequency and batch fecundity, which are required to estimate spawning biomass in pelagic fish by the daily egg production method, were analyzed. Germinal vesicle migration (GVM) occurred at 18–24 h post-injection, and the hydration and ovulation of oocytes were completed at 30 and 36 h post-injection, respectively. The results of the maturation process suggest that fish with GVM-stage ovaries captured in the daytime from the field are capable of spawning on the night following their capture. The oocytes used in the oocyte size-frequency distribution method for batch fecundity estimates should be at late GVM and more advanced stages. The results of sequential artificial insemination showed that the quality of ovulated eggs held in the ovarian lumen rapidly deteriorated as time progressed after ovulation. This indicates that the fertilization window for the ovulated eggs of chub mackerel lasts only a few hours, and spawning behavior should be performed within a few hours after ovulation in the wild population.  相似文献   

16.
Oogenesis in the common Japanese conger Conger myriaster   总被引：1，自引：0，他引：1  
TOMOKO  UTOH  NORIYUKI  HORIE  AKIHIRO  OKAMURA  YOSHIAKI  YAMADA  SATORU  TANAKA  NAOMI  MIKAWA  ATSUSHI  AKAZAWA  HIDEO P  OKA 《Fisheries Science》2003,69(1):181-188
ABSTRACT:    We investigated the process and characteristics of oogenesis in the common Japanese conger Conger myriaster . Young fish caught in November 1996 were reared for use in this experiment. Fish were sampled monthly from December 1997 to August 1998. Some were injected with human chorionic gonadotropin to stimulate ovarian maturation from May to August 1998. Oocytes from the chromatin nucleolus stage to the secondary yolk globule stage were obtained from non-hormone-treated fish; those of more advanced stages were obtained from hormone-treated ones. We divided oocyte development into eight stages from the chromatin nucleolus stage to the maturation stage. The yolk vesicle stage was not separated because yolk vesicles began to appear just after appearance of yolk globules. Oocyte, oil droplet, yolk globule and nucleus diameters all increased concomitant with oocyte development. Oil droplet and yolk globule diameters increased remarkably at the maturation stage. However, zona radiata thickness peaked at the secondary yolk globule stage, decreasing gradually thereafter. Increased gonadosomatic index was related to oocyte development as found in European and Japanese eels receiving hormone treatment to mature. The present study is the first report describing oogenesis characteristics in congrid eels. It indicates that oogenesis is almost identical to that of other anguillid eels.  相似文献   

17.
Ovarian developmental stages and serum steroid hormone levels were examined at six different times of day (0100, 0600, 1000, 1300, 1600, 2000 h) in a marine teleost, the Japanese whiting Sillago japonica, which has an asynchronous-type ovary containing oocytes at various stages of development and spawns every day during a period ranging up to three months. The largest oocytes in the ovaries at the active vitellogenic or post-vitellogenic stages were found between 0100 and 1300 h. Oocyte maturation indicated by germinal vesicle breakdown (GVBD) occurred at 1600 h, and ovulated oocytes were observed in the ovaries collected at 2000 h. These processes were accompanied by a significant daily change in serum steroid hormone levels. The serum level of estradiol-17β showed a peak in fish with mature oocytes sampled at 1600 h. In these fish, the second-largest oocytes in the ovaries were at the initial stage of vigorous vitellogenesis, the secondary yolk stage. Therefore the highest level of serum estradiol-17β was considered to be due to the second-largest oocytes. Testosterone levels remained low and constant throughout the experimental period. The serum levels of 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-diOHprog) peaked at 1600 h at which time all fish had mature oocytes. These results indicate that the Japanese whiting possesses a diurnal rhythm of oocyte development including vitellogenesis, oocyte maturation and ovulation, and further suggest that daily cycles in oocyte growth and maturation which simultaneously take place in an ovary are regulated by diurnal secretions of estradiol-17β and the maturation-inducing steroid, 17α,20β-diOHprog.  相似文献   

18.
Detailed knowledge of the reproductive characteristics of fish in tropical areas is currently lacking. We have performed a histological study of the reproductive aspects of Sphaeramia orbicularis, a tropical fish found on the Weno Islands of the Chuuk Lagoon, Micronesia, and further estimated the gonadosomatic indices (GSI) of this fish. The sex ratio was approximately 1:1. The standard length of males and females at 50% maturity was 49.0 and 46.9 mm, respectively. Histological observation of S. orbicularis ovaries and testes revealed that the fish exhibits multiple spawner characteristics, including coexistence of primary yolk stages, migratory nucleus or mature stages, and asynchronism of the spermatogenesis process. Monthly variations in the GSI and gonadal maturity stages demonstrated that reproductive activity occurs throughout the year. The findings in this study provide important information on the spawning activity and season of S. orbicularis in Micronesia.  相似文献   

19.
SUMMARY: Seasonal changes in the percentage of mature female Metapenaeopsis dalei were studied histologically, and the annual cycle of maturation and spawning of this species was discussed. Specimens were collected at night by a beam trawler in Tosa Bay (33°N, 133°E) during the period from April 1995 to March 1996. All individuals had a gonado somatic index [ GSI = 100 (gonado weight/body weight)] of higher than 8, and 66.7% of those individuals with a GSI of 6–8 had oocytes in the late phase of the prematuration stage after germinal vesicle shrinking and migrating to the margin of the oocyte or had oocytes in the maturation stage. Such individuals with developed oocytes appeared in April, June, July, August, October, November and March. Individuals with a GSI above 6 appeared throughout the year, except during September and February. Individuals with ovulated oocytes were sampled in March when the water temperature near the bottom depths was lowest (15.4°C) during the year, being similar to February (15.1°C). These facts indicate that maturation occurs all year-round and suggests that spawning in the Metapenaeopsis dalei population in Tosa Bay occurs all year-round. This is the first report of year-round maturation in penaeid shrimps in Japanese waters.  相似文献   

20.
The reproductive biology of the Blackfin snook Centropomus medius was studied to expand our current knowledge on its aquaculture potential. From April 2001 to November 2002, 301 females and 193 males were captured. A 1:1.6 (male:female) ratio was found. Gonadosomatic (GSI) and hepatosomatic (HSI) indices suggested that the spawning period (SP) extended from September to November, with peak spawning activity in September (GSI=0.98% and HSI=0.7%). The period of pre‐gametogenesis extended from January to June. During the post‐SP in December, 90% of oocytes were pre‐vitellogenic and 10% were atretic. Histological analysis of gonads (haematoxylin–eosin, Sudan black B, Alcian blue PAS, Cleveland Wolfe) showed five stages of oocyte development, each occurring at a characteristic range of oocyte diameters (μm): (I) pre‐vitellogenic (25–55); (II) cortical alveoli (56–250); (III) vitellogenic (251–340); (IV) maturation (341–645) and (V) atretic (21–100). Five reproductive stages were identified for testis morphology: (I) regressed; (II) early maturation; (III) mid‐maturation; (IV) full maturation and (V) regression. The type of ovarian development in C. medius was identified as a group synchronous.  相似文献   

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