细鳞鲴卵巢发育的组织学观察

采用组织学方法对细鳞鲴卵巢周年变化和卵母细胞发育进行了观察研究。结果表明,细鳞鲴卵巢发育分为6个时期,卵母细胞发育分5个时相,从第Ⅲ时相卵母细胞开始表现出种的特异性。3月卵巢处于产前发育阶段,4-7月为繁殖期,5-6月为繁殖盛期,8月卵巢基本修整完毕,9-10月为Ⅱ′期发育,11月至翌年2月以Ⅲ期卵巢越冬。细鳞鲴的产卵方式为短期分批同步产卵类型,在一个生殖周期内一般产卵2~3次。     

The reproductive biology of the baby clam, Marcia opima, from two geographically separated areas of India

A study of the reproductive cycle of the baby clam, Marcia opima (Gmelin) was conducted at two sites along the southeast (Tuticorin Bay) and southwest (Ashtamudi estuary) coast of India from December 1998 to January 2000. Histological evidence showed that baby clam from both the sites showed two spawning seasons. First spawning season was recorded from May to July in the southeast coast. In the southwest coast, the first spawning season was observed through March to May. A second spawning season from September to December was recorded in both the coasts. In the southeast coast, minimum and maximum condition indices were obtained in January 2000 and April 1999 respectively and decreased from May to June and November to January, signifying the two spawning periods. Most of the animals were either in spent or indeterminate gonadal stage from May to August and November to January indicating the active spawning during that months in the southeast coast.     

钝缀锦蛤繁殖周期和胚胎发育

2013年8月至2014年7月,采用组织学和实验生态学方法对钝缀锦蛤(Tapes conspersus)的性腺发育、生殖周期、肥满度、胚胎和幼虫发育进行了研究。结果显示,钝缀锦蛤性腺发育以1年为1个周期,性腺发育过程可分为增殖期、生长期、成熟期、排放期和休止期5个时期;繁殖期在每年10月至翌年3月,繁殖盛期为3月、10月和11月(水温20.3~24.6℃),分批产卵。8月肥满度最高,为33.43%;4月最低,为18.31%。钝缀锦蛤卵径为70~80μm;在水温24~26℃、盐度28~32条件下,受精卵经16 h左右发育为D形幼虫;初孵D形幼虫大小为90~110μm,浮游幼虫经7~8 d培育进入附着变态期,此时壳长为210~230μm,再经4~5 d发育变态为稚贝。本研究为钝缀锦蛤的人工繁育及种质资源保护和利用提供了基础资料。     

Maturation and spawning of the small penaeid shrimp Metapenaeopsis dalei in Tosa Bay, Pacific coast of southern Japan

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.     

The onset of spawning in the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters and its implications for management

Abstract The spawning periodicity of silver pomfret, Pampus argenteus (Euphrasen), was investigated against a background of conflicting evidence on the onset of spawning in this species. Contrary to the existing view that silver pomfret in Kuwait waters begin to spawn in March–April, evidence is presented that indicates a delay in spawning until May. Only an insignificant level of spawning takes place in April which, from the management point of view, may be ignored. The species has a prolonged spawning period extending from May to August in females, although the males mature in April and ripe specimens are encountered in monthly samples until September. There are two spawning peaks, the first one in May and the second in August.     

Reproductive biology of the commercial sea cucumber <Emphasis Type="Italic">Holothuria spinifera</Emphasis> (Echinodermata: Holothuroidea) from Tuticorin,Tamil Nadu,India

The annual reproductive cycle of the commercial sea cucumber Holothuria spinifera was studied in Tuticorin, Tamil Nadu, India, from September 2000 to October 2001, by macroscopic and microscopic examination of gonad tubule, gonad index and histology of gametogenic stages, to determine the spawning pattern. The gonad consists of long tubules with uniform development. It does not confirm the progressive tubule recruitment model described for other holothurians. The maximum percentage of mature animals, gonad and fecundity indices, tubule length and diameter, with the observations on gonad histology, ascertained that H. spinifera had the peak gametogenic activity during September and October 2001 followed by a prolonged spawning period from November 2000–March 2001.     

太平洋牡蛎2龄贝的生长

通过１９９８扑３月 １２月对太平洋牡蛎２龄贝生长进行测定得出：壳高在４～６月初生长最快；７月、１２月为出肉率最高时期；７月末８月初为２龄贝产卵期。     

Reproductive condition of the pearl oyster, Pinctada imbricata, Röding, in Port Stephens, New South Wales, Australia

In an investigation of the potential for pearl production in New South Wales (NSW), Australia, changes in the physical and reproductive condition of the pearl oyster, Pinctada imbricata, were monitored for over 2 years. Using wild oysters gathered from close to the southern extent of the species' range in Port Stephens, NSW, a series of macroscopic and histological observations were made. Reproductive activity in P. imbricata was greatest from late spring to early autumn with oysters in poor reproductive condition during winter. Peaks in reproductive indices occurred in November 1998, March 1999, December 1999 and April 2000. Four indices of physiological condition were used: shell growth, byssal attachment, mantle thickness and mucoprotien layer. With the exception of the thickness and extent of the mucoprotein layer, these indices either showed little variation or the variation that occurred was not related to seasonal or reproductive changes. Changes in the mucoprotein layer were correlated with water temperature and suggest that this layer is metabolized during periods of high demand such as during gonadogenesis. Collectors deployed at two sites in Port Stephens demonstrated that spatfall occurs largely in the months of December and January following the spring and early summer peaks in reproductive activity (November 1998 and December 1999). Spatfall was not observed following the autumnal peaks (March 1999 and April 2000) in reproductive activity. Overall, reproductive patterns in P. imbricata are poorly suited to spat supply in Port Stephens. Farmers require spat in early spring (September) to allow maximum use of the ‘growing’ season (September–May). Reproductively capable oysters are not available from the wild until September and quantity of natural spatfall is too variable and occurs too late in the season (December–January). As a result, oysters are being conditioned in the hatchery in July, spawned in August and spat are supplied to farmers in mid September.     

Seasonal gonadal changes in the clam, Paphia laterisulca

The seasonal gonadal changes in the edible clam, Paphia laterisulca, from the Kalbadevi Estuary at Ratnagiri were studied for the period from May 1972 to April 1973 with the help of fresh gonad smears and histological study. The observations of gonad smears revealed the probable commencement of spawning between September and April from the occurrence of spent gonads. Male and female clams were present in almost equal numbers throughout the year.Histological details revealed that the clam P. laterisulca has a prolonged spawning period extending from mid-September to the end of March with two peaks, the first in October–November and the second in February–March. Lysis of the ripe gametes in both sexes for 2.5 months preceding spawning was observed. The second spawning peak was followed by regression in the gonads.Active gametogenesis was observed in May and June (33.5°C and 30.0°C), and again in December and January (21.5°C and 26.0°C) in clams that had spawned during the first spawning peak.The spawning stimulus in Paphia laterisulca appeared to be the sudden increase in salinity (from 4.1 to 22.5‰) in September in the Kalbadevi Estuary.     

Reproductive biology of Venus clam Gafrarium tumidum (Roding, 1798) from Southeast coast of India

The reproductive biology of tumid venus clam Gafrarium tumidum (Roding) was studied in detail from the Southeast coast of India. Sample size ranged from 10.3 to 41.3 mm. Sexes are separate but not differentiated externally. Annual sex ratio male:female (M:F) deviated significantly from the 1:1 ratio with females dominating. Based on ova diameter progression of gonad smear and histology, four and two maturity stages of gonads were differentiated in female and male clams, respectively. Peak spawning was observed during November and a minor one in April. The monthly average condition index based on wet/dry flesh weight ranged from 7.24 (November) and 14.14 (September) and 8.82 (October) and 14.38 (August), respectively. The condition index observed by both the methods is comparable and corresponds with the spawning season. Water content observed for male and female clams varied negligibly and showed positive correlation with spawning period. Size at first maturity was estimated to be 22.3 mm.     

北部湾鲔(Euthynnus affinis)的摄食习性及其随生长发育的变化

基于2008年9月-2009年9月在北部湾逐月采集的435尾鲔(Euthynnus affinis)生物学数据,对鲔生长、摄食习性及其随生长发育的变化进行了分析。结果显示,北部湾鲔属于广食性鱼类,主要摄食中上层小型鱼类,另外还包括底栖鱼类、甲壳类和头足类等。少鳞犀鳕(Bregmaceros rarisquamosus,45.50%)、青带小公鱼(Stolephorus zollingeri,11.81%)和长颌棱鳀(Theyssa setirostris,5.89%)为鲔优势饵料生物种类,并且其主要饵料生物种类随采样时间的不同而有所差异,如金色小沙丁鱼(Sardinella aurita,1月)、未能鉴定鱼类(4-7月)、长颌棱鳀(8月)、条鲾(Leignathus riviulatus,9月)、青带小公鱼(10月)、少鳞犀鳕(11–翌年3月)。体长小于340 mm的鲔个体随体长的增加其平均摄食饵料生物的个数与质量呈上升趋势;体长在341-520 mm范围内的鲔个体,随着体长的增加其平均摄食饵料生物的个数与质量总体上呈现下降趋势。鲔产卵主要集中在4-8月,根据雌性GSI(性腺成熟度指数)分析,具有两个产卵高峰期(6月、8月),产卵高峰期和中上层水温的升高有密切关系。鲔的摄食强度在性腺发育过程中波动较大,但在产卵期间,其摄食强度并未明显降低。     

The Potential for Developing Controlled Breeding in the Chilean Oyster

International interest in the commercial aquaculture of the Chilean oyster, Tiostrea chilensis, is frustrated by an inability to artificially control their unusual breeding behaviour. The manipulation of breeding in this oyster will rely on a better understanding of its gametogenic cycle. Consequently, the gametogenesis of a wild population of highly fertile Chilean oysters from northern New Zealand was studied over three years to assess the potential for artificially controlling oyster breeding for aquaculture. The population was mostly comprised of simultaneous hermaphrodite oysters that generally followed annual cycles of gametogenesis. Oysters spawned as males throughout each year with increased spawning from November to February (ie., austral spring and summer). Ova were abundant throughout the year, although female spawning increased during spring. The unpredictable spawning of ova among individual oysters and the strong possibility of self-fertilization create difficulties for the development of controlled breeding in this species. If the full aquaculture potential of T. chilensis is to be realized, further research should be directed at identifying the factors involved in controlling female maturation, spawning and fertilization.     

Reproductive biology of a tropical catfish, Mystics nemurus Cuvier & Valenciennes, in Chenderoh reservoir, Malaysia

Abstract. The reproductive biology of a popular and abundant freshwater catfish, Mystus nemurus Cuvier & Valenciennes, was examined, including sex ratio, gonadosomatic index, ova diameter and fecundity. The numerical ratio of male to female was 1:1.06 and was not significantly different (P > 0.05). Mean female gonadosomatic indices (GSI) in April and September corresponding to north-east and south-west monsoons were significantly different (P < 0.05) from the dry season (May, June, July and August). Thus the apparent GSI maxima in April and September were indicative of peak spawning period. However, there were no significant differences (P > 0.05) in the fluctuation of the measure of GSI except for those in the dry months, which probably suggested the existence of a protracted breeding season. Mean male GSI in February and November were similarly significant (P < 0.05) to the dry season, although not statistically different (P > 0.05) from those of January, March, April, July, August, October and November. This was probably attributable to an extended breeding period with spawning peaks in February and November corresponding to early and late monsoons. The aseasonal reproduction is common in tropical fishes. GSI were positively correlated with rainfall and water level fluctuations. Fecundity varied from a minimum 6900 to a maximum 93510 in specimens with total lengths of 34.8cm and 45.0cm respectively. Fecundity was found to increase linearly with length and weight and was significantly different (P < 0.05) from them.     

Analysis of germ cell proliferation, apoptosis, and androgenesis in the Lake Van fish (Chalcalburnus tarichi) during testicular development

In the present study, the testis histology, gonadosomatic index (GSI), germ cell proliferation and apoptosis, and the plasma 11-ketotestosterone (11-KT) and testosterone (T) levels of male Chalcalburnus tarichi were analyzed. According to the histological examinations of the specimens that were caught between February 2009 and January 2010, three testicular stages were determined. Those stages were as follows: (1) recrudescence or prespawning (July–April), (2) spawning (May–June), and (3) postspawning (July). It was observed that the GSI increased gradually, starting from the recrudescence stage, and it reached peak values at the spawning stage, while the lowest values were in the postspawning. Germ cell proliferation in the testis was detected using a proliferating cell nuclear antigen (PCNA), and germ cell apoptosis was detected by transferase dUTP nick end labeling staining. The germ cell PCNA and apoptosis index values were calculated. It was indicated that germ cell proliferation was observed in all of the testicular stages. The highest germ cell PCNA index (PI) levels were detected in July, August, and September, which then dropped in October and stabilized between February and April. The lowest PI values were detected in the spawning stage (May–June). Germ cell apoptosis was observed in all of the months, and the highest apoptotic index values were detected in August, September, October, May, and June. Plasma 11-KT and T levels were at their highest levels in May and June, and it was detected as stabile in the other months. There was a correlation between GSI, PI, and plasma androgen levels. In conclusion, the present data illustrate testicular development stages for C. tarichi and show changes in the level of GSI and sex steroid biosynthesis through spermatogenesis.     

Seasonality of reproduction in male spotted murrel <Emphasis Type="Italic">Channa punctatus</Emphasis>: correlation of environmental variables and plasma sex steroids with histological changes in testis

The present study was undertaken to develop a comprehensive understanding of how environmental cues and sex steroids relate with cyclic changes in spermatogenesis in freshwater spotted snakehead Channa punctatus that is nutritious and economically important. The seasonal histological changes in testis and annual profile of gonadosomatic index (GSI) of C. punctatus delineated the testicular cycle into four phases: regressed (December–March), preparatory (April–June), spawning (July and August) and postspawning (September–November). Among environmental variables, correlation and regression analyses exhibited an important relationship between photoperiod and testicular weight while role of rainfall was seen confined to spawning. The seasonal profile of plasma sex steroids when correlated with cyclic changes in spermatogenesis in spotted snakehead, testosterone (T) seems to be involved in controlling the major events of spermatogenesis from renewal of stem cells to spawning of spermatozoa. Another important androgen prevalent in teleosts, 11-ketotestosterone (11-KT), was high during preparatory phase, suggesting that 11-KT in addition to T plays an important role in progression of spermatogenesis and spermiation in C. punctatus. However, 11-KT was not seen to be associated with milt production and release of spermatozoa during spawning. Plasma profile of estradiol-17β (E₂) during different reproductive phases revealed the involvement of E₂ in repopulation of stem cells during postspawning phase and in maintaining quiescence of testis during regressed phase.     

北海珍珠养殖区与非养殖区春、秋季磷的形态特征及其相关性

利用2008年9月和2009年4月对北海珍珠养殖区和非养殖区的调查资料,对该海区磷的循环特征及其生态效应进行了分析研究.研究结果表明,该海区磷的储量不高,无论是养殖区还是非养殖区均表现为有机态磷和无机磷含量明显偏低.除颗粒态磷外,所有形态磷均表现为秋季明显高于春季,突出体现了生物释放的补充影响作用.在磷的形态转化上,春...     

Changes in plasma insulin-like growth factor-I levels in the precociously maturing amago salmon, Oncorhynchus masou ishikawai

Seasonal changes in plasma levels of insulin-like growth factor I (IGF-I) in precociously maturing amago salmon (Oncorhynchus masou ishikawai), which matured as 1-year-olds, have been investigated. Profiles of plasma IGF-I levels were compared with changes in growth and maturity, and plasma growth hormone (GH) and thyroxine (T₄) concentrations. The maturity of the fish was determined by calculating the gonadosomatic index; in November, 100% of males and 89% females matured. In both males and females, plasma IGF-I levels increased from March to August, and subsequently, plasma IGF-I levels in the early maturing males and females declined gradually and were maintained at lower levels during the spawning period in November. Plasma GH levels were high in April, and then declined gradually through September. Thereafter, in early maturing fish, a slight increase in plasma GH levels was observed in October and November. No significant changes in plasma T₄ levels were found in the precociously maturing fish. In sharp contrast, plasma IGF-I levels in immature fish remained elevated through September, reaching a peak in October, and then gradually declined in November. In immature females, plasma T₄ and GH levels were elevated in August, reached their maximum in September and then gradually declined until November.     

岩虫的性腺发育和生殖周期

根据性腺发育的组织切片观察，岩虫（Marphysa sanguinea）性腺发育可分为增生期、成熟期、排放期和休止期4个阶段。通过连续两年每月对岩虫性腺组织切片观察可以确定，在山东省乳山海区的岩虫性腺发育为1年1个周期。12月至翌年6月为增生期；7～8月为成熟期；7月下旬至8月为排放期；9～11月为休止期，其中7月下旬至8月中旬为繁殖盛期。岩虫的性腺起源于体腔腹面生殖上皮。生殖细胞发生时不出现滋养细胞。除休止期外，生殖细胞持续发生，成熟时多次排放。雄性生殖细胞形成合胞体（syncytium），精子为原始类型。雌性生殖细胞不形成合胞体，卵母细胞在发育的早期阶段，卵黄发生期问从卵巢（生殖上皮）排入体腔中，并在体腔中发育。卵细胞成熟时，有卵外膜，结构复杂。     

Progress Toward Year-round Spawning of Southern Flounder Broodstock by Manipulation of Photoperiod and Temperature

Reliable methods have been developed for controlled spawning of captive southern flounder, Paralichthys lethostigma, broodstock during their natural winter (December–February) spawning season. From 1999 to 2004, we evaluated the effects of manipulation of photoperiod and temperature on both advance and delay spawning to produce viable embryos throughout the year. Wild‐caught adult broodstock were held in 4.8‐ to 7.0‐m³ controlled‐environment tanks at a sex ratio of approximately 12 females to 4 males. Broodstock were subjected to different artificial photothermal conditioning regimes: extended winter (EW), accelerated (A‐10‐, A‐6‐, A‐4.5‐, and A‐3.8‐mo regimes), and delayed (D‐16‐ and D‐14‐mo regimes), with gradual and abrupt transitions, respectively, from long to short daylengths. Under an EW cycle, fish were exposed to constant short daylengths (10 L: 14 D) after the winter solstice in January. Eighty‐seven natural spawnings from December to April produced 18.3 × 10⁶ eggs, with 20.9% hatching successfully (i.e., overall egg viability). Under an A‐10‐mo cycle, rate of decrease in daylength was accelerated after the summer solstice in July, to reach winter conditions in October. Seven induced spawning trials from October to November produced 897 × 10³ eggs, with 40.4% viability. Under an A‐6‐mo cycle, rate of change of photoperiod was accelerated after the winter solstice in January, to reach winter conditions in July. Three induced spawning trials in July produced 550 × 10³ eggs, with 14.7% viability. Under an A‐4.5‐mo cycle, broodstock exposed to EW from January through April were exposed to an accelerated cycle to reach winter conditions by October. Four induced spawning trials from September to November produced 729 × 10³ eggs, with 28.7% viability. Under an A‐3.8‐mo cycle, broodstock exposed to EW conditions from January through April were exposed to an accelerated cycle to reach winter conditions by September. Five induced spawning trials from September to November produced 510 × 10³ eggs, with 45.9% viability. Under a D‐16‐mo cycle, fish were exposed to a decelerated decline in photoperiod after the summer solstice in July, to reach winter conditions in May, when atretic females were observed. Under a D‐14‐mo cycle, fish were exposed to constant summer conditions from December through mid‐June and then to an abrupt decline in photoperiod to winter conditions in late June. Six induced spawning trials from September to November produced 763 × 10³ eggs, with 13.0% viability. Production of viable embryos was greatest during the extended winter because of abundant natural spawnings. While successful natural spawnings were rare during the fall or summer, viable embryos were produced through induced spawnings during all seasons of the year, with no significant (P > 0.05) differences in egg viability. Extended winter conditions prolonged spawning from 3 to 5 mo. Accelerated (3.8–10 mo) regimes were effective in producing viable embryos from summer through fall, but a minimum of 5 mo was required to complete gonadal recrudescence. While constant long daylengths after the summer solstice delayed gonadal recrudescence, with spawning obtained 2.5 mo after an abrupt reduction to short daylengths, a decelerated decline in photoperiod did not. Artificial control of daylength enabled precise control of gonadal recrudescence and year‐round spawning in southern flounder without adverse effects on the quality of eggs and larvae and will improve availability of seedstock for commercial aquaculturists.     

Growth and gonad development of the tropical black-lip pearl oyster, Pinctada margaritifera (L.), in the Gambier archipelago (French Polynesia)

The growth and reproductive cycle of cultured black-lipped pearl oysters, Pinctada margaritifera (L.), were studied in the Gambier Islands (134°52′ W, 23°07′ S) from September 2002 to August 2003. Temperatures were recorded throughout the year, revealing seasonal temperature variations between 22.3 and 27.8°C. The mean annual chlorophyll a value, as computed from satellite data, was 0.188 ± 0.075 μg L⁻¹. To study growth and reproduction, 720 two-year-old individuals were ear hung on long-lines suspended at a depth of 7 m. Samples were taken twice a month to obtain the following measurements: shell height; wet weight of flesh and total oyster; dry weight of adductor muscle, mantle and visceral mass; and glycogen content. Gonad development was also studied by histology on parallel samples. Growth was relatively fast during the first 6 months of the study: average shell height increased from 89.1 ± 9.1 to 119.7 ± 10.8 mm and total weight from 93.4 ± 24.5 to 155.1 ± 33.6 g, between September and the end of March. Subsequently, from April to August, no significant growth was observed for shell and flesh, while the muscle weight decreased significantly. Condition index (CI), defined as the ratio of wet weight of the visceral mass to shell weight, and histological changes in the gonad revealed 3 significant reproductive events of different intensities. The analysis of correlations revealed a specific effect of the chlorophyll a concentration on the growth of shell and soma, and one of the temperature on tissue glycogen content. This study also showed also that CI could be an efficient indicator of reproductive events in pearl oyster. It thus appears that the development of gonads goes on throughout the year in the Gambier Islands, without any detectable phase of sexual rest.