池塘养殖斑节对虾生长、发育与性成熟

为了解不同养殖条件下斑节对虾的生长、外生殖器发育、性腺发育及性成熟之间的关系,对其养殖进行跟踪调查研究.结果显示:①斑节对虾雌雄外生殖器官发育和头胸甲长呈线性关系;②不同养殖环境条件下,斑节对虾性成熟生物学最小型个体无显著差异.雄性精荚出现的生物学最小型个体为头胸甲长3.1 cm,体长11.1 cm,体质量20.0 g;雄性性成熟个体的头胸甲长3.7 cm,体长13.0 cm,体质量37.0 g.池养雌性斑节对虾的性成熟生物学最小型个体以纳精囊的发育完全(可与雄虾交配)为标志,其最小性成熟个体的头胸甲长4.3 cm、体长15.1 cm、体质量53.0 g,雌性性成熟个体为头胸甲长5.0 cm,体长17.0 cm,体质量75.0 g以上;③池塘养殖斑节对虾性成熟与日龄和养殖环境相关.鱼塭雄虾精荚出现的最早时间为日龄120 d前后,其性成熟日龄约为160 d;池塘养殖雄虾精荚出现的最早时间为日龄150 d前后,其性成熟日龄约为260 d.鱼媪雌虾最早交配发生在日龄165 d前后,性成熟日龄205～236 d,池养雌虾最早交配发生在日龄240～ 280 d,性成熟日龄295～360 d以上.     

池塘养殖黄斑篮子鱼初次性成熟性腺发育研究

研究池养黄斑篮子鱼(Siganus oramin)初次性成熟的性腺发育及季节性变化,可为其全人工繁殖提供基础数据。2019年1—7月,每月取1~+龄黄斑篮子鱼进行解剖取性腺切片,计算性腺成熟系数(GSI)和肝体指数(HSI)。结果显示,实验期间性腺发育可分为Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ5个时期,未发现Ⅰ期性腺。1月全部为Ⅱ期;2月卵巢仍为Ⅱ期,部分精巢达Ⅲ期;3月卵巢约一半发育至Ⅲ期,个别Ⅳ期,精巢主要为Ⅳ期,部分Ⅴ期,能挤出精液;4月GSI最大,精巢基本都为Ⅴ期,卵巢少部分发育成熟,绝大部分停留在Ⅲ、Ⅳ期,少量为Ⅱ期;5月繁殖个体性腺短暂进入Ⅵ期后迅速退化,未成熟个体性腺停止发育并退化;6月性腺退化至Ⅱ期;7月保持Ⅱ期,GSI进一步降低。池养黄斑篮子鱼初次性成熟雌性GSI为1.74‰～133.44‰,雄性GSI为1.06‰～138.51‰,均在3—5月出现一次高峰,HSI与GSI的变化趋势一致,但提前1个月左右达到峰值。黄斑篮子鱼卵巢发育是完全同步型,为一次产卵鱼类,繁殖期为3月底至5月初。     

黑龙江水系(中国)大麻哈鱼生物学特征分析

2010和2011年在黑龙江和乌苏里江生殖洄游群体中采集了571尾大麻哈鱼(Oncorhynchus keta Walbaum)样本,进行了鳞片观察和生物学测定。根据退算叉长,采用Logistic生长方程拟合大麻哈鱼叉长的生长,并计算了生长速度和加速度。结果表明,大麻哈鱼3龄前生长速度较快,以后逐渐变慢。对3+龄大麻哈鱼生长分析表明,在1.372和1.492龄时,雄、雌个体生长速度最快,而在2.674和2.823龄时生长加速度最低,和性成熟开始时期相吻合。利用逻辑斯蒂拟合方程估算了大麻哈鱼50%个体初次性成熟叉长(L50),雄性为46.19 cm,雌性为47.95 cm,ARSS分析表明雌雄差异显著(P<0.05),对应的50%初次性成熟时间T50分别为2.00和2.15。通过大麻哈鱼生长分析,认为应将50%初次性成熟叉长作为资源管理的重要生物学指标。黑龙江大麻哈鱼雌性个体GSI和绝对繁殖力均与叉长呈显著正相关(P<0.05),而雄性个体上述指标均与叉长呈显著负相关(P<0.05)。黑龙江雌性和雄性大麻哈鱼GSI与叉长相关关系的回归方程分别为:y=0.578x–18.225(R2=0.441);y=–0.090x+8.852(R2=0.423)。黑龙江群体性腺发育程度高于乌苏里江群体,乌苏里江群体性腺发育的不一致性导致了GSI和叉长的相关关系不显著。     

象山港黄姑鱼的繁殖生物学

依据2011年10月²012年9月每月中旬在象山港水域以桁杆拖虾网采集的黄姑鱼(Nibea albiflora)样本,分析了该水域黄姑鱼的年龄结构、性比、初次性成熟体长以及卵径分布等繁殖生物学特征,旨在丰富黄姑鱼的基础生物学研究,为象山港黄姑鱼的资源修复和保护管理提供科学依据。整个调查期间,共采集到黄姑鱼样本483 ind,体长范围为822012年9月每月中旬在象山港水域以桁杆拖虾网采集的黄姑鱼(Nibea albiflora)样本,分析了该水域黄姑鱼的年龄结构、性比、初次性成熟体长以及卵径分布等繁殖生物学特征,旨在丰富黄姑鱼的基础生物学研究,为象山港黄姑鱼的资源修复和保护管理提供科学依据。整个调查期间,共采集到黄姑鱼样本483 ind,体长范围为82³58 mm。研究结果表明:象山港水域黄姑鱼种群年龄结构简单,主要由0+龄和1+龄鱼组成,分别占32.09%和62.32%,而其它年龄组个体较少;其雌、雄比例接近于1∶1;雌、雄个体的初次性成熟体长L50分别为196.3 mm和190.1 mm;繁殖群体由1+龄和2+龄个体组成;在繁殖期间,1+龄鱼中52.74%的个体性腺发育已成熟,2+龄鱼中93.75%为性成熟个体。通过对性腺指数和雌性个体性腺发育各期所占比例的月变化分析,可知黄姑鱼的产卵时间为5358 mm。研究结果表明:象山港水域黄姑鱼种群年龄结构简单,主要由0+龄和1+龄鱼组成,分别占32.09%和62.32%,而其它年龄组个体较少;其雌、雄比例接近于1∶1;雌、雄个体的初次性成熟体长L50分别为196.3 mm和190.1 mm;繁殖群体由1+龄和2+龄个体组成;在繁殖期间,1+龄鱼中52.74%的个体性腺发育已成熟,2+龄鱼中93.75%为性成熟个体。通过对性腺指数和雌性个体性腺发育各期所占比例的月变化分析,可知黄姑鱼的产卵时间为5⁷月,繁殖盛期为67月,繁殖盛期为6⁷月。各月黄姑鱼的肝脏指数和肥满度均存在明显差异,且与性腺指数呈相反趋势变化。黄姑鱼卵径分布具有2个明显波峰,说明黄姑鱼在一个繁殖期内可进行多次产卵,属于短期分批产卵类型。研究显示,象山港黄姑鱼1龄鱼中性成熟个体的比例较高,开始呈现出繁殖群体低龄化和小型化的趋势,种群资源亟需保护。     

鄱阳湖区黄鳝体长、体重与性比关系初步研究

通过对不同季节在黄鳝市场随机购得的569尾黄鳝体重、体长测量及解剖取性腺观察鉴定性别,统计、分析得出:569尾黄鳝雌性占76.8%,间性占6.5%,雄性占16.7%.春季122尾黄鳝中雌性占85.2%,间性2.5%,雄性12.3%;夏季95尾黄鳝中,雌性占84.2%,间性8.4%,雄性7.4%;秋季231尾黄鳝中,雌性68.4%,间性8.2%,雄性23.4%;冬季121尾黄鳝中雌性78.5%,间性5.8%,雄性15.7%.体长25 cm以下全为雌性,未见雄性;体长25～30 cm,雌性:间性,为1:0.017;初步认为体长30 cm左右为性逆转的起点;体长30～50 cm是间性黄鳝出高峰期,但50 cm以上仍有部分雌性个体.40cm范围以下雌性占多数,45 cm以上雄性占多数.体重25 g以下个体很少见到性转化个体,雌性:间性,为1:0.012;初步认为体重25 g左右为性逆转的起点.25～150 g是间性黄鳝出现高峰期,但黄鳝体重150 g以上仍有部分雌性个体.黄鳝人工繁殖选择野生黄鳝规格为体重75 g以下,体长40cm以下,可基本保证雌鳝占大部分;黄鳝体重75 g以上,体长45cm以上,可基本保证雄鳝占大部分.     

恒温高温调节对赤点石斑鱼幼鱼的生长、性腺发育以及gnrh、fshβ和lhβ基因表达的影响

为了解恒定高温对赤点石斑鱼(Epinephelus akaara)生长和繁殖的影响, 以孵化后120~420 日龄的幼鱼为研究对象, 对性腺发育以及与繁殖相关的基因gnrh、fshβ和lhβ表达进行了研究。对照组为自然水温(13.2~27.1 ℃)饲养, 实验组为26 ℃恒温饲养。每隔30 d或40 d采样1次, 比较两组中鱼的体长、体重、性腺指数(GSI)、性腺发育情况以及gnrh、fshβ和lhβ基因表达的差异。结果表明, 从240日龄开始, 实验组鱼的体长和体重均显著高于对照组(P<0.05)。实验结束时, 实验组体长约为对照组的1.3倍, 体重约为对照组的2倍。对照组GSI一直维持在0.25%以下的低值, 实验组GSI在330日龄前处于0.4%以下, 但在360日龄时出现GSI 1%以上的个体。在360、390和420日龄的个体中, 实验组GSI显著高于对照组(P<0.05)。实验结束时, 对照组中未检测到具有卵黄形成期卵母细胞的个体, 但实验组在330、360和390日龄出现了具有卵黄成熟期卵母细胞的个体。对照组和实验组间幼鱼脑中gnrh基因表达在各年龄段均无显著性差异(P>0.05), 但脑垂体中fshβ表达在360、390和420日龄, lhβ在390和420日龄时, 实验组均显著高于对照组(P<0.05)。研究表明, 26 ℃恒温调节不仅能促进赤点石斑鱼幼鱼体长、体重和GSI的增加, 同时也能显著提高脑垂体中fshβ和lhβ基因含量, 从而加速性腺发育成熟。     

繸鳚繁殖生物学特性

2015年4月至2016年4月在黄海海域的大连市旅顺口区盐场地区逐月采集繸鳚样本350尾,采用常规生物学测定等手段,研究了繸鳚的繁殖生物学。试验结果表明,繸鳚为一次性产卵鱼类,成熟个体具有第二性征;雌雄最小性成熟年龄为2龄,雌性性腺指数在10月达到最高值;雄性在9月达到最高值;其个体绝对繁殖力为4009~11 075粒,个体体长相对繁殖力为21.87~39.96粒/cm,个体体质量相对繁殖力为20.31~64.27粒/g。相关分析显示,个体绝对繁殖力与体长、体质量、空壳质量及卵巢质量之间均达到了极显著的相关水平,个体体长相对繁殖力与卵巢质量和肥满度之间为显著性相关,个体体质量相对繁殖力与体长、体质量、空壳质量之间呈显著性负相关,但与性腺指数和年龄呈正相关。     

长江中游贝氏(鳖)繁殖生物学研究

2016年4-12月在监利长江何王庙故道采集591尾样本,对长江中游贝氏(鳖)(Hemiculter bleekeri)性比、初次性成熟大小、繁殖季节、产卵类型、产卵群体组成及繁殖力等繁殖生物学指标进行了分析.结果显示:贝氏(鳖)总体雌雄性比1.44:1,与1:1存在极显著性差异;繁殖期间雌雄比2.5:1,非繁殖季节雌雄比为0.91:1.繁殖群体年龄结构为1-3龄,以1龄补充群体为主,属于第Ⅱ类型.初次性成熟体长:SL♀50=8.08 cm, SL♂50=8.47 cm,最小观测性成熟个体分别为:雌性7.5 cm,体重6.65 g, 1龄;雄性8.2 cm,体重8.13 g, 1龄.根据成熟系数变化和性腺发育期观察,推测其繁殖季节为4-6月,可能延至7月份.贝氏(鳖)绝对繁殖力为1703~9601粒/尾,平均为(5876.6 ± 1837.8) 粒/尾,与体重、性腺重均呈线性关系,与体长呈幂函数关系.相对繁殖力(FW)为204.7~406.5粒/g,平均(322.3 ± 49.7) 粒/g,与成熟系数呈幂函数相关;相对繁殖力(FL)为212.0~827.6粒/cm,平均(552.4 ± 136.1) 粒/cm,与体重幂函数相关.     

长江中游贝氏繁殖生物学研究

2016年4-12月在监利长江何王庙故道采集591尾样本,对长江中游贝氏(Hemiculter bleekeri)性比、初次性成熟大小、繁殖季节、产卵类型、产卵群体组成及繁殖力等繁殖生物学指标进行了分析。结果显示:贝氏总体雌雄性比1.44∶1,与1∶1存在极显著性差异;繁殖期间雌雄比2.5∶1,非繁殖季节雌雄比为0.91∶1。繁殖群体年龄结构为1-3龄,以1龄补充群体为主,属于第Ⅱ类型。初次性成熟体长:SL♀50=8.08 cm,SL♂50=8.47 cm,最小观测性成熟个体分别为:雌性7.5 cm,体重6.65 g,1龄;雄性8.2 cm,体重8.13 g,1龄。根据成熟系数变化和性腺发育期观察,推测其繁殖季节为4-6月,可能延至7月份。贝氏绝对繁殖力为1 703~9 601粒/尾,平均为(5 876.6±1 837.8)粒/尾,与体重、性腺重均呈线性关系,与体长呈幂函数关系。相对繁殖力(FW)为204.7~406.5粒/g,平均(322.3±49.7)粒/g,与成熟系数呈幂函数相关;相对繁殖力(FL)为212.0~827.6粒/cm,平均(552.4±136.1)粒/cm,与体重幂函数相关。     

新疆车尔臣河叶尔羌高原鳅繁殖策略

为探究叶尔羌高原鳅(Triplophysa yarkandensis)在车尔臣河的繁殖策略,基于2019—2021年在车尔臣河采集的544尾叶尔羌高原鳅样本,对其繁殖群体组成特征、繁殖期、初次性成熟大小、产卵类型、繁殖力等进行了研究和分析。结果显示,叶尔羌高原鳅的繁殖群体年龄范围为2～9龄,雌雄性比为1.16∶1,属于第二类型(P=K+D,K>D)。观测到的最小初次性成熟体长和年龄为:雌性111.0mm,2龄;雄性79.0mm,2龄;初次性成熟体长(SL50)和年龄(A50)为:雌性123.2mm,3.16龄,雄性90.9mm,2.95龄。根据不同性腺发育时期出现时间和比例、性腺成熟系数和卵径分布推测叶尔羌高原鳅为分批产卵类型,繁殖期为3—8月, 4—6月为繁殖盛期。绝对繁殖力平均为(61407±46143)粒,相对繁殖力平均为(743.87±321.78)粒/g。车尔臣河叶尔羌高原鳅群体相对于其他水域的叶尔羌高原鳅,拥有更大的平均体长、平均体重、初次性成熟体长、较高的绝对繁殖力和较低的相对繁殖力,这是车尔臣河叶尔羌高原鳅群体在食物稀少、生境恶劣且含沙量较大的环境中独特的繁殖策略...     

Gonadal sex differentiation and sex control in red sea bream, Pagrus major

The gonadal sex differentiation in red sea bream, Pagrus major, which is one of the most important species for aquaculture in Japan, was revealed histologically. The suitable conditions for induction of all-male groups in the fish were investigated, and functional males were induced by the conditions of oral administration of 17α-methyltestosterone. The sex determination of this fish was also discussed.     

Growth performance of mixed sex, hormonally sex reversed and progeny of YY male tilapia of the GIFT strain, Oreochromis niloticus

The growth performance of three experimental groups consisting of mixed sex fish (control), hormone-treated fish and progeny of YY male tilapia, all originated from the genetically improved farmed tilapia (GIFT) strain was evaluated. Masculinization of sexually undifferentiated fry was achieved by providing a supplement of 5 mg of 17-α-methyltestosterone per kg of feed over a period of 21 days (after sac absorption). Both mixed sex and progeny of YY male groups were fed a standard commercial ration. Mixed sex fish did not deviate significantly ( P >0.05) from the 1:1 male to female ratio. Percentages of male averaged 75% in hormone-treated fish and 95% in YY male group over the sampling periods and at final harvest. The effect of sex on weight and length was statistically significant ( P <0.001). The model used to analyse weight and length included experimental group and sex in each culture period as the fixed effects, and replicate cages as the random effect. Over the culture period of 141 days, there were no statistical differences ( P >0.05) in body weight and length between mixed sex, hormonally treated and progeny of YY males. There were also no significant differences in level of variability in harvest weight between three groups of fish when the data were classified into five categories (=<100, 100 to <150, 150 to <200, 200 to <250 and ≥250 g). It is concluded that monosex culture of all male tilapia would be of no advantage over mixed sex culture for the GIFT strain under conditions of cages suspended in earthen ponds.     

温度对杂合克隆牙鲆性别分化、性比和生长的影响

以有丝分裂雌核发育牙鲆(Paralichthys olivaceus)中的雄性和雌性作为父母本,进行人工授精获得杂合克隆牙鲆。从35日龄起,实验鱼类分别在16、19、22、25、28和31℃水温下培育至110日龄,观察其性别分化、性比和生长的差异。结果表明,性别分化与培育水温密切相关,在22、25和28℃水温下,60日龄开始性别分化;在16℃和19℃下,分别在70日龄和90日龄开始性别分化;而31℃下,110日龄仍未发生性别分化。通过180尾标本的组织切片观察,各温度下的杂合克隆牙鲆均为雌鱼,未发现雄鱼,表明高水温没有改变雌性性别。对于全长和体质量的生长,除31℃外,其他各实验组随着水温升高而生长加快;但是,55日龄后,25℃下的生长超过28℃,成为生长最快的温度。本实验结果证明杂合克隆牙鲆性别分化随水温升高而加快;性别比例不受温度影响,全部为雌性;25℃下牙鲆生长最快。     

Gonadal sex differentiation in protandrous anemone fish, Amphiprion clarkii

To clarify the process of sex differentiation in protandrous anemone fish, histological structure of their gonads was examined from 1 day to 214 days after hatching (dah). Gonadal development was first characterized by differentiation of ovarian tissues at 61 dah, followed by interspersed appearance of testicular tissues in the ovary at 214 dah.     

泥鳅雌雄性比对繁殖影响的试验

试验研究了不同雌雄比例对泥鳅产卵的影响。结果表明:7个组中产卵量随着雌性数目的增加而提高,但相对产卵量不同。在雄性为2条的情况下,相对产卵率随着雌性数目的增加相对产卵量逐渐降低。在雌性为2条的情况下,相对产卵量在2♀4♂组泥鳅的相对产卵量最高,为572.75颗/g。并不随着雄性的进一步增加而提高。这可能是由于雄性泥鳅在潜在竞争对手存在的情况下约束了自身的求偶行为,以避免精子的竞争。     

Morphology, endocrinology, and environmental modulation of gonadal sex differentiation in teleost fishes

Successful reproduction by an adult depends on the normal ontogenesis of the gonads, a complex process of cellular and histological differentiation that starts early in life. This process is theoretically predetermined by genetic factors and includes sensitisation of the bipotential gonads to endogenous endocrine factors prior to, during and even after commitment to maleness or femaleness. However, young fish are relatively vulnerable to a host of environmental (physical and chemical) factors that can affect this endogenous endocrine axis, disturbing or even overriding the putative developmental pathway. This sexually lability can be exploited to our advantage for the production of monosex fish populations of the most valuable sex for food production or aquarium fish trade. On the other hand, it represents also a potential path for undesirable influences from endocrine-disrupting chemicals and climatic factors, particularly environmental temperature. This paper provides a detailed account of the early histological process of gonadal sex differentiation, with special reference to gonochoristic species, and reviews the criteria employed to positively identify ovarian and testicular differentiation. It also reviews the development of endocrine competence and sensitivity of the differentiating gonads to exogenous influences in the context of the relative stability of genotypic sex determination in various fish species. Sex differentiation in some species seems to be under strong genetic control and may not require endogenous sex steroid production. Conversely, reliance on endogenous sex steroids for gonadal differentiation is observed in other species and this phenomenon is apparently associated with a higher incidence of environment (mainly temperature)-labile sex differentiation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular mechanisms of sex determination and gonadal sex differentiation in fish

We have used various genetic and molecular approaches to investigate the mechanisms of sex determination and gonadal sex differentiation in fish. DMY was identified as the sex-determining gene of medaka. In tilapia, endogenous estrogens act as natural inducers of ovarian differentiation, while DMRT1 may be important for testicular differentiation. The roles of these regulators in sex determination and gonadal sex differentiation were ascertained using a gene or hormonal blockade strategy.     

The role estrogens play in sex differentiation and sex changes of fish

Using genetically controlled all-female and all-male tilapia (Oreochromis niloticus), the role steroid hormones play in the sex differentiation was analyzed histologically, ultrastructurally, immunohistichemically and experimenntally. The results strongly suggest that endogenous estrogen acts as an ovarian inducer, and that the lack of steroid hormone including androgen is important for testicular differentiation. Moreover, the roles of steroid hormones in protogynous sex change of three-spotted wrasse (Halichoeres trimaculatus) and saddleback wrasse (Tharassoma duperrey) were examined. The results strongly support the hypothesis that the endogenous estrogen plays an important role in protogynous sex change.     

Gynogenesis induction and sex determination in the Eurasian perch,Perca fluviatilis

In the present study, we used meiotic gynogenesis, widely used in studies on sex determination, to confirm female homogamety in Eurasian perch, Perca fluviatilis. Sperm irradiated with UV for 400 s was used to artificially fertilized eggs. The diploid of the resulting embryos was restored by a heat shock (30 °C) applied to the eggs 5 min postfertilization, for 25 min. Fertilization (ranging between 45% and 75%) and survival rates at hatching (ranging between 3.4% and 46.6%) were not significantly different (P>0.05) between the diploid control and gynogenetics. The diploid controls and two batches of gynogenetics contained 100% diploid larvae, whereas two other batches of gynogenetics contained 6.7% and 10.0% triploid larvae. The sex ratios of the diploid controls were not significantly different from 1:1, whereas all gynogenetic families were 100% female. These results confirm female homogamety in Eurasian perch, demonstrated by the use of hormonally mascilinized breeders in a previous study.     

Induced sex reversal of dusky grouper, Epinephelus marginatus (Lowe)

The present paper describes sex reversal in dusky grouper, Epinephelus marginatus (Lowe). Over a 4-month feeding period, 5 mg kg^?1 of the male hormone 17-α methyltestosterone was combined with frozen fish as feed. After 2.5 months of treatment, the gonads of all six fish treated in the experiment presented tissues with oocytes and spermatogonia, and after 3 months, there were only a few remnants of oogonial tissue left in the gonads. All fish in the experiment gave sperm of varying quality after 4 months of the trial. The quantity of the hormone administered to the fish over these 4 months was 89-113 mg kg^?1. Spermatozoid motility varied from 95% to 40%, and lasted for about one hour in sea water. Using the combined sperm of three males, fertilization ranged from 50% to 95%. Fertilized eggs and hatched larvae continued to develop normally.