厚唇裂腹鱼性腺发育周期及血清中性激素含量变化

为探明厚唇裂腹鱼的精巢、卵巢周年发育及血清中性激素含量的变化，2020年8月—2021年8月，每月在克孜勒河采样，获得样本共计194尾，采用常规石蜡切片方法对其精巢和卵巢进行观察，以耳石为鉴定材料对厚唇裂腹鱼最小性成熟个体年龄进行研究，选取成熟鱼卵描绘卵径分布判断其产卵类型，采用酶联免疫法测定厚唇裂腹鱼各发育周期的雌二醇和睾酮的质量浓度。试验结果显示：厚唇裂腹鱼精巢和卵巢发育分为6个时期；雄鱼最小性成熟个体年龄为2龄，雌性最小性成熟个体年龄为3龄，精巢发育早于卵巢；厚唇裂腹鱼产卵期在3—5月，卵粒的数量百分比在直径2.9～<3.1 mm时出现峰值，产卵后的Ⅵ期卵巢中极少存在成熟的卵粒，判断其产卵类型为完全同步产卵类型；雌鱼与雄鱼血清中雌二醇和睾酮的质量浓度均在Ⅴ期时达到最高。厚唇裂腹鱼属于完全同步产卵类型，性腺于2017年3—5月发育成熟并产卵，雌二醇和睾酮的质量浓度在厚唇裂腹鱼繁殖期间显著增加。     

人工养殖下施氏鲟Acipenser schrenckii、达氏鳇Huso dauricus及其杂交后代的繁殖特性

2013年11月~2014年11月,测量5批次施氏鲟Acipenser schrenckii、黑龙江杂交鲟(达氏鳇Huso dauricus♀×施氏鲟♂)和达氏鳇Huso dauricus(共644尾)的体长、体质量,观察其生长、个体繁殖力、卵巢发育、卵径、卵质量和卵色等。结果表明:3种鲟雌亲鱼的体长与体质量差异显著,施氏鲟的体长和体质量显著小于杂交鲟与达氏鳇(P0.05),而杂交鲟的体长和体质量则显著小于达氏鳇(P0.05)。施氏鲟、杂交鲟和达氏鳇雌亲鱼的成熟系数(GSI)和繁殖力差异显著,杂交鲟的GSI和平均绝对繁殖力显著高于施氏鲟和达氏鳇(P0.05),而施氏鲟与达氏鳇的GSI无显著性差异(P0.05)。杂交鲟的相对繁殖力(Fw)显著高于施氏鲟与达氏鳇。3种鲟雌亲鱼产卵质量与体质量比值以10%~15%为主,该比值范围内雌性施氏鲟个体数约占同龄雌性个体的42.66%,杂交鲟为42.91%,达氏鳇为41.93%。施氏鲟和杂交鲟的卵多为棕色,而达氏鳇的卵为棕灰色。达氏鳇的卵径显著大于施氏鲟与杂交鲟。杂交鲟的绝对繁殖力、相对繁殖力及成熟系数均高于施氏鲟与达氏鳇,具有明显的杂交优势。     

养殖银鲳第一次性周期性腺发育组织学

采用常规石蜡切片技术对人工养殖银鲳的性腺发育情况进行了研究。结果表明,在1～2月龄,养殖银鲳精巢处于第Ⅰ期;3～4月龄发育至第Ⅱ期;5月龄时发育至第Ⅲ期;6月龄时发育到第Ⅳ期;在7月龄时即能达到性成熟;在越冬的8～10月龄退化至第Ⅲ期,之后又开始重新发育,并在11～12月龄达到成熟。卵巢在3～4月龄时发育至第Ⅰ期;5月份发育至第Ⅱ期;6月龄发育到第Ⅲ期;7～8月龄的越冬时期卵巢退至第Ⅱ期;越冬之后的9～10月龄时卵巢继续发育,并在11～12月龄时达到性成熟。银鲳精巢和卵巢发育都为不完全同步型,且精巢发育较卵巢快。本研究为银鲳性腺发育及人工繁育研究提供了基础资料。     

范厝库区鲂性腺发育周年变化的观测

范厝库区鲂雌性成熟年龄为3龄，雄鱼2龄；性成熟后，鲂性腺发育具有明显周年变化规律，卵巢精巢可分为六个发育时期：冬季，达性成熟的鲂卵巢为Ⅲ期，精巢为Ⅳ期；每年5月份雌鱼成熟系数提高，是该库鲂鱼的主要产卵期；3～5龄鲂绝对生殖力均值为157000粒，相对生殖力均值为218粒。     

养殖银鲳性腺发育规律和性类固醇激素变化

为掌握养殖银鲳的性腺发育规律及其与性类固醇激素水平的关系,本研究采用组织切片技术和酶联免疫吸附法(Elisa),观察养殖条件下银鲳的精巢与卵巢发育特征和血清中性类固醇激素的周年变化,并分析性腺成熟指数(GSI)、肝重指数(HSI)和肥满度(CF)与性腺发育的关系。结果显示,养殖银鲳雌鱼1龄即可发育成熟,成熟卵巢呈一对""形的囊状结构。11月份有近一半个体发育至III期,33.3%已发育至IV期,12月—翌年1月越冬期间约2/3退化至II期,3月又迅速发育至IV期,4月份达到V期并产卵,5月份产卵结束卵巢进入恢复期IV期。银鲳精巢属小叶型,III期精巢出现小叶腔,IV期精巢出现精子,精巢发育速率快于卵巢,即"雄性早熟",7月龄约20%个体可达到性成熟,越冬时退化至III期,3月重新发育,精子分批成熟排精。雌鱼GSI值为0.19%~12.89%,HSI为0.97%~2.30%,CF为2.30~3.08 g/cm~3,雄鱼的GSI为0.08%~2.62%,HSI值为0.73%~1.83%,CF为2.11~2.80 g/cm~3,GSI值在V期时达到最大,HSI和CF值则于IV期达到峰值。雌鱼血清中雌二醇(E2)周年表达水平为23.27~59.13 pg/m L,雄鱼为15.90~36.20 pg/m L,雌鱼的睾酮(T)为14.57~68.67 nmol/L,雄鱼的T为18.62~66.49 nmol/L,E2水平与HSI值呈现显著正相关关系,T表达水平与GSI值呈现显著正相关关系。研究表明,银鲳血清中性类固醇激素含量与精巢和卵巢的发育密切相关,可作为了解养殖银鲳性腺发育的重要指标。     

翎电鳗卵巢发育组织学研究

翎电鳗是深受广大水族爱好者喜爱的观赏鱼类,研究其卵巢发育规律,可以为该鱼的人工繁育提供理论基础。翎电鳗成熟卵巢为囊状,泄殖孔位于体前端下颌后方。常规石蜡切片方法对其卵巢进行观察发现,翎电鳗的卵巢发育分为6个时期,卵子发育分为5个时相。4月龄雌鱼卵巢中有较多第Ⅱ时相卵母细胞,少量卵原细胞,发育至第Ⅱ期;8月龄雌鱼卵巢中含有卵原细胞、第Ⅱ时相和第Ⅲ时相卵母细胞,发育至第Ⅲ期;10月龄雌鱼卵巢中同时存在卵原细胞、第Ⅱ时相、第Ⅲ时相和第Ⅳ时相卵母细胞,发育至第Ⅳ期,达性成熟;11月龄雌鱼卵巢中第Ⅴ时相卵母细胞占主要成分,为Ⅴ期。Ⅴ期卵巢中成熟卵径的大小分布在1.08～1.15 mm和1.78～1.84 mm。翎电鳗雌性亲鱼在理想环境下存在短时间内一批卵排出后新一批次的卵成熟并被释放的可能,产卵类型属分批同步型。     

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.     

青海湖裸鲤繁殖生物学研究

通过常规生物学测定、组织切片等手段,较详细的研究了青海湖裸鲤的繁殖生物学。卵母细胞从第3时相发育到第4时相基本同步,产后卵巢和精巢的组织学结构恢复到Ⅱ期。青海湖裸鲤为重复产卵类型,以Ⅳ期卵巢越冬,其卵巢1年只成熟1次,已达性成熟的个体并不是每年都进行繁殖活动。青海湖裸鲤性成熟迟、繁殖力低。每年5～7月,裸鲤洄游到沿湖各河流中繁殖,沙柳河、布哈河和黑马河3条河流为其主要产卵场。调查的繁殖群体总的性比(♂：♀)为1．66：1。总繁殖群体中,雄性个体最小体长130．0mm,体重28．0g,年龄4龄;雌性个体最小体长170．0mm,体重51．0g,年龄5龄。青海湖裸鲤性成熟群体的性体指标1年只有1个峰值,出现在繁殖盛期的6～7月。其平均成熟卵径为2．33mm,平均绝对繁殖力为4337．81粒,平均相对繁殖力为27．09粒／g。     

人工繁养湘华鲮性腺发育的组织学研究

2011—2017年在室外土池塘繁殖饲养湘华鲮Sinilabeo decorus tungting,2018年3月、4月和5月采集湘华鲮子一代样本共计154尾,采用常规生物学测量和组织学方法,观察湘华鲮性腺的形态结构与特征。观察表明:湘华鲮子一代卵巢和精巢发育均分为6期,雌鱼最小性成熟年龄为5+,雄鱼最小性成熟年龄为4+。5龄以上湘华鲮卵巢在3—5月从Ⅲ期发育至Ⅳ期,在5月中下旬经过催产可发育为Ⅴ期,在一个性周期内产卵一次,为同步产卵型。4龄以上的湘华鲮精巢在3月处于Ⅲ～Ⅳ期,4月下旬—5月初发育到Ⅳ～Ⅴ期。池塘养殖条件下,湘华鲮可达到性成熟,进行全人工繁殖。本研究为湘华鲮的全人工繁殖提供了理论依据。     

水泥池养殖香鱼性腺发育的观察

对水泥池养殖的香鱼卵巢、精巢发育做组织学观察,并与洄游型、陆封型香鱼的性腺发育做比较:养殖香鱼卵母细胞的结构和洄游型香鱼、陆封型香鱼基本一致;受精孔和精孔细胞出现的时间早于洄游型香鱼和陆封型香鱼。养殖香鱼卵巢发育略早于野生香鱼,但发育速度比野生香鱼慢,尤其慢于陆封香鱼。精巢结构属叶型壶腹型结构。雄鱼发育成熟早于雌鱼,能自然排精。雌鱼不用激素诱导即可获得游离卵。     

龙溪河张氏■生长与繁殖初步研究

基于2011年7-12月和2012年3-6月采集的样本,对长江上游支流龙溪河张氏■(Hemiculter tchangi)种群生长和繁殖特征进行研究。研究共采集张氏■样本227尾,采用鳞片鉴定年龄,测量鳞片半径,进行体长退算,选取成熟鱼卵描绘卵径分布,估算繁殖力,研究其年龄结构、生长特征和繁殖习性。结果显示:龙溪河张氏■体长101~187 mm,平均体长为(141±15) mm,体重12.5~82.8 g,平均体重为(39.3±13.2) g。群体雌雄性比为1.38∶1。群体年龄组成为1~5龄,其中3龄最多,占总样本的48.5%。群体体长与鳞径呈线性关系,雌雄无显著差异,其关系表达式为L=32.08 R+43.08;体长与体重的关系呈幂函数关系,其关系表达式为W=10-5×0.13.035。张氏■种群生长式型属于等速生长,生长方程表达式为:Lt=242.69[1-e-0.164(t+2.71)];Wt=170.66[1-e-0.164(t+2.71)]3.035。种群繁殖时间为4-8月,雌雄群体1龄达性成熟,其中雌性生物学最小型体长为110 mm,体重为28.7 g;雄性生物学最小型体长为105 mm,体重为14.6 g。龙溪河张氏■种群卵径为单峰型,平均卵径为(0.72±0.05) mm;种群绝对繁殖力平均为(32 688±11 426)粒;体长相对繁殖力FL平均值为(219±76)粒/mm;体重相对繁殖力FW平均值为(680±215)粒/g。     

杂交鲟(施氏鲟♀×西伯利亚鲟♂)早期生长研究

将体质量(0.014±0.001) g的杂交鲟(施氏鲟♀×西伯利亚鲟♂)以流水方式养殖87 d,饲养期间随时观察鱼的体征变化,自第7 d开始,每10 d取样测体质量和全长。试验结果显示,水温7~14℃时,初孵仔鱼躯体纤细透明,头部小且紧挨卵黄囊,卵黄囊椭圆形,约占整个身体的2/3。仔鱼发育至第7 d时始开口摄食,进入混合营养阶段,发育至第9 d时卵黄囊基本消失,仔鱼完全进入外源营养阶段,第37 d时,仔鱼发育已进入稚鱼期,发育至第57 d时器官发育基本完善,外部形态和体色近成鱼,进入幼鱼期。仔稚鱼全长日均增长量为1.67 mm,平均瞬时增长率为2.26%,全长(L)与日龄(t)生长关系式为L=0.1546t+1.2357(r2=0.9812)。体质量日均增长量为0.25 g,平均瞬时生长率为5.51%,体质量(m)与日龄生长关系式为m=0.3379e0.0479t(r2=0.9851)。体质量与全长生长关系式为m=0.0289L2.3444(r2=0.993),幂指数小于3,表明杂交鲟仔稚鱼的体质量生长比全长生长慢,为异速生长。     

中华鲟血清卵黄蛋白原水平的初步观察

通过碱不稳定性蛋白结合磷法测定不同年龄中华鲟(Acipenser sinensis)血清中磷含量,以磷的含量变化反映卵黄蛋白原(VTG)变化情况。实验鱼为人工养殖0.5、1、2、3、4、5、6、8、9、10龄中华鲟和野生成熟中华鲟,共81尾,其中8尾野生雌鱼在人工繁殖前后各取样2~4次,共测97个血液样本。结果显示:低龄中华鲟VTG含量较低,最低值在5龄,含磷量为(4.6±1.6)mg/L,5龄后增加,成熟后达到最大,含磷量为(52.0±4.5)mg/L。在性腺不同发育时期,雌性个体在Ⅱ~Ⅴ期VTG的含量增加,Ⅱ~Ⅲ期增加速度较快,随后变缓,Ⅴ期达到最高水平,Ⅵ期降低;而雄性个体在Ⅱ~Ⅳ期VTG的增加量很少,Ⅳ期达到最高水平,含磷量为(28.7±12.2)mg/L。繁殖雌鱼产前VTG含量最高,含磷量为(62.5±8.7)mg/L,产后低于产前。此外,发现产后鲟鱼卵巢液中含量低于其血清中含量,但高于其他年龄组血清中的水平。本实验表明淡水养殖的中华鲟有可能达到性成熟。     

养殖中华鲟性腺发生与分化的组织学研究

用组织切片方法研究人工繁育中华鲟的性腺发生及两性分化过程。中华鲟出膜后3d，原始生殖细胞以单细胞的形式存在于肾管区腹下方。出膜后11d，生殖褶形成，到2月龄和7月龄时，性腺中分别出现血管和脂肪组织，直到8月龄性腺均处于两性未分化状态，划分为0期。9月龄(体重0．6～1．1kg)，性腺出现组织学水平上的两性分化，性腺划入I期。I期性腺中，精(卵)原细胞进行有丝分裂。以初级精(卵)母细胞出现作为Ⅱ期开始的标志，精巢和卵巢分别于1．8～2．2年龄(1.55～5．6kg)和2．5～3．0年龄(3．1～8．2kg)进入Ⅱ期。3年龄以后，性腺发育分化陆续达到肉眼可分辨性别的程度，5～5．6年龄(18～35．5kg)时，所有的性腺能肉眼区分雌雄，但精巢和卵巢仍都处于Ⅱ期，其中卵母细胞的卵径为60～240μm。     

中华鲟子一代配子质量及其子二代生长特征分析

通过测定卵的直径、卵粒质量、受精率和孵化率系列指标以及精子的激活率、快速运动时间和寿命系列指标对人工驯养子一代中华鲟配子进行质量评价,并通过该批受精卵孵出的子二代系列生长指标进行其发育状况分析。结果显示,子一代所产卵子形态饱满,卵径平均3.71 mm,小于自然繁殖群体。与历年在本基地养殖的自然繁殖群体统计资料相比,其受精率(60.1%)和孵化率(36.8%)处在中等偏下的水平。2012年和2013年的精子活力监测结果发现,子一代精子有效运动时间(漩涡运动+快速运动)均较野生群体高。表明子一代卵子质量较野生群体有所降低,而精子活力则较野生群体高。与历年该基地集约化养殖系统培育出的子一代中华鲟相比,子二代的生长表现出显著的阶段差异性,其中仔鱼阶段生长较慢,稚鱼和幼鱼阶段生长优势则较明显。研究表明,促进人工驯养条件下的子一代后备亲鱼性腺发育完善,以获得较高质量的配子和子二代,对防止中华鲟种质退化至关重要。     

Sex-Linked Growth Divergence of Summer Flounder from a Commercial Farm

ABSTRACT

In the wild, it is known that adult female summer flounder, Paralichthys dentatus, grow at a faster rate and to a larger body size than males. The age or size at which this divergence in growth rate occurs is not known. At GreatBay Aquafarms, Inc., the sex ratios of three production lots of juvenile fish was examined to determine if females grow faster than males under commercial cultivation and to identify the age and/or size at which sex-linked growth divergence begins. Production lots 99-2, 99-1, and 98-3, ages 8, 12, and 15 months (post-hatch), respectively, were sampled. The gonadal tissue from fish smaller than 60 mm was examined by histology. Fish larger than 12 cm were dissected, and gross observation was used to determine sex. With the exception of two samples that appeared to be males, gonadal tissue from fish under 60 mm appeared undifferentiated. In production 99-2 (8 months) no significant association between the percentage of female fish and body size was found. However, in productions 99-1 (12 months) and 98-3 (15 months) percentage of female fish increased significantly with body size group. At the time of sampling, the average weight of females from lots 99-2, 99-1, and 98-3 was 1.05, 1.1, and 1.4 times heavier, respectively, than males. Results from this study suggest that sex differentiation in summer flounder occurs at 6 to 12 cm, and indicates clear value of all-female production for the commercial cultivation of summer flounder.     

Preliminary Evidence of Sturgeon Density and Other Stressors on Manifestation of White Sturgeon Iridovirus Disease

Two studies were conducted using 5- to 6-month-old juvenile (mean weight: 3-4 g) white sturgeon, Acipenser transmontanus, to examine the effects of density and other stressors on manifestation of disease caused by the white sturgeon iridovirus (WSIV). In the first study, replicate groups of Snake River white sturgeon were stocked at three densities (953, 1,907, and 3,178 fish/m³) in 0.31-m³ fiberglass aquaria with spring water flow through of 30.0 L/minute. No significant (P > 0.05) differences were observed among the three groups during the initial 6-week period. However, the high density group cumulative mortality was significantly (P < 0.05) greater than the mortality detected in the other groups at 59 days. Pathognomonic signs of WSIV were detected in moribund fish from each group by histological evaluation; however, no virus was isolated. These results suggested that maintaining low sturgeon densities in fish younger than I year may be a prudent strategy for minimizing mortality caused by WSIV. In the second study, triplicate or replicate groups of Kootenai River white sturgeon that had been transported for approximately 14 hours at 2-6°C, prior to acclimation at lS°C, were stocked at high and low densities previously tested. No signs of WSIV or abnormal mortality were observed during the initial 2-week period. However, after 36 days the mortality increased to 10-18% and 14-18% in the low and high density groups, respectively, and signs of WSIV disease were detected in moribund fish examined from each treatment by histological evaluation. The presence of the virus was further confirmed by electron microscopy of gill tissue. Although fish density did not appear to affect the occurrence of disease or cumulative mortality, the results suggested that a stressor (e.g., handling, transport, and temperature) in subyearling sturgeon may enhance clinical manifestation of WSIV.     

洪泽湖河蚬种群生长方程的估算及其应用

015年4月（春季）、8月（夏季）、11月（秋季）和2016年2月（冬季），对洪泽湖河蚬（Corbicula fluminea）进行了采样调查，共设置30个样点，从各采样点分别随机选取30个河蚬，记录不同壳长、壳宽、壳高和体重的河蚬数量，计算其年龄组成和分布频率，并统计不同壳长组的年龄分布情况，以期为其资源的合理利用与保护提供参考依据。结果显示，形态指标和体重呈现显著的季节变化；壳长、壳宽、壳高、体重和年龄范围分别为1.47~40.82 mm、3.93~27.81 mm、8.46~37.40 mm、0.43~20.56 g和1~5龄，壳长、壳宽、壳高、体重和年龄的优势组分别为15~35 mm（92.6%）、12~20 mm（83.2%）、15~31 mm（88.8%）、2~10 g（79.6%）和2~3龄（76.5%）；其相对增长率和生长指标随年龄的增加逐渐降低；壳长-体重关系式为W = 1.5×10-3L 2.5795(R2= 0.90)，Von Bertalanffy壳长和体重生长方程分别为Lt= 39.42 ×[1 - e- 0.33 (t + 0.6)]和Wt= 22.574 × [1-e- 0.33 (t + 0.6)]3；拐点年龄为2.73龄，对应的体重和壳长分别为6.69 g和26.28 mm。分析表明，洪泽湖有适宜河蚬生长的环境条件，且秋季为最佳捕捞季节；年龄与壳长和体重显著正相关，可以通过河蚬的体长和体重来估测其年龄；其生长可分为3个阶段，1~2龄为快速生长期，2~3龄为稳定期，3~5龄为衰老期。建议将拐点年龄所对应的壳长26.28 mm作为洪泽湖河蚬开捕壳长。     

Use of endoscopy for gender and ovarian stage determinations in Russian sturgeon (Acipenser gueldenstaedtii) grown in aquaculture

The Russian sturgeon (Acipenser gueldenstaedtii) is native to the Caspian Sea, the Black Sea and the Azov Sea. It used to breed in the main incoming rivers, until dam construction in the mid 20th century blocked upriver spawning migration. Aquaculture of Russian sturgeon has only recently begun, prompted by their declining populations in natural habitats and the rise in meat and caviar prices. However, information on their gonadal development and puberty under culture conditions is incomplete.

Because sturgeons have no external sexual dimorphism and there are no external markers for sexing, internal examination of the gonads must be employed for gender identification as well as to monitor their development. The present study describes endoscopic and histological observations of the gonads of young Russian sturgeons aimed at identifying gender and monitoring ovarian developmental stage in females up to the age of 6 years, when they enter their first puberty cycle, as well as at 7 years of age, when they have completed vitellogenesis, under culture conditions. This information, as related to fish age and size, is of vital importance to commercial farming of Russian sturgeon for caviar production and reproduction.

For gonadal observations in both sexes, we used an endoscopic system consisting of a 4 mm, 14 cm long cystoscope sheath incorporated with fiber-optic light transmission, connected to a halogen cold light source and a miniature videocamera with a control unit attached to a color monitor. This system allowed us viewing of the fish's abdominal organs, and to save pictures of selected areas of the gonads on a computer as the fish's personal record. Ovarian biopsies were taken in parallel for histology at typical stages of gonadal development.

Gender could be identified with this system as early as at 3 years of age and the sex ratio under culture conditions of females, males and unidentified gender were 55, 40 and 5%, respectively.

Not only did large differences occur in the developmental stages of female of the same age group, but also ovarian development was highly asynchronous at the early vitellogenic stages. In late vitellogenesis, at the “gray egg” stage (1600–2600 μm diameter), the oocytes were quite regular in size and color, and remained so until the final stages of maturity.

Our study suggests that endoscopy is an efficient method for both gender identification at an early age, and for determination of gonadal development stage in sturgeon aquaculture. The ability to see the whole intact gonads of anesthetized fish can reveal important management and research information, with minimal damage or stress to the fish.