不同温度下大西洋鳕（Gadus morhua）个体发生早期胚胎生长和卵黄蛋白的利用

本文报道了自受精至孵化,不同培育温度（０－６．１℃）大西洋鳕胚胎生长和卵黄及卵蛋白吸收动态。     

革胡子鲶实用养殖技术（三）

革胡子鲶实用养殖技术（三）三、苗种的培育与运输鱼苗孵出后两天，卵黄囊基本被吸收完毕，便开始摄食。开始以轮虫、小水蚤等浮游动物为食，以后便可吃大型浮游动物及人工饲料。革胡子鲶游动迟缓，易被水蛇、蝌蚪、水蜈蚣、松藻虫等敌害危害。因此，在苗种培育中要严格按...     

卵形鲳鲹的早期胚胎发育

对人工繁殖的卵形鲳鳆（Trachinotus ovatus）受精卵的胚胎发育过程进行了连续观察。受精卵由人工养殖的性成熟亲鱼，经人工催产、自然产卵受精获得。卵形鲳鲮的成熟卵呈圆形，平均卵径为967．8μm。受精卵在水温18～21℃、盐度31的条件下，胚胎发育历时41h27min后孵出仔鱼。胚胎发育为盘状卵裂，胚体后期的发育速度较快；仔鱼脱膜孵化的速度非常快，基本上在1min内就可以完成。初孵仔鱼平均全长为1．548mm，卵黄囊较大。     

施氏鲟全人工繁殖研究初报

自7－8龄后备施氏鲟（Acipenser schrencki)亲鱼群体中选出成熟较好的亲鱼进行人工催熟培育,其中1尾雌鲟,5尾雄鲟效果较好,经催产,手术取卵,干法授精和孵化,获受精卵19095粒,孵出健康鲟苗8714尾,受精率30．12％,孵化率45．63％,受试鲟术后20d左右开始摄食,伤口完全愈合,孵出的鱼苗经9d暂养,卵黄吸收完毕,开始摄食,发育正常。     

庭院牛蛙养殖技术（下）

３．饲养管理（１）投饲蛾蚪孵出３～６天后，卵黄囊吸收完毕，此时开始吃食，须投喂人工饲料，如蛋黄汁、豆浆等，均匀泼洒投喂；７～３０天时，蝌蚪由１．７ｃｍ增长至４．２ｃｍ，并长出尾芽，可投喂螺肉、鱼肉、鱼肠和动物内脏（未腐烂变质）、玉米粉、米糠、麸皮、豆饼等，每１０００只蝌蚪日投饲量４０～７０ｇ（动物性饲料占６０％，植物性饲料４０％）；３０天后到变态，每１００只蝌蚪日投饲量４０～８０ｇ（动物性饲料占４０％，植物性饲料６０％）。糠、麸皮等粉状饲料煮熟搓成团投喂，鱼肠、动物内脏等动物性饲料切碎投喂较好。…     

山女鳟人工繁育技术试验

本研究系统介绍了山女鳟人工繁育的主要技术要点，从山女鳟的亲鱼选择及培育、人工采卵、人工孵化等方面进行了系统介绍。本次研究内容主要来自黑龙江水产研究所渤海冷水性鱼类试验站的山女鳟人工繁育的主要过程及一些相关资料。池养山女鳟2年性成熟，产卵排精后死亡率很高，寿命2—3年，多为2年，及少可达4年。山女鳟繁殖时间是10月至11月份，繁殖水温在13℃以下，水温15℃左右开始产卵，怀卵量与鱼体大小成正比例，多在300粒左右，卵重占鱼体重的23—24％。满2年的山女鳟大的可达500g左右。416g重亲鱼，可采卵1360粒，760g重的亲鱼，可采卵2799粒。卵为端黄卵，球形，沉性。直径3．5—6．0mm。卵黄淡黄色或橙黄色，受精卵孵化积温达200℃进入发眼期，积温400℃破膜孵出。人工养殖条件下山女鳟1周年生长最高可达130g，平均值为56g。采用挤腹采卵，取精，干导法人工授精，待受精止水膨胀后放入桶式孵化器进行流水孵化。     

丁Gui胚胎发育和卵黄囊仔鱼摄食研究

对丁Gui的胚胎发育进行了连续观察，并对其卵黄囊仔鱼在开口摄食之前的发育、生长以及不可逆点作了实验研究。结果表明：（1）丁Gui受精卵在水温21.5℃时，胚胎发育时间约为52h；（2）仔鱼在孵出后第7天开始摄食，初次摄食率第9天达100%，第12天降到50%，进入不可逆点；（3）仔鱼对卵黄囊的日净消耗量的最大值出现在出膜后第1天，体长最大增长率出现的在出膜后的第2天；（4）仔全出膜后第8天，卵黄囊全部吸收，同时，饥饿期仔鱼开始出现负生长。     

尖塘鳢的全人工繁殖及其胚胎发育

对尖塘鳢进行了全人工繁殖的研究和胚胎发育观察。尖塘鳢鱼苗经养殖和强化培育至1^＋龄可达性成熟。经生态控制或人工催产可使其产卵,产卵率为65．6％～100％,受精率为85．1％～90．3％。尖塘鳢受精卵透明无色,整个卵子成茄子状或长梨形,长径1．3～2．4mm,短径0．56～0．7mm,卵黄囊中央有几十个脂肪球。受精卵细端具有由粘着丝组成的附着盘,盘宽0．15～0．17min,粘着丝长0．20～0．23mm,尖塘鳢卵子为端黄卵,在水温26．8～30oC时,受精后32min,出现第1次卵裂,受精后30h 25min仔鱼孵出,孵化率为76％～85．6％。刚孵出仔鱼全长2．9～3．11nm。卵黄囊颇大,长径0．8～1．1mm,短径0．35～0．6mm。4日龄仔鱼全长．3．5～3．9mm,肌节数7～10＋14～17,可以平游,心跳为每分钟120～150次,卵黄基本吸收完,口能自主张合,可投喂人工饵料。     

泥鳅胚胎和幼鱼发育的研究

本文研究了用人工授精、孵化方法获得的泥鳅胚胎、幼鱼的形态特征。此项研究于1983年3—5月份在珠海市进行。卵圆球形，具弱粘性，卵径0．72-0．84毫米。在水温19．5—23℃情况下，多数受精卵经26小时40分后孵化出苗。初孵仔鱼全长1．95—2．4毫米，体节26-32对。在水温19—28℃情况下，孵化2天后，幼鱼具长条状外鳃。5天后，幼鱼卵黄囊大部分被吸收。15天后，外鳃消失，内鳃形成。45天后，幼鱼外部形态发育完全，形似成体。     

大菱鲆受精过程的细胞学观察

采用人工授精和组织切片技术对大菱鲆（Scophthalmus maximus L．）受精过程进行细胞学观察。大菱鲆成熟卵处于第二次成熟分裂的中期。精子入卵后，卵子被激动，第二次成熟分裂继续进行，同时发生皮层反应；受精后15min出现精子星光；受精后20min雄原核早于雌原核形成，然后两性原核逐渐靠拢；受精后30min两原核相互靠拢，结合线清晰；受精后40min两原核结合线逐渐消失联合成合子核，之后合子核核膜消失；受精后50min合子核处于第一次有丝分裂中期；受精后60min第一次卵裂完成。[中国水产科学，2006，13（4）：555—560]     

Hatching time effect on the intra‐spawning larval morphology and growth in Northern pike (Esox luciusL.)

Based on the analysis of 11 morphometric variables of body (total length, body area and perimeter, myotome height and eye diameter) and yolk sac (length, height, area, perimeter and volume) of pike larvae, the aim of this study was to evaluate how larval size at hatching and growth of larvae hatched from single egg batches vary according to three hatching times: early, mid and late. Hatching time structures strongly pike larval morphometrics. Early hatched larvae have smaller body sizes at hatch, faster growth and higher yolk use efficiency than late hatched ones. Early hatched larvae seem to be premature and hatch at precocious developmental stage whereas late hatched individuals continue their growth within the egg shell and hatch at larger size but with lower reserves (yolk). A compensatory growth phase was observed for the early hatching pike larvae particularly during the first 5 days post hatch. Consequently, no significant difference in body parameters was recorded from day 10 post hatching whatever the hatching time. The higher growth accomplished by early hatched larvae may be related to a particular metabolic activity that converts more efficiently yolk into body tissues.     

Tolerance of lake trout, Salvelinus namaycush (Walbaum), sac fry to dissolved gas supersaturation

Abstract. The tolerance of sac fry of lake trout, Salvelinus namaycush (Walbaum), to the acute effects of gas supersaturation, from hatching to swim-up, was tested using six gas levels, ranging from ΔP 8 to 148. Although many fish were moribund by the time the yolk was nearly absorbed, mortality during the 40-day study was negligible; survival to swim-up was 96–99%, including 99% survival at ΔP 148. Of fish examined at ΔP 42, 40% showed bubble formation around the rim of the eye. Signs of trauma were greatest at ΔP 119 and 148, and included intestinal bubbles, a distended abdomen, and bubbles around the eye, in the mouth and in jaw tissues.     

Embryonic expression of UCP2 in rainbow trout (Oncorhynchus mykiss)

Uncoupling proteins are mitochondrial anions transporters that dissociate respiration from ATP synthesis through proton leaks. Uncoupling protein 2 reportedly plays a role in several physiological processes such as energy partitioning, nutrition, and fatty acid metabolism. The mRNA expression of rainbow trout UCP2 genes (UCP2A and UCP2B) was monitored during embryogenesis and early larval development. Both genes were recruited early and displayed similar steadily decreasing patterns from fertilization until hatching. The expression of UCP2A and UCP2B appeared significantly differentiated after hatching and during the yolk sac absorption, with UCP2A displaying higher expression. We suggest that UCP2 expression profiles in the rainbow trout embryo could be associated with the utilization of lipids as a source of energy during development.     

Larval development in European hake (Merluccius merluccius L.) reared in a semi-intensive culture system

Eggs of European hake (Merluccius merluccius L.) were stripped from fish caught at sea. Larvae were kept under semi‐intensive conditions at around 12°C. In addition, eggs were incubated in single wells at 9.2, 12.7 and 14.5°C, where hatching, development and survival were closely examined. During the larval stage, a total of 299 larvae were sampled to follow development and growth. In addition a small number of juveniles were sampled. Larvae hatched approximately 4 days after fertilization, and were 2.9 mm in total length (TL). At 6‐day post hatching (dph), the larvae were 4.1 mm (TL), the jaw apparatus was developed, and the larvae had started to feed. Most of the growth during the early larval period is restricted to the head, and there is almost no increase in length for the first 3–4 weeks post hatching. Teeth and pelvic fins appear at 25 dph. Development of unpaired fins at approximately 30 dph marks the start of the larval–juvenile transition. Weaning to formulated feed was accomplished 50 dph, when external morphology was similar to that of adult hake.     

Is batch variability in hatching time related to size heterogeneity and cannibalism in pikeperch (Sander lucioperca)?

Larval size heterogeneity is known to induce cannibalism, and procedures to avoid larval size differences are consequently implemented already during egg incubation and hatching. We investigated the relation between larval development variability, size heterogeneity and cannibalism in pikeperch. Larvae were sorted into five groups according to the time of hatching during a 65‐h period. The larvae with different times of hatch were then reared separately or together during an 18‐day period. Late hatched larvae were longer (P=0.003) and had less yolk remaining (P<0.001) than early hatched individuals at the time of hatching. However, on 11 days post fertilization, the late‐hatching larvae tended to have larger yolk reserves than earlier hatched individuals (P=0.07). Furthermore, the next day, a lower proportion in the late fraction had switched to exogenous feeding (P=0.024). That larvae with a late hatching time developed slower suggests a positive relationship between the hatching time and the embryonic developmental rate. However, differences in the length and available yolk reserves at hatching between larval fractions with different hatching times suggest that hatching is not strictly associated with a specific developmental stage, and that factors other than the development rate of the embryo are involved in the timing of hatching.     

Mesocosm: A Reliable Technology for Larval Rearing of Diplodus puntazzo and Diplodus sargus sargus

Species diversification is today considered as a major issue for the sustainable development of the Mediterranean aquaculture. For successful propagation of any species however, larval rearing is considered a bottleneck and therefore the development of appropriate tools is essential. Mesocosm is a semi-intensive technology that facilitates larval rearing of several species integrating principles of both intensive and extensive aquaculture, which solves biological problems and many of their technical, human and economical consequences. The extensive (and now even the semi-extensive) strategy is used in the most critical segments of the rearing process during the early developmental stages, when larvae are still extremely weak, sensitive to intensive environment, easily stressed and difficult to feed. The intensive strategy is used as soon as larvae are considered mature enough to be reared easily using classical methods. The technology was used for the rearing of two species, with potential for aquaculture, the sharpsnout seabream (Diplodus puntazzo) and the white seabream (Diplodus sargus sargus). Three groups of each species were monitored for a period of 50–70 days post hatching. Survival for both species was about 54% at the end of the trials. Sharpsnout seabream larvae reached 19.6 ± 0.9 mm total length and 107.2 ± 31.9 mg body weight 50 days post hatching. White seabream larvae 60 days post hatching reached 32.7 ± 2.7 mm total length and 450 ± 70 mg body weight. In order to verify the economical viability of the technology, the individual production cost for each species was estimated and reached ¢0.027 for white seabream and ¢0.043 for sharpsnout seabream. Results indicate the reliability of the technology for the larval rearing of the two species.     

Comparison of dietary phospholipids and neutral lipids: effects on gut, liver and pancreas histology in Atlantic cod (Gadus morha L.) larvae

The aim of the present study was to compare effects of dietary n-3 highly unsaturated fatty acids (HUFA) being incorporated in the phospholipid (PL) or in the neutral lipid (NL) fraction of the larval feed, on larval growth and histology of digestive organs in Atlantic cod ( Gadus morhua L.) larvae. Three isoproteic and isolipidic diets, labelled according to the percentage of n-3 docosahexaenoic acid and eicosapentaenoic acid contained in NL1 or in PL1 and PL3 of the diets, were fed to cod larvae from 17 days post hatching (dph) to 45 dph.
In the liver, hepatocytes and their nuclei were smaller in NL1 larvae compared with the PL larvae; the mitochondrial membrane structures were less dense and the amount of lipids observed in the liver was significantly higher in NL1 larvae compared with the PL3 larvae. The liver and gut size was related to larval size, with no differences between the larval groups. The results demonstrated that the essential fatty acids were more beneficial for cod larvae when they were incorporated in the dietary polar PL rather than in the NL, and that the n-3 HUFA requirements in cod larvae is possibly higher than that in the PL1 diet.     

Reproduction,early development and larviculture of the barber goby,Elacatinus figaro (Sazima,Moura & Rosa 1997)

The barber goby, Elacatinus figaro, is a cleaner species of ecological importance and of keen interest to the aquarium trade. Endemic to Brazil, it is a threatened species and so aquaculture is a potential solution for reducing pressure on the natural stocks. This study describes the reproductive behaviour, the embryonic and larval development and the general breeding and rearing conditions. Ten wild fish initiated the formation of breeding pairs 20 days after acclimation to captivity. Spawning started 12 days after the first pair was formed, with one female from each pair spawning from 140 to 700 eggs (n=15 spawnings). The average period of incubation of the eggs was 6.8 days at 25 °C. The best hatching rate was 99.5% (n=10 spawnings). Larval rearing used Nannochloropsis oculata with rotifers (Brachionus rotundiformis) as the first food (day 0–25); nauplii and meta‐nauplii of Artemia were fed from day 18 until larval metamorphosis with subsequent weaning using commercial marine fish diets. The transformation to juveniles started at around the 30th day post hatch. The best larval survival rate until complete metamorphosis was 30.6% (n=4 larvicultures). After this period, the mortality was insignificant. This study demonstrated that the cultivation of barber goby is feasible.     

Optimization of treatment regimes for controlled sex differentiation and sterilization in wild rainbow trout (Salmo gairdneri Richardson) by oral administration of 17α-methyltestosterone

The oral administration of 17α-methyltestosterone (MT) to wild rainbow trout fry at concentrations ranging from 1 to 100 mg/kg diet for periods up to 120 days following swim-up produced male-female ratios substantially different from controls. 100% males were produced with low MT doses (1, 3 and 9 mg/kg diet) administered for 60 days. High proportions (79–90%) of sterile rainbow trout were obtained with greater doses of the steroid (25, 50 and 100 mg/kg diet) fed for 120 days. A paradoxical feminizing effect at high doses of MT (50 and 100 mg/kg diet) was observed irrespective of the length of the treatment. No dose-related mortality during the treatments was observed.     

Chemical surface disinfection of eggs of Baltic cod,Gadus morhua L.

The effect of two disinfectants on eggs and larvae of Baltic cod, Gadus morhua, was investigated. The eggs were disinfected for 10 min using various concentrations of either glutaraldehyde (100, 200, 400, 600 and 800 mg L^?1) or iodophor (10, 50, 100 and 150 mg L^?1), 1–4‐days post‐fertilization. Bactericidal effect of disinfection, survival to hatching, hatching success and larval abnormalities were assessed. Larval survival was recorded at 5‐, 10‐ and 15‐days post‐hatch (dph). Although Baltic cod eggs have an unusually thin chorion, they could tolerate surface disinfection. A reduction in bacterial growth was observed with increased concentrations of disinfectant (3.0 × 10⁷–1.6 × 10¹ CFU mL^?1). Abnormalities in newly hatched larvae were not related to disinfection. Survival of the yolk sac larvae was significantly better for eggs treated with 400 mg L^?1 glutaraldehyde for 10 min at 10 and 15 dph. Effective disinfection was also recorded using 100 mg L^?1 Actomar K30. Egg batch effect rather than initial bacterial concentration, disinfectant type or incubation method determined the survival of the eggs to hatching and survival of larvae. Because of the carcinogenic effect of glutaraldehyde, iodophor is recommended for routine disinfection of cod eggs.