封闭循环水系统和船体网箱驯养圆口铜鱼幼鱼的效果比较

以长江野生圆口铜鱼(Coreius guichenoti)幼鱼(约150~400 g)为试验对象,开展了封闭循环水系统和船体网箱驯养圆口铜鱼的比较试验。每种驯养条件下的试验鱼均按规格分2组进行驯养。封闭循环水系统中2组试验鱼的放养密度分别为11.48 kg/m3和17.65 kg/m3,驯养时间为279 d,平均水温为(14.5±3.4)℃。船体网箱中2组试验鱼的放养密度分别为4.40 kg/m3和7.06 kg/m3,驯养时间244 d,平均水温为(20.0±3.1)℃。所有试验鱼均采用人工配合饲料进行饱食投喂。结果显示,封闭循环水系统和船体网箱驯养试验鱼的成活率分别为97.75%和83.78%,且大规格试验鱼比小规格试验鱼成活率略高。封闭循环水系统中两组试验鱼的体重特定生长率分别为0.08%/d和0.11%/d,船体网箱中两组试验鱼的体重特定生长率分别为0.17%/d和0.21%/d。船体网箱试验鱼的丰满度总体大于封闭循环水系统的试验鱼。封闭循环水系统中全年未暴发重大疾病,船体网箱中暴发过一次较大规模的小瓜虫、车轮虫等寄生虫病。结果表明,封闭循环水系统驯养圆口铜鱼的成活率高但生长较慢,船体网箱驯养圆口铜鱼的生长优势明显但易遭受疾病侵袭。综合而言,封闭循环水系统和船体网箱养殖均是当前比较可行的圆口铜鱼驯养方式。     

圆口铜鱼子二代苗种的早期培育

正圆口铜鱼(coreius guichenoti)隶属鲤科、鱼句亚科、铜鱼属,是主要分布在长江上游的特有鱼类。有关圆口铜鱼的野生亲鱼繁殖、驯养及捕捞野生鱼苗驯养已有报道,而关于其子二代的苗种培育尚未有报道。本文通过蓄养圆口铜鱼自繁仔鱼早期培育的总结,旨在为该物种的保护提供借鉴。     

饥饿对圆口铜鱼Coreius guichenoti仔鱼早期发育的影响

在水温(22.0±1.0)℃条件下,研究饥饿状态下圆口铜鱼Coreius guichenoti仔鱼生长、初次摄食率、不可逆点(PNR)以及摄食节律。结果表明:圆口铜鱼初孵仔鱼全长(7.50±0.01)mm,卵黄囊体积(3.36±0.11)mm~3,摄食组仔鱼全长生长呈线性增加,饥饿组仔鱼生长呈先增长后下降趋势。早期仔鱼(5日龄)和晚期仔鱼(15日龄)的摄食节律相似,高峰在凌晨6:00和黄昏18:00,属于典型的晨昏摄食类型。1~3日龄仔鱼为内源性营养期;4日龄仔鱼开口摄食,进入混合营养期,初次摄食率约为25.1%;5日龄卵黄囊耗尽,进入外源营养期;7日龄仔鱼摄食率达到最高水平为100%,最高摄食率维持6d,PNR期为13~14日龄。在本实验水温下,圆口铜鱼仔鱼最佳投喂时间为4~6日龄。     

云纹石斑鱼(♀)×七带石斑鱼(♂)杂交子一代胚胎发育及仔稚幼鱼形态学观察

以云纹石斑鱼(Epinephelus moara)♀为母本,七带石斑鱼(E.septemfasciatus)♂为父本进行种间远缘杂交,系统观察了杂交子一代胚胎及仔稚幼鱼的生长发育及形态特征。对杂交子一代的胚胎发育按卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期各阶段进行观察,在水温21～22.5℃、盐度29、pH 8～8.1的海水中,整个胚胎发育过程经35 h 20min完成。根据在卵黄囊期、第二背鳍棘和腹鳍棘生长消退过程、鳞片生长、体表色素变化的不同,观察比较了胚后发育的仔鱼期、稚鱼期、幼鱼期形态特征。鱼苗培育至58 d后完成了稚鱼至幼鱼的变态:初孵仔鱼4 d以前为内源性营养(卵黄囊仔鱼);4 d后开口摄食,为外源性营养;(42±2)d基本完成变态进入稚鱼阶段,(58±4)d全身被鳞,进入幼鱼期。同时,用同一母本(云纹石斑鱼)同批卵与同种雄鱼采集的精子授精后获得的受精卵作为对照组,进行孵化和仔稚幼鱼培育,与杂交子一代进行比较,结果发现杂交子一代在仔稚幼鱼阶段生长速度快于云纹石斑鱼,与七带石斑鱼相近。     

棕点石斑鱼(♀)×鞍带石斑鱼(♂)杂交子代胚胎及仔稚幼鱼发育的跟踪观察

本研究阐述了棕点石斑鱼(♀)×鞍带石斑鱼(♂)杂交子代(简称珍珠龙胆石斑鱼)的胚胎发育和仔稚幼鱼形态发育的特征及其养殖过程中的一些难点、要点,以期为今后苗种的规模化培育生产提供参考依据。通过对珍珠龙胆石斑鱼各个发育期连续取样,系统观察并记录各发育期的形态变化及生长特征。结果表明,1)在水温27-28℃条件下,历时25 h 25 min孵化出膜,整个发育过程划分为卵裂期、囊胚期、原肠胚期、神经胚期和器官形成期。2)在水温(27.0±0.5)℃、盐度30、p H 8的培育条件下,根据卵黄囊、第二背鳍棘和腹鳍棘的生长与伸缩及鳞片、体色的变化将胚后发育分为仔鱼、稚鱼、幼鱼3个时期。仔鱼期根据卵黄囊的有无分为前期仔鱼和后期仔鱼。初孵至孵化后4 d为前期仔鱼;孵化后5 d,仔鱼卵黄囊完全消失,成为后期仔鱼;孵化后32 d,50%的仔鱼进入稚鱼期;孵化后46 d,50%的稚鱼完成变态,成为幼鱼。初孵仔鱼的全长平均为(1.65±0.11)mm,发育至70 d时,幼鱼平均全长已达(75.47±0.19)mm。跟踪观察的结果发现,珍珠龙胆石斑鱼作为杂交子代,从受精到发育的各阶段均能健康正常地生长发育,且生长快速、抗病力强,具有"虎斑头、龙胆尾"的外型,具有明显的杂交优势。     

圆口铜鱼人工驯养繁育进展与展望

圆口铜鱼(Coreius guichenoti)是长江上游渔业资源衰退的代表性物种,目前已被列为极度濒危物种,社会关注度空前。在圆口铜鱼自然繁殖条件几尽丧失的情况下,人工驯养繁育成为保护该物种的极重要选择。近年来,圆口铜鱼的人工驯养繁殖技术取得了一些突破性进展,对圆口铜鱼的保护管理具有重大意义。本文总结了圆口铜鱼养殖生物学、人工驯养与繁育技术的研究进展,分析了存在的主要问题,并针对性地提出解决建议。     

饥饿对条石鲷仔稚鱼生长发育的影响

采用实验生态学方法研究了饥饿对条石鲷仔稚幼鱼的影响.结果表明,水温18、22和26 ℃时,初孵仔鱼的PNR点分别出现在6～7 d、6～7 d和4～4.5 d.仔鱼开口摄食时间随温度降低而滞后,22 ℃时初次摄食率最高,26 ℃时初次摄食率降至50%以下.温度对仔稚幼鱼耐饥饿的能力影响明显,18和22 ℃时,前期仔鱼半数死亡时间为4～5 d,而13日龄仔鱼半数死亡时间为2.5 d,24日龄稚鱼的为1.5～2 d,实验鱼饥饿3 d后,大部分已经不能恢复摄食.在26 ℃时,前期仔鱼和13日龄仔鱼的半数死亡时间为1.5 d,24日龄稚鱼为2～2.5 d,而45日龄幼鱼在22和26 ℃时半数死亡时间都为6 d,表明随着生长发育,苗种对饥饿耐受能力明显增强.饥饿对条石鲷幼鱼的生长影响显著(P＜0.05),饥饿条件下的仔鱼全长和体重增加远远低于对照组,甚至出现体重的负增长,30日龄幼鱼在饥饿条件下的体重损失率达到50%以上,而45日龄幼鱼饥饿后的体重损失率约为10%,13日龄仔鱼阶段是条石鲷早期生长发育阶段中较为敏感的阶段.     

许氏平鲉仔、稚鱼的摄食特性及幼鱼胃排空率

为阐明人工育苗条件下许氏平鲉早期发育阶段的摄食特性及变化规律,采用实验生态学方法,对人工育苗条件下许氏平鲉仔、稚鱼摄食特性及不同生长阶段幼鱼的胃排空率进行了研究。结果显示,许氏平鲉仔、稚鱼已具有较强的摄食能力,前期仔鱼(2日龄)昼夜摄食高峰出现于16:00;后期仔鱼(15日龄)与稚鱼(25日龄)的摄食高峰均出现在16:00—20:00,表现为白天摄食类型。许氏平鲉仔、稚鱼各阶段的日摄食率分别为42.26%(2日龄)、16.25%(15日龄)和13.07%(25日龄),可将其作为许氏平鲉早期发育阶段日投喂量的参考标准。在水温(22±0.5)°C条件下,摄食人工配合饵料的不同规格许氏平鲉幼鱼(平均体质量1.78和8.52 g)表现出明显不同的胃排空特征。采用线性模型、指数模型、平方根模型和Logistic模型均能较好地拟合实验幼鱼的胃排空数据。以R2、RSS、SDR为标准进一步比较,结果显示,体质量1.78和8.52 g幼鱼胃排空最佳拟合模型分别为线性模型和Logistic模型,其胃排空率分别为0.007和0.047 g/h,根据其胃排空特征以及投喂频率对幼鱼生长离散的影响等,建议将饱食投喂2~3次/d作为60~90日龄幼鱼的适宜投喂频率。     

不同的转食饵料对圆口铜鱼幼苗生长及存活的影响分析

采用丰年虫、水蚯蚓、微囊饲料3种饵料的不同配合策略,对圆口铜鱼仔稚鱼投喂60 d,以研究对其生长和存活率的影响。结果显示,30日龄后投喂水蚯蚓的成活率、全长、体长、体质量均高于其他组,特定生长率为4.44%±0.30%/d,显著高于对照组和W15微囊饲料组。15日龄后转投微囊饲料组的全长、体长、体质量和特定生长率最低。结果表明不同的转食策略对圆口铜鱼仔稚鱼的生长及存活有显著的影响,30日龄后投喂水蚯蚓能有效的提高存活率及生长速度。     

圆口铜鱼小瓜虫病的预防策略

<正>一、圆口铜鱼易感染小瓜虫病的主要原因1.生理特点淡水有鳞鱼中比较容易感染小瓜虫病的一些鱼,一般都有细小疏松的鳞片,如:圆口铜鱼、岩原鲤(幼鱼)、厚颌鲂等,而胭脂鱼、中华倒刺鲃、白甲鱼等鱼因为有紧密的鳞片保护,不容易寄生感染小瓜虫病。此外,圆口铜鱼丰富的皮下脂肪层或许更容易成为小瓜虫安居的"温床"。2.应激反应圆口铜鱼的驯养,业内公认有三个最主要的技术难点:应激反应、性腺发育及鱼病危害(主要是小瓜虫病)。笔者认为,应激反应与感染小瓜虫病之间存在一定的因果关系,即应激反应强的鱼类易感染小瓜虫病。容易引起圆口铜鱼应激反应     

不同驯化方式对哲罗鱼仔、稚鱼生长和存活的影响

在水温8．9～14．2℃下，在平列糟（长3m，宽0．4m，高0．2m）中采用A、B和C组三种投喂方式驯养刚开口摄食、体质量0．129±0．07g的哲罗鱼（Huchotaimen）苗60d，以探讨驯化方式对哲罗鱼仔、稚鱼生长、存活和种群变异系数的影响：A组以浮游动物开口，投喂浮游动物3d，投喂水蚯蚓15d后，改投人工饲料；B组以水蚯蚓开121，投喂水蚯蚓15d后，改投人工饲料；C组直接以人工饲料开口。结果表明：C组体质量特定生长率（3．577±0．78％／d），明显大于A组（3．132±0．87％／d）和B组（3．024±0．91）；A、B、C组的成活率分别为75．67％、74．87％和84．36％，C组明显大于A、B组；A、B和c组鱼体质量变异系数依次为21．47％、22．59％和11．32％，实验表明，直接以人工饲料开口是哲罗鱼规模化养殖中合理的驯化投喂模式。     

Selenium supplementation changes glutathione peroxidase activity and thyroid hormone production in Senegalese sole (Solea senegalensis) larvae

Dietary selenium (Se) influences the glutathione peroxidase (GPx) activity and the thyroid hormone system in vertebrates, but these relations are poorly described in fish. The present study aimed to evaluate the effect of Se supplementation on Senegalese sole larvae, focusing on GPx activity and thyroid status. Two groups of larvae were fed on either control (C) or Se‐enriched live feed, from 2 days after hatch (DAH) until 34 DAH. Senegalese sole larvae fed Se‐enriched live feed significantly increased their whole‐body Se, compared to larvae from C group. The activity of GPx was higher in larvae from Se group, suggesting that the levels of this mineral were suboptimal in the control diet. TH levels were also higher in larvae fed Se‐enriched live feed, suggesting that Se may have a positive influence on the TH production in early life stages of marine fish larvae.     

Determination of the optimum transfer time of kutum (<Emphasis Type="Italic">Rutilus frisii kutum</Emphasis>) larvae from live food to artificial dry feed

Kutum Rutilus frisii kutum is known as a valuable commercial species in the southern part of Caspian Sea. Artificial rearing of fry has been introduced as an alternative to supply kutum fry in order to restock the kutum population in the Caspian Sea. The aim of this study was to find the suitable time to transfer kutum larvae from live food to artificial feed. The experiment began on day 3 post- hatching and lasted for 21 days. Mean initial weight of larvae was 4.5 mg. Five experimental groups including Group A (zooplankton alone for 21 days), Group B (12 days zooplankton + 9 days artificial feed), Group C (8 days zooplankton + 13 days artificial feed), Group D (4 days zooplankton + 17 days artificial feed) and Group E (artificial feed alone for 21 days) were considered for this experiment. According to the obtained results, the specific growth rate of kutum larvae varied from 8.01 to 13.58% day⁻¹, and the highest and lowest specific growth rate were found in A and E treatments, respectively. The lowest mean body weight (24.6 mg) was found in larvae fed on artificial feed for 21 days. However, survival rates of kutum larvae fed mixed zooplankton for 8 and 12 days (85.83 and 89.33%, respectively) were comparable with those of larvae fed live food during the entire experiment (91.6%). The lowest survival rate (69.16%) was found in larvae fed artificial feed during the entire experiment.     

配合饲料投喂量和粒径对绿盘鲍稚鲍生长和存活的影响

在水温15.8～24.7℃下,将小规格(壳长为1.03±0.02 cm)和中规格(壳长为1.57±0.03 cm)绿盘鲍(GS-02-003-2018)(皱纹盘鲍Haliotis discus hannai Ino♀×绿鲍H.fulgens♂)稚鲍分成A、B、C和D 4个组,饲养在240 mm×170 mm×285 m...     

Draining system and feeding rate during the initial development of Lophiosilurus alexandri (Steindachner, 1877), a carnivorous freshwater fish

This study evaluated the efficiency of the drainage system during the larviculture of Lophiosilurus alexandri. Moreover, we assessed the best feeding rate after feed training for juvenile production. The study was performed in three phases over 87 days. In phase 1 (40 days), larvae were fed live food and posteriorly submitted to feed training in two drainage systems: water drained on the surface (DS), and water drained into a tank column (DI). In the second phase (30 days), using only the DS system juveniles were fed a formulated diet at feeding rates, 2, 4, 6 and 8% of body wet weight. In the third phase (17 days), the fish from the second phase were fed until apparent satiation. At the first phase, the animals in the DS system exhibited greater survival rates and growth. The best feeding rate for daily weight gain, specific growth rate (SGR) and mean body weights were similar: 5.57, 5.13 and 5.68% respectively. In the third phase, an increased SGR was observed in the treatment groups that received lower feeding rates in the second phase (2 and 4%), which could indicate a possible compensatory growth rate.     

Effect of feed restriction on the growth performance of turbot (Scophthalmus maximus L.) juveniles under commercial rearing conditions

Two trials were performed to study the effect of periodic feed deprivation (trial 1) or feed restriction, followed by satiation feeding (trial 2) on the growth performance of turbot juveniles under commercial rearing conditions. In trial 1, duplicate groups of 350 fish with an initial weight of 62 g were fed a commercial diet to apparent visual satiation for 7, 6, 5 or 4 days a week for 83 days. At the end of the trial, fish weight was directly related to the number of feeding days but feed efficiency and protein efficiency ratio were not affected by treatments. At the end of the trial, there were no differences in whole‐body composition among groups. In trial 2, duplicate groups of 500 fish with an initial weight of 33 g were fed a commercial diet to satiation (100%) or feed restricted to 90%, 80% and 70% of satiation for 90 days. Thereafter, all groups were fed to satiation for 34 days. During the feed restriction period, growth was directly related to feed intake, while during the satiation feeding period, it was inversely related to the previous feeding level. At the end of the trial, the final weight was not different among groups. At the end of the feed restriction period, whole‐body lipid content showed a trend to decrease with an increase in the feed restriction level. The results of this study indicate that under practical conditions, turbot juveniles should be fed daily as even cycles of short periods of feed deprivation negatively affect growth, while not improving feed efficiency. On the contrary, even after a relatively long feed restriction period, fish shows compensatory growth, and this may be used as a feed management strategy for controlling fish production in commercial farms.     

Evaluation of Live Feeds for Larval and Postlarval Mahimahi Coryphaena hippurus

Live hatchery feeds were assayed for fatty acids (FA), amino acids (AA), and their ability to support growth and survival of larval and postlarval mahimahi Coryphaena hippurus at two different hatchery stages. Euterpina acuritrons copepods (C), mahimahi yolk-sac larvae (YSL), Artemia parthenogenica brine shrimp nauplii (BSn), A. parthenogenica juveniles (BSj), and Brachionus plicatilis rotifers (R) were assayed, using several enrichment media. There was little difference in AAs among feeds.
Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were about 10 times higher in YSL than in their feeds. This explains previous findings where first stage larval survival (0–9 days) was not affected by feed HUFA levels. Second stage survival was significantly higher when larvae were fed copepods. Enrichment with 100 ppm SuperSelco greatly improved the survival of larvae that were fed brine shrimp. The even higher omega-3 fatty acids found in copepods appear to be important for survival of larvae under more stressful conditions.
Brine shrimp juveniles enriched with SuperSelco are a good food for postlarval mahimahi. Yolksac larvae of mahimahi are an even better food, promoting faster growth at less cost, for large scale mahimahi aquaculturists. Different batches of yolksac mahimahi larvae varied by a factor of 10 in their concentration of DHA, but always had the highest level of DHA as much as 40% of total fatty acids (FAs). These "high HUFA" batches of YSL also had the highest levels of EPA and total fatty acids. The data suggest that climate and broodstock age may have considerable influence on larval nutrition.     

Spirulina meal has acted as a strong feeding attractant for Litopenaeus vannamei at a very low dietary inclusion level

The present work aimed at studying the growth performance and feeding preference of Litopenaeus vannamei juveniles fed on diets supplemented or not with Spirulina meal. Litopenaeus vannamei juveniles (3.89 ± 0.25 g) were stocked for 72 days in 28 round 500‐L tanks at 44 shrimp/tank (77 juveniles/m²). The diets were supplemented with 0.5% of a commercial feed attractant (C25 and C50) or with Spirulina meal (S25 and S50). In C25/S25 and C50/S50 there were reductions of 25% and 50% in fishmeal inclusion level respectively. In a further study, two feeding trays with different diets were allowed to shrimp at the same moment and they were located in opposite walls of the tank. The feed remains in each feeding tray were collected and weighted to calculate the dry feed remains. The weekly growth rate of shrimp fed on S25 (0.89 ± 0.03 g) was not significantly different from those fed on C25 (0.89 ± 0.01 g). The attractiveness experiment showed that S25 was preferred significantly more by shrimp than C25. In conclusion, Spirulina meal added at 0.5% in a complete diet for L. vannamei juveniles, with 14% of Peruvian fishmeal, has proved itself as a nutritionally efficient feeding attractant.     

Growth and survival of first-feeding spotted wolffish (Anarhichas minor Olafsen) at various temperature regimes

In order to define temperature regimes that could benefit successful production of spotted wolffish (Anarhichas minor) juveniles, experiments with offspring from two different females were carried out. The larvae were fed a new formulated feed or a commercial start‐feed for marine fish, both of which have given high survival rates. In the first experiment newly hatched larvae were fed at constant 6 °C, 8 °C, 10 °C and 12 °C as well as at ambient seawater temperature (2.9–4.5 °C) during 63 days. High survival, 90% to 96%, was registered at ambient and most constant temperature regimes, whereas in the 12 °C groups survival was reduced to 80%. Growth rate (SGR) was very low, 1.8% day^?1, at the low ambient temperatures. Growth rate was positively correlated with temperature and varied between 3.1% day^?1 to 4.7% day^?1, from 6 °C to 12 °C. In the second experiment, set up to include potential detrimental temperatures and study beneficial effects of a more restricted, elevated first‐feeding temperature regime, the larvae were fed at constant 8 °C, 10 °C, 12 °C, 14 °C and 16 °C until 30 days post hatch, followed by constant 8 °C for the next 33 days. In this experiment, low survival, 25% and 2.0%, was registered at 63 days post hatch when larvae were reared initially at 14 °C and 16 °C respectively. The survival of the larvae at the other temperature regimes varied from 47% to 64%, highest survival rate (64%) was found at 8 °C. The lowest specific growth rate, 2.6% day^?1, was noted in the 16 °C group. At constant 8 °C to 14 °C (regulated to 8 °C), the SGR varied from 4.45% day^?1 to 5.13% day^?1. The larvae grew faster in the experiment when initially comparable temperatures (8 °C, 10 °C and 12 °C) were regulated to constant 8 °C after 30 days compared with the first experiment where feeding was carried out at the same constant temperatures (8 °C, 10 °C and 12 °C) during the whole experimental period.     

Growth performance and survival of giant freshwater prawn Macrobrachium rosenbergii larvae fed coloured feed

This study examined the behavioural response on the preference and acceptance, growth performance and survival of Marcobrachium rosenbergi larvae fed with isonitrogenous and isolipidic yellow (YCF) and blue (BCF) coloured feed. In the behavioural response test, single and paired feed drop test of YCF and BCF were introduced at the middle of a tank about 15–20 cm from the edge of the white colour tank wall to larvae zoea IV–VI. The number of larvae attracted to each coloured feed was recorded. For the growth and survival performance, each coloured feed was fed to triplicate groups of larvae (zoea V–VI) at stocking density of 30 larvae/L in 12 ppt brackish water for 28 days until they reached postlarval (PL) stage. In the behavioural test, the number of larvae that attracted and accepted the BCF was significantly higher than those fed YCF (p < 0.05). The body weight and length of PL fed BCF was 28% and 5.6% bigger than those fed YCF respectively. However, the survival of the PL was almost similar in both treatments. This study shows that the freshwater prawn larvae were attracted more to the BCF and able to detect and capture the preferred BCF by vision and this contributed to higher growth of the larvae.