Effect of temperature and phytoplankton concentration of Partitioned Aquaculture System water on freshwater mussel filtration

The freshwater mussel Elliptio complanata was provided green algal‐dominated water from a Partitioned Aquaculture System (PAS) over a range of water temperatures (6.1–32.4 °C) and suspended particulate organic carbon (POC) concentrations (<1–32.2 mg C L^?1) to determine filtration rates as mg POC kg^?1 wet tissue weight h^?1. The lowest filtration rates were observed at lowest temperatures and POC concentrations while the highest rates were at intermediate temperatures and the highest POC levels. The predicted filtration rate (PFR) in response to water temperature and POC concentrations was as follows: ln PFR=1.4352+0.1192 POC+0.1399 T?0.0001 T³. Within the experimental conditions, PFRs at any POC concentration increased with increased water temperature to a peak at 22 °C and then decreased. The maximum PFR occurred at 22 °C and 32 mg C L^?1 and the minimum PFR at 7 °C and 1 mg C L^?1. A model to describe the mussel filtration rate responses to PAS water conditions involves both water temperature and POC concentration.     

Effects of feeding rates on growth and production of Nile tilapia, common carp and silver carp polycultured in fertilized ponds

Abstract In an attempt to identify appropriate feeding rates for multispecies of fish raised in fertilized earthen ponds, the present work was conducted over a 19‐week experimental period to establish the growth performance, production and body composition of Nile tilapia, common carp and silver carp fed 0.0%, 0.5%, 1.0%, 3.0%, 5.0% biomass and to apparent satiation (treatments). Twelve ponds were stocked with a similar number and weight of each fish species. Two ponds were assigned to each of the treatments, and a 25% protein pelleted fish feed was used to feed fish at the specified rate of feeding. At the end of the experiment, growth, weight gain, survival, yield and body composition of fish groups were affected by the treatments. The economic effectiveness also varied among treatments. The most conspicuous attribute of the feeding rates was its lack of influence on growth (g day^?1), weight gain (g per fish), yield (kg ha^?1) or body composition of silver carp. The results of whole‐body proximate analysis indicated that various feeding rates had either an irregular pattern or no effects on the protein and ash gain per 100 g of fish body weight (bw) gain. The most notable exceptions were significant (P < 0.05) increases in body fat and gross energy gains in Nile tilapia, common carp and silver carp accompanied by decreases in percentages of moisture (but not in silver carp) as feeding rate increased. Among the six different feeding levels, feeding to apparent satiation (feed amount was equivalent to 2.67% of fish bw day^?1) appeared to be optimal, as it significantly (P < 0.05) supported the highest fish production, income and net profit compared with all other treatments except for the 3% feeding level, for which the differences in those measurements were comparable.     

Effect of Nile tilapia, Oreochromis niloticus (L.), size on phytoplankton filtration rate

Four different‐sized (390±3, 140±2, 40±2, 16±1 g) Nile tilapia, Oreochromis niloticus (L.), stocked at the same biomass in timed pulse feeding chambers were provided 27–29°C water dominated by Microcystis (82%) and Scenedesmus (18%) to determine the effect of fish size on filtration rates. The number of Microcystis and Scenedesmus units filtered from the water decreased significantly with increasing tilapia size. The shaping constants and maximum filtration rates for Ivlev's feeding model used to describe the relation between filtration rates and the suspended particulate organic carbon (POC) concentrations were significantly different among the four sizes. Filtration rates of 763, 671, 512 and 300 mg C kg^?1 h^?1, which correspond to 70%, 82%, 86% and 90% saturation levels, were achieved at POC levels of 30, 32, 32 and 33 mg C L^?1 for 16, 40, 140 and 390 g Nile tilapia respectively. Smaller tilapia achieved these rates at lower POC concentrations than larger tilapia.     

Effect of temperature and phytoplankton concentration on Nile tilapia Oreochromis niloticus (L.) filtration rate

Nile tilapia Oreochromis niloticus (L.) held in timed‐pulse feeding chambers, were provided with algal‐rich water dominated by either green algae (Scenedesmus, Ankistrodesmus, Chlorella and Tetraedron) or cyanobacteria (Microcystis) to determine the effect of temperature and phytoplankton concentration on filtration rates. Green algae and cyanobacteria filtration rates were measured as suspended particulate organic carbon (POC) kg^?1 wet fish weight h^?1. Ivlev's filter‐feeding model described the relationships between filtration rates and suspended POC concentration of green algae and cyanobacteria. Filtration rates of both green algae and cyanobacteria increased linearly as water temperature increased from 17 °C to 32 °C and were significantly higher in the warm‐water regime (26–32 °C) than in the cool‐water regime (17–23 °C). Filtration rates at 95% saturation POC (FR₉₅) in green algal and cyanobacterial waters were 700 mg C kg^?1 h^?1 and 851 mg C kg^?1 h^?1 in the warm‐water regime and 369 mg C kg^?1 h^?1 and 439 mg C kg^?1 h^?1 in the cool‐water regime respectively. The FR₉₅ in warm water were achieved at lower POC concentrations than in cool water.     

长江中下游鲢、鳙、草鱼、青鱼种群分化的同工酶分析

为查明长江中下游鲢、鳙、草鱼、青鱼有无不同种群，用聚丙烯酰胺凝胶电泳测定了长江中游天鹅洲故道、汉阳、瑞昌江段和下游安庆江段鲢、鳙、草鱼、青鱼各４个群体间的生化遗传变异。同种鱼各群体间的遗传变异未见有显著差异。遗传距离Ｄ值均小于０．００１。由此，初步认为长江中下游的鲢、鳙、草鱼、青鱼应各属一个没有显著遗传分化的种群，我们称之为“长江种群”。因而，在长江中下游选择一处优良保护场所就有可能达到就地保护长     

长江鲢、鳙、草鱼和青鱼原种亲鱼标准与检测的研究

主要报导长江原种亲鱼鲢、鳙、草鱼和青鱼的形态特征、年龄生长和繁殖特性。通过可数可量参数的测定，年龄生长、性成熟年龄、繁殖力、成熟系数及卵比重等单项的相对关系的研究，讨论并提出了原种亲鱼鲢、鳙、草鱼、青鱼的标准参数，可供原种场生产管理、原种检测及种质资源保护的依据。     

High fry production rates using post-thaw silver carp (Hypophthalmichthys molitrix) spermatozoa under farming conditions

Silver carp (Hypophthalmichthys molitrix) is not endemic to Cuba, and egg fertilization is totally artificial; males produce spermatozoa only between March and October. Cryopreservation of silver carp spermatozoa would reduce the number of males needed, minimize handling stress through less frequent stripping, and facilitate artificial propagation when eggs are available. The effects on motility and fry production from eggs fertilized with thawed sperm under farm-conditions were examined in this study. Five, seven and ten percent of dimethyl sulfoxide (DMSO), glycerol and methanol were tested as cryoprotectants. DMSO was a more suitable cryoprotectant than methanol or glycerol. The effect of equilibration time on the motility rate at 10% DMSO was evaluated. Hatching rates equal to the control (P>0.01) were obtained under farm conditions with frozen spermatozoa, stored even for a year in liquid nitrogen, with a final DMSO concentration of 10%. Cryopreservation offers a useful routine method for sperm storage and silver carp handling. To our knowledge, this is the first report on the production of fry from post-thaw silver carp spermatozoa under farming conditions.     

The eyes of the common carp and Nile tilapia are sensitive to near-infrared

Fish biologists have shown little interest in near-infrared (NIR) sensitivity because water absorbs light in the red and near-infrared and because downward irradiance in clear ocean water is mostly blue light. In recent years, however, Nile tilapia Oreochromis niloticus was shown to be NIR sensitive by behavioral techniques. This study confirmed NIR sensitivity in the common carp Cyprinus carpio and Nile tilapia by using a more sensitive technique than a behavioral one. Cardiac conditioning experiments showed that both fishes are sensitive to 865 nm NIR. The conditioned response to 865 nm NIR was observed in Nile tilapia when the eyes were not covered and the pineal window was covered, but not when the same fish had its eyes covered and the pineal window exposed to the NIR. The eyes are thus, the NIR-sensitive organs in Nile tilapia. To identify the NIR photoreceptor, the retina was examined by histology. The retina exposed to 865 nm NIR showed incomplete dark adaptation with rods exposed from retinal epithelial pigment. Though the reaction to NIR seemed to be mediated mainly by the red cone, the involvement of the rod could not be ruled out.     

银鲫与普通鲫群体遗传结构的比较分析

利用15个微卫星多态性分子标记,对黑龙江省方正县双龙水库和双凤水库两个水体的雌核发育银鲫(Car-assius auratus gibelio)和二倍体普通鲫(Carassius auratus(L))的群体遗传多样性进行比较分析。结果显示:平均每个多态性位点获得银鲫10.39个有效等位基因,普通鲫11.82个有效等位基因;双龙水库三倍体银鲫和二倍体普通鲫的平均观测杂合度分别为0.6035和0.6300,双凤水库中的三倍体银鲫和二倍体普通鲫的平均观测杂合度为0.5311和0.5885;相似性与遗传距离分析结果显示:相似性最大的是双凤水体内的银鲫和普通鲫(0.8127),远大于两个水体间的银鲫群体间的相似性。结果表明,银鲫与普通鲫存在着明显的遗传物质交流,较高的遗传相似性不仅与传统的银鲫起源于普通鲫的观点一致,也暗示银鲫与普通鲫存在经常性地遗传物质交流。     

Effects of silver carp and small indigenous species on pond ecology and carp polycultures in Bangladesh

A sustainable semi-intensive pond aquaculture technology including major carp species as cash-crop and small indigenous fish species (SIS) as food for the farmers' families is being optimized in Bangladesh. The inclusion of silver carp (Hypophthalmichthys molitrix), a cheap large species affordable by poor farmers, is now being considered. As part of a study on the effects of this filter feeder on polycultures including the large carps rohu (Labeo rohita), catla (Catla catla) and common carp (Cyprinus carpio) and the SIS punti (Puntius sophore) and mola (Amblypharyngodon mola), an experiment was carried out to test the effects of silver carp and of each SIS species on the growth, survival and yield of the large and small fish and on pond ecology.The ecology of the ponds was dominated by changes in time, strongly related to the development of a surface plankton scum at the beginning of the culture season and weather conditions. The surface scum increased decomposition processes and decreased algal development in the water body, promoted photosynthesis and ammonium release and reduced nitrification. Over those effects, the presence of silver carp in the ponds decreased algal biomass through grazing and promoted nitrification providing and resuspending particles in the water column. These effects were also produced by mola, but were evident only in the absence of silver carp. Punti stirring on the pond bottom increased nutrient flow from the sediments into the water column and promoted nitrification, but were also evident only in the absence of silver carp.The addition of 10 silver carp over the 99 large carps stocked in the 100 m² fishponds did not affect punti and mola reproduction in the ponds, negatively affected rohu and catla growth and yield by about 20-25% but not their survival, did not affect common carp performance, reduced punti harvested biomass by 10%, reduced mola performance by about 50%, and silver carp's own biomass increased total yield and total income in about 20% each. The addition of 250 mola or punti to the large carp polycultures did not affect the performance of any of the large carps. The decreased income from selling the more expensive large carps was more than compensated by that obtained from silver carp, which increased total income by 13-24% as compared to the corresponding treatments without silver carp. This allows the option to the farmer of selling part of the silver carp to complete the cash income that would have been obtained from large carps only if silver carp would not be stocked, and consume the rest with the family.     

Influence of recooking on volatile and non-volatile compounds found in silver carp Hypophthalmichthys molitrix

Volatile and non-volatile compounds, which contribute to flavor in raw fish, were compared in raw, cooked and recooked silver carp. In total, 20, 34 and 34 volatile compounds, including aldehydes, alcohols, ketones, hydrocarbons and heterocyclic compounds, were identified in raw, cooked and recooked samples, respectively. Cooking the samples resulted in a significant increase in volatile compounds and the formation of new aldehydes, alcohols, ketones, hydrocarbons and heterocyclic compounds. In addition, the content of free amino acids (FAA) decreased dramatically, and the amount of nucleotides and small peptides significantly changed. With recooking of the samples, the levels of most of the volatile compounds decreased significantly, and there was a substantial change in nucleotides and small peptides. However, the effect of recooking on FAA was not observable.     

转基因"超级鲤"F2代与松浦鲤的耗氧率及窒息点的比较研究

通过转外源生长激素基因"超级鲤"F2代与松浦鲤的耗氧率与窒息点的比较试验证明在水温为18.0±1℃、鱼体重为84.5±1g时,"超级鲤"F2代的耗氧率是174.65±23.43mg/h.l,松浦鲤的耗氧率是257.98±19.25mg/h.l,经T检验(|T|=8.2067;df=8;双侧p＜0.01),"超级鲤"F2的耗氧率极显著地小于松浦鲤的耗氧率.耗氧率与水温或体重的变化关系均是随着水温的升高而升高,随着体重的增加而降低.F2代与松浦鲤的耗氧率昼夜变化曲线在走向上基本一致,高峰是在1030时和2030时,低谷是在1830时和030时.在同一水温条件下,F2代与松浦鲤窒息点的差异性随着鱼体重的增加而趋于显著.在水温为18.0±1℃条件下,当鱼体重为84.5±1g时,"超级鲤"F2代窒息点为0.1318mg/l,松浦鲤窒息点是0.1203mg/l,经T检验(|T|=2.775;df=2;双侧p=0.1090＞0.05)差异性不显著;当体重为108.5±1g时,F2代窒息点为0.1937mg/l,松浦鲤窒息点是0.1443mg/l,经T检验(|T|=8.296;df=2;双侧p=0.0142＜0.05)差异性显著.这两种鱼的窒息点与体重的变化关系一样,都是随着体重的增加而增加.     

大伙房水库鲢鳙的生长及生长模型_

根据灰色系统理论，建立了拟合鱼类生长的灰色动态生长模型，并应用这一模型和一般ＶＢＧＦ及特殊ＶＢＧＦ拟合了大伙房水库鲢鳙的体长生长和体重生长。这三个模型拟合鲢的体长生长的残差平方和分别产７．７７、８．５６、１８１５．９，拟合链的体重生长的残差平方和分别是０．０７、０．１５、５３．８８，拟合鳙的体长生长的残差平方和分别是２．４７、５．４９、２２９５．３，拟合鳙的体重生长的残差平方和分别为１．０５、０．     

津鲢与长江鲢遗传多样性分析

随机选取津鲢和长江鲢各36尾,用16个微卫星标记进行遗传多样性分析。结果显示:16个微卫星位点在2个群体中共检测到等位基因105个,基因型241种,每个位点等位基因数3～15个,平均6.6个,基因型4～37种,平均15.1种。2个鲢群体平均观察杂合度(Ho)分别为0.5393和0.5392,平均期望杂合度(He)分别为0.5887和0.5762,结果表明该2个鲢群体遗传多样性水平较高。2个鲢群体平均多态信息含量(PIC)分别为0.5602和0.54,固定系数(FIS)表明这2个鲢群体表现为杂合子缺乏(FIS0)。2个鲢群体之间的遗传距离为0.0566,平均遗传分化系数(Fst)值为0.021,说明仅有2.1%的遗传变异来源于群体间。     

’95溢洪对大伙房水库鲢、鳙渔业造成损失的估测

根据１９９０、１９９８年鲢、鳙渔获物的年龄组成,相关成份的放养尾数及１９９５年后的历年捕获量,结合可捕群体、补充群体等假设条件,利用修正的“恒定参数系统法”拟合分析了１９９５年溢洪后大伙房水库鲢、鳙的残存率、死亡系数、回捕率,探讨了′９５溢洪对该水库鲢、鳙渔业的影响,并根据理论捕获量推算出溢洪造成的损失分别为鲢２５０～３５０ｔ,鳙２３７～４３６ｔ。     

分隔池塘养殖系统研究进展与发展趋势

分隔池塘养殖系统是绿色高效池塘养殖设施研究发展的重点方向之一。提出了分隔池塘养殖系统的定义,阐述了系统设计的原理和国内外发展历程,归纳了标准分隔池塘、简易分隔池塘和流水槽池塘3种国外发展的主要系统模式类型,通过文献收集和实地调研对3种系统模式的研究进展和发展趋势进行了系统的梳理,比较了国内外发展模式的养殖品种、水循环方式、研究概况和产业应用情况,通过进一步讨论分级序批养殖池塘、跑道池养殖池塘2种在国内具备良好发展前景系统模式的优缺点,提出了下一步的研究重点和发展方向,为分隔池塘养殖系统的结构优化和技术提升提供参考。     

Suppression effect of LHRH-A and hCG on Piwi expression in testis of Nile tilapia Oreochromis niloticus

Piwi proteins as constituent factors of the piRNA pathway are required for germline maintenance,meiosisand gonad development.Previous study showed hCG could regulate the Piwi expression in ovary of teleosts.In this study,we revealed effects of LHRH-A and hCG on Piwi expression in testis of tilapia usingReal-time PCR and Western blot.Both in vivo and in vitro study suggest that LHRH-A and hCG significantlydown-regulated Piwil-1 and Piwil-2 in mRNA or protein levels compared with controls.Meanwhile,tissueand cell distribution showed that Piwi proteins were mainly expressed in spermatocytes rather thanmature sperms.These results indicated thatHPG suppressesPiwiswhich mayplayacrucialrolein testisdifferentiation and development.     

白鲢鱼糜低气味本底模型的构建研究

鱼糜制品(如火锅鱼丸)的风味是消费者关心的质量属性之一,而关键气味活性物质的吸附释放规律并不明确。现有气味研究主要在配置溶液中进行,与真实的气味活性物质—固态鱼糜之间的相互作用存在一定差异,因此,基于固态鱼糜进行气味研究是十分必要的,其关键在于一个无气味或低气味的鱼糜本底模型,从而可进一步研究各气味成分与鱼糜本底模型的互作关系。本研究考察了8种不同漂洗介质对鱼糜本底模型气味残留的影响。结果表明,白鲢(Hypophthalmichthys molitrix)鱼糜经SPME-GC-MS共检出65种挥发性物质,气味活性物质(OAV>1)有18种;经8种漂洗介质处理后,鱼糜样品中分别含有6、8、7、9、6、12、9和9种气味活性物质,挥发性气味物质的残留率依次为(0.380±0.120)%、(0.610±0.086)%、(0.280±0.033)%、(0.480±0.037)%、(0.150± 0.018)%、(4.330±0.160)%、(18.680±0.081)%和(0.490±0.003)%。综合SPME-GC-MS、电子鼻和感官评价结果比较,1% NaCl (W/W) + 1% Na2CO3 (W/W) + 4.0% C2H5OH (V/W)漂洗介质处理后,白鲢鱼糜的挥发性气味物质残留少,总含量降低为(6.57±0.77) μg/kg,17种气味活性物质的OAV<1,仅壬醛的OAV为1.34±0.05,可构建出低气味的鱼糜本底模型。     

鲢鳙杂种亲本连锁图标记加密和共线性比较

鲢(Hypophthalmichthys molitrix)与鳙(Aristichthys nobilis)杂种的养殖性能优于亲本,在水产养殖中利用广泛.为促进鲢、鳙遗传资源管理、经济性状定位等研究,已构建了鲢鳙种间杂种亲本的遗传连锁图,但图谱以AFLP标记为主,利用范围有限.为提高图谱质量和可用性,本研究采用新开发的微卫星标记加密了鲢鳙杂种亲本连锁图.雌性亲本鲢的连锁图标记总数从153增加到288(包括新开发微卫星标记93个),雄性亲本鲢的连锁图标记总数从271增加到511(包括新开发微卫星标记136).鳙图谱总长度从852.0 cM增加到965.8 cM,鲢图谱总长度从952.2 cM增加到1049.6 cM.鲢、鳙图谱共线性比较甄别出22个同缘连锁群,标记排列只存在轻微重排现象.亲本间共享的76个微卫星标记界定的标记间隔总长度在亲本间无差异(雌:雄＝1:1),与鳞鲢种内杂种亲本共享微卫星标记界定间隔的总长度雌雄比(1:0.45)显著不同.与模拟自然受精(种内杂种)相比,混精受精(种间杂种)可增加雄性亲本基因组范围的重组率.鲢鳙形态相似,染色体组型相同,杂种可育,鲢鳙杂交对重组率没有影响或影响很小.根据研究结果,认为混精授精回避了精子竞争,强化了全基因组重排,不利于新形成的和已有的优良单倍型的保留,是鲢鳙养殖性能退化的原因之一.     

遗传全雄尼罗罗非鱼与吉富罗非鱼养殖性能比较

以超雄鱼为父本进行遗传全雄鱼的繁育是获得全雄罗非鱼苗种的方法之一.为了评估全雄尼罗罗非鱼的养殖性能,进行了遗传全雄尼罗罗非鱼与吉富罗非鱼的池塘及网箱养殖比较试验.结果显示,初始体长3～5 cm的遗传全雄尼罗罗非鱼和吉富罗非鱼鱼苗经过100 d池塘养殖后,平均体质量分别达到558.00 g和501.80 g,遗传全雄群体...