室内工厂化养殖犬齿牙鲆的生长特性

对室内工厂化养殖的犬齿牙鲆生长特性进行了研究。结果表明,其生长旺盛期在2龄,日生长最快达5.52g/d,第1年平均为1.65g/d,第2年平均为2.34g/d,第3年平均为1.3g/d,第4年平均为0.75g/d。养殖1周年其平均体重可达600g左右,两周年达1500g;其全长和体重的关系为W=0.0076TL3.1785(R2=0.9765),全长与体高和标准体长的关系分别为TL=2.5685BD-0.6594(R2=0.9823),TL=1.1957SL-0.1724(R2=0.9922)     

Thermal Optima for the Culture of Juvenile Summer Flounder,Paralichthys dentatus

Abstract

Summer flounder, Paralichthys dentatus, aquaculture has shown promise over the recent past and a considerable body of knowledge is amassing for this species of flatfish. Even with the amassing data, basic information on environmental parameter ranges to maintain in indoor culture systems is still lacking. Therefore, the current study was undertaken to elucidate a temperature range that may be best suited for juvenile summer flounder production in indoor recirculating aquaculture. A 10-week study was designed to address 19, 24 and 29°C as potential temperatures for the culture of summer flounder. Fish averaging 9.5 g initial weight were stocked into triplicate 20-L aquaria per treatment after conditioning to their respective temperatures for 1 week. Fish were fed to apparent satiation twice daily a 50% crude protein fingerling diet and weighed every 2 weeks to assess growth rates.

Juvenile summer flounder grew better at 24 and 29°C (167 and 197% increase initial weight, respectively) than at 19°C (97% increase in initial weight) with increased individual fish variation within a treatment as temperature increased above 19°C. Feed efficiency was greatest at 24 and 29°C (0.65 and 0.57, respectively), but survival decreased at temperatures above 19°C (93, 60 and 57% for 19, 24 and 29°C, respectively). There was no effect of temperature on the hepatosomatic index or interior muscle ratio, but the finray muscle ratio was slightly elevated when flounder were cultured at 29°C. The lipid content of the finray muscle and liver also increased at 29°C. Therefore, 24°C appears to be the best culture temperature for summer flounder with respect to growth rates and efficiency, but survival and homogeneity of flounder may be lowered at temperatures above 19°C.     

异源精子诱导犬齿牙鲆的雌核发育

用冷冻保存的花鲈精子作为异源精子,采用紫外线(UV)对精子进行照射使其遗传物质失活,然后与卵子进行"授精",可以刺激犬齿牙鲆鱼卵进行雌核发育,在受精后一定时间采用冷休克处理"授精"卵,抑制第二极体排出成功获得了犬齿牙鲆雌核发育二倍体鱼苗.实验表明:犬齿牙鲆同源精子经80 mJ/cm2的紫外线照射可以完全失活,冻存花鲈精子经紫外线照射后也同样具有诱导犬齿牙鲆雌核发育的能力.无论同源精子还是异源精子,最佳诱导条件为在18℃条件下,精子经80 mJ/cm2的紫外线照射,受精后4～5 min将受精卵放在3℃海水中进行冷休克处理,持续时间为45 min,同源精子和异源精子二倍体诱导分别为32.66%±7.03%和28.00%±6.48%.采用形态学、流式细胞仪DNA含量分析和微卫星标记技术对雌核发育鱼苗进行了分析,证明了雌核发育鱼苗为雌核发育二倍体.     

Arachidonic acid requirements in larval summer flounder, Paralichthys dentatus

The arachidonic acid (20:4n-6,AA) requirements of larval summer flounder weredetermined for the rotifer- and Artemia-feeding stages. Experimental emulsionscontained adequate n-3 highly unsaturated fattyacid (HUFA) ratios and emulsion levels of AAwere set at 0, 3, 6, 9, and 12% (AA0, AA3,AA6, AA9, and AA12). Examination of fatty acidlevels in live feeds and larval tissuesconfirmed the physiological incorporation offatty acids relative to dietary levels. In thefirst experiment, survival, growth, andsalinity tolerance (2-h in 70) were measuredat 18 days after hatch (dah) after feeding thelarvae the various levels of AA. Larvae fedAA6-enriched rotifers were better able tosurvive the salinity tolerance test. AAenrichment up to 12% had no effect on growthand survival. In the second experiment, larvaewere fed AA0- or AA6-enriched rotifers until 23dah, followed by unenriched 24- and 48-h Artemia nauplii until 32 dah. These larvaethen were subdivided and fed AA-enriched Artemia from 33-45 dah. At the end of thisexperiment, larvae fed AA6-enriched rotifershad higher survival, increased growth, andsurvived better in the salinity tolerance test(2-h in 80). The enrichment of Artemiadid not have any effect on these variables.Thus, the provision of AA6-enriched rotifers(10 mg AA g^–1 DW) early in larvaldevelopment may serve to enhance larval stresstolerance at the rotifer stage while alsoincreasing larval survival, growth, and stresstolerance later in the Artemia stage.     

Cryopreservation of summer flounder,Paralichthys dentatus L., sperm

The summer flounder, Paralichthys dentatus L., is a high‐value species and considerable research has been conducted to determine practices conducive for its culture. As milt can be limited in this species, experiments were conducted to develop a practical sperm cryopreservation protocol for hatchery use. Two dilution ratios (1:2 and 1:4; sperm:extender), 2 diluents (saline and sucrose‐based), 2 cryoprotectants (10% DMSO and 12% glycerol) and 3 freezing rates (?5, ?10 and ?15°C min^?1) were evaluated using differential staining to assess post‐thaw sperm survival. Seven combinations of the factors examined reduced post‐thaw viability by less than 30%. The average viability of sperm from fresh, pooled flounder milt (67.2 ± 2.9%) was not different from that of thawed milt diluted 1:4 with sucrose diluent (10% DMSO) frozen at ?5°C min^?1 (38.4 ± 7.7%) and fertilization and hatch success were not different in trials using fresh or thawed, cryopreserved sperm. From these experiments a practical sperm cryopreservation method was developed, but further refinement of the freezing protocol is necessary to optimize results.     

Metamorphosis in summer flounder: manipulation of rearing salinity to synchronize settling behavior, growth and development

In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and settling behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to size grading. Our goal was to use an environmental salinity change as a cue to synchronize settling behavior and produce a larger, more uniformly sized cohort of juvenile summer flounder. Early metamorphic flounder were exposed to either a 5-day fluctuating (30–20–30–20–30 ppt; “Flux”) or a single (30–20 ppt; “20 ppt”) drop in rearing salinity. A control (continuous 30 ppt) was used for comparison. Average values for a peak settlement interval (PSI; defined as the interval beginning on the day by which the first 20% had settled until the day 80% had settled) were not affected by salinity manipulation, though the 20-ppt treatment did significantly increase percent settled per day by 54 dah. Average fish size was increased by the 20-ppt treatment (19.3±0.5 mm), but not the flux treatment (17.2±0.4 mm), compared to the control (17.6±0.5 mm). Developmental stage was significantly increased in the 20-ppt treatment (3.2±0.1) in comparison to the Flux (2.9±0.1), but not the control (3.1±0.1). However, the 20-ppt treatment reduced variance in development. To confirm the positive effects of the 20-ppt treatment, a second experiment was performed. A single salinity drop (“20 ppt”), a previously successful ([Gavlik, S., Albino, M., Specker, J.L., 2002. Metamorphosis in summer flounder: Manipulation of thyoid status to synchronize settling behavior, growth, and development. Aquaculture 203 (3-4), 359-373]thyroid hormone manipulation treatment (“TH”) and a combination of the two (“TH+20 ppt”) were compared to a control (continuous 30 ppt, no thyroid manipulation). The mean PSI was significantly reduced by both TH (7±1 days) and TH+20 ppt (8±0 days) treatments, compared to the control (11±1 days). The PSI for the 20-ppt treatment (9±0 days) was not significantly different than the control. The percent flounder settled per day was significantly increased by 20 ppt salinity and significantly modified (decreased, then increased) by TH manipulation. Flounder exposed to 20-ppt salinity were both larger (20 ppt: 18.6±0.3 mm; TH+20 ppt: 18.3±0.3 mm) and more developmentally advanced (20 ppt: 3.1±0.04; TH+20 ppt: 3.2±0.03) than flounder in 30 ppt (TH: 17.8±0.3 mm/3.1±0.3; Control: 17.9±0.3 mm/3.0±0.05). Finally, 20-ppt treatment reduced variance in development, while TH treatment reduced variance in both growth and development. Percent survival was unaffected by treatment in both experiments. In summary, a decrease in rearing salinity, from 30 to 20 ppt, increased growth, settling behavior and development of metamorphosing summer flounder. A decrease in rearing salinity, in combination with a TH manipulation, should result in larger, more uniformly sized flounder cohorts. We expect this synchronization will reduce the cannibalism and labor costs associated with size grading of cultured, metamorphosing summer flounder.     

大西洋牙鲆雄鱼与漠斑牙鲆雌鱼杂交的初步研究

从山东引进全长3-5cm的美国大西洋牙鲆和漠斑牙鲆幼鱼到宁德市飞鸾镇海鑫育苗场,经2年6个月养殖后,从养殖群体中挑选出大西洋牙鲆雄鱼为父本,漠斑牙鲆雌鱼2为母本,在生殖季节通过埋植激素和人工调控环境条件催熟亲鱼,采用人工受精方法,获得杂交受精卵478．6g,受精率为62．9％,孵化率为75．3％,获得初孵仔鱼36万尾。经过65d的培育,育出平均全长4．20cm的杂交鱼苗22万尾,育苗成活率61．1％。鱼苗生长迅速,初步表现出杂交子代的优势性状。     

夏牙鲆引进与室内池养成试验

2002年11月从美国引进夏牙鲆(Paralichthys dentatus)鱼苗2000尾,平均体长8．3 cm,平均体宽3．6 cm,平均体重8．26g,在室内长方形育苗池内试养,水温9-32℃,盐度20-28,通过投喂自制的湿颗粒饲料,控制水质,防治病害等措施,经过1年试养,夏牙鲆平均体长36．80 cm,体宽15．77 cm,体重达750 g。本试验为室内池养殖夏牙鲆提供了有实用价值的技术资料。     

大西洋牙鲆的生物学特性

大西洋牙鲆 (Atlanticflounder) ,主要分布于北美洲大西洋沿岸 ,是西北大西洋所产四种牙鲆中的一种较大型鱼类。为了改变我国牙鲆鱼种单一的局面 ,我们首次于 2 0 0 2年 9月 1 2日从美国GreatBayAquaculture,LLC .引进犬齿牙鲆鱼苗5 0 0 0尾试养 ,养殖 1 2个月平均体重达 5 93g     

褐牙鲆♀×大西洋牙鲆♂杂交育种研究

为探讨褐牙鲆和大西洋牙鲆杂交育种的可行性,通过繁殖调控使褐牙鲆和大西洋牙鲆同步性成熟,采取正反交试验,获得了褐牙鲆(♀)×大西洋牙鲆(♂)杂交F1代——花美牙鲆(Paralichthys olivaceus♀×P.dentatus♂)。花美牙鲆受精卵卵径平均1.01mm;孵化适宜温度15～21℃,盐度25～35,孵化率平均71.3%,初孵仔鱼全长2.5～2.7mm;仔鱼在16～20℃下36d后伏底变态,变态个体全长平均11mm,育成率32.5%;反交受精率和孵化率极低,未获得杂交后代。简述了其发育时序和形态特征,探讨温度、盐度对花美牙鲆胚胎和仔鱼发育的影响,比较亲本与杂交鱼早期生长特征,初步分析反交不成功的原因。     

褐牙鲆♀×大西洋牙鲆♂杂交育种研究

为探讨褐牙鲆和大西洋牙鲆杂交育种的可行性，通过繁殖调控使褐牙鲆和大西洋牙鲆同步性成熟，采取正反交试验，获得了褐牙鲆（♀）×大西洋牙鲆（♂）杂交F1代——花关牙鲆（Paralichthysolivaceus早×Pdentatus6）。花关牙鲆受精卵卵径平均1．01mm；孵化适宜温度15—21℃，盐度25～35，孵化率平均71．3％，初孵仔鱼全长2．5～2．7mm；仔鱼在16—20℃下36d后伏底变态，变态个体全长平均11mm，育成率32．5％；反交受精率和孵化率极低，未获得杂交后代。简述了其发育时序和形态特征，探讨温度、盐度对花关牙鲆胚胎和仔鱼发育的影响，比较亲本与杂交鱼早期生长特征，初步分析反交不成功的原因。     

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.     

舟山褐牙鲆（Paralichthys olivaceus）仔鱼摄食和生长的研究

试验研究了褐牙鲆Paralichthys olivaceus仔鱼的摄食和生长。结果表明,仔鱼初次开口摄食时间在6日龄（16～18℃）,初次摄食率为30％,8日龄饥饿仔鱼最大初次摄食率为65％,孵出后第9天达到不可逆点（PNR）,混合营养期为3d左右。初次摄食强度和初次摄食率开始时较低,在卵黄囊耗尽时达最高,然后下降。随着饥饿时间的延长,仔鱼出现“负增长”,孵化第11天存活率仅为10％,12日龄全部死亡。     

赤潮异弯藻对牙鲆早期发育的影响

就赤潮异弯藻(Heterosigma akashiwo)藻液及各组分对牙鲆(Paralichthys olivaceus)早期发育阶段的影响及敏感性时期作了探讨。实验结果表明，原肠期前的发育卵和初孵仔鱼对赤潮异弯藻较其他发育阶段更为敏感。在同等条件下藻液对牙鲆早期发育各阶段的毒性最大，其次是藻细胞碎片和藻细胞内容物，去藻过滤液的毒性最小。暴露在高浓度80000cells／ml藻液中，96h后仔鱼的存活率为47．6％；而在同浓度的去藻过滤液中，96h后仔鱼的存活率为90％。藻液对牙鲆仔鱼96h LC50为35042cells／ml。     

Sex differentiation of summer flounder (Paralichthys dentates L.) raised at practical hatchery temperatures

Female summer flounder grow considerably faster than males, and rearing temperature has been shown to influence sex differentiation in related species. The present studies were conducted to examine sex differentiation of post‐metamorphic juveniles reared at temperatures conducive for commercial production. In experiments 1 and 2, offspring produced from crosses with meiogynogenetic, sex‐reversed males and normal females were raised at 14, 16 or 18°C for ≥300 days or 12°C for 30, 60 or 120 days and then transferred to a male‐determining temperature (21°C). In all cases, the fish developed predominantly as phenotypic males (≥74%). In a third experiment, offspring produced from crosses with normal males and females were reared at 15, 17 and 19°C for 111, 227 and 278 days and then transferred to 21°C. Most fish (≥92.1%) developed as phenotypic males irrespective of rearing temperature or length of exposure. Several hypotheses are proposed for these findings and further research is necessary to understand the sex‐determining mechanisms in this species before the economic advantages associated with sexually dimorphic growth can be realized.     

牙鲆养殖群体遗传变异的微卫星标记研究

应用10对微卫星引物对中国牙鲆一个养殖群体的30个个体进行了群体遗传结构分析。结果显示，微卫星标记比其他标记具有更高的多态性，10个微卫星座位的等位基因数在4～10之间，有效等位基因数在2．23～5．82之间，平均等位基因数为7．6，群体平均杂合度为0．6960，Hardy-weinberg遗传偏离指数的平均值为0．1774。     

Cytological studies on induced meiogynogenesis in Japanese flounder Paralichthys olivaceus (Temminck et Schlegel)

The cytological process of induced gynogenetic development and subsequent chromosome duplication by a cold shock treatment was observed in Japanese flounder Paralichthys olivaceus (Temminck et Schlegel). Mature eggs were at the metaphase of the second meiosis when inseminated with ultraviolet (UV)-irradiated sperm of red sea bream Pagrus major . After the beginning of cold shock treatment, the previously visible spindle became invisible, probably due to the side effect caused by cold shock treatment. The chromosomes at the centre of the metaphase plate were condensed. This condition continued during the duration of the cold shock treatment and several minutes after it. The release of the second polar body was blocked and it developed into a female-like pronucleus. Then, it fused with the female pronucleus to generate a diploid zygotic nucleus, and the egg exhibited the first mitosis. Consequently, the haploid female chromosome set of the egg was doubled by the inhibition of the second polar body release. There was a significant delay in developmental time in the gynogenetic eggs when compared with that in the normal eggs. From the time of insemination to early cleavage, the UV-irradiated heterospecific sperm nucleus remained condensed.     

Survival of larval summer flounder Paralichthys dentatus on formulated diets and failure of thyroid hormone treatment to improve performance

Summer flounder is a new aquaculture species, the culture of which could be made simpler by the replacement, to the greatest extent possible, of live feed with formulated diets. Previous work has shown that development of the summer flounder stomach can be accelerated by treatment of the larvae with thyroid hormone. Two series of experiments were conducted. In the first experiment, 2-week feeding trials were conducted beginning with fish (which were not treated with thyroid hormone) 14, 21, 28, 35, or 42 days after hatch (DAH) to determine when they could begin to utilize commercially available formulated diets. In the second experiment, two groups of sibling larvae, one treated with thyroid hormone, the other not, were placed in similar 2-week feeding trials at 25, 30 or 35 DAH to test whether survival of thyroid hormone-treated larvae would surpass those of untreated larvae. The first series of experiments demonstrated that the larvae could not effectively utilize the formulated diets until 35 DAH. The second series of experiments indicated that thyroid hormone-treated larvae do not exhibit significantly greater survival than untreated larvae.     

Dietary choline requirement of juvenile olive flounder (Paralichthys olivaceus)

An eight‐week study was conducted to determine the optimum dietary choline level in juvenile olive flounder, Paralichthys olivaceus. Seven diets were prepared to contain 0, 250, 500, 750, 1,000, 2,000 and 3,000 mg/kg diet. Juveniles (5.9 ± 0.03 g; 5.5 ± 0.4 cm; mean ± SD) were randomly distributed into 21 tanks (25 fish/tank) and fed one of the diets in triplicates. Survival rate of fish fed the diet containing the lowest choline level was significantly lower than those of fish fed the other diets (p < 0.05). Final body weight, weight gain, specific growth rate, feed efficiency and protein efficiency ratio significantly increased with increasing choline levels up to 1,000 mg/kg diet. Whole‐body protein and lipid contents increased in accordance with choline levels up to 750 mg/kg diet, beyond which they plateaued. Liver and muscle lipid contents elevated with increasing choline levels up to 2,000 mg/kg diet. Plasma cholesterol esters, triglycerides, cholesterol and total lipids were significantly influenced by the graded choline levels; however, responses of those indices were not identical. Broken‐line analyses of weight gain and liver choline concentrations responding to the graded choline levels revealed that choline requirements of the juvenile flounder could be between 847 and 1,047 mg/kg diet.     

牙鲆体质量与形态性状的异速生长分析

为分析牙鲆（Paralichthys olivaceus）体质量与形态性状之间异速生长的遗传规律,通过人工受精的方法建立牙鲆19个全同胞家系,测量了牙鲆不同日龄的体质量和形态性状。采用逐步回归方法建立最优联合异速生长模型,将此模型镶嵌到体质量动物模型的每个遗传和环境效应中,进一步分析对多个形态性状异速生长遗传规律。静态异速生长分析表明：体质量与全长之间存在最大异速生长指数（1.415 5）,表现为正异速生长,剩余形态性状与体质量之间的异速生长指数为0.061 5~0.718 0,皆表现为负异速生长。全长与尾柄高之间异速生长指数的正遗传相关最大（0.907 8）;全长与尾柄长之间的负遗传相关最大（0.946 8）。不同模型通过统计标准比较,确定模型Ⅰ为进行牙鲆动态异速生长分析的最优随机回归模型。