体重和温度对草鱼摄食小浮萍的影响

研究草鱼(Ctenopharyngodon idella)对浮萍的摄食能力及主要影响因素,为合理利用草鱼控制小江回水区浮萍暴发提供依据。草鱼(体重29.7~491.2 g)取自红安县中海农业科技有限公司渔场,小浮萍种源采自重庆市云阳县高阳镇黄莲坝库湾。在试验室条件下研究了草鱼对小浮萍的最大摄食量、最大摄食率与体重和温度的关系。结果表明,在水温(25.82±0.57)℃条件下,随着体重的增加(40.36~478.17 g),草鱼的最大摄食量增大,但最大摄食率呈减小的趋势,两者与体重的相关关系分别为C_(max)=2.460W~(0.779),FR_(max)=246.0W~(-0.221);水温(16.55~30.50℃)对草鱼的最大摄食量和最大摄食率的影响极显著(P0.01),最大摄食量和最大摄食率与水温的回归方程分别为C_(max)=0.074T~(2.045),FR_(max)=0.164T~(1.940);建立的预测不同温度和体重条件下草鱼对小浮萍最大摄食率的模型为:FR_(max)=0.410T~(1.940)W~(-0.221)。     

环境与摄食对山东省近海鱼礁区不同体长许氏平鲉分布的影响

为研究环境与摄食因素对人工鱼礁区不同体长许氏平鲉分布的影响,采用2017—2018年山东省近岸3处鱼礁区环境和渔业资源的调查数据,利用变异系数CV均值将样本的体长分为10组,每组体长间隔为33 mm,并使用Bray-Curtis相似性指数比较不同海域许氏平鲉体长组成的相似性;运用去趋势对应分析(DCA)、典范对应分析(CCA)分析各环境要素对不同体长组许氏平鲉分布的影响;运用胃含物分析法分析许氏平鲉的食物组成。结果显示,西霞口与长岛鱼礁区样本体长组成相似性指数为70.66%,前三岛鱼礁区与西霞口鱼礁区、长岛鱼礁区的相似性指数较低,分别为54.94%和59.46%;大体长(299～365mm)许氏平鲉的分布与水深、水质指数(WQI)和化学需氧量(COD)相关性较大,喜好水深较深、营养丰富的水域;小体长(35～200 mm)许氏平鲉喜好水深较浅,水质好的水域。大体长(200～365 mm),高龄(2～3龄)的个体主要摄食鱼类、虾类和蟹类,优势饵料为鱼类(IRI为65.94%);小体长(35～200 mm),低龄(0～1龄)的个体主要摄食虾类和蟹类,优势饵料为虾类(IRI为45.69%)。研究表明,在浅水区域投放幼鱼保护型鱼礁,为幼鱼提供庇护所;将捕捞作业集中在深水区,减少对许氏平鲉小体长个体的兼捕,可以达到针对性增殖、保护许氏平鲉资源的目的。     

Comparative study on dietary protein requirements for juvenile and pre‐adult gibel carp (Carassius auratus gibelio var. CAS III)

Two 8‐week growth trials were conducted in indoor recirculation system to evaluate the protein requirements for juvenile (3.70 ± 0.20 g) and pre‐adult (85.2 ± 0.70 g) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets were formulated for each trial using fish meal and casein as protein sources, and protein level was 250–450 g kg^?1 in Trial 1 and 200–450 g kg^?1 in Trial 2. With the increasing dietary protein, feeding rate (FR) and feed conversion ratio (FCR) significantly decreased (P < 0.05). Weight gain (WG) increased first and then reached a plateau in 330–450 g kg^?1 in Trial 1 (P > 0.05), while decreased after the maximum value in 350 g kg^?1 in Trial 2 (P < 0.05). Productive protein values (PPVs) were lower in 370–450 g kg^?1 in Trial 1 and 400–450 g kg^?1 in Trial 2 (P < 0.05). Increasing dietary protein level increased protein content and decreased lipid content in whole fish body and white muscle (P < 0.05). Apparent digestibility coefficient of dry matters (ADC_d) decreased, while apparent digestibility coefficient of protein (ADC_p) increased in 370–450 g kg^?1 in Trial 1 and 250–450 g kg^?1 in Trial 2 (P < 0.05). Trypsin activity significantly increased in 370–450 g kg^?1 in Trial 1 (P < 0.05) and was not affected in Trial 2 (P > 0.05). Hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in both trials increased when dietary protein was above 400 g kg^?1 (P < 0.05). Based on quadratic regression of WG, it was estimated that dietary protein requirement for maximum growth was 414 g kg^?1 (digestible protein of 376 g kg^?1) and 365 g kg^?1 (digestible protein of 324 g kg^?1) for juvenile (3.70 g) and pre‐adult gibel carp (85.2 g).     

Off-Season Spawning of Eurasian Perch Perca Fluviatilis

This study was designed to determine the effects of the selection for body weight and of two final warming durations during an out-of-season reproductive cycle on gonad recrudescence, plasma steroid levels and spawning in Eurasian perch Perca fluviatilis males and females. Two different bodyweight classes (200–250 and 350–400 g) and two different warming periods (1 or 2 months) were studied.At the end of the chilling period, a significant effect of the selection for body weight was observed on gonad development whereas fish were the same age. According to higher levels in testosterone (12 ng mL^–1), a better development was recorded for smaller breeders (P < 0.05). A short water warming period up to 14°C (1 month v.s. 2 months) allowed higher rates of females with completed gonadogenesis (33–38% v.s. 7–8%) and spawning (31–33% v.s. 0%) (P < 0.05). Spontaneous out-of-season spawning (17 ribbons) and larvae were obtained. Relative fecundity was about 100 eggs g^–1 of female body weight. Five ribbons were partly fertilized with a rate ranging from 5 to 90%. These studies have shown that delayed spawning in Eurasian perch can be obtained by a temperature manipulation, but results are not sufficient because of low stimulation rate of females, low spawning rates and high heteroge-neity of fertilization rates. The effects of other environmental factors like photoperiod should be tested in further experiment to improve the protocol inducing out-of-season spawning production.     

Effect of dietary phosphorus levels on growth and body composition of crucian carp,Carassius auratus under indoor and outdoor experiments

Indoor and outdoor experiments were carried out simultaneously to evaluate the effects of dietary phosphorus levels on growth performance and body composition of crucian carp. Monocalcium was used to formulate extruded feed containing available phosphorus (AP) of 1.5 (D1), 4.7 (D2), 6.3 (D3) and 9.0 (D4) g kg^?1. Twelve 500‐L recirculating tanks were assigned to four triplicate groups with each tank stocked with 15 juveniles (39.88 ± 0.14 g) for indoor experiment. Twelve polyethylene enclosures were assigned to four groups with each one stocked with 120 juveniles (44.08 ± 1.36 g). After 8 weeks of feeding, survival ranged from 96% to 100%. Weight gain, special growth rate, protein efficiency ratio and feed conversion rate did not show significant differences among dietary treatments in both experiments. Fish cultured in the enclosures grew better, although D1 and D2 treatments did not reach significant level. Crude protein and phosphorus content of the fish were not significantly affected by dietary phosphorus level. Moisture, crude lipid, crude ash and vertebrae phosphorus were significantly affected by different phosphorus levels. Based on vertebrae phosphorus, crucian carp cultured in the tanks and in the enclosures showed phosphorus deficiency under 4.7 g kg^?1 and 6.3 g kg^?1 AP, respectively.     

不同健康程度和抗生素氟苯尼考干预下斑石鲷肠道菌群的结构差异

为了研究不同健康程度和抗生素氟苯尼考干预下斑石鲷肠道菌群结构的差异及其与养殖环境中菌群结构的相关性,采用Illumina Hi Seq PE250高通量测序的方法对健康、亚健康、典型黑身病和口服氟苯尼考条件下的斑石鲷肠道、养殖水体和颗粒饵料中的细菌多样性及群落结构进行了分析比较。结果显示,养殖水体中细菌多样性高于肠道和颗粒饵料。不同健康程度及氟苯尼考干预下斑石鲷肠道中细菌均以变形菌门、厚壁菌门和软壁菌门为主,且对应的操作分类单元(OTU)占样品全部OTU的比例均达到85%以上。黑身病的发生可影响斑石鲷肠道中丰度最高的前20种优势细菌种类的排名次序,其中变形菌门中的弧菌属的相对丰度显著增加,且随着弧菌属丰度的增加,斑石鲷的黑身病症状也逐渐加重。饵料中添加氟苯尼考投喂斑石鲷能使患病鱼肠道弧菌属的丰度从60.33%下降到1.29%,较大程度改变了肠道的菌群结构,并证实氟苯尼考有效防治黑身病。其次,养殖水体和颗粒饵料对斑石鲷肠道菌群也有一定影响,且养殖水体的影响高于颗粒饵料。本研究首次报道了斑石鲷肠道菌群结构,其研究结果为今后斑石鲷的健康养殖、疾病防控及其微生态学研究提供了参考依据和技术支撑。     

不同盐度下饵料蛋白质含量对凡纳滨对虾生长、体成份和肝胰腺组织结构的影响

设计了蛋白质含量为20.61%、30.52%、40.43%和50.34%的4种饵料(分别为CP20、CP30、CP40和CP50),研究饵料蛋白质含量对不同盐度下(分别为低盐度LS 2、中盐度MS 22和高盐度HS 32)凡纳滨对虾[(0.0144±0.0047)g]生长、成活及体成份的影响,测定了不同处理组对虾的肝胰腺指数(HIS)和肥满度(CF),试验为期8周.结果显示:(1)盐度对凡纳滨对虾的生长、成活、肥满度和灰分含量均有显著影响(P<0.05),而对肝体指数、体粗蛋白、体粗脂肪和水分无显著影响(P0.05),中盐度组对虾各指标均最高,其次为高盐度组,低盐度组最低;中、高盐度组对虾的增重率、特殊体重(长)增长率均显著高于低盐度组对虾(P<0.05),而中、高盐度组对虾的各生长指标无显著差异(P＜0.05);(2)饵料蛋白质含量对凡纳滨对虾的各生长指标和体粗蛋白含量影响显著(P<0.05),对其它各指标影响不显著(P<0.05).各盐度下,对虾生长和体粗蛋白含量均随饵料蛋白质含量升高而升高,投喂CP20的对虾组显著低于其它各处理组(P<0.05);肥满度和肝体指数均先随饵料蛋白质含量升高至40.43%而升高,然后稍有下降;饵料蛋白质含量对各盐度下对虾成活率影响均不显著(P0.05).(3)双因素方差分析结果显示,盐度和饵料蛋白质含量,除对体灰分含量存着着显著的交互作用外(P<0.05),对其它体生化成份含量、生长及体形态指标的交互作用均不显著(P0.05).(4)饲料蛋白质含量明显影响了凡纳滨对虾肝胰腺的组织结构,投喂CP30和CP40饵料的对虾肝小体基膜完整,投喂CP40对虾的肝小体中还出现了大量的存储细胞(R细胞);而投喂CP20饵料的对虾肝小体分布松散,R细胞数量较小,并且部分肝小体基膜破损;而投喂CP50饵料的对虾的肝小体排列紧密,且B细胞内出现大量内容物质.结果提示,提高饵料蛋白质含量虽然在一定程度上加快对虾的生长速度和增加肥满度,但是并不能提高低盐底下凡纳滨对虾的成活率.饲料中蛋白质含量的不适宜,尤其是含量过低,会导致对虾肝胰腺的结构发生变化甚至发生不同程度的病理变化.     

温度、盐度和体质量对钝缀锦蛤滤食率和同化率的影响

为探明钝缀锦蛤的摄食生理,以北海近海人工中间培育和养殖的钝缀锦蛤为试验材料,室内条件下采用试验生态法研究温度、盐度和体质量对钝缀锦蛤滤食率与同化率的影响。试验结果表明,在温度17～33℃条件下,滤食率随温度的升高,呈先升后降的趋势,滤食率(y)与水温(x)之间的回归方程为y=-4.338×10^-3 x^3+0.311x2-6.915x+49(r2=0.999),同化率随着温度的升高而增大,温度对同化率的影响显著(P<0.01);在盐度18～33条件下,滤食率随盐度的升高呈先增后降的趋势,盐度27～30时保持较高的滤食率,滤食率(y)与盐度(x)之间的回归方程为y=-0.027x^2+1.638x-19.52(r^2=0.994),同化率随盐度的升高而增大,盐度为30时同化率最高,盐度对同化率的影响显著(P<0.01);滤食率随体质量增加而降低,体质量对同化率影响不显著(P>0.05)。研究表明,钝缀锦蛤属典型热带和亚热带种群品种,适宜生活在温度和盐度较稳定的潮下带区域,非广温广盐性贝类。     

Compensatory growth and body composition of juvenile black rockfish <Emphasis Type="Italic">Sebastes schlegeli</Emphasis> following feed deprivation

ABSTRACT:   Compensatory growth, feeding rate, feed efficiency and chemical composition of juvenile black rockfish (mean weight 1.43 g) were investigated for 35 days after a 14-day feed deprivation treatment under four feeding conditions: one group continuously fed (control) and the other three groups fasted for 5 days (F5), 10 days (F10) and 14 days (F14). All fasted fish were re-fed from day 15. Only F5 achieved the same body weight as the control, indicating that complete compensation occurred in F5. The specific growth rate (SGR) of F5 was the highest at day 21 and then decreased thereafter, showing higher values than the control at days 21, 28 and 42. In contrast, although SGRs of F10 and F14 were higher than that of the control during the whole refeeding period except day 21, they did not catch up the control in body mass, indicating that only partial compensation occurred in F10 and F14. The feeding rate (FR) of all groups except F14 changed in a pattern similar to SGR (Spearman's rank correlation, r _s > 0.9), suggesting that SGR varied depending on FR. Similar feeding efficiencies (FEs) were found in the four groups and they did not vary significantly during the whole refeeding period, suggesting that FE was not the factor affecting SGR. At day 14, the ratios of lipid to lean body mass in F10 and F14 were lower than those in the control and F5, and there was no difference between the control and F5. At day 49, however, only F14 showed a lower value than the other three groups, and there was no difference among the three groups. These results indicate that juvenile black rockfish fasted for 5–14 days can exhibit compensatory growth after refeeding, but timing and degree vary depending on the duration of feed deprivation.     

虾夷扇贝体形性状对软体重和闭壳肌重的影响效果分析

利用虾夷扇贝表型性状资料,分析性状间的相关关系及其相关程度,建立相应的回归方程,为扇贝的选择育种奠定基础。试验随机抽取126只体形规则的3龄大连獐子岛海区底播增殖的虾夷扇贝,其中雌雄各63只,测定其壳长(X1)、壳高(X2)、壳宽(X3)、活体重(Y)、软体重(Z)和闭壳肌重(W),分别计算相关系数,采用通径分析方法计算了以体形性状为自变量对软体重和闭壳肌重作依变量的通径系数、决定系数及相关指数,定量的分析了体形性状对虾夷扇贝解剖性状的影响。结果表明虾夷扇贝壳长、壳宽、壳高与活体重、软体重和闭壳肌重的相关系数均达到极显著水平(P<0.01);壳高、壳宽是影响雌性软体重的主要因素,壳长、壳宽是影响雄性软体重的主要因素,而混合组受3个壳尺性状的共同影响;影响虾夷扇贝闭壳肌重的主要因素是壳宽,壳长、壳高的作用不显著;决定系数分析结果与通径分析结果有一致的变化趋势;多元回归分析,剔除不显著因子,建立了壳长、壳高、壳宽对软体重、闭壳肌重的回归方程：1). 雌性 Z= -128.573 +1.355X2 +1.407 X3;W= -8.216 +0.869X3;2). 雄性 Z =138.493+1.082 X1+2.524 X3;W= -11.855 + 0.955 X3;3). 混合 Z = -133.939 +0.606 X1+0.679X2 + 1.709X3;W= -9.525+ 0.896 X3。通过性状间的相关分析对两性状间的关系进行明确的定量,有利于制定合理的多性状选择方案,为虾夷扇贝选育提供理想的测度指标。