中华鲟幼鲟维生素C营养需要的研究

本研究旨在确定中华鲟幼鲟对维生素C(VC)的营养需要量。配制含VC分别为0.5、59.8、119.5、239.1、478.1和956.2 mg/kg饲料的6组日粮(分别编号为C0.5、C59.8、C119.5、C239.1、C478.1和C956.2),连续投喂中华鲟幼鲟8周后,以生长速度、组织VC含量和部分相关酶活性来确定中华鲟对VC的需求量。结果表明,C0.5和C59.8组鲟鱼的增重率、饲料效率、蛋白质效率都低于C119.5组,进一步提高饲料VC含量,也没有显著变化(P>0.05);C478.1组的肝脏和肌肉组织VC含量达最高水平;C239.1组血清溶菌酶活性最高;C239.1组SOD活性最低。根据平均增重率和饲料效率做折线法分析表明,维持中华鲟最佳生长的饲料VC含量为108.5 mg/kg;肝脏中VC含量达最大时饲料VC添加量为309.4 mg/kg;肌肉中VC含量达最大时饲料VC添加量为273.3 mg/kg。     

温度对中华鲟精子、卵子短期保存的影响

研究了中华鲟精子和卵子在低温(8,12℃)、中温(16,20℃)和高温(24,28℃)条件下短期保存的效果。结果发现:精子保存时间随着保存温度的升高逐渐缩短,8℃下可保存146 h以上,而28℃下只能保存32 h。低温下保存精子的活力强于高温下保存的精子,表现为快速运动时间和总活动时间较长;卵子适合在中温(16,20℃)下保存,高温或者低温对卵子的保存都不利,28℃下只能保存4~8 h,8℃下只能保存4~10 h,而在16℃和20℃下可保存18~20 h。     

Effects of stocking density on haematological parameters,growth and fin erosion of great sturgeon (Huso huso) juveniles

The influence of stocking density (1, 2, 4, 6 and 8 kg m^?2) was investigated on haematological parameters, growth and fin erosion of great sturgeon (Huso huso) juveniles for a period of 8 weeks. The mean weight of fish at the start of trial was 93.13±1.04 g. After 8 weeks of rearing, the mean weight was 362.4, 319.7, 267, 242.1 and 211.1 in densities 1–8 kg m^?2 respectively. The results of this study showed that growth parameters, including condition factor, weight, weight gain, feed conversion ratio, specific growth rate and body weight increase, had a statistically significant difference among treatments (P<0.05). A significant difference (P<0.05) was observed in haematocrit, but the other haematological parameters, including red blood cells, white blood cells (WBC), haemoglobin concentration, mean corpuscular haemoglobin, mean corpuscular volume, mean corpuscular haemoglobin concentration and differential WBC count, showed no significant effect with stocking density (P>0.05). At the end of the experiment, stocking density had no significant effect on plasma cortisol and glucose concentration. The fin length (dorsal, anal, ventral, pectoral and caudal) of fish was measured to calculate the fin index. According to this index, dorsal, anal, ventral and pectoral fins showed no significant difference among treatments (P>0.05), but the erosion of the caudal fin was significantly different between fish held on 6 and 8 kg m^?2 (P<0.05). These results showed that rearing density has a major effect on the growth indices of H. huso. Unlike many other fish, great sturgeon exhibited lower stress responses to high stocking density. This indicates that they are more tolerable to rearing conditions in high stocking densities. With respect to the various effects that density causes on growth, fin erosion and physiological and haematological parameters, better understanding of these phenomena considering different levels of density could have a beneficial impact on many rearing steps of this species.     

Diet composition of sturgeon fry (Acipenser persicus) reared in fertilized earthen ponds

Artificial rearing of fry has been introduced as an alternative to supply fry and juvenile sturgeon in order to restock the depleted sturgeon population in the Caspian Sea. The aim of this study is to assess the feed selection characteristics of sturgeon (Acipenser persicus) fry during the period in which they stay in earthen ponds before being released into the river. Sturgeon fry weighing around 150 mg were introduced into five almost similar‐sized earthen ponds. The ponds were enriched with fertilizer to supply natural food for the fries. A weekly sample of six specimens was collected from each pond during the 5 weeks of the experiment. All collected fish were weighed and then dissected for inspection of the stomach and the intestine content. The overall stomach content measured from 150 fish showed that around 74% of the stomach content was composed of chironomids and the rest was daphnia and cyclops. At the beginning of the study (first 2 weeks), sturgeon fry feed more on daphnia and cyclops; this trend, however, reversed in the last 2 weeks of the study. In conclusion, sturgeon fry feed on three prey groups—chironomids, daphnia and cyclops—during their lifespan in earthen pond. Feeding on chironomids larvae increased with sturgeon fry size.     

水流对杂交鲟幼鱼游泳行为的影响

在26℃水温下,使用特制的鱼类游泳行为测定装置研究了杂交鲟(Huso duricusGeorgi♂×Acipenser schrenc-kiBrandt♀)幼鱼在0 m/s、0.1 m/s、0.3 m/s、0.5 m/s 4种流速条件下的游泳行为。结果显示:杂交鲟幼鱼随着流速的增加趋流率增大,且在90min内趋流率达到100%所需的时间明显缩短。实过过程中0.3 m/s和0.5 m/s两组摆尾频率都高于0.1 m/s和静水组,但在各个时段内,摆尾频率与趋流率均没有显著的相关。杂交鲟幼鱼的游泳状态明显受到所处流速的影响:0.1 m/s流速下以逆流前进为主,约占时间比例56.3%;0.3 m/s流速下以逆流静止为主,约占时间比例58.1%;0.5 m/s流速下以逆流后退为主,约占时间比例80.7%。在逆流前进和逆流静止两种游泳状态下,杂交鲟幼鱼的游泳速度和摆尾频率呈线性相关。但在逆流后退和顺流而下两种状态下,两者之间却没有显著的相关,且此两种状态下其游泳速度和摆尾频率随流速增加的变化趋势也不一致。     

鲟鱼鱼苗的食性转换技术

对鲟鱼食性转换的时间、转食前的分养技术、转换方法、转换成活率进行了概述,分析了食性转换过程中影响转食成活率的因素,以期为鲟鱼苗养殖过程中进行转食驯化提供参考.     

Mortality and recovery of runt white sturgeon (Acipenser transmontanus) in a commercial farm in California, USA

We investigated the effect of raising runt white sturgeon (Acipenser transmontanus) separately from dominant fish during the initial stages of grow-out in a commercial farm. Runt fish are poor-growers, have underdeveloped muscle mass, swim slowly and are more-frequently found at the top of the water column. The objective of the study was to describe the mortality and recovery rates (and their determinants) of white-sturgeon runts after separating them from dominant fish. Runt white sturgeon were stocked into twelve 2 m × 2 m rectangular tanks and graded periodically during a follow-up of 46–102 days. Overall mortality rates ranged from 0.3 to 7 dead fish per 1000 sturgeon-days at risk and overall recovery rates from 3.9 to 13.5 recovered fish per 1000 sturgeon-days at risk. Period-specific mortality and recovery rates increased over time. The period-specific mortality rates for all three periods were significantly higher for tanks of runts originating from grow-out tanks with high mortality (p-values: first period = 0.06; second period = 0.09; third period = 0.03), but were similar for tanks of runts of high- and low-mean initial weight. The period-specific recovery rates were significantly higher in runts originating from high-mortality grow-out tanks only for the third period (p = 0.05) but not the first and second periods (p-values = 0.33 and 0.25, respectively). Recovery rates were significantly higher in the higher-mean-weight runts tanks for the first and third period but not for the second (p-values: first period = 0.02; second period = 0.65; third period = 0.06). We concluded that the proportion of runts that recover during a 46–89 day period is substantial (16–58%); therefore, it might be worthwhile growing such fish separately in a fish farm for about three months. Financial analysis showed that this practice was profitable, if the value of white sturgeon fish for the farm exceeded $2.05 per kg.     

葛洲坝大江泄流对中华鲟产卵场空间分布特征的影响

葛洲坝的修建阻隔了中华鲟上溯到上游产卵场的洄游通道,使其被迫在葛洲坝坝下4 km范围内形成新的产卵场,葛洲坝泄流对中华鲟产卵场的空间分布造成了一定影响.为了探明葛洲坝小出库流量且仅开启大江电厂发电泄流状况下,大江电厂发电泄流量的改变对坝下中华鲟产卵场产卵栖息适合度以及产卵场空间分布特性的影响,在构建中华鲟产卵场三维水动力数学模型及栖息地评价模型的基础上,对葛洲坝大江不同发电泄流量及不同机组泄流量工况下中华鲟产卵栖息地空间分布特征进行深入分析.结果表明,大江电厂单机泄流量增量小于200m^3/s时,可增加坝下中华鲟产卵栖息地适宜值,有利于中华鲟产卵繁殖;增加大江各机组的发电泄流量对坝下中华鲟产卵场空间分布具有一定的影响,各机组流量增量小于200m^3/s时,中华鲟产卵场面积增大,产卵场位置自右岸向左岸扩展,中华鲟获得更为广阔的产卵空间.     

鲟鱼消化生理和营养需求研究进展

鲟鱼是一类古老的鱼类,其消化系统具有较为原始的特征,其消化生理也有特异性。鲟鱼消化酶的种类组成与活性及其在发育过程中的变化模式与食性密切相关。鲟鱼属于偏肉食性鱼类,对饲料蛋白质的需求量较高。鲟鱼对脂肪和糖类的消化能力较强,能够利用高水平的脂肪和糖类。     

盐度驯化下施氏鲟的血液生化指标

测定了5个不同盐度（0、10、20、25、28）下分别养殖20d的施氏鲟（Amursturgeon，Acipenser schrenckii）的血液生化指标。结果表明：总蛋白（TP）含量随盐度的升高先上升后下降，总胆红素（T—BIL）随盐度的升高逐渐增加，甘油三脂（TRIG）的变化趋势与总蛋白TP基本一致，总胆固醇（CHO—L）随盐度的升高变化不明显，高密度脂蛋白（HDL—C）随盐度的升高先缓慢下降后略有上升。血糖（G）随盐度的升高先缓慢下降后逐渐上升。肌酐（CREA）的含量随盐度的升高先上升后下降，尿素氮（BUN）随盐度的升高先上升后下降。随盐度的升高，碱性磷酸酶（ALP）逐渐下降，血清淀粉酶（AMY）先下降后上升，谷草转氨酶（AST）和谷丙转氨酶（ALT）先上升后下降再上升。Na^＋浓度先上升后下降最后基本保持稳定，Cl^-浓度、P含量和Na^＋浓度变化趋势基本一致，K^＋浓度先上升后下降，Ca^2＋浓度则无显著性变化。从驯化后血液生化指标分析，施氏鲟具有较强的渗透调节能力，经过驯化可以在盐度28的海水中生活。