达氏鳇(♀)×西伯利亚鲟(♂)杂交幼鱼生长特性初步研究

对野生达氏鳇(Huso dauricus)(♀)与人工养殖西伯利亚鲟(Acipenser baerii)(♂)的杂交幼鱼在人工养殖条件下的生长进行研究。结果显示:在水温14.7~16.8℃的条件下,平均全长37.43 cm、平均体重178.9 g的达氏鳇杂交种幼鱼经过80 d培育后,平均全长和平均体重分别达到51.74 cm和533.1 g。其全长与日龄呈线性关系,关系式为L=0.1683t+10.942(R2=0.9665);体重与日龄呈指数函数关系,关系式为W=24.304e0.0129t(R2=0.9421);体重与全长呈幂函数关系,关系式为W=0.0007L3.4461(R2=0.9984),其中b大于3。结果表明:达氏鳇和西伯利亚鲟的杂交种幼鱼为异速生长类型,体重生长快于全长生长。     

Evaluation of lethal and non-lethal sampling methods for the detection of white sturgeon iridovirus infection in white sturgeon, Acipenser transmontanus (Richardson)

Pectoral fin tissue of white sturgeon was investigated as a potential non-lethal sample source for the detection of white sturgeon iridovirus (WSIV) infection. Histopathology and polymerase chain reaction (PCR) results using fin tissue were compared with the standard lethal histopathology sampling method that utilizes head tissue. Tissues for each of the three sampling methods were collected weekly for 8 weeks from individual sturgeon undergoing an experimental cohabitation challenge with fish infected with the Abernathy isolate of WSIV. Non-lethal fin histopathological evaluation did not reveal infection during the first 3 weeks of sampling, while non-lethal PCR and the lethal method were variable. However, all three sampling methods were equally capable of identifying infection from 4 to 8 weeks post-exposure. Of the survivors tested, all were negative by PCR and the lethal method, and only one fish was identified as being positive by non-lethal fin histopathology. In another experiment, all three sampling methods were applied to asymptomatic WSIV carriers in a case study conducted at the Kootenai Tribal Sturgeon Conservation Hatchery. Results showed that both lethal and non-lethal fin histopathology were equally effective in detecting infection, but PCR was unable to identify this strain of WSIV. Depending on the virus isolate, these results suggest that non-lethal sampling of fin tissue (histopathology or PCR) is comparable with the lethal sampling method at identifying WSIV infection once infection is established, and under certain circumstances may provide an alternative to lethal sampling.     

史氏鲟幼鲟对饲料中磷的需要量

通过生长饲养试验研究史氏鲟幼鲟对饲料中磷的需要量.以Ca(H2PO4)2·H2O为磷源,配制含磷水平分别为0.18%(对照组),0.40%,0.71%,0.98%,1.38%和1.66%的6组等能等氮纯化饲料,每组饲料饲喂3个重复,每个重复饲养20尾初体质量约为4.7 g的幼鲟.经过8周的饲养后,对生长、饲料效率、成活率、幼鲟肌肉常规组成及脊椎骨灰分和钙磷含量进行分析.结果表明,随饲料中磷含量的升高,鱼体增重率、饲料效率和特定生长率显著增加(P<0.05),直至0.98%组达最大,然后随着饲料磷含量的增加,这些指标显著降低(P<0.05);试验各添加组的成活率显著高于对照组(P<0.05),但各添加组间没有显著差异(P>0.05);饲料添加磷对鱼体肌肉水分、粗蛋白质和粗脂肪含量无显著影响(P>0.05);当饲料磷含量在0.71%～1.66%之间时,脊椎骨中灰分、钙和磷含量差异不显著(P>0.05),但显著高于对照组和0.40%试验组(P<0.05).经过折线回归分析得出,为维持史氏鲟幼鲟最佳生长和骨骼磷水平,饲料中磷的需要量为0.88%～1.00%(占干饲料).     

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。     

Comparison of growth performance and biometric relationships in two reciprocal sturgeon hybrids reared in net cages (Sicily, Mediterranean)

This study was designed to investigate growth performance in two sturgeon hybrids reared in two quadrangular floating cages moored in an artificial pond, representing the first experience of sturgeon culture performed at Southern Mediterranean latitudes. The research was carried out from December 2000 to July 2001 and tested the growth performance, feeding parameters and biometric relationships. The sturgeons were randomly collected from the cages on a monthly basis, and total length, standard length (SL) and wet weight (WW) were recorded. The specific daily growth rate (SGR_W) as somatic WW, food conversion ratio and condition factor (CF) were calculated. Biometric relationships, as linear regression, were also calculated on SL and WW data. Both hybrids grew slowly from December to April, but faster during the warm months. The growth performance of the two hybrids seems to be influenced by variability of the environmental conditions and, for both fish groups, there was a strong correlation between water temperature and SGR_W at temperatures below 25 °C. The CF (constantly below 1) was similar for both hybrids. The regression analysis for WW and SL calculated for the entire period showed a positive allometry for both hybrids, indicating that the fishes grew in weight at a greater rate than required to maintain constant body proportion.     

施氏鲟幼鱼的耗氧速率及窒息点

在两种不同温度下测定施氏鲟幼鱼的耗氧速率和窒息点，结果表明：施氏鲟幼鱼的耗氧速率随水中溶解氧增减而升降，其呼吸类型属顺应型，耗氧速率还随水温的升高而增大，随鱼体的增大而降低；在溶氧接近饱和值情况下，14℃水温时，平均体重7．8－26．9克鱼的耗氧速率为0．31－0．24mgO2/g/hr,窒息点1．35－1．32mgO2/L，水温25℃时，平均体重8．0－17．2克鱼的耗氧速率为0．61－0．53mg/O2/g/hr，窒息点为2．18－2．10mg/O2/L。     

A comparative study of some hematological features in young reared sturgeons (Acipenser persicus and Huso huso)

The physiological condition in fishes required for their selection as broodfish can be determined by hematological studies. The present study aims at examining the hematological indices in juvenile sturgeons at different stages of growth. The main blood features, such as total albumin content in blood, hemoglobin concentration and the erythrocyte and leukocyte count, were measured in a total of 54 specimens of 1-, 2- and 6-year old sturgeon (Persian sturgeon Acipenser persicus and beluga Huso huso), artificially produced at the Shahid Dr. Beheshti Fish Breeding and Rearing Center located in the Gilan Province.In the Persian sturgeon specimens studied, the total albumin concentration in the blood increased from 26.05 to 52.50 g l^–1, the hemoglobin concentration increased from 42.2 to 65.8 g l^–1, the erythrocyte count increased from 240 to 452.5 thousand cell ml^–1 and the leukocyte count increased from 13.43 to 46.48 thousand cells ml^–1. The total leukocyte was composed of 73.25 to 82.70% lymphocytes, 12.3 to 20% neutrophils, 2.25 to 6.50% eosinophils and 0.2 to 2.5% monocytes.In the beluga specimens studied, the total albumin concentration in the blood increased from 20.05 to 42.20 g l^–1, the hemoglobin concentration increased from 46.3 to 78.6 g l^–1, the erythrocyte count increased from 495 to 735 thousand cells ml^–1 and the leukocyte count increased from 31.6 to 57.7 thousand cells ml^–1. The total leukocyte was composed of 54.5 to 67.5% lymphocytes, 22.63 to 33.86% neutrophils, 6.60 to 13.7% eosinophils and 0.6 to 2.25% monocytes.This research reveals the trends of some hematological features during the growth and development of sturgeons in the South Caspian Sea, reared in artificial conditions. It shows that with the increase in age, the hematological indices also increased.