Risk factors for outbreaks of disease attributable to white sturgeon iridovirus and white sturgeon herpesvirus-2 at a commercial sturgeon farm

OBJECTIVE: To determine management, fish, and environmental risk factors for increased mortality and an increased proportion of runts for white sturgeon exposed to white sturgeon iridovirus (WSIV) and white sturgeon herpesvirus-2 (WSHV-2). ANIMALS: White sturgeon in 57 tanks at 1 farm and observations made for fish at another farm. PROCEDURE: A prospective cohort study was conducted. Data on mortality, proportion of runts, and potential risk factors were collected. Five fish from each tank were examined for WSIV and WSHV-2 via inoculation of susceptible cell lines and microscopic examination of stained tissue sections. An ANCOVA was used to evaluate effects of risk factors on mortality and proportion of runts. RESULTS: Major determinants of number of dead fish (natural logarithm [In]-transformed) were spawn, source (90% confidence interval [CI] for regression coefficient, 0.62 to 2.21), and stocking density (90% CI, 0.003 to 0.03). Main predictors of proportion of runts (In-transformed) were spawn, mortality incidence density (90% CI, 0.004 to 0.03), age (90% CI, -0.012 to -0.004), and the difference in weight between the largest and smallest nonrunt fish (90% CI, 0.0002 to 1.24). Additional observations indicated a possible protective effect attributable to previous exposure to the viruses. CONCLUSIONS AND CLINICAL RELEVANCE: Mortality and proportion of runts for white sturgeon after exposure to WSIV and WSHV-2 may be reduced for a farm at which the viruses are endemic by selection of specific broodstock, stocking with fish that survived outbreaks of viral disease, using all-in, all-out production, and decreasing stocking densities.     

Blood chemistry values for shovelnose and lake sturgeon

Blood chemistry panels are commonly used for assessing the general health of vertebrate animals. Here, we present novel blood chemistry data for two North American sturgeon species, shovelnose sturgeon Scaphirhynchus platorynchus and lake sturgeon Acipenser fulvescens. Measurements were done using a portable chemistry analyzer (VetScan Analyzer; Abaxis). Among the plasma values measured (mean ± SD for shovelnose and lake sturgeon, respectively) were total proteins (3.7 ± 0.9 and 2.8 ± 0.4 g/dL), albumin (2.0 ± 0.5 and 1.1 ± 0.2 g/dL), globulin (1.7 ± 0.7 and 1.7 ± 0.3 g/dL), glucose (107 ± 46 and 62 ± 9.7 mg/dL), sodium (Na(+); 132 ± 3.6 and 150 ± 14 mEq/L), potassium (K(+); 3.5 ± 0.2 and 2.8 ± 1.7 mEq/L), phosphorus (10.4 ± 1.9 and 11.6 ± 3.6 mg/dL), and aspartate aminotransferase (AST; 676 ± 433 and 634 ± 234 IU/L). Higher values for total proteins, albumin, glucose, and Na(+) in shovelnose sturgeon than in lake sturgeon probably are the result of handling stress. In addition, the plasma of male shovelnose sturgeon had higher concentrations of AST, glucose, and globulin than did that of females, whereas the plasma of females had higher concentrations of albumin and K(+) than that of males. This study is the first to report blood chemistry data for shovelnose sturgeon. Robust blood chemistry databases can be used by aquaculturists and fish managers for monitoring sturgeon health.     

免疫亲和色谱高效液相色谱法检测鲟鱼肌肉中常山酮的残留

试验建立了由免疫亲和色谱-高效液相色谱方法检测鲟鱼肌肉中常山酮的残留。样品经胰蛋白酶酶解,乙酸乙酯提取,再用0.125mol/l的醋酸铵缓冲液分离,经免疫亲和色谱柱净化,以乙腈-乙酸铵缓冲液-水为流动相(含0.1%三乙胺),反相液相色谱-紫外检测法检测,检测波长243nm。在20～200μg/kg添加浓度的范围内,样品回收率分别为75.4%～82.0%,变异系数分别为0.7%～8.6%。方法检测限为10μg/kg。结果显示:本方法灵敏度高,干扰少,重复性好。     

Serum electrolyte and nonelectrolyte status in freshwater juvenile Persian sturgeon Acipenser persicus

Status of serum electrolyte and nonelectrolyte variables can be used for managing sturgeon species cultured in freshwater or living in seawater. The aim of the present study was to evaluate serum biochemical variables in clinically healthy juvenile Persian sturgeon Acipenser persicus cultured in freshwater. Serum samples from 11 females and 10 males were analyzed, and levels (mean +/- SD) of the following variables were compared between sexes: glucose (Glc; 5.58 +/- 1.25 mmol/L for females and 8.56 +/- 1.80 mmol/L for males), total cholesterol (TC; 2.50 +/- 0.45 and 2.40 +/- 0.65 mmol/L), triglyceride (TG; 7.13 +/- 2.68 and 5.14 +/- 1.27 mmol/L), blood urea nitrogen (BUN; 1.28 +/- 0.2 and 1.01 +/- 0.2 mmol/L), total protein (TOP; 55.84 +/- 8.77 and 41.44 +/- 8.62 g/L), inorganic phosphate (P(i); 6.19 +/- 1.02 and 5.23 +/- 0.49 mmol/L), calcium (Ca; 2.80 +/- 0.43 and 2.63 +/- 0.32 mmol/L), magnesium (Mg; 0.9 +/- 0.23 and 0.99 +/- 0.22 mmol/L), sodium (Na; 152.80 +/- 13.81 and 156.38 +/- 12.67 mmol/L), potassium (K; 2.64 +/- 0.58 and 2.27 +/- 0.39 mmol/L), and chloride (Cl; 143 +/- 13.85 and 151.67 +/- 21.08 mmol/L). There were no differences in TC, Ca, Mg, Na, K, or Cl between sexes. The Glc value was lower in female Persian sturgeon than in males, whereas the values of TG, BUN, TOP, and P(i) were higher in females than in males. Freshwater adaptation may affect serum ion concentrations in juvenile Persian sturgeon.     

A single sea lamprey attack causes acute anemia and mortality in lake sturgeon

The effects of sea lamprey Petromyzon marinus parasitism on hematological variables have not been quantified for lake sturgeon Acipenser fulvescens. Our study objectives were to (1) assess changes in lake sturgeon hematology immediately after a single sea lamprey attack and after a 2-week recovery period and (2) assess changes in the histological condition of major hematopoietic organs. Lake sturgeon from four size-groups (470-570, 570-650, 650-760, and 950-1,500 mm fork length) were individually subjected to a sea lamprey attack in a series of 55 experimental trials. Survival of lake sturgeon after a single sea lamprey attack was size dependent, with fish in smaller size-groups exhibiting higher direct and indirect mortality than individuals in larger size-classes. The most sensitive blood chemistry variable was hematocrit: each 1% decline in hematocrit resulted in a 5.1% increase in mortality risk. Other important variables were plasma protein level, with a 10-g/dL decline resulting in a 4.2% increase in mortality risk; and hemoglobin, with a 1-g/dL decline resulting in a 2.9% increase in mortality risk. Most of the surviving lake sturgeon were unable to restore hemoglobin, hematocrit, and plasma protein to pre-attack levels by the end of the 2-week recovery period. We developed an index of histological spleen condition, which indicated that short-duration (< 5-d) sea lamprey attachments depleted red blood cell reserves faster than longer-duration attacks. Our study results indicate that sea lamprey parasitism has the potential to induce acute anemia in lake sturgeon and that nonlethal attacks on smaller (< 760-mm) fish can have serious physiological implications.     

中华鲟消化系统内消化酶活性分布

鲟鱼类是大中型的经济鱼类 ,广泛分布于北回归线以北的水域中。我国是世界上鲟鱼资源丰富的国家之一 ,长江除了中华鲟外还有白鲟、达氏鲟 ,其中白鲟只见于我国。而达氏鲟和中华鲟则是我国极有开发前途的一项自然资源 ,是科学研究的宝贵材料。中华鲟仔鱼期一般吃浮游动物 ;幼鱼期多以底栖的水生寡毛类、水生昆虫、小型鱼虾及软体动物为主要食物 ;成鱼期吃底栖动物或动植物渣滓。对于幼鲟的培育工作 ,国外多采用人工饲料培育幼鲟 ,既可进行规模化、集约化的养殖 ,又避免了单一使用水蚯蚓所带来的弊端。中国科学院水生生物研究所邓昕等人尝试采…     

噬菌蛭弧菌对鲟鱼免疫相关酶活性的影响

试验对鲟鱼基础饲料喷洒蛭弧菌制剂,喷洒量分别为0(对照组)、3、6、9mg/g,于30d后分别测定血清中免疫相关酶的活性,结果表明,相对于对照组,试验组的溶菌酶活性、AKP活性都极显著的增强(P<0.01);试验组的POD活性有显著的增强(P<0.05)。综合本次研究结果表明,饲料中添加蛭弧菌能对鲟鱼体内免疫相关酶系统产生积极的调理改善作用,使其非特异性免疫力得到改善与提高。结合养殖成本与文章结果得出的最低有效浓度,建议其适宜添加量为5～8mg/g。     

酶解鲟鱼鱼鳍制备蛋白粉的工艺研究

本试验对比研究3种蛋白酶水解鲟鱼鱼鳍的效果。结果表明:单酶水解选择胃蛋白酶为水解的最适酶种,双酶水解采用正交试验确定其最佳的复合酶种为胃蛋白酶加木瓜蛋白酶,水解条件为温度37℃和50℃、酶用量3000U/g、分别在最适pH2.5与pH6.5下水解6h、料比1∶2,蛋白质回收率可达到97.17%;经过酸浸预处理后水解液基本无腥苦味,经真空冷冻干燥可制得纯度83.65%的蛋白粉。     

史氏鲟饲料中脂肪的最适含量

本文报道了史氏鲟饲料脂肪最适含量的结果。试验饲料是以酪蛋白、鱼粉、糊精和纤维素等为主要原料配制而成的等氮（蛋白质含量４１％）和等能量的（１１．２ＭＪ／ｋｇ饲料）半精制饲料，以等量混合的海水鱼油、豆油作为添加的脂肪源，设０、２、４、６、８和１０％６种添加浓度。试验周期为２５ｄ。试验结果显示，增重率、饲料系数和蛋白质效率均以脂肪含量７．６％～９．６％的４、５组饲料最佳，比脂肪含量分别为１．６％和３．６％的１、２组饲料差异显著，但与脂肪含量分别为５．６％和１１．６％的３、６组饲料差异不显著。如果考虑到饲料成本，把史氏鲟饲料脂肪的最适合量设定在８％左右是合适的。     

Antioxidant supplementation,effect on post‐thaw spermatozoan function in three sturgeon species

High levels of reactive oxygen species (ROS), which may be associated with reduced sperm quality, can be detected during cryopreservation of sperm of some species. Our objective was to investigate whether the addition of antioxidants to cryopreservation extenders influenced post‐thaw sperm characteristics and fertility in Acipenser dabryanus, Acipenser sinensis and Acipenser baerii. Prior to freezing, sperm samples were diluted with a base extender as control or in extender supplemented with catalase (CAT), glutathione (GSH), cysteine (NAC), ascorbic acid (VC) or their paired combinations. Protective concentrations of CAT, GSH and VC in the three species were 25 U/ml, 0.25‐0.5 mg/ml and 0.5 mg/ml, respectively. Cysteine showed no protective effect against ROS. The addition of CAT, GSH and VC positively affected either acrosome or membrane integrity of post‐thawed sperm in the three species, as well as spermatozoan motility in A. sinensis. The combination of antioxidants did not show a positive synergistic effect. This study suggested that the use of antioxidants in the cryopreservation of sturgeon sperm has potential to decrease intracellular ROS, and consequently preserve acrosome and membrane integrity, as well as spermatozoan motility.     

人工养殖鲟鱼鱼鳍酶解蛋白粉的营养评价

采用胃蛋白酶加木瓜蛋白酶双酶水解法制备了人工养殖鲟鱼鱼鳍蛋白粉,并对鲟鱼鱼鳍酶解蛋白粉的营养成分进行了综合分析.结果表明:鱼鳍酶解蛋白粉的水分平均含量3.52%.灰分含量33.24%,总脂肪的平均含量0.60%,总糖含量0.30%,粗蛋白质含量64.56%,纯蛋白含量41.58%.鱼鳍酸解蛋白粉中氨基酸含量丰富(94.36%),其中必需氨基酸占氨基酸总量的19.28%;其矿物质含量也很丰富,其中钙、锌和硒含量分别高达4.2×102,68.7 mg/kg和0.52 mg/kg.     

人工养殖鲟鱼鱼皮酶解蛋白粉的营养评价

试验采用胃蛋白酶加木瓜蛋白酶双酶水解法制备人工养殖鲟鱼皮蛋白粉并对鲟鱼皮蛋白粉的营养成分进行了综合分析。结果表明:鲟鱼皮蛋白粉的水分平均含量0.98%、灰分含量2.47%、总脂肪的平均含量0.80%、总糖含量0.50%、粗蛋白含量98.75%、纯蛋白含量46.22%;含有丰富的氨基酸,其中必需氨基酸占氨基酸总量的15.78%,蛋白质营养价值高;矿物质含量较丰富,特别是钙元素和硒元素的含量,分别达到了2.7×104和0.37mg/kg。     

Observations and treatment of Nitzschia sturionis on Atlantic sturgeon from Chesapeake Bay

From 2004 to 2008, 10% of Atlantic sturgeon Acipenser oxyrinchus oxyrinchus examined during a bycatch study of Maryland's Chesapeake Bay were infested with the trematode Nitzschia sturionis on the skin and gills. The parasite intensity increased on 75% of infested fish 4-24 months after being placed in captivity. Mean parasite intensity increased to a greater extent on the skin (up to 100-fold) than on the gills (up to 16-fold). Atlantic sturgeon that were infested with N. sturionis gained weight at a reduced rate or lost weight compared with uninfested fish. Skin lesions associated with N. sturionis progressed from a few reddened foci to hemorrhagic ulcers and depigmentation, while gill lesions showed a less-dramatic progression. Host tissues identified in the intestinal ceca of N. sturionis consisted primarily of malpighian cells, but small amounts of blood were also found in worms attached to lesions in the skin and gills. An Atlantic sturgeon infested with approximately 500 worms was successfully treated with a 3-h bath of praziquantel at 10 mg/L. This first report of N. sturionis from Chesapeake Bay extends the parasite's reported southern range in North America.     

Endoscopic sex determination and gonadal manipulation in Gulf of Mexico sturgeon (Acipenser oxyrinchus desotoi).

Seventeen Gulf of Mexico sturgeons (Acipenser oxyrinchus desotoi) underwent endoscopic sex determination, gonadal biopsy, and various reproductive surgeries as part of a conservation development plan. The fish were anesthetized with tricaine methanesulfonate (MS-222) buffered with sodium bicarbonate and maintained on a recirculating water anesthesia circuit. A 6-mm Ternamian EndoTip Cannula, placed through the ventral midline, midway between pectoral and pelvic fins, permitted the introduction of a 5-mm telescope. Swim bladder aspiration and CO2 insufflation of the coelomic cavity provided excellent observation. Second and third cannulae were placed under direct visual control, lateral and cranial or caudal to the telescope cannula. Sex determination was successfully performed in all fish; however, five of 17 sturgeons (29%) required endoscopic gonadal biopsy to confirm sex. Bilateral ovariectomy or orchidectomy was successfully performed in three males and four females. Unilateral ovariectomy and bilateral ligation of the müllerian ducts using an extracorporeal suturing technique was accomplished in an additional three females. No apparent morbidity was associated with the anesthesia or endoscopic surgery in any fish. The ability to safely perform minimally invasive reproductive surgery in fish may have important management and conservation benefits.     

Surgical removal of cataracts due to Diplostomum species in Gulf sturgeon (Acipenser oxyrinchus desotoi).

Twenty 6-yr-old (1995-yr-class) Gulf of Mexico sturgeon (Acipenser oxyrinchus desotoi) were diagnosed as having bilateral cataracts. Histopathologic assessment of the lenses of two of the fish revealed the presence of a diplostomid trematode. Pharmacological treatment of the trematodes may be effective for killing the parasites, but the damage to the lenses and resulting cataracts are nonreversible. Because these animals were to be used in a subsequent study as sentinels in the natural environment, it was necessary to return the animals' vision to as close to normal as possible. Electroretinograms were performed on each fish's eyes to ensure that retinal function was present. Cataracts then were surgically removed by phacoemulsification and aspiration. The animals tolerated the surgical procedures well. This report is the first known report of surgical correction of cataracts in sturgeon species. It also is the first known attempt to correct vision problems in fish being returned to the wild.     

Calculation of protein and energy requirements in beluga sturgeon (Huso huso) using a factorial approach

This study tried to determine the protein and energy requirements of growing beluga sturgeon Huso huso using a factorial approach. The experiment was composed of four small‐scale growth trails covering different weight ranges. The fish fed at 0, 20, 40, 60, 80 and 100% of satiation. DWG had a steady increase throughout the experiment following a non‐linear equation as Y = 1.433 (±0.056) × Ln(X) ?2.740 (±0.261); r² = 0.99, p < 0.001, where Y = weight gain (g/day) and X = fish weight (g). The daily requirement of digestible energy (DE) for maintenance amounted to 79.09 kJ × BW (kg)^0.8. The daily requirement of DP for maintenance calculated as 0.93 g × BW (kg)^0.7. The relationship between DE intake (X) and DE gain (Y) expressed as Y = ?0.0004 (±0.000) X² + 0.600 (±0.082) X ?44.95 (± 6.72). Also, the relationship between DP intake (X) and protein gain (Y) was expressed as Y = ?0.019 (±0.006) X² + 0.548 (±0.062) X ? 0.498 (±0.121). The daily requirements of energy and protein were estimated as 79.09 kJ × BW (kg)^0.8 + 2.94 × DE gain and 0.93 g × BW (kg)^0.7 + 2.63 × DP gain. Apparently, beluga sturgeon is inefficient in converting energy and protein into body tissue. Therefore, energy content of the diet should be sufficiently high to satisfy large energy demands in beluga sturgeon and also to reduce the catabolism of protein.     

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.     

挤出滚圆-流化床包衣法制备鲟鱼饵料加工工艺研究

用良好的人工饵料取代生物饵料,可以降低鲟鱼的饲养成本。试验对挤出滚圆-流化床包衣法制备鲟鱼饵料的加工工艺进行了研究,得到了试验条件下的最佳工艺参数。结果表明采用挤出滚圆工艺加工鲟鱼饵料是可行的。     

Hematology and plasma chemistry reference intervals for cultured shortnose sturgeon (Acipenser brevirostrum)

BACKGROUND: The shortnose sturgeon, Acipenser brevirostrum, is an imperiled species distributed along the Atlantic coast of North America. Interest in replenishing wild stocks with hatchery-reared fish has created a need for accurate hematologic and biochemical reference intervals to evaluate the health of both fish raised in aquaculture systems and fish in the wild. OBJECTIVES: The objective of this study was to generate hematologic and biochemistry reference intervals for healthy shortnose sturgeon. METHODS: Blood samples were collected in heparinized tubes from 77 shortnose sturgeon raised in flow-through aquaculture systems. Whole blood and plasma samples were analyzed for hematologic and biochemical variables using standard techniques. Reference intervals were calculated as the central 95% (percentile) of data. RESULTS: Hematologic reference intervals (n = 46) were as follows: PCV 26-46%, hemoglobin 5.7-8.7 g/dL, MCV 307-520 fL, MCH 65.9-107.1 pg, MCHC 15-30 g/dL, plasma proteins (refractometry) 2.8-6.0 g/dL, RBC count 0.65-1.09 x 10(6)/microL, total WBC count 28,376-90,789/microL, small lymphocytes 9063-56,656/microL, large lymphocytes 2122-10,435/microL, neutrophils 3758-33,592/microL, monocytes 0-7137/microL, eosinophils 0-1544/microL, thrombocyte-like cells 6863-23,046/microL, thrombocytes 32,205-122,179/microL, and neutrophil:lymphocyte ratio 0.068-1.026. Plasma chemistry reference intervals (n = 77) were as follows: total protein 2.7-5.3 g/dL, albumin 0.8-1.7 g/dL, globulins 1.8-3.7 mg/dL, creatinine 0-1.4 mg/dL, total bilirubin 0-0.1 mg/dL, alkaline phosphatase 47-497 U/L, aspartate aminotransferase 90-311 U/L, sodium 124-141 mmol/L, potassium 2.9-3.7 mmol/L, chloride 106-121 mmol/L, calcium 6.6-12.1 mg/dL, magnesium 1.6-2.3 mg/dL, phosphorus 5.1-8.1 mg/dL, glucose 37-74 mg/dL, cholesterol 42-133 mg/dL, and osmolality 232-289 mOsm/kg. CONCLUSION: Reference values reported here will be useful for the early detection, identification, and monitoring of disease and sublethal conditions in cultured shortnose sturgeon.