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。     

史氏鲟鱼硫酸软骨素的提取及抗肿瘤活性的研究

以史氏鲟鱼软骨为原料,按碱提酶解醇沉的工艺流程,进行硫酸软骨素的碱提工艺优化研究。分别通过碱浓度、碱液温度、碱液量的单因素试验及该3个因素的正交试验,研究其对产品得率及其氨基己糖含量的影响,综合分析得出最佳的碱提工艺为2倍量6%的NaOH,于40℃的水浴中搅拌提取4h;该工艺条件制备鲟鱼硫酸软骨素的得率可高达40.45%,产品质量符合硫酸软骨素口服片(WS1-C3-0030-2000)标准的要求。鲟鱼硫酸软骨素精品和粗品对3种细胞乳腺癌细胞株(MCF-7细胞)、胃癌细胞株(MGc803细胞)、肝癌细胞株(SMMC7721)作用72h时,其IC₅₀分别为7.28mg/mL、7.68mg/mL、4.25mg/mL和8.86mg/mL、9.27mg/mL、7.37mg/mL,与鲨鱼硫酸软骨素精品和粗品有着相似的抗肿瘤活性。     

我国鲟人工养殖业面临的机遇与挑战

简述了鲟人工养殖业在我国的发展历程与现状,以及鲟人工养殖业目前所存在的问题;探讨了鲟人工养殖也面临的机会——养殖雌性鲟成鱼,加工鱼子酱,并简要介绍鱼子酱的价值及其加工工艺,为我国鲟人工养殖业在未来几年的发展指明了方向。     

长江口中华鲟幼鲟补充量波动特征分析

长江口中华鲟自然保护区是中华鲟幼鲟入海前调节和索饵的重要场所,研究该水域幼鲟补充量特征的长期变化规律对于保护该物种具有重要意义。通过研究2005-2013年幼鲟数量和生物学特征的监测数据发现:(1)不同年份间长江口水域中华鲟幼鲟的初次见苗时间、最后退苗时间和时间跨度存在较大波动;(2)幼鲟补充量在监测期内总体呈现下降趋势,年际波动也非常明显;(3)方差分析显示,不同年份间幼鲟的平均全长和平均体质量存在显著性的差异(P0.05);(4)相关分析结果表明,幼鲟的平均全长与最后退苗时间之间存在较高的相关性(R=0.719 6,P0.05),这也许可以解释2007年平均全长偏高的异常现象。     

保鲜处理对冷鲜鲟鱼肉特征性风味成分的影响

为明晰保鲜处理对冷鲜鲟鱼肉冷藏期间的特征性风味物质的影响。本实验利用固相微萃取—气相色谱—质谱联用(SPME-GC-MS)结合电子鼻和电子舌技术,对经微酸性氧化电解水和ε-聚赖氨酸两步法保鲜处理的冷鲜鲟鱼肉在冷藏期间的挥发性成分和滋味成分进行分析。电子鼻能够对挥发性成分从整体上进行分析,贮藏后期保鲜处理组和对照组的鲟鱼肉挥发性气味的数据集无重叠区域,差异明显。利用SPME-GC-MS定性鉴定出46种挥发性物质,主要包括醛类、酮类、烃类和醇类等物质,其中己醛、庚醛、苯甲醛、辛醛、壬醛、癸醛和2,5-辛二酮、苯乙酮、3,5-辛二烯-2-酮为保鲜处理组的主要挥发性物质,保鲜处理延缓了冷鲜鲟鱼肉腥味的产生以及鱼肉香味的下降。电子舌检测冷藏过程中鲟鱼肉的滋味物质时发现,保鲜处理组苦味、涩味、咸味均低于对照组,两组样品贮藏6 d后,在苦味、涩味、咸味、鲜味方面均呈显著差异。保鲜处理起到了减缓冷藏期间冷鲜鲟鱼肉风味物质下降的作用,为保鲜处理在冷鲜鲟鱼肉中的应用提供了一定的理论基础。     

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.     

Determination of optimal feeding rates for juvenile lake sturgeon (Acipenser fulvescens) fed a formulated dry diet

Two 3‐week growth trials were performed to determine the optimum feeding rate of juvenile lake sturgeon (Acipenser fulvescens) fed with a semi‐purified dry diet (protein, 440 g; lipid, 130 g/kg) at different feeding rates: 5, 10, 20, 30, and 40 g/kg body weight per day (BW/.d‐1), for 36 g‐sized fish; and 2.5, 5, 10, 20, and 30 g/kg BW/.d‐1, for 80 g sized fish. Feeding rates significantly influenced growth performances, feed conversion ratio, wholebody lipid and moisture contents, energy and protein retention, and fasted blood glucose levels (p < 0.05). The ratio of total C/total N measured in whole fish was positively correlated to the feeding rates and the lipid contents of whole fish. Suboptimal feeding significantly depressed growth performance and protein synthesis based on the measurement of RNA/DNA ratio in white muscle. Based on polynomial regression models, an optimal feeding rate to support the maximum growth, protein and energy retention was 34.5, 22 and 27.3 g/kg BW/.d‐1, respectively, for fish sized at 36–72 g; and 29.0, 16.9 and 19.9 g/kg BW/.d‐1, respectively for fish sized at 80–140 g. Results of this study will benefit future research to develop practical feeds to replace frozen live feed and feed management for lake sturgeon.     

Emigration of hatchery‐reared Pallid Sturgeon,Scaphirhynchus albus (Forbes and Richardson), through a Missouri River dam

The middle Missouri River (MMR; Fort Randall Dam, SD to Gavins Point Dam, NE‐SD) is stocked with hatchery‐reared pallid sturgeon, Scaphirhynchus albus (Forbes and Richardson), from upper Missouri River broodstock to aid recovery of this federally endangered species. Emigration of these fish through Gavins Point Dam restores genetic connectivity that likely existed pre‐impoundment but could lead to outbreeding depression in the future. Recapture data of hatchery‐reared pallid sturgeon stocked in the MMR were evaluated to improve understanding of pallid sturgeon emigration. From 2004 to 2015, 219 emigrants were caught: 4 stocked at age ≥2 years and 215 stocked at age ≤1 year. Emigration of the 2001‐2007 year classes stocked at age 1 was a consistent phenomenon and appeared higher than emigration of year classes stocked at ages 2–3. Little evidence suggested emigration was associated with an unusually high‐water event in 2011. The annual emigration probability of individuals stocked at age 1 estimated from multi‐state mark–recapture models was 0.05 [95% confidence interval = 0.04–0.06] for fish ages ≥1 year. This study suggests that alterations to stocking practices (e.g. stocking age) may affect emigration rates and, therefore, connectivity among pallid sturgeon populations.     

Impact of starvation on digestive enzymes activities and plasma metabolites in Siberian sturgeon (Acipenser baerii,Brandt, 1869)

To increase the current knowledge about the relationship between nutritional status and the digestive capacity of Siberian sturgeon (Acipenser baerii), we addressed the effect of starvation‐refeeding and macronutrient composition on growth parameters and key digestive enzyme activities in A. baerii. Acipenser baerii juveniles were fed four different diets for 3 weeks, then starved for 2 weeks and allowed to refed for 5 weeks with the same diets. Another group of fish were fed 10 weeks with the corresponding diets. Among 10‐week fed fish, high‐protein diets promoted higher body weight values, while the lowest specific growth rate was observed in fish fed a low‐protein, medium‐carbohydrate, high‐lipid diet (p < .05). At the end of the experiment, in fish refed for 5 weeks following a feeding‐starvation cycle and in 10‐week fed animals, the higher levels of blood glucose, triglycerides and cholesterol were found in fish fed low‐protein diets (p < .05). In all treatments, 2 weeks of starvation decreased α‐amylase activity in the intestine (p < .05), while 4 days of refeeding increased lipase (p > .05) and α‐amylase activity in the intestine as well as pepsin in the stomach (p < .05). Our findings suggest that A. baerii maintains a high capacity to digest proteins and lipids after 2 weeks of starvation and that α‐amylase can be used as an indicator of the nutritional status in fish submitted to starvation‐refeeding cycles. Indeed, refeeding with high‐protein and CHO:L ratio diets after starvation could improve the growth rate of A. baerii in culture.     

The effects of different fishmeal level diets with or without phytase supplementation on growth performance,body composition,digestibility, immunological and biochemical parameters of juvenile hybrid sturgeon (Acipenser baeri Brandt ♀ × A. schrenckii Brandt ♂)

A 12‐week growth trial was conducted to evaluate the effect of low fishmeal and phytase replacing inorganic phosphorus on juvenile hybrid sturgeon (Acipenser baeri Brandt ♀ × A. schrenckii Brandt ♂). Four experimental diets were designed as FM100p, FM100, FM250p and FM250, which represented 10% and 25% fishmeal with or without phytase, respectively. The results showed that although growth parameters had no significant difference in all treatments, low fishmeal obviously decreased the culture cost of hybrid sturgeon. Lipid content of body composition was obviously increased in low fishmeal treatments (p < .05). The interaction of low fishmeal and phytase significantly enhanced apparent digestibility coefficients of crude protein (p < .05). Two‐way ANOVA analysis showed that input and output of phosphorus were significantly affected by fishmeal level, phytase and interaction of both factors (p < .05). For the immunological and hepatic function parameters, fishmeal level and phytase had significant effects on the activities of lysozyme, myeloperoxidase, malondialdehyde, alanine aminotransferase, lactate dehydrogenase and alkaline phosphatase (p < .05). The present study potentially justifies that a diet containing 10% fishmeal can be used for hybrid sturgeon. Moreover, replacement of monocalcium phosphate by phytase not only has no adverse effect on the growth of hybrid sturgeon, but also reduces phosphorus emission and protects aquaculture environment.