鲜活大菱鲆溯源标识固定工艺研究及参数优化

为获取鲜活大菱鲆(Scophthalmus maximus)溯源标识固定工艺,分别采用细耳标扣、T型扣与套环扣进行鱼体固定试验,对比各组的钉扣固定速率与钉扣有效固定率,评价不同钉扣固定后鱼体状态指标,选出最合适的钉扣.在此基础上,对比鱼体不同部位鳍体的固定效果,并对钉扣固定位置范围参数进行优化试验.结果表明,采用T型扣...     

加热条件下鱼翅结构和物性学参数变化

研究了鱼翅在不同加热时间(1、2、3、4 h)条件下组织构造及其物性学参数(凝胶强度、最大破断应变、剪切应力、破断强度)变化,并测定了胶原蛋白含量。通过扫描电子显微镜镜观察鱼翅的组织构造,采用质构仪测定其物性特性。结果表明,随着加热时间的延长,鱼翅的物性学参数变化显著,总体呈减小趋势。加热3 h后即可达到鱼翅较好质构。     

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.     

鲢鱼生物学性状研究

鲢鱼又名白鲢、跳鲢、鲢子鱼等。属鲤科、鲢亚科。鲢鱼具有生长快、疾病少、不需专门人王投饵的特点。利用鲢鱼实测体全长,体重数据进行线性回归分析,得出鲢鱼的体全长和体重之间呈曲线相关关系,相关公式为W=0.011L^3.077R=0.9919。     

箱型承水挡诱导漂子技术参数研究

本课题通过系列水工模型试验,对箱型承水挡诱导漂子的技术参数进行了分析研究,得出了它们之间的相互关系,并建立了导漂轴线与水流方向夹角和流速、导漂纵向拉力和流速之间的关系式。此外,还对漂子的工作状态进行了分析研究。这些分析研究成果,将对从事木材水运事业的设计、生产单位具有实用意义。     

中国鱼翅消费与鲨鱼捕捞关系初步研究

近年来,鲨鱼资源养护和管理成为国际社会关注点,中国的鱼翅消费被认为是破坏鲨鱼资源的罪魁祸首。为了解事实,采用问卷调查法于2017年对中国鲨鱼产品主要批发市场(北京、上海、广州)的商户进行调查。结果显示:经营种类以鱼翅为主;鱼翅销量和价格的最高峰阶段为2008—2012年,2013年开始,销量和价格均急剧下降,最低峰阶段为2015—2016年,且2017年较2016年相比,销量和价格继续下跌; 60%的商户反映经营状况不佳。海关数据表明,中国内地干鱼翅进口量由2004年的最高峰4 776 t降到2012年的108 t,且2013—2016年持续下降。而联合国粮农组织(FAO)发布的数据显示全球鲨鱼捕捞量在2013—2016年整体平稳,全球鲨鱼捕捞量并未随中国鱼翅消费的下降而下降。故把中国消费鱼翅作为破坏鲨鱼资源的罪魁祸首是失实的。     

应用遗传算法优化设计汽车散热器

根据减少耗材的要求,本文将遗传算法应用于管带式汽车散热嚣的优化设计。提出了散热器芯体结构参数优化的方案,详细讨论了优化算法的步骤及流程,最后,通过实例表明该方法能得到较好的优化结果。     

Understanding pressures on fishery resources through trade statistics: a pilot study of four products in the Chinese dried seafood market

This study investigates the dried seafood trade, centred in Chinese markets, in order to better understand the pressures its demand exerts on global marine resource stocks. Using Hong Kong, the region's largest entrepôt, as a focal point, the trade in shark fins, abalone, bêche‐de‐mer and dried fish is characterized in terms of product history, volume, source fisheries and species composition. Trends identified in the Hong Kong market are interpreted in the context of the larger Chinese market. Shark fin imports grew 6% per year between 1991 and 2000, most likely because of market expansion in Mainland China, posing increasingly greater pressures on global shark resources. In contrast, the quantities of dried abalone traded through Hong Kong remained steady, but inferences based on this trend are discouraged by suggestions of increasing preferences for fresh product forms and growing domestic production in Mainland China. Hong Kong's imports of dried bêche‐de‐mer (sea cucumber) have decreased, while the percentage of imports re‐exported has remained steady, suggesting that Hong Kong continues as an entrepôt for Mainland China despite declining domestic consumption. Few conclusions can be drawn regarding dried fish products, including whole fish and fish maws, because of a lack of product differentiation in customs data, but a market survey was conducted to provide information on species composition. Comparison of Hong Kong dried seafood trade statistics to those of other key trading partners indicates that, in general, Hong Kong's duty‐free status appears to encourage more accurate reporting of traded quantities. Under‐reporting biases ranged from 24 to 49% for shark fin and bêche‐de‐mer, respectively. Comparison to United Nations (UN) Food and Agriculture Organization (FAO) databases indicates additional under‐reporting for shark fin such that an alternative minimum estimate of world trade is at least twice the FAO estimates in 1998–2000. The results of a survey of Hong Kong traders provide insight into their attitudes toward harvest, economic and regulatory factors, and suggest that conservation efforts are unlikely to emerge from, or be actively supported by, dried seafood trade organizations. The market's apparent sensitivity to economic sentiment, however, reveals an opportunity for consumer education to play a role in shaping future market growth and resource conservation. Recommendations are provided for improving trade statistics and for developing better analytical techniques to complement traditional methods for monitoring the exploitation and management of fisheries resources.