美国大盐湖卤虫业情况及我国卤虫产业状况

本文介绍了美国大盐湖卤虫业情况,同时介绍了我国卤虫卵生产状况,并就国内卤虫生产情况和国际形势提出了看法。     

Wasted fishery resources: discarded by-catch in the USA

Fishery by‐catch, especially discarded by‐catch, is a serious problem in the world's oceans. Not only are the stocks of discarded species affected, but entire trophic webs and habitats may be disrupted at the ecosystem level. This paper reviews discarding in the marine fisheries of the USA; however, the type, diversity and regulatory mechanisms of the fisheries are similar to developed fisheries and management programmes throughout the world. We have compiled current estimates of discarded by‐catch for each major marine fishery in the USA using estimates from existing literature, both published and unpublished. We did not re‐estimate discards or discard rates from raw data, nor did we include data on protected species (turtles, mammals and birds) and so this study covers discarded by‐catch of finfish and fishable invertebrates. For some fisheries, additional calculations were required to transform number data into weight data, and typically length and weight composition data were used. Specific data for each fishery are referenced in Harrington et al. (Wasted Resources: Bycatch and discards in US Fisheries, Oceana, Washington, DC, 2005). Overall, our compiled estimates are that 1.06 million tonnes of fish were discarded and 3.7 million tonnes of fish were landed in USA marine fisheries in 2002. This amounts to a nationwide discard to landings ratio of 0.28, amongst the highest in the world. Regionally, the southeast had the largest discard to landings ratio (0.59), followed closely by the highly migratory species fisheries (0.52) and the northeast fisheries (0.49). The Alaskan and west coast fisheries had the lowest ratios (0.12 and 0.15 respectively). Shrimp fisheries in the southeast were the major contributors to the high discard rate in that region, with discard ratios of 4.56 (Gulf of Mexico) and 2.95 (South Atlantic). By‐catch and discarding is a major component of the impact of fisheries on marine ecosystems. There have been substantial efforts to reduce by‐catch in some fisheries, but broadly based programmes covering all fisheries are needed within the USA and around the world. In response to international agreements to improve fishery management, by‐catch and discard reduction must become a regular part of fishery management planning.     

Seasonal habitat use by brook trout,Salvelinus fontinalis (Mitchill), in a second-order stream

Abstract Seasonal habitat use by over-yearling and under-yearling brook trout, Salvelinus fontinalis (Mitchill), was examined in a second-order stream in north-central Pennsylvania, USA. The habitat occupied by brook trout and available habitat were determined in a 0.5-km stream reach during the spring, summer and autumn of 1989 and the spring and summer of 1990. Cover, depth, substrate and velocity were quantified from over 2000 observations of individual brook trout. Habitat used by under-yearling brook trout was more uniform between seasons and years than that used by over-yearling brook trout. Over-yearling brook trout occupied areas with more cover and greater depth than did under-yearling brook trout, suggesting ontogenetic shifts in these variables. Differences for velocity and substrate were not as great as those for cover and depth. The selection of areas with low water velocities governed trout habitat use in spring, whereas cover and depth were the most important habitat variables in summer and autumn. Principal component analysis showed that available habitat and trout habitat centroids diverged most in spring, indicating that habitat selection by brook trout may be greatest at this time.     

美国西瓜育种历程及育成品种的种质基础

 在对美国1870～2001年育成的235个西瓜品种选育方法及系谱分析的基础上，概括了美国一百多年间的西瓜育种发展历程，计算了91个通过杂交选育的品种直接亲本和祖先亲本的核遗传贡献值，评定出核心直接亲本和核心祖先亲本及核心中间亲本，并对如何重点引进和有效利用这些核心种质进行了讨论。     

对美国渔业管理模式的初步探讨

美国的渔业法规体系经过几十年的制定和修订已趋完善。目前的管理现状首先是重视立法和执法，并实现了由生产型向管理型、由对资源和一半的管理转为对人的管理，并用科研指导管理，设立渔区管理理事会，发挥群众的管理作用。与美国的管理模式相比， 中国首先应该改善管理体制、加强科研投入、建立渔民协会发挥群众的管理作用。试图通过探讨美国的渔业管理模式，和我国目前所应用的渔业管理进行对比分析，从中找出可供我国学习并借鉴的方面，并得出一些初步的设想与建议，以供有关渔业管理部门参考。     

美国农产品地标保护的做法及对中国的启示

美国农产品的地理标志保护历史源远流长,形成了鲜明、成熟的体系,对于中国完善地理标志保护体系有着重大的借鉴作用。中国具有极其丰富的农产品资源,然而在法律层面上的保护却有所欠缺,因此导致了许多直接或间接的经济损失。分析中美间农产品贸易现状数据,探讨美国对于农产品地理标志保护的法律体系,从美国和其他国对于地理标志谈判的案例吸取经验,为中国建立完善农产品地标保护的做法提供一些启示。     

新美系大约克夏原种猪生长期饲粮适宜能量、粗蛋白和钙磷水平的研究

选择胎次、断奶日龄及年龄基本相近,体重为(20±1)kg的健康新美系大约克夏原种猪72头,采用四因素三水平的L9(34)正交试验,研究不同能量、粗蛋白、钙和磷水平对生长期新美系大约克夏原种猪生产性能、营养物质表观消化率和血清生化指标的影响。结果表明:①能量对日增重的影响达到显著水平(P<0.05);②能量、粗蛋白、钙和磷对能量表观消化率的影响达到极显著水平(P<0.01),粗蛋白、钙和磷对粗蛋白、粗纤维表观消化率的影响均达到极显著水平(P<0.01),能量对磷表观消化率的影响达到极显著水平(P<0.01),能量、粗蛋白、钙对粗脂肪表观消化率的影响达到极显著水平(P<0.01);③能量对血清总胆固醇(T-Cho)和血清甘油三酯的影响达到显著水平(P<0.05),蛋白质对血清蛋白(Alb)的影响达到极显著水平(P<0.01)。新美系大约克夏原种猪的适宜营养水平为:能量14.23kJ/kg,蛋白质21.5%,钙0.8%,磷0.8%。     

美国树木城市评选对我国城市林业建设的启示

美国树木城市创建活动始于1976年,迄今已有近4 000个不同规模的城市或社区获此殊荣,近1亿美国人工作和生活在树木城市中。美国树木城市的标准体系相对简单,且以定性指标为主,强调城市林业的法制建设和组织宣传,城市林业长期发展规划,政府部门与民间团体、非政府组织和广大居民的参与及协调;并辅以树木城市发展奖励指标体系促进可持续发展。分析美国树木城市申报的标准、认定过程和城市林业建设的理念,对于我国建立与完善国家森林城市评选指标体系和城市林业建设法规,促进我国城市林业建设生态、高效和可持续发展有一定的借鉴意义。     

美国烟草经济政策对我国现代烟草农业建设的启示

论述了美国烟草经济政策的沿革,并根据经济政策对烟草生产的影响将美国烟草种植分为自由种植、配额种植和合同种植3个阶段;阐述了烟草配额买断和对美国烟草种植业的影响;探讨了美国经济政策变化对我国烟草现代化建设的启示。     

基于MODIS EVI的冬小麦产量遥感预测研究

Terra-MODIS数据集同时具有归一化植被指数（NDVI）和增强型植被指数（EVI）两种植被指数。为了对比这两种植被指数在农作物估产中的应用效果，该文利用MODIS-NDVI和MODIS-EVI作为遥感特征参量，以对美国冬小麦的长势监测与产量预测为例进行了研究：运用区域作物特定生育期内多年的NDVI和EVI值与作物产量进行相关分析，采用一次线性拟合方法分别建立回归方程，估算当年的农作物产量。结果表明，EVI明显地比NDVI更好地与产量建立回归方程，用EVI建立的回归方程，各州相关系数大多在0．7以上；而用NDVI建立的回归方程，相关性不稳定。因此利用EVI建立的模型对2004年美国冬小麦进行估产，并将预测结果与美国国家统计署6月1号公布的预测结果进行对比，结果发现，美国国家统计署预测单产误差为3．05％，总产误差为-2．56％，而该研究预测结果单产误差为2．62％，总产误差为-1．77％且预测时间比美国国家统计署预测时间提前约半个月。可见EVI可以更有效地进行作物监测及估产，提高预测的准确性。