An additional life-history tactic of masu salmon: Migration of parr to coastal habitats     

Mari Kuroki  Tsuyoshi Tamate  Kentaro Morita 《Ecology of Freshwater Fish》2020,29(3):495-501

Alternative life-history tactics of masu salmon Oncorhynchus masou are well documented. Subsequent to the freshwater parr stage (age ≥ 1 + years), an anadromous form migrates to the sea after smolting, while a resident form matures without seaward migration. In addition to this typical migratory dimorphism, anecdotal reports based on field observations have indicated that some underyearling masu salmon use estuarine waters. However, no empirical evidence indicates saltwater utilisation and subsequent survival in the early parr stage. Here, we used otolith microchemistry to examine whether a portion of masu salmon parr in northern Japan enters coastal habitats. The otolith Sr:Ca ratios of most juveniles collected from six rivers had consistently low values, indicating that masu salmon parr inhabiting these rivers stay only in freshwater. In contrast, in individuals from a steep-gradient river the Sr:Ca ratios increased at about a 200-µm distance from the otolith core. These results suggest that some masu salmon parr might use brackish water or sea water temporarily. In addition, three masu salmon parr were found in another steep river where a culvert located only ten metres from the river mouth completely blocked upstream migration for spawning. The Sr:Ca ratios in these fish increased at about >200 µm from the otolith core, indicating the parr had immigrated to the non-natal river from the sea. Such flexible behaviour at an early life stage may contribute to the spatial expansion of masu salmon, and the movement could moreover help to stabilise its population dynamics.  相似文献   

长江中游稻区水稻产业发展现状、问题与建议   总被引：2，自引：0，他引：2  

赵正洪  戴力  黄见良  潘晓华  游艾青  赵全志  陈光辉  周政  胡文彬  纪龙 《中国水稻科学》2019,33(6):553-564

为了解国家调低稻谷保护收购价后长江中游稻区水稻产业发展状况,湖南、湖北、江西和河南4省水稻专家组织开展了相关调研。结果表明,长江中游稻区2018和2019（预测）两年水稻总体种植面积持续缩减,主要是湖南和江西“双改单”和种植结构调整所致,而湖北和河南面积略有增加。稻区内2018年稻谷销售进度明显滞后于上年同期,稻谷价格也不同程度下跌。这主要受国家保护价下调影响。而优质稻谷销售进度和价格受影响较小,其流通表现出更强的市场化。2018年水稻种植人工、地租、化肥和总成本均出现不同程度提高,其中地租和人工成本增加是总成本提高的主要原因。2018年稻米加工企业稻谷收购量、收购价和稻米批发价均不同程度降低。稻区内优质稻和杂交稻种植面积占比均为64%;籼稻面积占比97.6%。不同水稻种植技术应用比例表现为抛秧>手插和直播>机插;再生稻种植面积不断增加,稻渔模式迅猛发展。同时,稻区水稻产业发展面临着农民种粮积极性普遍下降,订单农业发展风险重重,农业基础设施不完善、修缮主体不明确,农业生产社会化程度偏低,稻渔模式无序发展隐患大,农民卖粮难度大、成本高、风险大,区域稻米品牌建设亟待加强等一系列问题。建议政府调整粮食收储政策,加强对农业的政策和补贴支持力度,加强对再生稻和稻渔模式发展的引导,加大科研攻关投入。  相似文献   

杂交稻圣优996主要特征特性及栽培技术要点     

谢勇 《福建稻麦科技》2014,(3):51-52

圣优996系福建科力种业有限公司与南平市农业科学研究所育成的中籼三系杂交稻新品种，2014年通过福建省品种审定。建阳市引进圣优996种植，观察了其主要特征特性，总结出高产栽培技术要点，为大面积推广应用做好技术储备。  相似文献   

Comparisons of Photosynthetic Characteristics in Relation to Lint Yield Among F_1 Hybrids,Their F_2 Descendants and Parental Lines of Cotton     

FENG Guo-yi  ;GAN Xiu-xia  ;YAO Yan-di  ;LUO Hong-hai  ;ZHANG Ya-li  ;ZHANG Wang-feng 《中国农业科学(英文版)》2014,(9):1909-1920

We compared the photosynthetic characteristics in relation to yield of two F1 cotton hybrids（Shiza 2-F1 and Xinluzao 43-F1）, their parental lines（NT2, H2 and 4-14） and their F2 descendants at different growth and development stages. The two F1 exhibited heterobeltiosis in net photosynthetic rate（Pn） by 8.1-52.1%, canopy apparent photosynthetic rate（CAP） by 8.2-57.6% and canopy respiration rate（CR） by 3.0-78.7% during the growing season. They also exhibited mid-parent heterosis by 2.0-5.2% in leaf chlorophyll content（SPAD） during the late growth and development stages. Regression analysis showed that both parents contributed to increase in Pn, SPAD and CAP in the F1. A low CR in the F1 matched a low CR of the parental line. Photosynthetic characteristics in the F2 were mainly dependent upon the magnitude and degeneration rate of the F1. Mid-parent heterosis in CAP and in CR during the late growth and development stage reduced the degeneration of the F2. Average dry matter accumulation was 10.7-34.7% higher in the parental lines of Xinluzao 43-F1 than in the parental lines of Shiza 2-F1. Heterobeltiosis in dry matter accumulation was 7.0-23.1% greater for Xinluzao 43-F1 than for Shiza 2-F1. Dry matter accumulation in the F1 was affected by either the dry matter accumulation of parents or heterobeltiosis. Dry matter accumulation in the F2 was mainly influenced by dry matter accumulation in the F1. The yields of the two F1 were 39.1-46.3% higher than their respective parents and 26.4-45.9% higher than that of the conventional cultivar Xinluzao 33. The yields of the two F2 were 9.2-12.8% higher than the parents and 14.9-27.4% higher than that of Xinluzao 33. The photosynthetic production and yield of the F1 and F2 were higher than that of their parents. The increases in Pn and CAP of the F1 and F2 were dependent on the photosynthetic characteristics of their parents. It is thus concluded that the photosynthetic performance, light use efficiency and yield of the F1 can be improved by using at le  相似文献   

封闭流水式网箱养殖混合供电系统设计     

许明昌 《渔业现代化》2017,44(6)

封闭流水式网箱养殖优点是零排放无污染,符合环保养殖要求,缺点是水质容易恶化,水交换与排污能耗大。为了降低能耗并确保设备正常运行,研发太阳能-市电-柴油发电机混合供电系统。基于蓄电池充放电特性,采用最大功率点跟踪(MPPT)和数字信号处理(DSP)技术实现太阳能智能充放电控制与保护,应用双电源自动转换开关技术实现有序混合供电。太阳能月均发电量250 k W·h,日均供电8.3 k W·h,满足负载日均耗电6.6~8.8 k W·h要求。结果表明,在阳光充足情况下,以太阳能供电为主;当出现连续阴雨天气情况下,供电顺序为蓄电池(充满状态可放电3~4 h)、市电、柴油发电机。随着太阳能系统性价比的提高,节能效果将更加明显。  相似文献   

稻文化的再思考(7)——稻的起源、分化和传播     

庞乾林  魏兴华  林海  王志刚  王磊 《中国稻米》2014,20(5):36-41

综述和讨论了稻的起源、分化和传播等的考古与现代生物学研究的一些成果。笔者根据这些研究成果描绘了稻的起源和传播路线,即稻起源于我国长江中下游地区或华南地区,分化成籼粳稻后一路向北传播至我国的北方,最后到达日本和朝鲜等国家(以粳稻为主);另一路向南和西南方向传播至我国西南地区和福建等地,再经我国西南地区传至缅甸、越南、印度等东南亚、南亚国家(以籼稻为主),最后经印度传至欧洲美洲,从福建经台湾和琉球群岛传至日本。稻的分化亦有多种研究成果和推论,但从籼粳重要的栽培特征和农艺性状基因看,一次起源的可能性更高。文中还穿插介绍了稻的起源和传播中的一些人文传说和神话故事。  相似文献   

早期热习服对肉鸡耐热力发育的影响研究进展     

邓胜齐  顾宪红 《中国畜牧杂志》2008,44(3):55-59

从早期热习服的概念、耐热力的评价指标以及早期热习服的时机出发,总结与分析了早期热习服对肉鸡后期耐热力形成的影响规律,试图探索出早期热习服提高肉鸡后期耐热力的机理。  相似文献   

Effects of stocking density on oxidative stress status and mammary gland permeability in early lactating dairy cows     

Shi‐xin Lin  Jian‐xin Liu  Kai‐ying Wang  Di‐ming Wang 《Animal Science Journal》2019,90(7):894-902

The current study was conducted to investigate the effect of stocking density (SD) on oxidative stress status and mammary gland permeability in early lactating dairy cows. Thirty‐two dairy cows were allocated into 16 blocks, basing on parity, previous milk yield, and body weight, and were then randomly assigned into one of the two treatments as follows: 75% (75SD) and 100% (100SD) SD. The cows were fed with same diet throughout the 8‐week experimental period. The milk yield and milk sample were collected on two consecutive days during the 8‐week experimental period weekly. Plasma samples were collected on fourth and eighth experimental weeks. Raw, energy‐corrected, and 4% fat‐corrected milk yield were significantly higher in 75SD‐cows than that of 100SD‐animals, respectively. The milk somatic cell count was lower in 75SD‐cows than that of 100SD‐animals. The levels of Na⁺, Na⁺/K⁺, bovine serum albumin and plasmin were lower in 75SD‐cows than those of 100SD‐cattle, respectively. The 75SD‐cows had reduced insulin and insulin/glucagon levels but higher prolactin and growth hormone concentrations, compared with those of 100SD‐animals, respectively. In conclusion, compared with low SD‐animals, early lactating cows with higher SD had higher oxidative stress status, which further led to a greater mammary gland permeability.  相似文献   

全模拟自然生态条件下杂交野猪繁育与肥育性能测定     

张金合  赵伍祥 《畜牧与饲料科学》2019,40(3):53-56

为了研究杂交野猪的生长性能、繁育水平与养殖环境、运动量、饲料配制的关系,根据野猪生活习性,对杂交野猪放养区内生活环境进行模拟(包括野猪巢穴、生态环境、植被),使杂交野猪能够有更多的运动范围和获取野外食物的机会。结果表明,放养模式下的杂交野猪产仔率(P<0.05)、仔猪存活率(P<0.01)均高于圈养模式杂交野猪,但增重速度显著(P<0.05)低于圈养模式下饲养杂交野猪。由试验结果可以得出,圈养模式下杂交育肥野猪增重速度显著高于放养杂交野猪,饲养管理难度较低,适合集约化大规模饲养。  相似文献   

萨杜湖杂交羊生长性能、羊毛品质及血液生理生化指标测定     

施会彬  王玉琴  何翁潭  吴至博  田志龙  余祖华  丁轲  赵战勤 《中国畜牧兽医》2019,46(2):404-413

为研究萨福克羊×杜泊羊×湖羊杂交羊(萨杜湖杂交羊)生长发育情况及其对当地生态环境的适应能力,采用生产性能常规测定、显微测定和全自动血液生理生化分析仪分别测定了不同年龄阶段萨杜湖杂交羊的体重、体尺指标、羊毛品质(包括不同部位羊毛的净毛率、细度、有髓毛和无髓毛占比、自然长度和伸直长度等指标)和成年羊血液生理生化指标。结果表明:萨杜湖杂交羊早期生长速度较快,初生阶段及周岁时公羊体斜长均显著高于母羊(P<0.05);3月龄时公羊体高、体斜长和胸围均显著高于母羊(P<0.05);6月龄时母羊体重极显著高于公羊(P<0.01),成年时期公羊体重和体高均显著高于母羊(P<0.05);其余各生长阶段内,公母羊间体重及体尺差异不显著(P>0.05)。其成年时平均净毛率较低,为45.21%;长度适中:平均自然长度为4.55cm,伸直长度为6.22cm;细度良好,为17.60μm。公母羊血液生理生化指标及其同国内绵羊参考值相比存在一定的差异,其中母羊血小板总数(PLT)和血小板压积(PCT)均极显著高于公羊(P<0.01),公羊甘油三酯(TG)和白蛋白(ALB)含量显著高于母羊(P<0.05),其余各项指标均无显著差异(P>0.05)。综上所述,萨杜湖杂交羊在生长发育等方面都有不同程度的改进和提高,本试验结果可为该品种杂交羊进一步开发利用提供参考依据。  相似文献