Sectioned pelvic fin ray ageing of muskellunge Esox masquinongy from a Virginia river: comparisons among readers, with cleithrum estimates, and with tag–recapture growth data

Abstract  The potential utility of pelvic fin rays as ageing structures was evaluated for southern US muskellunge Esox masquinongy Mitchill populations by comparing age estimates among three readers and against cleithrum estimates, and by comparing observed length changes of tagged fish with changes predicted from growth equations based on pelvic fin ray age estimates. Mean coefficient of variation in age estimates among all readers and between the two readers with prior ageing experience was 17.8% and 5.6%, respectively. Exact and within 1-year agreement rates between pelvic fin rays and cleithra were 76% and 100%, respectively. Mean (± 2 SE) estimated absolute error between observed and predicted length changes for 13 tagged muskellunge was 30 ± 14 mm. This evaluation indicated that pelvic fin rays may prove to be a useful, non-lethal method for ageing muskellunge in southern US waters. Validation studies are still needed to ensure that growth rings form consistently throughout fish's life span.     

饲料企业降低沟通成本之浅见

在生产经营活动中．说到成本．人们大都会想到直接成本与间接成本．或生产成本与营销成本等有形成本．但有一类无形成本却往往容易被忽视，那就是沟通成本。沟通成本是指由于沟通不畅等原因造成的营运成本增加。由于其无形的特征．所以由它导致的成本上升很难用一个确切的数字来描述。我国饲料工业的历史不过20余年．即使是一些成功的饲料公司也难以通过根深蒂固的企业文化来规范员工的言行。加之缺乏诚信环境和市场不规范现象比比皆是．人员流动频繁，盈利导向至上，员工缺乏系统培训即上岗．唯亲是用等，这都或多或少导致了企业内部的信息与沟通不畅，甚至阻塞逆反．互相扯皮推诿，进而导致沟通成本上升，隐性费用增加，企业市场竞争力下降。     

棉籽粕营养成分最新调查

本介绍了对棉籽粕养分含量的最新调查结果，数据包括了平均值和变异范围。本应该对考虑在日粮中应用棉籽粕的营养师具有价值。     

恒河猴肾上腺皮质的显微与超微结构

应用光镜和透射电镜观察，恒河猴肾上腺皮质可分为球状带、束状带和网状带。其特点是：（1）被膜较发达，有时可伸入球状带将其细胞分隔为团块。（2）球状带有时呈指状指入束状带和网状带，其内可见嗜铬细胞；球状带细胞可分为明、暗2种类型，他们排列成团球状、滤泡状、索状和不规则形。（3）网状带较发达，有的可分为内、外2个区；有时网状带呈刺状伸入束状带；有时网状带细胞可见于被膜下或髓质内。（4）有时部分被膜连同皮质一起呈指状伸入髓质内。（5）皮质细胞均含丰富的溶酶体、线粒体和内质网，但不同部位的细胞所含的脂滴在数量、大小、形态和电子密度等方面存在差异。     

Nllegorie

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Neue Wege des Vogelschutzes im Obst-und Gartenbau

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