观赏鱼和水族生态地图鱼的饲养与繁殖

地图鱼(Astronotus ocellatus)又称猪仔鱼、花猪、血红猪、红猪、黑猪鱼、星丽鱼、尾星鱼等.在分类上隶属于鲈形目、丽鱼科.原产于南美亚马逊河上游、巴拉圭、圭亚那、委内瑞拉境内,现已引入我国.     

瘦肉猪高产仔母系培育及其配套利用研究报告(二)

3母系猪的特征特性及生产性能3.1品系特征特性3.1.1体型外貌:弱系猪全身被毛白色(占98.57%),偶有黑、花猪(占1.43%);嘴筒直、中等长;耳中等大、稍下垂;头清秀,中等大小;体躯中等长,成年体重公猪(135.00±5.36)kg、母猪(116.00±5.98)kg,成年个体体长公猪(136.10±6.04)cm、母猪(132.17±6.15)cm;背腰平直,腿臀丰满,四肢较高而结实;有效奶头7对半以上。3.1.2适应性:母系猪因含梅山猪血缘50%,因此其对许多地区的气候、环境都比较适应,特别是在江南温湿气候里,其生长、发情、产仔、成活都很正常。在巴南区许多农户示范推广,均认为母系猪的发情…     

怎样选择畜禽风机

<正>夏季畜禽舍降温目前普遍采用"风机+湿帘"的降温形式。可相当一部分养殖人员,特别是养殖场场长或老板,不懂得夏季畜禽舍降温的原理。花冤枉钱,没养好鸡(或猪),究其原因:不会选择纵向大风机,没有达到预期     

猪水肿病的诊断与防治

<正>猪水肿病又称大肠杆菌毒血症、浮肿病、胃水肿,是仔猪一种急性、致死性疾病,该病发病突然,致死率高。最近一段时间花岗区一些养猪场发生了仔猪水肿病,给养猪场带来了很大的损失。1流行病学本病主要发生于断乳仔猪,小至数日龄,大至4月龄都有发生。     

泰山地方猪不同杂交组合生产试验

泰山地方猪是主要分布于山东泰安地区的地方猪种,为促进其资源保护和开发利用,对以泰山地方猪为母本的长泰二元杂交组合和杜长泰、大长泰三元杂交组合进行了生产试验测定。结果长泰组合平均窝产活子148.头,杂交猪60～210日龄肥育期日增重517g;杜长泰、大长泰三元杂交组合平均窝产活子分别为117.头和118.头,杂交猪平均育肥日增重为577 g和584g,二者差异不显著。大长泰三元杂交猪均为纯白毛色,杜长泰杂交猪出现白、黑、花等不同的毛色分离。与同期饲养的杜长大“洋三元”杂交猪相比,杜长泰、大长泰杂交猪肥育性能略低,但母猪繁育性能好,产仔多,仔猪生长快,成活率高,耐粗饲。适于在管理较粗放的中小型猪场和农户饲养推广。     

安徽名贵水产拾零

歙州山鳗多产于皖南山区溪潭中,而以歙县山鳗著称。明代李时珍《本草纲目、鳞部》鳗鲡集解:“歙州(今歙县)溪潭中出一种背有五色文者,头似蝮蛇,入药最佳。江河难得五色者。”今考,歙州山鳗即花鳗,为鳗鲡目鳗鲡科。固其长年生活在深山溪潭中,环境特殊,其色泽已非同于常见的河鳗。其肉细嫩,《本草》云:“食之能补虚损,及久病痨瘵(zhai)。”至今,皖南山区的群众仍视其为病后之补品。     

地图鱼的饲养与繁殖

地图鱼(Astronotus ocellatus)又称猪仔鱼、花猪、血红猪、红猪、黑猪鱼、星丽鱼、尾星鱼等。在分类上隶属于鲈形目、丽鱼科。原产于南美亚马逊河上游、巴拉圭、圭亚那、委内瑞拉境内,现已引入我国。地图鱼是一种既可食用,又可观赏的大型热带鱼类,在原产地是作为食用鱼而加以饲养的,该鱼可在池塘中饲养,也可在网箱中饲养,但是在我国主要是作为一种高档的观赏鱼类来饲养的,鱼友大多在水族箱中饲养,少部分在小型池塘中饲养。由于它具有个体大、能与人亲善的优点,使饲养者有一种巨大的成功感,因此在我国倍受人们的青睐,尤其是在大中城市具有广…     

扁弯口吸虫病的发生及防治

地图鱼(Astronotus ocellatus)别名猪仔鱼、星丽鱼、黑猪鱼、花猪鱼,隶属于慈鲷科,原产地圭亚那、委内瑞拉、巴西等国。地图鱼体型魁梧,宽厚,鱼体呈椭圆形,体高而侧扁,尾鳍扇形,口大,基本体色是黑色、黄褐色或青黑色,体侧有不规则的橙黄色斑块和红色条纹,形似地图,因而得名。成熟的鱼尾柄部出现带红黄色边缘的大黑点,状如眼睛,可作保护色及诱     

浙江省内最大异地养猪场建成

中国养殖网消息：2007年年底，宁波市民将能从餐桌上吃到听着轻音乐吃着牧草长大的猪肉。4月10日，记者从宁波市贸易局获悉，一个年产10万头优质肉猪的大型畜牧基地，已经在浙西的衢州市衢江区莲花镇建成，并于下月投产。这是宁波市贸易局为了缓解市区生猪供需紧张而异地创办的畜牧基地。这也是浙江省内最大的异地养猪场。据牧场投资人秦建定介绍，为了饲养优质肉猪，牧场花了10多万元购置全套音响设备，在每幢猪舍安装两只播音设备，每天定时为猪们播放轻音乐。“让猪们也享受音乐的美妙，放松放松，有利于促进健康生长。”     

当前猪病新特点

<正>猪气喘病可以左右很多疾病的病情,例如:猪气喘病常并发猪传染性胸膜肺炎、猪肺疫、副猪嗜血杆菌感染。猪蓝耳病常与以下疾病继发感染:猪链球菌病、副猪嗜血杆菌感染、猪附红细胞体病、猪副伤寒、猪巴氏杆菌病。猪圆环病毒II型感染长与下列疾病继发感染:副猪嗜血杆菌感染、猪巴     

东海区拖网网囊网目选择性研究

通过东海区拖网网囊网目对带鱼和小黄鱼的选择性试验，对拖网最适网囊网目尺寸进行了分析研究。结果表明：1．网囊网目45mm，小黄鱼和带鱼的逃逸率均较低，渔获中兼捕大量当年生经济幼鱼；2．网囊网目54mm，小黄鱼的50％选择体长尚小于其优势体长组范围，带鱼的50％，选择体长已部分进入其优势体长组范围；3．网囊网目65mm，选择体长范围与选择鱼种的优势体长组范围基本一致。综合分析认为：目前东海区最理想的拖网网囊网目不小于60mm。     

黄海南部不同体长鳀对食物粒级的选择

基于2000年6月和2014年11月黄海南部采集的浮游动物和不同生长阶段鳀(Engraulis japonicus)的胃含物(饵料)组成分析资料,研究鳀的饵料粒级分布与摄食粒级选择性及其与环境生物组成的关系,旨在推进粒级在传统摄食生态分析中的应用。结果显示:黄海南部鳀的饵料种类组成与环境中生物种类组成有关;各体长组中,鳀的饵料粒级多样性与种类多样性分布趋势相似;体长为110 mm左右的鳀的饵料种类多样性和粒级多样性水平最高;鳀的饵料粒级均值随鱼体体长增加而增加;体长约为30 mm和≥70 mm的鳀有明显的饵料粒级转换。根据上述结果,认为在鳀胃含物分析过程中,整合环境中饵料生物的相对组成和粒级大小,可有效评价鱼类对饵料的粒级选择性。     

浙江南部近海鱼类粒径谱特征

为了解浙江南部近海鱼类群落粒径结构的时空特征、季节变动及其影响因素,基于2019年4个季节的渔业资源调查数据,利用粒径谱、多维尺度排序等方法,研究了鱼类粒径谱特征及其时空变动.结果表明,全年Sheldon鱼类粒径谱形状大体为单峰型,鱼类粒级介于?2～11,最高值出现在6～7粒级,以小型鱼类为主.四季Sheldon鱼类粒...     

多囊桁拖网选择性研究中对照网囊网目尺寸的选择

对比作业法是拖网渔具选择性研究中重要的试验方法之一,而对比试验中对照网囊网目的选择至关重要。研究利用多囊桁拖网不同网目尺寸(20、30、35和40mm)网囊捕获的哈氏仿对虾、小黄鱼和棘头梅童鱼渔获体长分布数据,应用几何相似原理,分析过滤性渔具的选择性,并按不同假设条件下(假设1:符合几何相似原理对渔获具有一定的选择性;假设2:对渔获种类没有选择性),探讨如何合理选择对照网囊网目尺寸。结果表明,对照网网囊网目尺寸为20mm,在上述2种假设下,对选择性模型的拟合、简化及对其它网囊的选择性参数没有显著的影响;在考虑了桁拖网渔具各网囊具有相同相对作业强度,以及桁拖网渔具与普通拖网渔具选择性分析方法上的差异等因素后,认为在此项研究中,将小于20mm网目尺寸的网囊视为没有选择性的对照网囊是可行的。     

Optimal harvesting of farmed Atlantic salmon at two cohort management strategies and different harvest operation restrictions

Abstract

The main harvest planning problem in commercial fish farms is to determine the best time‐sequence of harvesting different fish cohorts in order to maximize the overall farm profit. Due to both annual and fish‐size variations in market prices, future forecasts of fish growth and size distribution are required to optimize harvest plans. Two management strategies for harvesting size‐structured fish cohorts are considered. The first strategy allows the fish farmer, at any time, to size‐grade, harvest and sell the most profitable fish sizes from the standing stock. The second strategy allows the fish farmer to harvest and sell a fish batch with similar size distribution as that of the standing stock. In this paper, two size‐structured fish growth models have been built to fit the two management strategies. The growth models are integrated in a multiperiod linear programming model that optimizes the harvest outputs for each of the two management strategies. Model outputs demonstrate clearly that it is more profitable to size‐grade fish prior to harvest compared to harvesting a batch of fish with similar size distribution to that of the standing stock. Five different harvest operations constraints have been identified for commercial salmon farming. The decrease in profitability of fish farming is shown for a variety of harvest operation constraints.     

Seasonal and interannual components of intrapopulation variation in clutch size and egg size of a darter

Abstract –  Previous studies have offered suggestive but sometimes conflicting glimpses at the range and patterns of seasonal and interannual variation in female darter life-history traits. The present study examined clutch-size and egg-size variation from a single Mississippi population of brighteye darters (Etheostoma lynceum ), collected at regular intervals over four sequential spawning seasons. Both life-history traits were significantly correlated with body size, and they both showed significant variation within and among breeding seasons. The overall intraseasonal trends in these traits involved an increase in clutch size (CS) and a decrease in egg size from early to late periods of the spawning season. Clutch size and egg size showed a weak but significant negative correlation, which was indicative of a trade-off between the two clutch parameters. Seasonal changes in temperature appear to be related to differing patterns of seasonal variation in egg size reported in the literature for darters. Inverse seasonal shifts in egg size and CS in the brighteye darter may represent adaptive phenotypic plasticity that allows females to produce larger, competitively superior offspring early in the reproductive season when there is low supply of food for them (parental investment hypothesis) or to produce larger eggs early in the reproductive season to ensure that each egg is adequately provisioned in the face of uncertainty (bet-hedging hypothesis) if the food available for the young is unpredictable early in the season. Consistent with theoretical predictions, egg size showed less phenotypic variability than CS.     

A genetics analysis of the performance of three rainbow trout broodstocks

The reproductive performance of three domesticated rainbow trout broodstocks spawning at 2 years of age was analysed using data collected over a period of 5 years. Data were collected for post-spawning body weight, volume of eggs spawned, egg size, egg number and fertility to the eyed egg stage. There were significant differences among the stocks attributable to both genetic and environmental causes. In addition, there were marked differences between year-classes, isolated from each other due to 2-year spawning. The differences appeared to be genetic in origin and demonstrated the effect of sampling the original parents.Heritabilities estimated from full-sib comparisons indicated male weight was more influenced by environmental stress at spawning than was female weight. Heritability estimates for egg volume, egg size and egg number ranged from 0.05 to 0.76 for individual stocks, but when averaged for the three stocks the range was from 0.32 to 0.52. Egg size was found to have the lowest heritability of the three traits. The heritability of fertility was found to be low and was the lowest for the stock with the poorest fertility.Genetic and phenotype correlations among the traits were also estimated. The relationship between body weight and egg volume and size were both positive as was that between egg volume and egg size. It was determined that egg volume was the principal determinant of egg number and that the relationship of number to size could be negative. The latter evidence was obtained by artificially adjusting the egg production traits to a constant female body size. The result suggested that females that produce larger numbers of eggs are likely to produce smaller eggs unless the change is associated with a marked increase in body weight. It is recommended that selection for egg size be included in all selection programs and that egg number be ignored in any selection program designed to increase body size.     

Can timing of spawning explain the increase in egg size with female size in salmonid fish?

A common observation is that egg size increases with maternal size within populations. Several hypotheses have been proposed to explain this phenomenon. Most recently, it was suggested that the optimal egg size depends on female size due to correlations between (i) breeding time and egg size selection and (ii) female size and breeding time, and as such, the positive egg size–maternal size relationship represents an adaptive strategy. Here, we test the second of these two premises in two salmonid species, Atlantic salmon (Salmo salar) and coho salmon (Oncorhynchus kisutch) for which we have detailed breeding and egg size data. The body size of spawning females decreased throughout the season in coho salmon, but not in Atlantic salmon. Furthermore, we did not find a direct correlation between egg size and breeding time, which would also be expected if this premise was correct. Accordingly, breeding date does not appear to be as important as other factors in shaping among female differences in egg size.     

Egg size differentiation among sympatric demes of brown trout: possible effects of density-dependent interactions among fry

Abstract –  This study investigates differentiation in egg size among five sympatric brown trout ( Salmo trutta (L.)) demes. We explore a hypothesis predicting high density-dependent interactions among juveniles to favour large eggs by sampling closely located (<100 m) deme pairs with low and high fry abundances. A mancova model fitted the egg size versus egg number relationship as a function of large-scale spatial habitat heterogeneity (basin) and maternal phenotype revealed that demes have significantly different egg size versus fecundity relationships and that the differentiation is mainly due to interdeme variation in egg size. Fry density was significantly and positively associated with egg size and a post-hoc test indicated egg size to be significantly greater in high-density than low-density tributaries. The data is consistent with the density-dependent hypothesis and suggest that reproductive investment can diverge over small geographic distances, potentially in response to environments favouring greater investment in offspring quality.     

Relationship between body length, processed-meat length and seasonal change in net processed-meat yield of Japanese mantis shrimp Oratosquilla oratoria in Tokyo Bay

ABSTRACT:   There is concern regarding a possible decrease in the minimum exploitable size of the mantis shrimp Oratosquilla oratoria in Tokyo Bay, coincident with a decline in stock size. To assess this problem, the condition factor, the relationship between body length and processed-meat length, and the estimated body length for each market size category were investigated and compared monthly. The condition factor was lowest in spring and peaked in winter. The difference between body length and meat length was higher in summer and winter than in spring and autumn, suggesting that a high condition factor does not result in an increased net yield of processed meat. The annual mean minimum exploitable size in the present low-stock-size condition did not differ from the minimum exploitable size measured during a high-stock-size period (11-cm body length). However, the minimum exploitable size changed seasonally, which coincided with seasonal change in the net processed-meat yield. Exploitation during the season when net meat yield is high would result in increase of the large-sized meat products of high price.