仿洄游培育美洲鲥亲本的性腺发育

为解决美洲鲥(Alosa sapidissima)人工培育亲本性腺发育不佳的问题,开展了美洲鲥亲本仿洄游的培育,研究观察了美洲鲥亲本卵巢和精巢不同发育阶段(II^V期)的形态特征及相关参数,确定了仿洄游培育美洲鲥亲本性腺初次发育的特征。结果显示:在美洲鲥仿洄游培育过程中,在卵巢、精巢发育前期(II期),雌雄亲本生长迅速;而性腺发育到III期后,雌雄亲本的生长滞缓,雌鱼亲本甚至出现负生长。仿洄游培育美洲鲥性腺初次发育(II^V期)过程中,雌雄亲本均有较高的肥满度,分别为1.55~2.07和1.56~1.71;卵巢发育Ⅴ期雌鱼亲本的肥满度(2.07)显著高于在卵巢II^IV期亲本(1.55~1.67);而雄鱼亲本肥满度在精巢发育各阶段(II^V期)均无显著性差异。仿洄游培育美洲鲥性腺发育良好,雌雄亲本的性腺指数均较高,性腺发育Ⅴ期雌雄亲本的性腺指数(GSI)分别为(26.10±6.46)(18.88~33.62)和(5.18±0.68)(4.49~6.11)。研究表明,仿洄游培育的水温(10.8~30.8℃)和盐度(1~15)的周年变化符合美洲鲥亲本性腺发育的要求。     

美洲鲥帆布池塘大棚养殖试验

为探索池塘大棚养殖美洲鲥的可行性,采用GLP-832型标准蔬菜大棚、直径6 m的帆布池、黑白遮阳膜和通风控制系统等构建美洲鲥帆布池塘大棚养殖系统,利用河道水开展了美洲鲥养殖试验,通过自动温度记录仪每隔2h记录水温数据,并对该模式的养殖成本和效益进行了分析.结果表明,帆布池塘大棚养殖系统能够保持养殖池水温在9.9～30....     

工厂化养殖美洲鲥幼鱼的生长特性及消化酶活性变化

在工厂化养殖条件下,将初始体长为(54.04±6.07)mm、体质量为(2.03±0.75)g的4 000尾美洲鲥幼鱼放在有效体积约300 m³的养殖池中饲养84 d,研究美洲鲥幼鱼养殖过程中的生长特性及生长过程中消化酶活力的变化特点。结果显示:美洲鲥体长(L)、体质量(W)均与养殖时长(t)呈指数相关(L＝56.568e0.008 8t,W＝2.463 3e0.027 4t),体长与体质量呈幂函数相关(W＝7×10-6L3.158 2),试验期间美洲鲥幼鱼的生长类型为等速生长；总体上,肥满度随着幼鱼的生长发育而明显提高,试验初期(养殖14 d时)显著提高,之后有所降低,在42 d时显著下降(P＜0.05),之后幼鱼的肥满度保持着较快的增长,随着时间的推移显著提高(P＜0.05),并在试验结束时达到最高值。美洲鲥幼鱼胃蛋白酶活力随着幼鱼的生长显著升高(P＜0.05)；幽门盲囊的淀粉酶活力随着幼鱼生长显著下降(P＜0.05),而蛋白酶和脂肪酶活力总体呈升高趋势(P＜0.05)；肠道中淀粉酶的活力随着幼鱼生长而显著降低(P＜0.05),蛋白酶和脂肪酶活力总体呈上升趋势,最大值均出现在第84天(P＜0.05)。研究结果表明,工厂化养殖美洲鲥幼鱼的生长类型为等速生长,本试验的养殖条件适宜美洲鲥幼鱼生长；养殖过程中应根据消化酶的变化规律,适时调整饲料中营养成分的含量或添加生物酶制剂,以提高饲料的利用效率,提高养殖效益。     

美洲鲥工厂化养殖技术初探

为研究美洲鲥低能高效的温室工厂化养殖新技术,于2010年6月~2013年6月进行了温室工厂化养殖试验,同时探索了物联网技术在美洲鲥工厂化养殖生产中的应用。通过智能化管理,共生产美洲鲥商品鱼11084 kg,年平均单产10.14 kg/m2,年平均养殖效益达7353.69元/m2。     

美洲鲥亚成鱼池塘大棚越冬养殖试验

为弥补美洲鲥对水温耐受性较差的缺陷,使其在上海乃至江浙地区能自然过冬,2016-2019年通过在养殖池塘上搭建保温棚,开展了美洲鲥2龄鱼种越冬养殖试验。试验结果:2016-2017年、2017-2018年、2018-2019年3年越冬期间,美洲鲥的体长相对增长率分别为26.58%、5.63%、11.87%,体质量相对增长率分别为96.21%、27.46%、49.6%,养殖成活率分别为93.1%、70.5%、95.0%,饲料系数分别为2.36、3.51、2.21。结果表明,水温在12℃以上时,2龄美洲鲥摄食良好,越冬期仍然是其重要的生长期,在池塘上搭建越冬保温棚能够使美洲鲥安全过冬。建议在江浙沪等地区搭建越冬棚养殖美洲鲥,越冬放养密度控制在1000~1200尾/亩(15亩=1 hm^2,下同)。     

水库网箱美洲鲥养殖试验

<正>美洲鲥(Alosa sapidissima)属鲱形目,鲱科,鲥亚科,西鲱属,分布在北美洲大西洋西岸从加拿大魁北克省到美国的佛罗里达州河流和海洋中,与中国鲥(Tenualosa reevesii)同属一个亚科,是一种有较高营养和经济价值的溯河产卵洄游性鱼类[1,2]。由于目前中国鲥鱼资源的急剧减少,但人们对鲥鱼需求的热情不减,因此我国从2003年开始从美国引进美洲鲥,希望能够在中国驯养成功,以供市场之需。经过10年的驯化养殖摸索,美洲鲥的养殖水平不断提升,养殖成活率也得到一定的提高[3,4]。中国     

光照周期对美洲鲥生长及耗氧率的影响

为探究光照周期对美洲鲥生长及耗氧率的影响,在工厂化循环水养殖系统中,设置9L∶15D、12L∶12D、15L∶9D、24L∶0D(光L∶暗D)共4个光照周期处理组,开展为期60 d的试验,通过测算各组美洲鲥的摄食率、体质量增加率及成活率,研究光照周期对美洲鲥生长的影响,并采用封闭流水式呼吸装置,测定了上述4个光照周期条件下美洲鲥的24 h耗氧率。试验结果显示:随着光照时间的延长,摄食率和耗氧率均呈上升趋势,体质量增加率呈下降趋势,其中24L∶0D处理组摄食率和耗氧率显著高于9L∶15D处理组,体质量增加率显著低于9L∶15D处理组(P0.05)。试验期间各处理组美洲鲥的成活率没有显著差异。     

美洲鲥1+龄亚成鱼池塘越冬生长特性

为完善美洲鲥池塘养殖技术,对美洲鲥1~+龄亚成鱼在池塘保温大棚条件下越冬的生长特性进行了研究。在上海市水产研究所奉贤科研基地开展了美洲鲥池塘保温大棚越冬养殖试验,放养密度为4 682尾/hm~2。试验结果:在水温11.2~20.6℃条件下,经150 d的越冬养殖,越冬成活率98.0%,美洲鲥体长增长26.6%,体质量增加96.2%,体质量与体长呈幂函数关系:W=0.012 3L~(3.076),R~2=0.922 8,接近于匀速生长,体长、体质量日均增长量随养殖天数的增加呈n形变化,肥满度在1.55~1.71,最大值出现在越冬养殖中期。结果表明:美洲鲥1~+亚成鱼的适宜越冬水温在12℃以上,最佳越冬水温在15℃以上。     

美洲鲥的资源变动及修复

美洲鲥在美国渔业史上曾起到重要作用,但从19世纪初期开始,建闸筑坝、水域污染以及人们的过度捕捞,造成美洲鲥种群数量急剧下降,目前,美洲鲥在很多地区已经绝迹.然而,经过人们不断的努力,美洲鲥资源渐渐得到修复,每年在切萨皮克地区举行的鲥鱼节,让人们在庆祝这一自然文化财富的同时加深了对美洲鲥的了解.     

美洲鲥当年鱼种池塘遮阴养殖试验

为提高美洲鲥鱼种池塘遮阴养殖技术,采用推迟拉盖遮阴膜、提早拆除遮阴膜、适时搭建保温大棚等措施方法改进了美洲鲥当年鱼种池塘遮阴养殖方式,并开展了相关的养殖验证试验,研究比较了改进前、后的养殖效果。结果显示,2017年(改进前),美洲鲥当年鱼种经过120d的养殖,平均体长和体质量分别为12.46cm和26.53g,分别增长284.57%和3636.62%,肥满度为1.35g/cm~3,体长日增长率和体质量日增长率分别为0.076cm/d和0.215g/d,养殖成活率为81.02%,饲料系数为2.04;2018年(改进后),美洲鲥当年鱼种经过144d的养殖,体长和体质量分别为16.50～16.89cm和65.97～69.68g,分别增长293.70%～370.09%和6066.37%～9460.87%,肥满度为1.42～1.50g/cm~3,体长日增长率和体质量日增长率分别为0.088～0.090cm/d和0.453～0.476g/d,养殖成活率为75.94%～78.96%,饲料系数为1.63～1.77。试验结果表明,改进后的池塘遮阴养殖模式,其养殖效果好于单纯的遮阴池塘或露天池塘,与大水面网箱和深井水工厂化养殖模式相近。建议在江浙地区开展美洲鲥当年鱼种池塘养殖时,于放苗1周后拉盖遮阴膜,9月中旬移除遮阴膜,10月中旬搭建池塘保温大棚。     

美洲鲥的资源变动及修复

美洲鲥在美国渔业史上曾起到重要作用,但从19世纪初期开始,建闸筑坝、水域污染以及人们的过度捕捞,造成美洲鲥种群数量急剧下降,目前,美洲鲥在很多地区已经绝迹。然而,经过人们不断的努力,美洲鲥资源渐渐得到修复,每年在切萨皮克地区举行的鲥鱼节,让人们在庆祝这一自然文化财富的同时加深了对美洲鲥的了解。     

美洲鲥(Alosa sapidissima)的资源变动及修复

美洲鲥在美国渔业史上曾起到重要作用。然而从十九世纪初期开始，建闸筑坝、水域的污染以及人们的过度捕捞造成美洲鲥种群数量急剧下降，目前美洲鲥从很多地区已经绝迹。然而，经过人们不断的努力，美洲鲥资源渐渐得到修复，每年在切萨皮克地区举行的鲥鱼节，让人们在庆祝这一自然文化财富的同时加深了对美洲鲥的更多了解。     

From salmon to shad: Shifting sources of marine‐derived nutrients in the Columbia River Basin

Like Pacific salmon (Oncorhynchus spp.), nonnative American shad (Alosa sapidissima) have the potential to convey large quantities of nutrients between the Pacific Ocean and freshwater spawning areas in the Columbia River Basin (CRB). American shad are now the most numerous anadromous fish in the CRB, yet the magnitude of the resulting nutrient flux owing to the shift from salmon to shad is unknown. Nutrient flux models revealed that American shad conveyed over 15,000 kg of nitrogen (N) and 3,000 kg of phosphorus (P) annually to John Day Reservoir, the largest mainstem reservoir in the lower Columbia River. Shad were net importers of N, with juveniles and postspawners exporting just 31% of the N imported by adults. Shad were usually net importers of P, with juveniles and postspawners exporting 46% of the P imported by adults on average. American shad contributed <0.2% of the total annual P load into John Day Reservoir, but during June when most adult shad are migrating into John Day Reservoir, they contributed as much as 2.0% of the P load. Nutrient inputs by American shad were similar to current but far less than historical inputs of Pacific salmon owing to their smaller size. Given the relatively high background P levels and low retention times in lower Columbia River reservoirs, it is unlikely that shad marine‐derived nutrients affect nutrient balances or food web productivity through autotrophic pathways. However, a better understanding of shad spawning aggregations in the CRB is needed.     

Digestion of larval American shad by cyprinids

Cyprinids have pharyngeal teeth for grinding food before swallowing and a continuous gut with no discrete stomach. This digestive tract structure, as well as the feeding behavior traits shown by cyprinids, makes it difficult to identify and measure the amount of food consumed by these fishes. The relations among quantity of food in cyprinid gut, time after feeding and predator size were described by log-linear multiple regression. The number of intact American shad (Alosa sapidissima (Wilson)) larvae eaten in laboratory experiments was estimated by extrapolating the regression for the amount of food in the gut over time for predators of various size. The numbers of larval American shad in guts of fish captured in the Juniata River, Pennsylvania, were not significantly different from those estimated with the equations derived from laboratory data. In view of their abundance in rivers and their potential digestion rate for larval fish, cyprinids can be expected to have a marked influence on reducing the numbers of larval American shad.     

Predator response to releases of American shad larvae in the Susquehanna River basin

Abstract— Predation on American shad ( Alosa sapidissima ) larvae within the first two hours of release was examined from 1989 to 1992 on 31 occasions at stocking sites in the Susquehanna River basin. Twenty-two fish species consumed shad larvae; the dominant predators were spotfin shiner ( Cyprinella spiloptera ), mimic shiner ( Notropis volucellus ) and juvenile smallmouth bass ( Micropterus dolomieu ). The number of shad larvae found in predator stomachs ranged from 0 to 900. Mortality of shad larvae at the stocking site was usually less than 2%. The greatest mortality (9.6%) occurred at the highest stocking level (1.5 million larvae). Highly variable predation rates and release levels of shad insufficient to achieve predator satiation hindered the ability to determine a specific type of functional response of predators. Predator numbers increased with stocking density, indicating short-term aggregation at the release site. Because of practical problems associated with releasing the large numbers of larvae that would be required to satiate predators, routine stocking at these levels is probably unreasonable. Releases of 400,000 to 700,000 larvae may reduce predation by offsetting depensatory mechanisms that operate on small releases and the effects of increased predation due to predator aggregation on large releases. Night stocking may reduce predation on larval shad at the release site.     

人工生态条件下鲥鱼保种越冬的试验研究

在低盐度人工生态条件下鲥鱼保种越冬获得成功。在总密度为56.13尾/米~2(鲥鱼0.37尾、淡水白鲳55.76尾/米~2)的条件下,鲥幼鱼成活率达92.0％,3龄鱼达100％;在鲥鱼密度为8.99尾、淡水白鲳密度为7.80尾/米。的条件下,鲥幼鱼成活率达89.4％,3龄鱼达100％。试验表明,鲥鱼越冬期间可摄食人工饲料,无需投喂浮游生物;鲥鱼的商品化养殖越冬是可行的。     

美洲鲥鱼苗种规模化养殖技术研究--Ⅰ.稚鱼培育

用经过营养强化的卤虫作为开口饵料，采用配合饲料驯化养殖，水温控制在18=20℃，经30d培育，鲥鱼稚鱼规模化培育成活率达到74．6％，敏感期培育成活率达81．7％。稚鱼体质健壮，规格整齐，个体差异小，平均体长3.8cm，平均体重0.047g。     

Temperature,plankton and conspecific density influence dynamics of age‐0 gizzard shad: implications for a gape‐limited piscivore

Age‐0 gizzard shad Dorosoma cepedianum are the main prey fish for white crappies Pomoxis annularis in many US reservoirs. However, these prey fish commonly outgrow their vulnerability to white crappie predation in some, but not all, northern Missouri reservoirs. Potential variables that could influence abundance, growth and mortality of age‐0 gizzard shad were examined in three reservoirs that differed with respect to age‐0 gizzard shad growth rates. Because of thermal effluent from a power plant, gizzard shad spawned earlier in Thomas Hill Lake and initial densities of larvae were greater than in the other reservoirs. Larval and juvenile gizzard shad grew slowest in Thomas Hill Lake, followed by Mark Twain Lake and Long Branch Lake. Growth rate of larvae increased with increasing water temperature and food abundance, but decreased with increasing conspecific density. Similar relationships were found for juvenile growth, except that growth declined with increasing temperature. The slower growth of larvae and juveniles in Thomas Hill Lake was probably a consequence of their greater densities relative to their food abundance and higher water temperatures during the juvenile stage. Conversely, both larvae and juvenile gizzard shad grew more rapidly and juveniles attained large sizes in Long Branch Lake owing to their lower densities relative to their available food. Mortality of larvae and juveniles was mostly similar among the reservoirs. Because of their greater abundance and slower growth, gizzard shad were available as prey for white crappies for a longer period in Thomas Hill Lake than in the other reservoirs.     

人工诱导池养3+龄鲥鱼性腺发育的初步试验与探讨

通过模似鲥鱼性腺发育的自然生态条件和埋植 LHRH-A 和 Testosterone 缓释放颗粒激素,诱导池养3~+龄鲥鱼性腺发育季至第1期,成熟系数达0.9%。试验摸索出麻醉操作鲥鱼不死的有效方法。对今后鲥鱼全人工繁殖的前景及有关问题进行了探讨.     

Diel and seasonal changes in nutritional condition of the anadromous twaite shad Alosa fallax fallax (Lacépède, 1803) larvae

Abstract –  In this work we aim to study: (i) the diel and seasonal changes in nutritional condition, herein RNA/DNA ratios, of twaite shad ( Alosa fallax fallax ) larvae and (ii) the influence of environmental and biological covariates on those changes. Samples were collected in the River Mira (Portugal) from February 1998 to July 2000. The RNA/DNA ratios were significantly lower than average during dawn and dusk hours. This pattern can be attributed to: the absence of better-fit specimens escaping the net; a nightly increase in the RNA content in response to circadian rhythm; and/or nucleic acids of prey items remaining in the gut of larvae during daylight. Thus, the time of day is important when examining RNA/DNA ratios of twaite shad. Generalised additive model of seasonal data showed that water temperature, freshwater pulses and/or turbidity largely contribute to create adequate environments. These might enhance the nutritional condition of twaite shad larvae during the period that they remain in the upper reaches of River Mira.