Diet composition of sturgeon fry (Acipenser persicus) reared in fertilized earthen ponds

Artificial rearing of fry has been introduced as an alternative to supply fry and juvenile sturgeon in order to restock the depleted sturgeon population in the Caspian Sea. The aim of this study is to assess the feed selection characteristics of sturgeon (Acipenser persicus) fry during the period in which they stay in earthen ponds before being released into the river. Sturgeon fry weighing around 150 mg were introduced into five almost similar‐sized earthen ponds. The ponds were enriched with fertilizer to supply natural food for the fries. A weekly sample of six specimens was collected from each pond during the 5 weeks of the experiment. All collected fish were weighed and then dissected for inspection of the stomach and the intestine content. The overall stomach content measured from 150 fish showed that around 74% of the stomach content was composed of chironomids and the rest was daphnia and cyclops. At the beginning of the study (first 2 weeks), sturgeon fry feed more on daphnia and cyclops; this trend, however, reversed in the last 2 weeks of the study. In conclusion, sturgeon fry feed on three prey groups—chironomids, daphnia and cyclops—during their lifespan in earthen pond. Feeding on chironomids larvae increased with sturgeon fry size.     

Evaluation of shrimp polyculture system in Thailand based on stable carbon and nitrogen isotope ratios

ABSTRACT: To quantify the contribution by cocultured animals to waste assimilation in an intensive shrimp farm in Thailand, the food web structures of the macrobenthos in a reservoir pond, a shrimp culture pond and water treatment ponds were examined using the stable C and N isotope ratio technique. Seawater for aquaculture was drawn from a creek, and stored in a reservoir pond, used for farming the banana prawn Fenneropenaeus merguiensis in culture ponds, and then recycled through treatment ponds where the green mussel Perna viridis was cultured to remove organic wastes discharged from the farming. The clam worm Nereididae sp. and the mud creeper Cerithideopsilla cingulata in the culture pond had δ ¹³C values of −21.0‰ and −18.4‰, respectively, suggesting that shrimp feed (mean δ ¹³C = −20.7‰) was the main food source for these species. The δ ¹³C analysis also suggested that sediments (−23.7‰) in the reservoir pond and particulate organic matter (POM) (−24.0‰) and/or sediments (−25.0‰) in the treatment pond supplied carbon for most macrobenthic animals. However, green mussels in the treatment pond had a mean δ ¹³C value of −20.5‰, suggesting that shrimp feed was the main food source for this species.     

淡水养殖中华鲟成鱼的3种方式及效果比较

淡水养殖中华鲟成鱼主要有工厂化养殖、网箱养殖和池塘养殖等3种方式。工厂化养殖和网箱养殖中华鲟成鱼的生长速度要明显快于池塘养殖方式,其中网箱养殖的成鱼有最大的相对生长率和瞬时生长率。工厂化养殖中华鲟成鱼需要较大的资金投入和较高的生产运行成本,同等生产规模的投资成本和生产运行成本为网箱养殖的2~3倍,不宜大规模推广,可选择条件适宜的山溪、水库进行自流式流水养殖;网箱养殖投入产出比高,能源消耗少,节约水资源,养殖中华鲟的生长速度、成活率、资金投入的效益等均有较明显的优势,是一种值得提倡和推广的中华鲟成鱼养殖方式。池塘养殖中华鲟成鱼虽然投入和成本低,但养殖成活率低,效果差,不宜大量采用。试验结果表明,工厂化养殖和网箱养殖中华鲟成鱼的单位面积载鱼量均较低,规格1~3kg的个体,养殖时的有效载鱼量控制在10kg·m-2左右较适宜,不宜超过15kg·m-2。     

海蜇—对虾—缢蛏—牙鲆综合养殖池塘的食物网分析

在面积6.7 hm^2,水深1.5～2.0 m的池塘中进行海蜇—中国明对虾—缢蛏—褐牙鲆综合养殖,在4—9月养殖周期内,采用碳氮稳定同位素法和IsoSource线性混合模型计算各种饵料对海蜇、中国明对虾、缢蛏和褐牙鲆的平均饵料贡献率,以探讨综合养殖池溏的营养级和池塘食物网结构。试验结果表明,海蜇的主要食物来源为投喂的轮虫;中国明对虾的食物来源为鳀鱼、虾夷扇贝下脚料和蜢虾;缢蛏的主要食物来源为底栖硅藻,其次为中国明对虾与褐牙鲆粪便;褐牙鲆的主要食物来源为中国明对虾,其次为虾夷扇贝下脚料和鳀鱼。海蜇的营养级为2.09～3.43,平均值为2.81;中国明对虾的营养级为3.11～4.04,平均值为3.72;缢蛏的营养级为2.37～2.94,平均值为2.62;褐牙鲆的营养级为2.63～3.83,平均值为3.42。综合分析发现,海蜇摄食浮游动物,缢蛏滤食底栖硅藻,中国明对虾和褐牙鲆摄食投喂的虾夷扇贝下脚料和鳀鱼,褐牙鲆也摄食部分中国明对虾,两者的粪便不仅为浮游单胞藻和底栖硅藻生长提供营养,还为缢蛏提供了饵料。上述研究结果为多品种海水综合养殖池塘的生态健康养殖提供科学依据。     

浙北地区利用冬闲虾塘饲养日本对虾的试验

利用饲养南美白对虾的冬闲虾塘 ,采取精养模式养一茬日本对虾 ,可提高围塘养殖的综合效益。本试验的放养密度为 2× 10 4余尾 / 6 6 7m2 ,单产 38.5kg/ 6 6 7m2 ,成活率 2 3.3%。盐度控制在 17以上     

塘养条件下硬壳蛤生长规律的研究

试验结果表明,4-5月和9-10月,水温22~27℃时,为硬壳蛤快速生长期;11月至翌年2月,水温8~15℃时,生长缓慢;5-6月硬壳蛤处于繁殖期间,生长也较为缓慢。硬壳蛤壳长和壳高的相关关系为y=1.8479x 0.5923;壳长和体质量的相关关系为y=0.0002x3.1174。     

池塘养殖尾水经稻田生态工程净化后的浮游细菌群落特征

为利用稻田生态工程对精养池塘尾水进行循环利用,采用Illumina Mi Seq第二代测序技术比较分析了稻田生态工程进出水中浮游细菌群落结构和多样性差异,以探讨稻田生态工程净化回用水中浮游细菌群落变化对池塘养殖的影响。结果显示,稻田生态工程进出水中优势浮游细菌在门水平上的组成相同,均为蓝细菌门(Cyanobacteria)、变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)和拟杆菌门(Bacteroidetes)。但优势门类的相对丰度发生变化,蓝细菌门的相对丰度由进水中的46.72%显著降低至表面流出水中的41.82%和渗流出水中的34.77%;而放线菌门的相对丰度由3.90%增加至表面流出水中的5.65%和渗流出水中的6.45%。属水平上优势浮游细菌组成也相同,但微囊藻属(Microcystis)的相对丰度由0.83%显著降低至渗流出水中的0.46%(P0.05)。另外,稻田生态工程表面流出水中浮游细菌物种丰富度指数(Chao 1)显著提高,渗流出水中Shannon多样性指数显著提高,且Simpson指数显著降低(P0.05)。     

混养海湾扇贝对刺参池塘养殖环境的影响

为建立参贝混养的生态养殖模式,研究了海湾扇贝在池塘中与刺参混养,对养殖环境的影响。通过参贝混养与海参单养池的比较研究表明:参贝混养池的水质指标:氨态氮、亚硝酸盐等明显低于海参单养池;扇贝的滤食作用改善了水的透明度,参贝混养池明显高于海参单养池。参贝混养池中浮游生物的种类和数量优于单养池,海参喜食的底栖硅藻的生物量较多;浮游动物的种类较少,规格也较小。为池塘参贝生态养殖提供了参考依据。     

方斑东风螺池塘养殖试验

在0.16 hm2的土池中,9月投放壳高1.30~2.61 cm、体重0.90~2.68 g的方斑东风螺稚螺5.41万粒,经4个月的试养,育成商品螺243.0 kg,个体重2.5~12.0 g,平均体重5.25 g;壳高2.53~4.35 cm,平均3.05 cm;成活率86.3%,饵料系数2.3,获产值28 188元。经试验方斑东风螺对养殖环境海水水质的适应能力较强,对水温的适应范围较广,是一种优良的海水养殖品种,适合南方池塘养殖。     

虾池水环境因子与虾病爆发的相关性分析

2001～2002年在对瓦房店市和庄河市等虾池水环境因子的连续监测中,运用多元分析研究了水环境因子与对虾病害爆发的相关性,主成分分析结果表明,NO3-N、COD、NO2-N、盐度、NH3-N和水温是显示对虾疾病爆发的关键因子。