南美白对虾与河蟹的池塘混养试验

面积均为0．4hm^2的试验池塘4口，每口池塘放养蟹苗8500只、南美自对虾苗5万～15万尾、鲢鳙老口苗60尾；饲养120d，总产值150547元，总利润80719元。投入产出比为l：2．2；虾蟹池塘混养。蟹种放养规格以160只／kg、虾苗以5万～lO万尾／hm^2较为适宜。     

藕塘养殖鲶鱼生态试验

池塘面积4hm^2，栽种鄂莲4号浅水莲藕种3750kg／hm^2，投放50尾／kg的鲶鱼种7500尾／hm^2、草鱼夏花2万尾；共收获白莲藕90000kg、鱼4500kg，毛收入10．45万元，纯收入4．65万元，投入产出比为1：1．8；为当地调整养殖品种结构探索了一种新模式。     

三疣梭子蟹与不同虾类混养技术研究

分别利用中国明对虾、凡纳滨对虾、日本囊对虾和脊尾白虾等虾类与三疣梭子蟹进行混养。结果表明:日本囊对虾与三疣梭子蟹混养组三疣梭子蟹养殖单产最高,平均产量1678.5 kg/hm2,其次为凡纳滨对虾与三疣梭子蟹混养组,平均产量1659 kg/hm2。对虾养殖单产以凡纳滨对虾与三疣梭子蟹混养组最高,平均产量990 kg/hm2,其次为中国明对虾与三疣梭子蟹混养组,平均产量952.5 kg/hm2。但考虑到日本囊对虾市场售价为其他混养虾类的两倍,因而日本囊对虾与三疣梭子蟹混养组养殖效益最高。     

石庄水库滩涂筑坝养蟹技术总结

筑坝围塘5．33hm^2进行河蟹养殖，投放规格6g／只的蟹苗2．7万只，养殖5个月，起捕成蟹1329kg，平均规格132g／只，回捕率36．8％，单产249kg／hm^2，总收入28．78万元，纯收入12．00万元，折合纯收入2．25万元／hm^2，投入产出比1：1．7。     

大弹涂鱼池塘养殖试验

在面积为2．5hm^2和1．1hm^2的2个池塘进行大弹涂鱼养殖试验。1998年4月放养4．2－6．3g鱼苗，共14．7万尾，1999年4月放养3．9－5．5g鱼苗共14．6万尾，经过精心管理，至收获时体重14－18g商品鱼分别为3536kg,3592kg。平均产量927－1027．5kg／hm^2，成活率达79．8－81．5％，投入产出比1：1．9－2．0，效果良好。     

投喂蝇蛆混养中国明对虾和三疣梭子蟹试验

利用2口1.5 hm2的池塘进行投喂蝇蛆混养中国明对虾和三疣梭子蟹试验,1﹟池不投喂蝇蛆,2﹟池配合投喂30%～50%蝇蛆.试验结果表明,2﹟池对虾、梭子蟹产量分别是1﹟池的1.8倍和1.2倍,成活率分别比1﹟池高10.7%和2.7%;纯利润2﹟池比1﹟池多2.8万元;投入产出比,1﹟池为1∶2.73,2﹟池为1∶3.19.2﹟池虾蟹体质量同期增长高于1﹟池,这一变化在养殖中后期更为显著.投喂30%～50%鲜活蝇蛆混养中国明对虾及三疣梭子蟹效益显著.     

池塘循环海水高效养虾试验

池塘循环海水高效养虾技术是一种集约化养殖模式。本试验以南美白对虾为饲养对象，经4个月（6-9月）管理，对虾产量为12000-14700kg/hm^2，出池规格达13.23-17.07g/尾，成活率80%-90%，纯收入84300-115200元/hm^2，投入产出比为1：1.6-1:2.5。     

沿河滩地渔业综合开发的经济效益分析

河滩面积4．84hm^2，采用立体综合养殖模式；总投入61．43万元，总收入87．22万元，净收入25．79万元，单位面积纯收入5．32万元／hm^2，投入产出比为1：1．41。     

无棣对虾养殖产量产值创历史新高

无棣县拥有浅海滩涂面积10万hm^2（150万亩1，发展渔业养殖具有得天独厚的自然优势。今年以来，无棣县海洋与渔业局通过大力实施省渔业科技人户示范工程，利用“一水多用”现代循环渔业养殖技术，主推对虾与缢蛏、对虾与杂色蛤、对虾与梭子蟹等生态立体混养模式，进行了对虾规模化养殖开发，对虾养殖发展到2．3万hm^2（34．9万亩），实现产量12450t、产值3．11亿元，产量和产值均创历史新高。     

中小型养鱼湖泊河蟹增养殖试验初探

2000年在沅江市小黄家湖（面积116hm^2)常规鱼放养品种、规格、密度与1999年相同的基础上，增放长江蟹种174kg，87000只进行对比试验。结果：湖泊产量、产值、利润、投入产出比分别由1999年的166344kg,656444元，267960元，1：1.69提高到2000年的174023kg,797268元，347304元，1．77，其中河蟹产量、产值、利润、投入产出比依次为2691kg,161460元，88856元，1：2．22。河蟹产量虽只占湖泊总产量的1．5％，但产值、利润分别占总产值和总利润的20．3％和25．6％。     

Food and feeding habits of Tilapia zillii (Gervais) (Cichlidae) in Lake Kinneret (Israel)

Analysis of the gut content of 329 specimens of T. zillii (Cichlidae) collected from Lake Kinneret, has shown great variation in the sorts of food.A study of seasonal dynamics has proved the prevalence in the food of Chironomida pupae (Diptera) in winter and spring and of zooplankton forms in summer and autumn. The additional food consisted of the various groups of algae, the most frequently found being Cyanophyta (100%) and Pyrrophyta (64.16%). An extremely voraceous species, it consumes — while searching for its preferred food — anything that comes its way in the water: algae, scraps of macrophytes, autochthonous and allochthonous insects, and forms of benthic origin, such as Nematoda, Ostracoda, Porifera and Chironomida (larvae).The satiation index is high (between 4.08 and 5.63), in contradiction to the low values of the coefficient of condition (between 3.05 and 3.51), and with the slow rate of growth in Lake Kinneret. The main food of Tilapia zillii, consists of arthropod species with a chitin content (which is eliminated unchanged) of more than 50% of the total weight, and this may account for the poor exploitation of the trophic base.This species of fish may be considered as being detrimental to others (i.e. commercially important species) because of its successful competition for food, and not, as is often incorrectly assumed, because it is an aggressive consumer of their spawn and fry.     

Food and feeding habits of Tilapia aurea (Steindachner) (Cichlidae) in Lake Kinneret (Israel)

An analysis of the food of 274 specimens of Tilapia aurea (Steindachner), which had been collected in Lake Kinneret, showed that this species is mainly a zooplankton consumer.A study of the quantitative dynamics of the food components in the course of a year has proved that the species in question feeds more intensely in spring, this being the time when zooplankton forms are more abundant in the water of the lake. Vegetable detritus, mixed with plankton and benthos forms, served as additional and alternative food.The lack of clearly positive degree of food component selectivity, as well as the low values of the intestine repletion index and of the condition coefficient, account for the slowness in growth of Tilapia aurea in Lake Kinneret.The low values of the growth and feeding indices are due, according to the authors, to the pressure brought to bear by the other local fish species, which are competitors for the same food.     

不同品系尼罗罗非鱼致死低温的研究

在室内自然降温条件下，研究了三个品系尼罗罗非鱼（吉富品系，“７８”品系，“８８”品系）对低温的耐受力，计算得出每个品系的半致死低温，并对降温过程中尼罗罗非鱼行为活动的变化进行了观察。试验结果表明，在上海地区，当温度降低到１１℃时，罗非鱼开始死亡，到７．４℃时，全部死亡。吉富罗非鱼死亡温度范围是１１℃￣８．４℃，“７８”品系是９．８￣７．４℃，“８８”品系是１１℃￣７．４℃。对三个品系半致死低温的研     

叶尔羌高原鳅胚胎发育与胚后发育观察

采用形态学和生态学方法,对叶尔羌高原鳅[Triplophysa(Hedinichthys)yarkandensis(Day)]胚胎发育和胚后发育阶段全过程进行观察、拍照并测量。结果显示:叶尔羌高原鳅,卵微黏性,略有沉性,受精卵呈卵圆形,卵径为(0.60±0.052)mm,在水温(20.0±1.0)℃下,历时65 h 34 min完成整个胚胎发育分为7个生理阶段过程;胚后发育主要根据卵黄囊、体色、鼓鳔和须的变化分为仔鱼期、稚鱼期、幼鱼期。初孵卵黄囊仔鱼全长(2.0±0.65)mm,出膜后7 d,卵黄囊吸收完毕,完全消失;初孵仔鱼继续培育至16日龄,仔鱼鳃盖后缘鼓鳔明显长出,须清晰可辨,体色加深,心脏红色素明显,体色与成体相似,标志后期仔鱼发育完全进入稚鱼期,此时鱼苗全长(8.0±0.45)mm;培育至30日龄,仔鱼鼓鳔完全,鳃盖张合明显,身体透明特征消失,稚鱼阶段完成发育进入幼鱼期,此时全长达(13.0±0.55)mm,其外部形态和生态习性均与成鱼相似。试验中,卵黄囊长度(LY)和出膜天数(D)的关系式:LY=0.0286D2–0.0636D+3.1196(R2=0.9050);用直线方程拟合卵黄囊长度(LY)和卵黄囊仔鱼全长(LT)的关系式:LY=–1.315LT+5.368(R2=0.8199);拟合卵黄囊仔鱼全长(LT)和出膜后仔稚鱼天数(D)的关系式:LT=–0.0263D2+0.5113D+1.6169(R2=0.9890)。本研究旨在通过了解叶尔羌高原鳅的早期发育特征为该物种的保护和增殖对策提供科学依据,并对其苗种生产提供理论指导。     

Grass carp (Ctenopharyngodon idella) grazing on duckweed (Spirodela polyrhiza)

The aims of this experiment were (1) toquantify the ability of grass carp to processduckweed and (2) to assess indirect changes inwater chemistry and phytoplankton community,caused by grass carp feeding. Yearling grass carp sized 126 ± 7.7 mm (TL) and19.6 g in weight were kept in 9 laminate tanksof 1 m³ for 14 days. Two stockingdensities (2 and 6 fish per m³) anda control without fish were used. Standard growthrate (SGR) of grass carp fed exclusively onduckweed was 0.70% body weight (BW) d^–1and food conversion ratio (FCR) reached 2.0(average water temperature =21.1 ± 3.8 °C). Daily food intakewas 0.2 g of duckweed dry weight (DW), i.e.,1% of average BW of grass carp. SGR ofduckweed growing in 20 × 20 cm floatingenclosures, differed significantly[F(6,2) = 417.9; p = 0.002] between the twostocking densities of grass carp and thecontrol tanks (without fish). Mean SGR ofduckweed was 0.02 g g^–1 day^–1 and thehighest SGR was recorded in the control tanks.Both decrease in NH₄-N and increase inNO₂-N concentrations differedsignificantly between the treatments[F(2,2) = 45.3; p = 0.02 and F(2,2) = 19.2; p = 0.04 respectively]. Changes in other nitrogenand phosphorus components (NO₃-N, TN, TPand PO₄-P) caused by stocking of grasscarp were not significant. Biomass ofphytoplankton, dominated by filamentous algaeand blue-greens, increased proportionately tostocking density of grass carp. Althoughduckweed has a large potential for nutrientremoval, the most common pathway for thenutrients released through grass carp grazingif duckweed cover is loose is theirincorporation into phytoplankton biomass.     

Development of embryos in Mastacembelus mastacembelus (Bank & Solender, 1794) (Mesopotamian spiny eel) (Mastacembelidae)

In this study, the embryonic development of the eggs in the Mastacembelus mastacembelus (Bank & Solender, 1794) was examined. At the same time, possibilities of artificial breeding through artificial insemination were investigated. Artificial insemination was achieved by mixing the eggs of the mature female and sperm of the mature male samples caught with gill nets (22 × 22) in Ataturk Dam Lake in Turkey. To this end, first in a Petri dish (100 × 20), the testes were cut into small pieces with a lancet and the mixture of sperm–testes‐tissue was obtained. The fertilization rate of the eggs was found to be 80%. The diameter of the eggs ranged from 2.015to 1.147 mm. The perivitelline space formed 0.5 h after insemination. The first cleavage occurred at the animal pool 4 h after insemination. The oil droplets had fused to a single droplet 19 h after insemination. The blastoderm became an embryonic shield 30 h after insemination. The blastoderm covered almost half the egg 40 h after insemination and embryonic body was formed. The blastoderm covered almost the whole egg 50 h after insemination. Some somites were discernible 59 h after insemination. The embryonic body reached two‐third of the circumference of the egg 70 h after insemination. The tail bud began to separate from the yolk 77 h after insemination. A newly hatched larva was observed at 85 h after insemination.     

Transmission of white spot syndrome virus (WSSV) from Dendronereis spp. (Peters) (Nereididae) to penaeid shrimp

Dendronereis spp. (Peters) (Nereididae) is a common polychaete in shrimp ponds built on intertidal land and is natural food for shrimp in traditionally managed ponds in Indonesia. White spot syndrome virus (WSSV), an important viral pathogen of the shrimp, can replicate in this polychaete (Desrina et al. 2013); therefore, it is a potential propagative vector for virus transmission. The major aim of this study was to determine whether WSSV can be transmitted from naturally infected Dendronereis spp. to specific pathogen‐free (SPF) Pacific white shrimp Litopenaeus vannamei (Boone) through feeding. WSSV was detected in naturally infected Dendronereis spp. and Penaeus monodon Fabricius from a traditional shrimp pond, and the positive animals were used in the current experiment. WSSV‐infected Dendronereis spp. and P. monodon in a pond had a point prevalence of 90% and 80%, respectively, as measured by PCR. WSSV was detected in the head, gills, blood and mid‐body of Dendronereis spp. WSSV from naturally infected Dendronereis spp was transmitted to SPF L. vannamei and subsequently from this shrimp to new naïve‐SPF L. vannamei to cause transient infection. Our findings support the contention that Dendronereis spp, upon feeding, can be a source of WSSV infection of shrimp in ponds.     

Extinction of Daphnia lumholtzi (Sars) in Lake Kinneret (Israel)

Daphnia lumholtzi (Sars) was found in Lake Kinneret until the late nineteen-fifties. Lake Kinneret was the northern-most limit of the distribution of this species. It is suggested that fingerlings of grey mullets and Sarotherodon aureus that were introduced into Lake Kinneret caused the extinction of D. lumholtzi.     

Substitution effect of sea tangle (ST) (Laminaria japonica) with tunic of sea squirt (SS) (Halocynthia roretzi) in diet on growth and carcass composition of juvenile abalone (Haliotis discus,Reeve 1846)

Substitution effect of sea tangle (ST) with tunic of sea squirt (SS) in diet on growth and carcass composition of juvenile abalone was determined. One thousand four hundred and seventy abalones were distributed into 21 containers. Six formulated diets in triplicate were prepared. A 200 g/kg ST was included into the ST0 diet. The 200, 400, 600, 800 and 1000 g/kg of ST were substituted with the same amount of tunic of SS, referred to as the ST200, ST400, ST600, ST800 and ST1000 diets, respectively. Finally, Undaria was prepared to compare effect of the formulated diets on performance of abalone. The experimental diets were fed to abalone for 16 weeks. Weight gain of abalone fed the ST400 diet was higher than that of abalone fed the ST0, ST600, ST800 and ST1000 diets and Undaria. Weight gain of abalone fed the formulated diets was higher than that of abalone fed the Undaria. The chemical composition of the carcass of abalone was affected by dietary substitution of ST with tunic of SS. In conclusion, ST could be completely substituted with tunic of SS without retardation in performance of abalone. Abalone fed the ST400 diet substituting 400 g/kg ST with tunic of SS achieved the best growth.