The Influence of Livefeed Supplementation on Growth and Reproductive Performance of Swordtail (Xiphophorus helleri Heckel 1848) Broodstock

The influence of supplementation of drum-dried flake feed with various levels of Daphnia sp. on the growth and fecundity of broodstock Xiphophorus helleri was evaluated. Weekly supplementation showed no measurable advantage over flake feed only. A direct correlation was demonstrated between fecundity and size of female fish when fed a formulated flake feed only. Fish fed a daily Daphnia supplement had a mean final weight of 5.97 g, feed conversion ratio of 1.33 and mean fecundity of 190 embryos per female, which was significantly higher than the yield from the non-supplemented or weekly supplemented treatments. Despite these differences, the number of young harvested during the experiment did not differ (P > 0.05) between treatments and this discrepancy was ascribed to parental cannibalism of new born juveniles. This revised version was published online in August 2006 with corrections to the Cover Date.     

集约化养殖条件下暗纹东方魨生长特征的研究

报道了在集约化养殖条件下４～２０月龄暗纹东方的生长特征。其中体长、体重的相对生长率和生长指标皆随月龄增加而逐渐下降。体长与体重呈指数曲线相关，方程为，体长、体重的生长方程分别为Ｌ＝１１９．５６Ｌｎ（ｔ）－９０．４６９，Ｗ＝０．４１２７ｔ。试验表明，暗纹东方纯在集约化养殖条件下具有良好的生长潜力，可进行规模化商品鱼养殖。     

Effect of Salinity on Growth and Survival in Juvenile Opossum Pipefish,Microphis brachyurus,in Culture Conditions

Natural populations of the opossum pipefish, Microphis brachyurus, are affected in Mexico by anthropogenic alteration of their habitat and unregulated fishing as this species is traded as an aquarium fish without formal records as occurs with other syngnathids around the world. M. brachyurus is an estuarine fish adapted to salinity fluctuations. The aim of this study was to examine the effect on growth, condition, and survival of juvenile pipefish cultured for 4 wk at salinities of 0, 8, and 16 g/L. Pipefish were fed enriched Artemia nauplii maintaining a ration rate of 14% body weight per day (dry weight Artemia: wet weight fish). Pipefish cultured at 16 g/L showed lower survival (40%) than those at 0 and 8 g/L (100 and 96%, respectively), while juveniles cultured in 8 and 16 g/L were heavier (0.393 and 0.388 g, respectively), longer (9.9 cm), and grew faster (1.4) than those in 0 g/L (0.294 g, 9.1 cm, and 0.44, respectively). This study is the first to report that a salinity of 16 g/L compromises M. brachyurus culture potential and a salinity of 0 g/L caused poor growth while the optimal salinity for the species appears to be around 8 g/L.     

光对红剑鱼红色素细胞色素颗粒运动的影响及其机制

为了研究光对色素细胞色素颗粒运动的影响机制,以红剑鱼(Xiphophorus helleri)鳞片上红色素细胞为材料,体外培养后在显微镜下观察色素颗粒对不同波长光刺激的应答,并利用药理学手段研究色素颗粒对光应答的信号通路。结果表明:1)紫外光(350 nm,WU)、蓝光(450 nm,WB)、绿光(550 nm,WG)对红色素细胞色素颗粒的运动有不同影响;WB使色素颗粒聚集,WG使色素颗粒分散,而WU使红色素细胞剧烈收缩,色素颗粒聚集于细胞中心。2)双信使通路中的IP3通路可抑制色素颗粒的聚集反应;蛋白激酶C(PKC)的抑制子星孢素(ST)和H-7不影响WU引起的色素颗粒聚集反应,而IP3的抑制剂W-7可使色素颗粒聚集反应加快。3)色素颗粒运动反应与细胞内环腺苷酸(cAMP)水平有关;腺苷酸环化酶激活剂佛司可林(FSK)和cAMP-PDE阻断剂茶碱可抑制色素颗粒聚集反应,而蛋白激酶A(PKA)特异抑制子H-89可抑制色素颗粒的分散反应。以上结果提示,光对红色素细胞色素颗粒运动的影响可能是通过信号通道cAMP路径和IP3路径的共同作用     

亲虾规格、隐蔽物、光照度及密度对克氏原螯虾繁殖效果的影响

按照正交试验设计原理,不考虑交互作用,选择L9(3～4)正交表,研究了亲虾规格、隐蔽物、光照度及放养密度4个因素对克氏原螯虾亲虾成活率、抱卵率、产卵量的影响,试验历时57d。研究结果表明,不同亲虾规格对抱卵量影响显著(P0.05),且规格为35～50g亲虾的平均抱卵量为489.8粒/尾,分别较25～30g、30～35g高20.8%、11.6%;不同隐蔽物种类对亲虾的成活率影响显著(P0.05),使用"水草+石棉瓦+砖块"作为隐蔽物,亲虾平均成活率为95.69%,分别较"水草+石棉瓦+PVC管"、"三角形栖息物"高9.6%、3.5%;光照度为50～500lx,亲虾的平均抱卵量为467.17粒/尾,高于其他两个光照度水平;放养密度为20尾/m2,亲虾的平均抱卵率为64.98%,高于其他两个密度水平。因此,亲虾规格为35～50g、隐蔽物种类为‘水草+石棉瓦+砖块’、光照度为50～500lx、放养密度为20尾/m2"组合有利于提高克氏原螯虾的繁殖效果。     

Performance of Different Types of Commercial Feeds on the Growth of Juvenile Silver Pomfret, Pampus argenteus, under Tank Culture Conditions

The present study was carried out using juveniles of silver pomfret, Pampus argenteus, produced in the hatchery by stripping eggs from spawners collected from the wild during 2004 and 2005 culture period. The experiments carried out during 2004 investigated the efficiency of using salmon feed mixed with cyclopeeze, salmon feed mixed with shrimp meat, salmon feed alone, and shrimp meat alone in the diet using 1 m³ capacity round fiberglass tanks in three replicates for each treatment with flow‐through seawater. The results showed that inclusion of shrimp meat in the diet either with salmon feed or alone give significantly high (P < 0.01) weight gain of up to 1.10 ± 0.06 g/fish/d and significantly lower (P < 0.001) feed conversion ratio compared to that of feeds without shrimp meat. The experiments carried out during 2005 investigated the use of commercially available feeds with feed additives. The results showed that feeding with “Gemma” feed with 54.0% crude protein and 19.0% crude fat or salmon feed with 41.4% crude protein and 23.9% crude fat give significantly high (P < 0.01) growth rates compared to that of pompano feed with 43.0% crude protein and 6.0% crude fat. The results of these investigations although show high growth rate of the fish compared to that of previous observations; there is yet an urgent need to formulate a suitable feed for this fish species for commercial ventures.     

Effect of Temperature on Growth and Survival in Juvenile Opossum Pipefish,Microphis brachyurus: First Observations on the Species in Culture Conditions

In Mexico, natural populations of the opossum pipefish, Microphys brachyurus, are under pressure by anthropogenic alteration of their habitat and unregulated fishing as this species is traded as an aquarium fish, where its survival is low due to inadequate culture practices. The development of culturing techniques has been a successful strategy to protect many exploited species through providing an alternative source to wild exploitation. The aim of this study was to examine the effect on growth, condition, and survival of pipefish cultured for 6 wk at temperatures of 26, 28, and 30 C. Pipefish were fed enriched Artemia nauplii maintaining a ration rate of 14% body weight per day (dry weight Artemia : wet weight fish). The pipefish cultured at 26 and 28 C were longer, heavier, grew faster, and presented better condition than those at 30 C. The survival of pipefish cultured at 26 C was greater (83%) than at 30 C (30%) but not different than at 28 C (50%). This study is the first to report the acceptance of Artemia nauplii by juveniles of the species and that a temperature of 30 C is not suitable for juvenile M. brachyurus culture.     

Effect of varying dietary lipid and protein levels on growth and reproductive performance of female swordtails Xiphophorus helleri (Poeciliidae)

We conducted a study to determine the effect of dietary protein and lipid levels on the growth and reproductive performance of a freshwater ornamental species, the swordtail (Xiphophorus helleri). Two protein levels (20% and 30%) with four lipid levels (8%, 12%, 16%, 20%) within each protein levels were tested through formulation of practical diets labelled as 20P8L, 20P12L, 20P16L, 20P20L, 30P8L, 30P12L, 30P16L and 30P20L respectively. Results showed that dietary protein level significantly influenced final weight, weight gain and specific growth rate, while dietary lipid did not influence any of these growth parameters. More specifically, increasing dietary lipid levels from 8% to 12–16% in both 20% and 30% protein levels significantly improved swordtail growth performance. Dietary protein levels positively influenced gonadosomatic and hepatosomatic indexes. Both dietary protein and lipid significantly influenced female muscle protein content. Significantly highest fry production was obtained from diets 30P12L and 30P16L, respectively, while diet 20P8L resulted in the lowest fry production. This present study indicates the dietary protein and lipid requirements for female swordtails for optimized growth and reproductive performances to be at 30% and 12% respectively.     

Effect of Direct Transfer to Different Salinities on Early Juvenile Pot‐bellied Seahorse,Hippocampus abdominalis,Survival in Culture Conditions

In Tasmania, commercial seahorse culture takes place in tank systems in which approximately 75% of the water is exchanged daily from the Tamar River estuary. The aim of this study was to examine the effect on survival of early juvenile pot‐bellied seahorses, Hippocampus abdominalis, directly transferred and cultured for 9 d in salinities of 5, 10, 15, 20, 25, and 32 g/L. Direct transfer of seahorses to 5 g/L salinity resulted in 100% mortality within 7 d. After 9 d, an improvement in survival was recorded in seahorses cultured in 10 and 15 g/L compared to those cultured in 25 and 32 g/L salinities. This study is the first to report on the tolerance of H. abdominalis in captivity at salinities as low as 10 g/L in early life stages without compromising survival.     

The Effect of Initial Stocking Density on Growth and Survival of Pike-perch Fingerlings Reared under Intensive Conditions

Pond-nursed pike-perch (Sander lucioperca) fry were trained to artificial diet and reared under controlled conditions maintained in aquaria using three stocking densities (1.25, 1.66 and 2.08 g/l). Two replicates per treatment were applied. The survival during the 4-week period of the experiment ranged from 44.2 to 49.6%. The majority of the losses were caused by cannibalism; only 8–14% could be attributed to natural mortality. Both cannibalism and natural mortality occurred in the first 2–3 weeks of rearing. The differences in the rate of cannibalism were independent of the stocking density. Natural mortality decreased with increasing density, consequently the highest survival was observed under the highest stocking density. Stocking density did not significantly influence growth, feed consumption and feed conversion ratio of the pike-perch fingerlings (p < 0.05).     

剑尾鱼脑细胞系的建立及细胞色素P4501A的诱导表达

为了构建剑尾鱼脑细胞系并探讨其细胞色素P4501 a(CYP1A)基因的诱导效应,实验通过胰蛋白酶消化法对剑尾鱼脑组织进行体外培养,经连续继代培养,建立了可稳定传代的脑细胞系,命名为SFB.SFB最适培养液为含有15％胎牛血清(FBS)的DMEM/F-12和L-15等比混合培养液,培养条件为27℃,5％ CO2.生长特性研究表明,第65代细胞的群体倍增时间为43.048h,显示出旺盛的生长和分裂能力.染色体分析发现,培养细胞的染色体众数为48条,SFB核型公式为2n =2st +46t,臂指数(NF) =48,与剑尾鱼一致.诱导实验表明,SFB在10-8～ 10-5 mol/L的苯并(a)芘诱导下,CYP1A mRNA表达量显著提升,且表现出良好的剂量效应关系.脑细胞系的建立为剑尾鱼的毒理学评价研究提供了便利,也为其系统的生态毒理学应用打下基础.     

Effect of Golden Shiners on Plankton and Water Quality in Ponds Managed for Intensive Production

Water quality variables and plankton were monitored and compared between ponds that were stocked or not stocked with golden shiners in order to determine what changes occur in the plankton community and water quality of ponds managed for intensive production. Ponds with shiners had significantly lower phosphate and carbon dioxide concentrations and lower carbonate alkalinity than ponds without shiners. No significant difference in nitrite, nitrate, ammonia, temperature, secchi disk readings, or turbidity levels was found between the treatments. The standing crop of phytoplankton was nearly twice as great in ponds with fish. Ponds with fish had significantly fewer copepods but more rotifers than fishless ponds. Although the fish were offered a commercial feed with 29.5% protein and 1.5% crude fat at 3% of their biomass daily, they apparently continued to feed on crustacean zooplankton.     

Effect of Water Exchange Rate on Production, Water Quality, Effluent Characteristics and Nitrogen Budgets of Intensive Shrimp Ponds

Water exchange is routinely used in shrimp culture. However, there are few, if any, systematic investigations upon which to base exchange rates. Furthermore, environmental impacts of pond effluent threaten to hinder further development of shrimp farming in the U.S. The present study was designed to determine effects of normal (25.0%/d), reduced (2.5%/d) and no (0%/d) water exchange on water quality and production in intensive shrimp ponds stocked with Penaeus setiferus at 44 postlarvae/m². Additional no-exchange ponds were stocked with 22 and 66 postlarvae/m² to explore density effects. Water exchange rates and stocking density influenced most water quality parameters measured, including dissolved oxygen, pH, ammonia, nitrite, nitrate, Kjeldahl nitrogen, soluble orthophosphate, biochemical oxygen demand, phytoplankton and salinity. Reduced-exchange and no-exchange treatments resulted in reduced potential for environmental impact. Mass balance of nitrogen for the system indicates that 13–46% of nitrogen input via feed is lost through nitrification and atmospheric diffusion. Growth and survival were excellent in ponds with normal exchange, reduced exchange, and a combination of low density with no water exchange. A combination of higher stocking density and no water exchange resulted in mass mortalities. Mortalities could not be attributed to a toxic effect of any one water quality parameter. Production was 6,400 kg/ha/crop with moderate stocking density (44/m²) and reduced (2.5%/d) water exchange and 3,200 kg/ha/crop with lower stocking density (22/m²) and no water exchange. Results indicate that typical water exchange rates used in intensive shrimp farms may be drastically reduced resulting in a cost savings to farms and reduced potential for environmental impact from effluent.     

The Completed Life Cycle of the Octopus (Octopus vulgaris, Cuvier) under Culture Conditions: Paralarval Rearing using Artemia and Zoeae, and First Data on Juvenile Growth up to 8 Months of Age

This paper shows innovating results on Octopus vulgaris Cuvier 1797 growth under culture conditions during the whole life cycle. Experiments were conducted at the Spanish Institute of Oceanography of Vigo (Spain). Using mean water temperature of 22.5°C, salinity of 35‰ and adult Artemia (1–4 mm of total length) along with a diet complement of Maja squinado zoeae as living prey, it was possible to obtain a 31.5% paralarval survival at day 40 after hatching. At this age, paralarvae had reached a dry weight of 9.5 mg, 23 suckers per arm, and they began the settlement process. First results on juvenile growth showed that they reached 0.5–0.6 kg at the age of 6 months after hatching, and 2 months later, they attained weights ranging between 1.4 and 1.8 kg. Mean temperature of the ongrowing process was 18°C.     

Assessment of Five Shelter Types in the Production of Redclaw Crayfish Cherax quadricarinatus (Decapoda: Parastacidae) Under Earthen Pond Conditions

An experiment was designed to assess the relative performance of several shelter types on the production of redclaw crayfish Cherar quadricarinatus under earthen pond conditions. Juvenile crayfish with a mean stocking weight of 12.76 g were cultured in 24 net pens at 12.5 m² within a 0.2 ha earthen pond, and were provided with one of five shelter types or no shelter over 162 d. The various shelter types assessed were: mesh bundles, pipe stacks, car tires, elevated cement/fiber-board sheets, and cement/fiber-board sheets laid flat on the substrate. Crayfish in each pen were fed a formulated pellet diet three times each week. Treatments were assessed on the basis of crayfish growth, survival, harvest biomass and berry rate among females at harvest. There was no significant effect ( P > 0.05) of shelter type on growth; however, there was a highly significant effect ( P < 0.001) on survival with mesh bundles (75.1%), tires (51.4%), and pipe stacks (43.25%) performing significantly better than the no shelter control (15%). The consequence of equal growth and differing survival among treatments produced significant differences in harvest biomass ( P < 0.01). There were also significant differences in berry rate for the different treatments ( P = 0.002), and a significant negative correlation of berry rate on survival for those treatments where shelter was provided. This experiment showed that the shelter types provided during pond culture had a significant effect on harvested biomass, primarily through its effect on survival. The efficacy of the mesh bundle shelters may be attributable to the variability in the size of the spaces provided, and the ability of the mesh to separate many individuals relative to the overall volume of the shelter.     

Effect of Photoperiod Manipulation on Broodstock Spawning, Fertilization Success, and Egg Developmental Abnormalities in Atlantic Cod, Gadus morhua

Spawning activity in two captive Atlantic cod broodstock groups previously captured from the wild stock fishery was monitored over three spawning seasons. Both groups spawned under ambient photoperiod (PP) in the first year, after which photomanipulation was applied to compress the PP cycle of one broodstock group, while the second group was maintained on natural PP. Increased total egg volumes, number of egg batches, total egg production, and duration of the spawning season were observed in both ambient PP and advanced PP groups in the second and third spawning seasons. Compared to ambient controls, the photoadvanced group commenced spawning earlier, had a longer spawning season, produced a lower total volume of eggs over the entire spawning season, and had lower mean daily batch volumes of eggs, and the eggs were of smaller mean diameter. Fertilization success was >90% in all years, increased in both groups in the first year after photomanipulation but declined to prior levels in the following year. No consistent difference in fertilization success was observed between advanced PP and ambient PP groups. Rates of cell development abnormalities were low (<10%) in both groups over the three spawning seasons. Abnormalities of cell symmetry and clarity increased in both ambient PP and advanced PP groups over the three spawning seasons. However, no consistent differences in rate of cell abnormalities were observed between advanced PP and ambient PP groups within years. We conclude that PP advancement is an effective technique to compress the time between successive spawning periods in Atlantic cod and does not negatively affect fertilization success or rates of cell developmental abnormalities. However, it has a negative effect on both volume and size of eggs produced.     

Pond Culture of Larval and Juvenile Cobia,Rachycentron canadum,in the Southeastern United States

Abstract

The potential of growing larval and juvenile cobia, Rach-ycentron canadum, in ponds was investigated. Larval cobia, obtained from tank spawning of wild-caught adults, were stocked 48-72-h post-hatch at a rate of 700,000/ha into three fertilized 0.25-ha ponds. At one week post-stocking (WPS), fish were observed consuming formulated feed. Growth was rapid, with specific growth rates (SGR) ranging from 12.5-19.2% body weight/day. At harvest (5 WPS) fish reared in two ponds weighed 7.9 and 9.3 g and total length (TL) was 118.9 and 129.3 mm, respectively (all fish reared in remaining pond died the night prior to harvest due to aerator failure). Feed conversion ratio (FCR) was 3.8 for both ponds and survival was 5.3 and 8.5%. Low survival rates were thought to be due primarily to cannibalism. Immediately after harvest, fish were restocked into two 0.25-ha ponds at a stocking rate of 14,400/ ha. Fish were fed formulated, pelleted feeds. Growth was rapid up to ～9 WPS, after which pond water temperatures declined. Ponds were harvested at 13 and 15 WPS, respectively. Final weight of fish was 309.9 and 362.5 g. Final TL was 343.1 and 355.7 mm. FCR was 3.8 and 4.5 and survival was 27.5 and 30.5%. Major losses of fish were associated with avian predators and possibly a toxic algal bloom. Results of trials indicate that cobia larvae and juveniles can be reared in pond-based culture systems, however additional research is needed to refine this approach.     

Survival Rates of Black Sea Turbot (Psetta maxima maeotica, L. 1758) Broodstock Captured by Gill Nets from Different Depths and their Adaptation Culture Conditions

A study was performed during Spring 2002 to determine the survival rates of Black Sea Turbot (Psetta maxima maeotica) broodstock captured by gill nets from different depths (20 m, 20–45 m, and 45 m) in Sinop Bay (Black Sea, Turkey) and their adaptation to culture conditions. The weight of captured females ranged between 1.6 and 5.5 kg, while males ranged between 1.1 and 3.7 kg. Within 23 h of capture the fish were transported to Çanakkale (Marmara Sea, Turkey). During transportation, the stocking density ranged from 19 to 40 kg/m³ and no mortality was recorded. At the end of the fishing operations, the survival rates were calculated for Group 1 (20 m), Group 2 (20–45 m), and Group 3 (45 m) as 24.9, 71.4, and 92%, respectively. There were significant differences (p < 0.05) between the survival rates of the groups. Eggs and sperms were obtained by hand-stripping. The mean fertilisation rate of the eggs was 3.19%. This low fertilisation rate was due to overripened eggs. At the end of adaptation period of 1 month, the survival rates of the broodstock were found to be 14.2, 45.4, and 48.3% for Groups 1, 2, and 3, respectively. No significant difference was found between the survival rates of the broodfish during the adaptation period (p > 0.05).     

池养香鱼亲鱼的批量培育和采卵技术研究

采用流水刺激、缩短光照、降温、改善饵料营养等多种措施，促使池养香鱼亲鱼性成熟并自然排卵，采取降温的方法诱导产卵，较好地解决了池养香鱼的批量培育和采卵等关键技术，取得亲鱼自然排卵率平均88.6％，受精卵发眼率平均80.1%，孵化率^*91.4%的结果。     

集约化养殖条件下暗纹东方鲀行为习性的初步观察

通过一个完整的商品鱼养殖周期,观察并定性描述了集约化养殖条件下暗纹东方鲀的行为习性,主要包括栖息习性、对水温及溶氧的反应、游泳行为、摄食行为、鼓气行为、攻击及相残行为等,同时结合养殖生产对行为的应用进行了探讨。