虾塘投饲船载自适应速度投饲系统设计与实现

为了让投饲船能根据实时船速自动调整投饲速率,从而把虾饲料比较均匀地抛撒至沿着虾塘四周的"食道"上,研制了一种根据虾塘四周"食道"而设计的实时船速自动调节投料量的投饲系统。该系统采用超带宽(UWB)定位系统来定位船体的位置,由单片机解算出投饲船的实时行驶速度,根据船速、虾塘"食道"周长和总投饲量计算出投饲船的实时投饲速率。投饲控制系统根据计算出的实时投饲速率控制投饲机构中的舵机转角,舵机的转角与投饲机构投料口的开度一一对应,从而实现均匀投饲。在个人电脑(PC)端上位机上输入投饲船初始参数,同时显示投饲船船速和投饲机构开度大小。船速获取精度试验和投饲机构投料口开度试验显示:投饲机构投料口能在1 s内打开到与船速相对应的开度,实现投饲速率的实时调整;在船速0.5～2 m/s的工作情况下,该投饲系统投饲速率误差在2.5%以内,能够实现饲料在虾塘"食道"上的均匀投放,有较好的实用价值。     

梭子蟹单筐养殖自动投饲系统设计与试验

为解决梭子蟹单筐养殖模式下的自动投饲问题,设计了一套轨道式自动投饲系统。自动投饲系统由行走系统、投饲机、供电系统和控制系统组成。在单片机系统的控制下,行车由直流电机驱动在轨道上行走,当行车上的定位传感器感应到养殖筐边沿上的定位识别板后,投饲机对一排养殖筐同时下料。当行车走到轨道末端时,行程开关可控制行车停止前进,避免行车脱轨。试验结果表明:自动投料系统实现了定量定位自动下料,称料误差在0.3 g以内,投料精度为97%,定位识别率为100%。当水位在0.5 m范围内变化时,定位误差小于3.5 cm,满足梭子蟹单筐养殖自动投喂的要求。     

详解渔业投饲机械(下)

<正>三、工厂化养殖自动投饲机1.工作原理在鱼池上方架设跑道式H型钢轨道,导轨的长度和形状可根据现场鱼池的分布做出相应的调整,在每个鱼池的正上方设置相应的定位识别点。该样机使用反射面为80毫米×150毫米的鱼池定位识别板实现系统定位,投饲装置沿轨道行走到识别点后,安装在投饲装置上的超声     

一种水陆两用自动投饵机设计与试验研究

<正>自动投饵机是提高饲料利用率,降低养殖成本的重要设施。为解决小型池塘的投饲浪费,提高工厂化养殖水平,设计研发出一种新型的水陆两用自动投饵机。根据其工作原理,对投饵机的供料装置、高压流体装置、饵料释放装置和控制系统进行了设计与分析,采用高压流体作为供料能源,管道作为输送机构,混料释放仓作为撒料装置,PLC3系统作为控制器,并按要求制作了样机进行投喂试验。结果表明,该投饵机可以实现底部投喂,投饲深度和投饲距离具有可调性,可以满足不同池塘的需求;投饲的同时还具有增氧的作用。较传统投饵机,该投饵机具有减少饲料浪费,优化鱼类摄食环境,减少局部缺氧的优点,适合现代化渔业养殖的推广和应用。     

轨道式自动投饲系统设计与试验

针对工厂化养殖中人工投饲劳动强度大、投饲误差大、不均匀等问题,研究并设计了一种轨道式自动投饲系统。该系统由上料装置、行走装置、投饲装置和控制装置4个部分组成。控制部分以可编程辑控制器(PLC)为核心、触摸屏为人机界面,采用低压气力输送的方式上料,驱动行走小车运行的方式进行饵料输送,控制螺旋下料装置和旋转抛撒盘的方式进行定量、均匀的饵料抛撒。结果显示:可以实现4个养殖池的饵料投喂,6次投喂等待时间设定,行走速度达18.75 m/min,投饲量精度在0.5%~2.2%,投饲速度1 kg/min左右,定位精度110 mm左右。该投饵系统具有投饲精度高、均匀、高效率等特点,可有效提高饲料利用率和降低劳动强度,从而减少工厂化养殖成本。     

多层水槽式工厂化循环水养殖系统智能投饲车设计

为解决多层水槽式工厂化循环水养殖模式中人工投料操作空间局促、劳动强度大、饲料利用率低等缺点,设计了一套基于K60单片机的小微型智能投饲车。该投饲车由循迹小车、投饲装置和控制系统等组成,在特定投饲跑道上行驶,根据红外对管采集的轨道信息和压力传感器采集的饲料信息判别是否投饲或补料,进而实现智能定点定量投饲。初步试验运行结果显示,该投饲车运行稳定可靠,运行速度0. 5～2. 2 m/s,投饲的定位精度误差在2 cm以内,投饲量误差在10 g以内,基本满足设计要求。     

投饲范围可控的自动投饲机研究

为解决水产养殖用投饲机投饲范围固定、投饲不均匀、饲料利用率低及污染严重等问题,提出并研制了基于气力输送和单片机控制的投饲范围可控的自动投饲机.根据其工作原理,对该自动投饲机的供料系统、抛撒系统和控制系统进行了设计,采用气力作为供料能源,喷嘴和凸台组合作为抛撒机构,选用STC90C516RD+作为控制单元.工作过程表明,与传统投饲机相比,该自动投饲机具有结构简单、饲料不易破碎、饲料利用率高、噪声污染小等特点,并可实现对投饲范围的调节和控制,达到预期投饲范围调节和均匀投饲的效果.     

一种集成自动投饲与排污的鱼类养殖系统

为提高鱼类养殖中投饲和排污的定时、定量精度及节水效果,降低劳动强度,采用新型PLC、螺旋杆送料机构、减速电机、撒料盘、液位传感器、造流器、电动阀、自动双通道排污装置等,参考人工养殖流程设计开发出一套集成自动投饲与排污的鱼类养殖系统,该系统容积1.57 m~3,适宜养殖密度低于23 kg/m~3。对系统进行了设备性能测试及鱼类养殖试验,结果显示:该系统可自动进行喂食前水流调控及自动投饲后的自动排污步骤,其中投饲机部分投饲能力0.3 kg/min,投饲量误差在±0.5 g以内,且撒料均匀度高,使用该系统养殖的2018年长江鲟子三代较传统流水养殖的鱼体平均增重提高了35.56%,饲料系数降低了26.28%,养殖初末体质量变异系数下降了31.46%;运行过程无需人工参与,集排污效果与大换水排污无明显差异,且节水90%。测试中系统运行稳定。     

基于摄食声学的投饵系统设计

针对现在船载式投饵机自动化程度低,人工抛撒成本高、劳动强度大、抛撒不均匀,该文提出了一种基于声学的投饵系统设计。该装置利用Labview声信号采集控件通过罗非鱼鱼群喂食时现场的水下声信号识别,监测和分析鱼群摄食情况,分析该鱼群进食欲望,反馈并制定投饲决策,并驱动舵机和电动推杆实现水平和垂直方向的调整,实现投饲点的控制。该设计可实现对投饲现场的声信号采集和分析,实现对养殖的罗非鱼提供投喂决策。以stm32单片机作为核心,设计的投饵控制系统,驱动执行机构完成抛撒饵料动作。这个设计有望改变目前传统人工以手执投料管的形式定量投饵的行业现状,实现养殖鱼饲料的定向按需投喂。     

高密度养殖池塘自动气力投饲机的设计试验

为解决池塘高密度养殖过程中的投饲机承载量小、投饲不均匀、投饲范围小、饲料利用率低等问题,提出一种基于气体输送原理的自动投饲机。根据其工作原理,对投饲机的供料系统、输送系统、抛料系统和控制系统进行了设计与分析,采用气力作为供料能源,管道作为输送机构,撒料盘作为抛料机构,西门子S7-200PLC作为系统控制单元。结果显示,该自动投饲机能同时满足6个池塘的投喂,并能单独控制,满足池塘的投饲需求;投饲距离达20 m,平均投饲速度400 kg/h,破碎率低于0.9%,基本满足设计要求。与传统池塘投饲机相比,该投饲机具有结构简单、操作方便,饲料不易破碎、饲料利用率高等特点,并可实现对投饲量精确调节与控制。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.     

Production of diatom–bacteria biofilm isolated from Seriola lalandi cultures for aquaculture application

Controlled incorporation of selected microalgae and bacteria in aquaculture systems can be beneficial because they can act as microbiological control. That is why the characteristics of biofilm generated naturally in Seriola lalandi culture cages were analysed, their potential benefit to the growth of larvae was studied, and their controlled use for improving the larval viability and as a vector to improve incorporation of previously studied probiotic bacteria was tested. According to biodiversity results, these biofilms are composed of a diatom–bacteria mix showing a decrease in biodiversity in laboratory culture conditions being dominated by Navicula phyllepta and bacteria of the family Rhodobacteraceae. This can be produced on mesh substrates incorporated in bioreactors with rapid growth rate and adhesiveness. Preliminary results from the addition of substrates with this specific biofilm in larvae culture systems showed that it is consumed by the larvae without negative effects, while positive effects on the viability of larvae in combination with probiotics were observed. Considering preliminary results, the addition of these specific substrates with diatom–bacteria biofilms could be a good improvement for aquaculture systems and together with the use of probiotics can contribute to maintaining a stable and controlled system improving the viability of the larval fish culture in its early stages.