Feeding requirements of sea bream (Sparus aurata) larvae under intensive rearing conditions: Development of a fuzzy logic controller for feeding

Applied methods for larval rearing suffer from the difficulty of accurately predicting larvae quantitative feeding requirements for optimum growth. Even when known, requirements change according to the behavior of each population reared. Computer based feeding systems require tools for adapting the delivered amounts of food to the needs of the reared population. In this work the daily feeding requirements of sea bream (Sparus aurata) larvae were estimated, and based on these estimations a fuzzy logic controller (FLC) for feeding was designed and developed. Sea bream larvae were reared, in triplicate, under intensive conditions in a pilot scale rearing system for 20 days with the pseudo-green water method. Larvae reached 6.7±0.6 mm (mean value and S.D.) at the end of the experimental period while the mean survival of the populations was 48.0±12.6%. Consumption was 0.017±0.009 mg of carbon per individual at first feeding and increased to 0.198±0.032 mg at day 20 post-hatching. The findings were used for the development of a FLC for feeding that adapts the amount of food delivered to the larvae according to changes in the reared population. The FLC utilizes five linguistic variables describing the state of the population and a rule base composed of 316 rules. The developed FLC allows the use of computer based feeding systems during rearing of early larval stages.     

循环水养殖半滑舌鳎成鱼摄食活动对主要水质因子的影响

在封闭循环水养殖条件下,半滑舌鳎(Cynoglossus semilaevis Günther)的平均养殖密度(15.07±0.22)kg/m3,观测半滑舌鳎的呼吸频率,检测养殖水体中溶氧、氨氮、亚硝酸氮等24 h内摄食和代谢的变化规律。结果表明:(1)半滑舌鳎摄食前、后的呼吸频率平均值分别为27.3次/min和34.7次/min,摄食后的呼吸频率显著高于摄食前;(2)投喂前、后2.5 h内,水中溶氧一直处于下降趋势,在摄食2.5 h后,水中溶氧处于稳定的上升趋势;(3)投喂后,氨氮、亚硝酸氮浓度显著增高,2.5 h后达到峰值,随后缓慢降低,在下次投喂前0.5 h达到最低值。说明半滑舌鳎摄食活动对循环水养殖水质的影响呈现规律性,也说明循环水养殖模式可以满足半滑舌鳎对水质的基本要求。     

An automated recirculation aquaculture system based on fuzzy logic control for aquaculture production of tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>)

The development of an automated recirculation aquaculture system (ARAS) is presented here. The production system facility was built in a 672-m² polyethylene greenhouse using four 20-m³ tanks, each of which was stocked with 1,000 tilapia (O. niloticus). The growth of the fish was evaluated from a starting weight of 2 g to a final average weight of 418 g, during a production cycle from July 2008 to January 2009. Our objective was to develop new technological approaches, based on fuzzy logic control, to integrate into novel automated equipment for recirculation aquaculture systems used for fish production under intensive conditions. This technique allows farmers to incorporate their knowledge and experience into the control system. The results demonstrated a substantial water savings of 97.42%. There was a total fish biomass production of 1,655.3 kg and an average feed conversion rate of 1.55. The environmental variables were kept within acceptable ranges for tilapia production. We conclude that it is possible to increase the productivity and profitability of aquaculture systems, by applying new approaches based on modern control techniques, such as fuzzy logic control, that promote resource optimization.     

工厂化水产养殖中的水体参数监测和控制

在工厂化水产养殖中,有许多水体参数需要检测和控制。本文对使用物理手段准确控制的参数,即温度,溶解氧,pH值进行研究,说明控制的意义,提出控制方法,并建立组态工程,方便对重要参数进行在线监测和控制。     

Selection for improved stress tolerance in rainbow trout (Oncorhynchus mykiss) leads to reduced feed waste

The magnitude of the cortisol response to a standardised stressor is a heritable trait in salmonid fishes, and selection for stress responsiveness induces differences in both behaviour and neuroendocrine function. For instance, in laboratory studies, fish with a high cortisol response show a greater propensity for stress induced anorexia. Some authors have, however, commented that controlled studies encompassing relatively small groups of fish hold little or no relevance to practical aquaculture. This notion may be flawed, since understanding the mechanisms behind the behaviour of individuals is a proviso to predict behaviour in groups even with the caveat that some behaviors may be modified by group size. As an example, optimal feeding regimes should be easier to predict in a population consisting of individuals whose appetite is relatively less affected by external stressors. In a fluctuating and potentially stressful environment, such a population should also generate less feed waste, if kept on fixed rations. In the present experiment, we tested this hypothesis by monitoring feed waste and feed conversion efficiency in lines of rainbow trout selected for a low (LR) or high (HR) cortisol response to stress. The study was carried out after fish had been transported between rearing sites in the United Kingdom and Norway. There was significantly more feed waste from rearing units containing HR fish, and these fish also showed lower feed efficiency (growth per unit feed consumed). The difference in feed waste became more apparent with increasing time after transport, as rations increased. Simultaneously, size was more variable and growth was slower in HR rearing units. These results suggest that there are several potential benefits of selection for low stress responsiveness in aquaculture.     

The economic impact of feeding restrictions on US catfish, Ictalurus punctatus (Rafinesque), aqafuaculture operations

Increasing stocking densities in catfish, Ictalurus punctatus (Rafinesque), aquaculture are making maintenance of water quality a crucial element of production strategy. A bioeconomic simulation model for catfish has been adapted to assess alternative feeding restriction management strategies for US catfish aquaculture operations. The current model includes five decision variables: feeding rate, diet quality, stocking weight, stocking date, and length of growing season. The growth model follows a bioenergetics approach, where the balance between energy intake and energy expenditure determines fish growth. The purpose of this analysis was to simulate changes in production practices resulting from water quality restrictions. Model simulations indicate that restricting maximum daily feeding allowance to maintain higher water quality will actually increase feed requirements to reach a harvestable fish size. In addition, as producers increasingly attempt to spread harvests throughout the year, both for their own cash flow needs and the consistent supply requirements of processors, restricting daily feed allowance will make summer harvests particularly difficult.     

First feeding of common wolffish on formulated dry feed diets in a low water-level raceway system

Wolffish (Anarhichos lupus) larvae were first fed in a low water-level raceway system, with two new types of formulated dry feed diets. Water level in the rearing tank was 1.5 cm. The fish showed a high preference for feeding from the surface. During the first week the fish experienced a drop in dry weights. The highest SGR of 5.8% was obtained between day 35–60. The best feeding regime gave a survival rate of 82 (2.5)%. Results indicate failure to initiate feeding as a main cause of mortality in the fed groups. Death by starvation occurred after 30–40 days. It is speculated whether the large difference in growth rates between the two feeding regimens is due to differences in carbohydrate levels between the two feed types. The rearing tank technology proved, with minor adjustments, to be self-cleaning and well suited for first feeding of wolffish.     

Are restricted periods of over-stocking of recirculating aquaculture systems advisable? A simulation study

Fish stocking is an important element of aquaculture management. A constant stocking rate is a convenient strategy in intensive aquaculture, being also the best under steady physical and economic conditions. If, however, these conditions vary with time, the best stocking rate may also vary. This problem has been addressed in a previous paper, where water temperature, fish price and/or market demand were allowed to vary sinusoidally over the annual cycle, while a constant upper limit on the water-treatment capacity constrained the process. Considering only situations where feeding is always to satiation, sinusoidal stocking rates were shown to perform often significantly better than the best constant stocking-rate strategy.In this paper a further step is taken in that over-stocking (more than hitherto) for certain periods of time is allowed. This leads to restricted feeding at a later time (to avoid overload of the water-treatment system) and to some loss of feeding efficiency. Often, however, the loss in feeding efficiency is more than compensated for by better utilization of the rearing space.Optimal constant and sinusoidal over-stocking strategies were applied to eight sample combinations of sinusoidal temperature and market conditions. Restricted over-stocking often resulted in a considerable improvement of economic performance over the previous results. The potential for increase of yield and profit by over-stocking depends on the amount of under-utilization of the rearing space by the previous solution, namely when only feeding to satiation is allowed. On average (for the system under consideration) out of 10% of under-utilized space when feeding to satiation, 4.4% (almost half) can be recovered by properly applied over-stocking. Expressed in terms of feed processing capability, this 4.4% recovery is equivalent to about 16 kg[feed]/(m³[tank]y), and to an additional production of about 6.6 kg[fish]/(m³[tank]y). The gain in profit is of the order of 25 $/(m³[tank]y) per 10% of previously unutilized capacity.     

Are restricted periods of over-stocking of recirculating aquaculture systems advisable? A simulation study

Fish stocking is an important element of aquaculture management. A constant stocking rate is a convenient strategy in intensive aquaculture, being also the best under steady physical and economic conditions. If, however, these conditions vary with time, the best stocking rate may also vary. This problem has been addressed in a previous paper, where water temperature, fish price and/or market demand were allowed to vary sinusoidally over the annual cycle, while a constant upper limit on the water-treatment capacity constrained the process. Considering only situations where feeding is always to satiation, sinusoidal stocking rates were shown to perform often significantly better than the best constant stocking-rate strategy.In this paper a further step is taken in that over-stocking (more than hitherto) for certain periods of time is allowed. This leads to restricted feeding at a later time (to avoid overload of the water-treatment system) and to some loss of feeding efficiency. Often, however, the loss in feeding efficiency is more than compensated for by better utilization of the rearing space.Optimal constant and sinusoidal over-stocking strategies were applied to eight sample combinations of sinusoidal temperature and market conditions. Restricted over-stocking often resulted in a considerable improvement of economic performance over the previous results. The potential for increase of yield and profit by over-stocking depends on the amount of under-utilization of the rearing space by the previous solution, namely when only feeding to satiation is allowed. On average (for the system under consideration) out of 10% of under-utilized space when feeding to satiation, 4.4% (almost half) can be recovered by properly applied over-stocking. Expressed in terms of feed processing capability, this 4.4% recovery is equivalent to about 16 kg[feed]/(m³[tank]y), and to an additional production of about 6.6 kg[fish]/(m³[tank]y). The gain in profit is of the order of 25 $/(m³[tank]y) per 10% of previously unutilized capacity.     

许氏平鲉的生物学特征及其人工养殖

本文综述了许氏平鲉的生态特征,摄食与生长、繁殖习性等生物学特征。介绍了亲鱼选择、人工培育及病害防治技术。     

Acoustical monitoring of fish density,behavior, and growth rate in a tank

A challenge for the aquaculture community has long been the development of harmless techniques for monitoring fish in a tank. Acoustic telemetry has been used to monitor fish swimming behavior, and passive acoustics have been used to monitor fish feeding, but new techniques are needed to monitor non-invasively their numbers and growth rates. Recently, it has been demonstrated that the acoustical total scattering cross section of fish swimming in a tank can be measured from multiple reverberation time series. These measurements have been used successfully to estimate the number of fish in a tank in laboratory conditions, and to characterize their acoustical signatures. Here, we introduce a novel method for acoustically monitoring fish numerical density and behavior, and measuring their growth rates over long periods of time. These measurements can be performed remotely, without human interaction with the fish, and are harmless. To demonstrate the efficiency of these techniques, the number of sea bass, as well as the behaviors of sardines, rockfish and sea bass, in different tanks were monitored. Also, the growth rates of a group of starved sardines and a group of fed sardines were measured acoustically, over 1 month. For comparison, their average weight was measured once per week.     

Estimation of flow in a rearing tank of marine fish larvae by simplified numerical computation—a case of two-dimensional flow

Marine fish larvae are fragile against physical stress. However, few studies have been conducted to evaluate the flow field in a rearing tank, which is assumed to provide a high degree of physical stress to marine fish larvae. The flow field in a rearing tank (volume of 1 m³) is generated by aerators, which are commonly used to provide oxygen.

This paper is a report on the estimation of stationary flow in the rearing tank of marine fish larvae. The larvae are seven band grouper larvae of Epinephelus septemfasciatus, which have a very low survival rate immediately after the hatching of eggs. The experiments of rearing of seven band grouper larvae were carried out using rearing tanks with four aeration rates (1000, 200, 50 ml/min, and no aeration). The effects of aeration on the survival and floating death of seven band grouper larvae were examined. The experiments confirmed that the mass mortality of seven band grouper larvae depends on the flow rate in the rearing tank. Aeration at 200 ml/min resulted in the highest survival and growth rates of grouper larvae.

Larvae-rearing experiments provided evidence that the flow rates of the rearing tanks are very important design aspects of rearing tanks. The estimation of flow in a rearing tank for an aerating rate of 200 ml/min was carried out by numerical calculation. The computation was simplified by a two-dimensional flow based on experimental results. The calculated flow in the rearing tank was compared with the experimental one. The calculation of the stationary flow in the rearing tank showed good qualitative and quantitative agreement with the experimental results. The numerical estimation of the flow in a rearing tank of marine fish larvae was confirmed to be effective and satisfactory for the design of a tank that would provide optimum performance.     

Process modelling of an intensive aquaculture system

The application of process modelling concepts to an intensive recirculating aquaculture system is described. Advanced Continuous Simulation Language (ACSL) for describing the unsteady behaviour of complex continuous flow system is applied to a simplified recycle fish rearing system comprising a rearing tank and a treatment unit. Use of the technique was validated by comparison with analytical solutions of the unsteady state mass balance equations for the transfer and removal of ammonia. The language is successfully implemented to study the dynamic behaviour of ammonia concentration and in response to changes imposed upon the system. The effects of choice of design and operating parameters upon the response of the system are illustrated. Parameters studied include vessel size, lag, flowrate, recycle ratio and mixing regime.     

Influence of stocking density on growth of juvenile red porgy Pagrus pagrus L. under different feeding conditions

The influence of stocking density and feeding regime on the growth of red porgy was studied during winter and spring 1997. Fish were held in 500-L tanks at densities of either 50 or 100 fish per tank, and were fed by means of self-feeders under 6 h restricted (day or night) or free-access feeding regimes. Fish were tagged individually, and weight gain was recorded by individual weighing every second week over an 8-week period during each season. In winter, growth was influenced by feeding time. Fish tended to grow best when fed without restriction and worst when fed at night, although differences were not significant when tank means were compared. Stocking density was influential in the spring trial. Fish stocked at low density and feeding freely grew better than high-density fish that fed either freely or at night. The division of fish into three size classes revealed that, within each treatment, no differences occurred among classes, but growth of fish belonging to the same class was influenced by rearing conditions. No significant differences were found among feeding regimes in terms of the coefficients of weight variation ratio (CV_f:CV_i) and feed efficiency.     

Evaluating the Rearing condition of Rainbow Trout (Oncorhynchus Mykiss) Using Fuzzy Inference System

Rainbow trout (Oncorhynchus mykiss) is one of the most popular aquacultured species in the world. Sustainable production of this fish at commercial scale is very important but requires maintaining good water quality throughout the total rearing period. The present study aimed to develop a rainbow trout production index in order to raise awareness about the conditions of the rearing environment, enhance production, and reduce losses. For this purpose, an intensive rainbow trout production system was selected as the study system. In this system, there were seven stations including (a) 3000 5-g fish, (b) 3000 25-g fish, (c) 3000 50-g fish, (d) 3000 100-g fish, (e) 3000 220-g fish, (f) 2000 350-g fish, and (g) 2000 830-g fish. The fuzzy inference system was used to develop the target rearing index. Water quality parameters involved in the variation in the rainbow trout rearing conditions were classified into three groups including un-ionized ammonia, nitrite, and nitrate, Alkalinity and phosphate, along with dissolved oxygen and linear velocity. For each group and condition of rearing, a separate fuzzy inference system was defined and the output of each fuzzy system was named I₁, I₂, I₃. Finally, I₁, I₂, and I₃ were considered as the inputs to a fuzzy system in order to evaluate their effects on the index of general rearing conditions (I). The results indicated that un-ionized ammonia, nitrite, nitrate, and phosphate had negative effects while dissolved oxygen, linear velocity, and alkalinity positively affected water quality and rearing index. Most of the decline in the rainbow trout rearing index was related to the effect of un-ionized ammonia, nitrite, and nitrate due to food decomposition. Therefore, intelligence feeding based on fish appetite through reducing food conversion rate and water pollution can improve rainbow trout production in this system. The index of rainbow trout production conditions reflects the type, amount, and effect of water quality pollutants on rearing conditions. Producers can use this information to reduce the negative environmental effects and improve the product quality.     

Assessing appetite of the swimming fish based on spontaneous collective behaviors in a recirculating aquaculture system

In order to realize the real-time appetite-based feeding in aquaculture, a novel and practical method, based on the quantification of the spontaneous collective behaviors, was proposed in this study to assess the real-time appetite of the swimming fish in a recirculating aquaculture system. First, foreground feature points of fish school were extracted using an improved complex network. Then, covariance, a modified social force model and a kinetic energy model were used to analyze the collective behaviors of the school from perspectives of dispersion degree, interaction force and the changing magnitude of the water flow field, respectively. Finally, the quantified behavioral characteristics were integrated and used to assess the appetite of fish school. The presented method shows its good performance in the expression of the collective behaviors representing five typical appetites (0.01, 0.52, 1.28, 2.26 and 2.92), and the assessing accuracy of the appetite of the school is also maintained at a low non-match rate ((2.19 ± 0.81)% best) in the context of ten different sampling durations.     

Aquaculture Techniques for Crappie,Pomoxis spp., Culture

Extensive crappie, Pomoxis spp., culture has been practiced for decades, however, knowledge of crappie aquaculture methods is limited. The following review synthesizes existing research on crappie aquaculture and identifies knowledge gaps where further research is needed. Topics such as life history, tank culture, feeding, reproduction and spawning, larval rearing, transport and harvest, triploidy, hybridization, and out‐of‐season spawning were reviewed. The outcome is a better understanding of hindrances preventing crappie aquaculture development in the past, particularly tank culture and induced spawning techniques, and specific research objectives with potential to enhance recreational and commercial production.     

Evaluating fish feeding intensity in aquaculture with convolutional neural networks

This paper presents a novel method to evaluate fish feeding intensity for aquaculture fish farming. Determining the level of fish appetite helps optimize fish production and design more efficient aquaculture smart feeding systems. Given an aquaculture surveillance video, our goal is to improve fish feeding intensity evaluation by proposing a two-stage approach: an optical flow neural network is first applied to generate optical flow frames, which are then inputted to a 3D convolution neural network (3D CNN) for fish feeding intensity evaluation. Using an aerial drone, we capture RGB water surface images with significant optical flows from an aquaculture site during the fish feeding activity. The captured images are inputs to our deep optical flow neural network, consisting of the leading neural network layers for video interpolation and the last layer for optical flow regression. Our optical flow detection model calculates the displacement vector of each pixel across two consecutive frames. To construct the training dataset of our CNNs and verify the effectiveness of our proposed approach, we manually annotated the level of fish feeding intensity for each training image frame. In this paper, the fish feeding intensity is categorized into four, i.e., ‘none,’ ‘weak,’ ‘medium’ and ‘strong.’ We compared our method with other state-of-the-art fish feeding intensity evaluations. Our proposed method reached up to 95 % accuracy, which outperforms the existing systems that use CNNs to evaluate the fish feeding intensity.     

The effects of swimming exercise and dissolved oxygen on growth performance,fin condition and precocious maturation of early‐rearing Atlantic salmon Salmo salar

Swimming exercise, typically measured in body‐lengths per second (BL/s), and dissolved oxygen (DO), are important environmental variables in fish culture. While there is an obvious physiological association between these two parameters, their interaction has not been adequately studied in Atlantic salmon Salmo salar. Because exercise and DO are variables that can be easily manipulated in modern aquaculture systems, we sought to assess the impact of these parameters, alone and in combination, on the performance, health and welfare of juvenile Atlantic salmon. In our study, Atlantic salmon fry were stocked into 12 circular 0.5 m³ tanks in a flow‐through system and exposed to either high (1.5–2 BL/s) or low (<0.5 BL/s) swimming speeding and high (100% saturation) or low (70% saturation) DO while being raised from 10 g to approximately 350 g in weight. Throughout the study period, we assessed the impacts of exercise and DO concentration on growth, feed conversion, survival and fin condition. By study's end, both increased swimming speed and higher DO were independently associated with a statistically significant increase in growth performance (p < .05); however, no significant differences were noted in survival and feed conversion. Caudal fin damage was associated with low DO, while right pectoral fin damage was associated with higher swimming speed. Finally, precocious male sexual maturation was associated with low swimming speed. These results suggest that providing exercise and dissolved oxygen at saturation during Atlantic salmon early rearing can result in improved growth performance and a lower incidence of precocious parr.     

Early Growth and Survival of Larval Alligator Gar,Atractosteus spatula,Reared on Artificial Floating Feed with or without a Live Artemia spp. Supplement

Alligator gar, Atractosteus spatula, are a new aquaculture species with many aspects about rearing unknown. Alligator gar are cannibalistic during their larval stage and methods to minimize cannibalism should be developed to increase overall survival. Growth and survival were determined for larvae fed pelleted floating food only or fed pelleted floating food supplemented with live Artemia spp. nauplii for the first 7 d of exogenous feeding (5 d after hatching [d.a.h.] to 12 d.a.h.). Total length, weight, condition, and specific growth rate (SGR) was determined at 12 and 20 d.a.h. Fish supplemented with Artemia were larger by 12 d.a.h. and continued to be at 20 d.a.h. than fish fed only floating food. SGR was higher at both 12 and 20 d.a.h. for fish that received the Artemia supplement. Survival was higher for fish supplemented with Artemia (71%) than for the floating food only treatment (43%). Cannibalism was the primary cause of mortalities and was higher in fish fed floating food only (44%) compared to Artemia supplemented fish (19%). Artemia may elicit a stronger feeding response and improve acceptance of pelleted floating foods. Results suggest an improved feeding regime compared to previous feeding regimes used in rearing larval alligator gar.