Behavioural indicators of welfare in farmed fish

Behaviour represents a reaction to the environment as fish perceive it and is therefore a key element of fish welfare. This review summarises the main findings on how behavioural changes have been used to assess welfare in farmed fish, using both functional and feeling-based approaches. Changes in foraging behaviour, ventilatory activity, aggression, individual and group swimming behaviour, stereotypic and abnormal behaviour have been linked with acute and chronic stressors in aquaculture and can therefore be regarded as likely indicators of poor welfare. On the contrary, measurements of exploratory behaviour, feed anticipatory activity and reward-related operant behaviour are beginning to be considered as indicators of positive emotions and welfare in fish. Despite the lack of scientific agreement about the existence of sentience in fish, the possibility that they are capable of both positive and negative emotions may contribute to the development of new strategies (e.g. environmental enrichment) to promote good welfare. Numerous studies that use behavioural indicators of welfare show that behavioural changes can be interpreted as either good or poor welfare depending on the fish species. It is therefore essential to understand the species-specific biology before drawing any conclusions in relation to welfare. In addition, different individuals within the same species may exhibit divergent coping strategies towards stressors, and what is tolerated by some individuals may be detrimental to others. Therefore, the assessment of welfare in a few individuals may not represent the average welfare of a group and vice versa. This underlines the need to develop on-farm, operational behavioural welfare indicators that can be easily used to assess not only the individual welfare but also the welfare of the whole group (e.g. spatial distribution). With the ongoing development of video technology and image processing, the on-farm surveillance of behaviour may in the near future represent a low-cost, noninvasive tool to assess the welfare of farmed fish.     

Recommendations for keeping birds of prey and owls according to animal welfare regulations

In the Federal Republic of Germany the ownership of birds of prey and owls is subject to legal provisions for the conservation of nature and wildlife, as well as to the game law. Minimal requirements for housing and care of such birds result from regulations for animal welfare. According to these--arranged as to the pertinent paragraphs--recommendations are supplied for dealing with all aspects of animal welfare in the management and care of birds of prey and owls.     

动物福利在羊驼饲养管理中的应用

羊驼饲养福利政策主要包括:根据不同生理阶段合理调整饲养方案、供给充足饮水、补充维生素和矿物质等,满足其健康生长的营养需要。管理福利政策包括卫生免疫、运动驱虫、剪毛修蹄等,尽量消除各种因素对羊驼生产性能的影响,从而为其提供一个适宜的生长环境。     

Several surgical operations in animal husbandry for healthy birds required or implemented by animal welfare regulations

Trimming of the comb, devocalisation, trimming of claws, pinioning and caponisation of birds are procedures, which are often requested or carried out by keepers of animals. Surgery of this kind, however, has far-reaching consequences for the affected animal. A well considered range of indications is a basic requirement for the performing of the mentioned surgical procedures by a veterinarian.     

Potential benefit of clove oil sedation on animal welfare during salmon smolt, Salmo salar L. transport and transfer to sea

The purpose of this study was to determine the effect of clove oil (4.0 mg L⁻¹) sedation, compared with non-sedation, on the primary (plasma cortisol), secondary (osmoregulation) and tertiary (mortality) stress responses in Atlantic salmon smolts during transport and transfer to sea. Clove oil sedation during on- and off-loading sufficiently reduced the primary stress response to lower mortality (2.1%) during transfer to sea compared with unsedated fish, which experienced a mortality rate above 12.2%. The unsedated fish experienced an acute mortality that stabilized only 6 days after the transport. None of the secondary stress responses measured in this experiment could contribute towards explaining this phenomenon, with the possible exception of plasma magnesium (Mg²⁺). Plasma Mg²⁺ differed between the groups; while plasma Mg²⁺ in the clove oil sedated group returned to pre-stress levels 72 h after transport, the unsedated group showed no such recovery even 1 week after transport, which may indicate a disturbance in the hydromineral balance, and provides a plausible explanation for the delayed mortality in this group. Eugenol-based anaesthetics appear to be promising as a stress-reducing sedative for Atlantic salmon smolts, and, if used properly, this chemical could improve animal welfare and survivability during and after common aquaculture-related incidents.     

中草药及其多糖在畜禽养殖中应用的研究进展

随着社会的发展,中医技术逐渐被人们认可,而中草药的应用也在逐步被人们所接受。文章综述了中草药及其多糖在预防以及治疗畜禽多种传染性疾病上的应用,并对其提高畜禽机体免疫力做了简单阐述,通过文献报道,中草药对这些传染性疾病起到了相应预防和治疗作用。     

Biodiversity in aquatic systems in relation to aquaculture

This paper first considers the perception and dimensions of biodiversity. We suggest that biodiversity can be viewed as a biospatial, hierarchically distributed structure of variability among living organisms with five levels of complexity (and including agricultural systems). Loss of biodiversity, value of biodiversity and knowledge of aquatic biodiversity are reviewed briefly. Methods for measuring biodiversity, especially at the genetic level, are discussed and considerable emphasis is laid on effective population size as a controlling factor in biodiversity. Finally, a range of impacts of aquaculture upon biodiversity are considered, including competitive and introgressive effects from farmed stocks. The development and use of reversibly sterile strains is seen as highly beneficial to both aquaculture and the maintenance of biodiversity.     

Using ecological indicators in the context of an ecosystem approach to fisheries for data-limited fisheries

The tenets of ecosystem approach to fisheries (EAF) now occupy centre stage in our efforts to maintain the sustainability of fisheries and rebuild marine ecosystems. The paper discusses how an EAF can be adopted for data limited fisheries and uses the northern South China Sea fishery as an example to demonstrate the selection and use of indicators for determining the states of the fishery and its relevant ecosystem to provide advice on management. Implementing EAF management requires indicators and models that address the impact of fishing across entire ecological communities and determine management actions to be taken to achieve the preset objectives according to decision rules. Data limited fisheries necessarily have limited resources for data collection and scientific studies and therefore could not support complex models. To overcome the data limitation and absence of modelling support, simple indicators have to be used to assess the current state and monitor changes of the fishery and its ecosystem. Such indicators should: (1) be observable and understandable by all stakeholders, (2) be based on easily obtainable and reliable data, (3) adequately reflect the condition of the resource, and (4) have associated reference values and responsive management measures. The paper also reviews the recent development and use of indicators and harvest strategies in both conventional and EAF management to better understand the differences and to shed light on the challenges of EAF, in particular for data limited fisheries.     

抢抓机遇 发挥优势 大力推进西部地区畜牧业产业化进程

畜牧业产业化是指遵循市场经济规律,按照产加销、牧工商、贸工牧、牧教科一体化的要求,走市场牵龙头、龙头带基地、基地连农户的路子,实现畜牧业布局区域化、生产专业化、经营规模化、服务社会化、管理企业化的目标.     

Assessment of the accuracy of physiological blood indicators for the evaluation of stress,health status and welfare in Siberian sturgeon (<Emphasis Type="Italic">Acipenser baerii</Emphasis>) subject to chronic heat stress and dietary supplementation

There is growing interest in the evaluation of stress, health and welfare of farm-raised fish. However, there is no scientific consensus about the methodology that is used to assess them. Sturgeon aquaculture is a recent industry with increasing interest in the production of caviar, which is characterized by high turnover and costs. To improve aquaculture efficiency, this study was conducted on routine blood samples, taken from Siberian sturgeon (Acipenser baerii), to test the robustness of using only physiological indicators to assess heat stress, health, and welfare. Sampling was performed after 1 month of prebiotic dietary supplementation followed by 4 weeks of sublethal heat stress. Data interpretation was achieved with a multivariate statistical tool. The expression of heat shock proteins (HSP) was assessed for the first time in sturgeon erythrocytes. Hsp70 and hsp90 expression was triggered by both stress and dietary supplementation. Indicators of non-specific immunity were modified mainly by stress. Complement activity increases with stress while lysozyme activity decreases, but to a lesser extent in supplemented fish. The antioxidant capacity increases with stress while oxidant metabolites decrease and overall oxidative stress was lower for fish that received dietary supplementation. The positive impact of dietary supplementation on health status was observable after a stress challenge. A principal component analysis was used to combine all the measured parameters and to observe patterns in physiological fish status. The four experimental groups of fish were clearly discriminated with this statistical tool. Physiological indicators from blood samples may enable heat stress, health, and welfare to be assessed in Siberian sturgeon.     

Introduction to the design of coastal aquaculture systems in Taiwan

The traditional culture of shellfish in the coastal waters of Taiwan has a long history. The culture area was limited to the sandy beaches of the south and southwest coast. In the past decade, due to the shortage of land resources and water pollution, coastal water aquaculture has been extended to intertidal rocky areas and the sublittoral zone. Concrete ponds have been constructed on the intertidal zone of the rocky coast specifically for culturing such species as small abalone, Haliotis diversicolor supertexta, grass shrimp, Penaeus monodon, grouper Epinephelus sp. etc. Fish culture in floating cages and oyster culture on floating long-lines and rafts are also practiced. This paper presents details of construction designs, with emphasis on utilizing water circulation, construction costs and wave resistance. Some examples are selected to illustrate the layouts used and the problems faced.     

鹅填肥饲料中添加动植物性油脂对肥肝性能的影响

鹅肥肝生产饲料中添加植物油脂的肥肝重平均大于动物油脂45g,但差异不显著(P>0.05),二者增重速度、屠宰性能差异不显著(P>0.05)。植物油脂添加组肠、肌腺胃重大于动物油脂组8.39%,这可能与动物油脂容易消化吸收有关。血液生化指标与酶类含量差异不显著。     

Site of acid-base relevant ion transfer in the gills of rainbow trout (Oncorhynchus mykiss) exposed to environmental hypercapnia

In order to delineate the contribution of primary vs. secondary circulatory circuits in the gill for acid-base and ionic regulation, the flow and composition of the fluids in the central venous sinus (CVS) and the systemic circuit of rainbow trout were studied by application of a previously developed microcannulation technique during normocapnic and hypercapnic conditions. The average haematocrit (Hct) of blood from dorsal aorta (DA) and sinus venosus (SV) ranged from 20.1 to 26.7%, whereas average Hct in the fluid from the branchial vein (BV), representing drainage from the central venous sinus (CVS), was in the range of 4.2 to 7.0%. Under normocapnic conditions, the largest fraction of cardiac output, 92.9%, was directed through the systemic vascular circuit, whereas the CVS circuit was perfused with 7.1 % of cardiac output. Hypercapnia did not significantly affect the blood flow distribution between the two circuits. The pattern of acid-base regulation in dorsal aortic blood reflected the characteristic response of fish exposed to environmental hypercapnia. Upon initiation of environmental hypercapnia (2% CO₂), plasma P_{CO 2} was elevated in all three flow compartments (CVS, DA, SV), inducing an extracellular respiratory acidosis of about 0.4 pH units. pH and [HCO₃ ^-] values in the DA were consistently lower, than those for both CVS and SV sites throughout the hypercapnic period. During the 8h of exposure plasma bicarbonate concentration was elevated by about 12 mM, complemented by a fall in extracellular [Cl^-] of about 10 mM in all three compartments. The amount of HCO₃ ^- gained at the CVS site during 8h of hypercapnia (3.3 mmol · kg^-1) exceeds the amount accumulated in the extracellular space (2.1 mmol·kg^-1), suggesting the CVS as the main site of ionic acid-base regulation in trout.     

Bubble size distribution in a bubble column applied to aquaculture systems

Bubble size distribution affects the gas-liquid mass transfer rates during aeration and foam fractionation processes employed in recirculating aquacultural systems. The effects of air flow rate, protein concentration and air stone pore size on bubble characterization were investigated. Bubble size was measured photographically in conjunction with image-processing techniques. The study indicated that bubble size increased with air flow rate and air stone pore size, but decreased with protein concentration. Within the tested range of these variables, the geometric diameters of the majority of the bubbles (90%) were within the range of 0·5–3·0 mm, and the bubble sizes followed a normal distribution.     

A dead-end filtration method to remove particle-associated pathogens in aquaculture systems

To reduce the incidence of bacterial diseases in recirculating aquaculture systems, 27 marine bacterial species were introduced into Instant Ocean maintained at 25°C. Those species were enumerated before and after filtration to evaluate the efficiency of the filtration procedure. The effects of sari filter and nylon filter on the survival of sea bass challenged with Vibrio alginolyticus were also determined. The results of laboratory studies indicated that the ability to remove pathogens was typically 1–3 log orders. Above 90% Vibrio sp., i.e., which were attached to particles, were removed by either 20-μm nylon net or four layers of sari. A 9.53% mortality of sea bass was reported in pilot filtration test using sari material as an end filter, while this percentage increased to 33.35% in control groups. It is concluded that a simple filtration procedure that involves the use of four-layer sari material can reduce the numbers of pathogens attached to particles in aquaculture system. The results of this study provide the basis for pathogen reductions in full-scale facilities.     

A model to predict water temperature in plastic-covered outdoor mass algal culture systems

The design, construction and operation of a 100 m² rectangular plastic-covered culture system for green algae (chlorella, scenedesmus) is described. A simple simulation model which predicts water temperature with an accuracy acceptable for estimating algal growth rate has been developed. Although simulated and measured observations showed significant statistical agreement, the model tends to underestimate daily maximum temperature and overestimate daily minimum temperature. The model can be readily adapated for usage in other parts of the world.     

Pathological Studies on an Epidemic of Caligus curtus (Copepoda) Among Captive Mugil and Sparus in Egypt with Reference to Malathion Control

Caligus curtus was involved in an epidemic at a marine fish farm (growing Mugil sp. and Sparus aurafur) in Egypt. Lesions involved erosions, ulcerations, and dark discoloration, especially at the nuchal region. No bacterial growth was obtained from the lesions. The parasite was controlled in ponds with malathion at a concentration of 0.02 ppm. Two successive bath treatments, at 15-day intervals, were effective in treatment of fish.     

Phosphatase activity with reference to bacteria and phosphorus in tropical freshwater aquaculture pond systems

The bio‐geochemical cycle of phosphorus is significantly influenced by microbes in the aquatic environment. Organic phosphorus compounds are decomposed and mineralized by enzymatic complexes such as phosphatases produced by microbes. Enzymatic catalysis results in the production of orthophosphate, which can be used readily by primary producers. Even the smallest concentration of phosphate in water has an influence over the production process in aquaculture systems. Extracellular alkaline phosphatase activity was observed in water and sediment media of aquaculture ponds with different management practices. Heterotrophic bacterial populations as well as phosphatase‐producing bacterial populations were higher in sediments compared with water. In the freshwater fish ponds, Bacillus spp. were the dominant forms of bacteria producing phosphatase. The alkaline phosphatase activity of sediment was always higher than that of water. The partitioning of extracellular alkaline phosphatase in pond water by a 0.22‐µm membrane filter revealed that a proportion was often free rather than cell associated and might have originated as free enzymes released by enriched sediments or by fish or microbes. In the case of water, although the dissolved alkaline phosphatase activity was lower than the total alkaline phosphatase activity, the former was nevertheless unimportant, as it constituted about 20% of the ‘total’ activity. Free alkaline phosphatase activity shared a negative correlation with the orthophosphate concentration of water, whereas gross alkaline phosphatase activity was positively correlated with the total phosphorus and bacterial population of water.     

Efficiency of oxbow lake management systems in Bangladesh to introduce cage culture for resource-poor fisheries

A total of 5488 ha of oxbow lakes in Bangladesh has recently gained importance as a potential fishery resource. The growing need to utilize this resource to a fuller potential requires consideration of cage culture by resource-poor fishing communities as a compliment to existing stock enhancement programmes. In the present study, the existing management systems of eight lakes are reviewed. Water quality was analysed with reference to the largest lake, i.e. Lake Baluhar. During the present study, > 100 cm transparency indicated the suitability of a lake for cage culture. Other water quality parameters, especially dissolved oxygen, ammonia and nitrite concentrations, also indicated suitability for cage culture. Non-fisheries activities, such as the use of agricultural pesticides in the lake catchment and jute retting in its basin, were identified as the most harmful to fish by the majority of the fishermen. An integrated pest management programme using rice–fish based rearing systems in the lake catchment is recommended. It is further recommended that a unified management system should replace the existing dispersed systems under different management bodies.     

Evaluation of membrane filtration and UV irradiation to control bacterial loads in recirculation aquaculture systems

Ultraviolet (UV) irradiation is commonly used to control pathogen loads in recirculation aquaculture systems (RAS), although these micro-organisms can be shielded by particles in the water, and some species tolerate very high UV doses. The objective of this study was to evaluate membrane filtration (MF) as an alternative, or complimentary, treatment to UV irradiation for pathogen control in RAS, as well as examine the operation and cost of each treatment. In a pilot-scale RAS, both MF and UV were used to treat wastewater for 30 days and water samples were collected biweekly and analysed for culturable bacteria, suspended solids, UV transmittance and other parameters. Bacterial control efficiencies were similar between both MF and UV treatments, which removed 99% of total bacteria and 98% of heterotrophic bacteria, respectively. Surface fouling was negligible for the UV while MF required biweekly cleaning to maintain operation. However, MF had the additional benefit of removing 96% of suspended solids, which resulted in increased UV transmittance. Capital and operating costs of MF were similar to UV, but only when MF treated a fraction of the wastewater compared with UV. We conclude that MF represents a potential complimentary technology to enhance UV irradiation, especially to minimise pathogens in RAS that are shielded by particles or tolerate UV.