Fish Welfare Assessment Research Articles

Development of Welfare Protocols at Slaughter in Farmed Fish.

The study investigated fish welfare at slaughter. Killing animals may induce suffering to the animals even under the best available technical conditions. Moreover, fish have different physiological characteristics and are slaughtered differently from terrestrial animals. The use of commercially available methods exposes farmed fish to pain and suffering during slaughter, which could lead to acute stress and post mortem changes in fish quality. The study aimed to discuss (i) the current knowledge and knowledge gaps on fish welfare related to stunning and killing methods; (ii) the variables that affect the post mortem changes in fish meat, and (iii) the indicators of welfare during slaughter. Application of welfare protocols at slaughter improves fish welfare. Specific protocols for fish are not provided in EC Regulation 1099/2009 on animal protection at killing. Detailed guidelines in the fish welfare assessment may allow the development of specific fish legislation. Developing humane technologies might have important effects on fish quality, consumer perception and aquaculture economics.

Exploring Multifunctional Markers of Biological Age in Farmed Gilthead Sea Bream (Sparus aurata): A Transcriptomic and Epigenetic Interplay for an Improved Fish Welfare Assessment Approach.

DNA methylation clocks provide information not only about chronological but also biological age, offering a high-resolution and precise understanding of age-related pathology and physiology. Attempts based on transcriptomic and epigenetic approaches arise as integrative biomarkers linking the quantification of stress responses with specific fitness traits and may help identify biological age markers, which are also considered welfare indicators. In gilthead sea bream, targeted gene expression and DNA methylation analyses in white skeletal muscle proved sirt1 as a reliable marker of age-mediated changes in energy metabolism. To complete the list of welfare auditing biomarkers, wide analyses of gene expression and DNA methylation in one- and three-year-old fish were combined. After discriminant analysis, 668 differentially expressed transcripts were matched with those containing differentially methylated (DM) regions (14,366), and 172 were overlapping. Through enrichment analyses and selection, two sets of genes were retained: 33 showing an opposite trend for DNA methylation and expression, and 57 down-regulated and hypo-methylated. The first set displayed an apparently more reproducible and reliable pattern and 10 multifunctional genes with DM CpG in regulatory regions (sirt1, smad1, ramp1, psmd2-up-regulated; col5a1, calcrl, bmp1, thrb, spred2, atp1a2-down-regulated) were deemed candidate biological age markers for improved welfare auditing in gilthead sea bream.

Histomorphological Changes in Fish Gut in Response to Prebiotics and Probiotics Treatment to Improve Their Health Status: A Review.

The gastrointestinal tract (GIT) promotes the digestion and absorption of feeds, in addition to the excretion of waste products of digestion. In fish, the GIT is divided into four regions, the headgut, foregut, midgut, and hindgut, to which glands and lymphoid tissues are associated to release digestive enzymes and molecules involved in the immune response and control of host-pathogens. The GIT is inhabited by different species of resident microorganisms, the microbiota, which have co-evolved with the host in a symbiotic relationship and are responsible for metabolic benefits and counteracting pathogen infection. There is a strict connection between a fish's gut microbiota and its health status. This review focuses on the modulation of fish microbiota by feed additives based on prebiotics and probiotics as a feasible strategy to improve fish health status and gut efficiency, mitigate emerging diseases, and maximize rearing and growth performance. Furthermore, the use of histological assays as a valid tool for fish welfare assessment is also discussed, and insights on nutrient absorptive capacity and responsiveness to pathogens in fish by gut morphological endpoints are provided. Overall, the literature reviewed emphasizes the complex interactions between microorganisms and host fish, shedding light on the beneficial use of prebiotics and probiotics in the aquaculture sector, with the potential to provide directions for future research.

Calibrating accelerometer data, as a promising tool for health and welfare monitoring in aquaculture: Case study in European sea bass (Dicentrarchus labrax) in conventional or organic aquaculture

Both the conventional and organic aquaculture sectors have grown rapidly over the past few years. Moreover, welfare has attracted increased attention on the part of both consumers and governments. However, fish welfare assessment is complex and thus needs to adapt measurements that are easily applicable to aquaculture conditions. In this study, in addition to classical welfare indicator measurements (physiological stress indicators and growth performance), we recorded the swimming activity data using acoustic transmitters to evaluate the welfare of European sea bass (Dicentrarchus labrax) fed a conventional vs. an organic diet. Prior feeding trial, the swimming activity recorded by tag has been calibrated with water speed during critical swimming speed (Ucrit) tests. This calibration allowed us to increase the power of the recorded data, providing information on swimming activity with respect to the Ucrit value and on the metabolic cost of swimming. After a four-month experimental period, physiological stress indicators and growth performance did not differ significantly between the two diet groups. However, we observed a subtle difference in swimming activity: the fish in the organic diet group were more active during the feeding period in the morning. All indicators considered, our results suggest that an organic diet does not incur higher metabolic costs and does not affect the welfare of the European sea bass. Moreover, this study shows that the use of acoustic transmitters previously calibrated with physiological indicators, such as Ucrit, is a promising tool for welfare monitoring in aquaculture conditions.

Emerging indicators of fish welfare in aquaculture

AbstractAs aquaculture continues to grow and intensify, there is an increasing public concern over the welfare of farmed fish. Stress and production‐related pathologies and repressed growth are examples of the challenges facing aquaculture, and their impacts could be minimised by effective identification of the early signs of impaired welfare. Many welfare monitoring methods have been recommended; however, continuous and reliable welfare monitoring in aquaculture is not yet widespread and commonplace. The aim of this scoping review was to present an overview of the most recent developments in fish welfare assessments with a specific focus on practical translation to the aquaculture industry. A keyword‐based search was undertaken to identify peer‐reviewed papers published between 2014 and 2020 in which a novel method with the potential to be used for the assessment of fish welfare in aquaculture was introduced. The results were sorted into two categories: non‐invasive and invasive methods. All methods were assessed for their advantages and disadvantages, potential applicability to aquaculture. Invasive methods were also ranked on their degree of impact. It is concluded that increased interest into fish welfare, in combination with more intelligent modern technology, has resulted in the development of newer and more refined alternatives to traditional methods of welfare assessment such as behaviour monitoring by 2D cameras and plasma cortisol evaluation. Although, in many cases, more research is needed before these methods are suitable for widespread industry use, studies that focus on increasing the precision, automation and practical applicability of these methods are a promising avenue for future research.

Animal Welfare Issues in Capture-Based Aquaculture.

Simple SummaryAquaculture is about farming aquatic animals in certain facilities, in order to meet the global demand for aquatic animal products. However, reproduction and raising of all commercially important aquatic animals under farming conditions are not always feasible or cost-effective. Thus, for some fish and shellfish species, a system that relies on the collection of wild individuals, at various life stages and rearing in controlled facilities, has been employed. These animals, however, are not products of a lengthy domestication process and thus are not used to the artificial environment of the fish farms. The way they respond to the various stressful conditions might be different, compared to the domesticated fish. Therefore, we have to make sure that we use the appropriate rearing methods, for the entire time, so that their impact on the fish welfare is minimized. Apart from the moral obligations, this will also increase the profitability of the activity.Capture-based aquaculture (CBA) represents a type of intensive aquaculture production system for some economically valuable fish species, such as bluefin tuna (Thunnus thynnus), eel (Anguilla spp.) and Atlantic cod (Gadus morhua). In CBA, fish are captured from the wild in certain periods of the year, and following a recovery phase, they are kept in rearing facilities for a period of time, until they reach the market size. In this case, the fish are wild and have not gone through domestication like other fish species that are reproduced and farmed under the established farming systems. Therefore, these fish are not genetically adapted to live under the intensive farming conditions, and thus their welfare may be compromised in different manners compared to their domesticated counterparts. This review presents an overview of the current situation of CBA, while focusing on the assessment of fish welfare in CBA. The most commonly used fish welfare indicators will be discussed in relation to the different stages of CBA.

Blood Will Tell: What Hematological Analyses Can Reveal About Fish Welfare.

Blood analyses provide substantial information about the physiological aspects of animal welfare assessment, including the activation status of the neuroendocrine and immune system, acute and long-term impacts due to adverse husbandry conditions, potential diseases, and genetic predispositions. However, fish blood is still not routinely analyzed in research or aquaculture for the assessment of health and/or welfare. Over the years, the investigative techniques have evolved from antibody-based or PCR-based single-parameter analyses to now include transcriptomic, metabolomic, and proteomic approaches and from hematological observations to fluorescence-activated blood cell sorting in high-throughput modes. The range of testing techniques established for blood is now broader than for any other biogenic test material. Evaluation of the particular characteristics of fish blood, such as its cell composition, the nucleation of distinct blood cells, or the multiple isoforms of certain immune factors, requires adapted protocols and careful attention to the experimental designs and interpretation of the data. Analyses of fish blood can provide an integrated picture of the endocrine, immunological, reproductive, and genetic functions under defined environmental conditions and treatments. Therefore, the scarcity of high-throughput approaches using fish blood as a test material for fish physiology studies is surprising. This review summarizes the wide range of techniques that allow monitoring of informative fish blood parameters that are modulated by different stressors, conditions, and/or treatments. We provide a compact overview of several simple plasma tests and of multiparametric analyses of fish blood, and we discuss their potential use in the assessment of fish welfare and pathologies.

MyFishCheck: A Model to Assess Fish Welfare in Aquaculture.

Simple SummaryWelfare is a key aspect in animal husbandry. However, in aquaculture, scientifically validated and practically proven methods to evaluate fish welfare are largely missing. With raising societal requirements for animal-friendly husbandry, this lack represents a problem for farmers and scientists alike. We therefore developed MyFishCheck, a comprehensive model and a user-friendly app to assess and document welfare as part of the working routines in fish husbandry. The app enables an easy and standardised measurement of relevant, practicable and reliable parameters, from which the model calculates intuitive welfare grades. Both the model and the app are explicitly designed to be adaptable to new knowledge and any fish species and husbandry system. MyFishCheck allows a standardised evaluation and digital documentation of fish welfare. As a result, improvements can be tracked and problems identified early. We hope that MyFishCheck proves to be a useful tool for fish farmers and supports them in their effort to improve welfare in aquaculture.Welfare in animal husbandry includes considerations of biology, ethics, ecology, law and economics. These diverse aspects must be translated into common quantifiable parameters and applicable methods to objectively assess welfare in animals. To assist this process in the field of aquaculture, where such methods are largely missing, we developed a model to assess fish welfare. A network of information was created to link needs, i.e., fundamental requirements for welfare, with parameters, i.e., quantifiable aspects of welfare. From this ontology, 80 parameters that are relevant for welfare, have practicable assessment methods and deliver reliable results were selected and incorporated into a model. The model, named MyFishCheck, allows the evaluation of welfare in five distinct modules: farm management, water quality, fish group behaviour, fish external and fish internal appearance, thereby yielding five individual grades categorising welfare ranging from critical, to poor, to acceptable, and good. To facilitate the use of the model, a software application was written. With its adaptability to different fish species, farming systems, regulations and purposes as well as its user-friendly digital version, MyFishCheck is a next step towards improved fish welfare assessment and provides a basis for ongoing positive developments for the industry, the farmers and the fish.

Evaluation of the Effects of the Enriched-Organic Diets Composition on European Sea Bass Welfare through a Multi-Parametric Approach

Three groups of European sea bass (Dicentrarchus labrax) were fed for seven months, with either a conventional diet or two different organic diets, which contain organic vegetables and a natural antioxidant compound. The two organic diets differed themselves in terms of raw proteins, fish oil, and lipid contents. Sea bass welfare condition was assessed in relation to these three diets, using 16 different indicators. These were: swimming activity (recovery test, muscle activity), haematological and serological stress indicators (haematocrit, haemoglobin, red-blood-cell count, cortisol, glucose, lactate), aspecific immunity parameter (lysozyme), indicators of exposure to organic contaminants (7-ethoxyresorufin-O-deethylase and glutathione-S-transferase), and growth parameters (weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio, and hepato-somatic index). Most of these parameters individually did not give consistent responses, but their integration can provide an accurate evaluation of the fish welfare conditions among the three diet experimental groups. The multiparametric approach outlined a comprehensive picture of sea bass physiological state. The principal component analysis and the multi-criteria-decision-analysis were found to be useful tools for an integrated fish welfare assessment, highlighting that the best welfare condition was achieved in the experimental group fed with the protein-rich organic diet.

Stress Response System in the Fish Skin-Welfare Measures Revisited.

The skin of vertebrates acts as a biological barrier defending the organism against many harmful environmental factors. It is well established that the main stress hormone cortisol, together with antioxidants such as melatonin (Mel) and its biologically active metabolites set up a local stress response system in the mammalian skin. Recently, our research group has shown that in fish there are basic conditions for the functioning of a cutaneous stress response system (CSRS) similar to that in mammals, where Mel with its biologically active metabolite AFMK (N1-acetyl-N2-formyl-5-methoxykynuramine) and cortisol act together to protect organism against unfavorable environment. Since aquaculture is making an increasing contribution to the global economy and new laws are demanding people to respect the welfare requirements of animals there has been increasing interest in indicators of fish well-being in aquaculture. This article addresses the problem of on-farm assessment of fish welfare and proposes the CSRS as a new source of information on the welfare status of farmed fish.

Welfare Challenges Influence the Complexity of Movement: Fractal Analysis of Behaviour in Zebrafish

The ability to assess welfare is an important refinement that will ensure the good condition of animals used in experimentation. The present study investigated the impact of invasive procedures on the patterns of movement of zebrafish (Danio rerio). Recordings were made before and after fin clipping, PIT tagging and a standard pain test and these were compared with control and sham handled zebrafish. The fractal dimension (FD) from the 3D trajectories was calculated to determine the effect of these treatments on the complexity of movement patterns. While the FD of zebrafish trajectories did not differ over time in either the control or sham group, the FDs of the treatment groups reduced in complexity. The FD of fish injected with different strengths of acetic acid declined in a dose-dependent manner allowing us to develop an arbitrary scale of severity of the treatments. The 3D trajectory plots from some groups indicated the presence of repetitive swimming patterns akin to stereotypical movements. When administered with lidocaine, which has analgesic properties, the movement complexity of fin clipped fish reverted to a pattern that resembled that of control fish. Fractal analysis of zebrafish locomotion could potentially be adopted as a tool for fish welfare assessment.

A novel emotional and cognitive approach to welfare phenotyping in rainbow trout exposed to poor water quality

Recent scientific evidence for fish sentience has stressed the need for novel sentience-based detection tools of fish welfare impairment in commercial farms. In order to mimic a well-characterised stress situation, rainbow trout (Oncorhynchus mykiss) were exposed to poor water quality (hypoxia combined with high ammonia level) for three weeks (stressed group, S) and compared to a non-stressed control group (NS). After a return to water quality standard, emotional responses were assessed in fish subjected to two potentially threatening situations: (i) social isolation in a novel environment and (ii) human presence. In addition, we used an appetitive-conditioning paradigm to determine whether previous chronic deterioration of water quality disturbs cognitive abilities in fish. Spontaneous behaviour in the tanks was also recorded during the environmental challenge as a reference for fish activity. We observed that in S fish, plasma cortisol levels were increased before and after social isolation in a novel environment compared to the plasma cortisol levels in the NS group, despite the absence of a behavioural difference between the two groups. Under deteriorated water quality, fish locomotor activity was globally reduced and this reduction was correlated to increased shoaling behaviour. Farmers can use these first behavioural modifications as a sentinel detector for fish welfare impairment. More importantly, we demonstrated that reactivity to a human presence in a home-environment and food-anticipatory behaviour were both inhibited in the S group. We consider that these two sentience-based tests are highly relevant for fish welfare assessment at the group level and are easy to use in the aquaculture industry.

Factors Affecting Fin Damage of Farmed Rainbow Trout

Abstract The aims of this study were to determine the influence of the factors affecting fin damage under different rainbow trout production systems and to compare the findings with the known experimental reports. The study was based on a questionnaire that included information about the main factors i.e. oxygen level in exit water, water temperature, stocking density, daily feed ration, number of meals and grading frequency on seven rainbow trout farms. Standard multiple regression analysis, based on a previously published fin damage dataset, was used to assess the relationship between the level of fin damage per fin and the factors. Daily feed ration received the strongest weight in the model for the caudal, anal and both pectoral fins, whereas number of meals received the strongest weight in the model for both pelvic fins. Grading frequency received the strongest weight only in the dorsal fin model. Lower levels of daily feed ration and number of meals combined with higher water temperature increased the level of fin damage, whereas stocking density had no effect. The results conform to the experimental research on fin damage in rainbow trout. The research model contributes to the overall assessment of fish welfare and the regression analysis used in this study could be used on rainbow trout farms to evaluate the effect of the main factors on the level of fin damage.

Salmon welfare index model 2.0: an extended model for overall welfare assessment of caged Atlantic salmon, based on a review of selected welfare indicators and intended for fish health professionals

AbstractHere, we present an extended version of a semantic model for overall welfare assessment of Atlantic salmon reared in sea cages. The model, called SWIM 2.0, is designed to enable fish health professionals to make a formal and standardized assessment of fish welfare using a set of reviewed welfare indicators. SWIM 2.0 supplements SWIM 1.0, which was designed for application by fish farmers. We searched the literature for documented welfare indicators that could be used by fish health professionals. The selected indicators are eyes, cardiac condition, abdominal organs, gills, opercula, skeletal muscles, vaccine‐related pathology, aberrant fish, necropsy of the dead fish and active euthanasia. Selection criteria for the SWIM 2.0 indicators were that they should be practical and measureable on salmon farms by fish health professionals and that each indicator could be divided into levels from good to poor welfare backed up by relevant scientific literature. To estimate each indicator's relative impact on welfare, all the indicators were weighted based on their respective literature reviews and according to weighting factors defined as part of the semantic modelling framework. This was ultimately amalgamated into an overall SWIM 2.0 model that can be used to calculate welfare indexes for salmon in sea cages, taking into account the available fish health expertise. Using this model, an example calculation based on recordings and samplings done from an Atlantic salmon sea cage containing 106 000 fish yielded an overall welfare index of 0.81 of a maximum of 1.0.

Salmon Welfare Index Model (SWIM 1.0): a semantic model for overall welfare assessment of caged Atlantic salmon: review of the selected welfare indicators and model presentation

AbstractA semantic model for overall welfare assessment of Atlantic salmon reared in sea cages is presented. The model, called SWIM 1.0, is designed to enable fish farmers to make a formal and standardized assessment of fish welfare using a set of selected welfare indicators. In order to cover all welfare relevant aspects from the animals’ point of view and to create a science‐based tool we first identified the known welfare needs of Atlantic salmon in sea cages and searched the literature for feasible welfare indicators. The framework of semantic modelling was used to perform a structured literature review and an evaluation of each indicator. The selected indicators were water temperature, salinity, oxygen saturation, water current, stocking density, lighting, disturbance, daily mortality rate, appetite, sea lice infestation ratio, condition factor, emaciation state, vertebral deformation, maturation stage, smoltification state, fin condition and skin condition. Selection criteria for the indicators were that they should be practical and measureable on the farm, that each indicator could be divided into levels from good to poor welfare backed up by relevant scientific literature. To estimate each indicator’s relative impact on welfare, all the indicators were weighted based on their respective literature reviews and according to weighting factors defined as part of the semantic modelling framework. This was ultimately amalgamated into an overall model that calculates welfare indexes for salmon in sea cages. More importantly, the model identifies how each indicator contributes (negatively and positively) to the overall index and hence which welfare needs are compromised or fulfilled.

Principles of fish welfare assessment in farm rearing conditions

For several decades fish welfare has been subject of many researches, and the interest for this subject is connected with the fact that fish can feel pain and suffering. In addition to this stressors? mechanisms of action and their consequences are similar in mammals and fish. Assessment of welfare for farmed fish is based on the same principles as for terrestrial farm animals. However, special methods of collecting data are needed due to morphological characteristics of fish and properties of their environment. In the world and in our country, researches of different ways of fish welfare assessment are being conducted, especially based on non-invasive techniques such as monitoring of behaviour. In this paper a review of basic principles and methods used in assessment of farmed fish welfare is given.

The blood biochemical profile as an objective welfare indicator in a sturgeon farm.

Biochemical profile is, along with water quality, an indicator for fish welfare assessment, revealing their level of stress. For establishing blood biochemical profile there were taken blood samples from female and male sturgeons by caudal vein puncture with ventral point of election. Determinations were made with 8008 Vettest device and interpretation of results was done according to reference values in the literature. The obtained results (increased alanin aminotransferase - ALT and alkaline phosphatase, decreased glucose and magnesium), shows that sturgeon welfare in the farm is medium.

Researches Regarding Serum Biochemical Parameters as an Indicator of Fish Welfare in Two Farms from the Southern Area of the Country

The present study aims the assessment of fish welfare in two farms from the southern area of Romania (Ulmu and Ciocanesti) using as objective welfare indicator the serum biochemical profile. The tests were conducted by using Vettest 8008 Chemistry, being analyzed: blood urea nitrogen, creatinine, phosphatemia, calcium, albumine, cholesterol, glucose, total proteins, blood ammonia, alanine transaminase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, total bilirubin, creatin kinase, triglycerides, amylase. The obtained results were compared with those from other scientific researches regarding carp serum biochemical profile. The values in Ciocanesti ponds show increased creatinine, aspartate aminotransferase, phosphatemia, lactate dehydrogenase, alkaline phosphatase values and a slightly increased calcium and albumine values, the cause being the dehydration and the intense muscular effort associated with fish angling and restraining. In Ulmu ponds, there is noticed in adition a significant increasing of cholesterol, transaminases and glucose, which could suggests hepatopancreatic disorders. Following the researches, the fish welfare level was acceptable in Ciocanesti farm and poor in Ulmu.

Researches on fish welfare assessment in Fundulea-Frunzareni farm, based on water quality and blood biochemical parameters.

In order to exist, fish need an appropriate environment, which satisfy its biological necessities. The physical-chemical water conditions play an important role in aquatic organisms' evolution. In Fundulea-Frunzareni fish farm there were harvested water and blood samples. From water samples there were established the physical-chemical parameters as: pH, dissolved oxygen, ammonia, nitrates, nitrites, phosphates, residual chlorine, total ferrum, sulphates and detergents and from serum samples: blood urea nitrogen, creatinine, phosphorum, calcium, albumins, alanine transaminase, cholesterol, tryglicerids, glucose, lactate dehydrogenase. The samples, both water and blood serum, were processed in the Animal welfare discipline laboratory-Faculty of Veterinary Medicine Bucharest, using Nova 60 device for water samples and Vettest 8008 biochemistry analyzer for serum samples. Regarding water quality in Fundulea-Frunzareni fish farm it was found that water pH, dissolved oxygen, ammonia, nitrites, total ferrum and copper recorded values within the admitted limits for carp rearing. Phosphates exceeded the admitted limits provided for carp rearing by 1.5 times in the samples harvested from 3 m depth at the water supplying sector of the pond and by 4 times in rejection sector. Residual chlorine exceeded admitted limits by 6-13 times, depending on the sampling point and depth.

Researches on Fish Welfare Assessment in Fundulea-Frunzareni Farm, Based on Water Quality and Blood Biochemical Parameters

In order to exist, fish need an appropriate environment, which satisfy its biological necessities. The physical - chemical water conditions play an important role in aquatic organisms' evolution. In Fundulea - Frunzareni fish farm there were harvested water and blood samples. From water samples there were established the physical - chemical parameters as: pH, dissolved oxygen, ammonia, nitrates, nitrites, phosphates, residual chlorine, total ferrum, sulphates and detergents and from serum samples: blood urea nitrogen, creatinine, phosphorum, calcium, albumins, alanine transaminase, cholesterol, tryglicerids, glucose, lactate dehydrogenase. The samples, both water and blood serum, were processed in the Animal welfare discipline laboratory - Faculty of Veterinary Medicine Bucharest, using Nova 60 device for water samples and Vettest 8008 biochemistry analyzer for serum samples. Regarding water quality in Fundulea - Frunzareni fish farm it was found that water pH, dissolved oxygen, ammonia, nitrites, total ferrum and copper recorded values within the admitted limits for carp rearing. Phosphates exceeded the admitted limits provided for carp rearing by 1.5 times in the samples harvested from 3 m depth at the water supplying sector of the pond and by 4 times in rejection sector. Residual chlorine exceeded admitted limits by 6-13 times, depending on the sampling point and depth.