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1.
Mortality has received insufficient attention as a fish welfare topic. Here, we aim to prompt fish farming stakeholders to discuss fish mortalities in relation to welfare. Mortality in farmed fish populations is due to a variety of biotic and abiotic causes, although it is often difficult to differentiate between underlying and immediate causes of mortality. Most mortality appears to occur during episodes associated with disease outbreaks and critical periods (in development or production). Most causes of mortality can be assumed to be associated with suffering prior to death. As mortality rates in farmed fish populations are suspected to rank amongst the highest in commonly farmed vertebrate species, mortality should be a principal fish welfare issue. Long-term mortality rates can be used as a retrospective welfare performance indicator and short-term mortality rates as an operational welfare indicator. Scrutiny of mortality records and determining causes of death will enable action to be taken to avoid further preventable mortality. The welfare performance of fish farms should only be judged on levels of predictable and preventable mortality. Fish farmers will already be monitoring mortality due to commercial and legal requirements. As profitability in fish farming is directly linked to survival, confronting mortality should ultimately benefit both fish and farmers.  相似文献   

2.
Abstract. The epidemiology of epizootic haematopoietic necrosis virus (EHNV) infection was studied in farmed rainbow trout, Oncorhynchus mykiss (Walbaum). Estimates of mortality during five outbreaks on a commercial farm from 1986 to 1992 ranged from 0033 to 0.2% per day and total mortality did not exceed 3–4% in any outbreak. Affected fish were 0+ and less than 125 mm forklength. Clinical signs were non-specific, and laboratory examination was required to confirm the diagnosis. At the height of the outbreak in 1992, EHNV was demonstrated by virus isolation and antigen capture ELISA in 89% of clinically affected fish and 51% of dead fish, while the prevalence of infection in apparently healthy in-contact fish was 4%. Two and 4 months later the virus was not detected in a group of apparently healthy fish that had been affected earlier. Antibodies specific for EHNV were not found in rainbow trout from the infected farm; however, strong humoral responses were detected by ELISA in two immunized fish, indicating that the virus was immunogenic. These data suggested that EHNV was poorly infective but highly virulent in rainbow trout. Clinical EHNV infection was positively correlated with high rearing density and a low rate of water exchange, and therefore, with presumed poor water quality. Water temperature, which ranged from 11 to 17°C during outbreaks, did not appear to determine the incidence of clinical infection. EHNV infection in farmed rainbow trout was preceded by infection in free-living redfin perch, Perca fluviatilis L., in the water catchment, but it was uncertain whether this represented the source of infection for rainbow trout.  相似文献   

3.
亚东鲑(Salmo trutta fario)是鲑属鱼类在青藏高原仅有的鱼类种群,是亚东地区全国农产品地理标志产品。本研究对西藏亚东地区野生和养殖亚东鲑的常规营养成分及各组织氨基酸和脂肪酸组成进行分析,旨在比较野生和养殖亚东鲑营养成分的异同,为养殖亚东鲑的品质评价和饲料配方的完善提供参考信息。实验采集亚东河中野生亚东鲑和亚东渔业产业园中使用配合饲料养殖的亚东鲑各10尾用于相关成分分析,每尾为一个独立样本。结果显示,野生组肥满度显著低于养殖组,而全鱼水分和灰分显著高于养殖组。全鱼粗蛋白、粗脂肪以及肝脏常规成分在野生组和养殖组间无显著差异。野生组肌肉粗脂肪显著低于养殖组,而水分含量显著高于养殖组。野生组全鱼必需氨基酸总量显著高于养殖组,且野生组肌肉中苏氨酸、缬氨酸、苯丙氨酸、赖氨酸和甘氨酸含量显著高于养殖组。野生组全鱼、肌肉和肝脏中饱和脂肪酸、n-3多不饱和脂肪酸(n-3 PUFA)总量、EPA、C20:4n-6以及肌肉中DHA含量高于养殖组,而全鱼和组织中单不饱和脂肪酸和n-6 PUFA总量低于养殖组。综上所述,目前养殖亚东鲑和野生亚东鲑在机体成分上存在较大差异。由于养殖鱼类体成分很大程度上反映了饲料组成,因此,亚东鲑养殖中饲料营养组成可能有待进一步优化。  相似文献   

4.
Abstract. The food of brown trout, Salmo trutta L., and rainbow trout, Oncorhynchus mykiss (Walbaum). in a small stillwater put-and-take fishery in Surrey, England was examined by stomach content analysis of fish caught by angling between the months of April and September 1985. Overall, brown and rainbow trout tended to utilize different food sources. Mann-Whitney U-tests showed most major food items to be eaten in significantly different amounts, the most important exceptions being chironomid pupae and adult Diptera. In all months except April, rainbow trout utilized mainly midwater food, particularly Cladocera. Brown trout fed mainly on benthic food organisms and fish. Spearman rank correlations showed diets to be dissimilar during this period, with significant negative correlations in May and August. These results indicate an absence of interspecific competition for food, and imply spatial separation of brown and rainbow trout. In April both brown and rainbow trout fed extensively on the temporary bottom fauna, mainly trichopteran and megalopteran larvae, and diets were significantly positively correlated.  相似文献   

5.
Fish welfare at harvest is easily compromised by poor choice of handling and slaughter methods, lack of attention to detail and by unnecessary adherence to fish farming traditions. The harvest process comprises fasting the fish to empty the gut, crowding the fish, gathering and moving the fish using brails, fish pumps, and sometimes also road or boat transport and finally stunning and killing the fish. The harvesting processes commonly used for bass, bream, carp, catfish, cod, eel, halibut, pangasius, salmon, tilapia, trout, tuna and turbot are outlined. These harvesting processes are discussed; the consequences for fish welfare identified and practical tests which can be made at the harvest site highlighted. Welfare at harvest for the majority of farmed fish species can be improved by adopting and adapting existing procedures already known to be beneficial for fish welfare through their use in other fish farming systems or with other species. It is seldom necessary to develop completely new concepts or methods.  相似文献   

6.
The objective was to take a first step in the development of a process-oriented quality assurance (QA) system for monitoring and safeguarding of fish welfare at a company level. A process-oriented approach is focused on preventing hazards and involves establishment of critical steps in a process that requires careful control. The seven principles of the Hazard Analysis Critical Control Points (HACCP) concept were used as a framework to establish the QA system. HACCP is an internationally agreed approach for management of food safety, which was adapted for the purpose of safeguarding and monitoring the welfare of farmed fish. As the main focus of this QA system is farmed fish welfare assurance at a company level, it was named Fish Welfare Assurance System (FWAS). In this paper we present the initial steps of setting up FWAS for on growing of sea bass (Dicentrarchus labrax), carp (Cyprinus carpio) and European eel (Anguilla anguilla). Four major hazards were selected, which were fish species dependent. Critical Control Points (CCPs) that need to be controlled to minimize or avoid the four hazards are presented. For FWAS, monitoring of CCPs at a farm level is essential. For monitoring purposes, Operational Welfare Indicators (OWIs) are needed to establish whether critical biotic, abiotic, managerial and environmental factors are controlled. For the OWIs we present critical limits/target values. A critical limit is the maximum or minimum value to which a factor must be controlled at a critical control point to prevent, eliminate or reduce a hazard to an acceptable level. For managerial factors target levels are more appropriate than critical limits. Regarding the international trade of farmed fish products, we propose that FWAS needs to be standardized in aquaculture chains. For this standardization a consensus on the concept of fish welfare, methods to assess welfare objectively and knowledge on the needs of farmed fish are required.  相似文献   

7.
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8.
The welfare of farmed fish has attracted attention in recent years, which has resulted in notable changes within the aquaculture industry. However, a lack of communication between stakeholders and opposing ethical views are perceived as barriers to achieving consensus on how to improve farmed fish welfare. To address these issues, we developed an interactive approach that could be used during stakeholder meetings to (1) improve communication between different stakeholder groups, (2) build consensus on priorities for farmed fish welfare and (3) establish mechanisms to address welfare priorities. We then applied this approach during a meeting of stakeholders to identify current and future priorities for farmed fish welfare in the UK. During the meeting in the UK, stakeholders initially identified 32 areas that they felt were in need of development for future improvements in farmed fish welfare. These were further refined via peer review and discussion to the seven most important “priority” areas. Establishing a “better understanding of what good fish welfare is” emerged as the highest priority area for farmed fish welfare. The second highest priority area was “the need for welfare monitoring and documentation systems”, with mortality recording proposed as an example. The other five priority areas were “[improved understanding of] the role of genetic selection in producing fish suited to the farming environment”, “a need for integration and application of behavioural and physiological measures”, “the need for a more liberal regime in Europe for introducing new medicines”, “a need to address the issues of training existing and new workers within the industry”, and “ensuring best practise in aquaculture is followed by individual businesses”. Feedback from attendees, and the meeting outputs, indicated that the approach had been successful in improving communication between stakeholders and in achieving consensus on the priorities for farmed fish welfare. The approach therefore proved highly beneficial for future improvements in fish welfare in the UK.  相似文献   

9.
Abstract. Salmonid fish at fish farms in northern and central Finland and perch, Perca fluviatilis L., roach, Rutilus rutilus (L.), and whitefish, Coregonus sp., from four lakes in central Finland were studied between 1985 and 1990 for the occurrence of Yersinia ruckeri. The bacteria were found in fish from both areas, but in most cases, only single diseased salmon, Salmo salar L., brown trout, S. trutta L., rainbow trout, Oncorhynchus mykiss (Walbaum), whitefish and perch were encountered and were always connected with stress conditions. One clinical outbreak occured in salmon fingerlings in northern Finland, and the fish were successfully treated with trimethoprim-sulpha. Monthly monitoring of lake fish revealed two symptomless carrier perch in two lakes. Outwith the main study a moribund perch with yersiniosis was found in a polluted lake, and for the first time in Finland, a rainbow trout was also found to have contracted yersiniosis in a small private pond. Sorbitol-positive and negative isolates have been found to occur in both moribund and carrier farmed fish, indicating that the sorbitol test is not essential when evaluating the pathogenicity of Y. ruckeri.  相似文献   

10.
Welfare in farmed fish got particular attention during the last decades from both governmental and public sides. In aquaculture context, welfare concerns are mainly related to handling procedures, water quality and stoking densities. In Europe, authorities had to clarify the threshold limits of stocking densities to maintain fish good welfare, including for organics aquaculture through the EC regulation 710/2009. However, effects of stocking density on fish welfare are complex and sometimes contradictory. Moreover, there is a lack of knowledge about the impact of density on fish welfare in organic aquaculture. Thus, the aim of the study is to asses welfare state of rainbow trout (Oncorhynchus mykiss) at two initial stocking densities (low density, LD: 12 kg/m3 and high density, HD: 17 kg/m3) fed using organic feed by combining the monitoring of growth performances, behaviour (swimming activity) and physiological indicators (i.e. cortisol, glucose, lactate, hematocrit, red blood cellule count and lysozyme). At the end of experiment, the stocking density reached 21 kg/m3 and 30 kg/m3 for the LD and HD respectively. Overall, growth performances, swimming activity and level of physiological indicators of stress and welfare were similar between HD and LD over the experiment duration. To conclude, we observed no alteration of fish welfare between the two stocking densities monitored. This study suggests that a final stocking density of 30 kg/m3 can be considered for organic aquaculture of rainbow trout respecting welfare.  相似文献   

11.
Nile tilapia (Oreochromis niloticus) is currently one of the most farmed freshwater fish and contributes significantly to total global aquaculture production. The genetically improved strain of O. niloticus (GIFT) was introduced to Papua New Guinea (PNG) in 1999 to improve food and income security. The high cost and low availability of commercial fish feed hinder the growth of GIFT farming in PNG. Stable carbon and nitrogen isotopes were used to determine the role of supplementary and natural food sources in the diet of GIFT in pond‐based aquaculture. Two treatments were used: treatment 1 was daily feeding, and treatment 2 was weekly feeding, each with three replicates. Isotopic analysis of muscle tissue and all potential food sources showed that pellet feed contributed 7% to the growth of GIFT in daily‐fed ponds and 33% in the weekly‐fed ponds. Highly enriched δ15N values for chicken manure, compared to depleted values for GIFT and other natural food sources in both treatments, clearly indicate insignificant contributions of this input to production. After 90 days of cultivation, the average final body weight of GIFT receiving daily feed inputs was 134 g (average 19 cm), while for weekly‐fed it was 92 g (17 cm). The feed conversion ratio (FCR) was poor (6.4:1) in the daily‐fed GIFT ponds compared to a better, and preferable, FCR (1:1) in the weekly‐fed ponds. The findings of this study show that pelleted feed was not the major contributor to the growth of GIFT. Genetically improved farmed tilapia aquaculture should focus on enhancing natural food availability for fish production.  相似文献   

12.
We conducted a 12-week feeding trial with largemouth bass (LMB) to examine the interactive effects of non-fish dietary proteins with different lipid sources on the performance of LMB (3.4 g ± 0.05 g). Practical diets contained poultry by-product meal (PBM) in place of fish meal on a digestible-protein basis, and 12% blood meal (BM). Diets were supplemented with 10% lipid as canola (CAN), chicken (CHK), CHK + MFO (50 : 50), menhaden fish oil (MFO) or CHK + CAN (50:50). A commercial trout diet (SC) was included as a positive control. Growth, survival, feed intake (FI), feed conversion ratio (FCR), protein efficiency ratio (PER), body composition, fatty acid composition of liver and muscle, hematological parameters and lysozyme and alternative complement activity (ACH50) were measured to assess diet effects. Weight gain (23.8 ± 1.8 g), survival (92 ± 4%), FI (44.3 ± 4.1 g), FCR (2.1 ± 0.1) and PER (1.3 ± 0.04) of LMB did not differ among the replacement diets. However, weight gain (38.5 ± 1.5), FI (53.9 ± 1.1), and PER (1.6 ± 0.1) of LMB fed the SC diet was higher and FCR (1.4 ± 0.1) was lower than that of fish fed the test diets. No signs of essential fatty acid deficiency were observed, although tissue concentrations of n-3 highly unsaturated fatty acids declined markedly in LMB fed diets without fish oil. Lymphocytes were elevated in fish fed diets with ≥ 7% n-3 fatty acids. Fish fed diets with 10% MFO or CHK + MFO had higher ACH50 than fish fed the diet with 10% CHK. There were no differences in serum lysozyme activity among fish fed the test diets. Hematocrit, hemoglobin, ACH50, and lysozyme activity were higher in fish fed the SC diet than in those fed the test diets. Regardless of lipid source, the ACH50 and lysozyme activity were greatly reduced in LMB fed PBM diets compared to LMB fed diets with 30% fish meal in a previous trial. The amino acid composition of the PBM was similar to that of fish meal. However, the availability of some essential amino acids from PBM to LMB may have been limited, and poor diet palatability caused by BM also may have reduced feed intake and performance of LMB.  相似文献   

13.
Effective methods of producing instantaneous and irreversible unconsciousness at the time of slaughter are crucial for ensuring animal welfare in commercial aquaculture. However, the traditional method of visually evaluating unconsciousness has been shown to be insufficient and may lead to misjudgements of stunning efficiency. In this study, we developed a non‐invasive technique that measures brain activity in fish as an alternative to traditional invasive, brain implants and used it to determine when a change in consciousness occurs in trout during anaesthesia induction. Nine rainbow trout (Oncorhynchus mykiss) were equipped with a custom designed silicone cup fitted with electrodes and submerged in 10°C water with dissolved MS‐222. During anaesthesia, the state of consciousness was assessed by recordings of electroencephalogram (EEG). The EEG recordings were analysed both by visually evoked responses from light stimulation (VERs) and from changes in signal amplitude, median frequency and relative signal power. According to the loss of VERs and decrease in signal amplitude, trout transitioned to surgical depth of anaesthesia within 5 min. Our results show that consciousness, or loss of, can be determined using a non‐invasive system to record EEG in fish.  相似文献   

14.
This study evaluated the nutritional quality of farmed and wild axillary seabream (Pagellus acarne R., 1827) focusing on amino acid profiles, with regards to possible interactions with wild fish aggregating around the cage facility. Total amino acids (∑AA), essential amino acids (∑EAA), non‐essential amino acids (∑NEAA) and neutral amino acids (∑NAA) in farmed fish were lower than those in the wild individuals (p > .05). Amino acid pattern in cage‐aggregated fish showed a slight decline from the wild populations, but still higher than the farmed fish. Based on the amino acid scores (AAS), lysine and leucine could be underlined as the ‘first limiting amino acids’, but all other AASs were over ‘1’, in accordance with reference amino acid contents of FAO/WHO (>1.00), showing that farmed axillary seabream provides high nutritional quality and can be considered as a favourable protein source. The ratios of ∑EAA/∑AA (44%–46%) and ∑EAA/∑NEAA (79%–86%) exceeded the minimum recommendation of 40% and >60% by FAO/WHO for all three groups. It can be concluded that axillary seabream either farmed, farm‐aggregated or distant wild fish presented high‐quality protein generating a healthy source for human food.  相似文献   

15.
In this study, high throughput 16S rRNA sequencing was used to investigate the effect of a novel whole‐cell dietary microalgae meal (Schizochytrium limacinum), on the distal intestinal microbiome of farmed rainbow trout, Oncorhynchus mykiss. Heterotrophic microalgae are rich in omega 3 polyunsaturated fatty acids, can be produced sustainably and have been shown to have beneficial effects on host health. After a 15‐week trial period, microbial community profiles were compared between the distal intestinal contents of fish fed either a control diet or a treatment diet that partially replaced fish oil with microalgae meal, at a substitution level of 5%. The results of this research showed that the microbial communities of both fish populations were composed of similar microbial taxa, however, the treatment group fed the microalgae supplement possessed a greater level of microbial diversity than those in the control group. A limited number of bacterial taxa were discriminatory between diets and were significantly elevated in the treatment group, notably operational taxonomic units (OTUs) assigned to the genera Streptococcus, Leuconostoc, Lactobacillus, Lactococcus and Weissella. However, the overall structure of the intestinal microbiome between control and treatment groups was not found to be significantly different. The treatment group displayed a heavier mean weight and condition factor at the end of the trial period. The results of this study suggest that the tested microalgae meal can be used as a replacement for a proportion of fish oil in aquafeeds, with minor changes to the intestinal microbiome of farmed rainbow trout, and positive effects on growth.  相似文献   

16.
ABSTRACT

European consumers prefer wild over farmed aquatic food and consider it healthier and tastier. Consumers are increasingly paying attention to sustainability and welfare of farmed fish. Such expectations might be met by organic certification, but this represents a cost for the producer. It is crucial to know consumer habits about farmed aquatic food consumption and willingness to pay for certification. Data about Italian consumers’ preferences regarding farmed organic aquatic food were collected by an online questionnaire. A total of 8,657 answers were analyzed, patterns associated with demographics were investigated, and the degree of correlation among answers was calculated. The majority (75%) of family units buy less than 2 kg of farmed aquatic food per month, spending on average 20–50 €. About 40% never consume organic aquaculture products because of lack of knowledge, unavailability, and high price. Slightly over half (55%) of consumers, regardless of age, sex, and area, were willing to pay a premium price for organic-certified aquatic food, seen as antibiotic free, traceable, and sustainable. Organic food in general is well known, and distrust is the main reason that consumers avoid it, while organic aquatic food is still in its infancy, and lack of knowledge is associated with low consumption.  相似文献   

17.
Wood in streams functions as fish habitat, but relationships between fish abundance (or size) and large wood in streams are not consistent. One possible reason for variable relationships between fish and wood in streams is that the association of fish with wood habitat may depend on ecological context such as large‐scale geomorphology. We studied the relationship between salmonid assemblages and large wood jams (LWJ) in four settings that differed geomorphically at the scale of the stream corridor along a tributary to Lake Superior in old‐growth conifer–hardwood forest in northern Michigan. The focal fish species of this study were brook trout (Salvelinus fontinalis), which were wild in the stream. Relocation efforts for coaster brook trout (an adfluvial life history variant of brook trout) were ongoing in the study stream. We measured fish abundance and length in pairs of pools of similar size and substrate, but varying in the presence of LWJ; this allowed us to evaluate associations of fish simply with the presence of LWJ rather than with other channel or flow‐shaping functions of LWJ. The length of Oncorhynchus spp. and young introduced brook trout was not strongly correlated with LWJ presence; however, the presence of LWJ in pools was positively correlated with larger wild brook trout. We also found that the correspondence of LWJ with the abundance of salmonids appears to be moderated by the presence of alternative habitat in this relatively natural, old‐growth forest stream.  相似文献   

18.
The main hypothesis of this study was that if stomach volume is correlated with food intake it can be estimated without laborious and destructive direct measurement. Rainbow trout, Oncorhynchus mykiss (Walbaum), ca. 500–1300 g, were starved for 1, 4, 8 or 16 days at 15°C after which they were fed in excess with dry pellets containing known amounts of X‐ray‐dense markers. Immediately after feeding the fish were killed, X rayed and weighed. Then the stomach was dissected, its contents removed and weighed, and stomach volume was measured. X‐ray plates were developed and feed intake was estimated based on the amount of marker. All measured variables correlated positively with stomach volume. The best fit for linear regression models was obtained for fish starved for 4 days, where stomach content (dry mass) explained 94%, food intake (based on X‐ray measurement) 77% and fish mass 62% of the variation in stomach volume. However, as stomach content measurement can be a lethal, or at least very stressful, event for the fish, the accuracy of food intake measurement (X‐ray) could be increased using multiple regression. In multiple linear regressions, R2‐values varied between 0.79 (16‐day starvation) and 0.91 (1‐day starvation) with food intake and fish mass as explanatory variables for stomach volume. These results indicate that the stomach volume in rainbow trout can be estimated satisfactorily using indirect methods, which are not detrimental to the fish, although feeding history may affect the accuracy of the estimates.  相似文献   

19.
The oxidative status is associated with animal lifespan, metabolism, activity and circadian rhythms. The objective of this work is to study the time course of the oxidative status over a daily cycle in the plasma, liver and brain, and the changes in the plasma cortisol levels of sturgeon and trout. The knowledge of daily oxidative status will provide a better understanding of the trout and sturgeon physiology and adequate maintenance and food supply of farmed fish in relation to photoperiod. Superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione transferase, DT-diaphorase activities, lipid peroxidation and cortisol were measured. Our results showed that the antioxidative enzyme activities and lipid peroxidation in the liver of trout and sturgeon changed through the day, with increased levels in lipid peroxidation of liver in the dark period for sturgeon. This could be related to the different activity time in both species, an issue to be taken into account when designing the guidelines of the maintenance of these species in fish farms. On the contrary, there was not clear influence of the daily rhythms on brain oxidative status. The higher efficiency of the antioxidant defences in the brain of sturgeon, which displays less lipid peroxidation and higher antioxidative activity, could be related to its longer life expectancy. The absence of any apparent daily rhythm in the plasma cortisol levels in sturgeon could indicate a lower susceptibility to stress, and that mechanisms involved in cortisol secretion in chondrosteans could be different from that described for teleosteans.  相似文献   

20.
采用主成分分析方法评价泥鳅Misgurnus anguillicaudatus、黄鳝Monopterus albus、鲫Carassius auratus、鲤Cyprinus carpio、乌鳢Channa argus、黄颡鱼Pelteobagrus fulvidraco,和虹鳟Oncorhynchus mykiss等7种常见食用鱼的食用品质价值,对其17种氨基酸进行综合评价。通过建立鱼类食用品质评价模型,构造综合评价函数计算综合得分并排序,来反映该种鱼类的食用品质。结果显示:虹鳟综合得分最高,其次是鲫,而黄颡鱼排在最末。通过主成分分析模型建立可量化的评价指标和新的评价方法,为鱼类营养价值评价提供更为准确、客观的方法。  相似文献   

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