Farmed Species Research Articles

Surveying the welfare of farmed fish species on a global scale through the fair-fish database.

Fish welfare is a critical issue that needs to be addressed by the rapidly growing aquaculture industry. Scientific knowledge regarding the natural behaviors of species and the conditions in which they are kept in farms is essential for improving their welfare in aquaculture. To provide a consistent overview of the welfare of farmed fish, the organization fair-fish has created the online platform fair-fish database, which gathers ethological knowledge categorized into profiles of farmed aquatic species. The WelfareChecks on this platform are profiles based on criteria that are rated based on the likelihood and potential of the species to experience a high level of welfare in aquaculture systems, together with the certainty about the findings. A score (WelfareScore) is calculated from these ratings, serving as a reference to identify knowledge gaps, assess welfare, and suggest ways to improve it. Here, we performed an in-depth analysis of the species with WelfareChecks already published in the fair-fish database based on their respective WelfareScores. In general, although just a small percentage of farmed aquatic species (~5%) have at least a 20% chance of experiencing a good level of welfare under minimal aquaculture conditions, 60% of them have at least some potential to achieve good welfare under high-standard conditions, with more than a third of the species (~37%) having at least a 20% potential. Despite that, several species exhibit a very high frequency of low chances and potential for experiencing good welfare levels under aquaculture conditions, besides a low degree of certainty based on literature reviews. Furthermore, many others show a very frequent occurrence of unclear or nonexistent knowledge in their profiles. The current welfare state is therefore poor for the majority of farmed aquatic species; yet, there is considerable potential for improvement. However, many species are very unlikely to achieve good welfare, even under high-standard conditions. Importantly, large knowledge gaps remain for an accurate assessment of the welfare of several farmed species.

A traits-based approach to assess aquaculture’s contributions to food, climate change, and biodiversity goals

Aquaculture has the potential to support a sustainable and equitable food system in line with the United Nations Sustainable Development Goals (SDG) on food security, climate change, and biodiversity (FCB). Biological diversity amongst aquaculture organisms can drive diverse contributions to such goals. Existing studies have assessed the performance of a limited number of taxa in the general context of improving aquaculture production, but few explicitly consider the biological attributes of farmed aquatic taxa at the FCB nexus. Through a systematic literature review, we identify key traits associated with FCB and evaluate the potential of aquaculture to contribute to FCB goals using a fuzzy logic model. The majority of identified traits are associated with food security, and two-thirds of traits linked with food security are also associated with climate change or biodiversity, revealing potential co-benefits of optimizing a single trait. Correlations between FCB indices further suggest that challenges and opportunities in aquaculture are intertwined across FCB goals, but low mean FCB scores suggest that the focus of aquaculture research and development on food production is insufficient to address food security, much less climate or biodiversity issues. As expected, production-maximizing traits (absolute fecundity, the von Bertalanffy growth function coefficient K, macronutrient density, maximum size, and trophic level as a proxy for feed efficiency) highly influence a species’ FCB potential, but so do species preferences for environmental conditions (tolerance to phosphates, nitrates, and pH levels, as well as latitudinal and geographic ranges). Many highly farmed species that are typically associated with food security, especially finfish, score poorly for food, climate, and biodiversity potential. Algae and mollusc species tend to perform well across FCB indices, revealing the importance of non-fish species in achieving FCB goals and potential synergies in integrated multi-trophic aquaculture systems. Overall, this study provides decision-makers with a biologically informed assessment of desirable aquaculture traits and species while illuminating possible strategies to increase support for FCB goals. Our findings can be used as a foundation for studying the socio-economic opportunities and barriers for aquaculture transitions to develop equitable pathways toward FCB-positive aquaculture across nuanced regional contexts.

A Pretty Kettle of Fish: A Review on the Current Challenges in Mediterranean Teleost Reproduction.

The Mediterranean region is facing several environmental changes and pollution issues. Teleosts are particularly sensitive to these challenges due to their intricate reproductive biology and reliance on specific environmental cues for successful reproduction. Wild populations struggle with the triad of climate change, environmental contamination, and overfishing, which can deeply affect reproductive success and population dynamics. In farmed species, abiotic factors affecting reproduction are easier to control, whereas finding alternatives to conventional diets for farmed teleosts is crucial for enhancing broodstock health, reproductive success, and the sustainability of the aquaculture sector. Addressing these challenges involves ongoing research into formulating specialized diets, optimizing feeding strategies, and developing alternative and sustainable feed ingredients. To achieve a deeper comprehension of these challenges, studies employing model species have emerged as pivotal tools. These models offer advantages in understanding reproductive mechanisms due to their well-defined physiology, genetic tractability, and ease of manipulation. Yet, while providing invaluable insights, their applicability to diverse species remains constrained by inherent variations across taxa and oversimplification of complex environmental interactions, thus limiting the extrapolation of the scientific findings. Bridging these gaps necessitates multidisciplinary approaches, emphasizing conservation efforts for wild species and tailored nutritional strategies for aquaculture, thereby fostering sustainable teleost reproduction in the Mediterranean.

Nutritional Value of Eggs in Human Diet

Poultry is one of the most widespread food industries worldwide. Chicken is the most farmed species, with over 90 million tons of chicken meat produced per year [19]. Eggs have been a human food since ancient times. They are one of nature’s nearly perfect protein foods and have other high-quality nutrients. Eggs are readily digested and can provide a significant portion of the nutrients required daily for growth and maintenance of body tissues. They are utilized in many ways both in the food industry and the home. The term “eggs”, without a prefix, generally relates to chicken eggs and is so considered in this study [23]. Chicken eggs are one of the best sources of high-quality protein along with important vitamins and minerals. In both developed and developing countries an increased egg production and consumption could significantly improve nutritional needs of adults and children. Eggs are also an economical source of nutrients for a healthy diet and life, especially important for the mental development of growing children [19]. The purpose of this study is to describe the nutritional benefits of eggs in the human diet. Hence, in this study methodology/approach; the scientific literature was searched using Medline and key words relevant to eggs, egg nutrients and it is nutritional roles.

Genetic structure of Macrobrachium nipponense, an important farmed freshwater shrimp in China, in the Three Gorges Reservoir

Macrobrachium nipponense is a major farmed species freshwater shrimp in China and its genetic diversity is of high value in aquaculture. The construction of the Three Gorges Project has slowed down the water velocity in the Three Gorges Reservoir (TGR) and made the water more clear, which is more favourable for the survival and reproduction of M. nipponense. However, there are lack of studies on the genetic diversity of M. nipponense populations in the TGR. In this study, mitochondrial COI gene sequences were used as molecular marker to analyze the genetic diversity, genetic differentiation and historical demography of eight M. nipponense populations in the TGR. The results showed that the M. nipponense populations in TGR have high genetic diversity. There was some genetic differentiation between the four populations in lower reaches of the TGR and four populations in the upper reaches of the TGR. We also found that there was a significant correlation between genetic distance and geographical distance among the M. nipponense populations in the TGR. The M. nipponense population in the TGR has experienced population reduction in the recent year, which might be related to the ice age movement in the Little Ice Age and human activities. This study provides a theoretical basis for the rational development and protection of M. nipponense resources in the TGR.

The Recent Advances to Increase Nutrient Utilization of Dietary Plant Proteins by Enzyme Supplementation and Fermentation in Rainbow Trout (Oncorhynchus mykiss): A Review

Aquaculture is the fastest growing animal production sector globally. However, its sustainability heavily relies on the development of nutritionally balanced cost-effective and environmentally friendly aqua feeds for fish and crustacean species that are already being farmed or the candidate species for intensive farming in the future around the world. Therefore, feeds produced for farmed aquatic species should be highly digestible in terms of nitrogen and phosphorous contents in order to avoid excessive release of these nutrients into the water column through solid and soluble discharge. Excessive nitrogen and phosphorous in the water are the main reason of eutrophication occurring causing severe depletion of oxygen and creating hypoxia for many aquatic organisms living inside water column. Strategies like formulating aqua feeds on required DP/DE (Digestible Protein/Digestible non-protein Energy) basis for farmed species and using synthetic enzymes as feed additives in order to make plant phosphorous bioavailable for fish are being utilized by the commercial aqua feed producers around the world. Fermenting plant protein ingredients with microorganisms and using prebiotics and probiotics as feed additives are also considered a viable option to reduce the nutrient load of aquafarms since these have been shown to increase the digestibility of feed ingredients via increased gut health maintaining the optimal composition and environmental conditions for gut microbiome. In this regard, this review is intended to emphasize the importance of the sustainability efforts of aquaculture production from the perspectives of environmentally friendly aqua feed formulations and improvements based on the recent knowledge gathered for the effects of dietary external enzyme supplementation and fermentation of plant ingredients on growth and wellbeing of rainbow trout (Oncorhynchus mykiss) throughout the world.

Exposure of farmed fish to petroleum hydrocarbon pollution and the recovery process: A simulation experiment with tiger puffer Takifugu rubripes

Petroleum hydrocarbon (PH) pollution threatens both wild and farmed marine fish. How this pollution affects the nutrient metabolism in fish and whether this effect can be recovered have not been well-known. The present study aimed to evaluate these effects with a feeding trial on tiger puffer, an important farmed species in Asia. In a 6-week feeding trial conducted in indoor flow-through water, fish were fed a control diet (C) or diets supplemented with diesel oil (0.02 % and 0.2 % of dry matter, named LD and HD, respectively). Following this feeding trial was a 4-week recovery period, during which all fish were fed a same normal commercial feed. At the end of the 6-week feeding trial, dietary PH significantly decreased the fish growth and lipid content. The PH significantly accumulated in fish tissues, in particular the liver, and caused damages in all tissues examined in terms of histology, anti-oxidation status, and serum biochemical changes. Dietary PH also changed the volatile flavor compound profile in the muscle. The hepatic transcriptome assay showed that the HD diet tended to inhibit the DNA replication, cell cycle and lipid synthesis, but to stimulate the transcription of genes related to liver protection/repair and lipid catabolism. The 4-week recovery period to some extent mitigated the damage caused by PH. After the recovery period, the inter-group differences in some parameters disappeared. However, the differences in lipid content, anti-oxidase activity, liver PH concentration, and histological structure still existed. In addition, differences in cellular chemical homeostasis and cytokine-cytokine receptor interaction at the transcriptional level can still be observed, indicated by the hepatic transcriptome assay. In conclusion, 6 weeks of dietary PH exposure significantly impaired the growth performance and health status of farmed tiger puffer, and a short-term recovery period (4 weeks) was not sufficient to completely mitigate this impairment.

Evaluation of the Reproductive Performance of Females of Anguilla anguilla Characterized by Different Levels of Silvering

The European eel, Anguilla anguilla (Linnaeus, 1758), is a species of high conservation and commercial value. Also, with a high aquacultural value, it was one of the most farmed species in Europe before its decline. Conservation measures for this species are currently being implemented, some of which are the release of adults to allow them to migrate to spawning grounds and artificial reproduction to minimise the impact of overfishing. Much progress has been made regarding the closing of the life cycle, but several problems remain to be solved, such as the weaning and growth of larvae. In this regard, the study of local populations and the identification of the best spawners could be a good way forward as it would help to identify spawners with high reproductive potential and good offspring quality. In this study, we compared the reproductive performance of female eels from migratory areas of the Northern Adriatic Sea at different maturation stages (10 pre-migrant stage; 10 migrant stage), treating both groups with the same hormonal protocol (weekly carp pituitary extract, injection of 17α,20β-Dihydroxy-4-pregnen-3-one at complete oocyte maturation). The research showed that eels at the beginning of metamorphosis (SI III), i.e., eels not yet ready to undertake migration, achieve reproductive performance equal to that of eels ready for migration (SI IV). Their performance was on par in both qualitative and quantitative terms. The optimal results in hatching (with values of 65.8 ± 3.2% for pre-migrant and 68.2 ± 4.1% for migrant) and survival rates (with value of 25.7 ± 5.4% pre-migrants; 27.2 ± 3.7% migrants), as well as the results about the time to reach full gonadal maturation, may have positive implications when considering release and restocking measures.

What Are the Prospects of Sustainable Aquaculture in the Niger Delta, Nigeria?

Globally, the wild capture fishery is declining, and aquaculture is expanding to help fill the gap, especially in Asia and developing countries. However, the sustainability of the aquaculture sector is raising questions, and answering those questions requires the adoption of new technologies and better management practices. Nowhere is this seen more clearly than in Nigeria where aquaculture generally means catfish, the most farmed species of which is clarias garipinus because it is a native species, and it plays an important role in the average Nigerian diet. However, small-scale catfish aquaculture businesses are affected by various challenges that threaten the sustainability of the sector. Prominent among these challenges are: poor management skills; lack of good quality fish seed supply; high cost of fish feed; inconsistency in government policy and limited regulations; lack of consideration about the impacts of aquaculture practice on the environment causing water pollution and environmental degradation, and insecurity of investment against natural disasters such as floods. This research investigated these challenges in eight sites in two states (Delta and Bayelsa) in the Niger Delta region of Nigeria. Data were gathered from a survey questionnaire, key informant interviews, personal observations, and published literature. Key findings showed that the sustainable development of the small-scale catfish farming industry in Delta and Bayelsa states is vulnerable to several threats that prevent it from fulfilling its undoubted potential to grow into a much larger sector, which could significantly reduce Nigeria’s reliance on fish imports, as well as relieve pressure on the overfished marine catch sector. Nevertheless, despite the threats, most catfish farmers are committed to their work and deserve the support of the government to enable them to succeed.

Untargeted lipidomics for evaluating fish authenticity: the case of wild-caught and farmed species of Sparus aurata

Aim: This study aims to develop sensitive and reliable analytical technologies to enable the distinction between wild-caught and farmed fish through appropriate molecular markers to protect consumers from fraudulent fish labelling. Gilthead sea bream, Sparus aurata L. (S. aurata L.), is a very common fish used as foodstuff worldwide and globally produced in aquaculture in the Mediterranean basin. Wild-caught and farmed species are very different in feed and lifestyle and the quality and safety of these products strongly depend on fish growth, processing history, and storage conditions. Methods: Hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray ionization (ESI) and Fourier-transform mass spectrometry (FTMS; HILIC-ESI-FTMS) was employed to discriminate the phospholipidome profiles of fillets extracts of wild-caught from farmed gilthead sea breams. Results: The untargeted approach led to the annotation of a total of 216 phospholipids (PLs), namely 65 phosphatidylethanolamines (PEs), 27 lyso-PEs (LPEs), 61 phosphatidylcholines (PCs), 34 lyso-PCs (LPCs), and 29 sphingomyelins (SMs). Untargeted lipidomics data were investigated by principal component analysis (PCA) and K-means clustering. Lyso-PLs (LPLs) of PEs and PCs including ether-linked side chains were found as discriminating markers between the two types of fish samples. The PLs that were most responsible for distinguishing between the lipid extracts of farmed and wild S. aurata fillets were successfully characterized by tandem mass spectrometry (MS/MS). The analysis revealed that wild fillet lipid extracts contained some PE exhibiting ether bonds (PE P-), viz. 16:0, 18:0, 18:1, and 18:2 and polyunsaturated fatty acyl chains (i.e., 22:6 and 22:5). In farmed species, the estimated abundance ratios of fatty acyl chains 20:4/18:2 and 22:6/20:5 were 0.9 and 0.05, respectively. However, in wild-caught fish, these ratios were found to be two-fold higher and four-fold higher, respectively. Conclusions: This work demonstrates that the combination of HILIC-ESI-FTMS and chemometrics can serve as a valuable tool for evaluating fish authenticity and assessing quality concerns by monitoring specific lipid ratios.

Diet of snapper (Chrysophrys auratus) in green‐lipped mussel farms and adjacent soft‐sediment habitats

AbstractWild fish utilise aquaculture habitats for shelter and/or food resources. It is often assumed that fish respond to feed input, the abundance of the farmed species or the associated assemblage of biofouling which naturally colonises the structural habitats. However, few studies have directly analysed the composition of the diet of fish within aquaculture habitats, and of these most have focused on fed finfish aquaculture. Snapper are commonly present as adults within coastal mussel farms and tend to become a resident species of these farms. Therefore, they are a suitable case study species for exploring differences in diet between natural and aquaculture habitats. This study investigated the gut contents of snapper in soft‐sediment habitats within and outside of New Zealand green‐lipped mussel farms. Visual gut analysis and DNA metabarcoding methods were used to provide complementary analyses on the composition of gut contents between the mussel farm and natural (i.e., control) sites. Snapper within mussel farms were consistently found to have consumed different prey groups compared to the control snapper. Prey groups identified from mussel farm snapper gut contents could be directly linked to species commonly present in the farms, that is cultured green‐lipped mussels, blue mussels and barnacle biofouling. There was good alignment between the visual gut and genetic analyses for the key species identified. Overall, the results show that the highly abundant prey groups consumed by snapper in mussel farm habitats are likely to be beneficial to the snapper population, reducing foraging effort and potentially supplying more nutritious prey. These findings provide evidence towards the supporting services of mussel farm habitats through the provision of food resources.

Performing surgery in goats. Part 1: preparation and regional anaesthesia

Background: The population of goats within the UK continues to rise and, according to latest Defra figures, now totals approximately 111,000 animals. With this comes the increasing likelihood that general practitioners will have something to do with these fascinating and characterful farmed species. The UK goat sector is one of the most diverse within the agricultural setting, being comprised of three main commercial wings: dairy, meat and fibre, and the remainder spread across pedigree and/or show stock, public attraction stock, small holder stock and those kept exclusively as pets. All these different settings have multiple and intertwining crossovers, which means the manner in which our caprine patients are kept, handled, managed and cared for can be equally disparate. The general practitioner must be aware of the circumstances and surroundings in which the animals are kept. Additionally, goats are generally of a gregarious and hierarchical nature, which can lead them into harm's way or mischief, and may necessitate various veterinary interventions.Aim of the article: This article, the first in a two part series, aims to equip general veterinary practitioners with the necessary knowledge and top tips for performing regional anaesthetic techniques in this species, while also highlighting how to stay on the right side of the law when it comes to available pharmaceuticals.

Feeding gilthead sea bream with increasing dietary bacterial single cell protein level: Implication on growth, plasma biochemistry, gut histology, and gut microbiota

Bacterial single cell protein (SCP) is considered a promising circular protein ingredient for aquafeed, due to the high protein content, and for the possibilities to grow them on different substrates such as organic waste thus leading to low environmental footprint and affordable production costs. Their use as raw material has been assessed in several farmed species, however, research on Mediterranean ones is still scarce. Hence, a study was undertaken to evaluate growth, plasma biochemistry, gut histology and gut microbiota (GM) response of gilthead sea bream (Sparus aurata) fed diets with increasing levels of bacterial SCP in comparison to a control without SCP. Three isonitrogenous and isolipidic extruded diets (44% protein; 19% lipid) were formulated with different bacterial SCP (derived from Corinebacterium glutamicum) level (10% SCP, SPC10; 15% SCP, SCP15; 20% SCP, SCP20) to replace vegetable protein ingredients (total replacement of soy protein concentrate and partial replacement of corn gluten), while a control diet (CTRL) was formulated without SCP. Fish groups of 45 individuals (initial weight: 75 g) were fed to visual satiation over 108 days. At the end of the trial there were no significant differences on growth, feed intake, feed conversion rate, protein efficiency ratio and protein apparent digestibility. Most of plasma parameters were found to be equal for all treatments, except for those related to nucleic acids molecules degradation such as phosphorus and urea which were higher in SCP10 and SCP20 compared to CTRL, respectively. No morphological alterations were found in the intestines of any fish analysed. Different responses of the overall GM structure in relation to the bacterial SCP inclusion level were detected. Specifically, SCP exerted a positive effect on GM internal diversity which increased at increasing dietary SCP inclusion level. In addition, SCP inclusion lead to increase in the abundance of Bacillus spp., taxa which can potentially support nutrition, immune system, and disease resistance. In conclusion, it seems feasible to include up to 20% of SCP dietary level for gilthead sea bream without compromising growth, feed efficiency and health parameters.

The Quail Game Farming Sector in Spain.

Quail (Coturnix genus) game farms were characterised in Spain using variables related to their age, geographical distribution, farmed species, structure, size, and commercialisation, using a survey conducted on 21 farms in 2018. It was found that 38.1% of the sample represented complete-cycle farms, and 61.9%, which have no breeding flocks, undertook only the finishing phase of quail raising. The average size of the breeding flock, with regard to complete-cycle farms, was 1096 males and 3735 females, with a female/male ratio of 3.6, and 75% of these farms carried out self-replacement of breeding quails. The most farmed species was European quail (Coturnix coturnix), followed by Japanese quail (Coturnix japonica), and hybrids of both species. In addition to quail, all farms produced other gamebird species such as pheasant (Phasianus colchicus) and red-legged partridge (Alectoris rufa). The rearing phase, which began when the chicks were one-day-old, lasted 35.3 days on average (range: 25-49 days), with an average stocking density of 47.2 birds/m2 in the brooder house. The finishing phase, which was carried out in flying pens at a stocking density of 9.5 birds/m2, ended when the quails' average age was 60.5 days. All farms sold quails for release in hunting reserves (EUR 1.54 per bird) and for dog training (EUR 1.65 per bird) for almost 10 months of the year; only 62% sold quails for shooting after being thrown with an adapted clay-pigeon shooting machine (EUR 1.49 per bird). Transporting quails to their destination (95.2% of the farms) and releasing the birds in the client's hunting preserve (52.4% of the farms) were services offered by the farms, among others. The main advertising and promotional strategies undertaken by the quail game farms to gain a share of the market included maintaining a business website (85.7% of the farms) and attending game and agricultural fairs (47.6% of the farms). In conclusion, this alternative poultry sector has been consolidated in Spain, five decades since the establishment of the first game farms, and it satisfies a relevant part of the demand for quail hunting.

Transcriptome analysis identifies LGP2 as an MDA5-mediated signaling activator following spring viremia of carp virus infection in common carp (Cyprinus carpio L.).

The common carp (Cyprinus carpio L.) is an important farmed species worldwide. Mucosal-associated lymphoid tissues play an essential role in the fight against pathogen infection. Spring viremia of carp virus (SVCV) poses a serious threat to the common carp aquaculture industry. Understanding the molecular mechanisms driving mucosal immune responses to SVCV infection is critical. In this study, the mucosal tissues (gills, foregut and hindgut) were collected from normal and infected fishes for transcriptome analysis. A total of 932,378,600 clean reads were obtained, of which approximately 80% were successfully mapped to the common carp genome. 577, 1,054 and 1,014 differential expressed genes (DEGs) were identified in the gills, foregut and hindgut, respectively. A quantitative polymerase chain reaction assay indicated that the DEGs expression in the foregut following SVCV infection was consistent with the transcriptome results. Among them, two key genes of the retinoic acid-inducible gene I (RIG-I)-like receptor family, melanoma-differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2) (i.e., CcMDA5 and CcLGP2), underwent further analysis. Overexpression of CcMDA5 or CcLGP2 increased phosphorylation of TANK-binding kinase 1 and interferon regulatory factor 3 and the expression of interferon-1 (ifn-1), myxovirus resistance (mx), viperin and interferon-stimulated gene 15 (isg15), and inhibited SVCV replication in epithelioma papulosum cyprini cells. Furthermore, CcLGP2 significantly upregulated the CcMDA5-induced ifn-1 mRNA expression and the activation of the ifn-1 promoter. Finally, confocal microscopy and coimmunoprecipitation experiments revealed that CcLGP2 colocalizes and interacts with CcMDA5 via the C-terminal regulatory domain. This study provides essential gene resources for understanding the fish immune response to SVCV infection and sheds light on the potential role of fish LGP2 in the MDA5 regulation.

A cross-sectional study in Mediterranean European countries to support stakeholders in addressing future market demands: Consumption of farmed fish products

Aquaculture is now a viable alternative to help depleted wild fish stocks and encourage the production of alternative animal protein sources. However, studies have shown that farmed fish has a less positive image in consumers than wild fish. The present study investigates the aspects that most influence the consumption choices of some of the most farmed species in the Mediterranean, sea bass and sea bream. The objective is to analyse the habits and preferences of consumers of these products in Mediterranean countries to identify homogeneous and transversal behaviours in the four countries under analysis in order to recognise common marketing actions and levers. To achieve it, a direct survey was conducted on a representative sample of 6117 consumers from France, Spain, Greece and Italy. The cluster analysis carried out for the four countries revealed 11 well-defined consumer profiles. They showed that different socio-economic characteristics, purchasing habits and product attributes explain a significant part of consumption choices and offer key information for exploring food consumer attitudes. In addition, the role of labelling in consumer behaviour is important to understand which aspects consumers pay more attention to when making their choices, representing a discriminating factor in segmenting respondents' profiles. Understanding these preferences, and the importance of certain information, can be useful to intercept and respond to market demands and to improve consumer confidence in farmed fish products.

A chromosome-level genome of Portunus trituberculatus provides insights into its evolution, salinity adaptation and sex determination.

Portunus trituberculatus (Crustacea: Decapoda: Brachyura), commonly known as the swimming crab, is of major ecological importance, as well as being important to the fisheries industry. P. trituberculatus is also an important farmed species in China due to its rapid growth rate and high economic value. Here, we report the genome sequence of the swimming crab, which was assembled at the chromosome scale, covering ~1.2Gb, with 79.99% of the scaffold sequences assembled into 53 chromosomes. The contig and scaffold N50values were 108.7kb and 15.6Mb, respectively, with 19,981 protein-coding genes. Based on comparative genomic analyses of crabs and shrimps, the C2H2 zinc finger protein family was found to be the only gene family expanded in crab genomes, suggesting it was closely related to the evolution of crabs. The combination of transcriptome and bulked segregant analysis provided insights into the genetic basis of salinity adaptation and rapid growth in P. trituberculatus. In addition, the specific region of the Y chromosome was located for the first time in the genome of P. trituberculatus, and three genes were preliminarily identified as candidate genes for sex determination in this region. Decoding the swimming crab genome not only provides a valuable genomic resource for further biological and evolutionary studies, but is also useful for molecular breeding of swimming crabs.

Black soldier fly larval meal with exogenous protease in diets for rainbow trout (Oncorhynchus mykiss) production meeting consumer quality

A protein gap exists within the supply of fish feed ingredients due to intensifying global aquaculture production and demands. This is distinctly acute in salmonid farming where protein requirements are higher to other aquatic farmed species. In pursuit of a viable alternative, an eight-week feeding trial was conducted to evaluate the feasibility of including reared black soldier fly (BSF, Hermetia illucens ) larvae into rainbow trout ( Oncorhynchus mykiss ) diets. Five diets were formulated: a fish meal-based basal diet (CTRL), two diets of BSF incorporation at 15 and 30% (BSF15; BSF30), and two diets at the same incorporation level with the addition of a supplementary protease enzyme (BSF15P; BSF30P) assigned to test potential dietary enhancement. No significant growth performance between the dietary treatments was observed. The fish condition factor in BSF30 was higher than BSF30P ( P =0.025). Fillets showed increased muscle yellowness as dietary BSF increased ( P =0.004). Trout fed BSF displayed significantly lower lipid peroxidation post-harvest ( P < 0.001), with the level of malondialdehyde decreasing with increased dietary BSF, regardless of protease inclusion. BSF meal elevated the saturated fatty acid content of fillets significantly ( P < 0.001) while monounsaturated fatty acids decreased ( P < 0.001). BSF protease treatments elevated the total concentration of protein in the trout body content, reflecting potentially improved protein utilisation efficiency. BSF diet with protease inclusion is a feasible protein and energy concentrate to replace fish meal in rainbow trout diets up to 30%, without negative effects on the growth, proximate composition, fatty acid profile, lipid peroxidation and fillet colour stability of rainbow trout. • Inclusion of black solider fly larvae meal maintains trout growth performance. • Increase in fillet lauric fatty acid content was found in insect meal fed trout. • Use of protease elevated protein content in trout fed with black solider fly meal. • Black soldier fly meal decreased fillet lipid peroxidation. • An increase of fillet yellowness was found in solider fly meal fed trout.

Metabolomics in salmonid aquaculture research: Applications and future perspectives

AbstractSalmonids are the third major farmed finfish species after carps and tilapines, and thus contribute to global food fish production. However, as the aquaculture industry continues to grow, several challenges have emerged. Left unchecked, current problems will hinder aquaculture development. Metabolomics is one of the powerful biotechnological tools that will contribute to solving some of the pressing problems. This review aims to summarise findings and identify gaps from studies that used metabolomics in farmed salmon research. We extracted methodological information for comparison, highlighted analytical platform usages and identified most studied salmonids and sample types. We reviewed key articles to highlight the latest research themes. From the identified research gaps, future perspectives regarding potential use of metabolomics to solve issues in ecotoxicology, thermotolerance, nutrition, post‐harvest quality, health and disease, and husbandry practices are provided. The survey also highlighted improvements in execution of metabolomics protocols in aquaculture.

Seaweeds – a potential source of food, feed and fertiliser

Many communities in the world consume naturally growing and cultivated/ farmed seaweeds as food. Currently, commercial cultivation/farming produces more than 96% of seaweeds in the world and only around 3-4% is obtained from wild harvest (noncultivated). Naturally occurring and cultivated seaweeds are categorized into green, brown and red seaweeds, based on their pigmentation. More than 200 species of seaweeds are of commercial value, but only around 10 species of seaweeds are popularly cultivated. China, Indonesia, the Republic of Korea and the Philippines are the leading producers of cultured/ farmed species (viz. Eucheuma, Japanese kelp, Gracilaria, Unndaria pinnatifid); and Chile, China and Norway for wild species (mainly brown and red) and Chilean kelp. Seaweeds are rich in dietary fiber (polysaccharides), essential amino acids, major and micronutrients (minerals), vitamins etc. It has been reported that some species are a good source of plant growth regulators. Mainly, the people in China, Japan and Korea relish the soups, stews, flakes, coatings, snacks, etc., made from seaweeds. The use of seaweeds as human food in India is not very common. The second major use of seaweeds after food is the extraction of three important hydrocolloids (Agar, Alginate and Carrageenan). These are used as food additives and in many other industrial applications. A small portion of seaweed is used as an ingredient as livestock feed and fish feed. Seaweed meal and liquid extract of seaweed have been tried in conjunction with inorganic fertilizers with beneficial effects on crop yield, quality produce and soil health. Seaweed is an important marine resource and the coastline in India can be utilized to commercially cultivate seaweed species beneficial for human health and plants. Research is required in developing functional foods, health foods and nutraceuticals from seaweeds to improve the health and nutritional status of the human population. This paper briefly describes the status of production and utilization of seaweeds in different parts of the world.