Sustainable Aquaculture Production Research Articles

Perikphyton Growth on Two Different Bamboo Substrate Models for Its Use in Aquaculture

Periphyton-based fish farming practices are considered low-cost technologies as they help in sustainable aquaculture production. The present study was designed to determine the efficiency of two different substrate models (viz. roof hut model and prism model) made from the bamboo sticks. The small-sized substrate models were constructed for invitro studies. The growth of periphyton was investigated on the 30th day of the experimental setup. This is the first time experimenting with bamboo substrate models. From the result it was found that the biomass of periphyton in terms of dry weight 0.03±0.01 g/cm2 was observed on both substrate models. There is no biomass difference and taxonomic difference between these two models. It may be due to the material used for the construction of the model being the same i.e. bamboo sticks and cotton thread. The taxonomic identification of the periphyton community showed the different genera of class Chlorophyceae and Bacillariophyceae. These models are efficient for periphyton growth and they also increase the productivity of periphyton due to increased surface area of substrate models. These models can be used for low-cost aquaculture.

Tissue Lipid Profiles of Rainbow Trout, Oncorhynchus mykiss, Cultivated under Environmental Variables on a Diet Supplemented with Dihydroquercetin and Arabinogalactan.

Reared rainbow trout are vulnerable to environmental stressors, in particular seasonal water warming, which affects fish welfare and growth and induces a temperature response, which involves modifications in tissue lipid profiles. Dietary supplements of plant origin, including the studied mix of a flavonoid, dihydroquercetin and a polysaccharide, arabinogalactan (25 and 50 mg per 1 kg of feed, respectively), extracted from larch wood waste, were shown to facilitate stress tolerance in fish and also to be beneficial for the safety of natural ecosystems and the sustainability of aquaculture production. This four-month feeding trial aimed to determine the effects of the supplement on liver and muscle lipid accumulation and the composition in rainbow trout reared under environmental variables. During periods of environmental optimum for trout, a consistent increase in energy lipid stores, particularly triacylglycerols (2.18 vs. 1.49-fold over a growing season), and an overall increase in lipid saturation due to lower levels of PUFAs, such as eicosapentaenoic (20:5n-3), docosahexaenoic (22:6n-3) and arachidonic (20:4n-6) acids, were observed in both control and supplement-fed fish, respectively. However, in fish stressed by an increase in ambient temperature, dietary supplementation with dihydroquercetin and arabinogalactan reduced mortality (3.65 in control vs. 2.88% in supplement-fed fish, p < 0.05) and alleviated the high-temperature-induced inhibition of lipid accumulation. It also stabilised the membrane phospholipid ratio and moderated the fatty acid composition of fish muscle and liver, resulting in higher levels of n-3 PUFAs and their precursors. Thus, the natural compounds tested are beneficial in accelerating fish tolerance to environmental stressors, reducing mortality and thermal response, and moderately improving fillet quality attributes by increasing the protein/lipid ratio and the abundance of fatty acids essential for human nutrition.

The Role of Environmental Communication in Advancing Sustainability in Fisheries and Aquaculture: A Case Study of Latvia

Latvia has abundant water resources, but the aquaculture sector has been slow to adopt technological advances and innovations. To address this gap, the Latvian Aquaculture Development Plan for 2021–2027 aims to improve the competitiveness and sustainability of the sector. An essential component of this effort is the establishment of effective communication channels that bridge the knowledge gap between the general public, industry professionals and researchers. To promote consumer interest in sustainable aquaculture products, an environmental communication framework to assess their sustainability was used. This assessment utilised a multi-criteria analysis technique complemented by an online survey to formulate an effective communication strategy. According to the multi-criteria analysis, canned fish emerges as the most sustainable product, while fish oil, fish meal and spirulina show promise. The online survey identifies the most appropriate communication channels: social media, audio and video. To facilitate engagement and information sharing, we advocate for the practice of communication, which can effectively facilitate the sustainable use of biological resources and serve as a channel for knowledge sharing.

Assessing 30-Year Land Use and Land Cover Change and the Driving Forces in Qianjiang, China, Using Multitemporal Remote Sensing Images

Assessing Land Use and Land Cover Change (LULCC) related with aquaculture areas is vital for evaluating the impacts of aquaculture ponds on the environment and developing a sustainable aquaculture production system. Most studies analyze changes in aquaculture land in coastal areas, and little research focuses on the inland area, where the conversions between agriculture and aquaculture land is primarily driven by socioeconomic factors. This study assessed LULCC related to aquaculture areas in Qianjiang City, China, from 1990 to 2022, using multitemporal Landsat images and a combination of decision tree classifier and visual interpretation. The LULCC was analyzed by the transition matrix. Results showed that the main LULC type was farmland, which accounted for more than 70% of the study area from 1990 to 2022. The built-up and aquaculture land showed an increasing trend year by year. In contrast, there was a gradual decline in forest/grass land from 1990 to 2016, and then its area increased slightly from 2016 to 2022 due to the policy of returning farmland to forest. Water areas were mainly composed of rivers and ponds, with subtle changes during the study period. The main driving forces of LULCC in Qianjiang City were economic and policy factors, with rapid GDP growth and government policies being the dominant factors.

Recent Developments in Aquaculture and Future Prospects: A Comprehensive Review

In the pursuit of promoting sustainable aquaculture production, numerous cutting-edge technologies have emerged in recent years. The utilization of effective microbes (EM) in managing water quality, the implementation of biofloc technology, aquamimicry, the inclusion of Black Soldier Fly (BSF) as an additional protein source, the use of triploidy and polyploidy, vaccines, probiotics, and prebiotics, the integration of Internet of Things (IoT) for monitoring water quality in the farm operation, the practice of monosex culture, and the application of neo-female techniques are all being employed in aquaculture operations. The advancements in these cutting-edge technologies have been focused on promoting sustainable aquaculture production, mitigating the risk of disease outbreaks, enhancing crop yields, and contributing to eco-friendly environmental initiatives. This review paper highlights the cutting-edge technologies that have emerged in the field of aquaculture in recent years, up until the present time, with a focus on advancements in fish nutrition. The advancements in aquaculture technology have been instrumental in promoting the achievement of sustainable development goals, particularly SDG-1 (no poverty) and SDG-2 (zero hunger). These goals are aimed at reducing poverty and eliminating hunger by utilizing the enhanced aquaculture production facilitated by the latest technological innovations. In the arena of aquaculture, this review paper has the potential to nourish the minds of aquaculturists and aquafarmers with a bountiful feast of knowledge. It unveils the latest technologies and developments in the realm of aquaculture, serving as a nutritious resource that can enhance the operation of cultures and promote a fruitful increase in production in the not-so-distant future.

Chitosan neem nanocapsule enhances immunity and disease resistance in nile tilapia (Oreochromis niloticus)

Finding eco-friendly alternatives for antibiotics in treating bacterial diseases affecting the aquaculture sector is essential. Herbal plants are promising alternatives, especially when combined with nanomaterials. Neem (Azadirachta indica) leaves extract was synthesized using a chitosan nanocapsule. Chitosan neem nanocapsule (CNNC) was tested in-vitro and in-vivo against the Aeromonas sobria (A. sobria) challenge in Nile tilapia. A preliminary experiment with 120 Nile tilapia was conducted to determine the therapeutic dose of CNNC, which was established to be 1 mg/L. A treatment study was applied for seven days using 200 fish categorized into four groups (10 fish/replicate: 50 fish/group). The first (control) and second (CNNC) groups were treated with 0 and 1 mg/L CNNC in water without being challenged. The third (A. sobria) and fourth (CNNC + A. sobria) groups were treated with 0 and 1 mg/L CNNC, respectively, and challenged with A. sobria (1 × 107 CFU/mL). Interestingly, CNNC had an in-vitro antibacterial activity against A. sobria; the minimum inhibitory concentration and minimum bactericidal concentration of CNNC against A. sobria were 6.25 and 12.5 mg/mL, respectively. A. sobria challenge caused behavioral alterations, skin hemorrhage, fin rot, and reduced survivability (60%). The infected fish suffered a noticeable elevation in the malondialdehyde level and hepato-renal function markers (aspartate aminotransferase, alanine aminotransferase, and creatinine). Moreover, a clear depletion in the level of the antioxidant and immune indicators (catalase, reduced glutathione, lysozymes, nitric oxide, and complement 3) was obvious in the A. sobria group. Treatment of the A. sobria-challenged fish with 1 mg/L CNNC recovered these parameters and enhanced fish survivability. Overall, CNNC can be used as a new versatile tool at 1 mg/L as a water treatment for combating the A. sobria challenge for sustainable aquaculture production.

Nutritional Fish Diseases in Aquaculture: A Human Health Hazard or Mythical Theory: An Overview

To consume or not to consume farmed fish diagnosed with nutritional disorders within an aquaculture culture system is a question that resonates with fisheries and aquaculture experts worldwide. Proper fish health management in aquaculture should be a critical area of concern for all fish farmers. It has become a fundamental requirement for achieving sustainable aquaculture production. However, many fish farmers, particularly in developing countries lack knowledge about nutritional fish diseases and how to effectively manage them on the farm. Like human health, farmed fish’s health in aquaculture systems should be a daily priority for fish farmers. Nutritional fish diseases are often overlooked by the majority of fish farmers, even at the commercial level. Most Fish farmers may not realize that nutritional disease prevention can be achieved through the use of well-formulated fish feeds that meet all the nutritional requirements for fish growth. Additionally, maintaining good water quality and implementing best management practices are essential to ensure that the fish stock remains healthy in the culture system. Since different fish species have varying nutritional dietary requirements, it is important to formulate the right nutritional diet based on the specific fish species being cultured. Fish feeds should contain the necessary nutrients to ensure opportunistic disease resistance. Furthermore, fish farmers should be familiar with early diagnosis techniques for nutritional fish disease disorders. This ensures that the harvested fish reaching the market does not raise concerns about the quality and safety of farmed fish products. Failure to diagnose nutritional disorders associated with poor feeds and diets can create doubts in the rapidly growing aquaculture industry. Therefore, this review aims to explore the nutritional requirements of farmed fish species, the impact of nutritional deficiencies on human and public health, the causes of nutritional disorders, and viable therapies for managing these diseases in farmed fish. The data for this review article were collected from various secondary sources, including internationally reputable peer-reviewed articles, conference proceedings reports, internet searches, and more. The findings highlight the importance of providing aquaculture farmers with essential information on fish nutrition-related disease control, as nutritional diseases have been found to be detrimental to fish health and public health. Moreover, many farmed fish affected by nutritional disorders have entered the global fish market, raising questions about their impact on human health. Therefore, it is crucial for fish farmers to prioritize early diagnosis of nutritional fish diseases to ensure the safety of farmed fish in the market and maintain consumer confidence in farmed fish globally. The study recommends further research into the potentially lethal effects of different nutritional fish diseases, particularly when consumed in large quantities and to the environment especially when dead fish is discarded in the backwaters of an aquatic ecosystem.

Recent developments in aquaculture – A review

Abstract Towards the sustainable aquaculture production, more recent technologies have been developed in the past few years. The application of effectives microbes (EM) in controlling water quality, the application of biofloc technology, aquamimicry, black soldier fly (BSF) as supplemental protein feed, application of triploidy, polyploidy, vaccines, probiotic and prebiotic, Internet of Things (IoT) in monitoring the water quality in the farm operation, monosex culture and neo-female application also being applied in the aquaculture operation. The developments of these recent technologies were towards achieving the sustainable aquaculture production, prevention of the disease outbreak, help in increasing the yield of crops harvested as well as towards the green environmental developments. This review paper emphasizes the most recent technologies developed in aquaculture in the past few years until these days. The developments of the new technology in aquaculture also in order to support the sustainable development goals (SDGs) proposed by the United Nation focused on SDG1 (no poverty) and SDG2 (zero hunger) from the increase of aquaculture production achieved through the recent developed technology. Ultimately, this review paper can generate new knowledge and information to the aquaculturist and aquafarmers on the new technologies and developments in aquaculture which could help benefit in the cultures operation and increase production in the near future.

Hematological, immuno-antioxidant disruptions, and genes down-regulation induced by Aeromonas veronii challenge in Clarias gariepinus: The ameliorative role of silica nanoparticles.

Aeromonas veronii is a pathogenic bacterium associated with various diseases in aquaculture. However, few studies address the antibacterial activity using nanoparticles (NPs). Hence, the current study is innovative to evaluate the antibacterial efficacy of silica nanoparticles (SiNPs) against A. veronii infection in-vitro with a trial for treatment in-vivo. Primarily, we assessed the in-vitro antibacterial activity against A. veronii. Further, we investigated the hematological profile, immune-antioxidant response, and gene expression of African catfish (Clarias gariepinus) in response to SiNPs exposure and the A. veronii challenge. Fish (N = 120; weight: 90 ± 6.19 g) were distributed into four groups (30 fish/group) for a ten-days-treatment trial. The first (control) and second (SiNPs) groups were treated with 0 mg/L and 20 mg/L SiNPs in water, respectively. The third (A. veronii) and fourth (SiNPs+A. veronii) groups were treated with 0 mg/L and 20 mg/L SiNPs in water, respectively, and infected with A. veronii (1.5×107 CFU/mL). Results demonstrated that SiNPs displayed an in-vitro antibacterial activity against A. veronii with a 21 mm inhibitory zone. A. veronii infection caused a high mortality rate (56.67%) and substantial reductions in hematological indices and immune indicators [nitric oxide (NO) and immunoglobulin M (IgM)]. Additionally, marked decline in the level of antioxidants [superoxide dismutase (SOD), catalase (CAT), and reduced glutathione content (GSH)] as well as down-regulation in the immune-related genes [interleukins (IL-1β and IL-8) and tumor necrosis factor-alpha (TNF-α)] and antioxidant-related genes [SOD1, glutathione peroxidase (GPx), and glutathione-S-transferase (GST)] were the consequences of A. veronii infection. Surprisingly, treatment of A. veronii-infected fish with SiNPs lessened the mortality rate, enhanced the blood picture, modulated the immune-antioxidant parameters, and resulted in gene up-regulation. Overall, this study encompasses the significant role of SiNPs, a new versatile tool for combating hematological, immuno-antioxidant alterations, and gene down-regulation induced by A. veronii infection and sustainable aquaculture production.

Use of marine microorganisms in designing anti-infective strategies for sustainable aquaculture production.

Aquaculture, a noteworthy food production sector, is confronted with disease occurrences. Treatment of aquaculture pathogens with antibiotics is often rendered ineffective due to biofilm formation and the development of resistant strains. Marine ecosystems encompass unusual microorganisms that produce novel bioactive compounds, including agents that could be used as alternatives to antibiotics. Moreover, biomass and/or biomolecules associated with these microorganisms could act as feed supplements to enhance overall health of aquaculture species' and improve water quality parameters. The present review summarizes contents of studies on such marine microorganisms with the potential to be developed as agents for tackling bacterial diseases in the aquaculture segment. Bioactive compounds produced by marine bacteria are known to inhibit biofilm associated infections mediated by their bactericidal properties (produced by Bacillus, Vibrio, Photobacterium and Pseudoalteromonas species), surfactant activity (obtained from different species of Bacillus and Staphylococcus lentus), anti-adhesive activity (derived from Bacillus sp. and Brevibacterium sp.) and quorum sensing inhibition. Several marine fungal isolates capable of producing antibacterial agents have also been effective in inhibiting aquaculture associated pathogens. Another strategy followed by investigators to reduce severity of infections is the use of bacterial, yeast and microalgae biomass as feed supplements, probiotics and immunostimulants. In some cases, marine microalgae have been employed as sustainable alternatives to fish oil and fish meal without compromising on nutritional quality. Their inclusion in aquaculture feed have enhanced growth, favoured better survival of cultured species and improved water quality parameters. Marine microorganisms (by providing effective bioactive compounds and being used as feed supplements) could enable aquaculture practices to be more sustainable in the future.

Comparison of genetic diversity of farmed Oreochromis niloticus and wild unidentified tilapia (Wesafu) using microsatellite markers

Abstract. Ukenye EA, Megbowon I. 2023. Comparison of genetic diversity of farmed Oreochromis niloticus and wild unidentified tilapia (Wesafu) using microsatellite markers. Biodiversitas 24: 2953-2957. Nile tilapia (Oreochromis niloticus Linnaeus, 1758) and unidentified tilapia (Wesafu) are cichlid species of important nutritional and economic value with good aquaculture potential. Assessing and comparing the genetic diversity of these cichlid species will assist in information development for conservation and management strategies to improve their overall productivity and sustainable aquaculture production. Using twenty fish specimens each from farmed O. niloticus and ecotype, Wesafu from the wild respectively, we examined the genetic diversity between these two cichlid species. Eight microsatellite loci were utilized to molecularly characterize and compare these two cichlid species from the wild and farm based on their genetic variation levels. Genetic diversity was investigated from isolated, amplified and resolved DNA of the two cichlid species obtained from the wild and farm. The microsatellite markers analysis revealed that ecotype, Wesafu from the wild exhibited higher genetic diversity than farmed O. niloticus as evidenced by the effective number of alleles (1.756), Shannon information index (0.596), observed and expected heterozygosity values (0.682 and 0.400). All genetic diversity indices were observed to have declined in farmed populations due to inbreeding. However, farmed O. niloticus recorded more polymorphism (87%) than ecotype, Wesafu from the wild (75%). Low genetic differentiation was found between the farmed and wild cichlid species according to the fixation index (-0.628) while Principal Coordinate Analysis (PCoA) demonstrated some level of variation between the two cichlid species. This finding provides more insights into the conservation of the genetic resource and better management of these species to minimize inbreeding in aquaculture. We advise that only wild broodstocks should be used for fish restocking in breeding program for sustainable aquaculture production.

Innovation policy in the Norwegian aquaculture industry: Reshaping aquaculture production innovation networks

While aquaculture production in a number of countries has been highly successful in terms of production growth, there is also a number of instances where the rapid growth has been curtailed due to sustainability challenges. In response, fostering sustainable aquaculture production has become a key policy and research agenda. The point of departure for this paper is the radical technological innovations based sustainable restructuring dynamics of the Norwegian salmon farming industry, which despite becoming one of the most profitable aquaculture industries in the world, has in recent years seen its growth curtailed due to sustainability challenges. To address these challenges and to enable the use of new areas currently inaccessible by the incumbent aquaculture technology, the Norwegian authorities launched in 2015 a new type of innovation policy instrument, known as development licences. Based on a mapping of the aquaculture production technology development projects as well as in-depth interviews, this paper elucidates how the targeted innovation policy instrument has instigated the sustainable restructuring process of the Norwegian aquaculture industry. Our findings indicate that in the short term, the innovation policy appears to have succeeded in the reconfiguration, and more precisely, the 'renewal' process of the aquaculture production technology innovation networks (ecosystems) thanks to the entry of the new capable actors into the segment. However, we emphasise that the overall success of the innovation policy instrument will ultimately hinge upon sufficiently addressing certain aspects of the institutional failures in the sector.

Genetic Characterization of Nile Tilapia (&amp;lt;i&amp;gt;Oreochromis niloticus&amp;lt;/i&amp;gt;) Strains from Senegal for Sustainable Local Aquaculture Production

The optimization of aquaculture production requires the selection of efficient strains. Thus, genetic improvement has become one of the important levers to boost the development of aquaculture. The objective of this study was to carry out genetic characterization of Nile tilapia Oreochromis niloticus, one of the most cultivated fish species in Senegal, in order to select an efficient strain to optimize local fish production. Thus, fish from five different populations (Richard-Toll, ANA, ITACA, Mbodiene and Sauvage) were analyzed, with 15 individuals per population. Genetic diversity and population structure were assessed using molecular genetic analyses by sequence characterized amplified region (SCAR) and microsatellite (SSR) markers. The analyses of the SCARII marker were conducted on four populations (ANA, ITACA, Sauvage and Mbodiene) while microsatellite analyses were conducted on all five populations. The results show high levels of polymorphism of SSR markers, and a high level of observed heterozygosity (Ho), indicating a high within-population genetic variability. These results are in agreement with the AMOVA results, which indicated a high within-population genetic variability (94%). The genetic structure analysis by DAPC indicates that the five populations analyzed are structured into four groups, which are highly heterogeneous because they share common allele individuals. The analysis of the genetic structure by AMOVA showed a low degree of differentiation between the populations (6%), in agreement with the genetic differentiation index (Fst = 0.059). The heterogeneity of studied populations implies a genetic flow over time, which may have existed between the original populations. The overall negative Tajima D values and low genetic differentiation indicate an excess of rare mutations in the populations studied, resulting from a recent population expansion from a limited number of initial breeders isolated in locale hatcheries. Thus, further studies with a much larger panel of markers are required to better differentiate the strains and identify the most efficient ones for sustainable local aquaculture production.

Partial replacement of fish meal with Moringa oleifera leaf meal in practical diets of Cirrhinus mrigala fingerlings.

Fish protein is serving as a source of nutrition for protein starving world. However, sustainable aquaculture products require inexpensive plant by-products due to finite sources of fish meal. Therefore, this study was conducted to examine nutrient utilization, growth performance and hematological indices of Cirrhinus mrigala fingerlings fed on Moringa oleifera leaf meal (MOLM) based diets. Fish were fed with six isonitrogenous and isoenergetic diets having MOLM as a substitute of fish meal (FM) at the levels of 0%, 10%, 20%, 30%, 40% and 50% for the period of 90 days. Fingerlings having initial weight 6.35±0.04g were reared in triplicate tanks at the stocking density of 15 and hand fed at the rate of 5% of total biomass twice regularly. Chromic oxide inclusion level was 1% in diets. After analysis, maximum growth performance and improved digestibility of nutrients were found in fish fed with diet at 10% replacement level as compared to fish fed on control diet and other test diets. Additionally, it was found that the red blood cells, white blood cells, hemoglobin and mean corpuscular hemoglobin concentration of fish showed a significantly (p<0.05) inverse correlation with the increase in MOLM. In present research, it was concluded that MOLM has good potential to be used as a FM substitute in C. mrigala diet with maximum effect at 10% showing positive hematological indices.

Bacterial Occurrence in Wild And Cultured Clarias Gariepinus From Yola, Adamawa State, Nigeria

An important cause of contamination in fisheries and aquaculture products is bacteria. They continue to be a major impediment towards obtaining sustainable fisheries and aquaculture production. They cause several public health hazards that producers, marketers, and consumers of food fish are deeply concerned about. The current study assessed the occurrence of bacteria in Clarias gariepinus from Yola, Adamawa state, Nigeria. Thirty (30) C. gariepinus were collected from the wild and a fish farm. Physicochemical measurements of the water were made at the time of the fish collection. The fish samples collected were transported to the laboratory for bacteriological analysis. Tissues were collected from the stomach, liver, and gills of the sampled fish and isolated for the occurrence of bacteria in them. The isolated bacteria were identified and characterized. The data that were collected were subjected to descriptive statistics analysis. The tissues of the examined C. gariepinus contained bacterial species including Escherichia coli, Staphylococcus aureus, Enterobacter aerogenes, Staphylococcus sp., Enterobacter cloacae, Streptococcus iniae, Citrobacter diversus, Proteus mirabilis, Klebsiella pneumoniae, Pseudomonas mallei, and Yersinia entrocolitica. The occurrence of these bacteria in the tissues of the fish samples examined raises possible public health concerns about fish and fish products from the lake and fish farm under investigation.

Silica-Gel Incorporated Biosynthesized-Silver Nanoparticles for Sustainable Antimicrobial Treatment of Brackish Water Aquaculture

Treatment of brackish water from pathogenic microbes is crucial for sustainable aquaculture production and preventing the spread of infectious diseases. However, the treatment of brackish water is still challenging due to the high salinity and the high antimicrobial resistance. Here, we exploit a facile and effective approach to synthesize silica gel embedded with silver nanoparticles (7–48 nm) for broad-spectrum antimicrobial activity. The incorporation of silver nanoparticles into silica gel (AgNPs@SG) is confirmed by flame atomic absorption spectrometry, X-ray diffraction, N2 physisorption, and transmission electron microscopy. The AgNPs@SG material exhibits wide-spectrum antimicrobial activity against the studied microorganisms (Pseudomonas aeruginosa, Escherichia coli, and Candida albicans) due to preventing the aggregation of silver nanoparticles and their effective contact with the microorganisms. Most importantly, the applicability of the synthesized AgNPs@SG for the microbial treatment of brackish water is investigated on different water samples collected from Manzala Lake. Remarkably, the amount of viable bacteria in the brackish water decreases by about 93% using AgNPs@SG material that not only combats antibiotic-resistant strains but also works under harsh conditions such as multiple-source contamination, high eutrophic state, and salinity.

Identification, characterization and nutritional regulation of fatty acid‐binding protein ( fabp ) genes by vegetable oils in European seabass ( Dicentrarchus labrax ) reared in low water temperatures

Dietary n-3 highly unsaturated fatty acids (HUFAs), which are low in vegetable oils (VO), are natural ligands of fatty acid-binding protein (fabp) genes, which function in molecular n-3 HUFAs metabolism in fish. Low water temperature (LWT) also affects fish fatty acid (FA) metabolism. Therefore, in this study, we investigated mRNA expression levels of fabp genes in European seabass (Dicentrarchus labrax) reared in LWTs. For this purpose, we cloned and characterized open reading frames of 10 fabp genes. Changes in the expression of fabp genes to VO-based diets for 60 days and fish oil (FO)-based diet for 30 days were determined. The present study's results suggest the following: (1) D. labrax fabp genes are orthologues of vertebrate fabp/FABP genes. (2) fabp1b.1/fabp1b.2 and fabp7a/fabp7b are retained in the D. labrax genome most likely because of the subfunctionalization. (3) The variation in tissue-specific expression of fabp10a/fabp10b and fabp11a/fabp11b paralogues also provides evidence of subfunctionalization; however, nutrigenomic results did not support this observation. Therefore, more detailed promoter analyses are needed to better understand their retentions in the D. labrax genome. (4) Feeding D. labrax with a FO-based diet following feeding with VO-based diets is insufficient for molecular FA metabolism recovery. This study is the first report on the characterization and nutritional regulation of fabp genes by dietary FAs in D. labrax reared in LWTs and suggests that transcriptional control of fabp genes by agonists would be helpful to maintain lipid homeostasis, protect fish health and increase fish welfare for sustainable aquaculture production.

Effectiveness of physical barriers and enhanced fertilization in controlling predation on tilapia and catfish aquaculture systems by four piscivorous water bird families

Waterbirds cause substantial fish-stock losses in open aquaculture systems, particularly in developing countries where fish-ponds are smaller and predator control methods largely manual or under-resourced. This study: (1) used three fish-pond treatment meassures to assess their efficiencies in deterring predation pressure by four piscivorous waterbird families in small tilapia and catfish farms in western Kenya; and (2) distinguished bird group(s) most effectively deterred by these measures. The treatment measures were: coarse-grid wire mesh barriers; finer-grid wire barriers; and enhanced pond fertilization. Twelve fish-ponds were randomly sampled to assess birds' pond-neigborhood assemblages and their predation deterrence responses to pond treatment effects. Bird species richness was not affected by pond cover status, enhanced pond fertilization or type of pond cover barrier. However, pond-cover status, singularly and interactively with enhanced fertilization, reduced bird encounter rates while cover barrier type did not. Conversely, cover status, cover barrier type and fertilization each separately but not interactively contributed to improved deterrence to bird predation rates overall. However, while predation by families of larger birds was effectively reduced by enhancing pond fertilization or cover barriers, predation by families of smaller birds was prevented only by fine-grid chicken-mesh barriers. These results demonstrate that using enhanced fertilization and physical barriers can significantly contribute to reduction in predation pressure on open-culture pond-fish by most piscivorous birds, but may not always be effective if used separately. Effectiveness of combination of measures chosen will depend on types of target bird species and their feeding habits. The results constitute additional knowledge on field techniques useful in diversifying solution options for minimizing impacts of vertebrate predation on pond-fish stocks toward promoting sustainable aquaculture production and improving rural human nutrition.

Future demand and supply of aquafeed ingredients: Outlines to commercialize non-conventional protein ingredients to enhance aquaculture production for food security in sub-Saharan Africa

AbstractAquaculture, being the fastest growing food sector, is expected to provide the highly needed animal protein for about 9.7 billion people globally by 2050. The world population is likely to consume 178 million tons of food fish/aquatic animals by 2028, whereby 58% of fish will likely be from aquaculture. Growth of food fish production is expected to increase overall production of aquafeeds to over 87 million tons by 2025. Aquafeed production relies largely on fishmeal which is getting expensive due to its multiple use and scarcity. A remedy to this situation is the use of non-conventional protein sources, which may be of plant (leaves, cereals, pulses etc.) or animal (insects, worms, etc.) origin. This paper demonstrates the potential of non-conventional ingredients for aquaculture. It was found that crude protein levels of selected non-conventional plant ingredients ranged from 25-71% while those of animal origin were from 66-72%. Inclusion levels of 5-40% and 25-66% were recommended in aquafeeds, respectively, from ingredients of plant and animal origin. Performances of fish fed aquafeeds containing selected non-conventional ingredients have been reviewed. Presence of anti-nutrients, chitin and high lipid in feed ingredients, and shortcomings in processing and mass production technologies, have been identified as the main challenges limiting the commercialization of the selected feed ingredients. To remove the unwanted factors and to enhance inclusion of non-conventional ingredients in aquafeeds, authors suggested varied strategies. The strategies such as defatting, heat treatment, extrusion cooking, solvent extraction, dehulling, fermentation, ensiling, genetic modification and inclusion of enzyme are identified as some of the most efficient methods. Effective and affordable technologies to improve nutritional value should be validated through research for adequate and consistent supply of aquafeed in Sub-Saharan Africa. Consequently, provision of sufficient, quality and affordable aquafeeds will promote sustainable aquaculture production and reduce fishing pressure and pollution in natural aquatic ecosystems.

Proteomic Applications in Aquatic Environment Studies.

Genome determines the unique individualities of organisms; however, proteins play significant roles in the generation of the colorful life forms below water. Aquatic systems are usually complex and multifaceted and can take on unique modifications and adaptations to environmental changes by altering proteins at the cellular level. Proteomics is an essential strategy for exploring aquatic ecosystems due to the diverse involvement of proteins, proteoforms, and their complexity in basic and advanced cellular functions. Proteomics can expedite the analysis of molecular mechanisms underlying biological processes in an aquatic environment. Previous proteomic studies on aquatic environments have mainly focused on pollution assessments, ecotoxicology, their role in the food industry, and extraction and identification of natural products. Aquatic protein biomarkers have been comprehensively reported and are currently extensively applied in the pharmaceutical and medical industries. Cellular- and molecular-level responses of organisms can be used as indicators of environmental changes and stresses. Conversely, environmental changes are expedient in predicting aquatic health and productivity, which are crucial for ecosystem management and conservation. Recent advances in proteomics have contributed to the development of sustainable aquaculture, seafood safety, and high aquatic food production. Proteomic approaches have expanded to other aspects of the aquatic environment, such as protein fingerprinting for species identification. In this review, we encapsulated current proteomic applications and evaluated the potential strengths, weaknesses, opportunities, and threats of proteomics for future aquatic environmental studies. The review identifies both pros and cons of aquatic proteomics and projects potential challenges and recommendations. We postulate that proteomics is an emerging, powerful, and integrated omics approach for aquatic environmental studies.