Farm-raised Fish Research Articles

Metabolomic and Lipidomic Tools for Tracing Fish Escapes from Aquaculture Facilities.

During adverse atmospheric events, enormous damage can occur at marine aquaculture facilities, as was the case during Storm Gloria in the southeastern Spanish Mediterranean in January 2020, with massive fish escapes. Fishes that escape were caught by professional fishermen. The objective of this study was to identify biomarkers in fish that enable differentiation among wild fish, escaped farm-raised fish, and farm-raised fish kept in aquaculture facilities until their slaughter. We focused on gilthead sea bream (Sparus aurata). We used nuclear magnetic resonance to search for possible biomarkers. We found that wild gilthead sea bream showed higher levels of taurine and trimethylamine-N-oxide (TMAO) in their muscle and higher levels of ω-3 fatty acids, whereas farm-escaped and farmed gilthead sea bream raised until slaughter exhibit higher levels of ω-6 fatty acids. From choline, carnitine, creatinine, betaine, or lecithin, trimethylamine (TMA) is synthesized in the intestine by the action of bacterial microflora. In the liver, TMA is oxidized to TMAO and transported to muscle cells. The identified biomarkers will improve the traceability of gilthead sea bream by distinguishing wild specimens from those raised in aquaculture.

Dietary calcifediol reduces mesenteric adiposity to the benefit of carcass growth independently of circulating vitamin D hormone in juvenile Atlantic salmon

Dietary vitamin D is required by cultivated fish for optimal growth, feed utilisation and bone health. The in vivo conversion of cholecalciferol (D3) to active vitamin D hormone (1,25-OH-D3) may be impaired in farm-raised fish fed modern feed formulations. Requiring fewer metabolic steps for its conversion, the use of dietary calcifediol (25-OH-D3) may mitigate against deficits in vitamin D metabolism.A 90-day experimental feeding trial was undertaken in juvenile (23 g) Atlantic salmon (Salmo salar) to test the efficacy of 25-OH-D3 added to a standard diet containing recommended levels of D3 (5640 IU). Test diets contained 100, 200 or 400 μg/kg added 25-OH-D3 against a no additive control diet. Effects on zootechnical performance, indices of adiposity, bone mineralisation, and circulating vitamin D metabolites were tested.Dietary 25-OH-D3 significantly reduced feed conversion ratio (FCR) and resulted in numerical increases in growth performance. 25-OH-D3 also significantly reduced mesenteric adiposity with concurrent increases in carcass weight. Levels of calcium, phosphorous, magnesium, zinc and manganese were not modulated in the vertebrae of fish receiving 25-OH-D3. Circulating 25-OH-D3 remained below detection limits and 1,25-OH-D3 was not significantly modulated by the dietary manipulations.The significant reduction of mesenteric adiposity to the benefit of carcass weight shows that dietary 25-OH-D3 improves the utilisation of lipids. The vitamin D requirement for bone mineralisation was met by the basal diet. Segmented regression estimates a dietary 25-OH-D3 supplementation of 143 to 180 μg/kg for improved feed conversion and reduced mesenteric adiposity. The lack of correlation between circulating vitamin D hormone and mesenteric adiposity indicates that lipid metabolism is regulated by localised tissue activation of vitamin D, rather than the endocrine functions of circulating 1,25-OH-D3.

Nutritional composition, bacterial load and organoleptic quality of farm-raised catfish(<i>Clarias</i> <i>gariepinus</i>, burchell 1822) from the Dormaa Municipality, Ghana

The aim of this study was to assess the quality of farm-raised African catfish (<i>Clarias</i> <i> gariepinus<i>, Burchell, 1822) in the Dormaa Municipality, Ghana. Thirty (30) individuals of freshly harvested fish of average weight 912.78±16.43 g obtained from a fish farm and anequal number of smoked farm-raised fish of average weight 769.19± 6.48 g were used for the study. The mean values obtained for the proximate analysis of fresh catfish were: moisture (77.4 ± 1.94 %), ash (1.34 ± 0.26 %), fat (0.57 ± 0.17 %), protein (17.58 ± 0.23 %) and total carbohydrate (4.45 ± 1.55 %) and those for the smoked fish were: moisture (11.63 ± 0.43 %), ash (7.06 ± 0.66 %), fat (9.31 ± 1.80 %), protein (25.72 ± 1.51 %) and 53.34 ± 0.15 % for total carbohydrate. The overall acceptability of fresh and smoked farm-raised catfish ranged from 3.2-4.6 and 3.0-3.8 respectively. There were significant differences (P < 0.05) in the nutritional, bacterial and organoleptic qualities between the fresh and smoked catfish. Results from the study revealed higher nutritional composition in smoked catfish and lower bacterial loads in both fresh and smoked fish except E. coli, which must be of concern for consumer safety. It is recommended that farmed catfish should be smoked before consumption to obtain maximum nutritional benefit.

Comparison of skin mucus lectins among longtooth grouper Epinephelus bruneus and giant grouper E. lanceolatus as well as the hybrid, Kue-Tama, and their binding abilities to the skin fluke Benedeniaepinepheli

Interspecific hybrids of farm-raised fish are becoming popular in aquaculture owing to their advantages over pure species, including improved growth and higher resistance to infectious diseases. Kue-Tama is a recently established hybrid grouper derived from the longtooth grouper Epinephelus bruneus (♀) × giant grouper E. lanceolatus (♂). In our previous study, this hybrid showed significantly higher resistance against the skin fluke Benedenia epinepheli, a problematic parasite in grouper farming, than the longtooth grouper. In the present study, we explored lectins in the skin mucus of hybrids and their parent species. While C-type lectins of approximately 15 kDa were obtained from longtooth groupers, additional C-type lectins with molecular masses of approximately 20 and 30 kDa, as well as 45-kDa F-type lectin, were also detected in Kue-Tama and giant groupers. Semi-quantitative reverse transcript-polymerase chain reaction (RT-PCR) demonstrated that the gene expression levels of both C-type and F-type lectins were significantly higher in the skin of the hybrid and giant groupers than that of the longtooth grouper. In addition, some skin mucus lectins of the hybrid and giant groupers were bound to the fluke, suggesting that these lectins conferred resistance to parasitic infections.

Multidrug-resistant phenotypes among biofilm-producing staphylococcal isolates from farm-raised fish: a molecular scrutiny.

To describe the molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolates from farm-raised fish. Fish samples (n=180) collected from aquaculture farms in three major districts of Kerala, yielded 45 methicillin-resistant staphylococci (MRS) (25%) isolates. All of the isolates were resistant to tested beta-lactams, and 19 (42.22%) were resistant to flouroquinolones. According to the resistance profile of each isolate, 33 of 45 (73.33%) are identified as multidrug-resistant (MDR) isolates, with an average multiple antibiotic resistance (MAR) index of 0.41±0.09. Notably, virulence determinants such as classical enterotoxin (sea & seb), and SE-like toxin (seg & sei) genes co-existed with Antimicrobial Resistance Genes (ARGs) in isolates studied. Regardless of the isolates being strong biofilm producers, only 23 (51.1%) harbored icaA and icaD genes. The heterogeneity of MRSA (n=17) clones were evident as the species belonged to three major spa types (t345, t2526, and t1309) and sequence types (STs), viz., ST772, ST88, and ST672. The current study on molecular characterization of the MRS isolates sheds light on the preventive measures that need to be implemented to limit the spread of AMR pathogens in aquaculture.

Dietary uptake of geosmin in rainbow trout (Oncorhynchus mykiss)

Geosmin is a primary source of muddy/earthy ‘off-flavors’ in farmed fish, which may render their organoleptic quality unacceptable to consumers. Model systems of geosmin uptake typically comprise exposure to waterborne geosmin that is absorbed via the gills. The present research demonstrates dietary exposure as an alternative route of geosmin uptake in Rainbow Trout (Oncorhynchus mykiss) fillets. Trout (average initial weight of 355 g) were stocked in quadruplicate compartmentalized raceways (N = 4 compartments per treatment, n = 50 fish per compartment) supplied with first-use, flow-through water (4.5 complete turnovers per hour). Fish were fed diets containing 0 (control dose), 0.005 (low dose), 0.05 (medium dose), or 0.5 (high dose) mg geosmin/kg feed at 1% body weight/day for four weeks. Fillets (12 fillets/diet/week plus 12 pre-trial fillet samples) and weekly feed and water samples were analyzed via GC–MS to determine geosmin concentrations. Feeding behavior was documented daily according to a four-point scale. ANOVA with post-hoc Tukey tests and polynomial contrast, regression, correlation, and chi-squared statistical analyses were applied to data (α = 0.05 significance level). Palatability of feed did not hinder consumption of the geosmin-spiked feeds: although fish responded positively to all feeds, the most aggressive feeding behavior was observed among those fed medium and high dose feed. Geosmin was effectively imparted into fillets after one week, and no significant temporal effect was found after four weeks. Mean geosmin concentrations significantly increased in fillets from low (mean of 26 ng/kg geosmin) to medium (202 ng/kg) to high (441 ng/kg) dose feed groups during the trial. Polynomial contrasts and regression modeling validated this significant positive effect of dose on geosmin uptake, with an estimated 166 ng/kg rise in fillet-geosmin for every log10 increase in feed concentration. Waterborne geosmin levels immediately post-feeding were conditionally independent of concentrations in feed and fillets, therefore dietary uptake was affirmed as the predominant mechanism of absorption in the present experimental system. Based on these findings, geosmin-spiked feeds may be used to induce predictable, repeatable levels of this off-flavor compound in fillets and serve as a model system for further investigation of sensory quality and off-flavor mitigation strategies for farm-raised fish.

Antimicrobial Resistant Bacteria Monitoring in Raw Seafood Retailed: a Pilot Study Focused on Vibrio and Aeromonas.

In aquaculture, bacterial infections in sea animals are treated using antimicrobials. As seafood is frequently consumed in its raw form, seafood contaminated with water-borne antimicrobial-resistant bacteria presents a potential transmission route to humans and can influence food safety. In this study, we aimed to determine the abundance of water-borne bacteria in retail raw seafood and to characterize their antimicrobial resistance profiles. In total, 85 retail raw seafood samples (32 fish, 26 shellfish, 25 mollusks, and two crustaceans) were purchased from supermarkets in Japan, and water-borne bacteria were isolated. The isolated bacterial species predominantly included Vibrio spp. (54.1%) and Aeromonas spp. (34.1%). Vibrio or Aeromonas spp. were isolated from more than 70% of the seafood samples. Tetracycline-, sulfamethoxazole-, and/or trimethoprim/sulfamethoxazole-resistant Vibrio or Aeromonas spp. isolates were detected in seven (21.9%) fish samples (two wild-caught and five farm-raised) harboring tet, sul, and/or dfr genes. Sulfamethoxazole- and trimethoprim/sulfamethoxazole-resistant isolates were only detected in farm-raised fish. Tetracycline and sulfamethoxazole are commonly used in aquaculture. These results suggest that water-borne bacteria like Vibrio and Aeromonas spp. should be the primary focus of antimicrobial-resistant bacteria monitoring to effectively elucidate their spread of bacteria via seafood.

Role of phytobiotics in relieving the impacts of Aeromonas hydrophila infection on aquatic animals: A mini-review.

Aeromonas hydrophila is a ubiquitous bacterium with various hosts that causes mass mortality in farm-raised fish species and significant economic losses. The current antibiotic treatment is ineffective in controlling this bacterium infection in aquaculture species. Therefore, an evaluation of potential phytobiotics is needed to find an alternative antimicrobial agent to reduce the over-reliance on antibiotics in aquaculture and safeguard public and environmental health. Furthermore, the rise in antibiotic resistance cases among pathogenic bacteria indicates an urgent need for new fish and shellfish health management solutions. In this context, phytobiotics applications in aquaculture can be defined as any medicinal plant-based antimicrobial agent used in fish and shellfish health management. This review will focus on the impacts of Motile Aeromonas Septicemia (MAS) due to A. hydrophila in aquaculture, the potential of phytobiotics in enhancing the tolerance of aquaculture species against MAS and the combination of phytobiotics with other antimicrobial and therapeutic agents against MAS.

Radiological risk assessment of farm-raised fish species due to natural radionuclides in the freshwater ecosystem of Bangladesh with the statistical approach

We study radiation exposure resulting from the consumption of farm-raised freshwater fish species that form an essential part of the Bangladeshi diet. The levels of radioactivity in the human diet are of particular concern, requiring assessment of possible radiological risks to human health. Therefore, a comprehensive study was carried out to determine the radioactivity levels (226Ra, 228Ra, and 40K) in fifteen commonly available varieties of farm-raised fishes. The gamma-ray spectroscopic analysis showed the presence of radionuclides of 226Ra, 228Ra, and 40K in all studied fishes, but varying degrees. The highest radioactivity levels of 226Ra, 40K, and 228Ra were observed in Rui (Labeo rohita) and Tilapia (Oreochromis mossambicus) with values of 8.50 ± 0.30, 513.28 ± 1.59, and 7.41 ± 0.15 Bqkg−1, respectively. The respective radioactivity levels were lowest in Silver carp (Hypophthalmichthys molitrix), Mola (Amblypharyngodon mola), and Koi (Anabas testudineus) with values of 0.83 ± 0.38, 171.07 ± 1.60, and 0.62 ± 0.30 Bqkg−1. The doses for 226Ra, 228Ra, and 40K due to consumption of a kilogram of farm fish were assessed and range from 5.56 (Sarputi – Puntius sarana) to 54.36 µSvy–1 (Rui – Labeo rohita), 9.77 (Koi – A. testudineus) to 116.79 µSvy–1 (Tilapia – O. mossambicus), and 24.23 (Mola – A. mola) to 72.69 µSvy–1 (Rui – Labeo rohita), respectively. In most cases, the estimated probability of an increase of cancer risk from daily intake of the farm-raised fish diet representing a minor fraction of ICRP values. Statistical analysis shows that the radioactivity and estimated radiological parameters are strongly correlated with 226Ra and 228Ra, while weakly correlated to 40K, suggesting that radiological risk is basically associated and controlled by the activity levels of uranium and thorium series radionuclides.

Herbivorous fish (Medialuna ancietae) as a sustainable alternative for nutrition security in Northern Chile

Sustainability in aquaculture is a necessity of the future, not only as the most promising means of supplying the protein that the world will require to feed its growing population but to offer needed conservation of the world’s ocean resources. The use of wild fish inputs in farm-raised fish outputs has been a primary concern of sustainability in aquaculture production. Herbivorous fish are more efficient converters of protein into fish flesh. Species of the genus Medialuna fish have been reported as a fast-growing, short-lived species. The native fish Acha (Medialuna ancietae Chirichigno 1987) in the Northern part of Chile is an over-exploited fish that has been associated with aquatic vegetation as a food source. We studied the feeding habits and nutritional composition of M. ancietae. For this, we developed a reference collection of marine macroalga (epidermis and nutritional composition) observed in the diet of individuals of this species for the study of digestive material. More than 90% of the components found were marine macroalgae, indicating that M. ancietae is an herbivorous fish. Compared to non-herbivorous fish our results showed that most of the nutrients present in the Medialuna diet are found at much lower levels including n-3 long-chain polyunsaturated fatty acids (49.7%) and protein (13–60%). M. ancietae meat provides essential components of human nutrition with a significant protein content (18.99 ± 0.26%) and 268 ± 5.9 mg/100 g of the essential n-3 long-chain polyunsaturated fatty acids. Most fed aquaculture non-herbivorous species rely on wild-captured fish for these essential nutrients, while M. ancietae can obtain and concentrate them from potentially cultivable macroalgae. M. ancietae has potential for sustainable aquaculture production as a contribution to nutrition security and the re-stocking of wild populations.

Salmonids as Natural Functional Food Rich in Omega-3 PUFA

Salmonids are valuable fish in the human diet due to their high content of bioactive omega-3 very long-chain polyunsaturated fatty acid (VLC PUFA). The aim of this study was to assess the omega-3 VLC PUFA content in selected salmonid fish present on the food market regarding whether they were farm-raised or wild. It was assumed that farm-raised fish, by eating well-balanced feed enriched with omega-3 PUFA, might contain omega-3 VLC PUFA in levels similar to that of wild fish. Fat content, fatty acid composition and omega-3 VLC PUFA content in fish fillets were measured. Farm-raised salmon from Norway, wild Baltic salmon, farm-raised rainbow trout and brown trout were bought from a food market whereas wild trout (rainbow and brown) were caught alive. The fat content in fish ranged from 3.3 to 8.0 g/100 g of fillet. It was confirmed that although wild salmonid fish contain 10–25% more omega-3 VLC PUFA in lipid fraction, the farm-raised ones, due to the 60–100% higher fat content, are an equally rich source of these desirable fatty acids in the human diet. One serving (130 g) of salmonid fish fillets might provide a significant dose of omega-3 VLC PUFA, from 1.2 to 2.5 g. Thus, due to very high content of bioactive fatty acids eicosapentaenoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) in their meat, salmonid fish currently present on the food market, both sea and freshwater as well as wild and farm-raised, should be considered as natural functional food.

Phylogenetic characteristics of selected European huchen (Hucho hucho L.) broodstocks – implication for broodstock management

Abstract European huchen (Hucho hucho) is a representative of large and rare migratory salmonid fish, which has become endangered due to extensive anthropogenic changes in freshwater ecosystems. Numerous broodstocks of the European huchen have therefore been established throughout the species’ range in recent years to supplement wild fisheries of this species. Unfortunately, this conservation management strategy entails a number of potential ecological and genetic risks associated with the release of farm-raised fish into wild populations. A comprehensive and feasible genetic monitoring protocol for broodstocks maintained for the production of restocking material is therefore essential in the sustainable management of critically endangered fish species. The current paper presents phylogenetic characteristics of four selected huchen broodstocks across Central and Eastern Europe. Genetic comparisons of the studied broodstocks were based on ten microsatellite DNA markers. The effective population size (Ne), the individual assignment test, the Principal Coordinates Analysis (PCoA), the allele sharing distance (DAS) and the Bayesian clustering analysis were applied in this study. Moreover, five selected fragments of mitochondrial DNA were used for molecular verification of species membership and genetic purity of examined specimens.

Hybrid multi-criteria decision-making approach to select appropriate biomass resources for biofuel production

Biofuel generation from local biomass resources can significantly contribute to greenhouse gas mitigation and cleaner energy production. In this regard, a hybrid Multi-Criteria Decision-Making (MCDM) approach was employed to prioritize appropriate biomass resources for biofuel production. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Additive Ratio Assessment (ARAS), and Weighted Aggregates Sum Product Assessment (WASPAS) were the employed MCDM approaches. Subsequently, ranking aggregation methods, i.e., Borda, Copeland, and Rank Mean, were applied to integrate the rankings obtained from the MCDM approaches. Guilan province of Iran was selected as a case study based on its promising potential for biofuel production from first-, second-, and third-generation biofuel resources. Initially, through an in-depth review of the literature and the use of academic professors' expert opinions, ten criteria were selected as the evaluation indices of the study: 1) creating technical side jobs, 2) preserving non-renewable energy resources, 3) relative advantage of biofuel production, 4) complexity of biofuel production process, 5) cost of the biomass conversion process, 6) biomass reusability, 7) cost of biomass supply, 8) environmental impacts of biomass accumulation, 9) adaptability of the biofuel production process to the size of biomass production units and the attitude and knowledge of the producers, and 10) energy self-sufficiency of the biomass producer. Moreover, the 11 investigated potential sources of biofuel production were rice, peanut, livestock and poultry wastes, rice waste, peanut waste, tea residues and its processing wastes, olive residues and its processing wastes, livestock and poultry slaughter and farm-raised fish wastes, municipal solid waste and sewage, forest and wood farming wastes, algae and Azolla. The results indicated that “municipal solid wastes and sewage”, “forest and wood farming wastes” and “livestock and poultry wastes” from the second-generation biofuels were identified as the most important biomass resources in the studied area.

Nutrition and Functions of Amino Acids in Fish.

Aquaculture is increasingly important for providing humans with high-quality animal protein to improve growth, development and health. Farm-raised fish and shellfish now exceed captured fisheries for foods. More than 70% of the production cost is dependent on the supply of compound feeds. A public debate or concern over aquaculture is its environmental sustainability as many fish species have high requirements for dietary protein and fishmeal. Protein or amino acids (AAs), which are the major component of tissue growth, are generally the most expensive nutrients in animal production and, therefore, are crucial for aquatic feed development. There is compelling evidence that an adequate supply of both traditionally classified nutritionally essential amino acids (EAAs) and non-essential amino acids (NEAAs) in diets improve thegrowth, development and production performance of aquatic animals (e.g., larval metamorphosis). The processes for the utilization of dietary AAs or protein utilization by animals include digestion, absorption and metabolism. The digestibility and bioavailability of AAs should be carefully evaluated because feed production processes and AA degradation in the gut affect the amounts of dietary AAs that enter the blood circulation. Absorbed AAs are utilized for the syntheses of protein, peptides, AAs, and other metabolites (including nucleotides); biological oxidation and ATP production; gluconeogenesis and lipogenesis; and the regulation of acid-base balance, anti-oxidative reactions, and immune responses. Fish producers usually focus on the content or digestibility of dietary crude protein without considering the supply of AAs in the diet. In experiments involving dietary supplementation with AAs, inappropriate AAs (e.g., glycine and glutamate) are often used as the isonitrogenous control. At present, limited knowledge is available about either the cell- and tissue-specific metabolism of AAs or the effects of feed processing methods on the digestion and utilization of AAs in different fish species. These issues should be addressed to develop environment-friendly aquafeeds and reduce feed costs to sustain the global aquaculture.

Sustainability indicators for sustainably-farmed fish in Bangladesh

To be sustainable, farmed fish should be environmentally suitable, biologically ideal, socially acceptable and economically viable. As these sustainability indicators (SIs) strongly influence consumers’ fish purchase intent, farms should report them as a balanced source of sustainability information. However, in the literature, little attention has been paid to biological indicators in assessing aquaculture sustainability, nor to the extent of the SIs. Furthermore, the assessed SIs have not been examined by consumers. Therefore, this study measures consumers’ perceived value of these. Consumers’ sustainability knowledge and attitude towards farm-raised fish are also taken into account. Multinomial logit and basic latent class logit models are employed, together with a direct survey of households in Bangladesh. The results demonstrate that a low level of water use and appropriate feeding in the production process (e.g., environmental and biological indicators) of farmed fish increase consumers’ utility and that they are willing to pay a price premium for these attributes. Consumers look for the ‘safety label’, which indicates intermediately, averagely, and fairly sustainable farmed fish. Initially, consumers prefer averagely sustainable fish, but when they eat a high amount of farmed fish in their total fish consumption, they are more likely to prefer fairly sustainable ones, which are high sustainable. Therefore, the study results indicate that produced fish should be marketed with environmental and biological sustainability indicators, including food safety labels. Additionally, a close monitoring system will increase social acceptability, leading to sustainable fish farming and consumption.

Social license and consumer perceptions of farm-raised fish

This study uses personal predispositions, attitudes towards food industry actors, media use and food consciousness as variables to explore trust in farm-raised and the degree to which respondents believe that aquaculture benefits their home state. The authors use a random sample mail survey of primary food shoppers in Wisconsin, a state in the Great Lakes region of the United States, where aquaculture is considered an emerging industry and fish sold for food are generally raised in manmade ponds or flow-through raceways. They find that trust in government agencies, grocery stores, food manufacturers/processors, perceived industry environmentalism and attention environmental news, were positively related to both trust in fish farmers and perceptions that benefits from fish farming accrue within the state. Although attention to environmental news and conservative ideology were positively related to trust in fish farmers, and a preference for GMO-free/organic foods was negatively related to the same, none of these three variables had a relationship to the perception that fish farming benefits the respondents' state. Implications are discussed.

Analysis of Organoarsenic Compounds Concentration in Fish with the Newly Developed LC-MS/MS Method

Most fish contain some kinds of organoarsenic compounds. To assess the health risk for the chronic effects due to intake of these compounds, it is necessary to quantify the concentration of each chemical form, since the toxicity is difference depending on the form. We developed and validated the LC-MS/MS method to determine the concentration of monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA), arsenobetaine (AB), and arsenocholine (AC) in fish. Using this method, we quantified the concentration of each organoarsenic compounds and total arsenic in 50 fish samples from across 10 groups. Total arsenic concentration ranged from 0.53 to 25 mg/kg in all samples, except for in thread-sail filefish where the concentration ranged from 8.3 to 25 mg/kg. With the exception of sardines, in all samples AB was found at the highest level in relation to the total arsenic concentration. In sardines, the concentration of DMA was higher than that of AB, accounting for 16 to 24% of total arsenic. In red sea bream, concentrations of total arsenic, AB, and AC in farm-raised fish were lower than those in wild-caught fish.

Consumer Preferences for Fish Attributes in Bangladesh: A Choice Experiment

Over the last decade, there has been a rapid increase in aquaculture in South and Southeast Asia, and both domestic and imported farm-raised fish are now readily available in local markets. However, few consumer studies of fish preferences have been conducted in South and Southeast Asian markets. A choice experiment was conducted at the consumer level in three cities, and the data were analyzed with a mixed logit model in willingness-to-pay space. The results showed that on average, consumers were willing to pay more for indigenous than for foreign fish species. Furthermore, they preferred domestic to imported production and fresh to frozen fish. However, Bangladeshi consumers were not willing to pay a significant premium for wild-caught fish. The lack of consumer differentiation in regard to the production method is promising for aquaculture in this region and provides hope for reducing the pressure on wild fisheries.

Market potential for Gulf of Mexico farm-raised finfish

Concerns that additional supplies of U.S. farm-raised fish may compete with domestic wild fish has contributed to resistance and litigation that has slowed aquaculture development in the U.S. We employ a contingent choice experiment to large seafood wholesalers and suppliers in the U.S. to investigate market potential of new farmed finfish species from the Gulf of Mexico. We estimate probabilities that wholesale buyers prefer a new farmed product over existing market products using a conditional logit model. The results indicate it is more probable that Gulf farmed fish will substitute for imports than for domestic wild-caught fish given U.S. wholesale buyers have a preference for domestic fish to imported fish, but no significant preference for wild-caught fish to farmed fish.

Primary amino acids affect the distribution of methylmercury rather than inorganic mercury among tissues of two farmed-raised fish species

The distributions of primary amino acids, MeHg and IHg in body tissues of two commonly farm-raised fish species (common carp: Cyprinus carpio; grass carp: Ctenopharyngodon idellus) in Guizhou Province, SW China, were investigated to understand the effects of primary amino acids on MeHg and IHg metabolism in farm-raised fish. The primary amino acids were classified into four groups: (1) essential and polar amino acids; (2) essential and non-polar amino acids; (3) non-essential and polar amino acids; and (4) non-essential and non-polar amino acids. For both fish species, groups (1, 2 and 3) were enriched in muscle and kidney, whereas group (4) was enriched in scale. The two fish species showed low MeHg concentrations (grass carp: 0.5–3.9 ng/g; common carp:1.0–7.4 ng/g) and low MeHg proportions (grass carp: 2–45%; common carp: 6–37%) in their tissues, which are mainly due to the simple food web structures and the fast growth of the farm-raised fish. Positive correlations (r = 0.342 to 0.472; p < 0.01; n = 78) were observed between MeHg and several primary amino acids (cysteine, threonine, phenylalanine, leucine, valine, glutamate serine and tyrosine) in fish tissues, which may be driven by the formation of MeHg-Cys complexes within fish body. However, no significant correlations were observed between IHg and any primary amino acids, indicating the metabolic processes of IHg and MeHg are different. This study advances our understanding that cysteine and its related/derived amino acids may be an important driving force for MeHg distribution and translocation in fish.