In triangle sail mussel (Hyriopsis cumingii), shell biomineralization is a complicated process that involves multiple gene products. Shell matrix proteins are involved in the formation of the organic framework and play an important role in the regulation of calcium carbonate deposition. In this study, A new shell matrix protein gene Hc-transgelin was identified in H. cumingii. The full-length cDNA of Hc-transgelin was 1200 bp, including a 501 bp open reading frame, which encoded 166 amino acids. Hc-transgelin is rich in lysine, it accounts for 11.40% of the protein. The predicted transgelin protein contained a conserved calmodulin homologous domain. A tissue-specific expression assay indicated that Hc-transgelin exhibited significantly highest expression in the mantle. Furthermore, Hc-transgelin in situ hybridization detected positive signals at the edge of the mantle outer fold, where nacre and prismatic layer biomineralization occur. An RNA interference assay showed that the shape of aragonite flakes in nacre changed and their growth was inhibited, and cracks appeared in the prismatic layer organic sheath when the expression of Hc-transgelin was suppressed. In a shell repair assay, a higher expression of Hc-transgelin appeared from day 12 to day 25 when the nacre accumulated quickly. These findings indicate that Hc-transgelin may be involved in the formation of aragonite flakes in the nacre and play a role in the formation of the organic sheath in the prismatic layer of the shell. This study provides new insights into the role of the Hc-transgelin gene and also contributes to the molecular understanding of mollusk shell formation.

The growth of aquaculture demands intense consumption of formulated foods, scarce natural resources such as water and land. The increase in aquaculture production needs to be sustainable in several aspects of the activity, including the use of more sustainable farming systems that provide reduced water demand, less space dependence for increased production, and availability of complementary natural food. In this perspective, the biofloc system (BFT), presents itself as a more friendly cultivation technology as a way to mitigate some impacts of aquaculture production. Much research has been carried out, addressing different aspects important to the production of fish in BFT. In this review, we address how stocking density, carbon sources and carbon nitrogen ration (C/N) affect animal performance and the nutritional value of bioflocs; the use of microbial aggregates as “in situ” and “ex situ” food and the benefits in feed conversion, and their influence on the immune system and disease resistance.

This study was aimed at preparing chitosan (CS)-phenolic acids copolymers to obtain better preservation effect in marine products. In this work, CS was grafted onto phenolic acids such as gallic acid (GA) and protocatechuic acid (PA) by a carbodiimide coupling method. The copolymers (CS-grafted-GA (CS-g-GA) and CS-grafted-PA (CS-g-PA)) were further confirmed through physicochemical properties including ultraviolet–visible (UV–Vis) spectrophotography, fourier transform infrared (FTIR) spectrometry, differential scanning calorimetry (DSC) thermogram, rheological behaviour, scanning electron microscope (SEM) and antioxidant activity analysis. Subsequently, the effects of copolymers on preservation of refrigerated sea bass (Lateolabrax japonicus) fillets were investigated. The results showed that the CS-g-GA (110.82 mg GA/g) exhibited higher grafting rate than CS-g-PA (62.63 mg PA/g). According to the assessment of UV–Vis and FTIR spectrometry, both the GA and PA were grafted onto CS successfully. SEM analysis demonstrated that the microstructure of copolymers became irregular. Meanwhile, both the CS-g-GA and CS-g-PA copolymers displayed superior thermal stability, rheological properties and antioxidant capacity than the pure CS. Furthermore, the copolymers also revealed a significantly stronger preservation effect on sea bass fillets including inhibiting microbial growth and delaying the deterioration of color, texture and sensory quality. Therefore, CS-g-GA and CS-g-PA could be used as promising preservatives for seafood.

The butter catfish, Ompok bimaculatus, belonging to the silurid family, is widely regarded as an important food fish for aquaculture diversification in India. Furthermore, the species poses a threat due to habitat degradation and other anthropogenic factors, and has been categorised as “near threatened”, therefore, its culture promotion is warranted. To establish a successful breeding programme, a precise understanding of the life history, and biology (reproductive/feeding) of the fish will assist hatchery managers and researchers. Studies in these areas have been undertaken by several groups over the years, but without much coherence, the data are still fragmented. Few attempts on the culture attributes of this catfish have been performed under both mono- and polyculture systems to bring about parallel promotion through aquaculture in a larger part of the subcontinent. Highlighting this, we have tried to analyse and present a consolidated account of the morphological characteristics, feeding habits, reproductive biology, early developmental ontogeny, and culture potentials of O. bimaculatus in India. This review was also prompted by the paucity of information on the cultural aspects of the species. Additionally, based on the reported studies, future directions and perspectives of the culture promotion of the species are proffered to ensure future research initiatives.

Frozen storage of emulsion-type sausages may be one approach to avoid or reduce the use of sodium nitrite, which is associated with health risks. Silver carp (Hypophthalmichthys molitrix) mince (M0) was washed for 1 (M1) or 3 (M3) times and the impact of washing on the properties frozen storage (−18 °C) during 4 months were determined and results were compared to those of conventional silver carp sausages (Mt). Lipid oxidation, as evidenced by changes in thiobarbituric acid reactive substances and FFAs, took place during storage in the order of M0 > M1 = M3 = Mt with M0 being highly oxidized (P ≤ 0.05). Total volatile base nitrogen formed during storage and the ranking for the quality loss was as follows M0 > M1 > M3 = Mt. Washing (M1 = M3) led to less hardness (P ≤ 0.05). Mt had better redness, while M1 and M3 led to higher expressible moisture, water release and lightness (P ≤ 0.05). Results indicated the lower sensory and consumer-liking properties of frozen M1 and M3 sausages. Therefore, washing and frozen storage influenced silver carp mince sausages.

The mud crab Scylla paramamosain is a key species in China due to its high nutritional value and great economic worth and has grown in popularity. Myo-inositol can modulate versatile physiological functions in aquatic animals. In the present study, S. paramamosain megalopa were given graded concentrations of myo-inositol (0, 1, 2, 4, and 8 ppm) by water immersion to explore how their metamorphosis would be affected. The results showed that supplementing with myo-inositol remarkably increased transformation and survival rate from megalopa to crablet by at least 1.16 and 1.26 times, respectively. To decipher the molecular mechanism of how myo-inositol increases metamorphosis and survival rate, we further performed transcriptome-based gene expression profiling of both megalopa and crablet treated with myo-inositol. The integrative transcriptome analyses predicted that the differentially expressed genes (DEGs) were significantly enriched in chitinase activity, structural constituent of cuticle, and chitin binding, which are associated with the decomposition and reconstruction of cuticle. qPCR results confirmed that myo-inositol mediated gene expression levels of the above cuticle-related pathways. Considering the importance of the cuticle in exoskeleton formation and molting, it can be concluded that myo-inositol-induced changes in the cuticle decomposition and reconstruction might have accelerated the transformation from megalopa to crablet of S. paramamosain. Besides, numerous DEGs were significantly enriched in protein digestion and absorption, amino sugar and nucleotide sugar metabolism. It implies that myo-inositol may improve survival by regulating energy or nutrient absorption. Additionally, the accelerated metamorphosis by myo-inositol may improve survival from megalopa to crablet of S. paramamosain. Overall, this study will provide the first insights into the underlying molecular mechanisms by which myo-inositol increases metamorphosis and survival.

China is the most productive seaweed farming country in the world and her seaweed imports and exports have a significant impact on global seaweed trade commodities and food security. Nevertheless, few studies had delved into the main characteristics and development of China's seaweed farming industry. This paper aims to narrow this research gap by analyzing trade patterns in China's seaweed products and the international competitiveness of seaweed product by using the international market share index (IMS), the trade competitiveness index (TC), and revealed comparative advantage index (RCA) from 2002 to 2017. The results showed that Japan, the Association of Southeast Asian Nations (ASEAN), Chile, Peru, and the Republic of Korea are China's main trade partners, the total trade value of China's seaweed products has grown rapidly, its imports have gradually exceeded exports, the trade deficit continues to expand, and its competitiveness keeps decreasing. The reasons for this trend may include the changing seaweed trade commodity structure, product differentiation, increased government support in competing countries, and trade barriers among the trade partners. We propose actively expanding international trade markets, establishing a strong seaweed product processing industry to develop high value-added seaweed products, optimizing the trade commodity structure, and differentiating of seaweed products to improve the competitiveness of China's seaweed products.

An 8-week feeding trial investigated the optimum dietary vitamin K3 requirements of largemouth bass. A total of 600 healthy fish (12.96 ± 0.07 g) were fed diets containing varying levels of vitamin K3 at 0.78 (K0), 5.80 (K5), 10.82 (K10), 15.84 (K15), and 20.85 (K20) mg/kg with four replicates per level. Results showed that dietary vitamin K3 enhanced growth, with weight gain rate and specific growth rate in K15 trials significantly higher than K0 trials (P  0.05). However, the supplementation of vitamin K3 significantly contributed to calcium accumulation in muscle tissues and vertebrae (P  0.05). The antioxidant capacity was improved with the addition of vitamin K3, which was inconsistent with the changes in malondialdehyde and MK-4 (a form of menaquinone) within liver and serum, suggesting that the toxicity of excessive artificial vitamin K3 may account for this difference. Using regression analysis, the appropriate dietary vitamin K3 levels within a largemouth bass diet was determined to be in the range of 9.93–15.22 mg/kg, which will provide a reference for the preparation of vitamin premix and artificial diet for largemouth bass.

Occurrence of biogenic amines in fresh fish and fishery products constitute a significant safety concern. Ingestion of histamine is identified as the causative agent of several food poisoning incidences on an annual basis. In addition, cadaverine, putrescine and tyramine have been recognized as potentiators of histamine poisoning. Accumulation of biogenic amines in fresh fish and fishery products has been mainly attributed to growth of bacteria possessing amino acid decarboxylase activity, which is facilitated by lack of hygienic conditions and strict temperature control during their storage. To this end, the effectiveness of traditional and modern approaches to control biogenic amine accumulation has been in the epicenter of intensive study. The aim of the present review article is to update and integrate current knowledge regarding the biogenic amine content of fresh fish and fishery products as well as the capacity of traditional and emerging control strategies.

IGS is abundant in polymorphism, which is widely used in the analysis of intraspecific genetic diversity and phylogenetic relationships among geographical populations. In this study, the 45S rDNA repeat unit of Saccharina japonica was obtained for the first time by BAC clone sequencing. The total length of the 45S rDNA repeat unit of S. japonica was 8 995 bp, including 5 420 bp of 18S-5.8S–25S rDNA, and 3 575 bp of IGS (Intergenic Spacer), with the GC content of 51.4 %. The IGS was composed of a 465 bp of 3â€⊃2;-outer transcribed spacer (ETS), an 874 bp 5â€⊃2;-ETS, and a 2 236 bp non-transcribed spacer (NTS), with the GC content of 50.1 %. Fiber-FISH (fiber-fluorescence in situ hybridization) analysis of the distribution of 45S rDNA repeat units on the bacterial artificial chromosome illustrated that each fiber had at least five continuously moniliform hybridization signal points. This study provided a new candidate molecular marker for detecting intraspecific polymorphisms of S. japonica. In addition, the successful fiber-FISH analysis of the 45S rDNA on BAC molecule would contribute to the construction of the physical map and map-based cloning of this kelp.

Responsible stock enhancement initiatives require baseline data of wild population demographic conditions that can be used in testing management outcomes. This study provides the first fishery-independent assessment of length- and age-based biological characteristics of exploited populations of Platycephalus fuscus in eastern Australia prior to stock enhancement. Sampling was conducted over seven estuaries spanning seven degrees of latitude and the geographical range of proposed stock enhancements. Populations in all estuaries showed evidence of length and age truncation, especially those subject to commercial fisheries where young individuals of both sexes dominated populations. Maximum longevities were 12 and 11 years for females and males respectively, but few females >5 years and males >3 years were generally sampled. Females dominated populations, and on average, the mean lengths and ages of females were greater than males within each estuary and across all age classes. Sexually dimorphic variation in growth was evident across all estuaries, with females attaining greater maximum lengths than males. Estuary-specific differences in individual growth were not identified. On average, over 50% of females sampled in each estuary were > the minimum legal length (MLL), but the opposite was evident for males. In contrast, over 25% of males in each estuary were > the mean length at maturity (L50), whereas in all but one estuary the L50. Stocked male and female P. fuscus should recruit to the fishery in 2 and 3 years, and contribute to the spawning stock in 1.5 and 4.5 years, respectively. This study provides important historical baseline data that can contribute to testing stock enhancement outcomes on populations.

In recirculating aquaculture systems, nitrification is usually accelerated by inoculating nitrifier or mature biocarriers. In this study, the performance of the establishment of nitrification in the MBBR according to three different strategies: conventional method (Control group A), inoculation with biofloc recovered from a tilapia biofloc culture system (Group B), and addition with extra nitrite (Group C) in the Moving bed biofilm reactor (MBBR) was compared. Among them, the biofloc-inoculated group considerably accelerated the nitrification process in the MBBR (38 d), which is roughly 18 d faster than the control group (A) (56 d) and 21 d faster than group C (59 d). Less ammonia (8 mg/L NH4+-N, 10 mg/L in other groups) and external nitrite (2 mg/L NO2−-N) in the influent caused effluent ammonia to drop more slowly (5 d slower than the control group, 8 d slower than the B group), which is detrimental to the nitrification process' development. Notably, the influent's hydraulic retention time (HRT) was reduced from 12 h to 6 h following the successful establishment of nitrification. During the adaptation to reduced HRT, the MBBR inoculated with biofloc experienced short-term changes in the water quality index of the effluent water, whereas the other groups did not. The biofilm seeded with biofloc had the highest mean gray value ratio (1.42) of live/dead cell fluorescence, which grew better and could cover the entire groove under multiple microscope observations. However, the other groups did not demonstrate a similar trend. In summary, the research found that seeding biofloc use as nitrification bioaugmentation into the MBBR of the recirculating aquaculture system (RAS) to greatly speed up the nitrification process.

In Amazonia, small-oriented family businesses or communities cultivate freshwater organisms as a source of income. Although effective management is fundamental for optimizing cultivated stocks, Amazonian aquaculture belittles the importance of genetic diversity, relying primarily on phenotypical characteristics during breeders’ selection. To provide a “proof of concept” built on the premise that implementing modern technologies is crucial to optimizing fish stocks in rural Amazonian fish farms, we conducted a pilot study assessing genetic diversity on cultivated Piaractus brachypomus from Caquetá, Colombia. We used mitochondrial control region (CR) sequences to evaluate heterogeneity. Our data revealed low genetic diversity and suggested that most sampled individuals probably originated from a single maternal lineage. Haplotype diversification resulted from discrete point mutations not associated with geographical location. Polymorphisms accumulate in non-conserved CR regions, yet the most divergent haplotypes display mutations in conserved CR sequences with roles in mitochondrial metabolisms and proliferation. Overall, our results indicate a need in the local industry to design breeding strategies to enhance diversity to avoid deleterious effects caused by inbreeding and domestication.

Genetic breeding is an important approach to improve the economic traits of aquaculture animals. Unfortunately, the genetic basis for important economic traits of red swamp crayfish, including growth-related traits, has not yet been reported. In the present study, two full-sib families and two natural populations were employed to identify quantitative trait loci (QTLs) for growth-related traits of red swamp crayfish. In total, 28 QTLs for five growth-related traits, including body weight, body length, carapace length, carapace width, and abdomen length, were repeatedly identified in more than two families/populations, by means of association analysis; nine of these displayed a heterosis effect. The phenotypic variations of the five investigated traits explained by the 28 QTLs ranged from 4.2% to 19.0%. Eight additive and three heterosis QTLs were further successfully validated using comparative analysis of favoured alleles between the small and big size crayfish groups in the natural population. In conclusion, this study investigated the genetic basis of growth-related traits in red swamp crayfish, which is of great significance for their application in the future molecular breeding of the species.

China's 13th Five-Year Plan elevated the national mandate for environmental sustainability. Chinese fisheries are characterized by full retention of high diversity catch harvested using unselective gears, creating ecological risks. Therefore, China launched pilot projects in management by Total Allowable Catch (TAC) in five coastal provinces in 2017 and 2018 to build experience with output controls. Fujian province launched an important pilot in its swimming crab fishery, the first to adopt a multispecies approach. To guide Fujian and other provinces in multispecies management, a workshop in April 2018 shared international experience. The workshop considered 13 case studies spanning a wide range of underlying scientific models and types of harvest controls. Multispecies harvest controls based on simple survey- or index-based models that aggregate trends for many species are typically operationally easier for managers and fishers. However, inadequate management can cause declines of individual species, sometimes leading to adoption of species-specific models and then species-specific harvest controls. This transition often incurs economic costs through scientific and management demands, and constraints on harvest of co-occurring species. The lessons revealed by the case studies suggest multispecies TACs might be effective in the Fujian swimming crab fishery given the modest number of species with similar and productive life history traits, and the market demand for all species. Continued experimentation with different management approaches through pilot projects can enable China to maintain progress toward sustainable fisheries goals under the 14th Five-Year Plan.

Using the multi-product dual revenue function framework, this paper examines the nature and extent of technical and economic interactions among five demersal species of Al-Batinah demersal fishery, Oman during the 2010–2016 period. The parameters of the system of output supply functions are estimated using Zellner's seemingly unrelated regressions (SUR) technique. The likelihood ratio test in relation to the structure of the multi-output production technology rejects the null-hypothesis of input-output separability and non-jointness in inputs. These results suggest that the underlying production technology is non-separable between the outputs and the quasi-fixed input, and the harvesting level of one species is likely to have spill-over economic effects on the harvesting levels of others. The own-price elasticities of output supply are found to be positive, inelastic, and statistically significant in four out of five cases suggesting that, other things being equal, fishers' supply decisions are influenced by the prevailing market prices of outputs. The estimated values of the cross-price elasticity of supply are negative, inelastic and statistically significant at the 5% level for eight output pairs. The calculated values of the Morishima elasticity of substitution (MES) indicate the presence of substitutability between ten output pairs. The cross-price elasticity estimates are in the range of −0.001 (between Emperor and Catfish) to −0.275 (between Seabream and Grouper) which is lower (in absolute value) than that of the MES estimates. The magnitudes of the cross-price elasticity and the MES estimates indicate the extent of spill-over effects of one species on the other and signal the extent of species targeting by fishers. A statistically significant spatial, seasonal, and inter-annual variability is observed in all species cases. Finally, the implications of the findings are discussed from the perspective of developing effective management approaches, achieving sustainability of fisheries resources and improving fishers' socio-economic conditions stipulated in the Five-Year development plans for the sector.

Changes in protein quality during ice storage affects the muscle structure, the textural quality, functional properties and the eating quality. Dynamic viscoelastic behaviour and gelling properties ofmeat proteinsin relation to histological changes in white leg shrimp muscles were assessed for 14 days in ice storage. Reduction in Ca2+ ATPase activity of fresh myofibrillar protein (MFP), fading of myosin banding pattern and increased gapping in myofibrils were clearly observed with progress of storage. The quality indices of the shrimp muscle were well correlated with histological and functional properties as a function of ice storage. Solubility of fresh MFP was 86.76% which decreased to 77.06% on the 14th day of storage period. Emulsion capacity found to increase during storage period. Gel strength of white leg shrimp meat was low (81 ± 14 g cm) and further, reduced nearly 60% compared to fresh sample at the end of storage. The considerable reductions (from 535.77 kPa to 246.56 kPa) in storage modulus values were evident of diminishing elasticity and gelling ability of the meat due to ice storage.Therefore, this study usherd that the histological deterioration in myofibrils may be used as an indication of diminishing biochemical quality and gelling behaviour of the proteins.

Crassostrea (Magallana) saidii has been commercially ranched in Malaysia and consumed for more than 160 years, but it was only recently identified as a new species to science. This study was conducted to evaluate the reproductive phenology of C. (M.) saidii. Samples of 30 individual oysters were taken monthly for 15 months from the sole population at Sungai Muar estuary in Johor, Malaysia. The sex ratio was 1:1.64 (male:female) for all examined specimens, with female numbers significantly higher. Hermaphrodism was detected in 1.56% of all samples. Spawning peaks in April (2019) and November (2018 and 2019), and were positively associated with the increased rainfall upstream. Gametogenesis occurred throughout the research period with temporal variations. The highest values of maturity index (MI) were recorded in March, August and October 2019, when most oysters were in matured and maturing stages. Condition index (CI) ranged from 31.90 ± 1.25 (April 2019) to 70.03 ± 3.23 (October 2019), exhibiting two peaks (March and October 2019) and subsequently reduced in CI indicating spawning consistency with histological observations. Anthropogenic stressors such as heavy sedimentation and inland development are threatening the survival of this species. The understanding of their reproductive biology is essential to ensure the survival and sustainability of C. (M.) saidii fishery.

The complete quantitative essential amino acid (EAA) requirements of aquacultured animals are largely unknown except for a handful of species. This is problematic because formulation of least-cost diets for target animals demands precise knowledge of EAA requirements. One way of approximating EAA requirements is to use correlations between whole-body and/or muscle EAA profiles using essential to total EAA ratios (A/E ratios). This method requires a reference, quantified EAA requirement, usually lysine (Lys). To systematically evaluate the A/E ratio method, muscle AA profiles were measured in 10 species of teleost and whiteleg shrimp. In fish, Lys represented the dominant muscle EAA measured, ranging between 7.06 and 9.58 g/100 g protein, whereas, in shrimp, arginine (Arg) was quantified as the principal EAA. For non-EAA, glutamate (Glu) and glutamine were consistently the NEAA recorded at highest levels whereas, in shrimp, Glu + Gln was highest followed by aspartate (Asp) plus asparagine (Asn). Except for Arg, which was twice that of fish (P 

Both in nature and in aquaculture, fish may experience periods of food scarcity or hunger. The metabolic regulation of fish when nutritional state changes is a complex process that involves many factors. To study glucose metabolism adaptability during fasting and re-feeding in the black carp (Mylopharyngodon piceus), we measured changes in some biochemical indicators related to glucose metabolism. Five fish were sampled on days 0, 1, 3, 5, and 10 of fasting (F, S1, S3, S5, and S10, respectively) and days 1, 3, and 5 of re-feeding (RF1, RF3, and RF5, respectively). The serum glucose concentration decreased significantly at S1, reached the lowest point at S10, and increased significantly at RF1 (P 

Management of fed-fish culture practices, at present, stands on two broad feed categories, (i) formulated proteinaceous aquafeeds and (ii) the natural resources. Judicious use of the later is gaining popularity since it offers sustainability to fish culture. Polyculture often targets phyto- and zooplanktonic resources, but mostly ignores periphyton. This review discusses the works on feed diversification performed independently at different times. Fishes, viz. Cyprinus carpio, Labeo rohita and Amblypharyngodon mola were projected as potential candidates for resource - nutrient management with feed diversification in rice fish culture. With C. carpio the rice fish culture called Aji Gnui Assonii in terrace water-logged rice field of Apatani Plateau, Arunachal Pradesh (India) is referred as self-substrating aquaculture practice. This monoculture practice experiences high carp productivity since there remains surplus of resources below the threshold level in these rice fields. Similarly, L. rohita, explores periphytic resources in ponds when substrates are installed. As a result, filter feeders get more foraging aquatic phase intensifying the resources for exploration in pond. This concept is suggested for rice fields with water depth above 50 cm where rice stems act as substrate. With trenches or refuge canals, resource intensification may be managed for more cultivable fishes in rice fields with

Hypoxia, a common environmental condition, can affect cell survival and physiological function by triggering oxidative stress. Akt/FoxO pathway has been proven to play a non-negligible role in the regulation of autophagy. However, the role of Akt/FoxO pathway in hypoxia-induced autophagy is unclear in fish. Therefore, in this study, grass carp hepatocyte cells (L8824) were treated by CoCl2 to simulate hypoxia, and the results showed that CoCl2 can increase the expression of Hif-1α protein at different concentrations or different treatment time. Further study found that hypoxia increased intracellular reactive oxygen species (ROS) level, and the expression of autophagy-related genes (LC3-II, pink1, beclin-1 and p62) and foxO1a/1b. The mitochondrial membrane potential (Δψm) was also depolarized, and autophagosomes were intriguingly detected by transmission electron microscope (TEM) after the treatment of hypoxia. Moreover, hypoxia inhibited Akt phosphorylation, while PI3K/Akt pathway inhibitor, LY294002 significantly up-regulated the expression of foxO1a/1b and autophagy-related genes. Additionally, silencing foxo1b also resulted in down-regulation of autophagy-related genes. It was demonstrated that hypoxia induced autophagy via Akt/FoxO1 pathway. These results will provide a new light on further understanding the role of Akt/FoxO pathway in the response to hypoxia in fish.

Numerical simulation is an important method for calculating the hydrodynamic performance of otter boards used in sea floor trawling. Although such simulations have been explored in prior studies, the effects of the proximity of the otter boards to the seafloor and the plume of upward-drawn sediment during bottom trawling have largely been ignored. In this study, we assessed these factors. The results show that within the angles of attack used during normal operations, the effect of the seafloor bottom boundary of the flow field on the hydrodynamic performance of an otter board is obvious. We found that when the ratio of the distance between the bottom of an otter board and the surface boundary of the flow field to the chord length of the board exceeds 0.4, the influence of the bottom boundary of the flow field on the hydrodynamic performance of the board is negligible. For values of less than 0.4, the seafloor bottom boundary has an increasingly obvious impact on the hydrodynamic performance as this ratio decreases. We also found that the turbid plume of ocean floor sediment raised during bottom trawling has an obvious effect on the lift and resistance coefficients of an otter board at high angles of attack. At low angles, this effect on the lift-to-drag ratio is reversed and less obvious. The simulation results show that the optimal lift-to-drag ratio decreases with an increase in the sediment concentration; however, beyond a certain threshold, an increasing concentration of sediments was not found to have an obvious impact on the lift-to-drag ratio.

The objective of this study was to evaluate the effect of modified atmosphere packaging (MAP) on fish skin, gills and intestines bacterial microbiome. Whole gilthead seabream was packed aerobically or under modified atmospheres (60% CO2, 30% N2, 10% O2) and stored isothermally at 0 °C. Next Generation Sequencing (NGS) analysis was applied for the characterization of fish microbiome on fish skin, gills, and intestines initially (time of packaging, 1 day after harvesting) and after 10 days of isothermal storage at 0 °C. NGS results indicated statistically significant differences in families’ richness and diversity in the tested fish tissues between aerobic and MAP packaging during storage at 0 °C. The most persistent bacteria were Proteobacteria for both packaging types. For fish skin microbiota, the initially prevailing families were Comamonadaceae, Enterobacteriaceae and Moraxellaceae while in the intestines Comamonadaceae, Anaplasmataceae, Bacillaceae and Enterobacteriaceae were the dominant bacteria. At the end of storage period, the fish microbiota was dominated by psychotropic and psychrophilic families (Pseudoalteromonadaceae, Psychromonadaceae, and Shewanellaceae), while families such as Comamonadaceae were persistent under MAP conditions. By 8 days of fish storage at 0 °C, ΜΑΡ samples exhibited higher sensory scorings than the respective aerobically stored fish, indicating better retention of fish freshness and fish quality attributes under MAP. Based on the results of the study, MAP modified significantly the microbiological status and extended the shelf life of fish. NGS was a powerful tool that provided a more complete assessment compared to a culture-based analysis.

In order to develop a method that apply sampling survey data randomly obtained at fishing ports to fish stock assessments, based on fish landing surveys conducted at fishing ports in the northern South China Sea (SCS), 19 Threadfin porgy (Evynnis cardinalis) catch per unit effort (CPUE) datasets were collected for fishing vessels with different gear types and engine powers and incorporated into surplus production models. Considering only the fitting performance, the Schaefer model had the best overall goodness of fit, followed by the Fox, CYP, W–H, and Schnute models. Among fishing vessels with different gears and engine powers, the data were best fitted for single-trawl vessels powered by 301–400-kW engines and for gillnet vessels powered by > 200-kW engines. Eight model expressions were superior and selected for subsequent analyses based on their goodness of fit and relative residuals. The Kobe plot analysis results showed an optimistic fish stock status when using the four model expressions, required more caution when using three model expressions and output pessimistic estimations using one model expression. Considering the incomplete information acquired, a compromising decision-making method was used to derive a 2017 northern SCS E. cardinalis total allowed catch (TAC) of 44,691.21 t. The different conclusions drawn from estimations using CPUEs reflect variable exploitation and utilization fish stock statuses among fishing vessels with different gears and engine powers. Hence, the fishing operations were grouped according to their CPUE relationship, and recommendations regarding optimum fishing efforts were assigned to the groups following a fundamental principle: to improve fishery TAC management, fishing efforts should be reduced if the fish stock assessment is pessimistic and maintained if the assessment is optimistic. This study providing a feasible technical method for the TAC management of China's offshore fisheries.

Melanization of shrimp gills is a general symptom in shrimp black bill diseases (sBG); therefore, the cause is not immediately apparent. This study aimed to determine the primary and secondary agents associated with a black gill outbreak in the Delvar complex in the Bushehr Province of Iran. During July and August of 2020, 450 healthy and affected shrimps were collected based on brown to black gill color from three farms of the Bushehr Province in Iran. Characterization of pathogens was performed by gross signs, wet mounts, microbiological tests, histopathology methods, and sequencing of molecular markers. The mean weight and length of infected shrimps was significantly (P 

International soft law is not legally binding, but nevertheless it embodies mainstream values and influences the formation of hard law in global governance. Marine fisheries have become important arenas of global governance, in which developing states are crucial participants. The interactions between soft law and hard law in global marine fisheries can be mainly summarized as follows: soft law can be the precursor for hard law and be implicitly introduced into hard law to enhance normativity; hard law can also be incorporated into soft law. This paper explores the IUU fishing case to illustrate the significant role of soft law on international fisheries law and identify gaps in global marine fisheries governance. The development of international instruments to combat IUU fishing within FAO undergoes a process from voluntary to legally binding with the engagement and promotion of some developed states for their benefits. But IUU fishing concept is defective in its drafting as well as in practical application and indicates the value of emphasizing conservation over economic and social development, which is contrary to the principle of sustainable development and fails to meet the requirements of the developing states. The paper suggests to fill this gap by converting existing values in soft law to foster fishing rules that benefit all states and provide some insights towards this direction.

The study investigated the genetic variation of Parachanna obscura from five rivers (Anambra, Ibbi, Imo, Katsina-Ala and Ogun) in Nigeria using the mitochondrial cytochrome oxidase 1 gene. DNA was extracted from 19, 22, 16, 18 and 21 fin clips per river population, respectively and subjected to polymerase chain reaction. A total of 96 sequences, each with 671 bp were obtained with 38 (5.6%) polymorphic, 27 (3.8%) parsimoniously informative and 659 (98.2%) conserved sites. Mean nucleotide composition was C = 28.07%, T = 29.43%, A = 22.18%, G = 20.32%. A total of 40 haplotypes with 38 unique sequences as well as 24 substitutions with 22 transversions and two transitions were obtained. Nucleotide diversity among populations ranged from 0.00184 to 0.00888 representing Ibbi and Imo, respectively while haplotype diversity ranged from 0.77056 to 0.95000 also, from Ibbi and Imo, respectively. Analyses of molecular variance showed that the intra-population variation accounted for 50.05%. Topology from phylogenetic analyses revealed that P. obscura from Imo River was distinctly different from the rest.

In this paper, we studied the structure, expression and function of black carp insulin gene. The complete Mylopharyngodon piceus insulin (Mp-Ins) gene is 1,965 bp long and includes a 1,499 bp 5Ê⊃1;-untranslated region (UTR), a 139 bp 3â€⊃2;-UTR with a poly(A) tail, and an open reading frame (ORF) of 327 bp. The predicted molecular weight of the recombinant Mp-Ins(rMp-Ins) protein is 11.87 kDa. The mRNA expression of Mp-Ins is upregulated in the brain and liver. After the injection of rMp-Ins, Mp-Ins mRNA transcript abundance was significantly upregulated in the liver. The rMp-Ins protein could inhibit the concentration of glycogen phosphorylase (GP), growth hormone (GH), fatty acid synthase (FAS), and insulin-like growth factors-1 (IGF-1), and it also significantly increased the concentration of PI3K. Additionally, the injection of rMp-Ins did not have a significant impact on the glucose-6-phosphatase (G6Pase) content in blood. In situ hybridization results showed that the positive signal of the Mp-Ins gene was mainly concentrated in the cell nucleus of brain tissue and the cell membrane of liver tissue and muscle tissue. Together, these results demonstrated that Mp-Ins plays an important role in growth and metabolism in M. piceus.

Major histocompatibility complex (MHC) molecules play a critical role in the immune response of vertebrate animals by presenting foreign antigens to T lymphocytes. In this study, we first cloned and identified a classical and a novel nonclassical MHC I α molecules from Japanese eel (Anguilla japonica), named as AjMHC I-UBA and AjMHC I-L, respectively. The full-length cDNA of AjMHC I-UBA contains an open reading frame (ORF) of 1047 bp encoding a predicted protein of 348 amino acids, while AjMHC I-L 1089 bp encodes 362 amino acids. The multiple alignment of the amino acid sequence showed that AjMHC I-UBA and AjMHC I-L consist of an N-terminal MHC I superfamily domain within α1 and α2 helices, an IgC-MHC I α3 domain, and a transmembrane region close to the C-terminal, which are similar to other fish and mammal species. Molecular polymorphism analysis showed that eight different major alleles of AjMHC I-UBA, named as AjMHC I-UBA*0101～1001, were identified from six Japanese eel individuals. Furthermore, a distinguishing signature of the nonclassical L-lineage genes specific motif “HINMTL”, including an N-glycosylation site (NXS/T), was present in the α3 domain of AjMHC I-L sequences. Although the predicted three-dimensional structures of AjMHC I-UBA and AjMHC I-L are similar to that of human MHC I α, phylogenetic analysis showed that these two protein molecules belong to classical MHC I UBA gene of U-lineage and nonclassical MHC I gene of L-lineage, respectively. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the highest expression of AjMHC I-UBA and AjMHC I-L was found in the intestine and the expression level of AjMHC I-UBA in all of the examined tissues was significantly higher than that of AjMHC I-L. The expressions of AjMHC I-UBA and AjMHC I-L in liver, kidney and spleen were significantly induced following injection with the viral mimic poly I:C, LPS, and Aeromonas hydrophila infection. In vitro, the AjMHC I-UBA and AjMHC I-L transcripts of Japanese eel liver cells were significantly enhanced by the treatment of poly I:C or the stimulation of the high concentration of A. hydrophila. Subcellular localization showed that under natural conditions, AjMHC I-UBA and AjMHC I-L were uniformly distributed in the cytoplasm, and aggregated into spots or flakes in the cytoplasm after the stimulation of poly I:C or LPS. These results collectively suggested that AjMHC I-UBA and AjMHC I-L are important components possibly involved in Japanese eel defense against viral and bacterial infection. Taken together, these findings provide valuable insight into the immune function of MHC class I in the immune system of teleost.

To stop the decline of swimming crab (Portunus trituberculatus) stocks in the East China Sea, escape vents on crab pots are urgently required to improve pot selectivity and enable release of sublegal-sized crabs. This study presents field comparative fishing experiments, which examined the effectiveness of different shapes and sizes of escape vents in crab pots for the release of swimming crabs. Two sizes each of rectangular, elliptic, and circular escape vents were tested. The results of comparative fishing experiments indicated that experimental pots with escape vents, regardless of their configuration, caught significantly fewer sublegal-sized crabs (

Transport in water is the most common method for transporting live fish in China, however, transport is a strong stressor. Transport stress could lead to a reduced immune and antioxidant system function of tiger grouper, resulting in sickness and death. Besides, tiger grouper were continuously stressed during transport, which resulted in quality deterioration. It is necessary that find a way to relieve the stress of transportation of tiger grouper. Ascorbic acid is not only a good anti-stress agent, but it is also an effective immunostimulant. Î⊃2;-1,3-glucan is a feed additive that can enhance the immune response of fish. Therefore, this study evaluated the effects of Î⊃2;-1,3-glucan and ascorbic acid on the nutritional-immune response and antioxidant signaling pathways of live tiger grouper during simulated transport. Results indicated that adding Î⊃2;-1,3-glucan and ascorbic acid in transport-water muted the increase of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. In addition, Î⊃2;-1,3-glucan and ascorbic acid activated Nrf2 and mediated TOR expression and then up-regulate related mRNA expression of antioxidant and immune enzymes. We concluded that the application of Î⊃2;-1,3-glucan and ascorbic acid inhibit the increase of metabolism enzymes and inflammatory factors and activate immune and antioxidant signaling pathways to relieve oxidant stress, immune response, and apoptosis. Reducing the loss of amino acids provided nutrients to relieve oxidative stress and immune response, which demonstrated immune-nutritional response in live tiger grouper during simulated transport. These results may provide a new solution for alleviating the decline of immune and antioxidant function of tiger grouper caused by transportation stress.

Microfungi have been explored further as supplement constituents in shrimp culture due to their rich protein, lipid, essential amino acids, fatty acids, and various bioactive compounds. The researchers have evaluated the effects of two microfungi powders (Mucor circinelloides and Trichoderma harzianum) as feed supplements on growth performance, bacterial communities, and the biomass nutritional profile of white shrimp (Litopenaeus vannamei). The results showed that commercial/artificial feed (Feng-Li) with supplementation microfungi powder had a different effect on white shrimp growth performance than control after 62 days of the grow-out period. Supplementation with 1.5% M. circinelloides powder (M-2) could improve the growth performance of white shrimp, especially the survival rate (81.33%), final body weight (5.21 g), and shrimp biomass (211.35 g). In contrast, supplementation with 1.5% T. harzianum powder (T-2) did not improve the growth performance of white shrimp compared to control (p > 0.05). Furthermore, it also affected the profile of the bacterial community in culture water as well as in shrimp intestines. Supplementation with both microfungi could reduce the total number of bacteria in culture water at the end of the experiment, where the lowest number was obtained in treatment T-2 (3.9 × 10 5 CFU/mL), followed by M-2 (9.9 × 10 5 CFU/mL) and control (4.4 × 10 6 CFU/mL). In the culture water, 20 isolates of culturable bacteria were found during the trial, with the dominant bacteria in M-2: Bacillus cereus, Bacillus velezensis, Gordonia polyisoprenivorans, T-2: Acinetobacter sp., Gordonia polyisoprenivorans, Micrococcus luteus. Based on average well colour development (AWCD), the highest bacterial activity was in the M-2 (0.297–0.707), followed by T-2 (0.226–0.717) and control (0.094–0.694). The highest substrate group utilised in M-2 and T-2 were polymers (0.896 and 1.348) and control: amines (0.100). The highest Shannon diversity index was obtained in the M-2 (2.508), followed by control (2.286) and the T-2 (2.157). As many as 11 isolates of culturable bacteria were found in the shrimp intestine, with dominant bacteria in M-2: Bacillus velezensis, Micrococcus luteus, Bacillus cereus, T-2: Bacillus velezensis, Micrococcus sp.2, Demequina activiva. The highest bacterial activity was in M-2 (2.259), followed by control (2.020) and T-2 (0.050). The highest substrate group utilisation was in M-2: polymers (2.564), T-2: carbohydrates (0.094), and control: polymers (2.185). The highest Shannon diversity index was in the M-2 (3.234), followed by control (3.230) and the T-2 (0.751). In addition, 1.5% M. circinelloides and T. harzianum supplementation increased white shrimp muscle protein content up to 79.21% and 80.40%, respectively, compared to control (76.73%). In conclusion, using Mucor circinelloides powder as a feed supplement can improve the growth performance of white shrimp, increase the functional/probiotic bacteria: B. cereus and B. velezensis in cultur and shrimp's intestine, and increase the protein content in shrimp muscle tissue. However, more in-depth research is needed, especially on anti-nutritional compounds from fungi that affect shrimp growth.

The aim of this study was to record demersal species from lagoon in Luang Island, a small and remote island in Maluku, Indonesia. Quantitative and qualitative methods were employed with the assistance of the local fishers using 4 different methods of fishing: gillnets, spear guns, traps, and handlines. Fisher knowledge informed fish abundance and frequency of occurrence. A total of 348 individual fish distributed across 53 species were recorded from the catch of 4 gear types. Bray-Curtis similarity scores of fish assemblages at different habitats was ranged from 7.19% to 10.35%. The nMDS bi-plot visualized a distinct dimension with which to allocate 3 habitats separately from the sand-seagrass habitat. Significant similarity of species at 4 different habitats (ANOSIM R2 = 0.124, P = 0.002) suggested that the habitat parameter was not able to predict different communities of fish. This paper is the first contribution on the composition of lagoon ichthyofaunal in Southwest Maluku Regency. Wise attitude towards marine resource exploitation such as traditional conservation, less fishing pressure and marine culture will maintain the healthy ichthyofaunal assemblages in a tropical lagoon ecosystem.

Aquaculture industry contributes significant aquaculture species production to meet fish protein demand from the world. The industry is gearing towards intensification to increase more production in the near future. Various technologies and efforts were introduced into aquaculture industry to bring it up to the next higher level. However, the development of aquaculture industry is hindered by disease constraint. As a result, excessive use of antibiotics and chemicals were applied to reduce or minimize risk of disease outbreak in aquaculture farming activity. Subsequently, aquacultures products and environment were highly exposed to these antibiotics and chemicals. To resolve this issue, fish farmers were encouraged to utilize alternative method in aquaculture species health management. Prebiotics has become a new approach in aquaculture industry to maintain aquaculture species health and a good environment at the same time produce chemical and antibiotic-free aquaculture product. In this review paper, we summarize and discuss the effects of prebiotic mixtures administration on growth performance, immune response, disease resistance, and tolerance against abiotic stressors of aquatic animals.

Impairment of fish growth and immune system due to stress and disease are major constraints in aquaculture industry. Traditionally, antibiotic was used as prophylactic agent in the health management of aquaculture species. However, antibiotic only provide a temporary solution to the problem of disease outbreak. Over-reliance on antibiotic also has led to the increasing cases of antibiotic resistance among pathogenic bacteria from aquaculture sites and contamination of antibiotic residues into human food chain. Probiotic, prebiotic and symbiotic are therefore suggested as alternatives to prophylactic antibiotic to be used in the aquaculture industry. A potential prophylactic agent is polysaccharide that could be developed into an alternative antibiotic for aquatic animals. In this review paper, definition, sources, and mode of action of polysaccharide are presented. The roles of polysaccharides in fish farming with emphasis on growth improvement, immune system enhancement, disease resistance stimulation in tilapia farming, and the effects of polysaccharides on abiotic stressors are summarized and discussed.

In this study, we investigated the impact of water temperature on pearl formation and the molecular mechanisms underlying this biomineralization process in the mussel Hyriopsis cumingii. In the laboratory experiment, recipient mussels received saibo grafts from donor mussels and then were cultivated at five temperatures (16, 20, 24, 28, and 32 °C) for 1 month. We found that speed of pearl formation varied with water temperature: there was no visible pearl granules at 16 and 20 °C, tawny pearl granules were collected at 24 °C and lustrous pearl granules were collected at 28 and 32 °C. The expressions of several nacreous layer matrix protein genes (hic22, hic24, HcTyr Hc-upsalin and Hcperlucin) at 28 °C and 32 °C were peaked on day 28, and the expressions of other nacreous layer matrix protein genes (hic52 and hic74) on day 28 were significant higher than day 14. In the natural environment, pearl deposition rate also increased as water temperature rose, and the optimum range for pearl growth in H. cumingii was between 28.3 and 30.3 °C. Expression of the prismatic layer-related matrix protein genes hic31 and both prismatic and nacreous layer-related matrix protein gene silkmapin was significantly high in winter, and expressions of the nacreous layer-related matrix protein genes (hic24, hic74, HcTyr, Hc-upsalin and Hcperlucin) were always higher during higher temperature seasons compared with winter. These results indicate that high water temperature can speed up pearl formation and further regulate matrix protein secretion to accelerate pearl nacre deposition.

We estimated the proportion of hatchery and natural fall spawning chum salmon returning to the Amur River using chemical markers specific to hatchery-origin fry. We used otolith microchemistry technique to identify fish with artificial origin among returning spawners. First, we found that juveniles of artificial origin had higher values of the Sr:Ca molar ratio of the otoliths’ edge zone compared with juveniles of natural origin, what can be related to the use of rearing feed produced from raw materials of marine origin rich in strontium. Then we observed that most of the spawners from Anyuisky Hatchery and from the Amur River mouth at the start of the spawning migration has also the higher value of Sr:Ca molar ratio of the juvenile zone of otoliths. Also, adults with higher values of the Sr:Ca molar ratio are characterized by a skewed right in the peak of the age distribution. Both, the age structure and phenological shift in the time of spawning migration of individuals with higher value of the used chemical marker corresponds to results of studies on hatchery-produced chum salmon completed at different parts on Northern Pacific. The results of this study will be used in the management of Amur fall chum salmon fisheries, and also demonstrates the necessity of the development of specific measures for increasing the survival of juvenile anadromous salmonids released at large rivers and exposed to prolonged freshwater migration to the ocean. As a further application of the methodology, we plan to identify the markers specific to each of the hatcheries and main spawning tributaries belonging to Amur River catchments. This will be an important step in the evaluation of the contribution of different stocks in mixed fisheries and also in the estimation of the effect of hatchery releases on naturally spawning stocks of Amur fall chum. Following to, our results may indicate the applicability of this approach for the determination of artificial-origin fish in a mixed sample of the Amur fall chum salmon.

There has been an increasing emphasis on reducing the environmental impacts of penaeid trawls by modifying their anterior sections. In one Australian estuary, this approach has culminated in a new generic trawl comprising a slightly smaller mesh size, and steeper and shorter side panels than traditional trawls, combined with a top panel extending forwards of the bottom panel (termed ‘lead-ahead’) and no headline floats. This study sought to investigate if an additional simple, cumulative modification (tickler chain) might help promote adoption of the new trawl, via improved penaeid catches. Six volunteer fishers towing pairs of either the traditional or new trawls in double rigs were asked if an observer could accompany fishing trips, and alternately attach a light tickler chain (∼3 kg) anterior to the ground gear of one trawl. Regardless of the trawl design, the tickler chains significantly increased the catch weights of penaeids, but relatively more so in the new trawls (by 1.11 × vs 1.08 × ). The tickler chains also significantly increased the number and weight of total bycatch in the traditional trawls (by up to 1.22 × ), but not in the new trawls—although there were variable species-specific effects. In terms of total effects, the data support using tickler chains to increase the efficiency of the new trawls and their cumulative benefits, and could be promoted to facilitate broader inter- and intra-fleet adoption.

Insects, particularly black soldier fly larvae (BSFM), Hermetia illucens, have been regarded as promising protein and lipid sources in animal feed, including fish. Digestibility is the key factor that affects nutrient utilization, feeding physiology and efficiency. In the present work, the effect of BSFM on the digestibility of red hybrid tilapia (RHT) compared to fish meal (FM) was ultimately unveiled. A 56-day growth trial was performed with 60 RHT (∼30 g) randomly distributed into six tanks and fed two experimental diets containing FM as a reference diet and BSFM as a test diet. In addition, faeces were collected to determine their chromium concentration and proximate composition. The apparent digestibility coefficient (ADC) of dry matter, crude protein and energy in the BSFM diet were observed to be significantly higher than those in the FM diet. Besides, the growth performance of fish fed with the BSFM diet exhibited significantly higher (P