Aquaculture Management Research Articles

Internet of Things- Based Automatic Feeder and Monitoring of Water Temperature, PH, and Salinity for Litopenaeus Vannamei Shrimp

Aquaculture of Litopenaeus Vannamei shrimp is one of Indonesia's most crucial commodity export shrimp. Aquaculture feed management and environmental management are essential factors in determining shrimp sustainability. To maximize shrimp farming results, proper feeding, water quality control, and con-tinuous monitoring of three critical parameters: temperature, power of hydrogen (pH), and salinity levels in ponds are required. This study aims to feed the shrimp automatically at predetermined times (07.00, 11.00, 16.00 and 20.00). At the same time, it will monitor pond water quality parameters. Temperature, pH and salinity are all factors monitored. Every 10 minutes, monitored data is stored in ThingSpeak using IoT technology. The design goal has a specific threshold to avoid future problems. A Telegram notification is sent every 10 seconds when the water condition exceeds the threshold. The overall accuracy rate of 98.81%, pH of 96.6%, and salinity of 99.17% demonstrate that the system works correctly.

Application of probiotics for sustainable and environment-friendly aquaculture management - A review

Application of probiotics for sustainable and environment-friendly aquaculture management - A review

Hypothermia-mediated oxidative stress induces immunosuppression, morphological impairment and cell fate disorder in the intestine of freshwater drum, Aplodinotus grunniens

The mechanism of the intestine in freshwater drum response to hypothermia exposure has not been investigated, despite the fact that it is a key organ of metabolism and immunity. Here, we conducted an 8-day hypothermia experiment under 10 °C to uncover the underlying mechanism in the intestine of freshwater drum. Morphologically, hypothermia exposure caused intestinal microvilli shortening, mitochondrial structure disruption, and tight junction damage. Physiologically, immunosuppression and inflammatory response were involved in the intestinal hypothermia response. According to transcriptome analysis, we discovered that hypothermia exposure induced apoptosis and ferroptosis in the intestine. Combined with correlation analyses, oxidative stress was considered critical in modifying the intestinal hypothermia response. In conclusion, hypothermia-induced oxidative stress leads to intestinal structure damage, immunosuppression and cell fate alterations, ultimately affecting the well-being of freshwater drum. This may provide some insights into hypothermia prevention in aquaculture management.

GENETIC DIVERSITY AND POPULATION STRUCTURE OF THE EUROPEAN EEL (ANGUILLA ANGUILLA) IN BALTIC LAKELAND

Anguilla anguilla (Linnaeus, 1758) is the unique catadromous fish species in the Latvian fauna. The Baltic Lakeland area representing naturally recruited and introduced eels. In recent decades, its population has decreased not only in Latvia, but also in Europe. European eel critically endangered due to overfishing of glass eels, blocking of migratory paths, deaths in HPS turbines, water pollution and diseases and parasites. Only some bodies of water are freely accessible to natural migration of eels in Latvia.Currently, its position has been recognized as being critical, and a range of normative acts have been adopted for its restoration, such as the Regulation EC 1100/2007. The restocking programs of the European eel Anguilla anguilla have been conducted for nearly one century in Latvia.This study provides the first data on population structure of freshwater eels in Baltic Lakeland, for use in eel conservation and management of aquaculture on a regional and/or global scale. By analysing the sequences of the Cyt b gene of mtDNA for individuals caught in locations throughout in Baltic Lakeland, we determined the population genetic structure of A. anguilla in the area. The diversity of haplotypes was studied in ten waterbodies from part of Baltic Lakeland, namely Lake Sīvers, Lake Usmas, Lake Ķišezers, Lake Liepājas, Lake Alūksnes, Lake Rāznas, Lake Vialikija Švakšty, Lake Svir, Lake Myadzyel, Myadzelka river. Additionally, this study investigated the affinity of the Latvian populations to other A. anguilla populations around the world.This is the first report about eel’s population genetic diversity in Baltic Lakeland. Haplotype variation was different in all investigated waterbodies. In current studies seven new unique haplotypes were detected. Eel population in Baltic Lakeland shows quite high genetic diversity and rapid population expansions, which possibly is results of intensive restocking program. Sequences characterized Anguilla rostrata in Lake Alūksnes were detected.

Autophagy increases the survival rate of Macrobrachium rosenbergiiin after Aeromonas hydrophila infection

Autophagy is known as crucial components of crustacean innate immunity against pathogens. The dynamic changes of autophagy level during infectious disease is apparently related to disease severity, which needs to deeply understand for a health development and management of aquaculture. In this study, the role of autophagy during A. hydrophila infection was elucidated in M. rosenbergii. Adult freshwater prawn was firstly administered A. hydrophila to assess the virulence of the isolated strain. Pathological analysis of hepatopancreas and intestine tissues of moribund prawn showed significantly pathological changes, including cellular swelling and vacuolation, contraction or karyorrhexis of nuclei, dissolution and necrosis of villi, structural destruction of the striate border. A significant apoptosis and autophagy was observed in hepatopancreas tissues of the infected shrimp. Moreover, the rapamycin-pretreated groups showed high survival rate in contrast with drastic high mortality in autophagy-suppressed groups. Further analysis showed that the elevated autophagy levels restricted apoptosis signals. We conclude that autophagy plays a positive role during A. hydrophila infection and may be is a new therapeutic target for bacterial disease.

Characterization of the productive articulation and tourism in the aquaculture farms of Toluca, State of Mexico, and Lake Tota in Boyacá, Colombia, first advance

Global aquaculture has had exponential growth in recent decades (FAO,2020), mainly due to the decrease of wild fish populations in the global oceans and inland water bodies. That is why, according to the projection of specialists, by 2050 these species will have to be produced in controlled conditions, creating, improving, and developing farms that favor the consumption of this food locally, nationally, and internationally. For this reason, the productive articulation that is carried out between the different actors, Company, government, university, and associations of producers, (quadruple hélix), favors the interrelation between them, thus achieving social and economic benefits for the participants. Specifically, this research Project within the framework of the Pacific Alliance Treat aims to analyze the trout farms in Toluca, State of México, and the Tota lagoon in Boyacá, Colombia, to determine in a first approach the characterization of these groups and their relationship with tourism, to propose alternatives that promote greater involvement of the participants and increase collective benefits. This field research, which is carried out in the aforementioned localities, with a qualitative, non-experimental approach based on content analysis, collecting existing data in statistics and official documents of both countries, and with structured interviews conducted with aquaculture managers of the federal and local government and owners of aquaculture farms. The article is preliminary to know the operating conditions of the farms, and the link with Tourism, which will be linked to subsequent publications once the process of obtaining the actors of the productive groupings in México and Colombia is concluded.

Generalised deep learning model for semi-automated length measurement of fish in stereo-BRUVS

Assessing the health of fish populations relies on determining the length of fish in sample species subsets, in conjunction with other key ecosystem markers; thereby, inferring overall health of communities. Despite attempts to use artificial intelligence (AI) to measure fish, most measurement remains a manual process, often necessitating fish being removed from the water. Overcoming this limitation and potentially harmful intervention by measuring fish without disturbance in their natural habitat would greatly enhance and expedite the process. Stereo baited remote underwater video systems (stereo-BRUVS) are widely used as a non-invasive, stressless method for manually counting and measuring fish in aquaculture, fisheries and conservation management. However, the application of deep learning (DL) to stereo-BRUVS image processing is showing encouraging progress towards replacing the manual and labour-intensive task of precisely locating the heads and tails of fish with computer-vision-based algorithms. Here, we present a generalised, semi-automated method for measuring the length of fish using DL with near-human accuracy for numerous species of fish. Additionally, we combine the DL method with a highly precise stereo-BRUVS calibration method, which uses calibration cubes to ensure precision within a few millimetres in calculated lengths. In a human versus DL comparison of accuracy, we show that, although DL commonly slightly over-estimates or under-estimates length, with enough repeated measurements, the two values average and converge to the same length, demonstrated by a Pearson correlation coefficient (r) of 0.99 for n=3954 measurement in ‘out-of-sample’ test data. We demonstrate, through the inclusion of visual examples of stereo-BRUVS scenes, the accuracy of this approach. The head-to-tail measurement method presented here builds on, and advances, previously published object detection for stereo-BRUVS. Furthermore, by replacing the manual process of four careful mouse clicks on the screen to precisely locate the head and tail of a fish in two images, with two fast clicks anywhere on that fish in those two images, a significant reduction in image processing and analysis time is expected. By reducing analysis times, more images can be processed; thereby, increasing the amount of data available for environmental reporting and decision making.

A detailed look at the impacts of biofloc on immunological and hematological parameters and improving resistance to diseases

The innate immunity of invertebrates serves as a critical trait that provides a valuable foundation for studying the common biological responses to environmental changes. With the exponential growth of the human population, the demand for protein has soared, leading to the intensification of aquaculture. Regrettably, this intensification has resulted in the overuse of antibiotics and chemotherapeutics, which have led to the emergence of resistant microbes or superbugs. In this regard, biofloc technology (BFT) emerges as a promising strategy for disease management in aquaculture. By harnessing the power of antibiotics, probiotics, and prebiotics, BFT offers a sustainable and eco-friendly approach that can help mitigate the negative impacts of harmful chemicals. By adopting this innovative technology, we can enhance the immunity and promote the health of aquatic organisms, thereby ensuring the long-term viability of the aquaculture industry. Using a proper carbon to nitrogen ratio, normally adding an external carbon source, BFT recycles waste in culture system with no water exchange. Heterotrophic bacteria grow along with other key microbes in the culture water. Heterotrophs play a major role in assimilating ammonia from feed and fecal waste, crucial pathway to form suspended microbial aggregates (known as 'biofloc'); while chemoautotrophs (e.g. nitrifying bacteria) oxidize ammonia into nitrite, and nitrite into nitrate promoting a healthy farming conditions. By using a highly aerated media and an organic substrates that contain carbon and nitrogen, protein-rich microbes are able to flocculate in culture water. Several types of microorganisms and their cell components have been studied and applied to aquatic animals as probiotics or immunostimulants (lipopolysaccharide, peptidoglycan, and 1-glucans) to enhance their innate immunity and antioxidant status, thereby enhancing their resistance to disease. In recent years, many studies have been conducted on the application of BFT for different farmed aquatic species and it has been observed as a promising method for the development of sustainable aquaculture, especially due to less use of water, increased productivity and biosecurity, but also an enhancement of the health status of several aquaculture species. This review analyses the immune status, antioxidant activity, blood and biochemical parameters, and level of resistance against pathogenic agents of aquatic animals farmed in BFT systems. This manuscript aims to gather and showcase the scientific evidences related to biofloc as a 'health promoter' in a unique document for the industry and academia.

Evaluation of long-term cryostorage on sperm function and fertility of brown-marbled grouper (Epinephelus fuscoguttatus)

Cryopreservation of fish semen is a valuable technique for reproductive management in aquaculture. The aim of this study was to evaluate the effect of long-term storage in liquid nitrogen on post-thaw sperm functional parameters of brown-marbled grouper (Epinephelus fuscoguttatus). Samples were cryopreserved in a simple freezing medium (10 % DMSO + 0.3 M Glucose), sperm quality parameters were assessed at different storage periods (one month, one year, 2 years and 3 years). Our results indicated that cryostorage periods had a significant effect on the quality of frozen-thawed spermatozoa. Compared with fresh semen, cryopreserved sample was characterized by an overall decline in motility, viability, mitochondrial membrane potential (MMP), ATP content and increased level of lipid peroxidation with the storage time going on. For the analyzed quality parameters, there were no significant differences in storage time cryopreserved over one month. After 3 years of storage, frozen sperm still showed relatively high total motility, viability and MMP (all over 80 %), yielding acceptable fertilizing capacity close to that of fresh sperm. Therefore, it can be concluded that brown-marbled grouper sperm could be effectively cryopreserved for at least 3 years. The results of this study would be helpful to optimize gamete management in routine hatchery practices.

Genetic Diversity of Asian Seabass (Lates calcarifer) in Captive Populations

This study examined the genetic diversity of Asian seabass (Lates calcarifer) captive populations using sequencing of the mitochondrial DNA cytochrome c oxidase I (COI) fragment. The phylogenetic analyses of the 609 base pair regions of the COI fragment from 146 samples identified 15 haplotypes and divided them into two clades with a genetic divergence of 10%. Thus, phylogenetic results supported two genetic groups (the Australia/Southeast Asia group and the India/Myanmar group) within the captive populations under study. Mixed levels of genetic diversity were observed among captive populations, which indicated a certain degree of inbreeding depression. The findings would be useful for future aquaculture management of captive Asian seabass in Malaysia.

Long-term hypoxia stress-induced oxidative stress, cell apoptosis, and immune response in the intestine of Pelteobagrus vachelli.

Hypoxia is a common phenomenon in aquaculture. With the dissolved oxygen (DO) 3.75 ± 0.25mg O2 /L for hypoxia group and 7.25 ± 0.25mg O2 /L for control group for 30, 60, and 90days, long-term hypoxia stress was used to investigate the oxidative stress, apoptosis, and immunity in the intestine of Pelteobagrus vachelli. According to the results of measurement of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and catalase (CAT) activities and malondialdehyde (MDA) content, the oxidative stress ability of the intestine was activated at 30days and impaired at 60 and 90days. The upregulation of Bcl-2-associated x (Bax); downregulation of B cell lymphoma-2 (Bcl-2); increased activities of caspase-3, caspase-9, and Na+-K+-ATPase; decreased activities of succinate dehydrogenase (SDH); and the release of cytochrome c (Cyt-c) in mitochondria revealed that hypoxia induced the apoptosis. Moreover, heat shock protein 70 (HSP 70), heat shock protein 90 (HSP 90), immunoglobulin M (IgM), and C-lysozyme (C-LZM) were activated to inhibit apoptosis, but the immunoregulatory function might be damaged at 60 and 90days. This study provides a theoretical foundation for understanding the mechanisms of hypoxia stress and aquaculture management of P. vachelli.

Rapid Detection of DNA and RNA Shrimp Viruses Using CRISPR-Based Diagnostics.

Timely detection of persistent and emerging pathogens is critical to controlling disease spread, particularly in high-density populations with increased contact between individuals and limited-to-no ability to quarantine. Standard molecular diagnostic tests for surveying pathogenic microbes have provided the sensitivity needed for early detection, but lag in time-to-result leading to delayed action. On-site diagnostics alleviate this lag, but current technologies are less sensitive and adaptable than lab-based molecular methods. Towards the development of improved on-site diagnostics, we demonstrated the adaptability of a loop-mediated isothermal amplification-CRISPR coupled technology for detecting DNA and RNA viruses that have greatly impacted shrimp populations worldwide; White Spot Syndrome Virus and Taura Syndrome Virus. Both CRISPR-based fluorescent assays we developed showed similar sensitivity and accuracy for viral detection and load quantification to real-time PCR. Additionally, both assays specifically targeted their respective virus with no false positives detected in animals infected with other common pathogens or in certified specific pathogen-free animals. IMPORTANCE The Pacific white shrimp (Penaeus vannamei) is one of the most valuable aquaculture species in the world but has suffered major economic losses from outbreaks of White Spot Syndrome Virus and Taura Syndrome Virus. Rapid detection of these viruses can improve aquaculture practices by enabling more timely action to be taken to combat disease outbreaks. Highly sensitive, specific, and robust CRISPR-based diagnostic assays such as those developed here have the potential to revolutionize disease management in agriculture and aquaculture helping to promote global food security.

Socio–economic aspects of the integrated gher farming system of Dhopakhali union at Kachua upazila in Bagerhat district, Bangladesh

A study was conducted at Dhopakhali union under Kachua upazila of Bagerhat district in Khulna division from December 2021 to February 2022, with a view to know the current practices of integrated rice–shrimp–prawn–white fish in gher farming system. It was found from this study that 80% farmers acquired experience on gher farming system, and 20% farmers had taken training from GOs, NGOs and other organizations. Among these 80% farmers, 33% farmers acquired their experience by self–study, and the remaining 67% gained experience from friends and neighbors. The average land size in the study area was 0.90 acre or 0.39 ha. The information was collected from 15 farmers with questionnaire interviews, which include the physical condition of the ghers, pre–stocking management, stocking management, post–stocking management, integrated gher farming, social condition of gher farmers, production and cost–benefits. No standard stocking densities were followed by the respondents in the study area and as a result, stocking density was varied from farmer to farmer. During the survey, the average stocking densities of shrimp and prawn were found to be 31,191 PL/ha and 12,686 PL/ha, respectively. The average annual cost of production was 3,47,965.60 BDT/ha in the integrated paddy + shrimp + prawn + white fish + vegetable farming systems. The average annual income was obtained to be 6,60,043.55 BDT/ha from the paddy + shrimp + prawn + white fish + vegetable farming system with a net profit of 3,12,977.94 BDT/ha and the cost–benefit ratio was obtained to be 1.0:1.9. The average annual cost was calculated to be 2,65,436.96 BDT/ha from the only integrated shrimp + prawn + white fish + vegetable without paddy in the gher management systems with an average annual income of 5,29,805.77 BDT/ha. Net profit was estimated to be 2,64,368.81 BDT/ha and the cost–benefit ratio was obtained to be 1.0:2.0 from the only shrimp + prawn + white fish + vegetable without paddy in the integrated gher farming systems. The yield of paddy per year was reported to be 8,034 kg/ha. In the study area, it was found that fish farmers did not have enough credit facilities and sufficient scientific knowledge on the integrated gher farming system. Therefore, they need appropriate training on aquaculture management as well as adequate funding opportunities to improve the gher farming system in a significant manner in commensurate with the national demands.

Acclimation in intertidal animals reduces potential pathogen load and increases survival following a heatwave

Intertidal animals can experience intense heat during a heatwave, leading to mortality. The causes of death for intertidal animals following heatwaves have often been attributed to a breakdown in physiological processes. This, however, contrasts with research in other animals where heatwave mortality is attributed to existing or opportunistic diseases. We acclimated intertidal oysters to four treatment levels, including an antibiotic treatment, and then exposed all treatments to a 50°C heatwave for 2h, replicating what can be experienced on Australian shorelines. We found that both acclimation and antibiotics increased survival and reduced the presence of potential pathogens. Non-acclimated oysters had a significant shift in their microbiome, with increasing abundances of bacteria from the Vibrio genera, including known potential pathogens. Our results demonstrate that bacterial infection plays a pivotal role in post-heatwave mortality. We anticipate these findings to inform the management of aquaculture and intertidal habitats as climate change intensifies.

Microbial community structure and antibiotic resistance profiles in sediments with long-term aquaculture history

The aim of this investigation was to examine the microbial populations and their resistance patterns towards antibiotics, including the impact of nitrogen metabolism in response to the reintroduction of antibiotics, as well as the presence of resistance genes in sediments from shrimp ponds that have been utilized for extended periods of 5, 15, and over 30 years. Results showed that the sediments exhibited a high prevalence of Proteobacteria, Bacteroidetes, Planctomycetes, Chloroflexi, and Oxyphotobacteria as the most abundant bacterial phyla, accounting for 70.35–77.43% of the total bacterial community. The five most abundant phyla of fungi detected in all sediments, namely Rozellomycota, Ascomycota, Aphelidiomycota, Basidiomycota, and Mortierellomycota, constituted 24.26–32.54% of the total fungal community. It was highly probable that the Proteobacteria and Bacteroidetes phyla serve as the primary reservoir of antibiotic-resistant bacteria (ARB) in the sediment, which included various genera like Sulfurovum, Woeseia, Sulfurimonas, Desulfosarcina, and Robiginitalea. Among these genera, Sulfurovum appeared to be the most widespread in the sediment of aquaculture ponds that have been in operation for more than three decades, while Woeseia dominated in ponds that have been recently reclaimed and have a 15-year aquaculture history. Antibiotic resistance genes (ARGs) were categorized into seven distinct groups according to their mechanism of action. The prevalence of multidrug-resistant ARGs was found to be the highest among all types, with an abundance ranging from 8.74 × 10−2 to 1.90 × 10−1 copies per 16S rRNA gene copies. The results of a comparative analysis of sediment samples with varying aquaculture histories indicated that the total relative abundance of ARGs was significantly diminished in sediment with a 15-year aquaculture history as opposed to sediment with either a 5-year or 30-year aquaculture history. Another assessment of antibiotic resistances in aquaculture sediments involved an examination of the effects of reintroducing antibiotics on nitrogen metabolism processes. The findings revealed that the rates of ammonification, nitrification, and denitrification in the sediment with a history of 5 years and 15 years, decreased as the concentration of oxytetracycline increased from 1 to 300, and 2000 mg/kg, and inhibitory effects were found to be less pronounced in sediments with a 5-year history compared to those with a 15-year history. In contrast, oxytetracycline exposure led to a significant decrease in the rates of these processes in aquaculture pond sediments with a >30 years of aquaculture history across all the concentrations tested. The emergence and dissemination of antibiotic resistance profiles in aquaculture environments requires attention in future aquaculture management.

A Review of Antibiotics, Antibiotic Resistant Bacteria, and Resistance Genes in Aquaculture: Occurrence, Contamination, and Transmission.

Antibiotics are commonly used to prevent and control diseases in aquaculture. However, long-term/overuse of antibiotics not only leaves residues but results in the development of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Antibiotics, ARB, and ARGs are widespread in aquaculture ecosystems. However, their impacts and interaction mechanisms in biotic and abiotic media remain to be clarified. In this paper, we summarized the detection methods, present status, and transfer mechanisms of antibiotics, ARB, and ARGs in water, sediment, and aquaculture organisms. Currently, the dominant methods of detecting antibiotics, ARB, and ARGs are UPLC-MS/MS, 16S rRNA sequencing, and metagenomics, respectively. Tetracyclines, macrolides, fluoroquinolones, and sulfonamides are most frequently detected in aquaculture. Generally, antibiotic concentrations and ARG abundance in sediment are much higher than those in water. Yet, no obvious patterns in the category of antibiotics or ARB are present in organisms or the environment. The key mechanisms of resistance to antibiotics in bacteria include reducing the cell membrane permeability, enhancing antibiotic efflux, and structural changes in antibiotic target proteins. Moreover, horizontal transfer is a major pathway for ARGs transfer, including conjugation, transformation, transduction, and vesiculation. Identifying, quantifying, and summarizing the interactions and transmission mechanisms of antibiotics, ARGs, and ARB would provide useful information for future disease diagnosis and scientific management in aquaculture.

Use of geotechnologies for aquaculture site selection: suitability factors and constraints for production in ground-excavated ponds

Remote sensing (RS) and geographic information systems (GIS) have been used to guide the selection of suitable areas for aquaculture. This systematic review synthesizes the key suitability factors and constraints reported in the literature for establishing inland pond aquaculture. We searched for primary studies on Scopus and Web of Science according to preferred reporting items for systemic reviews and meta-analysis (PRISMA) guidelines. Between 1991 and 2020, 354 articles were published in 104 academic journals. The maximum annual number of publications occurred in 2020, with 22 publications, and there is an increasing trend in studies published over the past 30 years. From 12 selected studies, we identified 48 suitability factors, 11 related to soil suitability, 19 to socioeconomic and infrastructure suitability, and 18 to water quality and availability. The most frequently used suitability factors were road proximity, local market center distance, soil texture, soil slope, and water temperature. We listed 15 constraints that restrict or limit the selection of specific geographic locations for inland aquaculture. Urbanized areas, roads, and forests were the most frequently restricted areas. Geotechnologies provide powerful tools for spatial planning and management of aquaculture. Availability, quality, and access to spatial data are critical for the use of geotechnologies in the process of aquaculture site selection.

Coastal Aquaculture Extraction Using GF-3 Fully Polarimetric SAR Imagery: A Framework Integrating UNet++ with Marker-Controlled Watershed Segmentation

Coastal aquaculture monitoring is vital for sustainable offshore aquaculture management. However, the dense distribution and various sizes of aquacultures make it challenging to accurately extract the boundaries of aquaculture ponds. In this study, we develop a novel combined framework that integrates UNet++ with a marker-controlled watershed segmentation strategy to facilitate aquaculture boundary extraction from fully polarimetric GaoFen-3 SAR imagery. First, four polarimetric decomposition algorithms were applied to extract 13 polarimetric scattering features. Together with the nine other polarisation and texture features, a total of 22 polarimetric features were then extracted, among which four were optimised according to the separability index. Subsequently, to reduce the “adhesion” phenomenon and separate adjacent and even adhering ponds into individual aquaculture units, two UNet++ subnetworks were utilised to construct the marker and foreground functions, the results of which were then used in the marker-controlled watershed algorithm to obtain refined aquaculture results. A multiclass segmentation strategy that divides the intermediate markers into three categories (aquaculture, background and dikes) was applied to the marker function. In addition, a boundary patch refinement postprocessing strategy was applied to the two subnetworks to extract and repair the complex/error-prone boundaries of the aquaculture ponds, followed by a morphological operation that was conducted for label augmentation. An experimental investigation performed to extract individual aquacultures in the Yancheng Coastal Wetlands indicated that the crucial features for aquacultures are Shannon entropy (SE), the intensity component of SE (SE_I) and the corresponding mean texture features (Mean_SE and Mean_SE_I). When the optimal features were introduced, our proposed method performed better than standard UNet++ in aquaculture extraction, achieving improvements of 1.8%, 3.2%, 21.7% and 12.1% in F1, IoU, MR and insF1, respectively. The experimental results indicate that the proposed method can handle the adhesion of both adjacent objects and unclear boundaries effectively and capture clear and refined aquaculture boundaries.

Genetic Diversity and Population Structure of the Chinese Mitten Crab (Eriocheir sinensis) from Six Different Lakes Using Microsatellites

The Chinese mitten crab (Eriocheir sinensis) is among the most important species in China and other countries, and it contributes significantly to aquaculture and meeting protein demands for the fast-growing human population. To ensure their sustainable exploitation, management, and use in aquaculture, it is imperative to know their genetic diversity. Thus, we studied the genetic diversity of six populations of Chinese mitten crabs from six different lakes in the Yangtze River’s drainage system. A total of 180 Chinese mittens crabs were collected from six lakes in China, with 30 being collected from each lake. Then, DNA was extracted using TaKaRa Dalian, genotyping was performed by the Gene Marker software for statistical analysis and the genetic parameters such as observed number of alleles (Na)were studied. A total of 87 alleles were observed in 180 individuals of six wild Eriocheir sinensis populations. The Fis results showed that six sites had negative values, and crab20 had the largest value. The results of Fit showed that the single locus had a negative value. All the Fst values among the populations were lower than 0.50, while an AMOVA analysis showed that 0.36% of the genetic variation came from among the six populations and 94.08% of the genetic variation was between individuals in a population. The six Chinese mitten crab populations showed higher genetic variability among individuals of the same population with very low genetic variability between the populations. Therefore, this illustrates that the crabs from the six lakes have similar genetic diversity and minor genetic differences among them.

Application of Deep Learning-Based Object Detection Techniques in Fish Aquaculture: A Review

Automated monitoring and analysis of fish’s growth status and behaviors can help scientific aquaculture management and reduce severe losses due to diseases or overfeeding. With developments in machine vision and deep learning (DL) techniques, DL-based object detection techniques have been extensively applied in aquaculture with the advantage of simultaneously classifying and localizing fish of interest in images. This study reviews the relevant research status of DL-based object detection techniques in fish counting, body length measurement, and individual behavior analysis in aquaculture. The research status is summarized from two aspects: image and video analysis. Moreover, the relevant technical details of DL-based object detection techniques applied to aquaculture are also summarized, including the dataset, image preprocessing methods, typical DL-based object detection algorithms, and evaluation metrics. Finally, the challenges and potential trends of DL-based object detection techniques in aquaculture are concluded and discussed. The review shows that generic DL-based object detection architectures have played important roles in aquaculture.