Search Results (35)

The African catfish, Clarias gariepinus, is among the most farmed fish species in Uganda’s rapidly growing aquaculture sub-sector. The enhanced growth performance, increased survival, and resilience to environmental stressors have driven a rising demand among farmers for improved African catfish broodstock and seed. Until recently, most studies of this species have focused on nutrition, physiology, and culture systems, with little known about the genetics, broodstock, and hatchery management of the cultured C. gariepinus populations. This knowledge gap has led to inbreeding depression, resulting in poor seed quality and reduced performance of the broodstock. To enhance catfish aquaculture production, a survey was conducted across multiple catfish hatcheries and farms in Uganda. Using semi-structured questionnaires, the study assessed broodstock management practices, hatchery propagation methods, the suitability of various populations, demographics, challenges, and prospects of hatchery operators. Responses were coded, and descriptive statistics such as frequency, percentages, and means were calculated. Results indicate that there are farmers who continue to source their broodstocks from the natural water bodies in addition to acquiring them from fellow farmers. The estimated effective population size (Ne) for the majority of the respondents was 133.33 and 178.22, with an average breeding coefficient of 0.4% and 0.3%, respectively. There is also a continuous use of shooters (fast-growing cannibalistic fish) by the farmers who hatch and select them to be used as broodstocks later, under the assumption that they have superior genetic traits. The reported hatchability rate was above 70%, with an average survival rate of 60% from larvae to fry. The study identified diseases, inadequate water supply, and electricity as the primary challenges for catfish breeding. While Uganda’s African catfish aquaculture industry is expanding rapidly, certain hatchery practices pose significant risks to its sustainability if not properly addressed. Full article

Freshwater fishes are one of the most threatened animal taxa in North America. In Canada, roughly 30% of the occurring species are currently listed and under protection, including redhorses. This review covers Moxostoma spp. ecology, biology, conservation efforts, and highlights challenges to galvanize actions and outcomes through research. The threats to their survival are strongly associated to increasing anthropogenic pressures, superimposed by climate change effects. In Canada, recovery plans for the copper and the black redhorse, and a management plan for the river redhorse, are operational. The recovery strategy for the copper redhorse relies on stocking campaigns of 0⁺ juveniles, which was exclusively based on artificial breeding of captured wild broodstock. A conservation aquaculture program that includes genetic diversity and adaptation considerations was recently initiated, and the areas of refinement identified are the following: broodstock and early-life rearing protocols and environmental and physical enrichment protocols to improve juveniles’ post-release fitness. Research through the prism of conservation physiology is proposed in the identification welfare and health bioindicators and adaptability/response to climatic change. Concurrently, aquatic ecosystem protection/restoration, control of invasive species, eDNA detection/telemetry tracking, and post-release monitoring efforts should also be reinforced. Full article

The Peruvian grunt, Anisotremus scapularis, is a commercially valuable coastal fish in the southeastern Pacific that is facing overexploitation. To support its aquaculture development, this study evaluated the spontaneous reproductive dynamics of a captive broodstock held under natural photoperiod and temperature conditions in a flow-through system. Eleven wild adult specimens (3 females and 8 males) with an average size of 34.9 ± 5.4 cm and a weight of 986 ± 470 g were housed in a 9 m³ tank and monitored over five consecutive spawning seasons (2016–2021). Fish were fed a semi-moist, animal-protein-based diet (37% protein and 6.6% lipid) at 2% body weight/day. A total of 214 spontaneous spawning events produced over 83 million eggs. The highest reproductive output occurred in the first season (2016–2017) with 94 spawnings and 23.3 million eggs. Fertilization, hatching, and larval survival rates averaged 94.7%, 89.7%, and 75%, respectively, but declined in later years. Spawning showed marked seasonality from October to May, with a major reproductive pause in late January. The temperature (16–20 °C) and photoperiod (>12 h daylight) appeared to influence reproductive timing, alongside diet and broodstock handling. The findings reported herein are observational in nature and provide valuable baseline data for future experimental designs aimed at optimizing broodstock management in A. scapularis aquaculture. Full article

Viral diseases pose significant threats to aquaculture industries worldwide, including the Australian fish and prawn farming sectors, which contribute over AUD 1.6 billion annually to the national economy. The Australian aquaculture industry relies heavily on wild-caught broodstock for seedstock production, introducing substantial and unprecedented biosecurity risks. This systematic review consolidates current knowledge on the viral pathogens affecting key Australian fish and prawn species, their economic impacts, and the biosecurity measures implemented for mitigation. Notably, viral outbreaks have led to losses exceeding AUD 100 million in some sectors, highlighting the urgent need for improved management. Existing biosecurity strategies, including surveillance systems, molecular diagnostics, and pathogen exclusion protocols, are critically assessed for their effectiveness. Emerging approaches such as genetic resistance breeding, advanced vaccination technologies, and integrated risk management frameworks are also explored. Key knowledge gaps, particularly in the context of emerging viral pathogens and their ecological interactions under changing environmental conditions, are identified as priority areas for future research. This review emphasises the necessity of adopting a multidisciplinary approach to enhance the resilience of Australian aquaculture, advocating for stronger biosecurity frameworks and innovative technologies to mitigate the escalating risks posed by viral diseases. Full article

The increasing global demand for seafood underscores the necessity for sustainable aquaculture practices. However, several challenges, including rising operational costs, variable environmental conditions, and the threat of disease outbreaks, impede progress in this field. This review explores the transformative role of the Artificial Intelligence of Things (AIoT) in mitigating these challenges. We analyse current research on AIoT applications in aquaculture, with a strong emphasis on the use of IoT sensors for real-time data collection and AI algorithms for effective data analysis. Our focus areas include monitoring water quality, implementing smart feeding strategies, detecting diseases, analysing fish behaviour, and employing automated counting techniques. Nevertheless, several research gaps remain, particularly regarding the integration of AI in broodstock management, the development of multimodal AI systems, and challenges regarding model generalization. Future advancements in AIoT should prioritise real-time adaptability, cost-effectiveness, and sustainability while emphasizing the importance of multimodal systems, advanced biosensing capabilities, and digital twin technologies. In conclusion, while AIoT presents substantial opportunities for enhancing aquaculture practices, successful implementation will depend on overcoming challenges related to scalability, cost, and technical expertise, improving models’ adaptability, and ensuring environmental sustainability. Full article

Geoduck aquaculture is becoming a key component in meeting international market demand, given the natural and regulatory restrictions on wild geoduck supply. Geoduck clams are not sexually dimorphic, making it practically unfeasible to distinguish between males and females prior to a spawning event. To facilitate increased production of geoduck, a better understanding of reproductive biology and associated targeted bio-markers is required. In this study, metabolomics was utilised as a research tool to distinguish between metabolites related to male and female New Zealand geoduck (Panopea zelandica), gill and muscle samples collected from broodstock individuals housed in an experimental hatchery. A total of 17 metabolites were detected, showing significant differences between sexes. The findings indicate that metabolites associated with lipid biosynthesis were increased in female clams to support reproductive functions. An increase in carbohydrate-linked metabolic pathways was detected in male geoduck, arguably to sustain sperm production. Taurine has been reported as a biomarker to distinguish between male and female bivalves in other studies and is confirmed within this study, with significant elevation in male adductor muscle tissue. Moreover, male geoduck had increased purine and pyrimidine biosynthesis, supporting energy needs. This study provides useful sex biomarkers for future breeding strategies of P. zelandica. Full article

Background: Walleye (Sander vitreus), a valuable sportfish and an important ecological apex predator, exhibits genetic structuring across their range and localized structuring as a result of stocking. Methods: Walleye from 17 sampling locations across West Virginia were sequenced using a ddRAD protocol, generating various SNP datasets to assess population structuring and genomic diversity, with specific emphasis on the native Eastern Highlands strain. Different minor allele frequency filter thresholds were tested to assess impacts on genetic diversity and differentiation metrics. Results: High genetic differentiation was observed between the Eastern Highlands and Great Lakes strains, with further sub-structuring within the Eastern Highlands strain between the Ohio River populations and the other populations. Increasing MAF thresholds generally reduced the distinctiveness of clusters, but the overall inference of the number of clusters was minimally impacted. Genetic diversity metrics indicated some variability among Eastern Highlands walleye populations, with isolated populations, including the New River and Summersville Lake, showing higher inbreeding coefficients. MAF filters generally increased diversity metrics, but the trend of diversity metrics among populations remained relatively consistent. Several SNPs were found to be potentially undergoing selection, with the minor allele frequencies of these SNPs being found to be highest in Summersville Lake, highlighting potential adaptive divergence between the riverine populations and a large lentic system. Conclusions: The use of any MAF filter generated the same trends of population structuring and genomic diversity inferences regardless of the MAF threshold used. Further management of Eastern Highlands walleye in West Virginia needs to emphasize protecting the genetic integrity of the Kanawha River population and ongoing genomic screening of broodstock to conserve native genetic diversity. Full article

The Peruvian grunt Anisotremus scapularis is one of the most appreciated fish in Peruvian national markets. However, its reduced and irregular fishery is a paradigm of illegal, unreported, and unregulated fishing (IUU) in the Peruvian–Chilean coastal region. An important technological advancement has been achieved in the last decade in capture, management, nutrition, and broodstock maintenance to boost pilot experiences on the aquaculture of this species. Therefore, it is pertinent to evaluate the economic viability of this candidate species to identify cultivation bottlenecks, optimize the process, and assess the transfer feasibility of the technical know-how to interest groups. In this study, we performed a sensitivity analysis to assess how market price and production size should make its commercialization profitable. We show that the use of photovoltaic solar panels and a raw production cycle of 15 months enables profitability at a ~400 k unit farm size at a commercial market price of 6.67 USD/kg, i.e., B/C = USD 1.14. Both, time to market and market price exerted the highest influence on the value of grunt farms; whereas, a reduction of the production cycle to 12 months by seed selection, optimized rearing conditions, and nutritional diets also provides a profitable investment, i.e., NPV = USD 287,054 with an IRR = 23.71% at a discount rate of 10% and B/C = USD 1.15. These scenarios pave the way for the transfer of technological know-how to entrepreneurial initiatives in the economically depressed coastal region of the Atacama Desert. Full article

Vaccination is an essential method of immunological preventive care required for the health management of all animals, including fish. More particularly, immunization is necessary for in-land aquaculture to manage diseases in fish broodstocks and healthy seed production. According to the latest statistics in 2020, 90.3 million tons of capture fishery production was achieved from the aquaculture sector. Out of the above, 78.8 million tons were from marine water aquaculture sectors, and 11.5 million tons were from inland water aquaculture sectors. About a 4% decline in fish production was achieved in 2020 in comparison to 2018 from inland aquaculture sectors. On the other hand, the digestive protein content, healthy fats, and nutritional values of fish products are comparatively more affordable than in other meat sources. In 2014, about 10% of aquatic cultured animals were lost (costing global annual losses > USD 10 billion) due to infectious diseases. Therefore, vaccination in fish, especially in broodstocks, is one of the essential approaches to stop such losses in the aquaculture sector. Fish vaccines consist of whole-killed pathogens, protein subunits, recombinant proteins, DNA, or live-attenuated vaccines. Challenges persist in the adaption of vaccination in the aquaculture sector, the route of administration, the use of effective adjuvants, and, most importantly, the lack of effective results. The use of autogenous vaccines; vaccination via intramuscular, intraperitoneal, or oral routes; and, most importantly, adding vaccines in feed using top dressing methods or as a constituent in fish feed are now emerging. These methods will lower the risk of using antibiotics in cultured water by reducing environmental contamination. Full article

During a suspension of a GIFT tilapia broodstock recirculating aquaculture system (RAS), a significant fish mortality event occurred. To determine the cause, four bacterial strains were isolated from affected fish and identified as Vibrio vulnificus through 16S rDNA sequencing. Virulence assays confirmed the pathogenicity of these strains, with the most virulent, CS-4, selected for a further analysis. Antimicrobial testing revealed CS-4’s sensitivity to 19 antibiotics, including meloxicillin and Gentamicin. Challenge tests indicated varied 7-day Lethal Dose 50 (LD₅₀) values for CS-4 depending on the infection route, with immersion after skin injury being the most lethal. Additionally, the effects of salinity, crowding with air exposure, and nitrite on tilapia mortality were evaluated. The results showed that salinity stress increased the mortality rate of tilapia infected with V. vulnificus through immersion, and that salinity stress and V. vulnificus infection had a synergistic effect. A 20 min crowding with air exposure stress reduced the mortality rate of Nile tilapia infected with V. vulnificus. Nitrite stress had little effect on the mortality rate of tilapia infected with V. vulnificus. The results of the risk factor analysis indicated that salinity was the main factor affecting tilapia mortality caused by V. vulnificus infection. This study will serve as a valuable reference for the future management of similar RAS. Full article

Walleye, Sander vitreus, has several distinct genetic lineages throughout North America as a consequence of Pleistocene glaciation. Stocking walleye across genetic boundaries in the mid-20th century has led to the introduction of non-native strains that persist to this day. In West Virginia, the identification of the native Eastern Highlands strain led the West Virginia Division of Natural Resources (WVDNR) to employ broodstock screening to assist in the conservation of the native strain. To develop a baseline native ancestry prevalence in walleye populations throughout the state, 1532 broodstock were sampled across 17 sampling locations over a 6-year period. To evaluate the effectiveness of the current broodstock two-SNP qPCR assay protocol and identify whether more SNPs need to be implemented, 284 walleye were sequenced and ancestry-genotyped across 42 fixed SNPs between the two strains. When comparing the current protocol to the older microsatellite protocol, advancement in the ability to identify native-strain individuals was observed. Genotyping previously assigned walleye broodstock across multiple fixed SNPs revealed that the current ancestry assignment protocol, on average, assigned individuals that display 96% Eastern Highlands native ancestry to the native strain and accurately identified >93% of all pure Eastern Highlands walleye. Throughout the state of West Virginia, the New and Kanawha River systems contained a high prevalence of native ancestry, with the Ohio River and sampled impoundments displaying varying levels of ancestry. SNPs with >98% prevalence in individuals assigned to the Eastern Highlands strain were identified during the course of the study and can be implemented in future screening protocols. Our results highlight the utility of genomic approaches as tools to assist fisheries management goals and their capability to accurately identify native ancestry to assist in conservation efforts. Full article

The Pacific blue shrimp (Litopenaeus stylirostris) is a premium product in the international seafood market. However, intensified farming has increased disease incidence and reduced genetic diversity. In this study, we developed a transcriptome database for L. stylirostris and mined microsatellite markers to analyze their genetic diversity. Using the Illumina HiSeq 4000 platform, we identified 53,263 unigenes from muscle, hepatopancreas, the intestine, and lymphoid tissues. Microsatellite analysis identified 36,415 markers from 18,657 unigenes, predominantly dinucleotide repeats. Functional annotation highlighted key disease resistance pathways and enriched categories. The screening and PCR testing of 42 transcriptome-based and 58 literature-based markers identified 40 with successful amplification. The genotyping of 200 broodstock samples revealed that Na, H_o, H_e, PIC, and F_IS values were 3, 0.54 ± 0.05, 0.43 ± 0.09, 0.41 ± 0.22, and 0.17 ± 0.27, respectively, indicating moderate genetic variability and significant inbreeding. Four universal microsatellite markers (CL1472.Contig13, CL517.Contig2, Unigene5692, and Unigene7147) were identified for precise diversity analysis in Pacific blue, Pacific white (Litopenaeus vannamei), and black tiger shrimps (Penaeus monodon). The transcriptome database supports the development of markers and functional gene analysis for selective breeding programs. Our findings underscore the need for an appropriate genetic management system to mitigate inbreeding depression, reduce disease susceptibility, and preserve genetic diversity in farmed shrimp populations. Full article

The sterlet (Acipenser ruthenus) is the smallest-bodied endangered species among the six native sturgeon species of the Danube River, and self-sustaining populations still inhabit the Hungarian section of the Danube River and its largest tributary, the Tisza River. Their populations are drastically decreasing; however, they still have natural reproduction in these habitats. For the genetic conservation of the species, an ex situ gene bank is maintained in Hungary. The present study aimed to analyze the genetic resources of a gene bank with a near 40-year history and to compare it with natural populations and farmed stocks. Twelve microsatellites were used for population genetics analyses and individual genotyping of 268 specimens from two natural habitats (Danube and Tisza Rivers) and three captive stocks (a gene bank broodstock and two farms). Microsatellites revealed similar patterns among wild populations and gene bank stocks and did not show genetic differentiation (F_ST: 0.016–0.017) among them. These results confirmed that the gene bank broodstock properly represents the genetic background of the Danube and Tisza populations and is suitable as a source of breeding materials for the restocking programs. Negative trends were detected in the farmed stocks, reflected in reduced polymorphism at a few loci. The results of the principal component analyses indicate the farm stocks’ separation from the wild and gene bank stocks. The present genetic characterization study reveals a valuable captive stock of the endangered sterlet populations and provides unique information about the genetic similarities and differences among farms and wild stocks in Hungary. Our results provide information that contributes to preserving the genetic structure and variability in sterlet populations and supports the management of gene bank broodstock—avoiding inbreeding and preserving the unique genetic background of the Carpathian basin. Full article

Cyprinids include some of the most widely farmed freshwater species. The aim of this study was to assess the incidence of skeletal malformations in carp species reared in semi-intensive systems in Albania: common carp (Cyprinus carpio), silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idella) and bighead carp (Hypophthalmichthys nobilis). The common carp fingerlings had a mean total length of 28.9 ± 5.0 mm; the frequencies of individuals with at least one anomaly and at least one severe anomaly were 79.2% and 43.4%, respectively. The silver carp juveniles had a mean total length of 21.6 ± 2.1 mm; the frequencies of individuals with at least one anomaly and one severe anomaly were 93.1% and 57.5%, respectively. The grass carp fry had a mean total length of 33.5 ± 2.6 mm; all the analyzed specimens showed almost one anomaly and 86.4% showed at least one severe anomaly. The bighead carp juveniles had a mean total length of 34.4 ± 5.7 mm; the frequencies of individuals with at least one anomaly and at least one severe anomaly were 95.0% and 62.5%, respectively. The development of a more suitable feeding protocol for herbivorous species and the setting up of more efficient broodstock management protocols are suggested to reduce the high incidence of skeletal malformations. Full article

Aquaculture of the lumpfish (Cyclopterus lumpus L.) has become a large, lucrative industry owing to the escalating demand for “cleaner fish” to minimise sea lice infestations in Atlantic salmon mariculture farms. We used over 10K genome-wide single nucleotide polymorphisms (SNPs) to investigate the spatial patterns of genomic variation in the lumpfish along the coast of Norway and across the North Atlantic. Moreover, we applied three genome scans for outliers and two genotype–environment association tests to assess the signatures and patterns of local adaptation under extensive gene flow. With our ‘global’ sampling regime, we found two major genetic groups of lumpfish, i.e., the western and eastern Atlantic. Regionally in Norway, we found marginal evidence of population structure, where the population genomic analysis revealed a small portion of individuals with a different genetic ancestry. Nevertheless, we found strong support for local adaption under high gene flow in the Norwegian lumpfish and identified over 380 high-confidence environment-associated loci linked to gene sets with a key role in biological processes associated with environmental pressures and embryonic development. Our results bridge population genetic/genomics studies with seascape genomics studies and will facilitate genome-enabled monitoring of the genetic impacts of escapees and allow for genetic-informed broodstock selection and management in Norway. Full article