Effects of in ovo vaccination time on broiler performance parameters under field conditions

Hatchery performance is often evaluated based on descriptors such as hatchability, 7-d mortality, and cost. In addition to these descriptors, it is useful to include in this analysis aspects of chick quality through post-hatch performance. Realizing the bird's complete genetic potential necessitates meeting various criteria, with effective support for the chick's immune system being among the pivotal factors. To be effective, in ovo vaccination systems must deliver the vaccines to specific sites in the egg, a circumstance that directly depends on when the injection is made. We examined production data to evaluate the impact of in ovo vaccination time on performance parameters of male Ross308AP chicks. A comprehensive survey was conducted examining records from 3,722 broiler flocks produced and raised by the same company under standard nutrition and management conditions. The selected data specifically pertained to flocks that underwent slaughter between 41 and 45 d. In our analysis, 4 different linear models were built, one for each response variable: mean weight (MW), body weight gain (BWG), corrected feeding conversion rate (cFCR), and total mortality (TM). The linear models used in the analyses included as main predictor the timing of in ovo vaccination (440, 444, 448, 452, 456, 458, and 460 h of incubation), and as additional predictors: age of the breeding flock (26-35, 36-55 and 56-66 wks old), slaughter age, identity of the hatchery, and the season at which the data was collected. Our results showed that the timing of in ovo vaccination significantly affected BWG and cFCR, with procedures performed at 460 h of incubation showing the best outcomes. Breeding flock age affected all response variables, with older breeding flocks delivering increased MW, BWG and TM, and middle-aged flocks increased cFCR. Increasing slaughter age reduced BWG while MW, cFCR and TM were all increased. These data emphasize the benefits of performing in ovo vaccination as close as possible to 460 h of incubation to extract the best BWG and cFCR from Ross308AP male broiler.

Draft genome sequence of Bacillus velezensis strain 3TSA-3, a potential probiotic for Pacific white shrimp Penaeus vannamei postlarvae isolated from commercial hatchery tanks

We report the draft genome of Bacillus velezensis strain 3TSA-3, isolated from Pacific white shrimp Penaeus vannamei postlarvae collected from a hatchery tank with high survival despite the presence of pathogenic Vibrio. The strain possesses genes encoding bacteriocins and lacks virulence factor genes, characteristics for a potential aquaculture probiotic.

Hatchery Losses in Flocks of Layer and Broiler Breeders Due to Feed Contamination with Nicarbazin and Narasin: A Case Report

In the current study, we investigated decreased hatchability and increased embryonic mortality in two farms of layer breeders (flocks A1 and B1) and a farm of broiler breeders (flocks C1 and C2) from Austria, which also presented discoloration of eggshells in 2% of the eggs. After conducting clinical evaluations and the approval that the feed operator was common for flocks A1 and B1, and C1 and C2, it was decided to investigate the feed. Our findings revealed that the feed contained levels of nicarbazin and narasin up to five and 14 times, respectively, above the maximum limits allowed by the European Union for nontarget species. On the other hand, there were no significant abnormalities in vitamin levels, which were also described as the etiology of the noticed abnormalities. Switching to a noncontaminated feed resulted in the clinical signs and production parameters returning to expected ranges. This report emphasizes the significance of considering feed contamination by nicarbazin and narasin as a potential cause of hatchery losses in nontarget species, even in the absence of other clinical signs.

The impact of dissolved oxygen concentration on the swimming performance and welfare of ballan wrasse (Labrus bergylta Ascanius, 1767)

Sea lice (Lepeophtheirus salmonis [Krøyer, 1838]) are a key issue for salmon aquaculture, contributing to increased mortality for both wild and farmed salmon if no action is taken. Using cleaner fish can be an effective, drug-free treatment method, and ballan wrasse (Labrus bergylta) is a hardy wrasse species that displays cleaning behavior. With concerns about the overharvest of wild ballan wrasse, many companies farm this species, but the optimal ranges of a wide variety of rearing parameters are still unknown. This study investigated the effect of 6-week exposure to four dissolved oxygen (DO) levels (125%, 100%, 85%, and 75% DO saturation as the percentage of air) on ballan wrasse. Survival; growth (specific growth rate, SGR); condition factor (CF); and primary (cortisol), secondary (glucose, lactate, magnesium), and tertiary stress indicators (swimming performance) were investigated. There were no differences in SGR, CF, survival, or cortisol level among the groups at the end of the 6 weeks. There was variation in the magnitude of the cortisol response to an acute stressor at the end of the 6-week period, with the 75% DO treatment exhibiting a 3.3-fold increase in cortisol compared to a 5.2-fold increase in the control group (100%), which could suggest chronic stress. Relative critical swimming speed (RUcrit ) was measured to investigate swimming performance once all groups were returned to 100% DO saturation. The 75% RUcrit was lower than the 100% treatment (1.7 ± 0.18 body length [BL]/s compared to 2.5 ± 0.16 BL/s). Overall, these results suggest that DO levels of 75% trigger physiological changes and therefore may negatively affect welfare.

Genomic evidence for domestication selection in three hatchery populations of Chinook salmon, Oncorhynchus tshawytscha

Fish hatcheries are widely used to enhance fisheries and supplement declining wild populations. However, substantial evidence suggests that hatchery fish are subject to differential selection pressures compared to their wild counterparts. Domestication selection, or adaptation to the hatchery environment, poses a risk to wild populations if traits specific to success in the hatchery environment have a genetic component and there is subsequent introgression between hatchery and wild fish. Few studies have investigated domestication selection in hatcheries on a genomic level, and even fewer have done so in parallel across multiple hatchery-wild population pairs. In this study, we used low-coverage whole-genome sequencing to investigate signals of domestication selection in three separate hatchery populations of Chinook salmon, Oncorhynchus tshawytscha, after approximately seven generations of divergence from their corresponding wild progenitor populations. We sequenced 192 individuals from populations across Southeast Alaska and estimated genotype likelihoods at over six million loci. We discovered a total of 14 outlier peaks displaying high genetic differentiation (F ST) between hatchery-wild pairs, although no peaks were shared across the three comparisons. Peaks were small (53 kb on average) and often displayed elevated absolute genetic divergence (D xy) and linkage disequilibrium, suggesting some level of domestication selection has occurred. Our study provides evidence that domestication selection can lead to genetic differences between hatchery and wild populations in only a few generations. Additionally, our data suggest that population-specific adaptation to hatchery environments likely occurs through different genetic pathways, even for populations with similar standing genetic variation. These results highlight the need to collect paired genotype-phenotype data to understand how domestication may be affecting fitness and to identify potential management practices that may mitigate genetic risks despite multiple pathways of domestication.

Achieving conservation and restoration outcomes through ecologically beneficial aquaculture

A range of conservation and restoration tools are needed to safeguard the structure and function of aquatic ecosystems. Aquaculture, the culturing of aquatic organisms, often contributes to the numerous stressors that aquatic ecosystems face, yet some aquaculture activities can also deliver ecological benefits. We reviewed the literature on aquaculture activities that may contribute to conservation and restoration outcomes, either by enhancing the persistence or recovery of one or more target species or by moving aquatic ecosystems toward a target state. We identified 12 ecologically beneficial outcomes achievable via aquaculture: species recovery, habitat restoration, habitat rehabilitation, habitat protection, bioremediation, assisted evolution, climate change mitigation, wild harvest replacement, coastal defense, removal of overabundant species, biological control, and ex situ conservation. This list may be expanded as new applications are discovered. Positive intentions do not guarantee positive ecological outcomes, so it is critical that potentially ecologically beneficial aquaculture activities be evaluated via clear and measurable indicators of success to reduce potential abuse by greenwashing. Unanimity on outcomes, indicators, and related terminology will bring the field of aquaculture-environment interactions into line with consensus standards in conservation and restoration ecology. Broad consensus will also aid the development of future certification schemes for ecologically beneficial aquaculture.

Influence of Pediveliger Larvae Stocking Density on Settlement Efficiency and Seed Production in Captivity of Mytilus galloprovincialis in Amsa Bay, Tetouan

In mussel hatchery systems, the settlement process is a crucial element influencing seed yield. The current study assayed the influence of five densities of competent pediveliger larvae on settlement success and post-larvae production. We showed an inverse relationship between density and settlement efficiency, e.g., an attachment success of 99.4% at the lowest density (35 larvae/cm2) but only 9% at the highest density (210 larvae/cm2). However, post-larvae production was higher at intermediate larvae densities (70 larvae/cm2). The reimplementation of treatments upon post-larvae density after 6 weeks post settlement showed that the lowest-density groups bore both the highest post-larvae growth rate (22.24 ± 4.60 µm/day) and the largest head batch (48% of the size distribution), as compared to the higher-post-larvae-density groups. These results highlight the importance of optimizing both pediveliger larvae density and post-larvae density, to maximize high-quality seed yield in local hatcheries. Current rearing technologies would assure a timely commercial seed production to protect natural sea rocky beds in Alboran Sea coasts.

Investigation of aspergillosis outbreak in young ducklings: Unraveling the role of hatcheries in Aspergillus fumigatus transmission

Objective

Aspergillosis is a disease that affects several species of birds and causes substantial losses in the poultry business. The purpose of the investigation was to identify the pathogen responsible for a respiratory outbreak among juvenile ducklings.

Materials and Methods

An epidemic of Aspergillosis infected a total of 800 Muscovy ducks that were being reared in El-Beheira Governorate. Tissue samples were obtained to isolate suspected fungi from diseased birds and the hatchery environment. In addition, identification and molecular characterization were performed on the obtained fungal isolates.

Results

Affected birds displayed acute respiratory manifestations such as difficulty breathing, gasping for air, nasal discharge, and a mortality rate of up to 28.1%. Postmortem examination revealed bronchitis, tracheitis, congested lungs, air sacculitis, severe multifocal granulomatous pneumonia, a congested, enlarged liver, and a congested kidney with nephritis. Mycological examination revealed seven Aspergillus (A.) spp. isolates from ducklings and six from hatcheries. Isolate colonial morphology and microscopical examination were as follows: A. fumigatus, A. niger, Syncephalastrum racemosum, and four untypable isolates. These isolates were further identified by polymerase chain reaction (PCR), and the internal transcribed spacers (ITSs) gene was detected. Four representative isolates were submitted for sequencing and further phylogenetic analysis. The source of duckling infection might be linked to the hatchery environment due to the observed similarity of isolates from both affected birds and the hatchery, as evidenced by phylogenetic analysis.

Conclusion

Our findings demonstrated the significance of appropriate hatchery control in preventing infection in young ducklings. Furthermore, the use of molecular identification techniques would be helpful for tracing the source of infection and rapid diagnosis of Aspergillus in the field.

Dominant Salmonella Serovars in Australian Broiler Breeder Flocks and Hatcheries: a Longitudinal Study

A longitudinal study was conducted to determine the dominance and prevalence of Salmonella enterica subsp in Australian broiler breeder flocks and hatcheries. Twenty-two flocks (n = 3339 samples) were sampled over 6 time points beginning at placement until week 40. Hatcheries (n = 274 samples) were sampled following removal of chicks hatched from eggs originating from the 22 donor parent flocks. The percent of positive flocks (36%) and frequency of positive samples (15.6%) were highest during rearing at week 7. The frequency of positive samples decreased over the 40 weeks; however, the number of positive flocks remained relatively consistent. Geographical location had a greater influence on Salmonella detection frequency than company sample origin, despite differing management and vaccination protocols within and between companies. Twelve serovars were detected in total. The predominant serovars during rearing were Salmonella Mbandaka (32%), S. Saintpaul (27%), and S. Liverpool (18%). The predominant serovars detected during production were S. Cubana (27%), S. Saintpaul (24%), and S. Havana (13%). Salmonella Typhimurium, S. Ohio, and S. Hessarek were detected in the hatcheries. Of the serovars detected, only S. Typhimurium and S. Ohio were found in both broiler breeder flocks and hatcheries. However, detection did not correspond to the status of the flock eggs feeding into the hatchery. This study provides an up-to-date capture of the current Salmonella serovars circulating in the broiler breeder industry. Continued surveillance within the Australian Chicken Meat industry is imperative to mitigate and reduce the risk of salmonellosis in the community related to chicken meat. IMPORTANCE This study identified prevalent and dominant Salmonella enterica subsp in Australian Broiler Breeder flocks, as well as in hatcheries post chick hatch and removal, from eggs originating from these donor parent flocks. The captured Salmonella data was further compared to the most common Salmonella serovars isolated from broilers, as well as human salmonellosis notification data, which is useful for consideration of the circulating serovars within the chicken meat industry and their significance in public health. As there are multiple entry points for Salmonella during the entire chicken meat production chain that can lead to carcass contamination, it is important to distinguish serovars present between the different stages of vertical integration to implement and enable Salmonella control strategies.

Evaluation of the impact of formaldehyde fumigation during the hatching phase on contamination in the hatch cabinet and early performance in broiler chickens

Commercial hatch cabinet environments promote replication of microorganisms. These pathogenic or apathogenic microorganisms may serve as pioneer colonizers of the gastrointestinal tract (GIT) of poultry. Some of these pioneer colonizers, such as Escherichia coli and Enterococcus spp., are opportunistic pathogens that lead to reduced performance in commercial poultry. Effective hatchery sanitation is imperative to limit contamination of naïve neonatal chicks and poults. Formaldehyde fumigation has been traditionally used to reduce the pathogen load in commercial hatch cabinets. To investigate potential alternatives to formaldehyde fumigation, models to mimic the microbial bloom in a laboratory setting must be utilized. The purpose of the present study was to evaluate the impact of a multispecies environmental challenge model (PM challenge) with and without formaldehyde fumigation during the hatching phase on early performance in broiler chicks. Three experiments were conducted to evaluate microbial contamination in the hatch cabinet environment (air samples, fluff samples), enteric colonization at day-of-hatch (DOH), and 7-day performance. In all experiments, significantly (P < 0.05) more gram-negative bacteria were recovered from the GIT at DOH in the PM challenge control group as compared to the nonchallenged control (NC) group and the formaldehyde-treated group (PM + F). There were no statistical differences in 7-day body weight gain or feed conversion ratio between the PM challenge control group, the NC group or the PM + F group. These data suggest this model could be utilized to evaluate alternatives to formaldehyde fumigation for controlling the microbial load during the hatching phase in a laboratory setting.

Thiamine Supplementation Improves Survival and Body Condition of Hatchery-Reared Steelhead (Oncorhynchus mykiss) in Oregon

Early rearing of steelhead (Oncorhynchus mykiss) in Oregon hatcheries is often problematic; fry can become emaciated and die during the period between hatch and first feed. Thiamine (vitamin B1) deficiency has caused early mortality in salmonids; however, the thiamine status of Oregon's steelhead populations is unknown, to date. Of the 26 egg samples from three Oregon hatcheries in 2019, 20 (77%) had thiamine levels < 10 nmol/g, and 13 of those samples (50%) had levels <6.5 nmol/g, suggesting the thiamine deficiency of adult, female steelhead. To investigate if thiamine deficiency was causally related to fry survival, females were injected with buffered thiamine HCl 50 mg/kg prior to spawning; additionally, a subset of eggs were supplemented via bath treatment with thiamine mononitrate (1000 ppm) at spawning. Cumulative fry mortality at 8 weeks post-hatch from thiamine-injected females was 2.9% compared to 13.8% mortality of fry without thiamine supplementation. Fry treated only with the thiamine via bath as eggs had a mortality rate of 6.9%. There were no additional improvements for the survival of fry from injected females that also received a thiamine bath. Furthermore, condition factors were greater in thiamine-supplemented fry than in those that received no thiamine. These data identify thiamine deficiency in Oregon steelhead and suggest supplementation with thiamine can mitigate early rearing mortality.

Partial-year continuous light treatment reduces precocious maturation in age 1+ hatchery-reared male spring Chinook Salmon (Oncorhynchus tshawytscha)

Hatchery programs designed to conserve and increase the abundance of natural populations of spring Chinook Salmon Oncorhynchus tshawytscha have reported high proportions of males precociously maturing at age 2, called minijacks. High proportions of minijacks detract from hatchery supplementation, conservation and production goals. This study tested the effects of rearing juvenile Chinook Salmon under continuous light (LL) on minijack maturation in two trials. The controls were maintained on a simulated natural photoperiod for both trials. For trial 1, LL treatment began on the summer solstice 2019 or the autumn equinox 2019 and ended in late March 2020 (LL-Jun-Apr and LL-Sep-Apr, respectively). A significant reduction in the mean percent of minijacks (%MJ) was observed versus control (28.8%MJ) in both LL-Jun-Apr (5.4%MJ) and LL-Sep-Apr (9.3%MJ). Trial 2 was designed to evaluate whether stopping LL treatment sooner was still effective at reducing maturation proportions relative to controls. LL treatments began on the summer solstice 2020 and continued until the winter solstice (LL-Jun-Dec) or the final sampling in April 2021 (LL-June-Apr). LL-Jun-Dec tanks were returned to a simulated natural photoperiod after the winter solstice. Both photoperiod treatments showed a significant reduction in mean %MJ from the control (66%MJ): LL-Jun-Dec (11.6%MJ), LL-Jun-Apr (10.3%MJ). In both trials, minijacks had higher body weights, were longer and had increased condition factor when compared to females and immature males in all treatment groups at the final sampling. In both trials, there was little or no effect of LL treatment on fork length or body weight in immature males and females versus controls, but an increase in condition factor versus controls was observed. This study shows that continuous light treatment reduces minijack maturation in juvenile male spring Chinook Salmon and could provide an effective method for Spring Chinook Salmon hatcheries interested in reducing minijack production.

Environment and genotype predict the genomic nature of domestication of salmonids as revealed by gene expression

Billions of salmonids are produced annually by artificial reproduction for harvest and conservation. Morphologically, behaviourally and physiologically these fish differ from wild-born fish, including in ways consistent with domestication. Unlike most studied domesticates, which diverged from wild ancestors millennia ago, salmonids offer a tractable model for early-stage domestication. Here, we review a fundamental mechanism for domestication-driven differences in early-stage domestication, differentially expressed genes (DEGs), in salmonids. We found 34 publications examining DEGs under domestication driven by environment and genotype, covering six species, over a range of life-history stages and tissues. Three trends emerged. First, domesticated genotypes have increased expression of growth hormone and related metabolic genes, with differences magnified under artificial environments with increased food. Regulatory consequences of these DEGs potentially drive overall DEG patterns. Second, immune genes are often DEGs under domestication and not simply owing to release from growth-immune trade-offs under increased food. Third, domesticated genotypes exhibit reduced gene expression plasticity, with plasticity further reduced in low-complexity environments typical of production systems. Recommendations for experimental design improvements, coupled with tissue-specific expression and emerging analytical approaches for DEGs present tractable avenues to understand the evolution of domestication in salmonids and other species.

Assessing the Likelihood of High Pathogenicity Avian Influenza Incursion Into the Gamebird Sector in Great Britain via Designated Hatcheries

The outbreaks of High Pathogenicity Avian Influenza (HPAI) in the United Kingdom in 2017 and 2021 had a substantial impact on the gamebird industry and highlighted to policymakers the importance of existing knowledge gaps for effective disease control. Despite the size of the industry, the impact of HPAI on the gamebird industry is not well-understood. To improve future disease preparedness, a veterinary risk assessment to explore the risk of HPAI incursion into the gamebird sector in Great Britain via a designated hatchery was commissioned by Scottish Government Animal Health and Welfare Division. Hatchery designation is a legal requirement for hatcheries located within disease control zones or that have business links to premises located in disease control zones to continue operating during an HPAI outbreak. Several risk pathways were identified, which involved various management procedures associated with egg production through to the delivery of day-old chicks. The overall likelihood of the HPAI virus introduction into a designated hatchery through hatching egg movement is considered to be low (high uncertainty). The overall likelihood of onward transmission of the HPAI virus into gamebird rearing sites from a designated hatchery through day-old chick movement is also considered to be low (medium uncertainty). These risk levels are based on the assumption that relevant control measures are observed, as enhanced biosecurity is one of the requirements for hatchery designation. However, high uncertainties and variabilities were identified in the level of compliance with these biosecurity measures. Factors increasing the likelihood level include management practices typical to this sector, such as having multiple egg production sites, raising birds at outdoor sites, catching birds from the wild for egg production, having various scale of satellite farms in various locations, importing eggs and day-old chicks from overseas, as well as the proximity of the game farm to the infected premise or to higher risk areas. This study offers evidence for policymakers to help develop criteria for hatchery designation and proposes important mitigation strategies for future disease outbreaks specific for the gamebird sector.

Genomic Resources for Salminus brasiliensis

The Neotropical region bears the most diverse freshwater fish fauna on the planet and is the stage for dramatic conservation struggles. Initiatives aiming for conservation of a single emblematic fish, a flagship species, to which different onlookers relate on a cultural/personal level, holds promise towards engagement and conservation actions benefiting whole biological communities and ecosystems. Here, we present the first comprehensive genomic resources for Salminus brasiliensis, a potential flagship Neotropical species. This fish faces pressing conservation issues, as well as taxonomic uncertainty, being a main species relevant to angling and commercial fisheries. We make available 178 million Illumina paired-end reads, 90 bases long, comprising 16 Gb (≈15X coverage) of filtered data, obtained from a primary genomic library of 500-bp fragments. We present the first de novo genomic assembly for S. brasiliensis, with ∼1 Gb (N₅₀ = 10,889), as well as the coding genome annotation of 12,962 putative genes from assembled genomic fragments over 10 kb, most of which could be identified from the Ostariophysi GenBank database. We also provide a genome-wide panel for more than 80,000 predicted microsatellite loci for low-cost, fast and abundant DNA marker development for this species. A total of 47, among 52 candidates, empirically assayed microsatellites were confirmed as polymorphic in this fish. All genomic data produced for S. brasiliensis is hereby made publicly accessible. With the disclosure of these results, we intend to foster general biology studies and to provide tools to be applied immediately in conservation and aquaculture in this candidate flagship Neotropical species.

Observations on the distribution and control of Salmonella in commercial broiler hatcheries in Great Britain

Salmonella can enter hatcheries via contaminated eggs and other breaches of biosecurity. The study examined the prevalence and distribution of Salmonella in commercial hatcheries and assessed the effects of providing advice on Salmonella control. Intensive swab sampling was performed throughout 23 broiler hatcheries in Great Britain (GB). Swabs were cultured using a modified ISO6579:2017 method. After each visit, tailored advice on biosecurity and cleaning and disinfection procedures was provided to the hatchery managers. Repeat sampling was carried out in 10 of the 23 hatcheries. Salmonella prevalence ranged between 0% and 33.5%, with the chick handling areas, hatcher areas, macerator area, tray wash/storage areas, external areas and other waste handling areas being more contaminated than the setter areas. Salmonella Senftenberg and Salmonella 13,23:i:‐ were the most commonly isolated serovars. There was a reduction in Salmonella prevalence at the second visit in eight out of 10 premises, but prevalence values had increased again in all of the improved hatcheries that were visited a third time. One hatchery harboured a difficult‐to‐control resident Salmonella 13,23:i:‐ strain and was visited six times; by the final visit, Salmonella prevalence was 2.3%, reduced from a high of 23.1%. In conclusion, the study found low‐level Salmonella contamination in some GB broiler hatcheries, with certain hatcheries being more severely affected. Furthermore, it was shown that Salmonella typically is difficult to eradicate from contaminated hatcheries, but substantial reductions in prevalence are possible with improvements to biosecurity, cleaning and disinfection.

kisutch)

Human activities and resource exploitation led to a massive decline of wild salmonid populations, consequently, numerous conservation programs have been developed to supplement wild populations. However, many studies documented reduced fitness of hatchery-born relative to wild fish. Here, by using both RNA sequencing and Whole Genome Bisulfite Sequencing of hatchery and wild-born adult Coho salmon (Oncorhynchus kisutch) originating from two previously studied river systems, we show that early-life hatchery-rearing environment-induced significant and parallel gene expression differentiation is maintained until Coho come back to their natal river for reproduction. A total of 3,643 genes differentially expressed and 859 coexpressed genes were downregulated in parallel in hatchery-born fish from both rivers relative to their wild congeners. Among those genes, 26 displayed a significant relationship between gene expression and the median gene body methylation and 669 single CpGs displayed a significant correlation between methylation level and the associated gene expression. The link between methylation and gene expression was weak suggesting that DNA methylation is not the only player in mediating hatchery-related expression differences. Yet, significant gene expression differentiation was observed despite 18 months spent in a common environment (i.e., the sea). Finally, the differentiation is observed in parallel in two different river systems, highlighting the fact that early-life environment may account for at least some of the reduced fitness of the hatchery salmon in the wild. These results illustrate the relevance and importance of considering both epigenome and transcriptome to evaluate the costs and benefits of large-scale supplementation programs.

Genome-wide analysis of natural and restored eastern oyster populations reveals local adaptation and positive impacts of planting frequency and broodstock number

The release of captive-bred plants and animals has increased worldwide to augment declining species. However, insufficient attention has been given to understanding how neutral and adaptive genetic variation are partitioned within and among proximal natural populations, and the patterns and drivers of gene flow over small spatial scales, which can be important for restoration success. A seascape genomics approach was used to investigate population structure, local adaptation, and the extent to which environmental gradients influence genetic variation among natural and restored populations of Chesapeake Bay eastern oysters Crassostrea virginica. We also investigated the impact of hatchery practices on neutral genetic diversity of restored reefs and quantified the broader genetic impacts of large-scale hatchery-based bivalve restoration. Restored reefs showed similar levels of diversity as natural reefs, and striking relationships were found between planting frequency and broodstock numbers and genetic diversity metrics (effective population size and relatedness), suggesting that hatchery practices can have a major impact on diversity. Despite long-term restoration activities, haphazard historical translocations, and high dispersal potential of larvae that could homogenize allele frequencies among populations, moderate neutral population genetic structure was uncovered. Moreover, environmental factors, namely salinity, pH, and temperature, play a major role in the distribution of neutral and adaptive genetic variation. For marine invertebrates in heterogeneous seascapes, collecting broodstock from large populations experiencing similar environments to candidate sites may provide the most appropriate sources for restoration and ensure population resilience in the face of rapid environmental change. This is one of a few studies to demonstrate empirically that hatchery practices have a major impact on the retention of genetic diversity. Overall, these results contribute to the growing body of evidence for fine-scale genetic structure and local adaptation in broadcast-spawning marine species and provide novel information for the management of an important fisheries resource.

Temporal Study of Salmonella enterica Serovars Isolated from Fluff Samples from Ontario Poultry Hatcheries between 2009 and 2018

The objectives of this study were to determine the prevalence, temporal trends, seasonal patterns, and temporal clustering of Salmonella enterica isolated from fluff samples from poultry hatcheries in Ontario between 2009 and 2018. A scan statistic was used to identify clusters of common serovars and those of human health concern. A multi-level logistic regression model was used to identify factors (poultry commodity, year, season) associated with S. enterica presence. The period prevalence of S. enterica was 7.5% in broiler hatcheries, 1.6% in layer hatcheries, 7.6% in turkey hatcheries, 29.7% in waterfowl hatcheries, and 13.8% in game-bird hatcheries. An overall increasing trend in S. enterica prevalence was identified in waterfowl and game-bird hatcheries, while a decreasing trend was identified in broiler and turkey hatcheries. Overall, the most common S. enterica serovars were Kentucky, Enteritidis, Heidelberg, and Senftenberg. Salmonella enterica ser. Enteritidis was the most common serovar in waterfowl hatcheries. Temporal clusters were identified for all poultry commodities. Seasonal effects varied by commodity, with the highest odds of S. enterica occurring in the summer and fall. Our study offers information on the prevalence and temporality of S. enterica serovars that might guide prevention and control programs at the hatchery level.

Environment-driven reprogramming of gamete DNA methylation occurs during maturation and is transmitted intergenerationally in Atlantic Salmon

An epigenetic basis for transgenerational plasticity in animals is widely theorized, but convincing empirical support is limited by taxa-specific differences in the presence and role of epigenetic mechanisms. In teleost fishes, DNA methylation generally does not undergo extensive reprogramming and has been linked with environmentally induced intergenerational effects, but solely in the context of early life environmental differences. Using whole-genome bisulfite sequencing, we demonstrate that differential methylation of sperm occurs in response to captivity during the maturation of Atlantic Salmon (Salmo salar), a species of major economic and conservation significance. We show that adult captive exposure further induces differential methylation in an F1 generation that is associated with fitness-related phenotypic differences. Some genes targeted with differential methylation were consistent with genes differential methylated in other salmonid fishes experiencing early-life hatchery rearing, as well as genes under selection in domesticated species. Our results support a mechanism of transgenerational plasticity mediated by intergenerational inheritance of DNA methylation acquired late in life for salmon. To our knowledge, this is the first-time environmental variation experienced later in life has been directly demonstrated to influence gamete DNA methylation in fish.

Mortality patterns during the freshwater production phase of salmonids in Norway

Mortality in Norwegian salmonid aquaculture has a major influence on fish welfare and represents economic losses for producers. We reviewed the estimated monthly mortality for freshwater farms with Atlantic salmon and rainbow trout between 2011 and 2019. We built a regression model for mortality which included the variables year, weight group, season, region and farm. Additionally, we distributed questionnaires to farmers to gather information regarding potential causes of mortalities. The analysis of data for Atlantic salmon showed that median monthly mortality increased from 0.15% in 2011 (interquartile range [IQR]: 0.06-0.39) to 0.25% (IQR: 0.1-0.67) in 2019. Mortality was highest in the North (0.27%, IQR: 0.11-0.72) and lowest in the Southwest region (0.16%, IQR: 0.07-0.4). The season with highest mortality was summer (0.24%, IQR: 0.1-0.64), while winter had the lowest (0.12%, IQR: 0.05-0.35). The smallest fish (3-12 g) showed highest mortality (0.31%, IQR: 0.14-0.69) compared to heavier fish. Results from the questionnaire showed that infectious or non-infectious diseases were the most commonly reported causes of mortality. The mortality patterns described in this study identifies several important risk factors. Highlighting causal links is an important step to reducing mortality and improving welfare in the freshwater production phase of salmonids in Norway.

Factors Driving Bacterial Microbiota of Eggs from Commercial Hatcheries of European Seabass and Gilthead Seabream

A comprehensive understanding of how bacterial community abundance changes in fishes during their lifecycle and the role of the microbiota on health and production is still lacking. From this perspective, the egg bacterial communities of two commercially farmed species, the European seabass (Dicentrarchus labrax) and the gilthead seabream (Sparus aurata), from different aquaculture sites were compared, and the potential effect of broodstock water microbiota and disinfectants on the egg microbiota was evaluated. Moreover, 16S ribosomal RNA gene sequencing was used to profile the bacterial communities of the eggs and broodstock water from three commercial hatcheries. Proteobacteria were the most common and dominant phyla across the samples (49.7% on average). Vibrio sp. was the most highly represented genus (7.1%), followed by Glaciecola (4.8%), Pseudoalteromonas (4.4%), and Colwellia (4.2%), in eggs and water across the sites. Routinely used iodine-based disinfectants slightly reduced the eggs' bacterial load but did not significantly change their composition. Site, species, and type of sample (eggs or water) drove the microbial community structure and influenced microbiome functional profiles. The egg and seawater microbiome composition differed in abundance but shared similar functional profiles. The strong impact of site and species on egg bacterial communities indicates that disease management needs to be site-specific and highlights the need for species- and site-specific optimization of disinfection protocols.

Epigenomic modifications induced by hatchery rearing persist in germ line cells of adult salmon after their oceanic migration

Human activities induce direct or indirect selection pressure on natural population and may ultimately affect population's integrity. While numerous conservation programs aimed to minimize human-induced genomic variation, human-induced environmental variation may generate epigenomic variation potentially affecting fitness through phenotypic modifications. Major questions remain pertaining to how much epigenomic variation arises from environmental heterogeneity, whether this variation can persist throughout life, and whether it can be transmitted across generations. We performed whole genome bisulfite sequencing (WGBS) on the sperm of genetically indistinguishable hatchery and wild-born migrating adults of Coho salmon (Oncorhynchus kisutch) from two geographically distant rivers at different epigenome scales. Our results showed that coupling WGBS with fine-scale analyses (local and chromosomal) allows the detection of parallel early-life hatchery-induced epimarks that differentiate wild from hatchery-reared salmon. Four chromosomes and 183 differentially methylated regions (DMRs) displayed a significant signal of methylation differentiation between hatchery and wild-born Coho salmon. Moreover, those early-life epimarks persisted in germ line cells despite about 1.5 year spent in the ocean following release from hatchery, opening the possibility for transgenerational inheritance. Our results strengthen the hypothesis that epigenomic modifications environmentally induced during early-life development persist in germ cells of adults until reproduction, which could potentially impact their fitness.

Population structure of chum salmon and selection on the markers collected for stock identification

Genetic stock identification (GSI) is a major management tool of Pacific salmon (Oncorhynchus Spp.) that has provided rich genetic baseline data of allozymes, microsatellites, and single-nucleotide polymorphisms (SNPs) across the Pacific Rim. Here, we analyzed published data sets for adult chum salmon (Oncorhynchus keta), namely 10 microsatellites, 53 SNPs, and a mitochondrial DNA locus (mtDNA3, control region, and NADH-3 combined) in samples from 495 locations in the same distribution range (n = 61,813). TreeMix analysis of the microsatellite loci identified the greatest convergence toward Japanese/Korean populations and suggested two admixture events from Japan/Korea to Russia and the Alaskan Peninsula. The SNPs had been purposively collected from rapidly evolving genes to increase the power of GSI. The largest expected heterozygosity was observed in Japanese/Korean populations for microsatellites, whereas it was largest in Western Alaskan populations for SNPs, reflecting the SNP discovery process. A regression of SNP population structures on those of microsatellites indicated the selection of the SNP loci according to deviations from the predicted structures. Specifically, we matched the sampling locations of the SNPs with those of the microsatellites and performed regression analyses of SNP allele frequencies on a 2-dimensional scaling (MDS) of matched locations obtained from microsatellite pairwise F ST values. The MDS first axis indicated a latitudinal cline in American and Russian populations, whereas the second axis showed differentiation of Japanese/Korean populations. The top five outlier SNPs included mtDNA3, U502241 (unknown), GnRH373, ras1362, and TCP178, which were identified by principal component analysis. We summarized the functions of 53 nuclear genes surrounding SNPs and the mtDNA3 locus by referring to a gene database system and propose how they may influence the fitness of chum salmon.

Using model selection to choose a size-based condition index that is consistent with operational welfare indicators

Quantitative and qualitative measures of fish health and welfare are essential for management of both wild capture and aquaculture species. These measures include morphometric body condition indices, energetic condition and aquaculture operational welfare indicators (OWIs). Measures vary in ease of measurement (and may require destructive sampling), and it is critical to know how well they correlate with fish health and welfare so appropriate management decisions can be based on them. Lumpfish (Cyclopterus lumpus) is a new farming species that needs nondestructive OWIs to be developed and validated. In this study, we developed a C. lumpus fin damage score. Four different body condition indexes based on individual weight relative to either length-weight relationships or relative to other fish in its local environment were tested (using model selection) as predictors of individual fin damage. Results showed severity of fin damage was predicted by small size relative to the other individuals in the tank or cage. Body condition based on length-weight relationship was not found to predict fin damage, indicating that using established indices from fisheries or from other species would not predict welfare risks from fin damage. Implications are that especially in hatchery conditions grading will improve the condition index, and is expected to mitigate fin damage, but that low weight at length was not of use in predicting fin damage. Model selection to choose between a suite of possible indices proved powerful and should be considered in other applications where an easily measured index is needed to correlate with other health measures.

Polyculture of Juvenile Dog Conch Laevistrombus canarium Reveals High Potentiality in Integrated Multitrophic Aquaculture (IMTA)

Simple Summary

The dog conch (Laevistrombus canarium) is a marine gastropod mollusk widely distributed in the Indo-Pacific region. It is an economically crucial species; however, its population has been declining due to overfishing and overexploitation. Hence, we developed a novel polyculture and water-flow method for mass production of this species. Furthermore, the findings from this work also uncover the potentiality of L. canarium in integrated multitrophic aquaculture (IMTA) and its implication for aquaculture and resource restoration.

Abstract

Laevistrombus canarium, also known as dog conch, is a marine gastropod mollusk widely distributed in the Indo-Pacific region. It is an economically crucial species; however, its population has been declining due to overfishing and overexploitation. In this study, the suitable salinity for juvenile L. canarium was between 20 and 35‰. Diatoms and biological detritus by using flow-water from the fish pool were the most favorable diets for newly metamorphosed and 10 mm juveniles. In the polyculture experiment, L. canarium was cultured with whiteleg shrimp, tilapia, small abalone, purple sea urchin, and collector urchin. Better growth was found in all co-culture groups except with whiteleg shrimp. We also found that the polyculture system with or without substrates significantly affected the growth of juveniles. Additionally, we observed that water temperature was the most crucial factor for growth and survival; a water temperature of less than 10 °C might cause the death of L. canarium. We have proposed a novel polyculture and water-flow method for mass production of L. canarium and evaluated the feasibility and benefits of polyculture with other species. The findings from this work reveal the potentiality of L. canarium in integrated multitrophic aquaculture (IMTA) and its implication for aquaculture and resource restoration.

Infectious Bronchitis Hatchery Vaccination: Comparison between Traditional Spray Administration and a Newly Developed Gel Delivery System in Field Conditions

The control of infectious bronchitis (IB) is essential in intensive broiler production and is pursued through strict biosecurity and mass vaccination. Despite effective and routinely adopted, hatchery spray vaccination has been hypothesized to affect chicks’ body temperature and wellbeing. Recently, gel administration has been proposed as an alternative and proved feasible in experimental settings. In this study, IBV spray and gel vaccination methods were compared in field conditions. One hundred birds from the same hatch were enrolled in the study and vaccinated, half by spray and half by gel, with 793B and Mass vaccines. After vaccination, rectal temperature was measured and vaccine intake assessed. The two groups were housed for 35 days in separate pens and swabs and blood samples were collected at multiple time points for genotype-specific molecular analyses and serology, respectively. The temperature was significantly lower in spray-vaccinated chicks 10 min and an hour after administration. A similar trend in 793B titres was observed in both groups, while the Mass vaccine was detected later but persisted longer in gel-vaccinated chicks. No differences were observed in mean antibody titres. Compared to spray, gel administration appears equally effective and less impactful on body temperature, thus supporting its application for IBV vaccination.

Eggshell and Feed Microbiota Do Not Represent Major Sources of Gut Anaerobes for Chickens in Commercial Production

In this study, we addressed the origin of chicken gut microbiota in commercial production by a comparison of eggshell and feed microbiota with caecal microbiota of 7-day-old chickens, using microbiota analysis by 16S rRNA sequencing. In addition, we tested at which timepoint during prenatal or neonatal development it is possible to successfully administer probiotics. We found that eggshell microbiota was a combination of environmental and adult hen gut microbiota but was completely different from caecal microbiota of 7-day-old chicks. Similarly, we observed that the composition of feed microbiota was different from caecal microbiota. Neither eggshell nor feed acted as an important source of gut microbiota for the chickens in commercial production. Following the experimental administration of potential probiotics, we found that chickens can be colonised only when already hatched and active. Spraying of eggs with gut anaerobes during egg incubation or hatching itself did not result in effective chicken colonisation. Such conclusions should be considered when selecting and administering probiotics to chickens in hatcheries. Eggshells, feed or drinking water do not act as major sources of gut microbiota. Newly hatched chickens must be colonised from additional sources, such as air dust with spores of Clostridiales. The natural colonisation starts only when chickens are already hatched, as spraying of eggs or even chickens at the very beginning of the hatching process did not result in efficient colonisation.

A Review of the Nursery Culture of Mud Crabs, Genus Scylla: Current Progress and Future Directions

Simple Summary

Nursery culture knowledge is important for successful commercial seed production especially for mud crab, genus Scylla, a highly valued delicacy. The aim of this review paper is to summarise the status and information on the current nursery culture stage of the mud crab. Various aspects of mud crab hatchery described in this paper are expected to facilitate practitioners and lay people to easily understand a mud crab nursery. This review also provides guidelines for researchers in conducting future research and development on a mud crab nursery in order to increase the production of mud crab crablets for the farming industry.

Abstract

The nursery stages of mud crab, genus Scylla, proceed from the megalopa stage to crablet instar stages. We review the definition and several of the key stages in mud crab nursery activities. The practice of the direct stocking of megalopa into ponds is not recommended due to their sensitivity. Instead, nursery rearing is needed to grow-out mud crabs of a larger size before pond stocking. Individual nursery rearing results in a higher survival rate at the expense of growth and a more complicated maintenance process compared with communal rearing. The nursery of mud crabs can be done both indoors or outdoors with adequate shelter and feed required to obtain a good survival percentage and growth performance. Artemia nauplii are still irreplaceable as nursery feed, particularly at the megalopa stage, while the survival rate may be improved if live feed is combined with artificial feed such as microbound diet formulations. Water quality parameters, identical to those proposed in tiger shrimp cultures, can be implemented in mud crab rearing. The transportation of crablets between different locations can be done with or without water. The provision of monosex seeds from mud crab hatcheries is expected to become commonplace, increasing seed price and thus improving the income of farmers. Numerous aspects of a mud crab nursery including nutrition; feeding strategies; understanding their behaviour, i.e., cannibalism; control of environmental factors and practical rearing techniques still need further improvement.

Asymptomatic Carriage of C. botulinum Type D/C in Broiler Flocks as the Source of Contamination of a Massive Botulism Outbreak on a Dairy Cattle Farm

In winter 2018, a massive type D/C cattle botulism outbreak occurred on a mixed dairy and broiler farm in France. An investigation was conducted based on the hypothesis of asymptomatic carriage in poultry. We set out to identify the source of contamination of the dairy cattle and to monitor the contamination of broilers over time, including the hatchery delivering chicks to the farm. Environmental samples were collected on the farm during the cattle outbreak (n = 40), after the outbreak for three successive broiler flocks (n = 128), and once in the hatchery delivering the chicks (n = 58). These samples were analyzed using real-time PCR after an enrichment step to detect Clostridium botulinum type D/C. The results showed contamination in the manure from the broilers raised just before the onset of the cattle outbreak (5 + /5), as well as in some of the components of the cattle ration (3 + /17). This latter contamination is likely due to the use of the same tractor bucket to remove litter from the poultry house and to prepare the cattle ration on the same day. Contamination monitoring over several months revealed continuous asymptomatic carriage in the broilers (4 + /20 and 17 + /20 cloacal swabs in 2 successive flocks), a persistence of C. botulinum type D/C in the ventilation system of the poultry house (8 + /14), and contamination of the equipment coming from the hatchery used for delivering the chicks (3 + /18). Further investigations conducted in the hatchery demonstrated contamination in the hatchery by C. botulinum type D/C (6 + /58). Comparison of samples using a multilocus variable number tandem repeat analysis showed the same profile for samples collected on broilers, cattle and in the hatchery. This study highlighted the crucial role of the implementation of biosecurity measures in mixed farms to avoid cross-contamination between production units given the potential asymptomatic carriage of poultry. This study also revealed the contamination of the poultry hatchery. Further investigations are required to better understand the role of hatcheries in the epidemiology of animal botulism.

Field assessments of heart rate dynamics during spawning migration of wild and hatchery-reared Chinook salmon

During spawning, adult Pacific salmonids (Oncorhynchus spp.) complete challenging upriver migrations during which energy and oxygen delivery must be partitioned into activities such as locomotion, maturation and spawning behaviours under the constraints of an individual's cardiac capacity. To advance our understanding of cardiac function in free-swimming fishes, we implanted migrating adult Chinook salmon (Oncorhynchus tshawytscha) collected near the mouth of the Sydenham River, Ontario, with heart rate (f_H) biologgers that recorded f_H every 3 min until these semelparous fish expired on spawning grounds several days later. Fundamental aspects of cardiac function were quantified, including resting, routine and maximum f_H, as well as scope for f_H (maximum-resting f_H). Predictors of f_H were explored using generalized least-squares regression, including water temperature, discharge, fish size and fish origin (wild versus hatchery). Heart rate was positively correlated with water temperature, which aligned closely with daily and seasonal shifts. Wild fish had slower resting heart rates than hatchery fish, which led to significantly higher scope for f_H. Our findings suggest that wild salmon may have better cardiac capacity during migration than hatchery fish, potentially promoting migration success in wild fish. This article is part of the theme issue 'Measuring physiology in free-living animals (Part I)'.

Stress during Commercial Hatchery Processing Induces Long-Time Negative Cognitive Judgement Bias in Chickens

Simple Summary

Worldwide, billions of laying hen chicks are incubated, hatched and processed in industrial hatcheries every year. When exposed to stress, hormones are incorporated in the feathers of the birds. Here, we measured levels of the stress hormone corticosterone to investigate possible stress during the incubation. Further, animals can perceive their environment either in a positive (optimistic) or a negative (pessimistic) way. We investigated how the early hatchery experiences affects “optimism” and “pessimism”. Commercially hatched chicks were exposed to a positive cue, an aversive cue, and ambiguous cues, in order to evaluate the cognitive welfare state of the animals. These chicks were compared to a group of non-stressed animals. Commercially incubated chicks did not have elevated levels of feather corticosterone, which implies that the main part of the stress effects from the hatchery originates from the period around hatch. Latencies to approach ambiguous cues were longer for the stressed chicks, i.e., these showed a more pessimistic-like behaviour. We conclude that the main part of the stress effects in commercially hatched chicks originates in the period around hatch, and further, that these birds show lasting levels of increased pessimism. This strongly indicates a long-time poorer welfare state for the animals.

Abstract

Worldwide, billions of laying hen chicks are incubated and processed under highly industrialised circumstances every year, which, as we have previously shown, has long-lasting effects. Here, we measured corticosterone incorporated in down feathers to investigate possible stress during the incubation and showed that commercially incubated chicks did not have elevated levels of feather corticosterone, which implies that the main part of the stress effects from hatchery originates from the perinatal period and the handling immediately post-hatch. Further, we investigated how the early hatchery stress affects the chicks’ cognitive welfare state, i.e., “optimism” and “pessimism”. We exposed commercially hatched chickens to a positive cue, an aversive cue and ambiguous cues. The birds were tested at 1 and 10 w of age and the behaviour was compared with that of non-stressed chicks. Latencies to approach ambiguous cues were longer for the stressed chicks, both at 1 (p = 0.008) and at 10 (p = 0.020) weeks of age, i.e., these showed a more pessimistic-like behaviour. We conclude that the main part of the stress effects in commercially hatched chicks originates in the perinatal period, and further, that these birds show lasting levels of increased pessimism. This strongly indicates a long-time poorer welfare state for the animals.

Improving Survival of Juvenile Scalloped Spiny Lobster (Panulirus homarus) and Crucifix Crab (Charybdis feriatus) Using Shelter and Live Prey

Simple Summary

Fighting with each other is a major problem in lobster and crab aquaculture. Reducing the fighting behavior of lobsters and crabs can improve survival during the culturing process. Juvenile lobsters and crabs were both cultured under different shelters (seaweed and cotton filter) and live prey conditions. Groups with shelter and co-culturing with live prey showed a better survival rate for both juvenile lobsters and crabs. Although providing shelter is currently the main method for reducing agonistic behavior, it must be continually altered as the lobsters and crabs grow. Live prey can grow and attract lobsters and crabs to hunt them, and live prey can be supplemented at any time. They can also be used as an additional source of income during the harvest season.

Abstract

Cannibalism is a major problem in lobster and crab aquaculture. Reducing the aggressive characteristics of lobsters and crabs can improve survival during the culturing process. In this study, juvenile scalloped spiny lobsters (Panulirus homarus) and crucifix crabs (Charybdis feriatus) were both cultured under different shelter and live prey conditions. Groups with shelter (seaweed and cotton filter) showed a better survival rate than the control group (no shelter; p < 0.05) for both Pa. homarus and Char. feriatus. Co-culturing with live prey (Litopenaeus vannamei) significantly benefited the juveniles of Pa. homarus and visibly increased the survival of juvenile Char. feriatus. Although providing shelter is currently the main method for reducing agonistic behavior, it must be continually altered as the lobsters and crabs grow. Live prey can grow and attract lobsters and crabs to hunt them, and live prey can be supplemented at any time. They can also be used as an additional source of income during the harvest season.

Research Note: Application of an Escherichia coli spray challenge model for neonatal broiler chickens

Avian pathogenic Escherichia coli (E. coli) is an opportunistic pathogen often introduced to neonatal chicks during the hatching process. This commensal bacterium, particularly as a pioneer colonizer of the gastrointestinal tract, can have substantial implications in the rearing of poultry because of reduced flock performance. In order to mimic the effects of the natural bacterial bloom present during the hatch, a seeder challenge model was developed to expose neonatal chicks to virulent E. coli. On day 20 of embryogenesis, selected early hatched chicks (n = 18/hatcher) were briefly removed and sprayed challenged with saline (vehicle) or E. coli at 1 × 10⁷ colony-forming unit (CFU)/chick (exp 1) and 2.5 × 10⁷ CFU/chick (exp 2). These challenged chicks were returned to the hatcher to serve as seeders to transmit the pathogen to the indirect challenged or contact chicks (n = 195/hatcher). For two 7-d experiments, the efficacy of transmission was evaluated via enteric bacterial recovery, body weight gain (BWG), and mortality. For exp 1 and exp 2, significantly (P < 0.0001) more gram-negative bacteria were recovered from the seeder and contact gastrointestinal samples than the negative control samples on day of hatch. In addition, there was a reduction (P < 0.05) in 7-d BWG and significantly (P < 0.0001) higher mortality in the contact-challenged chicks than the negative control chicks in both exp 1 and exp 2. These data suggest that this challenge model could be used to evaluate different methods of controlling the bacterial bloom that occurs in the hatching environment.

The Occurrence of Antimicrobial-Resistant Salmonella enterica in Hatcheries and Dissemination in an Integrated Broiler Chicken Operation in Korea

Positive identification rates of Salmonella enterica in hatcheries and upstream breeder farms were 16.4% (36/220) and 3.0% (6/200), respectively. Among the Salmonella serovars identified in the hatcheries, S. enterica ser. Albany (17/36, 47.2%) was the most prevalent, followed by the serovars S. enterica ser. Montevideo (11/36, 30.6%) and S. enterica ser. Senftenberg (5/36, 13.9%), which were also predominant. Thirty-six isolates showed resistance to at least one antimicrobial tested, of which 52.8% (n = 19) were multidrug resistant (MDR). Thirty-three isolates (enrofloxacin, MIC ≥ 0.25) showed point mutations in the gyrA and parC genes. One isolate, S. enterica ser. Virchow, carrying the bla_CTX-M-15 gene from the breeder farm was ceftiofur resistant. Pulsed-field gel electrophoresis (PFGE) showed that 52.0% S. enterica ser. Montevideo and 29.6% S. enterica ser. Albany isolates sourced from the downstream of hatcheries along the broiler chicken supply chain carried the same PFGE types as those of the hatcheries. Thus, the hatcheries showed a high prevalence of Salmonella isolates with high antimicrobial resistance and no susceptible isolate. The AMR isolates from hatcheries originating from breeder farms could disseminate to the final retail market along the broiler chicken supply chain. The emergence of AMR Salmonella in hatcheries may be due to the horizontal spread of resistant isolates. Therefore, Salmonella control in hatcheries, particularly its horizontal transmission, is important.

Differential DNA methylation in somatic and sperm cells of hatchery vs wild (natural-origin) steelhead trout populations

Environmental factors such as nutrition, stress, and toxicants can influence epigenetic programming and phenotypes of a wide variety of species from plants to humans. The current study was designed to investigate the impacts of hatchery spawning and rearing on steelhead trout (Oncorhynchus mykiss) vs the wild fish on a molecular level. Additionally, epigenetic differences between feeding practices that allow slow growth (2 years) and fast growth (1 year) hatchery trout were investigated. The sperm and red blood cells (RBC) from adult male slow growth/maturation hatchery steelhead, fast growth/maturation hatchery steelhead, and wild (natural-origin) steelhead were collected for DNA preparation to investigate potential alterations in differential DNA methylation regions (DMRs) and genetic mutations, involving copy number variations (CNVs). The sperm and RBC DNA both had a large number of DMRs when comparing the hatchery vs wild steelhead trout populations. The DMRs were cell type specific with negligible overlap. Slow growth/maturation compared to fast growth/maturation steelhead also had a larger number of DMRs in the RBC samples. A number of the DMRs had associated genes that were correlated to various biological processes and pathologies. Observations demonstrate a major epigenetic programming difference between the hatchery and wild natural-origin fish populations, but negligible genetic differences. Therefore, hatchery conditions and growth/maturation rate can alter the epigenetic developmental programming of the steelhead trout. Interestingly, epigenetic alterations in the sperm allow for potential epigenetic transgenerational inheritance of phenotypic variation to future generations. The impacts of hatchery exposures are not only important to consider on the fish exposed, but also on future generations and evolutionary trajectory of fish in the river populations.

Effect of storage duration on egg quality, embryo mortality and hatchability in FUNAAB-ɑ chickens

Effect of extended storage on egg quality, embryo mortality and hatchability in FUNAAB-ɑ chickens was determined. Hatchable eggs (n = 288; weighing 53.2 ± 4.67 g) collected from a flock of FUNAAB-ɑ layer breeder hens aged 32 weeks were stored in egg tray with broad end up under 16 ± 1.5°C for either 0, 4, 8, 12, 16 or 20 d. Before incubation, eight eggs from each group were evaluated for internal and external quality traits. Remaining eggs were set in an incubator and transferred into hatcher on embryonic day 18. Data collected were subjected to one-way analysis of variance. Egg weight loss (EWL; p < .001), surface area (p < .001), yolk diameter (p < .001), inner and outer blastoderm diameters (p < .05) and dead in germ (DIG; p < .001) increased with storage duration while yolk height (p < .001), yolk index (p < .001), albumen weight (p < .05), albumen height (p < .05), albumen index (p < .01), Haugh's unit (HU; p < .05), fertility (p < .001), hatchability of set (HATCHS; p < .001) and fertile eggs (p < .05) decreased. Weight losses of 0, 1.2, 2.2, 3.4, 4.6 and 6.1% were recorded in egg stored for 0, 4, 8, 12, 16 and 20 days respectively. Eggs stored beyond 8 days exhibited higher DIG and lower HATCHS. Shell percentage in 4 days storage (11.4%) was lower (p < .05) than in 16 days storage (13.4%). Shell thickness was similar in eggs stored for 0 to 12 days, but 8 days storage (0.60 mm) had thinner (p < .01) shell than day 16 (0.71 mm) and day 20 (0.73 mm) storage. Internal quality unit (IQU) was higher (p < .05) in fresh eggs (180.4) than in 12 days (167.8) and 20 days (167.8) stored eggs. Extended storage of FUNAAB-ɑ eggs caused EWL, surface area shrinkage, lowered HU and IQU, loss of yolk and albumen quality, increased blastoderm diameters and DIG, and decreased egg fertility and HATCHS from day 8 forward. Storing FUNAAB-ɑ eggs beyond 8 days reduced quality parameters; therefore, other mitigating factors are recommended when storing beyond 8 days.

Aerosol delivery of synthetic DNA containing CpG motifs in broiler chicks at hatch under field conditions using a commercial-scale prototype nebulizer provided protection against lethal Escherichia coli septicemia

Synthetic DNA containing CpG motifs (CpG-ODN) are potent innate immune stimulators in neonatal and adult broiler chickens against bacterial septicemia. We have recently demonstrated that intrapulmonary (IPL) delivery of CpG-ODN as microdroplets under laboratory conditions can protect neonatal chickens against lethal Escherichia coli septicemia. The objectives of this study were to develop a commercial-scale poultry nebulizer (CSPN) that can deliver CpG-ODN as microdroplets in neonatal broiler chicks in the hatcheries and study the efficacy of CSPN in inducing immune-protective effects under different environmental conditions in 2 geographical locations in Canada. Three field experiments were conducted in commercial poultry hatcheries during different seasons of the year in Saskatchewan and British Columbia, Canada. Neonatal broiler chicks (n = 8,000/experiment) received CpG-ODN by the IPL route in the CSPN chamber for 30 min, and control chicks received distilled water (DW) for 30 min. Broiler chicks (CpG-ODN—240 chicks/experiment and DW—40 chicks/experiment) were randomly sampled from all locations of the CSPN after nebulization and challenged with a lethal dose of E. coli to examine the CpG-ODN nebulization induced protection. We found a significant level (P < 0.05) of protection in broiler chicks against E. coli challenge, suggesting that the newly built CSPN successfully delivered CpG-ODN via the IPL route. We found that when the CSPN was maintained at humidex 28°C or below and relative humidity (RH) between 40 and 60%, neonatal birds were significantly (P < 0.05) protected against E. coli septicemia after IPL delivery of CpG-ODN. By contrast, protection in chicks was adversely affected when the CSPN was maintained at the humidex of 29°C or higher and RH of 70%. Overall, the present study successfully built a CSPN for CpG-ODN delivery in chicks at the hatchery and revealed that the temperature, humidity, and humidex were critical parameters in CSPN for efficient delivery of CpG-ODN.

Impact of Rotten Eggs on Hatchery Performances: A Multicentric Study

Day-old chick quality is an essential element for the overall profitability of the broiler productive cycle and has been associated with the growth performance and feed conversion rate. An effect on the development of the immune system was also reported, which could likely account for reduced susceptibility to infectious diseases and improved animal welfare parameters. Besides direct cost reduction, lower antimicrobial use and improved animal welfare are crucial in the directive of European Union legislation and are at the forefront of customer choices. Several factors contribute to determining the chick quality. Breeder flocks genetics, health, and management affect the egg features, quality, and bacterial load. However, hatchery practices play a pivotal role, since adequate hygiene and handling are fundamental in reducing egg contamination and cross-contamination. The presence of rotten eggs is often regarded as a major risk, since the internal bacterial load can contaminate the needle used for in-ovo vaccination, the nearby eggs, and the whole incubator/hatching room when broken. In the present multicentric study, representative of 40 hatcheries located in 11 European countries, a remarkable impact of the rotten egg percentage on the hatchery productive parameters, representative of the hatchability, embryo mortality, and level of contamination, was demonstrated. Efficient rotten egg removal and the application of appropriate detection and removal tools should thus provide remarkable benefits for hatchery performance and indirectly for downstream poultry production.

Historical translocations and stocking alter the genetic structure of a Mediterranean lobster fishery

Stocking is often used to supplement wild populations that are overexploited or have collapsed, yet it is unclear how this affects the genetic diversity of marine invertebrate populations. During the 1970s, a lobster stock enhancement program was carried out around the island of Corsica in the Mediterranean using individuals translocated from the Atlantic coast of France. This included the release of thousands of hatchery-reared postlarval lobsters and several adult individuals, but no monitoring plan was established to assess whether these animals survived and recruited to the population. In this study, we sampled European lobster (Homarus gammarus) individuals caught around Corsica and tested whether they showed Atlantic ancestry. Due to a natural marked phylogeographic break between Atlantic and Mediterranean lobsters, we hypothesized that lobsters with dominant (>0.50) Atlantic ancestry were descended from historical stocking releases. Twenty Corsican lobsters were genotyped at 79 single nucleotide polymorphisms, and assignment analysis showed that the majority (13) had dominant Atlantic ancestry. This suggests that the hatchery stocking program carried out in Corsica during the 1970s, using individuals translocated from the Atlantic coast of France, has likely augmented local recruitment but at a cost of altering the genetic structure of the Corsican lobster population.

An escape theory model for directionally moving prey and an experimental test in juvenile Chinook salmon

Prey evaluate risk and make decisions based on the balance between the costs of predation and those of engaging in antipredator behaviour. Economic escape theory has been valuable in understanding the responses of stationary prey under predation risk; however, current models are not applicable for directionally moving prey.

Here we present an extension of existing escape theory that predicts how much predation risk is perceived by directionally moving prey. Perceived risk is measured by the extent antipredator behaviour causes a change in travel speed (the distance to a destination divided by the total time to reach that destination). Cryptic or cautious antipredator behaviour slows travel speed, while prey may also speed up to reduce predator–prey overlap. Next, we applied the sensitization hypothesis to our model, which predicts that prey with more predator experience should engage in more antipredator behaviour, which leads to a larger change in travel speed under predation risk. We then compared the qualitative predictions of our model to the results of a behavioural assay with juvenile Chinook salmon Oncorhynchus tshawytscha that varied in their past predator experience.

We timed salmon swimming downstream through a mesh enclosure in the river with and without predator cues present to measure their reaction to a predator. Hatchery salmon had the least predator experience, followed by wild salmon captured upstream (wild‐upstream) and wild‐salmon captured downstream (wild‐downstream).

Both wild salmon groups slowed down in response to predator cues, whereas hatchery salmon did not change travel speed. The magnitude of reaction to predator cues by salmon group followed the gradient of previous predator experience, supporting the sensitization hypothesis.

Moving animals are conspicuous and vulnerable to predators. Here we provide a novel conceptual framework for understanding how directionally moving prey perceive risk and make antipredator decisions. Our study extends the scope of economic escape theory and improves general understanding of non‐lethal effects of predators on moving prey.

Expert Elicitation to Estimate the Relative Risk of Food Safety Criteria Included in the Establishment-Based Risk Assessment Model for Canadian Hatcheries

The Canadian Food Inspection Agency is developing an Establishment-based Risk Assessment model for Hatcheries to allocate inspection resources according to the food safety risk associated with each hatchery falling under its jurisdiction. In a previous study, 29 factors contributing to the food safety risk of hatcheries were identified and grouped into three clusters (inherent risk, risk mitigation, and compliance) and assessment criteria were defined. The objective of the current study was to estimate the relative risk (RR) of these criteria. Two rounds of expert elicitations were conducted to allow 13 Canadian experts to estimate the RR of each criterion (n = 96) based on its potential impact on human health, with a specific focus on Salmonella spp. This process also aimed to estimate the maximum increase or decrease in the overall food safety risk of a hatchery when considering multiple criteria belonging to a specific cluster and to assess the risk attribution of Salmonella spp. at the hatchery and bird-type levels. Results showed that the respondent profile had no influence on the importance given to a majority of criteria. Uniformity of answers among experts improved from the first to the second round. Overall, 62.5%, 32.3%, and 5.2% of the criteria were attributed to an RR that was less than 2, between 2 and 3, and greater than 3, respectively. Mixing eggs from different supply flocks when placed into the same hatching unit, hatching multiple species, and importing eggs with unknown quality status were identified as having the highest contribution to a hatchery's inherent risk. Requiring information on the foodborne pathogen status of supplying flocks and the occurrence of regulatory enforcement actions were the most impactful risk mitigation and compliance factors, respectively. The median RR value assigned to each criterion and cluster will be used to build this new model.

Relative genomic impacts of translocation history, hatchery practices, and farm selection in Pacific oyster Crassostrea gigas throughout the Northern Hemisphere

Pacific oyster Crassostrea gigas, endemic to coastal Asia, has been translocated globally throughout the past century, resulting in self-sustaining introduced populations (naturalized). Oyster aquaculture industries in many parts of the world depend on commercially available seed (hatchery-farmed) or naturalized/wild oysters to move onto a farm (naturalized-farmed). It is therefore important to understand genetic variation among populations and farm types. Here, we genotype naturalized/wild populations from France, Japan, China, and most extensively in coastal British Columbia, Canada. We also genotype cultured populations from throughout the Northern Hemisphere to compare with naturalized populations. In total, 16,942 markers were identified using double-digest RAD-sequencing in 182 naturalized, 112 hatchery-farmed, and 72 naturalized-farmed oysters (n = 366). Consistent with previous studies, very low genetic differentiation was observed around Vancouver Island (mean F _ST = 0.0019) and low differentiation between countries in the Japan-Canada-France historical translocation lineage (France-Canada F _ST = 0.0024; Japan-Canada F _ST = 0.0060). Chinese populations were more differentiated (China-Japan F _ST = 0.0241). Hatchery-propagated populations had higher interindividual relatedness suggesting family structure. Within-population inbreeding was not detected on farms, but nucleotide diversity and polymorphism rate were lower in one farm population. Moving oysters from nature onto farms did not result in strong within-generation selection. Private alleles at substantial frequency were identified in several hatchery populations grown in BC, suggesting nonlocal origins. Tests of selection identified outlier loci consistent with selective differences associated with domestication, in some cases consistently identified in multiple farms. Top outlier candidates were nearby genes involved in calcium signaling and calmodulin activity. Implications of potential introgression from hatchery-farmed oysters depend on whether naturalized populations are valued as a locally adapted resource or as an introduced, invasive species. Given the value of the industry in BC and the challenges the industry faces (e.g., climate change, crop losses, biotic stressors), this remains an important question.

No good vaccination quality without good control: the positive impact of a hatchery vaccination service program

Vaccination is currently one of the most relevant control strategies in poultry production to reduce infectious disease–induced economic losses and decrease antimicrobial use. Besides intrinsic vaccine efficacy, a proper administration is fundamental to achieve an adequate coverage and protection. Hatchery vaccination is becoming the standard approach for routine vaccination because of administration easiness, the possibility to standardize and optimize the overall process, and the lower impact on animal welfare compared with different types of on-farm vaccination. However, a continuous maintenance, refinement, and training of the personnel are the key to success. In the present work, the effect of longitudinal hatchery audits, performed using a standardized, expert-developed questionnaire was evaluated in 169 hatcheries, located in 11 European countries, over a period of more than 4 yr. A dedicated tablet-based application was implemented for data collection, storage, and analysis, and the obtained scores were used in the evaluation, reporting to the hatchery management and improvement of critical points. A positive significant association was demonstrated between the variation in global and process-specific hatchery scores and the number of performed audits. Similarly, when the longitudinal nature of the data (i.e., multiple visits) was accounted for using linear mixed models, including the hatchery and country as random factors, a significant trend in performance improvement was observed visit after visit, although with certain differences based on the specific score and country. The present study demonstrates the benefits of an objective evaluation of hatchery performances through a standardized questionnaire, followed by the discussion on the major required actions. The widespread application of this approach should lead to a significant improvement in vaccine administration performances, with direct consequences on infectious disease occurrence and animal production performances, and indirectly on therapeutic and control-related costs.

Non-viable chicken embryos: an overlooked niche harbouring a significant source of multidrug resistant bacteria in the poultry production

Antimicrobial resistance (AMR) is a global issue, posing a grave threat to the public, animal, and environmental health. The AMR surveillance at the level of the hatchery is crucial to develop an AMR control strategy in the poultry industry. The objective of this study was to investigate the AMR profiles of bacteria isolated from yolk material of non-viable broiler chicken embryos at hatch from commercial hatcheries in western Canada. Antimicrobial susceptibility testing was done using the Kirby–Bauer disk diffusion method focusing on Escherichia coli (n = 170) and Enterococcus (n = 256) species, which are commonly used as indicators of AMR evolution. E. coli isolates were resistant to tetracycline, ampicillin, amoxycillin-clavulanic acid, triple sulpha, ceftiofur, gentamycin, and spectinomycin at the rate of 52.9%, 50.6%, 40.0% 31.8%, 29.4%, 29.4%, 21.8% respectively. Among those, 37.1% of E. coli were multidrug resistant. The descending order of antimicrobial resistance of E. faecalis was; tetracycline (61.9%), ceftiofur (46.2%), bacitracin (43.9%), erythromycin (31.4%) and tylosin (27.4%). Multidrug resistance was detected in 40.4% of E. faecalis isolates, and 85.7% of E. faecium isolates. To the best of our knowledge, this is the first report on AMR surveillance of non-viable chicken embryos. Overall, the present study revealed that non-viable chicken embryos, an overlooked niche for AMR surveillance, harbour multidrug-resistant E. coli, and enterococci that can be a substantial source of superbugs in the environment. Our data also highlight the urgency of including non-viable chicken embryos in AMR surveillance programme to understand AMR dissemination and its control.

Discovery and validation of candidate smoltification gene expression biomarkers across multiple species and ecotypes of Pacific salmonids

Early marine survival of juvenile salmon is intimately associated with their physiological condition during smoltification and ocean entry. Smoltification (parr-smolt transformation) is a developmental process that allows salmon to acquire seawater tolerance in preparation for marine living. Traditionally, this developmental process has been monitored using gill Na⁺/K⁺-ATPase (NKA) activity or plasma hormones, but gill gene expression offers the possibility of another method. Here, we describe the discovery of candidate genes from gill tissue for staging smoltification using comparisons of microarray studies with particular focus on the commonalities between anadromous Rainbow trout and Sockeye salmon datasets, as well as a literature comparison encompassing more species. A subset of 37 candidate genes mainly from the microarray analyses was used for TaqMan quantitative PCR assay design and their expression patterns were validated using gill samples from four groups, representing three species and two ecotypes: Coho salmon, Sockeye salmon, stream-type Chinook salmon and ocean-type Chinook salmon. The best smoltification biomarkers, as measured by consistent changes across these four groups, were genes involved in ion regulation, oxygen transport and immunity. Smoltification gene expression patterns (using the top 10 biomarkers) were confirmed by significant correlations with NKA activity and were associated with changes in body brightness, caudal fin darkness and caudal peduncle length. We incorporate gene expression patterns of pre-smolt, smolt and de-smolt trials from acute seawater transfers from a companion study to develop a preliminary seawater tolerance classification model for ocean-type Chinook salmon. This work demonstrates the potential of gene expression biomarkers to stage smoltification and classify juveniles as pre-smolt, smolt or de-smolt.

Identification and selection of food safety-related risk factors to be included in the Canadian Food Inspection Agency's Establishment-based Risk Assessment model for Hatcheries

Towards the continuous improvement of its inspection system, the Canadian Food Inspection Agency (CFIA) is developing an Establishment-based Risk Assessment model for Hatcheries to allocate inspection resources based on the food safety risk associated with the Canadian hatcheries falling under its jurisdiction. The objectives of the current study were to identify and select critical food safety-related risk factors that would be included in this model, with a main focus on Salmonella. A literature review was used to develop a comprehensive list of risk factors that could potentially contribute to the food safety risk attributed to Canadian hatcheries operating in all production streams (breeders, layers, broilers, turkeys, waterfowl and game birds). The development of this list used a selection process that was conducted according to the availability of data sources, the clarity of definition and the measurability of the selected risk factors. A panel of experts reviewed and adjusted the identified risk factors. A final list of 29 risk factors was generated; 20 originated from the scientific literature and nine from the expert panel. Risk factors were grouped in three clusters according to whether they pertained to the inherent risk (nine factors identified), risk mitigation (nine factors identified) or compliance of a hatchery with its preventive control plan and regulatory requirements (11 factors identified). Criteria for assessing each risk factor were defined based on common practices used in the Canadian hatchery industry. This comprehensive list of risk factors and criteria represents useful information to support the design and implementation of a Canadian risk assessment model for hatcheries, but could also be used by like-minded food safety authorities.

Genetic diversity and phenotypic variation within hatchery-produced oyster cohorts predict size and success in the field

The rapid growth of the aquaculture industry to meet global seafood demand offers both risks and opportunities for resource management and conservation. In particular, hatcheries hold promise for stock enhancement and restoration, yet cultivation practices may lead to enhanced variation between populations at the expense of variation within populations, with uncertain implications for performance and resilience. To date, few studies have assessed how production techniques impact genetic diversity and population structure, as well as resultant trait variation in and performance of cultivated offspring. We collaborated with a commercial hatchery to produce multiple cohorts of the eastern oyster (Crassostrea virginica) from field-collected broodstock using standard practices. We recorded key characteristics of the broodstock (male : female ratio, effective population size), quantified the genetic diversity of the resulting cohorts, and tested their trait variation and performance across multiple field sites and experimental conditions. Oyster cohorts produced under the same conditions in a single hatchery varied almost twofold in genetic diversity. In addition, cohort genetic diversity was a significant positive predictor of oyster performance traits, including initial size and survival in the field. Oyster cohorts produced in the hatchery had lower within-cohort genetic variation and higher among-cohort genetic structure than adults surveyed from the same source sites. These findings are consistent with "sweepstakes reproduction" in oysters, even when manually spawned. A readily measured characteristic of broodstock, the ratio of males to females, was positively correlated with within-cohort genetic diversity of the resulting offspring. Thus, this metric may offer a tractable way both to meet short-term production goals for seafood demand and to ensure the capacity of hatchery-produced stock to achieve conservation objectives, such as the recovery of self-sustaining wild populations.

Rearing environment affects spatial learning in juvenile Chinook salmon Oncorhynchus tshawytscha

We tested the prediction that a complex physical rearing environment would enhance short-term spatial memory as assessed by learning ability in a spatial navigation task in juvenile Chinook salmon Oncorhynchus tshawytscha. We reared fish in two low-density treatments, where fish were either in bare fiberglass tanks (bare) or in tanks with physical structure (complex). We also tested conventionally reared high-density hatchery fish to compare with these other experimental treatments. Our reason for including this third hatchery treatment is that the two low-density treatments, aside from the manipulation of structure, followed a rearing programme that is designed to produce fish with more wild-like characteristics. We tested individually marked fish for seven consecutive days and recorded movement and time to exit a testing maze. Stimulus conspecific fish outside the exit of the maze provided positive reinforcement for test fish. Fish from the bare treatment were less likely to exit the start box compared with fish in the complex and hatchery treatments. However, fish in the hatchery treatment were significantly more likely to exit the maze on their own compared with both the bare and complex treatments. Hatchery fish effectively learned the task as shown by a decrease in the number of mistakes over time, but the number of mistakes was significantly greater on the first day of trials. Increasing habitat complexity with structure may not necessarily promote spatial learning ability, but differences between hatchery and experimental treatments in rearing density and motivation to be near conspecifics likely led to observed behavioural differences.

Occupational Safety and Health in U.S. Aquaculture: A Review

Objectives: Aquaculture encompasses a variety of species in both freshwater and marine settings and can combine elements of agriculture and fishing, two recognized hazardous occupations. Efforts are underway to expand the aquaculture sector in the United States (U.S.), and should be informed by occupational safety and health (OSH) research. The objectives of this review paper are to: i) describe the U.S. aquaculture sector, ii) summarize statistics, peer-reviewed studies, and reports focused on U.S. aquaculture OSH, and iii) describe the policy landscape specific to U.S. aquaculture OSH.Methods: Literature searches employed databases and Internet search engines to identify relevant peer-reviewed articles, reports, and other resources. Due to the expected U.S. expansion of marine aquaculture and paucity of peer-reviewed U.S.-based OSH literature in this sector, additional searches for international research on marine aquaculture were conducted.Results: The U.S. Bureau of Labor Statistics estimated high rates of illness and injury among U.S. aquaculture workers in 2014 and 2015. Peer-reviewed literature on aquaculture OSH identified numerous physical, chemical, and biological OSH risks depending on production methods and settings. Significant policy gaps exist regarding U.S. aquaculture OSH surveillance, reporting, and regulation.Conclusion: This review identifies a critical need for research, surveillance, and best practices information, specific to the major types of aquaculture in the U.S., to augment and inform worker safety and health efforts in this expanding sector.