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Dissostichus eleginoides is a benthopelagic, carnivorous fish from circumpolar antarctic waters. It is a deep sea fish distributed up to 2500 m and reaching up to 200 kg, 2 m total length and over 50 years of lifespan. Although it is of commercial interest, with prices between 14-35 US$/kg, studies that allow its cultivation are scarce. D. eleginoides is considered to have a slow metabolism since it lives at low temperatures (2-11 °C) and high pressures (100-250 atmospheres). However, there are no records of their routine aerobic metabolism (or any in fact) and of their mass scaling in tanks captivity on the surface, being the aims of this study. Routine metabolism was measured in fish groups from 3 sizes, a) 2.31 ± 0.08 kg, b) 4.67 ± 0.06 kg and c) 8.97 ± 1.89 kg in two respirometry chambers allowing to perform closed respirometry. The average metabolic rate was 42.91 ± 0.48, 38.61 ± 2.64 and 35.35 ± 1.58 mg O2 kg-1 h-1 along fish sizes, with significant differences between sizes. The calculated scaling exponent was 0.85, similar to that reported for other cold-water fish species measured at the surface. Results show oxygen consumption rates, under surface pressure conditions, comparable to those of G. morhua and salmonids, which allows, preliminarily, to reject the initial hypothesis of a slow metabolism. Although the results are preliminary, they are the first to report on the routine metabolism of this species, making them relevant for future studies. Culture densities of 87.38, 57.77 and 64.92 kg m-3 were estimated for groups a, b and c presenting important advantages and new perspectives for the cultivation of D. eleginoides.

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Cassava dregs are a byproduct of processing cassava into tapioca. These ingredients possess a simplified carbohydrate structure after fermentation, which also serves as an essential carbon source to support bacterial growth. This research aims to examine the utilization of cassava dregs ferment (CDF) in accelerating biofloc formation for intensive whiteleg shrimp (Penaeus vannamei) culture. The research was carried out over 60 days in two HDPE-lined ponds. Treatment A (with CDF) was stocked with 200 shrimp/m2. Treatment B (without CDF) was stocked with 300 shrimp/m2. Treatment A accelerated the formation of biofloc at DOC 26, whereas the biofloc formation in Treatment B started at DOC 38. Weight growth of shrimp was similar to Treatment A, averaging 6.21 ±1.27 g as compared to 6.21 ±1.73 g in Treatment B. Survival rates were significantly different, with 99.1% in Treatment A and 75.3% in Treatment B. Feed conversion ratio and total biomass were 1.4/1,153 kg (Treatment A) and 1.49/1,263 kg (Treatment B). Based on these findings, it appears that CDF can be used as an alternative source of exogenous carbon in biofloc technology and improve the productivity of intensive whiteleg shrimp culture.

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This study reports the survival, hemocyte count and physiological response indicators of pearl oysters Pteria sterna and Pinctada mazatlanica seeded with allografts and xenografts for pearl culture. Two treatments of oysters receiving an allograft (both donor and host were Pt. sterna) or a xenograft (donor was Pt. sterna and host was P. mazatlanica) were compared against two control groups of unseeded oysters (allografts and xenografts) at 0, 0.5, 2, 24, and 72 h. While survival was not affected by any particular treatment, the number of circulating hemocytes was inversely proportional in both species; it did not vary in Pt. sterna after allografting from t0 to 2 h, but then gradually increased and reached a 4-fold peak at 72 h that differed significantly from its control group and t0. In P. mazatlanica, the hemocyte count increased significantly (3-fold) at 0.5 h after xenografting, but then gradually decreased to equal the value of its control group and t0 at 72 h. In Pt. sterna, glycogen and mucopolysaccharide indices decreased >50 % at 2 h and gradually returned to the initial value at 72 h. In contrast, neither index varied significantly in P. mazatlanica, indicating almost no use of energy stores to compensate for the effects of xenografting, as well as little mucus production due to tissue irritation, compared to allografting in Pt. sterna. The lipofuscin index followed a relatively stable pattern over time in treatments A and X and changes with respect to their control groups CA and CX were not significant up to 72 h. Our results indicate that P. mazatlanica responded significantly faster to xenografting and wound healing than Pt. sterna to allografting, and may be a viable host to receive Pt. sterna xenografts. This could contribute to improve pearl yield and quality in Pt. sterna.

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Local adaptations are important in evolution as they drive population divergence and preserve standing genetic diversity essential for resilience under climate change and human impacts. Protecting locally adapted populations is essential for aquaculture species. However, high larval connectivity and frequent translocations challenge this in Chilean blue mussel (Mytilus chilensis) aquaculture, a world-class industry in Chiloé Island. This study examined local adaptations in two ecologically distinct natural beds, Cochamó (northernmost inner sea of Chiloé) and Yaldad (southernmost tip), through a 91-day reciprocal transplant experiment and genomic evidence. Cochamó mussels grew faster in their native environment (0.015 g/day) than Yaldad (0.004 g/day), though growth declined upon transplantation. Mussels transplanted within and between beds displayed distinctive adaptive transcriptomic responses, with differentially expressed genes involved with immune function, osmoregulation, metabolism, and cellular balance. Additionally, 58 known outlier SNPs mapped over the species' genome sequence were linked with adaptive genes involved with osmoregulation, oxidative stress, and oxygen management, revealing selection-targeted specific genome regions. This study highlights how translocations affect the adaptive genomic response of M. chilensis and the impact of local environments in counterbalancing its genetic connectivity, concluding that the genomic differences in natural beds should be monitored and conserved for sustainable aquaculture practices.

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The accelerated growth of shrimp farming has led to an increased influx of organic and inorganic pollutants into water bodies, posing a threat to water quality, biodiversity, and human health. This study aimed to assess the impact of shrimp farming activities by analyzing the physical and geochemical variables of water and sediment associated with shrimp farming in Valença, Bahia. Samples were collected in triplicate, including controls, for a total of 10 samples analyzed. Results showed high levels of BOD and trace elements such as Al, Fe, and Mn, as well as low oxygen levels in the water compared to CONAMA Resolution 357/05. Principal Component Analysis and Pearson correlation revealed 38.2 % of significant correlations, mainly in water parameters like BOD and DO, influenced by seasonal variations and anthropogenic activities. Elements such as Al, Fe, and Mn were associated with Fe and Mn oxyhydroxides and aluminosilicates. No sediment concentrations exceeded CONAMA Resolution 454/12 limits; however, 48.6 % of the elements were linked to Fe and Mn oxyhydroxides and aluminosilicates. Although Co, Cu, Ni, and V correlated with Al, Fe, and Mn, they may also reflect anthropogenic inputs from shrimp farming via feed and fertilizers. Water bodies in Valença show a tendency to accumulate higher concentrations of elements in certain areas, which may not only be attributed to natural events but also to human activities like shrimp farming. This study represents a baseline for further analyses within similar enterprises and for conducting methodological studies related to aquatic life.

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The Peruvian grunt, Anisotremus scapularis, is beginning its domestication as a candidate species for marine aquaculture. The optimal management of fingerling production requires precise knowledge on early development. Herein, we report the methodology for capturing and conditioning wild specimens to find a viable broodstock. The speed of capture and transportation (about 30 min), the post capture preventive treatment (60 min with tetracycline), and the 6-days preventive antiparasitic treatment (29 ppm formalin) maximized survival and a rapid feeding adaptation. Progressive diets based on the copepod Emerita analoga, fish meal, pellets and processed feedstuff prompted the spontaneous broodstock spawning 7 months post-capture. The interannual spawning of this broodstock since September 2016 indicated the optimal control of its reproduction in captivity. The morphogenetic process of the embryo lasted 42 h at 18 °C compared to (31-41) h at 19 °C in northern Peruvian latitudes. The knowledge generated allowed us to work out broodstock and egg management protocols in southern Pacific latitudes (southern Peru and northern Chile). Such protocols would help to escalate larval and juvenile production and to alleviate fishing pressure on the overexploited Peruvian grunt population.

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Lactococcus petauri is an emerging pathogen causing piscine lactococcosis in various aquatic species. This disease has been increasingly reported as a cause of mortality in aquaculture. Due to the indiscriminate use of antimicrobials and to promote viable alternatives for their replacement, bioactive peptides with antimicrobial properties can be explored as tools against bacterial infections. Thus, the objective of this study was to identify the pathogen responsible for a mortality outbreak in cage-cultured Nile tilapia (Oreochromis niloticus), assess its pathogenicity, and evaluate the therapeutic efficacy of a commercial bioactive peptide and florfenicol against L. petauri. The bacterium was isolated from affected Nile tilapia exhibiting external and internal hemorrhages, ocular opacity, anorexia, and ascites. Koch's postulates were fulfilled by inoculating healthy fish with 3.6 × 107 CFU/mL of the bacterium, which induced clinical signs of generalized hemorrhage, ascites, and melanosis. Histopathological analysis revealed severe lesions in the liver, spleen, kidney, intestine, and heart, confirming the pathogen's high virulence in Nile tilapia. To evaluate potential treatments, fish were divided into six groups: G1) inoculated with L. petauri and treated with 15 mg/kg of bioactive peptide via gavage; G2) inoculated and treated with 15 mg/kg of florfenicol via gavage; G3) inoculated and treated with intraperitoneal injection of bioactive peptide (15 mg/kg); G4) inoculated and left untreated; G5) treated with PBS via gavage; and G6) inoculated with PBS. After 30 days, survival rates were G1: 36.85 %, G2: 16.79 %, G3: 26.44 %, and G4: 6.7 %. Significantly higher survival was observed in groups G1, G2, and G3 compared to G4. Moreover, bacterial persistence was only absent in groups G1 and G3. The study demonstrates the effectiveness of the bioactive peptide in treating L. petauri infections and preventing bacterial persistence in Nile tilapia, suggesting it is a viable alternative to traditional antimicrobials.

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This study evaluates the effectiveness of Total Reflection X-ray Fluorescence for multi-element analysis in mussels, focusing on sensitivity, precision, and detection limits. Additionally, it offers a cross-regional comparison of elemental composition in mussels from aquaculture farms in Italy, Spain, and Chile. TXRF, using suspensions of mussel samples, proved effective in detecting minor and trace elements, with recovery rates over 80% for Fe, Cu, Zn, As, and Sr. The research offers a chemical element comparison of Mytilus galloprovincialis and Mytilus chilensis mussels, revealing significant variation based on geographic origin. Correlation matrices demonstrated variable associations between elements, indicating that regional environmental conditions influence bioaccumulation. These findings deepen our understanding of how mussels accumulate elements in different environments. However, further research is needed to develop comprehensive elemental databases and to account for seasonal and temporal variations in mussels' elemental composition. This study may bring insight for food safety and public health monitoring.

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Piscine orthoreovirus (PRV) is a virus that is widely distributed among global aquaculture populations of salmonid species. The coho salmon (Oncorhynchus kisutch) is a species of increasing productive and economic importance in Chile. The presence of PRV has generated concern about its impact on the health and welfare of this species. The objective of this study was to comparatively describe the clinical manifestations, pathological changes, and pathogenesis associated with PRV infection in two different farms of farmed coho salmon in Chile through a prospective longitudinal descriptive observational study. The results demonstrated that PRV-1b and PRV-3a are independently associated with the same clinical and pathological presentation in farmed coho salmon. Microscopic pathology of the disease associated with PRV-1b and PRV-3a was primarily characterized by degenerative and inflammatory findings in the heart and liver. Hematological and blood biochemistry biomarkers in fish exhibited alterations, manifesting as hemolytic anemia and prehepatic jaundice likely due to indirect hyperbilirubinemia. Pathogenesis of infection associated with both PRV-1b and PRV-3a would indicate a specific tropism for erythrocytes and cardiomyocytes of the spongy myocardium. It is noteworthy that despite a notable reduction in viral load of both PRV subgroups in tissues, the frequency of macroscopic lesions increased during the final phase of the study. In conclusion, the results indicate a strong correlation between infection by both PRV subgroups and the proposed orthoreoviral cardiomyopathy and hemolytic jaundice (OCHJ) disease. Further research on the pathogenesis and surveillance of PRV-1b and PRV-3a subgroups is pivotal to develop effective strategies for the control of OCHJ in farmed coho salmon.

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The study aimed to investigate the influence of different microalgae used in green water culture on the intestinal morphology of the seahorse Hippocampus reidi during the first 15 days of life. Four treatments were tested in triplicate, consisting of two microalgae (Tisochrysis lutea-ISO and Chaetoceros muelleri-CHO), used either individually (TISO and TCHO) or combined (TIC 1:1) in larval rearing water, and a treatment without microalgae (TWM). Larvae (6.68 ± 0.55 mm) were fed copepods (Parvocalanus crassirrostris; 2 ind mL-1) and rotifers (Brachionus rotundiformis; 8 ind mL-1) from the first to the seventh day, and from the eighth day onwards, with Artemia sp. nauplii (2 ind mL-1). For the analysis of intestinal histomorphometry, histological analysis of the tissue was performed on day 0 (initial) and after 7 and 15 days. The results demonstrate a significant increase in weight and weight gain of the larvae on the 15th day in the treatments with the addition of the microalgae T. lutea, whether alone or combination with other microalgae, compared to TWM. In relation the intestinal histomorphometry of larvae, the ANCOVA revealed that, on the 7th and 15th day, only the treatments with microalgae significantly affected the surface area of the intestinal villi. The intestinal histomorphometry of larvae from TISO showed higher values of villus height (85.29 ± 1.23 µm2) compared to TWM (69.42 ± 2.82 µm2) and TCHO (76.92 ± 2.23 µm2) (P < 0.05) but did not show significant differences compared to TIC (80.127 ± 2.08 µm2), which reflected on the villi surface area. Therefore, larvae from TISO (3603.43 ± 151.31 µm2) and TIC (3550.29 ± 120.99 µm2) showed significantly higher values of this parameter compared to TWM (3026.79 ± 147.64 µm2) and TCHO (3069.09 ± 126.18 µm2) (P < 0.05). In conclusion, the protocol for H. reidi larvae rearing in a green water system with the addition of the microalgae T. lutea resulted in an increase in the intestinal absorption area, resulting in improved performance of the larvae.

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Live cultures, including Nannochloropsis oculata and Brachionus plicatilis, are essential in aquaculture due to its economic and nutritional value for commercial fish species. Pathogens and probiotics can be introduced to aquaculture systems by live feed, with variations in abundance influenced by environmental physicochemical parameters. To investigate this, amplicon sequencing of the V3-V4 region of the 16S rRNA was conducted using Illumina MiSeq to elucidate bacterial abundances and their variations in response to changes in physicochemical parameters in live feed cultures. Results revealed that pathogens like, Tenacibaculum, predominantly found in rotifer cultures, was inhibited under dissolved oxygen levels of 6.87-8.19 mg/L and pH levels of 8.63-9.23. Winogradskyella, mainly present on day 1 of the microalgae culture, thrived under these same conditions. Potential probiotics were also analyzed. Phaeodactylibacter, primarily found on day 1 of microalgae cultures, was favored by dissolved oxygen levels of 7.11-7.68 mg/L and pH levels of 8.63-9.23 but was inhibited by nitrite levels of 0.46-0.5 mg/L. Overall, dissolved oxygen was the key parameter modulating microbial diversity. This study shows that optimizing environmental parameters can enhance culture health by promoting probiotics and reducing harmful bacteria.

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Bivalve mollusks may be affected by numerous infectious diseases, which cause high mortality rates and economic burdens for producers. Another challenge for bivalve aquaculture is the protection of farms from human contamination, such as sewage and stormwater discharges. Ilha Grande Bay (IGB), located in Rio de Janeiro state, is the largest Brazilian producer of scallops (Nodipecten nodosus). This region has recently suffered a mass mortality of mollusks, and several environmental contaminants have been reported in the area. To contribute to the elucidation of scallop collapse and better characterize the human impacts, this study assessed the circulation of mollusk (Ostreid herpesvirus-1 [OsHV-1]) and human (mastadenovirus [HAdV] and norovirus GII) viral pathogens in waters and animals produced at IGB. Neither water nor animals were positive for OsHV-1. However, of the 7 points analyzed, 5 points showed contamination by HAdV or norovirus. HAdV and norovirus were detected in 5.5 and 6.9% of the analyzed water samples, respectively, in concentrations ranging from 2.39 × 103 to 1 × 105 genome copies/L. One scallop sample was positive for norovirus (4.5%). These results demonstrate human contamination in the region, presenting a risk of consumer contamination, and a non-association between OsHV-1 and the mass mortality described in scallops.

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BACKGROUND: Aquaculture and salmon farming can cause environmental problems due to the pollution of the surrounding waters with nutrients, solid wastes and chemicals, such as antibiotics, which are used for disease control in the aquaculture facilities. Increasing antibiotic resistance in human-impacted environments, such as coastal waters with aquaculture activity, is linked to the widespread use of antibiotics, even at sub-lethal concentrations. In Chile, the world's second largest producer of salmon, aquaculture is considered the primary source of antibiotics residues in the coastal waters of northern Patagonia. Here, we evaluated whether the structure and diversity of marine bacterial community, the richness of antibiotic resistance bacteria and the frequency of antibiotic resistance genes increase in communities from the surface seawater of an area with salmon farming activities, in comparison with communities from an area without major anthropogenic disturbance. RESULTS: The taxonomic structure of bacterial community was significantly different between areas with and without aquaculture production. Growth of the culturable fraction under controlled laboratory conditions showed that, in comparison with the undisturbed area, the bacterial community from salmon farms displayed a higher frequency of colonies resistant to the antibiotics used by the salmon industry. A higher adaptation to antibiotics was revealed by a greater proportion of multi-resistant bacteria isolated from the surface seawater of the salmon farming area. Furthermore, metagenomics data revealed a significant higher abundance of antibiotic resistant genes conferring resistance to 11 antibiotic families in the community from salmon farms, indicating that the proportion of bacteria carrying the resistance determinants was overall higher in salmon farms than in the undisturbed site. CONCLUSIONS: Our results revealed an association between bacterial communities and antibiotic resistance from surface seawater of a coastal area of Chile. Although the total bacterial community may appear comparable between sites, the cultivation technique allowed to expose a higher prevalence of antibiotic resistant bacteria in the salmon farming area. Moreover, we demonstrated that metagenomics (culture-independent) and phenotypic (culture-dependent) methods are complementary to evaluate the bacterial communities' risk for antibiotic resistance, and that a human-influenced environment (such as salmon farms) can potentiate bacteria to adapt to environmental stresses, such as antibiotics.

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The wild and farm-raised ornamental fish trade is an industry that generates substantial economic profits worldwide. We report the parasitic fauna of imported marine and freshwater ornamental fish from ten aquarium wholesaler shops from two important localities in Mexico: Morelos Market in Mexico City and Merida in the state of Yucatan. Between February 2016 and March 2020, a total of 631 fish were examined for parasites, of which 66 species belong to 19 families of marine ornamental fish and 22 species from 9 families of freshwater ornamental fish. Twelve parasite species were recovered in marine fish belonging to three taxa: 7 Digenea, 3 Monogenea and 2 Nematoda. In freshwater fish, four parasite species belonging to four taxa were found: Protozoa, Digenea, Nematoda and Cestoda. Infection of individual fish species by specific parasites ranged from 0.20 to 4.55 %. The monogeneans Neobenedenia girellae and Pseudempleurosoma haywardi were the most prevalent parasites. Spearman's rank correlation test showed a significant association between various aquarium biosecurity practices, such as the absence of a quarantine area, low water exchange rates, lack of prophylactic treatments, inadequate removal of dead fish, and insufficient disinfection of water and equipment with the prevalence of N. girellae and P. haywardi. This knowledge can aid in the development of effective management strategies to promote the health of ornamental fish populations imported, minimize disease outbreaks and ensure the sustainable growth of this industry in Mexico.

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Climate change is altering not only the mean conditions of marine environments, but also their temporal variability and predictability. As these alterations are not uniform across seascapes, their biological effects are expected to accentuate intra-specific differences in the adaptive capacity (e.g., plasticity and evolutionary potential) of natural populations. To test this theoretical framework, we assessed the phenotypic and genetic profiles of mussel from three study sites across a multi-driver heterogeneous environmental mosaic in Chilean Patagonia. Our study reveals that temporal variability, predictability, and exposure to extreme events (low pH/low salinity), collectively, can modulate the plasticity and optimal conditions of mussels. Despite these phenotypic differences, we observed low genetic differentiation, likely resulting from significant gene flow induced by aquaculture, ultimately diminishing variation among individuals from different geographic areas. Our findings underscore how variability and predictability are essential factors shaping phenotypic diversity, even at small spatial scales. Balancing these factors could enhance species resilience and ecological success, crucial for biodiversity conservation amidst climate change.

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OBJECTIVES: The two oyster species studied hold considerable economic importance for artisanal harvest (Crassostrea rhizophorae) and aquaculture (Crassostrea gasar). Their draft genomes will play an important role in the application of genomic methods such as RNAseq, population-based genomic scans aiming at addressing expression responses to pollution stress, adaptation to salinity and temperature variation, and will also permit investigating the genetic bases and enable marker-assisted selection of economically important traits like shell and mantle coloration and resistance to temperature and disease. DATA DESCRIPTION: The draft assembly size of Crassostrea gasar is 506 Mbp, and of Crassostrea rhizophorae is 584 Mbp with scaffolds N50 of 11,3 Mbp and 4,9 Mbp, respectively. The general masked bases by RepeatMasker in both genomes were highly similar using different datasets. The masked bases varied from 9.41% in C. gasar to 10.05% in C. rhizophorae and 42.85% in C. gasar to 44.44% in C. rhizophorae using Dfam and RepeatModeler datasets, respectively. Functional annotation with eggNog resulted in 34,693 annotated proteins in C. rhizophorae and 26,328 in C. gasar. BUSCO analysis shows that almost 99% of genes (5,295) are complete in relation to the mollusk orthologous genes dataset (mollusca_odb10).

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Countries in the Americas play a vital role in global livestock and aquaculture production. With international trade of livestock and aquaculture products becoming an important source of income for countries, there has been an increased interest in using animal health economics for advocacy and allocation of resources. This article discusses the development of a new Collaborating Centre for the Economics of Animal Health and the applications of the Global Burden of Animal Diseases (GBADs) framework in the Americas region. Incentives for the increased use of economics in animal health decision-making and examples from the Americas region are examined. The article then discusses the newly formed World Organisation for Animal Health Collaborating Centre in the Americas region. Finally, it reviews two ongoing case studies that are implementing the GBADs framework in Peru and the United States of America.

Les pays des Amériques jouent un rôle crucial dans la production mondiale d'animaux d'élevage, qu'il s'agisse d'espèces terrestres ou aquatiques. Le commerce international des produits issus de l'élevage et de l'aquaculture étant désormais une source importante de revenus pour les pays, la possibilité d'utiliser les concepts de l'économie de la santé animale à des fins de plaidoyer et d'allocation des ressources suscite un intérêt croissant. Les auteurs abordent la désignation d'un nouveau Centre collaborateur pour l'économie de la santé animale ainsi que les applications du programme " Impact mondial des maladies animales " (GBADs) dans la région des Amériques. Ils examinent les avantages d'une meilleure prise en compte de l'économie dans les prises de décision en matière de santé animale, illustrés par quelques exemples concrets relevés dans la région. Ils décrivent ensuite la création du nouveau Centre collaborateur de l'Organisation mondiale de la santé animale dans la région des Amériques. Enfin, ils présentent deux études de cas menées actuellement concernant la mise en oeuvre du programme GBADs respectivement au Pérou et aux Etats-Unis d'Amérique.

Los países de las Américas desempeñan un papel fundamental en la producción ganadera y acuícola mundial. Dado que el comercio internacional de productos ganaderos y acuícolas se ha convertido en una importante fuente de ingresos para los países, el interés por utilizar la economía de la sanidad animal en favor de la promoción y la asignación de recursos ha ido en aumento. En este artículo se analiza la creación de un nuevo Centro colaborador para la economía de la sanidad animal y las aplicaciones del marco del impacto global de las enfermedades animales (GBADs) en la región de las Américas. Se examinan los incentivos para un mayor uso de la economía en la toma de decisiones sobre sanidad animal, así como ejemplos de la región. A continuación, en el artículo se presenta el recién creado Centro colaborador de la Organización Mundial de Sanidad Animal en la región de las Américas. Por último, se examinan dos estudios de casos en los que se está poniendo en práctica el marco del GBADs en Perú y los Estados Unidos de América.

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Piaractus brachypomus (Pacú) is the main native fish species cultivated in Peru and holds great potential for growth in aquaculture from the Peruvian Amazon. Between October 2021 and January 2022 in two fish producing farms in the Amazon region of San Martín in Peru, P. brachypomus individuals were examined for parasite evaluation. A total of 6366 monogeneans were isolated from the gills of 30 fish, revealing a prevalence of 100%, with an abundance and mean intensity of 212 parasites per fish. Monogeneans were morphologically identified as Mymarothecium viatorum and Anacanthorus penilabiatus. The genetic divergence in the 28S rDNA gene found among A. penilabiatus sequences was 0.1% and among Anacanthorus spp. it ranged from 0.9% to 7.5%. The genetic divergence found among the M. viatorum sequences was 0.3%. These finding represents the first molecular data of M. viatorum and A. penilabiatus in Peru using the 28S rDNA gene of these monogeneans. The new sequences obtained will contribute to future studies on the phylogenetic relationships among dactylogyrids. However, further research with a broader range of host-parasite samples and additional genetic markers is needed to clarify these relationships and provide stronger support for the phylogenetic positions.

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The adoption of standardized metrics and indicators of antimicrobial use (AMU) in the food animal industry is essential for the success of programs aimed at promoting the responsible and judicious use of antimicrobials in this activity. The objective of this study was to introduce the use of standardized AMU metrics and indicators to quantify the use of florfenicol and oxytetracycline in the Chilean salmon industry, and in this way evaluate the feasibility of their use given the type of health and production information currently managed by the National Fisheries and Aquaculture Service (SERNAPESCA), the Chilean agency responsible for regulating aquaculture in Chile. The data available from SERNAPESCA allowed the construction and evaluation of the most data-demanding AMU metrics and indicators. Consequently, the use of florfenicol and oxytetracycline administered by oral and parenteral routes was quantified using the treatment incidence based on both animal defined daily dose (TIDDDvet) and animal used daily dose (TIUDDA). To that end, the study included information from 1320 closed production cycles from farms rearing Atlantic salmon, coho salmon and rainbow trout that were active between January 2017 and December 2021. By applying standardized AMU metrics and indicators, we were able to determine that the median of TIDDDvet for florfenicol was 75.1 (80 % range, 20.0-158.0) DDDvet per ton-year at risk for oral procedures and 0.36 (80 % range, 0.07-1.19) DDDvet per ton-year at risk for parenteral procedures. For oxytetracycline, the median TIDDDvet was 3.09 (80 % range, 0.74-42.8) and 0.47 (80 % range, 0.09-1.68) DDDvet per ton-year at risk for oral and parenteral procedures, respectively. The median TIUDDA for treatments with florfenicol was 45.6 (80 % range, 10.9-96.5) UDDA per ton-year at risk for oral treatments and 0.28 (80 % range, 0.05-0.80) UDDA per ton-year at risk for parenteral treatments. For oxytetracycline, the median TIUDDA was 2.63 (80 % range, 0.61-28.2) UDDA per ton-year at risk for oral treatments and 0.41 (80 % range, 0.08-1.29) UDDA per ton-year at risk for parenteral treatments. This study demonstrates that it is feasible to move from traditional AMU metrics and indicators to standardized ones in the Chilean salmon industry. This is possible because the competent authority requires salmon farms to report detailed health and production information at a high frequency. The use of standardized AMU metrics and indicators can help the authority to have a more comprehensive view of the antimicrobial use in the Chilean salmon industry.

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The use of pyrethroids in aquaculture has been an important component of achieving a thriving salmon farming industry in Chile. While the residual presence of such substances is known to depend on environmental conditions, most ecotoxicological studies to date have not considered environmental context. Here, we conducted oceanographic monitoring combined with experiments aiming to estimate the effects of two pyrethroids on the feeding rates of larvae of farmed mussels, Mytilus chilensis. In additional experiments, mussel spats were exposed to both pyrethroids, but under contrasting temperature/pH so as to mimic winter and summer conditions. Experiments mimicking spring conditions revealed that both pyrethroid substances affected the feeding of mussel larvae as a function of concentration. Conversely, significant impact of pyrethroids on adults were not observed with regard to temperature and pH, but a significant impact of low temperature/low pH condition on ingestion rates was confirmed. Given the current status of increasing ocean acidification, the results of this study are expected to provide useful information with regard to achieving sustainable mussel aquaculture, especially considering both activities occur in similar geographic areas, and the expansion of salmon farming areas is ongoing in Chile.