Wild Fish Research Articles

Marketing Strategy for "Anchovies Pizza" Processed Product in Munjungagung Village, Tegal Regency

Munjungagung Village is one of the villages bordering the northern coast of Java. Being located in a coastal area makes Munjungagung Village rich in marine fishery resource potential. The potential fishery resources are mostly generated by capture fisheries. In addition to fishery and marine resource potential, Munjungagung Village also has potential for marine tourism and a conservation area in the Jeruk Reef region. To support the fishery and marine sectors, Munjungagung Village has fishery infrastructure in the form of the PPP Larangan coastal fishery port, the PPI Larangan fish landing base, and the TPI Larangan fish auction site. As an area bordering the coastal region, Munjungagung Village also has a marine tourism attraction, namely the Larangan Beach. The catch of fish by the fishermen is very abundant, including anchovies. Anchovies are one of the quite potential fishery products in Munjungagung Village, Kramat District, Tegal Regency. However, in its utilization, fishermen only sell anchovies in wet form. Through community empowerment activities, mothers can diversify processed anchovy products by making a pizza called "Anchovies Pizza." One of the strategies that can be implemented in empowering the coastal community of Munjungagung Village is through the optimization of fishery products based on anchovies. Anchovy products can be optimized, one of which is by making "Anchovies Pizza." Through an economic-based approach for the coastal community, especially among mothers, it is hoped that the economic status of the coastal community can be improved.

Toward Sustainable Fisheries: Assessing Catch per Unit Effort, Retained Bycatch, and Discard Ratios in the Red Sea Shrimp Trawl Fishery of the Kingdom of Saudi Arabia

Shrimp trawl fishery is of significant importance in Saudi Arabia’s marine capture fishery sector. Al Qunfudhah and Jizan are the only ports along the southern Saudi Arabian coast of the Red Sea dedicated to shrimp fishing. This study evaluates the catch per unit effort (CPUE) of targeted shrimp species along with the associated retained bycatch and discard ratios across these two trawling locations. Using daily catch data from commercial shrimp trawlers specific to each port’s vessel type, this research provides the first comprehensive analysis of CPUE dynamics and fishing practices in these fishing grounds. The CPUE of target shrimps exhibited a wide range (0.01 kg h−1 to 13.08 kg h−1) with an overall mean of 1.37 ± 0.143 kg h−1. Penaeus semisulcatus emerged as the predominant species (mean CPUE: 3.77 ± 0.28 kg h−1), followed by Metapenaeus monoceros (mean CPUE: 0.1 ± 0.02 kg h−1). Significant differences in CPUE were observed among species, including P. semisulcatus, Penaeus hathor, and Penaeus pulchricaudatus, although CPUE differences between the two fishing grounds were minor, likely due to their proximity and similar environmental conditions. The bycatch analysis identified a total of 72 species across 28 families, with significant variation in the relative ratios. Sepiidae species constituted 31.8% of the total bycatch, followed by Portunidae species (24.8%). Discard patterns also varied, with Gerres oyena being the most commonly discarded species (mean discard ratio: 11.37% ± 1.89%), followed by Equulites klunzingeri (mean discard ratio: 8.76% ± 2.00%). While CPUE differences between Al Qunfudhah and Jizan were modest, this study highlights the need for expanded spatial and temporal coverage to enhance future analyses. These findings underscore the importance of integrated data for a comprehensive understanding of fishing effort and bycatch dynamics, supporting sustainable fisheries management in the Red Sea. By addressing bycatch and discard practices, this research contributes to efforts to mitigate ecological impacts and promote sustainable resource use in Saudi Arabia’s fisheries sector.

Monitoring Fish Bacterial Pathogens of Wild Fish Species From the South China Sea by Applying Next-Generation Sequencing on Gill Tissue.

The classic epidemiological triangle model of host-environment-pathogen is recently being reshaped into a tetrahedron, with the growing understanding of the importance of the microbiome in this array. The gills, being a gateway into the fish body, bearing an important role in fish homeostasis, host a complex microbiome that reflects the ambient water, while also showing resemblance to gut microbiome. Next-generation sequencing (NGS) and improvements in data analysis tools enable researchers to gather and analyse a lot more data than ever before, take a closer, more detailed look at microbiota, and gain a much better understanding of the biological processes at work in these complex relations. Here, 16S rRNA amplicons of bacterial DNA extracted from the gills of 36 asymptomatic specimens of three wild fish species from the South China Sea (Nemipterus japonicus, Alepes djebaba, and Saurida tumbil) were sequenced using NGS. Data analyses revealed the presence of 20 potentially pathogenic species, including several zoonotic agents. Gill microbiota exhibited host species-specificity, and expressed a significant difference between demersal and pelagic-amphidromous fish. It is suggested that this method be more widely implemented, in order to gain more insight on ocean ecosystems' health status, as well as fish stocks of commercial importance.

Single pass saltwater disinfection using low voltage electrolysis: Potential implications for aquaculture systems

Single pass saltwater disinfection using low voltage electrolysis: Potential implications for aquaculture systems

Streptococcus agalactiae Infection in Wild Trahira (Hoplias malabaricus) and Farmed Arapaima (Arapaima gigas) in Brazil: An Interspecies Transmission in Aquatic Environments Shared with Nile Tilapia (Oreochromis niloticus).

Streptococcus agalactiae is an important pathogen responsible for cases of high mortality in farmed and wild fish worldwide. In Brazil, this bacterium has been commonly associated with outbreaks in Nile tilapia farms, but other native fish species are also susceptible. Since floating cages are one of the most common culture systems used in the country, the close contact between farmed tilapia and native fish species presents a risk concerning the transmission of this pathogen. In this study, we characterized a mortality outbreak in free-living trahira and in farmed arapaima, as well as the genetic and antimicrobial susceptibility patterns of the isolates obtained. During the outbreaks, moribund fish were sampled and subjected to bacterial examination, after which the isolates were identified via MALDI-ToF analysis. Genotyping was evaluated using repetitive sequence-based PCR (REP-PCR) and multilocus sequence typing (MLST). Antimicrobial susceptibility was evaluated using disc diffusion assays. In addition, whole-genome analysis also was performed. S. agalactiae was identified in all diseased fish, all of which belonged to serotype Ib; however, trahira strains were classified as non-typeable lineages in the MLST assay, while arapaima strains were classified as ST260. These isolates were shown to be similar to the main genotype found in Nile tilapia in Brazil, using REP-PCR, MLST and phylogenomic analysis. The pathogenicity of the bacterium was confirmed by Koch's postulates for both fish species. The antimicrobial susceptibility assay showed variable results to the same antibiotics among the isolates, prompting four of the isolates to be classified as multidrug-resistant. This study represents the first report of a natural outbreak of Streptococcus agalactiae infection in wild trahira and farmed arapaima inhabiting the same aquatic environment as Nile tilapia.

PENGOLAHAN PRODUK DIVERSIFIKASI IKAN BAGI KELOMPOK WANITA NELAYAN MANDIRI DESA LAMUNDRE, KECAMATAN WATUBANGGA, KABUPATEN KOLAKA

Lamundre Village is one of the villages located in Watubangga District, Kolaka Regency which has promising marine natural resource potential, both in the form of aquaculture and capture fisheries. Various types of fish catch produced by the Lamundre Village Community include skipjack fish 30 tons/year and lure fish 70 tons/year. The catch is only dried and sold raw to the market. However, this potential can still be increased to increase the income of the Lamundre Village Community and increase the diversity of fishery products from the village. The Lamundre Village Independent Fishermen's Women's Group is a partner that operates in the fish processing sector. The main problem with partners is the low level of knowledge and skills of group members in processing fishery products. Therefore, it is very necessary to provide training and assistance to partners in processing fishery products. The fish processing products carried out are making fish balls and fish floss. Fish balls and fish floss are one of the fish processing activities that can increase the added value and shelf life of fish. The aim of this community service activity is to improve the skills and knowledge of the Independent Women Fishermen Group partners in processing fish independently into a product, namely fish balls and fish floss. This community service activity will be carried out in September 2024 in Lamundre Village, Watubangga District, Kolaka Regency. The activity method is carried out at several stages including the observation stage, preparation stage, training and mentoring stage, and evaluation stage. The result of this community service activity is an increase in partners' skills and knowledge in making fish balls and fish floss. Based on the results of the interview, the partner's skill level became 85% and the knowledge level increased 100% after the training. Partners are able to make fish balls and fish floss according to the materials provided. The fish balls and fish floss produced in this training activity do not smell or fishy, ​​this is because the process of making fish balls and fish floss complies with the quality standards for making fish balls and fish floss (SNI 7690.2013). This community service activity is able to improve the skills and knowledge of partners in making fish balls and fish floss.

RSNC-YOLO: A Deep-Learning-Based Method for Automatic Fine-Grained Tuna Recognition in Complex Environments

Tuna accounts for 20% of the output value of global marine capture fisheries, and it plays a crucial role in maintaining ecosystem stability, ensuring global food security, and supporting economic stability. However, improper management has led to significant overfishing, resulting in a sharp decline in tuna populations. For sustainable tuna fishing, it is essential to accurately identify the species of tuna caught and to count their numbers, as these data are the foundation for setting scientific catch quotas. The traditional manual identification method suffers from several limitations and is prone to errors during prolonged operations, especially due to factors like fatigue, high-intensity workloads, or adverse weather conditions, which ultimately compromise its accuracy. Furthermore, the lack of transparency in the manual process may lead to intentional underreporting, which undermines the integrity of fisheries’ data. In contrast, an intelligent, real-time identification system can reduce the need for human labor, assist in more accurate identification, and enhance transparency in fisheries’ management. This system not only provides reliable data for refined management but also enables fisheries’ authorities to dynamically adjust fishing strategies in real time, issue timely warnings when catch limits are approached or exceeded, and prevent overfishing, thus ultimately contributing to sustainable tuna management. In light of this need, this article proposes the RSNC-YOLO algorithm, an intelligent model designed for recognizing tuna in complex scenarios on fishing vessels. Based on YOLOv8s-seg, RSNC-YOLO integrates Reparameterized C3 (RepC3), Selective Channel Down-sampling (SCDown), a Normalization-based Attention Module (NAM), and C2f-DCNv3-DLKA modules. By utilizing a subset of images selected from the Fishnet Open Image Database, the model achieves a 2.7% improvement in mAP@0.5 and a 0.7% improvement in mAP@0.5:0.95. Additionally, the number of parameters is reduced by approximately 30%, and the model’s weight size is reduced by 9.6 MB, while maintaining an inference speed comparable to that of YOLOv8s-seg.

Optimism about Wild Fish Welfare

Optimism about Wild Fish Welfare

Implications of feed and seed costs in Asian seabass mariculture in the face of climate change

Mariculture, a sustainable and rapidly growing aquaculture sub-sector, meets global seafood demand while reducing strain on wild fish stocks and continues to expand worldwide. However, rising feed and seed costs pose significant challenges, overshadowing other farming expenses. Climate change exacerbates the profitability of sea cage farming, increasing volatility. The surge in fishmeal costs has a detrimental impact on operational expenditure (Opex) and continues to be a threat. Consequently, sea cage farming in India is at a critical juncture, needing a balance between technological advancements and stakeholders’ fiscal needs. In this context, this study examines peer-reviewed synthesized data by employing metrics to evaluate the implications of feed and seed costs in Asian Seabass (Lates calcarifer) sea cage farming over a 10-year horizon. The total sales revenue over the 10-year period was US $100,848, with a net profit of US $55,198.89. A 30% increase in feed and seed prices significantly altered the economic dynamics of the enterprise, leading to an 8.8 and 9.2% rise in the respective break-even points. There was also a significant effect on the Benefit–Cost Ratio (BCR), with a 30% increase in each factor resulting in a 10 and 18% change in the projected BCR, respectively. Therefore, the significance of feed and seed cost has been established, necessitating an inevitable shift from low-value fish to formulated feed adaption for sustainable mariculture development. The study suggests improvements to existing practices to maximize efficiency and minimize production costs.

Incorporating habitat use and life history to predict PCB residues in wild fish in an urban estuary

Owing to the heterogenous distribution of contaminated sediments in urban estuaries, contaminant residues, such as polychlorinated biphenyls (PCBs), in fish tissue can vary widely. To investigate the relationship between PCBs in fish tissue and heterogeneity of PCBs in sediment, we developed a geospatial Biota-Sediment Accumulation Factor (BSAF) model for an urban estuary. The model predicts whole fish total PCB residues at a scale of 0.1km2 by incorporating sediment chemistry, fish home range, and habitat type. The model predicted concentrations from across the estuary ranging from 0 to 161,456ng/g lipid. An estuary-wide (50+ km2) and a project-scale (1+ km2) field validation of the model demonstrated it produced values that were slightly skewed to low concentrations; performance improved with increased sediment data spatial coverage. We conclude this approach has potential for determining PCBs "hot spot," estimating remediation project footprints, and evaluating potential remediation improvements to the quality of a fishery.

Species-specific trends of plutonium, radiocesium, and potassium-40 levels in three fish species of the Yenisei river (Siberia, Russia)

The Yenisei is the largest river in the Northern Hemisphere receiving controlled radioactive discharges from nuclear facilities. The paper presents a comparative study of temporal trends of artificial radionuclides plutonium (239,240Pu) and radiocesium (137Cs), and a natural isotope of the essential macronutrient potassium (40K) in samples of three commercial fish species (Northern pike, Baikal grayling, and Siberian dace) occupying different positions in a trophic network in the Yenisei River (Siberia, Russia). Samples of fish were caught in the Yenisei in 2011-2020 during a period of significant changes in controlled radioactive releases into the river. The study has shown no increase in plutonium concentration in fish samples within two years after the upsurge in controlled Pu discharge into the river (2018-2020). Average activity concentration of 239,240Pu (mBq∙kg-1 d.w., range, mean±sd) in muscle of grayling (0.6-31.8, 10.9±8.6) was higher (p<0.01) than in muscle of dace (1.0-4.4, 2.4±1.2) and pike (1.1-11, 3.8±2.9). This can be attributed to the feeding of grayling on benthic invertebrates rich in Pu. The concentration of Pu tended to increase in muscle of pike with the increasing size of the fish. Average activity concentration of 137Cs (Bq∙kg-1 d.w., range, mean±sd) in muscle of pike, a piscivorous fish (1.8-23.4, 7.7±5.1), was significantly higher (p<0.001) than the average activity concentration of 137Cs in muscle of dace (0.7-5.7, 2.7±1.6) and grayling (1.3-7.2, 2.5±1.7). A similar effect was revealed for 40K. This can be attributed to biomagnification of 137Cs and 40K in food chains. The results will draw a baseline for assessment of dose-dependent ecological risks for wild fish itself and fish consumers, add field-based facts to the fundamental knowledge of behavior of artificial radionuclides in freshwater food chains, and suggests a hypothesis for consequent experimental studies.

Environmental Impact and Sustainable Practices in Aquaculture: A Comprehensive Review

Aquaculture is the fastest-growing food production sector, now contributing more to global fish biomass than capture fisheries. While much of this expansion has occurred over the past 50 years, it has been accompanied by numerous environmental challenges, including aquatic pollution driven by urbanization, industrialisation, harbour dredging, sand filling, pesticide runoff from agricultural activities, and land-use conflicts between aquaculture, industry, and tourism. These environmental concerns have heightened the focus on sustainability, particularly in relation to ecological preservation. This review explores the various types of waste generated by industries, households, and other establishments that are discharged into aquatic ecosystems, examining their potential impacts on aquaculture. In addition, it evaluates mitigation strategies aimed at reducing or eliminating these environmental threats. Increasing attention has been placed on raising awareness of environmental issues and adopting sustainable practices to minimise aquaculture's ecological footprint. While environmental degradation was not viewed as a critical issue in the early stages of the industry's development, it has now become a central concern across academic, governmental, industrial, and market sectors.

Brazil and regional fisheries management organizations - What is at stake?

Brazil and regional fisheries management organizations - What is at stake?

Gill-associated ammonia oxidizers are widespread in teleost fish.

Recent advances in sequencing methods have greatly expanded the knowledge of teleost-associated microorganisms. While fish-gut microbiomes are comparatively well studied, less attention has gone toward other, external organ-microbiome associations. Gills are particularly interesting to investigate due to their functions in gas exchange, osmoregulation, and nitrogen excretion. We recently discovered a branchial symbiosis between nitrogen-cycling bacteria and teleosts (zebrafish and carp), in which ammonia-oxidizing Nitrosomonas and denitrifying bacteria together convert toxic ammonia excreted by the fish into harmless dinitrogen (N2) gas. This symbiosis can function as a "natural biofilter" in fish gills and can potentially occur in all ammonotelic fish species, but it remains unknown how widespread this symbiosis is. In this study, we analyzed all publicly available gill microbiome data sets and checked for the presence of Nitrosomonas. We discovered that more than half of the described fish gill microbiomes contain 16S rRNA gene sequences of ammonia-oxidizing bacteria (AOB). The presence of gill-specific AOB was shown in both wild and aquacultured fish, as well as in marine and freshwater fish species. Based on these findings, we propose that ammonia oxidizers are widespread in teleost fish gills. These gill-associated AOB can significantly affect fish nitrogen excretion, and the widespread nature of this association suggests that the gill-associated AOB can have similar impacts on more fish species. Future research should address the contribution of these microorganisms to fish nitrogen metabolism and the fundamental characteristics of this novel symbiosis.IMPORTANCERecent advances in sequencing have increased our knowledge of teleost-associated microbiota, but the gill microbiome has received comparatively little attention. We recently discovered a consortium of nitrogen-cycling bacteria in the gills of common carp and zebrafish, which are able to convert (toxic) ammonia into harmless dinitrogen gas. These microorganisms thus function as a natural nitrogen biofilter. We analyzed all available gill microbiome data sets to determine how widespread gill-associated ammonia-oxidizing bacteria (AOB) are. More than half of the data sets contained AOB, representing both aquacultured and wild fish from freshwater and marine habitats. In total, 182 amplicon sequencing variants were obtained, of which 115 were found specifically in the gills and not the environmental microbiomes. As gill-associated AOB are apparently widespread in teleost fish, it is important to study their impact on host nitrogen excretion and the potential to reduce ammonia accumulation in (recirculating) aquaculture of relevant fish species.

Comparative genomic analysis reveals distinct virulence and resistance mechanisms in 21 bacterial fish pathogens

The rising bacterial infections threaten world aquaculture and wild fish populations, making it imperative to increase the understanding of the mechanisms of pathogenic virulence and resistance. This study applies comparative genomic analysis to 21 bacterial fish pathogens, using whole-genome sequences from public genomic resources and sophisticated bioinformatics tools for screening of virulence factors, mobile genetic elements, antibiotic resistance genes, anti-phage defense mechanisms and secretory systems. We have seen that the different pathogens depict a wide range of variability regarding virulence and resistance potential, which may be attributed to species-specific adaptation. Notably, Streptococcus agalactiae and Mycobacterium salmoniphilum were found to possess high offensive and defensive virulence potential, but at different regulative controls. We also found diverse secretion systems and intricate mechanisms for antibiotic resistance, which have provided very important insights into how pathogens adapt to their environments. By categorizing functional genes and finding anti-phage systems, our analysis has revealed new insights into the complex interactions among bacterial virulence, resistance, and host defense mechanisms. These findings not only shed new light on the bacterial pathogenesis process in aquaculture but also provide the bases for focused, therapeutically-based strategies and genomic surveillance programs able to improve disease management and sustainability in aquaculture environments.

Re-evaluation of certain aspects of the EFSA Scientific Opinion of April 2010 on risk assessment of parasites in fishery products, based on new scientific data. Part 2.

The objective of this opinion was to determine if any wild caught fish species, originating from specific fishing grounds and consumed in the EU/EFTA could be considered free of zoonotic parasites. In this Opinion the term 'fishery products' only refers to fresh finfish. As there are multiple fish species and numerous potential parasites, Anisakis sp. was used as an indicator of zoonotic parasites in marine areas. This parasite species is particularly suited as it is common in marine environments, capable of infecting multiple fish species and is the subject of the majority of published studies. On the rare occasion where Anisakis sp. data were not available, or all tests were negative, other parasites such as Contracaecum osculatum (s.l.) and/or Phocanema spp. were considered. In freshwater systems, all zoonotic parasites were investigated. Consumption, import and landing data were used to determine the most relevant fish species and, where possible, the source fishing areas were identified. The most commonly consumed wild caught fish species in the EU/EFTA include tuna, cod, Alaskan pollock, hake, herring, sardines, mackerel, trout and saithe. Although the majority of these fish are caught in the Atlantic Ocean, the Mediterranean and the Black Sea (37) as well as several areas in the Indian Ocean, imported fish may originate from any global fishing areas, with the exception of Antarctica. Based on the data, at least one zoonotic parasite has been reported in at least one fish species in each of the FAO marine fishing areas. Thus, due to relative low fish host specificity of the zoonotic parasites, the panel concluded that all wild caught fish species may be exposed to and infected with zoonotic parasites. The same applies to freshwater fishing areas, with many areas having multiple studies reporting the presence of zoonotic parasites in the wild caught fish species.

Seasonal and Interannual Salinity Variability on the Northeast U.S. Continental Shelf: Insights From Satellite Sea Surface Salinity and Implications for Stratification

AbstractThe Northeast U.S. continental shelf (NEUS) is a highly productive and economically important region that has undergone substantial changes in recent years. Warming exceeds the global average and several episodes of anomalously warm, sustained temperatures have had profound impacts on regional fisheries. A majority of recent research studies focused on the analysis of temperature; however, salinity can serve as a valuable tracer as well. With now more than a decade of remote‐sensing sea surface salinity data, we shed new light onto salinity variability in the region with focus on the Mid‐Atlantic Bight and assess its role for modulating stratification on the shelf using historical hydrographic data. Local river discharge drives decreasing salinities not only in spring and summer on the shelf but also in the Slope Sea. In spring, fresher water aids the build‐up of stratification and a low salinity surface layer extends to the shelf break above the pycnocline by the beginning of summer. An observed salinification in the fall is linked to offshore forcing over the slope associated with the presence of Warm Core Rings. Coherent low‐frequency salinity variability is found over the slope and shelf, highlighting that shelf conditions are significantly impacted by offshore variability. Conditions on the NEUS in 2015 were characterized by anomalously high salinities, associated with a northerly position of the Gulf Stream. A freshening between 2015 and 2021, is in agreement with increased river cumulative discharge as well as lower offshore salinities. Overall, salinity serves as a valuable additional tracer of these multi‐variate processes.

Parasite scars: the impact of salmon lice injury on sea trout populations.

Spillback effects of the parasitic salmon louse from fish farms to wild fish are a critical environmental concern for countries with wild salmon. The ectoparasitic louse causes significant physical and physiological damage to wild salmonids that probably have long-term impacts on individuals and population dynamics. However, empirical links between injuries and abundance of lice have not been established in the wild. This study establishes a strong association between dorsal fin injuries in wild sea trout (Salmo trutta) and infestation with salmon lice at a marine site in Norway. We further assessed the prevalence of such injuries on sea trout returning to spawning grounds from snorkelling observations in 16 rivers in Hardangerfjord, western Norway, from 2007 to 2021. The prevalence of injuries decreased with distance from the fjord outlet, from approximately 70% in middle and outer parts to approximately 10% in the inner parts. Additionally, a negative correlation was found between sea trout population size and the proportion of the population with dorsal fin damage. The results demonstrate that salmon lice inflict high levels of injury on significant portions of sea trout populations in areas with intensive fish farming, leading to poorer population status in affected populations.

Evidence of polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs) in wild fish species from the remote tropical marine environment, South China Sea

Polybrominated diphenyl ethers (PBDEs) and their alternatives (e.g., dechlorane plus (DPs) and decabromodiphenyl ethane (DBDPE)) are ubiquitous in various environmental media. However, limited data is available on these chemicals in edible fish species from the wide-open South China Sea (SCS). In the present study, ten legacy PBDEs and three substitutions (DBDPE and two DPs) were analyzed in 16 wild fish species sampled from the open SCS to investigate their spatial and species-specific variations. The results showed that the total concentrations of PBDEs, DBDPE, and DPs in fish samples were in the range of 1.69-47.6, not detected (nd) to 21.0, and nd to 3.80ng/g lipid weight (lw), respectively. BDEs 47, 209 and 100 were the dominant target PBDE congeners, representing 49.2%, 17.2% and 9.93% of the total PBDE concentrations, respectively. Higher concentrations of PBDEs, DBDPE, and DPs were found in fish species from the Wanshan Archipelago compared to those from the Mischief Reef and the Yongxing Island, suggesting the significant influence of anthropogenic activities. Species-specific differences in levels of PBDEs were observed, with the order of bathydemersal>demersal>pelagic≈reef-associated>benthopelagic species. The average fanti value of all fish samples was 0.68, suggesting commercial DP products as a contamination source. The levels of PBDEs, DPs, and DBDPE in fish samples were relatively low compared with those from other locations around the globe. Finally, the health risks concerning the ingestion of BDEs 47, 99, 153 and 209 via fish consumption collected from the SCS are negligible.

Metabolic rate and mitochondrial physiology adjustments in Arctic char (Salvelinus alpinus) during cyclic hypoxia.

Diel fluctuations of oxygen levels characterize cyclic hypoxia and pose a significant challenge to wild fish populations. Although recent research has been conducted on the effects of hypoxia and reoxygenation, mechanisms by which fish acclimatize to cyclic hypoxia remain unclear, especially in hypoxia-sensitive species. We hypothesized that acclimation to cyclic hypoxia requires a downregulation of aerobic metabolic rate and an upregulation of mitochondrial respiratory capacities to mitigate constraints on aerobic metabolism and the elevated risk of oxidative stress upon reoxygenation. We exposed Arctic char (Salvelinus alpinus) to 10days of cyclic hypoxia and measured their metabolic rate and mitochondrial physiology to determine how they cope with fluctuating oxygen concentrations. We measured oxygen consumption as a proxy of metabolic rate and observed that Arctic char defend their standard metabolic rate but decrease their routine metabolic rate during hypoxic phases, presumably through the repression of spontaneous swimming activities. At the mitochondrial level, acute cyclic hypoxia increases oxygen consumption without ADP (CI-LEAK) in the liver and heart. Respiration in the presence of ADP (OXPHOS) temporarily increases in the liver and decreases in the heart. Cytochrome c oxidase oxygen affinity also increases at day 3 in the liver. However, no change occurs in the brain, which is likely primarily preserved through preferential perfusion (albeit not measured in this study). Finally, in vivo measurements of reactive oxygen species revealed the absence of an oxidative burst in mitochondria in the cyclic hypoxia group. Our study shows that Arctic char acclimatize to cyclic hypoxia through organ-specific mitochondrial adjustments.