Wild-caught Fish Research Articles

Heavy Metal Biomonitoring in Cultured Rainbow Trout of the Black Sea and Risk Estimations on Its Consumption.

In recent years, the growing importance of fish species obtained through aquaculture, coupled with a decline in wild-caught fish, has raised concerns about the potential accumulation of pollutants in these fish. This work aimed to analyze the amounts of elements in trout cultured mainly between Sinop and Samsun shores at the south of the Black Sea and marketed in Sinop fish markets. The comparison of these values with national and internationally accepted regulations was conducted, and evaluation of health risks for consumers was performed. Oncorhynchus mykiss samples were bought in April, May, and June of 2022 and 2023. The heavy metal concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). Fish tissues were wet digested in Teflon vessels. The outcomes were contrasted with established regulatory limits for heavy metals in fish. Fortunately, the metal concentrations detected in the fillets were found to be below the permissible levels set by regulations, indicating that the fish were not significantly contaminated. Furthermore, the estimated daily intake (EDI) and target hazard quotient (THQ) values, which are utilized to evaluate the possible health risks connected with heavy metal exposure, were calculated. It was reassuring to find that both EDI and THQ values were below the acceptable thresholds, suggesting that the consumption of O. mykiss is not likely to pose a threat to human health. To preserve seafood safety and safeguard public health, however, constant monitoring of fish metal levels is necessary.

Food waste in high income countries: Spanish fish value chain as a case study

High-income countries are expected to be more efficient in preventing food waste (FW) along the value chain compared to low- and middle-income countries, with the exception of the consumer stage. However, it is still a problem to be solved, especially in fresh food due to its perishability and in livestock due to its nutritional and economic impact. Following this prioritization, wild-caught fish was defined as a weak point for FW in the food system of high-income countries. Spain was used as a representative country for high- countries' fish sector due to its international trading and production/consumption ratios. The length of food supply chains (FSCs) was identified as a factor influencing FW incidence, highlighting short FSCs as a model for reducing FW. Regulations have been targeted as drivers but also as prevention and mitigation factors for FW. Technological tools and innovations already available in the market can be used to reduce FW, but there are still barriers affecting their adoption.

Hydrolysis Optimization of Thraustochytrid (Heterotrophic Protist) Biomass for the Production of a New and Sustainable Ingredient for the Aquafeed Industry

Thraustochytrids biomass, rich in docosahexaenoic acid (DHA), could be a sustainable ingredient for the aquafeed industry. However, its production cost renders it less competitive than fishmeal and fish oil from wild-caught fish. This study proposes optimizing the hydrolysis conditions of thraustochytrid biomass to generate an ingredient with improved properties thanks to the production of peptides with different biological activities. The improved nutritional value of the biomass could justify its use to decrease the amount of wild-caught fish in aquafeed, which would enhance the sustainability of fish aquaculture. First, two commercial proteases, Papain and Alcalase 2.4L, were compared for their capacity to hydrolyze the biomass. The best degree of hydrolysis (19 ± 1%) was obtained with Alcalase 2.4L, which was then used for the optimization of the pH, enzyme concentration and reaction time using response surface methodology. The results showed that the highest concentration of peptides and DHA in the aqueous phase was obtained with a pH, enzyme concentration and reaction time of 7.5, 2.7% and 205 min, respectively. If thraustochytrid hydrolysates prove to improve fish fitness, this mild and free-solvent process protocol could be used to produce a sustainable ingredient for aquafeed.

Can farmed fish match the preference of consumers accustomed to wild fish? Evidence from Central Malawi

The existing capacity of capture fisheries in Malawi is operating at its maximum potential, unable to meet the growing demand for fish. To address this issue, expanding the output of the aquaculture sector appears to be the only viable solution for augmenting fish supply and consumption. However, consumers in Malawi prefer fish sourced from their natural habitats, often considering farmed fish as inferior. Fortunately, advancements in breeding techniques and aquaculture management have led to improved quality of farmed fish. In this study, our objective was to identify and compare the desired characteristics and marketing preferences of fresh tilapia among consumers in Malawi with those of aquaculture-produced fish. This comparison aimed to determine if farmed fish align with consumer expectations. A conjoint experiment was conducted in Lilongwe city targeting 280 fresh tilapia fish consumers. Preferences and associated willingness to pay were modeled using rank-ordered logit regression. The findings indicate that consumers favor smaller-sized fish (around 130 g), a size that is currently achievable through aquaculture practices. Interestingly, consumers displayed less enthusiasm for a pricing model based solely on weight. Notably, although consumers maintain a belief that wild-caught fish is superior to farmed fish, they indicated a willingness to pay for farmed products. The current technology and practices allow aquaculture farms to produce fish within the preferred size range, which presents an opportunity for sector expansion. However, achieving this potential requires effective marketing strategies to shift cultural perceptions that currently hinder the acceptance of farmed fish.

An Updated Review of the Marine Ornamental Fish Trade in the European Union

Wild-caught fish from coral reefs, one of the most threatened ecosystems on the planet, continue to supply the marine aquarium trade. Despite customs and veterinary checks during imports, comprehensive data on this global industry remain scarce. This study provides consolidated data on the largest import market by value, the European Union (EU): a 24-million-euro annual trade value, detailing the main exporting and importing countries, as well as the species and families of the 26 million specimens imported between 2014 and 2021. A watchlist alert system based on the number of specimens traded, import trends, and vulnerability index according to FishBase and the IUCN Red List conservation status is presented, providing key information on which species should require closer scrutiny by authorities. While the European TRAde Control and Expert System (TRACES) electronically monitors the movement of live animals to respond quickly to biosecurity risks, one-third of marine ornamental fish imported lack species-level information. With minor adjustments, TRACES holds the potential to significantly enhance data granularity and the monitoring of wildlife trade, with marine ornamental fish being an interesting case study to validate this approach.

Bystanders to a Public Health Crisis

Per- and polyfluoroalkyl substances (PFAS) are devastating our food systems and our health. Due to widespread use, these synthetic, long-lasting chemicals, are omnipresent at dangerous levels in our envi-ronment and our homes. Recent studies link even small exposure to PFAS to a host of adverse health outcomes, including cancer, autoim-mune diseases, thyroid disease, liver damage, childhood obesity, infer-tility, and birth defects. Food consumption is a primary route of PFAS exposure. PFAS mi-grate from water, soil, fertilizers, pesticides, and compost into virtually every plant, fish, animal, and animal product, and ultimately (in the greatest concentration) into the consumer. In addition, food pro-cessing equipment, disposable dishes, and containers leach dangerous levels of these chemicals into processed food products, further infusing our every meal with PFAS. Consequently, it is no surprise everything from chocolate cake and microwave popcorn to free range eggs, wildcaught fish, organic milk, and organic kale can harbor staggering quantities of these toxic substances. Despite the widespread presence of these substances and strong sci-entific evidence of their harmful impact on humans, federal regulation of PFAS in food is currently nonexistent. At least fifteen agencies have a mandate to ensure the safety of our food. More is not always better. In the case of regulatory agencies, it can lead to fragmented demand for attention, diffusion of responsibilities, and bureaucratic bystander apathy. This story has played out time and again with other toxic con-taminants like polychlorinated biphenyls (PCBs) and pesticides and is playing out yet again with PFAS. Despite our country’s devastating experience with past contaminants and the unprecedented scientific progress of our time, the federal response to new food safety threats has only become more sluggish and inadequate. This article lays a pathway for change, taking the issue of PFAS food contamination as a case study for the broader dysfunction in the food safety regulatory system. Part II reviews the history of federal food regulation and explores the role that each federal actor in the field plays in ensuring the safety of the food supply. Part III provides back-ground on the chemical and toxicological profile of PFAS and their widespread presence in the environment in general and the food sup-ply in particular. Part IV examines possible approaches to more effec-tive regulation of environmental contaminants in food and proposes a readily available but currently overlooked mechanism for combatting the current public health crisis of PFAS in food. Lastly, Part V cata-logues the expected benefits of the solution and addresses anticipated skepticism. It concludes that the proposed approach can effectively protect consumers from PFAS in food today, while simultaneously gar-nering much needed data to usher in a more permanent solution in the future.

The reproduction performance of catching Planiliza subviridis (Teleostei: Mugilidae) in different moon periods from Jepara Coast, Central Java, Indonesia

Abstract. Yudiati E, Yuniarti T, Trianto A, Arifin Z, Ruliaty L, Soleh M, Naryaningsih A, Suryati. 2024. The reproduction performance of catching Planiliza subviridis (Teleostei: Mugilidae) in different moon periods from Jepara Coast, Central Java, Indonesia. Biodiversitas 25: 1823-1830. Mullets (Planiliza subviridis Valenciennes 1836) are highly promising species for aquaculture development. Information on the reproductive performance of wild-caught fish is crucial for enhancing mullet production. This study aimed to assess the gonadal maturity level of female mullets captured during full and new moon phases. Sampling using lift nets was conducted from June to July 2023, comprising 104 individuals, 51 during the new moon and 53 during a full moon. Fish caught during different moon phases were measured for gonad maturation level (GML) and morphometric parameters (body weight, total length, head length, body width, and head width), assessed for gonad somatic index (GSI), fecundity, and egg diameter. Over 50% of individuals were at GML III during dark moon phases, while during bright moon phases, only 10-15% were at GML III; GSI ranged from 0.6-15%. The fecundity of GML I and II females was higher during the full moon (220,212-395,000 eggs per individual) compared to the new moon, while GML III females during dark moon phases ranged from 225,000-250,000 eggs. Mullets exhibit increased reproductive output during the new moon phase and engage in synchronous spawning during moonlight cycles. Therefore, prospects for mullet culture appear promising, with cultivation and domestication suggested during new moon periods.

Optimising seafood nutritional value and environmental sustainability in aquaculture through a novel integrated modelling tool applicable to IMTA and monoculture

Aquaculture policies that decrease the reliance on wild-caught fish and promote integrated multi-trophic aquaculture (IMTA) both aim to lessen the environmental footprint but often overlook economic-environmental trade-offs and neglect social, health, and broad-scale sustainability considerations. Here we present a new bio-physical model (FYNE) that bridges some of these gaps, by linking farm operational choices, such as feed choices and farm siting, with the nutritional value of the farm-gate seafood products and the resulting environmental eutrophication footprint at the farm level. The FYNE model operates both in conditions of monoculture or of IMTA production, and estimates feed composition effects on growth and omega-3 fatty acid content of Atlantic salmon (Salmo salar) and blue mussel (Mytilus edulis), and nitrogen and carbon concentrations, the latter being a measure of the environmental eutrophication footprint of the farm. The model here developed integrates for the first time (i) an ecosystem model of an IMTA and (ii) a fatty acid dynamics model, with new models for salmon feed digestibility and mussel ingestion. The outputs span (i) production analysis for simulation of biomass; (ii) farm mass-balance analysis on deposition analysis and environmental eutrophication footprint; and (iii) product nutritional quality, in terms of fatty acid content. An application of the model to an IMTA farm in Scotland (UK) demonstrates how fatty acid and environmental changes can be modelled in tandem and could be used to support the industry to optimize the nutritional value of cultured species and manage aquatic environmental eutrophication footprint at farm level, informing feed and siting decisions. The model effectively predicts changes in omega-3 fatty acids, particularly DHA and EPA, in response to variations in feed composition. Notably, our results confirm that salmon waste has limited influence on mussel growth due to the spatial separation within the IMTA system, which emphasizes the need for strategic siting to enhance system productivity through effective waste recycling. Additionally, results show that while increasing fishmeal in diets enhances environmental outcomes, it reduces levels of critical fatty acids like DHA and EPA, underscoring the need for balanced feed formulations. The method developed in this study described a novel integrated model (FYNE) that extend previous modelling work by incorporating the influence of farmed species feed composition on fatty acid dynamics as well as the farming environmental factors.

Diet Shifts Alter the Activity and Distribution of Digestive Enzymes in an Herbivorous Fish

The digestive tract is central to the function of an animal since it assimilates nutrients from the diet. Digestion itself is a chemical process and digestive enzymes are the digestive catalysts. Thus, we measured amylase, maltase, N-acetyl-b-d-glucosaminidase, lipase, trypsin, aminopeptidase, and alkaline phosphatase activities along the digestive tract of the marine herbivorous fish, Cebidichthys violaceus. We did this for wild-caught individuals of this species, and compared those to individuals fed carnivore, omnivore, and herbivore diets in the laboratory for six months. In laboratory fish, the enzymatic activities were generally lower compared to wild-caught fish. In wild caught fish, a strong anterior-to-posterior gradient of amylase activity was observed along the gut and this pattern largely disappeared in the lab-fed fish. N-acetyl-β-D-glucosaminidase (NAGase), which breaks down chitin products, showed an increase in activity in the distal intestines of the lab-fed fish, which is not observed in wild fish. The NAGase activity of the herbivorous fishes correlate with the bacterial species Paroccus sp., which is a known NAGase producer, and one of the dominant microbes in the distal intestines of the lab-fed fish. The role of this enzyme, however, remains unclear since the lab diets did not contain large amounts of chitin. These enzymatic differences tell us how much fish can modify their enzymatic activity to align with their diet. In summary, the findings show that C. violaceous can endure different degrees of protein and carbohydrate levels, within limits. Their digestive system clearly changed in response to more protein in the diet, along with a microbiome that had more potential pathogens. Live algal diets would may be the most suitable for this herbivorous fish based on the totality of gathered data from the lab. American Physiological Society Fellowship UCI Microbiome Initiative Grant. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The use of fishery and aquaculture by-products with Nannochloropsis sp. allows total dietary replacement of wild-caught fishmeal, fish oil and soy protein in European sea bass juveniles

Five experimental diets (CTRL, 50FMFO, 50FMFO-50MIC, 0FMFO-50MIC, 0FMFO-100MIC) were formulated to replace wild-caught fishmeal (FM), wild-caught fish oil (FO) and soy protein using fisheries, aquaculture by-products (BP) and microalgae (MIC). Fifty European sea bass juveniles were distributed in 15 tanks (initial body weight 46.66 ± 0.04 g) and reared in a recirculating aquaculture system for 88 days. Temperature, salinity, oxygen and photoperiod were kept constant throughout the experiment (22 ± 0.5 °C, 25 g L−1 and 8.0 ± 1.0 mg L−1, 12:12 light/dark, respectively). Growth, feed intake (FI), proximal composition, nutritional index, apparent digestibility, somatometric indexes, blood plasma biochemistry and digestive enzyme activity were evaluated. Also, gut microbiota composition was assessed through next-generation sequencing. Results showed that growth performance and feed digestibility were not affected by FM, FO and soy replacement using BP and MIC. Dietary replacement of 100% FM and FO with circular substitutes and 50% replacement of soymeal with microalgae increased the activity of alkaline phosphatase and chymotrypsin. Moreover, the inclusion of BP and MIC had positive effects on the gut microbiota richness and abundance. In conclusion, the utilization of BP and MIC represents a valuable alternative to FM and FO as well as soy protein in feed for European sea bass juveniles.

Selenium-mercury interactions and relationship to aquatic toxicity: A review.

A review of the literature pertaining to selenium-mercury (Se/Hg) interactions in aquatic species was performed to provide insight into the mechanisms allowing for the reported changes in bioaccumulation and toxicity that have been observed when the two elements occur at elevated concentrations. Selenium (Se) has been shown to protect against mercury (Hg) toxicity in all animal models evaluated (fish, birds, mammals, and plants). To explore the interaction between the two elements, data are presented on concentrations of both elements in wild-caught fish at numerous locations. The data show that most fish have Se/Hg ratios >1.0. The importance of this ratio has been reported, with suggestions that the protective interaction is due in large part to the formation of HgSe. Data show that when the Se/Hg molar ratio is <1.0 in the diet of fish and animals, Hg toxicity will be expressed, provided that the Hg concentration is sufficiently high. This toxicity is likely the result of Se deficiency leading to an excess of reactive oxygen species. Laboratory fish toxicity studies reviewed show that Se toxicity can be reduced or eliminated when Hg is added to the diet in moderate amounts. Field studies have shown reduced accumulation of Hg when Se concentrations are increased. When Hg in the diet is significantly elevated (usually >10 µg/g), toxicity is expressed regardless of the Se present. Likewise, amelioration of Se toxicity by Hg occurs over a limited range. Tissue thresholds for Se toxicity have been derived primarily from studies where fish eggs were extracted from wild fish and embryo deformities were observed; however, the amount of Hg in the fish or ovaries was not considered, which could lead to uncertainty in the toxicity threshold. It is recommended that both elements be measured and evaluated when performing risk assessments and setting water quality criteria. Integr Environ Assess Manag 2024;00:1-11. © 2024 SETAC.

In silico biomarker analysis of the adverse effects of perfluorooctane sulfonate (PFOS) exposure on the metabolic physiology of embryo-larval zebrafish

Perfluorooctane sulfonate (PFOS) is a ubiquitous pollutant in global aquatic ecosystems with increasing concern for its toxicity to aquatic wildlife through inadvertent exposures. To assess the likely adverse effects of PFOS exposure on aquatic wildlife inhabiting polluted ecosystems, there is a need to identify biomarkers of its exposure and toxicity. We used an integrated systems toxicological framework to identify physiologically relevant biomarkers of PFOS toxicity in fish. An in silico stoichiometric metabolism model of zebrafish (Danio rerio) was used to integrate available (published by other authors) metabolomics and transcriptomics datasets from in vivo toxicological studies with 5 days post fertilized embryo-larval life stage of zebrafish. The experimentally derived omics datasets were used as constraints to parameterize an in silico mathematical model of zebrafish metabolism. In silico simulations using flux balance analysis (FBA) and its extensions showed prominent effects of PFOS exposure on the carnitine shuttle and fatty acid oxidation. Further analysis of metabolites comprising the impacted metabolic reactions indicated carnitine to be the most highly represented cofactor metabolite. Flux simulations also showed a near dose-responsive increase in the pools for fatty acids and acyl-CoAs under PFOS exposure. Taken together, our integrative in silico results showed dyslipidemia effects under PFOS exposure and uniquely identified carnitine as a candidate metabolite biomarker. The verification of this prediction was sought in a subsequent in vivo environmental monitoring study by the authors which showed carnitine to be a modal biomarker of PFOS exposure in wild-caught fish and marine mammals sampled from the northern Gulf of Mexico. Therefore, we highlight the efficacy of FBA to study the properties of large-scale metabolic networks and to identify biomarkers of pollutant exposure in aquatic wildlife.

Repeated Divergence in Opsin Gene Expression Mirrors Photic Habitat Changes in Rapidly Evolving Crater Lake Cichlid Fishes.

AbstractSelection pressures differ along environmental gradients, and traits tightly linked to fitness (e.g., the visual system) are expected to track such variation. Along gradients, adaptation to local conditions might be due to heritable and nonheritable environmentally induced variation. Disentangling these sources of phenotypic variation requires studying closely related populations in nature and in the laboratory. The Nicaraguan lakes represent an environmental gradient in photic conditions from clear crater lakes to very turbid great lakes. From two old, turbid great lakes, Midas cichlid fish (Amphilophus cf. citrinellus) independently colonized seven isolated crater lakes of varying light conditions, resulting in a small adaptive radiation. We estimated variation in visual sensitivities along this photic gradient by measuring cone opsin gene expression among lake populations. Visual sensitivities observed in all seven derived crater lake populations shifted predictably in direction and magnitude, repeatedly mirroring changes in photic conditions. Comparing wild-caught and laboratory-reared fish revealed that 48% of this phenotypic variation is genetically determined and evolved rapidly. Decreasing intrapopulation variation as environments become spectrally narrower suggests that different selective landscapes operate along the gradient. We conclude that the power to predict phenotypic evolution along gradients depends on both the magnitude of environmental change and the selective landscape shape.

Trophic niche drives the evolution of craniofacial shape in Trinidadian guppies.

Diverse clades of fishes adapted to feeding on the benthos repeatedly converge on steep craniofacial profiles and shorter, wider heads. But in an incipient radiation, to what extent is this morphological evolution measurable and can we distinguish the relative genetic vs. plastic effects? We use the Trinidadian guppy (Poecilia reticulata) to test the repeatability of adaptation and the alignment of genetic and environmental effects shaping poecilid craniofacial morphology. We compare wild-caught and common garden lab-reared fish to quantify the genetic and plastic components of craniofacial morphology across 4 populations from 2 river drainage systems (n = 56 total). We first use micro-computed tomography to capture 3D morphology, then place both landmarks and semilandmarks to perform size-corrected 3D morphometrics and quantify shape space. We find a measurable, significant, and repeatable divergence in craniofacial shape between high-predation invertivore and low-predation detritivore populations. As predicted from previous examples of piscine adaptive trophic divergence, we find increases in head slope and craniofacial compression among the benthic detritivore foragers. Furthermore, the effects of environmental plasticity among benthic detritivores produce exaggerated craniofacial morphological change along a parallel axis to genetic morphological adaptation from invertivore ancestors. Overall, many of the major patterns of benthic-limnetic craniofacial evolution appear convergent among disparate groups of teleost fishes.

Zinc isotope composition of enameloid, bone and muscle of gilt-head seabreams (Sparus aurata) raised in pisciculture and their relation to diet

The isotope ratios of zinc (66Zn/64Zn expressed as δ66Zn), a vital nutrient, increasingly demonstrate trophic discrimination among vertebrates, making δ66Zn a valuable dietary proxy for ecological, archaeological, and palaeontological studies. Given the novelty of the methodology, tissue-diet and tissue-tissue zinc isotope fractionation factors remain poorly understood and have so far only been studied in a few terrestrial mammals. Here, we investigate δ66Zn compositions of enameloid, bone, and white muscle of seven artificially-fed pisciculture gilt-head seabreams (Sparus aurata) from offshore Israel, in comparison to the Zn isotope composition of their diet. In addition, we also analysed δ66Zn values in the same tissues of wild-caught S. aurata, bluespotted seabream (Pagrus caeruleostictus) and grey triggerfish (Balistes capriscus) caught off the coast of Israel. We determine a tissue-diet δ66Zn offset for Sparus aurata of − 0.04 ± 0.09 ‰ (2SD) for bone, − 0.29 ± 0.06 ‰ (2SD) for enameloid, and − 0.45 ± 0.07 ‰ (2SD) for white muscle. Wild-caught fish have much higher among-individual δ66Zn variability with values distinct from the pisciculture S. aurata, documenting a much more isotopically heterogeneous diet consumed by the wild individuals. Still, tissue–tissue δ66Zn differences in wild-caught individuals are close to those observed in the pisciculture ones with progressively lower δ66Zn values in the order bone > enameloid > white muscle. Our results demonstrate predictable tissue-diet and tissue-tissue δ66Zn differences among fish hard and soft tissues and can be applied to identify the δ66Zn values of dietary input, thereby informing trophic (palaeo)ecological reconstructions.

Human health risks associated to trace elements and metals in commercial fish from the Brazilian Amazon

Fish constitutes the main protein source for the Amazonian population. However, the impact of different anthropogenic activities on trace element and metal accumulation in fish and their risks for human health at a regional scale remain largely unexplored. Here we assessed exposure levels of 10 trace elements and metals (Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Pb, and Hg) in 56 samples belonging to 11 different species of fish from the Brazilian Amazon. We studied the relationship between exposure levels, fish origin, and fish feeding habits, and assessed toxicological and carcinogenic risks for the Amazonian population. No significant correlation was found between sampling site and exposure levels to the studied elements, but a significant difference was found between the accumulation of some metals and the position of the fish species in the food chain. The concentrations of Cr and Hg in fish flesh were found to exceed the Brazilian limits for human consumption. This study shows that current fish consumption patterns can lead to estimated daily intakes of Hg, As and Cr that exceed the oral reference dose, thus posing a toxicological concern. Furthermore, carcinogenic risks may be expected due to the continued exposure to Cr and As. The results of this study show that the consumption of wild caught fish in the Amazon region should be controlled. Moreover, continued monitoring of trace element and metal contamination in fish and on the health of the Amazonian population is recommended, particularly for riverine and indigenous communities.

Estimating global numbers of fishes caught from the wild annually from 2000 to 2019.

Finfishes are caught from the wild for food, feed (often in the form of fishmeal and oil) and bait. According to the Food and Agriculture Organisation of the United Nations (FAO), between 74 and 83 million tonnes (averaging 77 million tonnes) were caught annually in 2000-2019. Although fishes are now widely recognised as sentient beings, capture is still quantified as biomass rather than number of individuals (in contrast to wild-caught marine mammals and crocodiles; and farmed mammals and birds). Here, we estimate global numbers of wild-caught finfishes using FAO capture production (landing) tonnages (2000-2019 data) and estimates of mean individual weight at capture, based on internet-sourced capture and market weights. We estimate that between 1,100 and 2,200 billion (1.1-2.2 × 1012), or 1.1-2.2 trillion, wild finfishes were caught annually, on average, during 2000-2019. Anchoveta (Engraulis ringens) comprised 28%, by estimate midpoint. Estimated numbers in 2019, totalling 980-1,900 billion, were lower due to reduced anchoveta landings, but still represented 87.5% of vertebrate numbers killed for food or feed, as obtained or estimated from FAO data. These figures exclude unrecorded capture such as illegal fishing, discards and ghost fishing. Estimated finfish numbers used for reduction to fishmeal and oil represented 56% of the total 2010 estimate (1,000-1,900 billion), by midpoint. It is recommended that the FAO reports fish capture numbers. The welfare of wild-caught fishes, which is generally very poor during and after capture, should be addressed as part of sustainable utilisation of aquatic resources.

Androgen receptors rapidly modulate non-breeding aggression in male and female weakly electric fish (Gymnotus omarorum)

The South American weakly electric fish, Gymnotus omarorum, displays territorial aggression year-round in both sexes. To examine the role of rapid androgen modulation in non-breeding aggression, we administered acetate cyproterone (CPA), a potent inhibitor of androgen receptors, to both male and females, just before staged agonistic interactions. Wild-caught fish were injected with CPA and, 30 min later, paired in intrasexual dyads. We then recorded the agonistic behavior which encompasses both locomotor displays and emission of social electric signals. We found that CPA had no discernible impact on the levels of aggression or the motivation to engage in aggressive behavior for either sex. However, CPA specifically decreased the expression of social electric signals in both males and female dyads. The effect was status-dependent as it only affected subordinate electrocommunication behavior, the emission of brief interruptions in their electric signaling (“offs”). This study is the first demonstration of a direct and rapid androgen effect mediated via androgen receptors on non-breeding aggression. Elucidating the mechanisms involved in non-breeding aggression in this teleost model allows us to better understand potentially conserved or convergent neuroendocrine mechanisms underlying aggression in vertebrates.

Potentiality of natural live food organisms in shrimp culture: A review

The aquaculture industry is growing quickly due to increased fish consumption and a decline in wild fish catch. About half of the world's seafood demand for human consumption is now met by farmed seafood. The aquafeed market is expanding along with the aquaculture sector. Some of the elements in shrimp feed are derived from terrestrial plants and low-value forage fishes (fish meal). It is impossible to produce more fish meals since doing so would harm the ocean's environment and sustainability. The reduction in shrimp feed cost can also be done by introducing low-cost, environment-friendly ingredients in shrimp feed formulation. Therefore, new and ecologically friendly shrimp (Litopenaeus vannamei) feed component sources must be created. Live food organisms are a preferable option for this since they provide a variety of essential amino acids and beneficial triglycerides like fat, vitamins, and colors in their cell metabolites. Microalgae biomasses also represent feasible ingredients for shrimp feed sources. Their distinctive variety of bioactive chemicals can enhance color and pellet quality, act as a bulk element in shrimp feed, and boost the viability of farmed species. Live food organisms have a great economic potential since they have the highest biomass productivity of all photosynthetic organisms. In addition to giving farmers and exporters a better choice for feeding their fish, the availability of on-grown live food would also open up the prospect of improving the performance and quality of the fish and shrimp through bioencapsulation. This review study examines the possibility of generating natural food biomass as a component in shrimp feed.

Detection of different Betanodavirus genotypes in wild fish from Spanish Atlantic coastal waters (Galicia, northwestern Spain).

The nervous necrosis virus (NNV; genus Betanodavirus) is an aquatic pathogen that is responsible for a neurological disease affecting marine fish. Despite its almost worldwide distribution, global warming could favor the spread of NNV to new areas, highlighting the importance of conducting epidemiological surveys on both wild and farmed marine fish species. In this study, we assessed NNV prevalence in wild fish caught along the Galician Atlantic coast. In total, 1277 fish were analyzed by reverse transcription real-time polymerase chain reaction. Twenty two (1.72%) of those fish tested positive for NNV, including two species in which the pathogen had not yet been reported. The reassortant RGNNV/SJNNV (red-spotted grouper NNV/striped jack NNV) was detected in 55% of NNV-positive individuals, while the remaining 45% harbored the SJNNV-type genome. Moreover, from European Pilchard Sardina pilchardus and Atlantic Mackerel Scomber scombrus, we isolated four reassortant strains that carried amino acid mutations at key sites related to NNV-host interaction.