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ABSTRACT The minute intestinal trematode Centrocestus formosanus is a major problem that can be found in the gills of various fish species. This parasite can destroy the gill structure of fish, leading to increased fish morbidity and mortality rates. In this study, loop‐mediated isothermal amplification (LAMP) based on the internal transcript spacer 1 region combined with a lateral‐flow dipstick (LAMP‐LFD) assay was used to detect C. formosanus in goldfish, Carassius auratus. The results showed that LAMP‐LFD was specific to C. formosanus and had no cross‐amplification with other co‐infecting parasite species, close related parasite species or their hosts (both intermediate host and definitive host). The limit of detection is as low as one metacercaria per gill. In testing 40 goldfish gill samples, the LAMP‐LFD method showed 100% accuracy when compared to traditional morphological identification. This method can be used as a rapid diagnostic tool for C. formosanus detection to obtain epidemiological information for monitoring, controlling, and preventing outbreaks of this parasite. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate the parasitic nematode infecting the bile ducts of striped catfish. A total of 1570 fish specimens, weighing between 400.5 and 899.1 g each, were examined. A parasitological analysis revealed that 607 fish samples were infected with nematodes, with typical clinical signs including swollen in both the common bile duct and gallbladder, several white cysts in the common bile ducts, and gallbladders exhibiting a dark green coloration. Examination of the common bile ducts in striped catfish revealed the presence of two distinct parasitic nematode morphotypes. Free-living nematodes were observed residing within the lumen, the central cavity, of the common bile duct. Additionally, larval nematodes were encapsulated within cysts lining the duct wall, suggesting a more chronic parasitic association. The infection rate of worms in the common bile duct was prevalent from November to April, with the most significant infection rate occurring in March (67.1%). The intensity of free-living nematode infection was the peak in March, with a mean of 6.7 ± 1.5 worm/gallbladder, and the peak level of larval nematode encapsulation was in November, with 9.4 ± 3.8 encysted larvae/common bile duct. The highest cumulative fish mortality rate was observed in February (2.1 ± 0.4%). Morphological analysis revealed the roundworms to be white and elongated with a slight narrowing at the mid-esophageal region. The mouth extended posteriorly towards the abdomen, and a well-developed, funnel-shaped esophagus was observed. Further analysis using 18S rRNA gene sequencing confirmed the identity of the parasite within the common bile duct of striped catfish as Cucullanus bourdini. [ABSTRACT FROM AUTHOR]

ABSTRACT During spring 2024, a heat wave induced sustained water temperatures of 34°C during a week in Veracruz, Mexico. Serendipitously, we monitored Gyrodactylus cichlidarum infecting farmed tilapia fry during this pulse warming event and recorded a drastic decline of parasite populations over the following days. We subsequently established that parasites incubated in vitro at ca. 27°C survived up to 24 h, while at ca. 30°C and 34°C, all worms died within 4–7 h. Abnormal haptor structures were observed in parasites that developed and were born at a water temperature of 34°C. Under farming conditions, no unusual fish mortality was recorded, suggesting that pulse heat treatment may be an effective method to control G. cichlidarum, a recognised tilapia pathogen. [ABSTRACT FROM AUTHOR]

In this study, we simulated water temperature changes under variable frequency temperature rise conditions caused by coastal nuclear power plant discharges and conducted thermal shock tests on four fish species: Trachinotus ovatus, Nibea albiflora, Larimichthys crocea, and Acanthopagrus schlegelii at acclimated water temperatures of 25.0°C and 27.5°C during the summer. The effects of these temperature variations on the thermal shock response of the four fish species were analyzed. The results indicated that at 25.0°C, the mortality rate of N. albiflora exhibited an overall upward trend with increasing temperature and duration frequency, with an average mortality rate ranging from 10±3.3% to 38.9±3.3%. For L. crocea, mortality was observed only in the 8.5°C-100% duration probability group, while other groups had a 0% mortality rate. At 27.5°C, A. schlegelii showed an average mortality rate of 10±3.3% at an 8.5°C-100% duration probability, with all other groups showing 100% survival. The average mortality rate of T. ovatus at 8.5°C-100% was 6.7±3.3%, with no mortality in the other treatment groups. The expression level of the hsp70 gene in the liver of N. albiflora increased with higher temperature rise amplitudes and longer frequency conversion durations. Similarly, the hsp70 gene expression in L. crocea and A. schlegelii increased with rising temperatures, though there were no significant differences among groups with varying frequency conversion times. In contrast, the hsp70 gene expression in T. ovatus remained relatively stable across temperature rise treatments, showing no significant differences with varying frequency conversion durations. The heat stress tolerance ranking among the four fish species was determined to be L. crocea > N. albiflora > T. ovatus > A. schlegelii. [ABSTRACT FROM AUTHOR]

The stock assessment model for the Antarctic krill fishery is a population model operating on daily timesteps, which permits modeling within‐year patterns of some population dynamics. We explored the effects of including within‐year patterns in natural and fishing mortality on catch limits of krill, by incorporating temporal presence of key predator species and contemporary temporal trends of the fishing fleet. We found that inclusion of within‐year variation in natural and fishing mortalities increased catch limits. Fishing mortality had a greater effect than natural mortality despite differences in top‐down predation on krill, and potentially increased catch limits by 24% compared to the baseline model. Additionally, the stock assessment model allowed a higher catch limit when fishing was during peak summer months than autumn. Number of days with active fishing was negatively related to precautionary catch limits. Future stock assessments should incorporate contemporary spatiotemporal fishing trends and consider implementing additional ecosystem components into the model. [ABSTRACT FROM AUTHOR]

Sinipercachuatsi rhabdovirus (SCRV) has caused severe disease and mortality in commercial fish in China. To investigate the molecular relationships between pathogen and host, transcriptome analysis of SCRV-infected and non-infected E11 cells was obtained using the Illumina HiSeq X Ten sequencing system. A total of 29,894 unigenes were assembled and a total of 4137 differentially expressed genes (DEGs), consisting of 2189 up-regulated and 1948 down-regulated unigenes, were detected between SCRV-infected and non-infected E11 cells. To understand the immune response of the host against the virus, pathway function analysis indicates that SCRV infection affected 31 typical immune-related pathways, including MAPK signaling pathway, PI3K-Akt signaling pathway, endocytosis, and apoptosis, suggesting that E11 cells resist SCRV invasion through these innate immune pathways. Overall, qRT-PCR results showed similar expression to Illumina HiSeq, with reliable sequencing results. These results provided some vital clues which will be helpful for future study on SCRV-host interactions. [ABSTRACT FROM AUTHOR]

Fishery stock assessment is the basis of fishery management. This study explored the applicability of the Length-Based Spawning Potential Ratio method (LBSPR) to assess the exploitation status of data-limited fisheries. Using data from bottom trawl surveys in Zhanjiang Bay, the study estimated the relative fishing mortality (F/M) of Johnius belangerii stock. The results showed that the average lengths at 50% and 95% selectivity (LS50 and LS95) were 105 mm and 145 mm, respectively, both of which are smaller than the lengths at 50% and 95% sexual maturity length (L50 = 125 mm and L95 = 167 mm) determined via the logistic curve. The estimated spawning potential ratio (SPR) was 0.15 significantly below the reference threshold of 0.2. The study recommended the establishment of a minimum size range (137 to 150 mm) length for harvesting Johnius belangerii to enhance their reproductive potential. It also emphasized the importance of scientific monitoring of fishery resources and the ecological environment in Zhanjiang Bay to ensure sustainable management. [ABSTRACT FROM AUTHOR]

ABSTRACT The Atlantic surfclam, Spisula solidissima supports a lucrative commercial fishery in the Mid‐Atlantic Bight (MAB) worth roughly $30 million in revenue per year. Rapid climate change is expected to modify the geographic range of the Atlantic surfclam, with consequences for the surfclam fishery. This study evaluated fishery‐based indicators projected from 2020 through 2095 based on anticipated changes in the geographic range and biomass of the Atlantic surfclam, using a Spatially Explicit, agent‐based Fisheries and Economics Simulator (SEFES). Simulations generally showed a positive trend in Atlantic surfclam biomass throughout the next three‐quarters of the 21st century as the clam's range continues to shift offshore and northward along the continental shelf. A general decrease in fishing mortality rate is projected given the present fleet capacity, with a simultaneous increase in catch and landings per unit effort (LPUE), signaling future potential growth in the surfclam fishery. Regionally, forecasts show biomass expanding into deeper waters particularly off New Jersey, Long Island, and southern New England starting in the early 2050s, whereas populations on Georges Bank and off Delmarva gradually decline. Trends in time spent fishing, catch, and LPUE parallel those of biomass in each region. These results can inform managers and business interests that rely on this fishery, as well as other users of the continental shelf, to provide a basis for the development of anticipatory management for the socio‐ecological and economic impacts that may result from future changes in the Atlantic surfclam range and carrying capacity consequent of climate change. [ABSTRACT FROM AUTHOR]

Featured Application: Machine learning model applications provide enough evidence to predict fish stock using aquaculture data, allowing for significant practical implications. By applying advanced statistical models, including Random Forest, Decision Tree, and Linear Regression, aquaculture stakeholders can improve their decision-making processes by predicting fish populations, mortality rates, and other critical metrics. Among the predictive models, the Random Forest model outperformed other models, reaching the highest accuracy. This allows more efficient and productive management strategies, supports sustainable development, and helps policymakers in enhancing decision-making to protect marine ecosystems. The dynamic for integrating such tools, such as predictive statistical models into real-time monitoring systems, provides a proactive strategy for aquaculture growth, risk mitigation, and long-term sustainability. The current study evaluates the performance of three machine learning models—Decision Trees, Random Forest, and Linear Regression—applied to aquaculture data to mitigate risks in aquaculture management. The performances of these models are analyzed and properly demonstrated using metrics including the Mean Squared Error (MSE), R-squared (R2), Root Mean Squared Error (RMSE), and Concordance Index (C-index). The Random Forest model achieved the highest prediction accuracy among all machine learning models, followed by Linear Regression and the Decision Trees. The scatter plot for Linear Regression demonstrates good predictive accuracy for mid-range values. However, it shows significant deviations at the extremes, indicating that the model struggles to capture the full range of variability in the data. The bar chart of coefficients pinpoints the variables with the greatest impact on the predictions, providing suggestions for potential areas that can be improved and providing model interpretability. Future work could incorporate more predictive statistics models focusing on improving the models for extreme values by assessing non-linear models, feature engineering methods, and expanding research into less influential variables. The results greatly impact several sections, including aquaculture management, policy-making, and operational strategies, providing valuable insights for stakeholders and decision-makers. Apache Spark was used for data processing and machine learning model implementation; Apache Cassandra was also used for data storage, ensuring efficient large dataset management and SQL tools for structured data handling; Oracle VM VirtualBox for cross-platform virtualization; and Spark Connector was also used. [ABSTRACT FROM AUTHOR]

Large high-head centrifugal pumps have the characteristics of large flow rate, high head, and high specific speed, making them important engineering equipment in large-scale water transfer projects. However, these pumps inevitably cause the death of a large number of fish during operation, which has adverse effects on the ecological environment. Therefore, studying the damage of large high-head centrifugal pump stations on fish is of great significance. This article establishes a new mathematical model for blade strike and predicts the strike probability and mortality rate of fish passing through the inlet of the centrifugal pump impeller. The prediction results show that under various flow conditions, the strike mortality rate for 50 mm fish passing through the model pump exceeds 82.5%, indicating that the model pump will cause significant damage to the pumped fish. This article further investigates the damage to fish caused by unstable flow inside the impeller and diffuser in low-pressure, high-shear, and high-pressure gradient regions. The research results show that fish suffer less low-pressure damage and more high-pressure gradient damage while passing through the model pump. [ABSTRACT FROM AUTHOR]

Background/Objectives: Maintaining an optimum transport density is essential for protecting water quality, lowering stress levels, and increasing fish survival rates. Transporting marine fish fry involves major dangers. The purpose of this study was to evaluate the impact of transport stress at varying densities on the immune-related gene expression, antioxidant capacity, and survival rate of yellowfin seabream (Acanthopagrus latus) fry. Methods: A 12 h simulated transport experiment was conducted with A. latus fry divided into six density groups. For 1–2 cm fry, densities of 900, 1200, and 1500 fry per pouch were used to assess antioxidant enzyme activity; and for 4–5 cm fry, densities of 100, 125, and 150 fry per pouch were used for gene expression analysis. The key parameters measured included survival rates, antioxidant enzyme activities in liver and intestinal tissues, and expression levels of HSP90α and caspase-3 genes. Results: The findings showed that recovery time and density both affected the observed responses and that transport density had a substantial effect on antioxidant enzyme activity in all tissues. The intestinal and liver tissues showed a considerable decrease in antioxidant enzyme activity, suggesting that these tissues may be able to respond to oxidative stress. Moreover, under high-density transport conditions, there were notable increases in the expression of caspase-3 and HSP90α, suggesting the activation of immune response systems. This research offers valuable new understandings into the relationship between transport density and immunological and antioxidant modulation in A. latus fry. Conclusions: The results provide a scientific foundation for enhancing aquaculture transport conditions, which will ultimately lead to decreased fish mortality and improved general health during transit, resulting in more sustainable and effective aquaculture methods. [ABSTRACT FROM AUTHOR]

Simple Summary: Streptococcus agalactiae, a significant pathogen affecting humans and aquatic species, is causing high morbidity and mortality in fish, particularly Nile tilapia (Oreochromis niloticus). This study focuses on S. agalactiae infection in cultured O. niloticus, examining transmission, sources, risk factors, clinical signs, pathogenesis, virulence factors, and methods for diagnosis, treatment, control, and prevention. Streptococcus agalactiae (Group B Lancefield) has emerged as a significant pathogen affecting both humans and animals, including aquatic species. Infections caused by S. agalactiae are becoming a growing concern in aquaculture and have been reported globally in various freshwater and marine fish species, particularly those inhabiting warm water environments. This has led to numerous outbreaks with high morbidity and mortality in fish. Nile tilapia (Oreochromis niloticus), a member of the Cichlid family, is one of the severely affected fish species by S. agalactiae. The current study aims to focus on S. agalactiae infection in cultured O. niloticus with reference to its transmission and sources of infection; risk factors influencing GBS infection, disease clinical signs, lesions, and pathogenesis; S. agalactiae virulence factors; and how to diagnose, treat, control, and prevent infection including vaccination and herbal extract medication. [ABSTRACT FROM AUTHOR]

A 2-week rapid fishery assessment using various sampling gears was conducted to collect life-history data on rednose labeo Labeo rosae and Mozambique tilapia Oreochromis mossambicus in Loskop Dam on the Olifants River, Mpumalanga Province, South Africa. These native species were the two most-abundant fish species caught in the impoundment during the study. Both species displayed a bimodal population size distribution comprised of recent recruits and large-sized individuals. Isometric growth (b value ∼3), an asymptotic length (L∞) of 447 mm, and length at 50% sexual maturity (Lm50) of 198 mm were estimated for L. rosae. Isometric growth, L∞ of 451 mm, and Lm50 of 124 mm were estimated for O. mossambicus. This rapid assessment at Loskop Dam produced sets of life-history parameters comparable to those previously reported for these two species in Flag Boshielo Dam, ∼80 km downstream. [ABSTRACT FROM AUTHOR]

Home range size is a fundamental trait that can affect the probability of fish being harvested and, at the same time, may be affected by fishing. The relationship between home range size and fishing will impact the effectiveness of fully protected areas (FPAs), as it will influence the number of fish moving into fished areas, affecting both spillover and edge effects. One hypothesis is that individuals within FPAs will present reduced home range size relative to individuals in fished areas. This pattern can be driven by demographic selection (e.g. fishing of individuals with large home ranges leaving the FPAs), improved habitat requiring less foraging movements, or behavioural changes associated with reduced fishing threats. To test the relationship between home range size and protection, we compiled 1143 individual‐level home range sizes based on acoustic tracking, covering 17 species from 11 FPAs in 7 countries, with information on distance from FPA borders. A dichotomic analysis (in/out of FPAs) did not support a significant change in the home range size between FPAs and fished areas. However, continuous analysis across the FPA borders demonstrated reduced home range size within the FPAs. We did not find an effect of FPA age or size on this pattern. While we cannot pinpoint the underlying mechanism for the pattern revealed, we suggest behavioural changes as the main driver for reduced home range within FPAs. This mechanism will lead to more resident populations within FPAs, reducing fishing mortality within FPAs yet limiting spillover benefits to adjacent fisheries. [ABSTRACT FROM AUTHOR]

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Fish diseases are among the major limiting factors to increase global aquaculture production. They lead to increased fish mortality, low breeding and growth rates, and low meat quality. The success of aquaculture is heavily dependent on the timely identification of disease. Therefore, we propose a fuzzy U-Net model to automatically identify fish disease from underwater images. U-Net is enhanced with multi-head channel and spatial attention and used to segment infected fish regions from fish disease images. Color pixel intensity features are then extracted from the localized regions, a form of guided feature extraction. Fuzzy C-means clustering is then used to find the cluster centroids and data distribution within the clusters, for the design of fuzzy membership functions. Moreover, the number of clusters are determined by silhouette score. Adaptive neuro-fuzzy inference system (ANFIS) is then trained, tested, and cross-validated for fish disease identification. The model parameters are optimized using particle swarm optimization (PSO) algorithm and compared with gradient-based methods. For image segmentation, the enhanced U-Net achieved a mean intersection over union (IoU) of 86.29%, mean pixel accuracy of 90.94%, mean precision of 93.58%, and mean recall value of 89.94% on 42 test images. Subsequently, ANFIS with PSO achieved overall superior performance on fish disease identification over gradient-based methods, with accuracy of 99.31%, precision of 99.00%, recall of 99.00%, and F1-score of 99.00%. The high-performance results of the optimized ANFIS confirm the robustness and efficacy of the proposed method to automatically identify fish diseases in aquaculture. [ABSTRACT FROM AUTHOR]

Water temperature is a critical factor for aquatic ecosystems, influencing both chemical and biological processes, such as fish growth and mortality; consequently, river and lake ecosystems are sensitive to climate change (CC). Currently proposed CC scenarios indicate that air temperature for the Mediterranean Jucar River will increase higher in summer, 4.7 °C (SSP5-8.5), resulting in a river water temperature increase in the hotter month; July, 2.8 °C (SSP5-8.5). This will have an impact on ecosystems, significantly reducing, fragmenting, or even eliminating natural cold-water species habitats, such as common trout. This study consists of developing a simulated model that relates the temperature of the river with the shadow generated by the riverside vegetation. The model input data are air temperature, solar radiation, and river depth. The model proposed only has one parameter, the shadow river percentage. The model was calibrated in a representative stretch of the Mediterranean river, obtaining a 0.93 Nash–Sutcliffe efficiency coefficient (NSE) that indicates a very good model fit, a 0.90 Kling–Gupta efficiency index (KGE), and a relative bias of 0.04. The model was also validated on two other stretches of the same river. The results show that each 10% increase in the number of shadows can reduce the river water temperature by 1.2 °C and, in the stretch applied, increasing shadows from the current status of 62% to 76–87% can compensate for the air temperature increase by CC. Generating shaded areas in river restorations will be one of the main measures to compensate for the rise in water temperature due to climate change. [ABSTRACT FROM AUTHOR]

Fisheries management needs to ensure that resources are exploited sustainably and the risk of depletion is at an acceptable level. In developing countries, multi-gear, multispecies fisheries often lack data, making conventional stock assessment approaches unsuitable. Data-limited methods have been developed to compare quantitative measures of fishery and stock status with management and biological reference points. In Morocco, despite its large productive ecosystems, most of the fishing stocks remain unassessed.Weselected a stock of chub mackerel, considering the availability of survey data, and the fact that it occupies an important place in small pelagic resources. Although this is an important stock, there is a lack of new information on migration and possible exchange between the two stocks of chub mackerel (central and southern). This study presents the first attempt at a combined assessment to provide Maximum Sustainable Yield (MSY) estimates and related indicators of the Moroccan chub mackerel (center and south) by using two of the most used data-limited approaches, the Stochastic Surplus Production model in Continuous Time (SPiCT) and the Length Based Spawning Potential Ratio estimation (LBSPR).Thesetwoapproacheswereappliedtoanalyze thechubmackerel stock state and estimate how far away it was from the estimated harvest relative to MSY using all available time series data. The findings provide valuable informationonMSY advice for this stock while remarking the advantages and limitations of two data-limited approaches for the assessment of chub mackerel. The SPiCT results show that the current harvest level closely aligns with the estimated MSY, and that the estimated biomass (B) is below BMSY, and the estimated fishing mortality (F) exceeds FMSY. For LBSPR, most SPR values are lower than the reference point of 40%, which serves as a proxy for BMSY, indicating also a biomass below BMSY. Both models suggest full to overexploited stock status mainly for the period (2016-2020), and this is a different perception to the one provided only by analyzing survey indices fluctuations that indicate critical status over a longer period. Then, this exercise is also pointing out the importance of having different data sources for a better stock status estimation. [ABSTRACT FROM AUTHOR]

Risk and uncertainty are intrinsic characteristics of natural resources that must be taken into account in their management. Harvest control rules (HCR) used to be the central management tool to control stock fisheries in an uncertain context. A typical HCR determines fishing mortality as a linear relationship of the biomass binding only when the biomass is above a critical risk value. Choosing the linear relationship and the risk value is a complex task when there is uncertainty because it requires a high level of data and an in-deep knowledge of the stock. This paper fully characterizes robust HCRs that explicitly include scientific uncertainty using the robust control theory approach. Our theoretical findings show that under uncertainty: i) Constant HCRs are not robust; ii) Robust HCRs show a steeper linear relationship between fishing mortality and biomass and a higher value of biomass to be consider at risk than non-robust HCRs. From the implementation viewpoint, we assume a three-sigma rule and show that robustness is achieved by selecting a fishingmortality such that its deviation fromthe fishingmortality target is twice the deviation of the biomass from the biomass target, and the critical value of the biomass (the point below which fishing should cease, or become as close to zero as possible) is half of the biomass associated with the maximum sustainable yield when this is the target. [ABSTRACT FROM AUTHOR]

One of the most farmed fishes is the African catfish, Clarias gariepinus. Its production has increased by 20% annually on average during the last 20 years, but the occurrence of fish diseases, especially bacterial such as Aeromonas hydrophila infections, is hindering its activities. Also, the incorporation of plant‐derived substances in aquafeeds is limited since they frequently contain different antinutritional factors, like nonstarch polysaccharides (NSPs). However, supplementing fish diets with β‐mannanase could increase growth, antioxidants, and immunity. Despite the advantage of β‐mannanase, its effects on growth, digestive enzymes, antioxidants, and immunity in African catfish need to be elucidated. This study examined the effects of dietary β‐mannanase on the growth performance, liver enzymes, antioxidant profiles, immunity, and protection of African catfish, C. gariepinus, against A. hydrophila infection. Five isonitrogenous diets were prepared to have 400 g/kg crude protein and supplemented with β‐mannanase at 0, 1500, 3000, 4500, or 6000 thermostable endo, 1,4‐β‐mannanase units (TMUs)/kg diet and fed to 300 juveniles of the African catfish, C. gariepinus (mean weight 12.1 ± 0.1 g) for 12 weeks. Then, 10 fish from each tank received an intraperitoneal injection of 0.1 mL of A. hydrophila (5.0 × 105 CFU/mL) and observed for 14 days. Results showed dietary β‐mannanase levels considerably improved growth performance but did not affect fish survival. Also, amylase, protease, and lipase levels were significantly promoted in the fish fed with β‐mannanase‐fortified diets than the control group (p < 0.05). Enhanced gut villi and intestinal absorption areas, haematlogical profiles, and liver enzymes but reduced gut viscosity were observed in fish‐fed β‐mannanase‐fortified diets (p < 0.05). In a dose‐dependent order, including β‐mannanase in the meals of African catfish raised the levels of glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), glutathione‐S‐transferase (GST), and glutamate cysteine ligase (GCL) activities and decreased the malondialdehyde (MDA) values in African catfish (p < 0.05). Also, fish immunity was greatly (p < 0.05) enhanced due to supplementation of the diet with β‐mannanase. In addition, fish‐fed diets comprising 6000 TMU β‐mannanase/kg diet showed the lowest rates of fish mortality (7.5%) (p < 0.05). Therefore, feeding African catfish, Clarias gariepinus, β‐mannanase enhanced growth performance, increased activity of digestive enzymes, gut morphology, enhanced generation of short‐chain fatty acids, digesta potential of hydrogen (pH), and improved antioxidant profiles and immunity at the optimum dose of 5800 TMU/kg diet. Additionally, β‐mannanase protected African catfish against A. hydrophila infection. [ABSTRACT FROM AUTHOR]

The growth of animal aquaculture requires ever more feed. Yet, fish and crustacean farming is argued to be sustainable because wild fish use is low and has improved over time. Here, accounting for trimmings and by-products from wild fish in aquaculture feed, and using four different sources of industry-reported feed composition data, we find ratios of fish inputs to farmed outputs of 0.36 to 1.15--27 to 307% higher than a previous estimate of 0.28. Furthermore, a metric that incorporates wild fish mortality during capture and excludes unfed systems raises the wild fish mortality-to-farmed fish output ratio to 0.57 to 1.78. We also evaluate terrestrial ingredients in aquaculture feeds. Widely cited estimates of declines in wild fish use from 1997 to 2017 entailed a trade-off of more than fivefold increase in feed crops over the same period. Our assessment challenges the sustainability of fed aquaculture and its role in food security. [ABSTRACT FROM AUTHOR]

Simple Summary: The cultivation of the Pacific fat sleeper (Dormitator latifrons) is of commercial interest in the Eastern Central Pacific. Its domestication potential is affected by the presence of pathogens. This study aimed to identify two trichodinid ectoparasites that are associated with D. latifrons larval mortality. We evaluated a total of 4320 fish larvae, 1080 fish larvae per treatment, revealing the presence of T. acuta and T. compacta in one treatment. Larval mortality in the infected treatment reached up to 58% by the fourth day post-hatching, at 28 °C, due to Trichodina infestation, resulting in significantly lower survival in the infected tanks compared to the uninfected tanks. This is the first geographical record of these protozoan parasites in a species that is native to the East Central Pacific Basin and intended for culture. Trichodinidae, a prevalent group of protozoan ectoparasites in aquaculture, cause rapid mortality in fish hatcheries. Despite their significance, knowledge about these parasites in farmed fish in South America, especially in native species that are currently being domesticated for aquaculture, remains limited. This study morphologically characterized the Trichodinid species that are infecting Pacific fat sleeper (Dormitator latifrons) larvae and evaluated their impact on larval rearing. Four pairs of broodstock were induced with GnRHA implants and placed in tanks containing 200 L of freshwater, with a water temperature of 28 ± 1.0 °C and a dissolved oxygen level of 4.00 ± 1.23 mg L−1, with partial water exchanges being performed daily. The larvae hatched 7 to 8 h after fertilization and were transferred to tanks containing water with the same quality parameters. Twelve hours post-hatching, the presence of Trichodina was observed. Every 24 h, 60 larvae per tank (n = 180 per treatment) were sedated, and larval wet mounts were prepared, air-dried at room temperature, and impregnated with silver nitrate. Infection parameters and daily mortality were calculated. Trichodina was observed to parasitize the pelvic fins, caudal fins, and heads of fish larvae, which showed lethargy and erratic swimming movements. The Trichodina species showed a daily increase in the infection parameters, and a 58% rate of larval mortality was observed at the fourth day post-hatching (dph) in the infected tanks. In captivity, D. latifrons larvae typically survive up to 7 days post-hatching (dph) before reaching their point of no return due to the lack of adequate diet and feeding regimes. However, our study indicates that Trichodina infestation accelerates mortality, causing infected larvae to die more quickly than uninfected ones. [ABSTRACT FROM AUTHOR]

Background: Streptococcus agalactiae (Group B streptococcus, GBS) induces a serious infection that can harm not only aquatic life but also humans and other animals. In a fish farm in southern Egypt, Nile tilapia (Oreochromis niloticus) has developed an epidemic with clinical symptoms resembling piscine streptococcosis. Results: Initial microscopic inspection of the affected fish brain and kidney indicated the presence of Gram-positive cocci. S. agalactiae was effectively isolated and identified using nucleotide homology of the 16S rRNA and species-specific PCR. The partial 16S rRNA sequence was deposited in the GenBank database at the NCBI and given the accession number MW599202. Genotyping using RAPD analysis indicated that the isolates in the present study belonged to the same genotypes and had the same origin. The challenge test, via immersion (9.2 × 107, 9.2 × 106, and 9.2 × 105 CFU/ml for 1 h) or intraperitoneal injection (4.6 × 107, 4.6 × 106, and 4.6 × 105 CFU/fish), elicited clinical symptoms resembling those of naturally infected fish with a mortality rate as high as 80%. The ability to create a biofilm as one of the pathogen virulence factors was verified. Zinc oxide nanoparticles and the ethanolic leaf extracts of nine medicinal plants demonstrated considerable antibacterial activities against the tested S. agalactiae strain with low minimum bactericidal concentrations (MBC) and minimum inhibitory concentrations (MIC). The ethanolic leaf extracts from Lantana camara and Aberia caffra showed potent antibacterial activity with MBC values of 0.24 and 0.485 mg/ml, and MIC values of 0.12 & 0.24 mg/ml, respectively. Conclusion: This study isolated S. agalactiae from O. niloticus mortalities in a fish farm in Assiut, Egypt. The pathogen persists in fish environments and can escape through biofilm formation, suggesting it cannot be easily eliminated. However, promising findings were obtained with in vitro control employing zinc oxide nanoparticles and medicinal plant extracts. Nevertheless further in vivo research is needed. [ABSTRACT FROM AUTHOR]

ABSTRACT Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD), is one of the leading pathogens in rainbow trout (Oncorhynchus mykiss) aquaculture. To date, there is little knowledge of the transmission kinetics of F. psychrophilum over the course of infection. In particular, how transmission is affected by host genotype and pathogen exposure dosage are not well studied. In order to fill in these knowledge gaps, we exposed two divergently selected lines of rainbow trout (ARS‐Fp‐R and ARS‐Fp‐S) to a range of dosages of F. psychrophilum (strain CSF117‐10). We then measured mortality and bacterial shedding to estimate transmission risk at multiple time points since initial infection. As dosage increased, the number of fish shedding and the amount of bacteria shed increased ranging from 0% to 100% and 103 to 108 cells fish−1 h−1, respectively. In addition, we found that disease resistance (survival) was not correlated with transmission risk blocking, in that 67% of fish which shed bacteria experienced no clinical disease. In general, fish mortality began on Day 3, peaked between Days 5–7 and was higher in the ARS‐Fp‐R line. Results from this study could be used to develop epidemiological models and improve disease management, particularly in the context of aquaculture and selective breeding. [ABSTRACT FROM AUTHOR]

During the flood season, high dam discharge rates result in total dissolved gas (TDG) supersaturation. This condition causes gas bubble trauma and can lead to fish mortality, which poses a significant threat to downstream river ecosystems. Assessing the ecological risks of TDG supersaturation is a challenge in waterpower-intensive river basins worldwide. Few studies have explored the impact of TDG supersaturation on fish behaviours, such as aggression and memory, which are crucial for feeding, reproduction, and predator avoidance. In this study, behavioural tests were conducted in a T-maze to investigate the effects of acute TDG supersaturation on swimming behaviour, aggression, and memory in medaka (Oryzias latipes). The results demonstrated that medaka exposed to TDG levels of 115% and 130% for 2 h had significantly reduced swimming performance.At TDG levels of 100%, 115% and 130%, medaka activity rates in the mirror arm of the maze in the mirror test were 44.34 ± 12.88%, 40.27 ± 15.44% and 35.35 ± 16.07%, respectively. Similarly, the activity rates of medaka in the active stimulus arm of the maze in the memory test were 50.35 ± 14.75%, 40.76 ± 12.51% and 35.35 ± 18.47%, respectively. The behaviour of medaka changed with increasing TDG supersaturation. These findings contribute to the development of an ecological risk assessment model for TDG supersaturation based on memory and aggression in fish and provide data for developing management strategies to mitigate the adverse effects of TDG supersaturation. [ABSTRACT FROM AUTHOR]

The status of Eastern Baltic cod (EBC) Gadus morhua has remained poor despite low fishing mortality for over a decade, including a fishing ban since 2019. Although the decline in productivity can be explained by lower individual growth and survival rates, other aspects of life‐history changes such as maturation patterns for EBC has so far not been sufficiently explored. According to current stock assessments, the median size at maturity (L50) has halved from 40 to around 20 cm in total length since the 1990s, while the overall size distribution has become increasingly truncated. It has previously been suggested that changes in L50 can be attributed to both fishing‐induced evolution and phenotypic plasticity induced by growth rates. However, since L50 is currently occurring around 20 cm, the maturation process must have been initiated at much smaller sizes, that is, long before the fish could be caught in the dominant trawl fishery at around 35 cm. In this study, we aimed to further investigate what drivers may have led to reduced productivity in EBC by determining variations in size at sexual maturity in longer time series than has been done before (1930s to 1980s) and include prey productivity and quality. We found that L50 declined already in the 1930s and thereafter remained stable at around 40 cm up to the 1990s. On a centurial perspective, L50 has been positively correlated to growth potential (L95), length diversity, total stock biomass, total catch and yield per recruit, while Fulton's condition factor was not related to L50. Our results suggest that the links between life‐history parameters and external drivers are complex, but the present unprecedented early onset of maturity and hence decline in L50 since the 1990s signals a decline in growth potential, which also has hampered the productivity of EBC. [ABSTRACT FROM AUTHOR]

Water diversions that support agricultural and municipal use result in fish mortality through entrainment and impingement. Additionally, this infrastructure may attract both predators and prey fishes, thereby increasing predation rates and prey mortality near these anthropogenic contact points. The Sacramento–San Joaquin Delta (the Delta) in California's Central Valley is a tidal freshwater ecosystem that exports large volumes of water for municipal and agricultural use while at the same time providing valuable migratory and rearing habitat for imperilled fishes. Emigrating juvenile salmonids experience high mortality in the Delta, with predation by non‐native fishes contributing substantially.Therefore, this study had three main objectives. First, we determined if small water diversions aggregated piscivorous fishes like other similar structures in freshwater ecosystems. Second, we determined how small diversions may influence juvenile salmon predation risk in conjunction with other known predation risk factors (e.g. predator abundance, temperature and depth). Third, we assessed the predator assemblage, abundance and distribution to determine the likely predator composition in objectives one and two.Throughout the spring of 2021, we used ARIS (adaptive resolution imaging sonar; Sound Metrics) sonars to compare piscivore abundance at 30 water diversions in the north Delta to shorelines adjacent to diversions that did not contain these structures. We used predation event recorders (PERs) to assess the predation risk juvenile salmonids were exposed to, with linear distance (m) from diversions, and other predation risk factors in the north Delta. Finally, we used a boat electrofishing survey to determine the piscivore assemblage and compare spatial trends in black bass (Micropterus spp.) CPUE and relative abundance throughout these waterways.Piscivore abundance was greater near small water diversions than at adjacent shorelines and the predation risk of juvenile salmonids increased with diversion proximity. Additionally, predation risk increased with increasing piscivore abundance and decreasing water depth. The north Delta predator assemblage was dominated by black basses (Micropterus spp.), which likely drove the negative relationship of predation risk with water depth, given habitat requirements of these species. Furthermore, increasing smallmouth (Micropterus dolomieu) and spotted bass (Micropterus punctulatus) abundance in our northern study sites may have weakened temperature effects on predation, given metabolic requirements of these species.Our work demonstrated that small water diversions are likely to increase mortality of endangered salmonids, and that the north Delta predator assemblage was different than recorded by previous work in this system, changing predation risk factors. Although more work is needed to determine the population level impacts of diversions, the ubiquitous distribution of these structures warrants management solutions to reduce mortality from this source.These results indicate that in addition to entrainment and impingement, water diversions may increase mortality of small‐bodied fishes by attracting predators and elevating predation risk. Given the continual human demand for freshwater, predator–prey interactions should be considered along with entrainment and impingement when assessing intake infrastructure mitigation, especially when diversions co‐occur along migratory routes and essential habitat of imperilled fishes. [ABSTRACT FROM AUTHOR]

Curcumin, a polyphenol, targets multiple signaling molecules and shows activity at the cellular level, supporting its various health benefits. Thereafter, the present study examines the effects of different doses of dietary curcumin on growth indices, feed efficiency, serum metabolites, redox (oxidation) status, immunity, histological assessment, and antioxidant-related genes in red tilapia (Oreochromis sp, Oreochromis aureus x O. mossambicus). A total of 1200 red tilapia with an average weight of 19.1±0.03 g were distributed in 12 cement ponds (3×3.5×1m). Each treatment was assigned three pounds (n=100 replicates). For 60 days, fish were fed baseline diets containing 0, 0.4, 0.6, and 0.8 g of curcumin/kg of diet. The treated fish showed increased body weight and SGR (specific growth rate) compared to the T0 group (P<0.05). Curcumin in the diet significantly improved weight gain, percentages, and FCR (feed conversion ratio), with a dose-dependent effect (P < 0.05). Curcumin supplementation showed no influence on feed intake, fish mortality, or survival rate (P >0.05). The curcumin-treated fish groups improved tissue structure in hepatocytes, pancreatic lumens, hepatic blood sinusoids, and intestine tissue layers, particularly the mucosal layer. The T0.8 group had reduced liver enzymes (AST and ALT) and greater total protein and albumin levels (P<0.05). The T0.6 and T0.8 groups showed significantly lower MDA levels than the other groups (P < 0.05). Curcumin groups demonstrated significantly higher antioxidant indices (CAT, GPx, and SOD) compared to the basal diet (P<0.05). Curcumin administration resulted in significant improvements in IgM and lysosome levels (P<0.05). All supplemented groups had considerably (P<0.05) higher levels of SOD, CAT, and GPx mRNA than the control group. Consequently, administering 0.6–0.8 g/kg of curcumin to red tilapia (Oreochromis sp.) diets may improve the fish's growth, health, tissue composition, and antioxidant response. [ABSTRACT FROM AUTHOR]

The purpose of the current study was to assess the effect of dietary supplements of either aqueous (AE) or ethanolic (EE) (Juniperus communis) leaf extracts on growth performance, intestinal health, hemato-biochemical indices, antioxidant, inflammation cytokine responses, and resistances against infection in Nile tilapia, Oreochromis niloticus. Fish groups were controlled with no extract (J1) and fed diets (J2, J3, J4, and J5) containing 1.0 and 2.0 g/kg aqueous and ethanolic extract for 60 days. Fish were given an intraperitoneal injection (IP) of Aeromonas hydrophila for 10 days after the feeding trial; then, the fish mortality was recorded. Growth, feed efficiency, and activity of endogenous enzymes (lipase, trypsin, chymotrypsin, and amylase) were significantly improved in all dietary J. communis groups, especially in J5, compared to other groups. Also, J5 showed the highest absorption area, muscularis, goblet cells, villi width, and fewer gut bacterial counts than the other groups. In addition, the J4 and J5 groups of tilapia fish exhibited a significant increase in the levels of total protein, serum albumin, globulin, hemoglobin, white blood cells, and hematocrit (P < 0.05), as well as a significant decrease in the levels of serum alanine, aspartate aminotransferases, glucose, and cholesterol compared to the J1 groups. Moreover, the J4 and J5 fish showed a significant decline in the levels of MDA with improvements in antioxidant (SOD, CAT, and GPX) and immunological (lysozyme, immunoglobulin M, and complement C3) indices compared to the J1 group. Fish in J4 and J5 exhibited downregulated levels of il-8, il-10, il-1β, tnf-α, ifn-γ, and hsp70 genes compared to other groups. In contrast, hepatic catalase (cat), superoxide dismutase (sod), and interleukin (il-10) gene expressions were upregulated. The lowest fish mortality after the bacterial challenge was recorded in the J5 group. These findings suggest that 2.0 g/kg feed ethanolic extract of J. communis-fed Tilapia fish fingerlings improved their growth and intestinal health, boosted their immune systems and antioxidant responses, and increased their resistance to A. hydrophila. [ABSTRACT FROM AUTHOR]

Aquaculture and the production of aquatic goods are rapidly growing industries in the world. These industries involve the cultivation of various saltwater and freshwater fish as well as shellfish species, and they undergo regular updates in their manufacturing processes. The increasing popularity of aquaculture is driven by the desire to achieve long-term sustainability in food production. However, the intensification of farming techniques can lead to economic losses due to fish mortality, which is often caused by infectious and stressful conditions. To address this challenge, it is crucial to enhance the immune response of fish as part of sustainable intensification and aquaculture management. Recently, there has been growing interest in eco-friendly and natural bioactive solutions as potential alternatives to synthetic compounds used for disease prevention in aquaculture. Medicinal plants, available as whole plants, plant extracts, or synthetic analogues of natural substances known as phytomedicines or phytopharmaceuticals, have shown high efficacy in disease prevention for humans and animals. One such medicinal plant is Saussurea lappa, which is extensively utilized in various forms of medicine for treating multiple diseases. The bioactive chemicals derived from S. lappa exhibit a wide range of biological activities, including anti-inflammatory, antioxidant, antimicrobial, and anticancer properties, along with immunostimulatory effects. Given the diverse biological activities of S. lappa and its potential to enhance the immune responses of aquatic species, this review focuses on exploring its contributions in this area. By examining the numerous benefits and applications of S. lappa, we aim to shed light on its potential role in improving the immune response of aquatic species. [ABSTRACT FROM AUTHOR]

Ecosystems and biodiversity across the world are being altered by human activities. Habitat modification and degradation are among the most important drivers of biodiversity loss. These modifications can have an impact on species behavior, which can, in turn, impact their mortality. While several studies have investigated the impacts of habitat degradation and fragmentation on terrestrial species, the extent to which habitat modifications affect the behavior and fitness of marine species is still largely unknown, particularly for pelagic species. Since the early 1990s, industrial purse seine vessels targeting tuna have started deploying artificial floating objects—Drifting Fish Aggregating Devices (DFADs)—in all oceans to increase tuna catchability. Since then, the massive deployment of DFADs has modified tuna surface habitat, by increasing the density of floating objects, with potential impacts on tuna associative behavior and mortality. In this study, we investigate these impacts for yellowfin tuna in the Indian Ocean. Using an individual‐based model based on a correlated random walk and newly available data on DFAD densities, we quantify for the first time how the increase in floating object density, due to DFAD use, affects the percentage of time that yellowfin tuna spend associated, which, in turn, directly impacts their availability to fishers and fishing mortality. This modification of tuna associative behavior could also have indirect impacts on their fitness, by retaining tuna in areas detrimental to them or disrupting schooling behavior. Hence, there is an urgent need to further investigate DFAD impacts on tuna behavior, in particular, taking social behavior into account, and to continue regulation efforts on DFAD use and monitoring. [ABSTRACT FROM AUTHOR]

Robust projections of future trends in global fish biomass, production and catches are needed for informed fisheries policy in a changing climate. Trust in future projections, however, relies on establishing that models can accurately simulate past relationships between exploitation rates and ecosystem states. In addition, historical simulations are important to describe how the oceans have changed due to fishing. Here we use fisheries catch, catch‐only assessment models and effort data to estimate regional fishing exploitation levels, defined as the fishing mortality relative to fishing mortality at maximum sustainable yield (F/FMSY). These estimates are given for large pelagic, forage and demersal fish types across all large marine ecosystems and the high seas between 1961 and 2004; and with a 'ramp‐up' between 1841 and 1960. We find that global exploitation rates for large pelagic and demersal fish consistently exceed those for forage fish and peak in the late 1980s. We use the rates to globally simulate historical fishing patterns in a mechanistic fish community model. The modeled catch aligns with the reconstructed catch, both for total catch and catch distribution by functional type. Simulations show a clear deviation from an unfished model state, with a 25% reduction in biomass in large pelagic and demersal fish in shelf regions in recent years and a 50% increase in forage fish, primarily due to reduced predation. The simulations can set a baseline for assessing the effect of climate change relative to fishing. The results highlight the influential role of fishing as a primary driver of global fish community dynamics. Plain Language Summary: Fishing can heavily impact the number and types of fish in a region. Yet, simulating the historical impacts of fishing on fish communities is challenging, especially on a global scale. This is because for many places, we do not know how many fish are in the sea and what fraction of these fish die from fishing each year. In this study, we estimated the historical rate by which fisheries have caught fish globally. We used these data in a mathematical model to simulate the number of fish in the sea; both with and without fishing. The model shows that fishing has reduced the biomass of big predators (large pelagic and demersal fish) by 25% in shelf regions. This decline led to less predation on forage fish and a 50% increase in forage fish biomass, despite fishing of forage fish. These simulations will allow estimating the relative effects of climate change and fishing on current and future fish communities. Key Points: We estimated global gridded fishing exploitation patterns for large pelagic, forage and demersal fish types using catch and effort dataFood‐web simulations with reconstructed fishing exploitation rates broadly replicated catch trends of diverse ecosystems on a global scaleGlobal biomass declines due to fishing of large pelagic and demersal fish leads to increases in forage fish via a trophic cascade [ABSTRACT FROM AUTHOR]

Cypermethrin, a Class II pyrethroid pesticide is well-documented for its toxicity to non-target organisms. Its environmental breakdown and the resulting harmful effects in various species have been widely researched because of its high toxicity. In this context, the present study aimed to evaluate the acute toxicity of cypermethrin (25% EC) on juvenile Cyprinus carpio, var. communis. Juvenile fish, each weighing 12±2 grams were used for the study. Initial range-finding tests were followed by definitive tests, and the acute toxicity data was analyzed using Finney's Probit Method. The 96-hour LC50 for Cyprinus carpio was determined to be 1.239 µg/L in a static bioassay setup. The mean values of the physicochemical parameters of the aquarium water measured during the bioassay showed slight variations, indicating that fish mortality was due to pesticide exposure rather than suffocation. The average laboratory temperature was recorded at 17°C, while the water temperature was measured at 12°C. The mean dissolved oxygen levels were 6 mg/L and the pH was 7.5. Total dissolved solids were 4.0 × 10³ mg/L and CO2 levels remained constant at 1.2 mg/L. [ABSTRACT FROM AUTHOR]

Fish farming is increasingly important globally and nationally, playing a crucial role in fish production for human consumption. Monitoring microbiological and chemical contaminants from water discharge is essential to mitigate the risk of contaminating water and fish for human consumption. This study analyzes the physicochemical and E. coli parameters of water and tambacu fish muscles (Colossoma macropomum × Piaractus mesopotamicus) in Western Maranhão, Brazil. It also includes a qualitative characterization of zooplankton in the ponds. Samples were collected from tambacu ponds in a dam system fed by natural watercourses from the Tocantins River tributaries, located at the connection of the Brazilian savanna and Amazon biomes. The physicochemical and E. coli parameters of water did not meet national standards. The zooplankton community included Rotifera, Cladocera, Copepoda, and Protozoa representatives, with no prior studies on zooplankton in the region, making these findings unprecedented. The biological quality of freshwater is crucial in fish farming, as poor quality can lead to decreased productivity and fish mortality, raising significant food safety concerns. The water quality studied is related to the potential influence of untreated wastewater as a source of contamination, leaving the studied region still far from safe water reuse practices. The findings on chemical and E. coli contamination of fish farming waters concern human health and emphasize the need for appropriate regulations. [ABSTRACT FROM AUTHOR]

The Atlantic tripletail (Lobotes surinamensis) is a high revenue-generating fish species predominantly caught by mechanized artisanal fishers community and the most available member of its family in Bangladesh. This is a ground work of fish stock assessment study in the Bay of Bengal region to explore the life history parameters and associated biomass of this species, using three length-based approaches of TropFishR, the length-based Bayesian biomass estimation (LBB), and Froese's length-based indicators (LBIs). An almost homogenous body growth pattern (b=3.07; R2=0.98) was observed in the length-weight relationship of tripletail. The life history parameters for tripletail, as determined by the von Bertalanffy Growth Function (VBGF) model, were L∞=113.36 cm and k=0.51/a. The length converted catch curve (LCCC) yielded an estimation of the total mortality (Z=1.77/a), with the natural mortality estimated at (M=0.53/a) and the fishing mortality estimated at (F=1.24/a). But, the ratio of mortality (F/M=0.15) by LBB captured the non-fully exploited status of biomass (B/BMSY=2.1). LBI analysis indicated that the tripletail fishery's spawning stock biomass is greater than the target and limit reference points, indicating a healthy state of biomass. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive assessment of the black-barred halfbeak (Hemiramphus far) in Bardawil Lagoon, North Sinai, Egypt, focusing on key parameters such as length at first capture, growth metrics, mortality rates, and relative yield per recruit. Data were collected monthly from May to December 2022, comprising a total of 1,593 fish samples from commercial catches in the lagoon. The fish that were sampled ranged in length and weight from 17 to 36.7cm and 22 to 247.3g, respectively, with an average of 23.84cm and 85.67g. The formula for the length-weight relationship of the studied species was W = 0.0029 TL 3.2286. This study showed four age groups. The estimated von Bertalanffy growth parameters were L∞ = 37.8cm and k = 0.48 year-1. It was found that the growth performance index (Φ ') was 2.84. An estimate of the length at first capture was 20.89cm. The length at first capture was determined to be 20.89cm. The mortality rates were calculated as follows: total mortality (Z) at 2.15, natural mortality (M) at 0.95, and fishing mortality (F) at 1.2 year-1. The exploitation rate (E) was found to be 0.56, indicating overfishing and high fishing pressure on the population. The relative yield per recruit analysis (Y'/R) showed that the current exploitation level significantly exceeds the sustainable threshold (E0.5=0.383). To sustainably manage this resource, the current exploitation rate needs to be reduced by 32%, decreasing from 0.56 to 0.383. The findings from this investigation are critical for the assessment and management of the H. far fishery in Bardawil Lagoon, ensuring the sustainability of this important fish species. [ABSTRACT FROM AUTHOR]

The present study aimed to assess the stock of Chloroscombrus chrysurus in the Ivorian coastal waters to support its sustainable management. Approximately 2,520 specimens were collected between July 2022 and June 2023. The fish were captured using beach seines and gillnets, then measured and weighed to the nearest millimeter and gram, respectively. Stock assessment was conducted using the Fisat software, which analyzed pooled length-frequency data. The estimated growth parameters for Chloroscombrus chrysurus were as follows: asymptotic length (L∞) of 22.05cm, growth rate (K) of 0.82 year-1, growth performance index (Φ') of 2.59, theoretical age (t0) of -0.084 years, and life-span (Tmax) of 3.57 years. Instantaneous fishing mortality (F) was estimated at 0.81 year-1, while natural mortality (M) was 1.70 year-1. The exploitation rate (E) was 0.32. The length at first capture (Lo50) was 13.32cm, which is slightly lower than the length at first sexual maturity (13.42cm). The findings indicate that the Chloroscombrus chrysurus population in Côte d'Ivoire's coastal waters is at moderate risk of overexploitation. To mitigate this risk, it is crucial to monitor the fishery and to implement immediate measures, such as increasing the mesh size of the nets and the cod-end or bag of beach seines. [ABSTRACT FROM AUTHOR]

The study on Bronze Featherback in Huai Kho Reservoir examined 273 specimens, with fork lengths ranging from 105 to 295mm and an average length of 185.80 ± 27.05mm. The fish exhibited a strong length-weight correlation, with an allometric coefficient (b) greater than 3.00, indicating a positive allometric growth. Growth parameters included an asymptotic length (L∞) of 309.75mm and a growth coefficient (K) of 0.10. Capture probabilities were 108.99 (L25%), 186.52 (L50%), and 191.44mm (L75%). Mortality rates were measured with a total mortality rate (Z) of 1.07 per year, natural mortality (M) at 0.22 per year, and fishing mortality (F) at 0.86 per year. Recruitment peaks occurred from June to August, and replacement rates were the highest from July to September. The current exploitation rate (E) of 0.80 exceeds the maximum sustainable rate (Emax) of 0.724. The total steady-state biomass was 10.57 tons. To promote sustainable management, it is recommended to regulate fishing gear and enforce a fishing ban during the spawning season. [ABSTRACT FROM AUTHOR]

Two of the most-commonly used pyrethroid insecticides were subjected to static bioassays to determine their acute toxicity to Clarias gariepinus fingerlings, followed by comparisons of their impact on mortality and behavioural changes in the fish. The LC50 values for deltamethrin (DMT) at exposure durations of 24, 48 and 96 h were 12, 9 and 8 µg l−1, respectively; the LC50 values for cypermethrin (CYP) at the same exposure durations were 55, 44 and 26 µg l−1, respectively. The estimated safe limits ranged from 8×10−1 to 8×10−5 µg l−1 for DMT, and 26×10−1 to 26×10−5 µg l-1 for CYP. The tested substances had an acute toxicity effect on fish development as they caused death, and chronic toxicity effects as they changed fish behaviour. Fish exposed to either one of these pesticides showed behavioural alterations, such as loss of static balance, excessive mucous secretion, irregular swimming, gulping of air and skin discolouration. The results reveal that CYP was less toxic (96-h LC50 = 26 µg l−1) than DMT (96-h LC50 = 8 µg l−1) based on the greater LC50 value and a lower percentage of mortality. To avoid potential ecotoxicological risks to aquatic life, use of these pyrethroids in both terrestrial and freshwater ecosystems must be treated with caution. [ABSTRACT FROM AUTHOR]

The adequate collection of health information at the farm level is the first step in good health management. The objective of this study was to analyze how Spanish fish farms collect their census, disease occurrence, and mortality data through their farm record books and how they use them for reporting to competent authorities. Comparing and contrasting farm books between regions (autonomous communities) revealed a lack of standardization and substantial differences in the reporting. Therefore, this study points out the need to improve and standardize, at the national level, the design of fish farm record books in order to ensure the better collection of farm census data on mortality and disease occurrence, which may facilitate the production of epidemiological reports and the early detection of emerging diseases at the national level. [ABSTRACT FROM AUTHOR]

Twelve commercial species exploited in the eastern Guangdong and southern Fujian waters were assessed using the Catch-Maximum Sustainable Yield (CMSY) and Bayesian Schaefer Model (BSM) methods. The carrying capacity (k), intrinsic rate of population growth (r), maximum sustainable yield (MSY), and relative biomass (Bend/k and B/BMSY) were estimated. The current stock status was defined by B/BMSY and fishing mortality (F/FMSY). The results indicate that seven stocks were overfished or below safe biological limits (B/BMSY < 0.5 or F/FMSY > 1), two stocks were in a recovery phase (0.5 < B/BMSY < 1, F/FMSY < 1), and three stocks were under sustainable fishing pressure with healthy biomass, capable of producing yields close to the MSY (B/BMSY > 1, F/FMSY < 1). The stock statuses are consistent with previous studies on the utilization of pelagic fisheries in the eastern Guangdong and southern Fujian waters and with those assessments in other waters. The results of the assessments suggest that these stocks could be expected to produce higher sustainable catches if permitted to rebuild; thus, more effective and proactive management is needed in this upwelling fishing ground. [ABSTRACT FROM AUTHOR]

Freshwater fisheries in developing regions provide livelihoods and nutrition for millions of people worldwide. These fisheries are frequently data poor, which limits fisheries management. The seasonal Cambodian dai platform fishery on the Tonle Sap River is one of the best monitored inland fisheries in Southeast Asia, yet catch sampling is limited and there is no fishery-independent monitoring. A monitoring system is needed to characterize fish migration and mortality, be cost effective, and be deployable in areas with minimal infrastructure. We integrated a Simrad wide-band transceiver mini echosounder (200 kHz), solar power, and an Internet of Things communications module as an autonomous, automated monitoring package for the deployment on upstream and downstream commercial fishing platforms. The solar panel and controller supply direct current power to the echosounder, communications module, and battery for power during dark hours. Echosounders are programmed to sample at 1 Hz for 15 min every hour. The communications module is a built cellular endpoint that accesses a local wireless network to transmit raw data files to a data server. Data are downloaded from the server for processing and analysis. This expandable system provides a flexible management tool that can be deployed at any location with wireless communication capability. [ABSTRACT FROM AUTHOR]

Maximum sustainable yield reference points (MSY-RPs) are usually calculated assuming spawner-recruitment relationships (SRR) and population dynamics of the stock. However, due to the difficulty of estimating SRR, the uncertainty in MSY-RPs is often too large to be put into practice. Therefore, based on the concept of maximum–minimum yield (MMY), fishing mortality (F) that gives %SPR (spawner biomass per recruitment [SPR] at a given F relative to SPR in the absence of fishing) of 30–50% (F30-50%SPR) is often used as a proxy of FMSY (F that maximizes the long-term catch). In this study, we estimated F % SPR MMY (F expected to produce %SPR at MMY) for 30 stocks of Japanese fishery resources based on the life-history parameters of the stocks and steepness assumptions derived from meta-analysis. Our results showed that %SPRMMY ranged from 23% to 62% (excluding 86% of Scomberomorus niphonius), depending on the stock and the assumed steepness scenario. If the fish were caught under F % SPR MMY , at least 70% of the MSY could be expected in Japanese fishery resources. When compared with the %SPRMSY for the 15 stocks estimated through Japanese fishery stock assessment, %SPRMMY were similar, or often larger. %SPRMMY can be considered a precautionary value, reflecting the uncertainty of SRR. [ABSTRACT FROM AUTHOR]

Most fisheries are conducted without any scientific knowledge about the size and productivity of the stocks that support them. This navigation in the dark in most fisheries is a major obstacle in making them sustainable sources of nutrition for people in general and income for fishers and other economic actors along supply chains. Fisheries that have not been assessed generally are data‐intermediate and data‐poor, the latter usually having annual time series of landings as the single piece of data available. A major effort in the last two decades has been directed toward developing 'catch‐only' stock assessment methods, although some of these methods have been tested and found deficient. Here we provide a novel approach to using annual landing time series as the single source of data to qualitatively judge the condition of un‐assessed stocks using frequentist cumulative probability ogives, both in terms of stock biomass and fishing mortality. A meta‐analysis of the FishSource database allowed us to infer statistical patterns from hundreds of assessed fisheries and thousands of annual landings, biomass, and fishing mortality observations. Four stock‐management types were considered separately in the analysis: short‐lived and others (mid‐ to long‐lived) stocks, controlled or not controlled by catch limits. Obtained cumulative probability ogives provide clear evaluations of stock biomass and fishing mortality trends in all four stock‐management types, leading to actionable information on probable current status and future trends. Using these probability ogives, we developed decision trees that lead to qualitative scores on the exploitation status of un‐assessed stocks. [ABSTRACT FROM AUTHOR]

The study on which this article reports argued that illegal fishing activities in the Namibian territorial waters and exclusive economic zones have implications for maritime security. The study traced the problem of illegal fishing in the country back to colonial times and linked it directly to foreign vessels. The intrusion of foreign vessels into Namibian waters received little interest – or if at all – in terms of the protection of ocean resources by the colonial administration coupled with a lack of regulatory frameworks. It was noted that the pattern of illegal fishing established during colonial times has continued into the present with several consequences. Illegal fishing affects maritime security in Namibia in five main dimensions, namely projection of military power at sea, protection of the marine environment, economic growth, development, and human security. These dimensions of maritime security are integrally linked and mutually reinforcing. It was thus shown that the limitation of sea patrols by the Namibian Navy and the Ministry of Fisheries and Marine Resources due to financial constraints caused by illegal fishing activities has a negative influence on the marine environment in terms of destruction and depletion of fish resources. Depletion of fish stocks results in loss of revenue and loss of jobs for coastal community dwellers. Combating illegal fishing is necessary if the marine resources are to be protected and make a significant contribution to the Namibian state. To combat the challenge of illegal fishing, improvement and strengthening of existing mechanisms, international collaboration, cooperation, and coordination between maritime security agencies, and continued engagement with neighbouring states were considered necessary. [ABSTRACT FROM AUTHOR]

Preventing fish entrainment during their downstream passage at hydropower plants remains a major challenge in reducing the ecological impacts of hydropower production. We investigated fish behavior at the world's first innovative shaft hydropower plant with its novel screen concept, aiming at reducing fish entrainment due to the fully horizontal arrangement of the screen and low vertical suction effects toward the turbine. Based on ARIS sonar recordings, we assessed whether fish could move unhindered across the turbine intake area toward the bypass corridors at the sluice gate for safe downstream passage. For a range of species (Anguilla anguilla, Barbus barbus, Thymallus thymallus, Salmo trutta, and Hucho hucho) and operation modes (high/low turbine load), we assessed behavioral patterns such as screen avoidance, dwelling behavior, and search behavior at the screen. Contrary to the engineers' expectations, the innovative screen arrangement neither guided the fish away from the turbine intake to the bypass corridors nor prevented them from swimming vertically into the turbine shaft. Rather, fish freely moved near the screen and avoidance behavior was only rarely observed. Both the dwelling and active search behavior, which was particularly evident in eel, are directly linked to an increased risk of screen passage and subsequent turbine‐related death or injuries. Our findings illustrate that consideration of fish behavior at turbine inlet structures is a crucial component which needs to be integrated with other variables such as fish mortality and injury patterns for a comprehensive evaluation and improvement of fish passage at hydropower plants. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of polypropylene (PP) microplastics on the growth performance, hematological profile and oxidative stress responses in the liver and brain tissues of Oreochromis niloticus juvenile. The microplastic exposure was done by offering microplastic‐incorporated feed to the fish. The feed was prepared by mixing microplastics and the feed in three different ratios; Low (1.5 g/kg), Medium (3.0 g/kg), High (4.5 g/kg), and a control with no plastics in it. The trial was done for 7 weeks. A significant impact on the growth performance of the fish was observed in terms of body weight gain, specific growth rate, metabolic growth rate, protein efficiency ratio and energy retention. All the treatments had a significant difference in growth parameters compared to the control. The results of the hematological profile confirmed erythropoietic impairment in the fishes due to high microplastic exposure which led to an anemic condition in the fishes and mortality in the early juvenile stage. The antioxidant enzyme analysis also shows significant oxidative stress induced in liver and brain tissues in a dose‐dependent manner. Exposure to PP microplastics significantly affected the growth, health and metabolism of O. niloticus. Further studies on genetic and cellular levels should be done to elucidate the wide‐ranging effects of MPs on fish species. [ABSTRACT FROM AUTHOR]

The knowledge of the life-history traits of commercial and data-deficient fish species is essential for assessing, among others, their status, as well as for the formulation of conservation measures and the implementation of sustainable managerial decisions. In the present study, growth parameters were estimated for eight fish species of the Lake Trichonis (Greece): Atherina boyeri, Cobitis trichonica, Leucos panosi, Luciobarbus albanicus, Rhodeus meridionalis, Salaria economidisi, Scardinius acarnanicus and Tropidophoxinellus hellenicus. The mortality and exploitation status were estimated for the five most exploited ones (A. boyeri, L. panosi, L. albanicus, S. acarnanicus and T. hellenicus). For four of the abovementioned species (C. trichonica, R. meridionalis, S. economidisi and T. hellenicus), life history data were provided for the first time. A. boyeri (a commercially important and the most exploited species in the lake) and T. hellenicus (a discarded species) exhibited the highest values of fishing mortality, followed in descending order by L. albanicus, L. panosi and S. acarnanicus. The information produced in the present study can be incorporated in ecosystem-based models aiming at the establishment of management and conservation measures at both species level and ecosystem level. [ABSTRACT FROM AUTHOR]

Aquaculture has emerged as a pivotal alternative for seafood production, addressing the challenges posed by depleting wild fish stocks. However, the industry faces substantial challenges, notably the presence of harmful algal blooms (HABs), which can cause serious economic consequences. The proliferation of major species of phytoflagellates leading to massive fish mortality is on the rise, possibly attributed to increasing global temperatures and eutrophication. This underscores the critical need for robust detection, prevention, and mitigation strategies to safeguard the aquaculture industry. This contribution offers valuable insights into comprehending and addressing the challenges posed by HABs in the fish aquaculture sector in an era of global change. [ABSTRACT FROM AUTHOR]