ABSTRACT Marine fish parasites threaten both aquaculture sustainability and food safety and have been studied for more than 200 years with more than 10,000 papers. However, there has been no systematic summary of this area in recent years. A total of 11,368 research papers on marine fish parasites were collected from Web of Science (WoS) and Scopus. On the basis of bibliometrics, the output of research achievements, contributions from countries/regions, institutions and authors, as well as their collaborative relationships, core journals, highly cited papers and references, were analysed. The evolutionary trends in research themes within this field were also explored. Emerging countries, institutions and scholars continue to appear in the study of marine fish parasites, and new achievements have been made in such fields as parasitology, genetics and marine ecology. The immune mechanisms, disease monitoring and vaccine development for parasitic diseases in commonly farmed fish species are key areas of focus for researchers in the coming period. This article provides a comprehensive portrait of marine fish parasite research, which is helpful for researchers to determine the research theme and choose partners and publications. The research limitation is that inconsistencies in data from different sources result in slight deviations in the analysis results.

Sexual reproduction is ancient and ubiquitous despite its obvious disadvantages1. Theory predicts that the reassortment of alleles that results from sex is necessary for natural selection to act effectively on individual loci; therefore, a purely clonal organism should rapidly accumulate deleterious mutations and go extinct2-4. Nevertheless, many asexual species have existed for longer than theory predicts is possible5-7, such as the Amazon molly (Poecilia formosa), a clonally reproducing fish arising from a single hybridization event more than 100,000 years ago8-10. Here we show that although the Amazon molly has accumulated mutations faster than its sexual progenitor species, this has not led to functional mutational decay, defying theoretical expectations. Instead, gene conversion facilitates both adaptive and purifying selection by generating new clonal lineages in which previous mutations are either reverted or fixed, and by resolving hybrid incompatibilities between the ancestral haplotypes. The transition to clonality altered chromatin structure, but the asexual haplotypes of the Amazon molly nonetheless maintain the divergent mutational landscapes of their progenitor species. Together, these results provide new insights into long-standing questions about the trade-offs involved in asexual reproduction.

Stiffness exerts a significant influence on swimming locomotion of fish. Biological experiments have demonstrated that the stiffness of different body segments in fish is inherently heterogeneous. Although the stiffness variation patterns from head to tail exhibit certain interspecific differences among various fish species, they generally follow a decreasing trend from anterior to posterior. In this study, based on the resistive drag model, we discretized the original model and incorporated improvements such as the distribution function of active bending moments. The analytical model developed herein integrates the stiffness distribution of the fish body into the analysis of its locomotion. Through this model, several typical stiffness distribution patterns were investigated, with a particular focus on sub-topics such as various decreasing distributions and the effects of different segment quantities. The results indicate that a rapidly decreasing stiffness distribution with a low ratio of minimum-to-maximum stiffness yields the optimal swimming performance. This work serves not as a substitute for but rather a supplement to pertinent biological experiments. Simultaneously, it constitutes a foundational study for variable-stiffness distribution robotic fish, informing and guiding future design endeavors.

ABSTRACT Ferrazo (Vilagarcía de Arousa, Pontevedra, Spain) – in the northwest of the Iberian Peninsula – is a complex Roman site originally located on the seashore including a cetaria (fish-salting factory). The extremely good preservation of this site offered the possibility of enlarging our current knowledge about fish-salting production in northwest Iberia, where these productive sites dedicated to marine resource exploitation were frequently established along the coastal areas during the Roman Period. We present the archaeological excavation record and the results of a multidisciplinary analysis after systematic sampling of a salting vat content. Our multidisciplinary approach combines ichthyofaunal studies, scanning electron microscopy Energy Dispersive X-Ray Spectroscopy (SEM-EDX), conventional analytical pyrolysis (Py-GC-MS), thermally assisted hydrolysis and methylation (THM-GC-MS), archaeobotanical analysis, and AMS radiocarbon dating. Sardina pilchardus is the almost exclusive fish species preserved within the vat involved in fish-salting, which were processed entirely, in accordance with ichthyofaunal remains and chemical markers. The presence of fragments of charred wood might be related to the addition of wood ash during the production process.

ABSTRACT Objective Determine the 48-h acute toxicity of copper sulfate (CuSO4) to freshwater fish and snail species economically important to aquaculture in reconstituted waters ranging from “very soft” (low alkalinity/hardness/pH) to “very hard” (high alkalinity/hardness/pH). The 10 fish species studied were Channel Catfish Ictalurus punctatus, Golden Shiner Notemigonus crysoleucas, koi (a variant of Amur Carp Cyprinus rubrofuscus), Largemouth Bass Micropterus nigricans, Nile Tilapia Oreochromis niloticus, Rainbow Trout Oncorhynchus mykiss, Striped Bass Morone saxatilis, sunshine bass (female White Bass Morone chrysops × male Striped Bass Morone saxatilis), Walleye Sander vitreus, and White Bass Morone chrysops. Additional experiments examined CuSO4 toxicity in ghost rams-horn Biomphalaria havanensis and marsh rams-horn Planorbella trivolvis, which serve as intermediate hosts to parasites in many industry-relevant fish species, including those used in this study. Methods Acute toxicity of CuSO4 was determined during 48-h exposures to six nominal concentrations in each of the five reconstituted waters ranging from very soft to very hard. Bioassays were performed at water temperatures relevant to individual species (14–23.2°C). The lethal concentration to 50% of the population (LC50 values) and the No Observed Effect Concentration were determined for each species and reconstituted water combination. Results Using comparisons of the CuSO4 LC50 values to each species in the five reconstituted waters during separate bioassays, we determined that Rainbow Trout are most sensitive to CuSO4 compared with the least sensitive species, Channel Catfish, Nile Tilapia, and particularly Largemouth Bass. The No Observed Effect Concentration values would be considered the safe range for aquaculturists to use CuSO4 in a particular water type with a particular species. Snail species did not have similar trends or susceptibility to Cu (as CuSO4) as alkalinity increased. The CuSO4 toxicities were negatively correlated with temperatures. Conclusions These data benefit aquaculture producers when investigating treatments in various local waters or modeling by environmental scientists.

ABSTRACT Small pelagic fish and other forage species are patchily distributed over space and time, resulting in variable foraging conditions experienced by their predators. The high‐resolution data necessary to understand the spatiotemporal structure of forage communities are challenging to collect with expensive fishery‐independent surveys, meaning that other, complementary approaches are needed. To fill this gap, we partnered with recreational anglers to sample the stomach contents of more than 2500 adult Chinook salmon ( Oncorhynchus tshawytscha ) throughout the Canadian Salish Sea in both summer and winter from 2017 to 2022. Previous studies found that the diet composition of adult Chinook salmon correlated well with conventional indices of forage species abundance, meaning that Chinook salmon diets can be used to understand the availability and distribution of their prey. Cluster analysis of Chinook salmon diet composition identified regions with distinct forage communities in the Salish Sea. Regions were distinguished from one another by the elevated importance of only one or two forage species. Pacific herring ( Clupea pallasii ) were key prey in all regions and throughout the year, while the importance of other forage species including Pacific sand lance ( Ammodytes personatus ), northern anchovy ( Engraulis mordax ), myctophids, and mysids was spatially and (or) seasonally restricted. The regional structure of Salish Sea forage communities was associated with static and dynamic oceanographic processes, such as bathymetric features, tidal mixing, and freshwater input. Predator diets can provide novel insights into the ecology of their prey, supplementing fishery‐independent surveys to support ecosystem approaches to fisheries management.

The Indian mackerel (Rastrelliger kanagurta) is a commercially important fish species in Bangladesh. This study was conducted by using two catch-based methods, Depletion-Based Stock Reduction Analysis (DB-SRA) and Catch-Maximum Sustainable Yield (CMSY), to determine stock status with length-based approaches to update the life-history estimates of Indian mackerel stock. Sensitivity tests and projection were also performed to find out how well the models predicted the estimates at different input parameter's value and evaluate catch strategies. The life-history parameters were estimated as L∞=33.25cm and k = 0.92 year- 1. The fishery experienced a sudden increase in its landings to the abnormally highest point in 2012, followed by a state of equilibrium. However, the current spawning potential ratio (SPR) of 17% indicated a concerning sign regarding stock spawning capacity, where over 50% of catches were observed to be below the maturity level. This study suggests an optimum length limit of 18-22cm to adjust the growth and recruitment overfishing. Hence, an annual catch limit of 1500 mt is recommended for the next 15 years under the maximum sustainable yield (MSY) reference bar (1967 mt), in convergence with the annual fishing ban, to gradually maintain the current overfished biomass of Indian mackerel approaching the BMSY level. Besides, the dynamic, transboundary nature of the Indian mackerel demands both national action and international cooperation for better management.

ABSTRACT The duration, magnitude, and frequency of heatwaves are predicted to increase in the coming decades, a combination that can reduce the survival of many fish species. Across the world, there is broad interest in identifying thermal refuge for heat‐intolerant fish species and exploring opportunities to enhance or protect these areas. Because deeper groundwater maintains a relatively constant temperature, groundwater‐influenced areas along streams can provide cool‐water refuge for fish during periods of extreme heat. A targeted approach was developed for identifying existing cold‐water zones and areas of substantial groundwater discharge in four high priority Lake Ontario tributaries. Our approach included: (1) predicting where groundwater discharge is most likely with a simple geospatial model and (2) using model predictions to select field sites for intensive high‐resolution study, including ground‐based mapping of groundwater features (springs, seeps, tributaries) as well as drone‐based optical and thermal infrared surveys. Results from field sites were used to both verify model performance and map different types and aerial extents of thermal anomalies. Geospatial modelling successfully predicted regions of widespread groundwater upwelling, later verified and mapped by field and drone surveys. Comparison of model and field survey results further highlighted specific geospatial layers, such as soil/bedrock types and topographic wetness index, as being particularly useful for predicting groundwater influence on streams in the study area. In addition, a comparison of geospatial model results with a model of fish abundances along the studied streams showed significant positive correlations for many heat‐intolerant fish species over a wide geographic area. The approach developed in this study can be applied to other watersheds to highlight areas of probable groundwater discharge and could be used by fishery and water resource managers to support cold‐water fish habitat management decision‐making and resource conservation.

Deriving predicted no-effect concentrations for PFASs to protect threatened and endangered fish: A comparison of water- andtissue-residue-based toxicity data.

Local environmental changes boost predation risk in forage fish: application to the sand lance in the eastern Seto Inland Sea.

Multi-scale analysis of thermal processing-induced textural changes in fish muscle with distinct ecological characteristics: Integration of structural and proteomic perspectives.

Revealing nutritional value and metal(loid)s and minerals in fish species in Çıldır Lake, Türkiye: assessment of risks to human health, fish gender and size-relevant difference.

Structural features of collagens of warm-blooded and cold-blooded animals that determine differences in their thermal stability.

In Bhoj Wetland, Bhopal, the presence of microplastics (MPs) in fish and water was investigated in both wet and dry seasons. Microplastic concentrations ranged from 10 ± 4 to 19 ± 4 items L-1 during the dry season and 8 ± 1 to 15 ± 8 items L-1 during the wet season. Among fish species, Wallago attu and tilapia showed average MP loads of 1.2 ± 1.10 and 0.8 ± 1.30 items per individual, respectively. Due to sewage, hospital waste, and tourism, higher MP levels were discovered during the dry season, particularly along Sultania Road (L1) and Masjid Lal Imli (U3). MP presence was quite low in central lake zones. Among the various shapes identified, fibers emerged as the dominant type in both aquatic samples and fish tissues. Wallago attu and tilapia showed the highest MP content, mostly made of polyethylene (PE). The predominance of black and transparent microplastic particles suggests their probable origin from degraded fishing equipment and general plastic litter. Seasonal changes influenced MP levels, with higher amounts in dry months due to less water flow and dilution. The study highlights the impact of human activities and the need for better pollution control.

Does telencephalic lateralization modulate anxiety? Effects of unilateral ablation assessed in the light-dark and open field tests in Nile tilapia (Oreochromis niloticus).

Selenium and mercury tissue partitioning and trophodynamics in the Lake Koocanusa (USA-Canada) fish community.

Pampus species play a significant role in offshore food webs and are regarded as representative economically important fish. Owing to variations in their geographical distribution, distinct differences in feeding habits exist among pomfret species. However, the presence of an esophageal sac in pomfrets complicates accurate identification of their dietary composition through conventional stomach content analysis. Consequently, research on the feeding ecology of pomfrets remains limited and imprecise. This study employed environmental DNA (eDNA) high-throughput sequencing technology to analyze the composition and relative abundance of gastric contents in three Pampus species (P. argenteus, P. punctatissimus, and P. cinereus) collected from Qingdao, Shandong Province and Wenchang, Hainan Province. Key findings include: (1) Analysis revealed 21, 7, and 2 fish species in the gastric contents of P. argenteus, P. punctatissimus, and P. cinereus respectively, with anchovy (Engraulis japonicus) demonstrating the highest relative abundance in the former two species, while Thryssa hamiltonii predominated in P. cinereus. (2) Crustacean communities comprised 49, 42, and 26 species across the respective species, constituting over 60% of total identified taxa and indicating their trophic importance. Acetes japonicus exhibited maximal relative abundance in P. argenteus and P. punctatissimus, whereas Acetes chinensis dominated in P. cinereus. (3) Cephalopod analysis identified 8 and 6 species in P. argenteus and P. punctatissimus respectively, with Loligo beka and Sepiola birostrata showing peak abundance in each species, while no cephalopod species were detected in P. cinereus. Comparative analysis with traditional dissection methods and stable carbon-nitrogen isotope techniques confirmed crustaceans as the most diverse dietary component across Pampus species. This investigation demonstrates the efficacy of eDNA metabarcoding for elucidating feeding ecology in Pampus spp., providing critical insights into their trophic interactions and ecological significance within marine food webs.

Synergistic effects of metal pollution and habitat degradation from artisanal gold mining drive species-specific oxidative stress and biodiversity loss in a semi-arid river catchment.

Brain proteomics of rainbow trout at certain maturation stages: biological insights and fish by-products processing perspectives.

Characterization of extracellular vesicles from primary skin epithelial cells and cell lines from Atlantic salmon.