Important Fish Species Research Articles

ANALYSIS OF TRADITIONAL FISHING IN THE BHITARKANIKA

Traditional fishing communities' livelihoods solely depend on the freshwater, estuary, brackish water, creeks and coastal areas abutting the Bhitarkanika National Park, Orissa India. Bhitakanika Mangrove ecosystems serve as vital nursery grounds for the economically important nearshore fish and shellfish species. The freshwater rivers, channels, creeks, salt marsh wetlands, and associated coastal waters are highly productive. The fishing community have been pressurised by the forest department to implement restrictions in the National Park Area to protect the sea turtles, crocodiles and other endangerous wild animals. In addition to the restrictions of the Forest Department, immigrated fishermen who are using advanced instruments, crafts and gears in capture fisheries reduce the fish stock distribution and diversity. The climate change impacts also influence the fish stock population, distribution, diversity and recruitment reducing the catch per effort of the traditional fishermen. In this research paper, traditional fishermen of the Bhitakanika National Park Area fishing population, fishery, fishing culture, livelihoods, various issues, and recommendations to find alternative employment opportunities to reduce fishing pressure in the Bhitarkanika National Park have been discussed.

An overview of the current status of Lake Jipe and its biodiversity dilemma

AbstractLake Jipe, is a shared water resource between Kenya and Tanzania located at the East African Coast is under multiple pressures. The present study assessed the current state of Lake Jipe and its biodiversity dilemma. Random sampling was conducted at 14 sampling points set at equidistant parallel to each other. Sampling depths and location coordinates were measured using Solar Transducer and GPSMAPS® 65 s. In situ water quality parameters were measured using YSI Pro Plus multiparameter; water samples for nutrients analysis were collected and preserved in cooler boxes prior transportation to Kenya Marine and Fisheries Research Institute (KMFRI) laboratory for analysis according to ALPHA 2005. Socio‐economic data in relation to status of Lake Jipe ecology were generated using Key Informants Interviews at identified beaches along Kenya and Tanzania. Present findings indicated that the lake has receded from the original 108.72 Km2 to 27.32 Km2 with annual temperatures, dissolved oxygen and conductivity of 28.58 ± 0.95, 5.19 ± 00 and 799.24 ± 69.41, respectively, for dry season. Wet season recorded 31.21 ± 0.31, 4.16 ± 0.01 and 882.44 ± 57.41 for temperature, dissolved oxygen and conductivity, respectively. Agricultural activities have significantly (90%) contributed to the lake levels decline and further affected the lakes' aquatic biodiversity. Among the most affected are the commercially important endemic fish species of the lake of which Oreochromis jipe has experienced the greatest decline. Overfishing, use of illegal unreported and unregulated fishing gears, intensified fishing along protected fish breeding areas as well as poor management and uncoordinated conservation efforts have significantly contributed to the decline of fish catches from 348 kg of O. jipe in 2016 to 90 kg daily catches in 2022. Consequently, the lake is in the verge of extinction if no action is taken. This calls for awareness on the significance of the L. Jipe ecosystems and its immediate and long‐term benefits. Further, there is need to revive and promote alternative economic activities including sustainable aquaculture and agriculture to local communities.

Impact of invasive seagrass Halophila stipulacea on life history characteristics of juvenile yellowtail snapper (Ocyurus chrysurus)

Seagrass ecosystems provide essential nursery habitat to numerous coral reef fishes. Native Caribbean seagrasses Syringodium filiforme and Thalassia testudinum provide several juvenile fish species with foraging habitat and protection during this vulnerable stage of life. In 2002, an invasive seagrass Halophila stipulacea was discovered off the coast of Grenada and has since rapidly spread throughout the Caribbean. Halophila stipulacea has been shown to displace native seagrass species and may pose additional threats to juvenile reef fish populations that depend on native seagrass habitats as nurseries. The purpose of this study was to determine the effects of H. stipulacea on the early life history of yellowtail snapper (Ocyurus chrysurus). Settlement, mortality, and condition of juvenile yellowtail snapper were compared among native and invasive seagrass habitats around southern St. Thomas, United States Virgin Islands. From May 2020 to June 2021, monthly surveys within fixed plots during new moon periods provided information on settlement rates and survivorship among seagrass types. Length and weight of 260 juvenile yellowtail snapper were measured to derive condition factor among seagrass species. Significantly higher settlement and similar trends in mortality were seen in H. stipulacea when compared to native seagrasses. No significant difference was observed in condition factor of juvenile yellowtail snapper among seagrass species, although trends demonstrated a higher condition in individuals from native seagrass species. This study is the first of its kind to identify the direct effects of H. stipulacea during the early life history stages of a commercially important fish species in the Caribbean.

Level of Heavy Metals in Fish and Associated Human Health Risk From the Omo Delta in Southern Ethiopia: A First-Hand Report.

This study was the first to investigate the levels of heavy metals in commercially important fish species (Lates niloticus and Oreochromis niloticus) and the human health risk in Southern Ethiopia. Sixty fish samples were collected from the Omo delta. The target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR) were used to estimate the human health risks. The mean levels of heavy metals detected in the liver and muscle of Lates niloticus generally occurred in the order of Fe> Zn > Pb > Cu >Mn> Cr > Co > Ni and Fe > Pb > Zn >Mn > Cu > Co > Cr >Ni, respectively. Similarly, the mean levels of iron in the muscle and liver tissues of Oreochromis niloticus were in the order of Fe > Pb > Zn >Mn> Cu > Cr > Co > Ni and Pb > Fe > Zn >Mn> Co > Cu > Ni, respectively. The THQs in the muscle of L. niloticus and O. niloticus decreased in the order Pb > Cr > Cu >Mn> Co > Zn > Fe> Ni and Pb >Mn> Co > Cu > Zn > Ni> Fe respectively. Pb had the highest THQ value in L. niloticus and O. niloticus, which were 0.61 and 0.409, respectively in adult. Similarly, Pb had noted that, L. niloticus and O. niloticus had the highest THQ values, at 0.87 and 0.58, respectively in children. The HI values due to consumption of L. niloticus muscle were 0.668 for adults and 0.942 for children. The mean concentrations of Pb and Cr in the tissues of L. niloticus and O. niloticus were above the FAO/WHO permissible limits. Consequently, investigating heavy metal pollution levels in fish and human health risks from the Omo delta is imperative for addressing environmental and public health concerns.

Содержание ртути в рыбе, выловленной ниже целлюлозно-бумажного комбината в Северной Двине

Subarctic Russian rivers tend to have swampy watersheds with a high content of hydro­gen ions and humic substances. These conditions are favourable for the formation of bioavail­able mercury. Thus, even background mercury concentrations can pose a danger to aquatic organisms. The Northern Dvina River attracts particular attention regarding mercury pollu­tion due to the presence of pulp and paper mills in the area. These mills have historically uti­lised mercury in their production processes. This study aims to analyse the mercury content in commercially important fish species living in the mouth of the Northern Dvina River. The content and distribution of mercury in tissue samples of various fish species were determined to provide insight into components of the mercury cycle in the study area. Lower mercury levels in pristine areas of the Russian subarctic showed the role of aquatic organisms as indicators of the biogeochemical cycle of mercury migration in northern freshwater areas. This study provides new scientific data on the levels of mercury found in fish from the Northern Dvina, particularly those in its estuary zone affected by the pulp and paper industry. The content and distribution of mercury were characterised using the most common fish species as an example. The difference was shown between mercury accumulation in different conditions and areas, with an analysis of relevant factors carried out.

Histopathology of Selected Economically Important Fish Species from the Escravos Estuary, Nigeria: A Baseline Study for Environmental Monitoring

Histopathology of Selected Economically Important Fish Species from the Escravos Estuary, Nigeria: A Baseline Study for Environmental Monitoring

Impact of Polyvinyl Chloride (PVC) powder ingestion on growth rate and length of Oreochromis niloticus - A Preliminary Study

Aquatic ecosystems face increasing contamination from plastic pollutants, with Polyvinyl Chloride (PVC) being one of the most prevalent. This study investigates the impact of ingested PVC powder particles on the body weight and length of O. niloticus (Nile tilapia), a commercially important fish species and a common inhabitant of freshwater systems worldwide. Groups of Nile tilapia specimens were subjected to different amounts of PVC powder particles, specifically 500 ppm and 1000 ppm. Specimens and water parameters were meticulously observed for 40 days. The control groups were provided with a diet that did not contain any PVC. After exposure, body weight and length were measured every two weeks and compared between the experimental and control groups. Preliminary results suggest a significant correlation between PVC ingestion and alterations in the growth parameters of Nile tilapia. Fish exposed to higher concentrations of PVC exhibited reduced body weight and length compared to the control groups. These findings indicate a potential negative impact of PVC pollution on the growth and development of aquatic organisms, highlighting the urgent need for effective strategies to mitigate plastic pollution in freshwater ecosystems.

Microbiomes of Tilapia Culture Systems: Composition, Affecting Factors, and Future Perspectives

With the increasing demand for global food resources, improving aquaculture production has been the focus for years. Tilapia has become one of the most commonly farmed and economically important fish species globally. Research efforts have recognized the significant roles that microbial communities play in improving the health and aquaculture performance of tilapia. However, interactions between tilapia and its associated microbial communities remain poorly understood. In this review, the current understanding of tilapia microbiomes is summarized. With fish being in intimate relationship with its environment, studies characterizing the microbial communities present in the rearing environment and how they affect tilapia microbiomes and health are also examined. Having an in‐depth understanding of the different microbiomes and their roles and interactions in the tilapia culture system is a crucial step toward managing and modulating these microbial communities to improve tilapia health. This review also sheds light on the different factors that influence tilapia microbiomes such as developmental stages, organ tissues, and types of culture systems. The effects of on‐farm practices such as diet; feeding regimes; use of probiotics, prebiotics, and synbiotics; vaccination; application of antibiotics; disinfection; and pond fertilization on tilapia microbiome are also discussed. Through this review, future research needs are identified that can provide a deeper understanding of the relationships among tilapia microbiomes, health, and productivity. These knowledge in turn can be harnessed into practical applications and potential microbiome‐based management protocols to improve future best management practices for tilapia aquaculture.

Genome-wide SNP analysis provides insights into the XX/XY sex-determination system in silver barb (Barbonymus gonionotus).

Silver barb (Barbonymus gonionotus) is among the most economically important freshwater fish species in Thailand. It ranks fourth in economic value and third in production weight for fisheries and culture in Thailand. An XX/XY sex-determination system based on gynogenesis was previously reported for this fish. In this study, the molecular basis underlying the sex-determination system was further investigated. Genome-wide single-nucleotide polymorphism data were generated for 32 captive-bred silver barb individuals, previously scored by phenotypic sex, to identify sex-linked regions associated with sex determination. Sixty-three male-linked loci, indicating putative XY chromosomes, were identified. Male-specific loci were not observed, which indicates that the putative Y chromosome is young and the sex determination region is cryptic. A homology search revealed that most male-linked loci were homologous to the Mariner/Tc1 and Gypsy transposable elements and are probably the remnants of an initial accumulation of repeats on the Y chromosome from the early stages of sex chromosome differentiation. This research provides convincing insights into the mechanism of sex determination and reveals the potential sex determination regions in silver barb. The study provides the basic data necessary for increasing the commercial value of silver barbs through genetic improvements.

Molecular and biological studies of nonindigenous and extremely rare fish species from the western Baltic reported from the Pomeranian Bay (southwest Baltic Proper)

W ięcaszek B., P anicz R., E ljasik P., Tański A., B ushra A. 2023. Molecular and biological studies of nonindigenous and extremely rare fish species from the western Baltic reported from the Pomeranian Bay (southwest Baltic Proper). Folia Biologica (Kraków) 71: 181-194. Water inflows from the North Sea to the Baltic Sea are recognized as a significant factor influencing the diversity of fish species in the region. In this report, we present findings on three newly discovered fish species (Solea solea, Merluccius merluccius, and Limanda limanda) and the presence of species that were previously seldom observed in the Pomeranian Bay and the associated oligohaline waters of Szczecin Lagoon. These fishes were incidentally captured during monitoring surveys of commercially important fish species. Species identification relied on partial sequences of cytochrome c oxidase subunit I (COI), cytochrome b (cytb), and rhodopsin (rho) genes, as well as morphometric diagnostic characteristics. Upon comparing the obtained sequences with GenBank records, it was revealed that the sequences for Merluccius merluccius (rho, GenBank acc. no. OM737733) and Chelidonichthys lucerna (cytb, GenBank acc. no. OM737734) constitute new DNA barcodes. The majority of sequences obtained in our study matched those available in GenBank for fishes inhabiting the North Sea, suggesting spatial and temporal linkages between the two seas. The remaining sequences exhibited similarity to data from the Cantabrian Sea, the coasts of France, and the Norwegian Sea. The study results, in conjunction with information on the inflows of saline waters and data from previous studies on reported fish occurrences, indicate that the bycatch species could serve as potential bioindicators of environmental changes in the study area.

Influence of the host sex, size, and season on Ergasilus lizae infestation of Thicklip Grey Mullet (Chelon labrosus, L., 1758) in Beymelek Lagoon Lake (Antalya, Türkiye)

The aim of the study was investigation of the changes in infestation levels of Ergasilus lizae on economically important fish species, thicklip grey mullet (Chelon labrossus) from Beymelek Lagoon Lake located on the western Mediterranean coast (Antalya, Türkiye). In this context, the infestation levels of E. lizae with respect to fish sexes, fish sizes and season were evaluated statistically. The research was conducted seasonally between May 2008 to April 2009, and the gills which belong to 103 fish samples were examined. The overall infection prevalence and mean intensity values were 60.2% and 15.95, respectively. The prevalence and mean intensity of E. lizae for thicklip grey mullet male and sexually unidentified fish samples were higher than that for females. Prevalence and mean intensity were determined the highest in size class I with 69.6% and 26.3, and almost the same values in size groups II and III. E. lizae on host fish were observed in every season. The highest prevalence and mean intensity of E. lizae was recorded in spring with 100%, 24.88. The lowest prevalence of E. lizae was recorded in summer at 12% and the lowest mean intensity of E. lizae was in the summer and the winter with 9, 8.67 respectively. The infestation level of E. lizae was statistically significant with host sex and season, but there was no effect on the fish size groups.

Analysis of Chromatin Accessibility and DNA Methylation to Reveal the Functions of Epigenetic Modifications in Cyprinus carpio Gonads.

Epigenetic modifications are critical in precisely regulating gene expression. The common carp (Cyprinus carpio) is an economically important fish species, and females exhibit faster growth rates than males. However, the studies related to epigenetic modifications in the common carp gonads are limited. In this study, we conducted the Assay for Transposase Accessible Chromatin sequencing (ATAC-seq) and Bisulfite sequencing (BS-seq) to explore the roles of epigenetic modifications in the common carp gonads. We identified 84,207 more accessible regions and 77,922 less accessible regions in ovaries compared to testes, and some sex-biased genes showed differential chromatin accessibility in their promoter regions, such as sox9a and zp3. Motif enrichment analysis showed that transcription factors (TFs) associated with embryonic development and cell proliferation were heavily enriched in ovaries, and the TFs Foxl2 and SF1 were only identified in ovaries. We also analyzed the possible regulations between chromatin accessibility and gene expression. By BS-seq, we identified 2087 promoter differentially methylated genes (promoter-DMGs) and 5264 gene body differentially methylated genes (genebody-DMGs) in CG contexts. These genebody-DMGs were significantly enriched in the Wnt signaling pathway, TGF-beta signaling pathway, and GnRH signaling pathway, indicating that methylation in gene body regions could play an essential role in sex maintenance, just like methylation in promoter regions. Combined with transcriptomes, we revealed that the expression of dmrtb1-like, spag6, and fels was negatively correlated with their methylation levels in promoter regions. Our study on the epigenetic modifications of gonads contributes to elucidating the molecular mechanism of sex differentiation and sex maintenance in the common carp.

Survey on fish diversity, resource potential and current production level ofmajor rivers in the Benishangul Gumuz Region; Ethiopia

With an estimated total population of 667,049 people, the region is situated at the lower fresh water reaches of the Abay basin. The rivers mainly grouped as Flood Rivers, where there are extremes of annual fluctuation in water level from severe flood to sometimes complete desiccation in dry season. There exists also considerable difference in numbers of species inhabiting various river systems attributed to the size of the river as represented by its basin area or correlated with the length of main channel or stream order. Five major rivers of the basin were chosen purposely. Sampling was made during 2011 and gillnets of different mesh sizes were used. For the estimation of the potential fish yield of each river, the simplest model relating catch and river length was used. Compared to the other rivers, the diversity of fish in Dabus River was lower. Totally 29 commercially important fish species,grouped in to 11 families, has been known to present. The dominant family in these river systems is Cyprinidae with a diversity of 9 species. Current fish production in the region is estimated only as 183 tons/yr. The estimated total fish production potentials of sampled rivers is found to be 2,400 tons/yr indicating that there is the possibility to increase the current level of production more than 13 times. Inaddition, the exploitation is limited to subsistence level. The most potential river in the region is Abay with an estimated potential of 1680 tons/year and Anger contributes the least potential.

Habitat modulates population-level responses of freshwater salmon growth to a century of change in climate and competition.

The impacts of climate change are widespread and threaten natural systems globally. Yet, within regions, heterogeneous physical landscapes can differentially filter climate, leading to local response diversity. For example, it is possible that while freshwater lakes are sensitive to climate change, they may exhibit a diversity of thermal responses owing to their unique morphology, which in turn can differentially affect the growth and survival of vulnerable biota such as fishes. In particular, salmonids are cold-water fishes with complex life histories shaped by diverse freshwater habitats that are sensitive to warming temperatures. Here we examine the influence of habitat on the growth of sockeye salmon (Oncorhynchus nerka) in nursery lakes of Canada's Skeena River watershed over a century of change in regional temperature and intraspecific competition. We found that freshwater growth has generally increased over the last century. While growth tended to be higher in years with relatively higher summer air temperatures (a proxy for lake temperature), long-term increases in growth appear largely influenced by reduced competition. However, habitat played an important role in modulating the effect of high temperature. Specifically, growth was positively associated with rising temperatures in relatively deep (>50 m) nursery lakes, whereas warmer temperatures were not associated with a change in growth for fish among shallow lakes. The influence of temperature on growth also was modulated by glacier extent whereby the growth of fish from lakes situated in watersheds with little (i.e., <5%) glacier cover increased with rising temperatures, but decreased with rising temperatures for fish in lakes within more glaciated watersheds. Maintaining the integrity of an array of freshwater habitats-and the processes that generate and maintain them-will help foster a diverse climate-response portfolio for important fish species, which in turn can ensure that salmon watersheds are resilient to future environmental change.

Identification of genes related to growth from transcriptome profiles of the muscle and liver of Chinese longsnout catfish (Leiocassis longirostris)

The Chinese longsnout catfish (Leiocassis longirostris) is a commercially important freshwater fish species in China. To understand the molecular mechanisms underlying its growth, we performed a comparative transcriptomic analysis of muscle and liver tissues of fast- and slow-growing L. longirostris. A total of 580 and 511 differentially expressed genes (DEGs) were obtained in the muscle and liver tissues, respectively. We selected 10 DEGs each from muscle and liver tissues by qRT-PCR to verify the reliability of RNA-seq, and it was found that the expression patterns of these genes were consistent with RNA-seq analysis results. According to the differential expression and functional enrichment analysis of genes, we found differences in the expression of several growth-related genes between fast- and slow-growing individuals. These genes may contribute to the differences in the growth of L. longirostris by influencing muscle growth and the metabolism of substances and energy. In particular, the pk and fabp genes were highly expressed in fast-growing individuals, while the cart, leptin, pepck, murf1, trim32, and pparα genes exhibited higher levels in slow-growing individuals. It was speculated that genes related to feeding behavior might be the key genes in regulating the growth of L. longirostris, while glycolytic/gluconeogenic metabolic pathway, lipid metabolism, and ubiquitin-proteasome pathway might be the main pathways involved in regulating body weight of L. longirostris. This study could enrich the available gene resources and provide a valuable basis for further studies on the regulatory mechanisms of growth in L. longirostris.

The combined effects of acidification and acute warming on the embryos of Pacific herring (Clupea pallasii)

Anthropogenic climate change is projected to affect marine ecosystems by challenging the environmental tolerance of individuals. Marine fishes may be particularly vulnerable to emergent climate stressors during early life stages. Here we focus on embryos of Pacific herring (Clupea pallasii), an important forage fish species widely distributed across the North Pacific. Embryos were reared under a range of temperatures (10-16°C) crossed with two pCO2 levels (600 and 2000 μatm) to investigate effects on metabolism and survival. We further tested how elevated pCO2 affects critical thermal tolerance (CTmax) by challenging embryos to short-term temperature fluctuations. Experiments were repeated on embryos collected from winter and spring spawning populations to determine if spawning phenology corresponds with different limits of environmental tolerance in offspring. We found that embryos could withstand acute exposure to 20°C regardless of spawning population or incubation treatment, but that survival was greatly reduced after 2-3 hours at 25°C. We found that pCO2 had limited effects on CTmax. The survival of embryos reared under chronically warm conditions (12°, 14°, or 16°C) was significantly lower relative to 10°C treatments in both populations. Oxygen consumption rates (MO2) were also higher at elevated temperatures and pCO2 levels. However, heart contraction measurements made 48 hours after CTmax exposure revealed a greater increase in heart rate in embryos reared at 10°C compared to 16°C, suggesting acclimation at higher incubation temperatures. Our results indicate that Pacific herring are generally tolerant of pCO2 but are vulnerable to acute temperature stress. Importantly, spring-spawning embryos did not clearly exhibit a higher tolerance to heat stress compared to winter offspring.

Preliminary microchemical analyses of North-western Persian Gulf hilsa shad otolith trace elements: Indications of complex migratory behavior and stock structure

Hilsa shad (Tenualosa ilisha) is an important anadromous fish species, supporting significant commercial and subsistence fisheries throughout south Asia. Otolith Sr:Ca and Ba:Ca profiles were used along with age data to examine the migratory history of hilsa shad from two major river systems in the northwestern Persian Gulf (Karun and Zohreh). In addition, elemental ratios (Sr:Ca, Ba:Ca, and Li:Ca) were analyzed using principal component analysis to investigate regional population structure. Variation in movement patterns was observed, though all fish analyzed had spent some time in freshwater, and most otolith signatures suggested a double downstream marine/upstream freshwater migration. There were however differences among rivers: the majority of fish from Zohreh River showed a single downstream/upstream migration through their life cycle, while Karun signatures were more complex, with multiple migrations and potential estuarine or freshwater residence. When comparing stock structure during the marine phase, the otolith signatures of Zohreh River fish showed greater separation while others tended to overlap, indicating that Zohreh fish were likely to have reared in a different location than the others. Although comprising a relatively small sample size, our results provide some preliminary insights into the life-history and stock structure of Persian Gulf hilsa shad, informing the management needs of this important fishery, and suggesting further more detailed investigations of migration and stock structure are warranted.

Fauna of metazoan parasites of Pterygoplichthys pardalis (Castelnau, 1855) sold at fairs in the city of Manaus, state of Amazonas, Brazil

Pterygoplichthys pardalis is an endemic as well as economically important fish species in the Amazon basin. Thirty P. pardalis specimens were purchased at assorted fairs in the city of Manaus. Fish were necropsied, and then, had their organs investigated for parasites. The identified parasites were observed under Light bright field microscopy and that of Scanning Electron Microscopy (SEM). Through the analyses it was observed 219 metazoan parasite specimens, belonging to four taxonomic groups: Monogenoidea, Digenea, Acanthocephala, and Copepoda. Six metazoan parasitic species were identified: Monogenoidea Unilatus unilatus Mizelle and Kritsky, 1967 and Copepoda Therodamas elongatus (Thatcher, 1986) from the gills, Digenea Austrodiplostomum compactum (Lutz, 1928), Megacoelium spinicavum Szidat, 1954 and Diplostomum sp. from the eyes, stomach, and gonads, respectively, and Acanthocephala Gorytocephalus elongorchis Thatcher, 1979 from the intestine. Gorytocephalus elongorchis was the one presenting the highest prevalence value, followed by digeneans M. spinicavum, Diplostomum sp., and A. compactum. The present study has come to provide the very first SEM M. spinicavum, G. elongorchis, and T. elongatus images, thus improving on the up to now available data addressing P. pardalis parasitic fauna, which has been found to be infecting, the fish species presently being marketed in Manaus. Moreover, the current survey has demonstrated the identified parasite species pose no public health concern at all.

Evaluation Performance of Three Standardization Models to Estimate Catch-per-Unit-Effort: A Case Study on Pacific Sardine (Sardinops sagax) in the Northwest Pacific Ocean

Catch-per-unit-effort (CPUE) standardization in fisheries is a critical foundation for conducting stock assessment and fishery conservation. The Pacific sardine (Sardinops sagax) is one of the economically important fish species in the Northwest Pacific Ocean (NPO). Hence, the importance of choosing an appropriate CPUE standardization model cannot be overstated when it comes to achieving a precise relative abundance index for the efficient management of Pacific sardine fishery. This study’s main aim was to assess and compare the efficacy of three models, specifically the General Linear Model (GLM), the Generalized Linear Mixed Model (GLMM), and the spatio-temporal GLMM (VAST), in the CPUE standardization for Pacific sardine fishery in the NPO, with the ultimate goal of identifying the most appropriate model. An influence analysis was applied to analyze the impact of individual variables on the disparity among standardized and nominal CPUE, and the main explanatory variables influencing standardized CPUE were identified. A coefficient–distribution–influence (CDI) plot was generated to analyze the impact of the different models on the annual standardized CPUE. Additionally, a simulation testing framework was developed to evaluate the estimated accuracy of the three models. The results indicated that the standardized CPUE and the nominal CPUE exhibited similar trends between 2014 and 2021 for the three models. Compared to the GLM and the GLMM, the VAST demonstrates larger conditional R2 and smaller conditional AIC, indicating a better performance in standardizing the CPUE for Pacific sardines due to its consideration of spatial and temporal variations. The interaction terms within the three models exert significant influences on the annual standardized CPUE, necessitating their inclusion in the model construction. CDI plots indicate that the spatio-temporal influence of the VAST model exhibits a smaller variation trend, suggesting that the VAST is more robust when standardizing the CPUE for Pacific sardines. Simulation testing additionally demonstrated that the VAST model displays smaller model root mean squared error (RMSE) and bias, establishing it as the superior performer for standardizing CPUE. Our results provide a theoretical basis for the scientific management of Pacific sardines in the NPO and can be extended to CPUE standardization for other small pelagic fish species worldwide.

TBK1 upregulates the interferon response against virus by the TBK1-IRF3/7 axis in yellow catfish (Pelteobagrus fulvidraco)

Yellow catfish (Pelteobagrus fulvidraco) is an important economic species of freshwater fish, widely distributed in China. Recently, viral diseases of yellow catfish have been identified in Chian (Hubei province), arising more attention to the viral immunity in P. fulvidraco. Tumor necrosis factor (TNF) receptor-associated factor NF-κB activator (TANK)-binding kinase 1 (TBK1) plays an essential role in IFN production and innate antiviral immunity. In the present study, we characterized the P. fulvidraco TBK1 (PfTBK1) and reported its function in interferon response. The full-length open reading frame (ORF) is 2184 bp encoding a protein with 727 amino acids, which is composed of four conserved domains, including KD, ULD, CCD1, and CCD2, similar to TBK1 in other species. Pftbk1 was widely expressed in all detected tissues by qPCR and was not inducible by the spring viremia of carp virus (SVCV), a single-strand RNA virus. In addition, the cellular distribution indicated that PfTBK1 was only located in the cytoplasm. Moreover, PfTBK1 induced strong IFN promoter activities through the Jak-stat pathway, and PfTBK1 interacted with and significantly phosphorylated IFN regulatory factor 3/7 (IRF3/7) in P. fulvidraco, promoting the nuclear translocation of pfIRF3 and PfIRF7, and PfTBK1 upregulated IFN response by PfTBK1-PfIRF3/7 axis. Above all, PfTBK1 triggered IFN response and strongly inhibited the replication of SVCV in EPC cells through induction of IFN downstream IFN-stimulated genes (ISGs). Summarily, this work reveals that PfTBK1 plays a positive regulatory role in IFN induction through the TBK1-IRF3/7 axis, laying a foundation for further exploring the molecular mechanism of the antiviral process in P. fulvidraco.