Konosirus Research Articles

Tissue-specific distribution and fatty acid content of PFAS in the northern Bohai Sea fish: risk-benefit assessment of legacy PFAS and emerging alternatives

This study aimed to examine the distribution of poly- and perfluoroalkyl substances (PFAS) in 15 marine fish species from the northern Bohai Sea, investigate their sources of contamination, and evaluate the benefits-risks associated with the concurrent consumption of fish fatty acids and PFAS. The ∑PFAS concentrations in fish ranged from 9.38 to 262.92ng·g-1 (dry weight). The highest PFAS levels were found in the viscera and gills, while the lowest levels were found in the muscles. Industrial effluents and sewage treatment plant discharges were the primary sources of PFAS contamination. The individual PFAS concentrations in fish were insignificantly correlated with their trophic levels (p > 0.05). However, the concentrations of hexafluoropropylene oxide dimer acid (HFPO-DA) or long-chain PFAS (C > 8) significantly increased with fish size (e.g., total length, weight) and lipid content (p < 0.001). The benefit-risk analysis suggests that HPFO-DA poses a higher health risk than perfluorooctanoic acid (PFOA) in fish (p<0.05). Long-term consumption of contaminated fish may significantly increase human serum PFOA concentration and kidney cancer risk (p<0.05). Daily consumption of 5g (wet weight) muscle from Ditrema temmincki and Konosirus punctatus is recommended to meet the requirements for fatty acid supplementation without posing health risks.

Effects of Climate Change on the Distribution of Scomber japonicus and Konosirus punctatus in China’s Coastal and Adjacent Waters

Climate change has increasingly impacted the marine environment, with various marine environmental factors interacting to influence fish distribution. Assessing the impact of climate change on the future distribution of fish depends on understanding how biological responses interact with environmental conditions. Enhancing our understanding of the potential impacts of climate change is crucial for the sustainable development of marine fisheries. In this study, we analyzed the habitat suitability of Scomber japonicus and Konosirus punctatus in the coastal waters of China (17°–41° N, 107°–130° E) using marine environmental data, including, as follows: sea surface temperature (SST); sea surface salinity (SSS); pH; and biological occurrence data from 2000 to 2010. A maximum entropy (MaxEnt) model was employed to predict the future distribution of these two species based on the shared socioeconomic pathway (SSP) scenarios for 2040–2050 and 2090–2100. The results indicate that climate change will significantly affect the future habitat distribution of S. japonicus and K. punctatus, leading to a decrease in suitable habitat areas offshore China and a gradual shift northeastward in the center of these habitats. These findings are essential for understanding the impacts of climate change on the distribution of S. japonicus and K. punctatus, with significant implications for fisheries resource assessment and management.

Characteristics and radiological hazard assessment of 210Po activity level in Dotted gizzard shad (Konosirus punctatus) from Quang Ninh province, Northern Vietnam

The natural radionuclide 210Po accumulates readily in marine organisms and is a significant contributor to the radiological dose from consuming seafood. This study analyzed the 210Po activity in thirty specimens of Dotted gizzard shad, a common and commercially important species of Clupeiform fish distributed in Quang Ninh province, Vietnam. The measurements were taken using an alpha spectrometer to measure the radionuclide from various tissues collected from each fish specimen. The highest activities of 210Po were found in the liver and intestine, while the lowest activity was observed in muscle tissue. The trend of 210Po activity in the different tissues was muscle < skin < stomach < gill < bone < intestine < liver, with mean values of 15.1 ± 1.7, 39.6 ± 9.6, 51.2 ± 5.5, 58.2 ± 7.2, 62.2 ± 13.5, 241 ± 18.7, and 346 ± 30.5 Bq.kg−1, respectively. There was an insignificant correlation between 210Po activity in the muscle and the mass and size of the fish. The calculated annual effective dose for adults from consuming only the Dotted gizzard shad containing 210Po exceeded the recommendation value (1 mSv.y−1) for all tissues except muscle. The concern for exceeding ingestion doses applies primarily to consumers who choose to eat the organs, including the gastrointestinal tract, of Dotted gizzard shad, assuming an annual consumption of 27 kg.y−1 for each organ. Therefore, this study emphasizes that people should be advised not to consume the digestive organs of Dotted gizzard shad to avoid radiological risk.

Salt-Reduced Fish Sauce Produced under Pressurized Carbon Dioxide Treatment Using Sardinops melanostictus, Trachurus japonicus, Konosirus punctatus, Odontamblyopus lacepedii, Their Collective Mixture, and Unused Fish Mixture.

Fish sauce is produced at high salt concentrations (>20%) to inhibit the growth of harmful microorganisms. The salt-reduced fish sauce (10% salt) was prepared under pressurized CO2 (pCO2) conditions at 30 °C and 5 MPa for 3 months (FSCO2), from Sardinops melanostictus, Odontamblyopus lacepedii, Trachurus japonicus, Konosirus punctatus, and their collective mixture, as well as unused fish mixture obtained from the Ariake Sea in Japan. FSCO2 exhibited significantly better microbial quality and free amino acid content, lighter color, standardized odor (dashi-like odor), and umami richness qualities compared to fish sauces prepared using the conventional method (FScon) (20% salt), as previously demonstrated, after a fermentation period of 2 months. Bacterial flora analysis implied that the standardization of odor and umami richness may not be the result of specific microbial metabolism. Even when using previously unused fish, it was possible to produce FSCO2 equivalent to that produced by conventional sardines and other fish. These results indicate that the quality of fish sauce can be improved. The flavor of FSCO2 became similar regardless of the type of fish and fermentation period using pCO2 during fermentation, leading to the effective utilization of unutilized fish as a resource for high-quality salt-reduced fish sauce.

Identification of Konosirus punctatus (Temminic and Schlegel, 1846) stocks in Korean waters via otolith shape analysis and comparison of growth parameters

Accurate identification of fish stocks is essential for the successful management of fishery resources. In this study, the populations of dotted gizzard shad, Konosirus punctatus, which is listed on the International Union for Conservation of Nature red list of the threatened species, were identified by combining two phenotypic methods: otolith shape analysis and comparison of growth parameters. Otolith shape analysis revealed two types of otoliths, pointing to the presence of two gizzard shad stocks in two areas along the Korean coast: the East Sea and the Yellow Sea + western Korean Strait. It is also supported by the result that the two stocks are significantly different in the shape indices (SI), and asymptotic fork length (FL∞). These results may be due to the influence of several environmental factors, such as temperature, salinity, and food availability. Overall, our findings suggest that there are two phenotypic stocks of K. punctatus in the Korean coastal waters and they should be managed differently.

Optimization of Extraction and Refining Parameters of Oil from Dotted Gizzard Shad (Konosirus punctatus).

To address the challenges associated with resource inefficiency, low extraction rates, environmental concerns, and high energy consumption in traditional fish oil production from dotted gizzard shad (Konosirus punctatus), a novel approach is needed. This study aimed to develop and evaluate two innovative methods for fish oil extraction and refinement, focusing on their effects on fish oil quality, fatty acid profile, and volatile compound composition throughout the respective processes. The findings of the study revealed that the ethanol-assisted enzymatic extraction method surpassed the conventional enzymatic approach in extraction efficiency, achieving an optimal extraction rate of 74.94% ± 0.45% under optimized process conditions. Moreover, the ethanol-NaOH one-step degumming and deacidification method proved effective in simultaneously removing phospholipids and free fatty acids. Under optimal conditions, a notable reduction in phospholipid content in dotted gizzard shad oil, from 6.80 ± 0.01 mg/g to 1.18 ± 0.01 mg/g, and a substantial decrease in acid value, from 3.31 mg/g to 0.31 mg/g, were observed. In summary, the study analyzed the physicochemical properties, fatty acid composition, and volatile components of fish oil before and after refinement. The refining process was found to preserve the fatty acid composition while efficiently eliminating hydroperoxides and reducing unpleasant odors in the crude oil.

Development of Twenty Novel Polymorphic Microsatellite Markers and Their Application in Population Genetic Studies of Konosirus punctatus

Development of Twenty Novel Polymorphic Microsatellite Markers and Their Application in Population Genetic Studies of Konosirus punctatus

A Machine Learning Technique for Deriving the Optimal Mesh Size of a Gizzard Shad (Konosirus punctatus) Gillnet

Gizzard shads are facing a continual decline in population, necessitating the implementation of selective gear design for effective resource management. This study aims to prevent the bycatch of young gizzard shads, a non-target fish species, and to derive mesh sizes appropriate for fishery management. Experimental fishing (n = 11) was conducted by manufacturing gillnet fishing gear with different mesh sizes (50.5, 55.1, 60.6, and 67.3 mm) in the coastal waters of the southern Gyeongsang Province. Two methods were employed to estimate the appropriate mesh size of the shad gillnet as follows: firstly, by analyzing the selectivity curve based on body length data; secondly, by developing a complex machine learning model considering biological and economic factors. Model 1 was constructed using mesh variables to classify the score groups. As a result of this study, the total length with a 0.5 gillnet selection ratio. which was estimated to be 179.3, 195.6, 215.1, and 238.9 mm for the 50.5, 55.1, 60.6, and 67.3 mm mesh sizes, respectively. In Model 1, a mesh size of 57.85 mm or less was determined as the most appropriate mesh size. Therefore, considering both biological and economic aspects, shad gillnets should have a mesh size in the 50.5 to 55.1 mm range.

New perspectives on the genetic structure of dotted gizzard shad (Konosirus punctatus) based on RAD-seq

To maintain, develop and rationally utilize marine organisms, understanding their genetic structure and habitat adaptation pattern is necessary. Konosirus punctatus, which is a commercial fish species inhabiting the Indo-west Pacific Ocean, has shown an obvious annual global capture and aquaculture production decline due to climate changes and human activities. In the present study, restriction-site associated DNA sequencing (RAD-seq) was used to describe its genome-wide single nucleotide polymorphisms panel (SNPs). Among 146 individuals collected at nine locations scattered in China, Korea and Japan, a set of 632,090 SNPs were identified. Population genetic analysis showed that K. punctatus individuals were divided into two significant genetic clusters. Meanwhile, potential genetic differentiation between northern and southern population of K. punctatus was found. Treemix results indicated that gene flow existed among sampling locations of K. punctatus, especially from southern Japan to others. Moreover, candidate genes associated with habitat adaptations of K. punctatus were identified, which are involved in diverse physiological processes of K. punctatus including growth and development (e.g., KIDINS220, PAN3), substance metabolism (e.g., PGM5) and immune response (e.g., VAV3, CCT7, HSPA12B). Our findings may aid in understanding the possible mechanisms for the population genetic structure and local adaptation of K. punctatus, which is beneficial to establish the management and conservation units of K. punctatus, guiding the rational use of resources, with reference significance for a profound understanding of the adaptative mechanisms of other marine organisms to the environment.

Seasonal variations in the diversity and benthic community structure of subtidal artificial oyster reefs adjacent to the Luanhe River Estuary, Bohai Sea

Artificial oyster reefs provide important spawning and nursery grounds for a variety of fishes and large mobile crustaceans. Between July 2016 and May 2017, seasonal surveys of species composition and community structure were performed in the artificial oyster reef area and control area adjacent to the Luanhe River Estuary in China. During the survey year, 56 species belonging to 50 genera, 45 families, and 19 orders were recorded. The dominant economically important fish and mobile crustaceans were Hexagrammos otakii, Pholis fangi, Sebastes schlegelii, Charybdis japonica, and Oratosquilla oratoria. Resident fishes belonged to the Cynoglossidae, Paralichthyidae, Pleuronectidae, and Gobiidae families. Seasonally important fish species included Lateolabrax japonicus, Konosirus punctatus, Thryssa kammalensis, Hexagrammos agrammus, and Acanthopagrus schlegelii. The ranges of H' values among stations were 1.18–2.16, 0.65–1.75, 1.18–2.06, and 0.62–1.92 in spring, summer, autumn, and winter, respectively. The benthic organisms present in the community of artificial oyster reef areas can be classified into groups according to month and season. The abundance biomass curves showed that the oyster reef area in spring, autumn, and winter experienced low disturbance, whereas the community structure in summer was subject to large variations from external disturbance. We also found that as the age of the oyster reefs increased, the percentage of oysters in the low shell height group (< 40 mm) decreased. The oyster density was 324 ind/m2 for the reef created in 2016, 724 ind/m2 for the reef created in 2015, and 364 ind/m2 for the reef created in 2013. These findings can be used to develop suitable management strategies for the sustainable maintenance of artificial oyster reef ecosystems.

Bactericidal effect of water-washing methods on Vibrio vulnificus contaminated in a raw fish Konosirus punctatus: water type, temperature, and pH.

This study aimed to evaluate a method for effectively reducing Vibrio vulnificus contamination in fish based on the type of washing water and method. Texture profiles and sensory evaluations were performed to determine the effect of the developed method on the quality and preference of the samples. The selected fish sample was Konosirus punctatus, which is mainly consumed in Asian countries. Various factors that could affect the survival rate of V. vulnificus were reviewed, including water type, temperature, exposure time, organic acids, pH, and washing methods. As a result, immersion and washing with filtered water with pH adjusted to 4.0 using acetic acid showed a high bactericidal effect of 2.5 log MPN/100g. Furthermore, this method showed no statistically significant effect on the texture and sensory characteristics of fish. The results of the present study suggest a simple and effective method for preventing V. vulnificus infection in raw fish.

Interannual Variation of Ichthyoplankton Community Structure in the Yellow River Estuary, China

To understand the community structure dynamics of fish eggs and larvae in the Yellow River estuary, four trawl surveys were annually conducted between 2011 and 2014, including at 13 stations in 2011 and 18 stations between 2012 and 2014. A total of 2540 eggs and 143 larvae were collected during the four surveys, comprising 25 species, 8 orders, 16 families, and 20 genera. During the survey period, species numbers of eggs first decreased and then increased, while abundances first increased and then decreased. Larval species numbers exhibited the same trends as for eggs, while larval abundances fluctuated across the four years of the study. The primary species represented by the eggs were Konosirus punctatus, Sillago sihama, and Cynoglossus joyeri, while the larval species primarily comprised Amblychaeturichthys hexanema, Chaeturichthys stigmatias, and Engraulis japonicus. Cluster analysis of species compositions for eggs and larvae revealed the presence of four groups, wherein groups 1–3 comprised communities from 12, 3, and 2 stations, respectively, that were primarily distributed in the eastern part of the estuary. In contrast, group four only comprised communities from one station at the western part of the estuary near Bohai Bay. All biodiversity indices were lowest in 2012 and biodiversity of fish egg and larval communities were most correlated with the water depth among the parameters that were measured. Overall, interannual variation in the distribution and diversity of fish egg and larval communities in the Yellow River estuary reflected the responses of fish to environmental variability.

Dietary Protein Requirement of Juvenile Dotted Gizzard Shad Konosirus punctatus Based on the Variation of Fish Meal.

An 8-week feeding trial was conducted to investigate the effects of dietary protein levels on growth performance, feed utilization, and energy retention of juvenile dotted gizzard shad Konosirus punctatus based on the variation of fish meal. Fish meal was used as the sole protein source; five semi-purified diets were formulated with varying crude protein (CP) levels of 22.52%, 28.69%, 34.85%, 38.84%, 45.78% (CP1-CP5 diets). A total of 300 uniform juveniles with initial body weight 3.61 ± 0.20 g fish-1 were randomly divided into five groups with three replicates in each group. The results showed that different CP levels did not significantly affect the survival of juvenile K. punctatus (p > 0.05). The values of weight gain (WG) and specific growth ratio (SGR) showed a general enhancing trend and then weakened with increasing dietary CP levels (p > 0.05). Feed utilization also improved with increasing dietary CP levels (p > 0.05), and the optimal feed conversion ratio (FCR) value was found in fish fed the diet with CP3 (p > 0.05). The rise of dietary CP from 22.52% to 45.78% enhanced the daily feed intake (DFI) and protein efficiency ratio (PER) values of K. punctatus (p < 0.05). With the increase of dietary CP levels, daily nitrogen intake (DNI), energy retention (ER), and lipid retention (LR) elevated, while retention (NR), daily energy intake (DEI), and daily lipid intake (DLI) reduced (p < 0.05). No statistical differences in the content of water, crude protein, and crude lipid were observed among different treatments (p > 0.05). The activity of lipase in CP3 and CP4 diets was significantly higher than that of the CP1 diet (p < 0.05). Fish fed CP2 and CP3 diets had significantly higher amylase activity than that of the CP5 diet (p < 0.05). The levels of alanine aminotransferase (GPT) first enhanced and then decreased as dietary CP levels raised. The second-order polynomial regression model analysis of the WG and FCR indicated that the optimal dietary protein level for K. punctatus is about 31.75-33.82% based on the variation of fish meal.

Population structure and genetic diversity in wild dotted gizzard shad (Konosirus punctatus) revealed by microsatellite markers

Uncovering the fine-scale genetic structure has been long recognized as a key component in policymaking for the management of marine fisheries. Many species of Clupeiformes have suffered declines owing to overexploitation and habitat destruction. In this study, twenty polymorphic microsatellite markers were used to evaluate the genetic diversity and population structure of Konosirus punctatus, a pelagic fish of economic and ecological importance in the Northwestern Pacific Ocean. Although most of the variance occurred within individuals, significant differentiation (FST = 0.00384~0.19346) was shown in wild K. punctatus populations. Population structure analyses revealed five genetically divergent clades in K. punctatus in the Northwestern Pacific. Significant isolation by distance and one potentially outlier locus were revealed in K. punctatus, suggesting that interactions between historical climate shifts and environmental factors may contribute to the present-day genetic architecture. In summary, these results provided new perspectives on the population genetic structure of K. punctatus, facilitating the development of effective management strategies for this species.

Simple and rapid method for molecular identification of Konosirus punctatus and Clupanodon thrissa

Simple and rapid method for molecular identification of Konosirus punctatus and Clupanodon thrissa

A case of mycobacteriosis associated with Mycobacterium pseudoshottsii in aquarium-reared fish in Japan.

In 2019, several aquarium-reared fish died at a sea life park in Japan. Necropsy revealed micronodules on the spleen in the dotted gizzard shad (Konosirus punctatus). Seven of 16 fish exhibited microscopic multifocal granulomas associated with acid-fast bacilli in the spleen, kidney, liver, alimentary tract, mesentery, gills, and/or heart. Bacterial cultures yielded isolates from the dotted gizzard shad and a Japanese sardine (Sardinops melanostictus). Microbiological and molecular biological examinations revealed the isolates as Mycobacterium pseudoshottsii. To our knowledge, this is the first isolation of M. pseudoshottsii from aquarium-reared fish.

ADDITIONAL DATA ON SPECIES COMPOSITION OF FISH IN TIEN HAI WETLAND NATURE RESERVE, THAI BINH PROVINCE

Mangrove forests are important for many fish species, but this information is still poorly understood in Vietnam. Tien Hai Wetland Nature Reserve is located in the core areas of the Red River Delta Biosphere Reserve, where mangrove forests are presented. To provide fundamental data for a better understanding of the role of mangroves for fishes, three surveys in March, July, and August 2019 at 5 stations within Tien Hai Wetland Nature Reserve were conducted. A total of 817 individuals were collected and 65 species belonging to 54 genera, 28 families of 11 orders were identified. Of the 11 orders, Perciformes was the most diverse in a number of families, and Gobiiformes was dominant in the number of species. Of the 65 species, three were listed in Vietnam Red Data Book (2007), i.e., Bostrychus sinensis as CR level, Clupanodon thrissa as EN level, Konosirus punctatus as VU level, and an invasive alien species (Oreochromis mossambicus). The present study added 15 species to the study site and 10 fish to the lowland of the Red River in comparison with previous works. In the additional list, there were some typical species, which are associated with mangrove forests, such as Escualosa thoracata, Muraenichthuys gymnopterus, and 17 species of gobies. The ichthyofauna in Tien Hai Wetland Nature Reserve was different from Phu Long mangrove forests (in Hai Phong), and significantly different from Van Uc estuary (in Hai Phong) and Bung Binh Thien wetland (in An Giang). These findings will be valuable for fish conservation and fisheries resources development in the study area.

Activity Levels of 210Po, 210Pb and Other Radionuclides (134Cs, 137Cs, 90Sr, 110mAg, 238U, 226Ra and 40K) in Marine Organisms From Coastal Waters Adjacent to Fuqing and Ningde Nuclear Power Plants (China) and Radiation Dose Assessment

With the rapid development of nuclear power, the radiation impacts on edible marine organisms, and the potential radiation risks to humans have become of considerable concern to public health. In this study, the activities of 210Po and 210Pb as well as those of other radionuclides in fishes (Mugil cephalus, Konosirus punctatus, Largehead hairtail, and Larimichthys polyactis), crustaceans (Mantis shrimp, Parapenaeopsis hardwickii, and Portunus trituberculatus), bivalves (Crassostrea gigas, Sinonovacula conzcta), and macroalgae (Gracilaria, Porphyra) collected in the coastal area adjacent to the Fuqing and Ningde nuclear power plants (NPPs) were determined. The activity range of 210Po and 210Pb was 0.60–48.09 and 0.07–2.76 Bq/kg freshweight, respectively, with 210Po/210Pb activity ratios of 1.1–189.7. The ranking of 210Po activity levels in marine organisms was bivalve mollusks &amp;gt; crustaceans &amp;gt; fishes &amp;gt; macroalgae. The calculated bioconcentration factors of 210Po and 210Pb were 636–44,944 and 3–1,226 L/kg, respectively. These values provide a new supplement to the IAEA reference database. The radiation dose rates for these marine organisms ranged from 0.037 to 1.531 μSv/h, which was much lower than the ERICA ecosystem screening benchmark of 10 μGy/h. The calculated committed effective dose received by humans from ingestion of these marine organisms was 0.06–2.99 mSv. Overall, 210Po was the dominant radiation dose contributor in marine organisms and humans, whereas the dose contributions from the artificial nuclides 90Sr and 137Cs were negligible.

Spatio-temporal distribution of Konosirus punctatus spawning and nursing ground in the South Yellow Sea

Spatio-temporal distribution of Konosirus punctatus spawning and nursing ground in the South Yellow Sea

Fish environmental DNA in Tokyo Bay: A feasibility study on the availability of environmental DNA for fisheries

Environment DNA (eDNA) is a nonlethal sampling method that has potential for evaluating fisheries resources. To evaluate whether eDNA information is useful for fisheries, we collected and analysed eDNA samples from 14 sites in Tokyo Bay from April 2018 to March 2020. Using MiFish universal primers, fish mitochondrial 12S rRNAs were amplified from the eDNA by polymerase chain reaction (PCR) and then sequencing. A total of 535 eDNA samples yielded 44.5 million reads, with 197 of teleosts and 16 of elasmobranchs identified. Of those, 42 identified species were commercially important, with the most abundant being Engraulis japonicus (Japanese anchovy), followed by Konosirus punctatus (dotted gizzard shad) and Lateolabrax japonicusi (Japanese seabass). Mitochondrial cytochrome b copy numbers of K. punctatus and L. japonicus showed a seasonal trend, although catch per unit effort for L. japonicus was not correlated with copy number. Although eDNA is a powerful tool that can detect the presence of fish species from a water sample, caution should be used when interpreting fish biomass based on eDNA dynamics until the method has been better studied.