Bighead Carp Research Articles

Changes of Fatty Acid Compositions, Volatile Compounds, and Microbial Flora of Bighead Carp (Aristichthys nobilis) Heads during the Simulated Fresh Logistics Transportation

The changes of fatty acid compositions, volatile components, and microbial flora of bighead carp heads during fresh transportation were investigated. The brain, eye muscle, muscle near the incision (on the abdomen 5 cm away from the gills), and jaw muscle of bighead carp heads at ambient temperature (25°C) for 6 h and simulated fresh transportation (underwent ice storage and vibration) for 36 h and 72 h were evaluated. The content of monounsaturated fatty acids (38.98%) in four parts of bighead carp heads was the highest followed with saturated fatty acids (30.92%) band polyunsaturated fatty acids (24.50%), and their contents as well as the sensory quality were decreased significantly with the prolongation of fresh transportation time. There were significant differences in the composition and contents of volatile flavor compounds in the bighead carp heads during fresh transportation, including alcohols, aldehydes, esters, aromatic compounds, hydrocarbons, and other compounds, especially ketones and amines. In addition, the species richness of bighead carp heads decreased gradually with the extension of transportation time. The flora was mainly composed of Firmicutes and Proteus at the phylum level and Streptococcus and Lactococcus at the genus level. Conclusively, ketone and amine compounds in volatile substances as well as the dominant spoilage bacteria (Streptococcus) in the flora could be used as spoilage markers during the fresh transportation of bighead carp heads. Practical Application. Bighead carp head has gradually become a hot online product in China due to its rich nutrition and delicious taste. Fresh transportation is one of the most common methods for preserving fish to improve its nutrition, flavor, and taste. This paper is aimed at investigating the changes in quality, fatty acid content, volatile compounds, and microbial flora of bighead carp heads during fresh transportation. The results of this study provide a better understanding of the spoilage volatiles and bacteria for bighead carp heads during fresh transportation. It could provide a guiding and theoretical basis for the routine fresh-keeping transportation of bighead carp heads and offer a security assessment for their nutritional value.

Transcriptome analyses reveal differentially expressed genes associated with development of the palatal organ in bighead carp (Hypophthalmichthys nobilis)

The palatal organ is a filter-feeding related organ and occupies a considerable proportion of the head of bighead carp (Hypophthalmichthys nobilis), a large cyprinid fish intensive aquaculture in Asia. In this study, we performed RNA-seq of the palatal organ during growth periods of two (M2), six (M6) and 15 (M15) months of age after hatching. The numbers of differentially expressed genes (DEGs) were 1384, 481 and 1837 for M2 VS M6, M6 VS M15 and M2 VS M15 respectively. The following signaling pathways of energy metabolism and cytoskeleton function were enriched, including ECM-receptor interaction, Cardiac muscle contraction, Steroid biosynthesis and PPAR signaling pathway. Several members of collagen family (col1a1, col2a1, col6a2, col6a3, col9a2), Laminin gamma 1 (lamc1), integrin alpha 1 (itga1), Fatty acid binding protein 2 (fads2) and lipoprotein lipase (lpl), and Protein tyrosine kinase 7 (Ptk7) are candidate genes for growth and development of basic tissues of the palatal organ. Furthermore, taste-related genes such as fgfrl1, fgf8a, fsta and notch1a were also identified, which may be involved in the development of taste buds of the palatal organ. The transcriptome data obtained in this study provide insights into the understanding functions and development mechanisms of palatal organ, and potential candidate genes that may be related to the genetic modulation of head size of bighead carp.

Impact of Enzymatic Hydrolysis Using Two Proteases on Functional, Structural, and Antioxidant Properties of Protein Hydrolysates Derived from Fresh and Microwave-dried Substrates of Bighead Carp (Hypophthalmichthys Nobilis)

Impact of Enzymatic Hydrolysis Using Two Proteases on Functional, Structural, and Antioxidant Properties of Protein Hydrolysates Derived from Fresh and Microwave-dried Substrates of Bighead Carp (Hypophthalmichthys Nobilis)

Species-specific bioaccumulation and risk prioritization of psychoactive substances in cultured fish

Psychoactive substances are becoming new concern in environmental research with their increasing applications and the potential threats to fishery production as these substances could alter the behavior of fish and consequently affect the yield and quality of cultured fish. In this study, the accumulation and risk of twenty psychoactive substances were investigated in five species of cultured fish in Eastern China. The results showed that the total concentrations of these twenty psychoactive substances ranged from 0.15 to 0.92 ng mL−1 in the plasma among the five species of cultured fish with an order of perch > crucian carp > bighead carp > grass carp > silver carp. Diazepam (DIAZ) and methamphetamine (MAMP) were identified as the most frequently detected compounds, which were found in 100% and 93% of the samples with a median concentration of 0.15 and 0.12 ng mL−1 in the plasma, respectively. Although all of the psychoactive substances posed low or negligible risk, species-specific analysis of risk prioritization revealed that alprazolam, MAMP, temazepam and DIAZ exhibited the greatest potentials of hazard to all species of the cultured fish but with a species-dependent variation. These findings suggest that the adverse effects of psychoactive substances on fishery production, especially on different species, should be considered.

Ammonia Toxicity in the Bighead Carp (Aristichthys nobilis): Hematology, Antioxidation, Immunity, Inflammation and Stress.

Ammonia is one of the main environmental pollutants that affect the survival and growth of fish. The toxic effects on blood biochemistry, oxidative stress, immunity, and stress response of bighead carp (Aristichthys nobilis) under ammonia exposure were studied. Bighead carp were exposed to total ammonia nitrogen (TAN) concentrations of 0 mg/L, 3.955 mg/L, 7.91 mg/L, 11.865 mg/L, and 15.82 mg/L for 96 h. The results showed that ammonia exposure significantly reduced hemoglobin, hematocrit, red blood cell, white blood cell count, and platelet count and significantly increased the plasma calcium level of carp. Serum total protein, albumin, glucose, aspartate aminotransferase, and alanine aminotransferase changed significantly after ammonia exposure. Ammonia exposure can induce intracellular reactive oxygen species (ROS), and the gene expression of antioxidant enzymes (Mn-SOD, CAT, and GPx) increases at the initial stage of ammonia exposure, while MDA accumulates and antioxidant enzyme activity decreases after ammonia stress. Ammonia poisoning changes the gene expression of inflammatory cytokines; promotes the gene expression of inflammatory cytokines TNF-α, IL-6, IL-12, and IL-1β; and inhibits IL-10. Furthermore, ammonia exposure led to increases in stress indexes such as cortisol, blood glucose, adrenaline, and T3, and increases in heat shock protein 70 and heat shock protein 90 content and gene expression. Ammonia exposure caused oxidative stress, immunosuppression, inflammation, and a stress reaction in bighead carp.

Estimation of heritabilities and quantitative trait loci for growth traits of bighead carp (Hypophthalmichthys nobilis)

Estimation of heritabilities and quantitative trait loci for growth traits of bighead carp (Hypophthalmichthys nobilis)

Comparative genomics studies on the stk gene family in vertebrates: From the bighead carp (Hypophthalmichthys nobilis) genome

The mammalian sterile 20-like (MST) family belongs to the serine/threonine protein kinase (STK) superfamily and participates in a variety of biological processes, such as cell apoptosis, polarity, migration, immune regulation, inflammatory responses, and cancer. In the economically important bighead carp (Hypophthalmichthys nobilis), the STK gene family and immune-related biological functions may be helpful in increasing its economic yield. However, the comprehensive role of STKs in the bighead carp remains unclear. In this study, the five stk sequences from the bighead carp were divided into two classes: stk3/4 and stk24/25/26. Gene structure and motif prediction analyses confirmed that stk is conserved in the bighead carp. Compared to 26 other vertebrate species, teleosts (including bighead carp) possess more stk members because of teleost-specific whole-genome duplication. Synteny analysis revealed that stk3, stk24, stk25, and stk26 have been relatively conserved in bighead carp during evolution. Meanwhile, stk4 was lost in most Cyprinid species, including bighead carp, during evolution. RNA-seq data revealed that STK expression was associated with various pathogens, and the expression of these STKs (Hnstk3, Hnstk24a, Hnstk24b, Hnstk25, and Hnstk26) was different in seven tissues of bighead carp. In addition, we showed that STK expression levels were dramatically altered in the head kidney and that stk24 was involved in defense against Aeromonas hydrophila. This study provides a molecular basis for the analysis of stk function in bighead carp, and can be used as a reference for further phylogenomics.

WhoseEgg: classification software for invasive carp eggs.

The collection of fish eggs is a commonly used technique for monitoring invasive carp. Genetic identification is the most trusted method for identifying fish eggs but is expensive and slow. Recent work suggests random forest models could provide an inexpensive method for identifying invasive carp eggs based on morphometric egg characteristics. While random forests provide accurate predictions, they do not produce a simple formula for obtaining new predictions. Instead, individuals must have knowledge of the R coding language, limiting the individuals who can use the random forests for resource management. We present WhoseEgg: a web-based point-and-click application that allows non-R users to access random forests via a point and click interface to rapidly identify fish eggs with an objective of detecting invasive carp (Bighead, Grass, and Silver Carp) in the Upper Mississippi River basin. This article provides an overview of WhoseEgg, an example application, and future research directions.

Uncovering quality changes of salted bighead carp fillets during frozen storage: The potential role of time-dependent protein denaturation and oxidation

This study aimed to find the specific relationship between quality traits and myofibrillar proteins (MPs) alteration of salted fish during frozen storage. Protein denaturation and oxidation occurred in frozen fillets, with the denaturation occurring before oxidation. In the pre-phase of storage (0-12 weeks), protein structural changes (secondary structure and surface hydrophobicity) were closely related to the water-holding capacity (WHC) and textural properties of fillets. The MPs oxidation (sulfhydryl loss, carbonyl and Schiff base formation) were dominated and associated with changes in pH, color, WHC, and textural properties during the later stage of frozen storage (12-24 weeks). Besides, the brining at 0.5 M improved the WHC of fillets with less undesirable changes in MPs and quality traits compared to other concentrations. The 12 weeks was an advisable storage time for salted frozen fish and our results might provide an available suggestion for fish preservation in aquatic industry.

Predicting the age at maturity of Asian carp using air temperature

AbstractAsian carp (bighead carp, Hypophthalmichthys nobilis; grass carp, Ctenopharyngodon idella and silver carp, H. molitrix) are a group of invasive species that are predicted to cause ecological effects if they invade the Great Lakes basin. Although Asian carp age at maturity is known to be an important factor in the risk of establishing a population, there is relatively little maturity data for North America. We found that air temperature can be used to predict the age at maturity of Asian carp. Nonlinear regressions using mean annual air temperature and annual degree days to predict age at maturity explain 60% and 62% of the variation respectively. These models predict that maturation is possible in locations that were previously excluded from Asian carp spawning range based on data from the Amur River. As expected, we find faster maturation in more southern areas of North America, although there are relatively large errors predicting age at maturity in the Mississippi River population. We conclude that due to the effect of faster maturation on population growth rates, southern Great Lakes locations (e.g. Lake Erie) may be at greater risk of faster population establishment.

Hydroacoustic survey on fish spatial distribution in the early impoundment stage of Yuwanghe Reservoir in southwest China

Understanding the fish community structure and spatial distribution characteristics is essential for appropriate reservoir fishery management, especially in the early impoundment stage of the reservoir, which could help in obtaining basic data and performing artificial adjustments to biological communities. On the basis of this concept, we conducted a survey of the fish community and distribution at the newly constructed reservoir in southwest China by using a combination of methods, including hydroacoustic survey and fish sampling. Fish sampling showed a single fish community structure (six species belonging to four families) assembled in the reservoir, and the dominant species was Pseudorasbora parva which accounted for 98.79% of the fish population. In the hydroacoustic survey, the average fish density was 318.7 ± 256.1 individuals/1,000 m2. Irregular distribution of the fish was observed in the horizontal direction. The fish densities in the head area, middle area, and tail area of the reservoir were 168.5 ± 60.1, 306.8 ± 124.7, and 696.4 ± 288.9 individuals/1,000 m2, respectively, which showed a trend of increase in fish density with an increase in distance from the dam. More than 97.3% of the fish in the vertical direction were distributed in the water layer of depth 0 to 12 m. The average total length of fish was 75.4 mm, and the mean fish biomass in the reservoir was approximately 984.8 g/1,000 m2. According to Pearson correlation analysis, the main factors affecting the spatial distribution of fish were water depth, water temperature, dissolved oxygen, total nitrogen, and plankton density. Our results suggested that the fish community structure should be adjusted by releasing native carnivorous fish to control the abundance of small fish. Moreover, filter-feeding fish such as silver carp and bighead carp should be released in the reservoir to control the plankton community; this will enable the maintenance of the reservoir ecosystem in a healthy state while increasing the economic benefits to the local area.

Grass Carp Reproduction in Small Tributaries of Harry S. Truman Reservoir, Missouri: Implications for Establishment in Novel Habitats

AbstractSubstantial work has been conducted to estimate the river length required for recruitment of invasive Grass Carp Ctenopharyngodon idella and bigheaded carps (Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix); however, the distance upstream and size of stream required for spawning remain unclear. Adult Grass Carp are regularly captured in Harry S. Truman Reservoir, Missouri, although there have been only unconfirmed sightings of Silver Carp. Fertile diploid Grass Carp are used legally for vegetation control in Missouri; however, it is uncertain whether Grass Carp in Harry S. Truman Reservoir are the result of natural reproduction or escapees. We used ichthyoplankton tows and environmental DNA (eDNA) to investigate which carp species were present in the reservoir basin and to determine whether these carps were spawning in reservoir tributaries. Grass Carp eggs were collected in four of five tributaries during June 2014. We did not detect eggs, larvae, or eDNA of Bighead Carp or Silver Carp. The occurrence of Grass Carp eggs generally coincided with rapid increases in discharge and turbidity. These tributaries may be the smallest rivers worldwide in which spawning of Grass Carp has been documented. We infer from the developmental stages captured and the distance from the reservoir that sufficient river length exists for egg survival. These results have broad implications concerning the establishment of Grass Carp in other novel habitats, including other reservoirs and lake basins, smaller rivers, and the Laurentian Great Lakes ecosystem.

Non-native freshwater fish from drainages of Rio Grande do Sul State, Brazil

The present study catalogues exotic and allochthonous fish species found in the three main freshwater river drainages of Rio Grande do Sul State using records of scientific collections and literature, and discusses the main impacts caused by their introduction in natural environments. Ten exotic species are found in the area, i.e., Clarias gariepinus, Coptodon rendalli, Ctenopharyngodon idella, Cyprinus carpio, Hypophthalmichthys molitrix, Hypophthalmichthys nobilis, Ictalurus punctatus, Micropterus salmoides, Oncorhynchus mykiss and Oreochromis niloticus, belonging to five orders, nine genera and seven families. These fishes are native from African, Asian, European and North American countries. The eight allochthonous species, i.e., Acestrorhynchus pantaneiro, Hoplerythrinus unitaeniatus, Hoplias lacerdae, Megaleporinus macrocephalus, Piaractus mesopotamicus, Pachyurus bonariensis, Serrasalmus maculatus, and Trachelyopterus lucenai, belong to three orders, eight genera, and six families, are native from the Río La Plata basin, that includes the Río Uruguay, and have been all registered in the Laguna dos Patos. Two of these species are further recorded in the Rio Tramandaí system (A. pantaneiro and T. lucenai). The study also presentes a brief history of the first records of exotic species in the state and in the country, and their main vectors of introduction. According to the records of exotic species in scientific collections, the two exotic species with the highest number of records in the country are tilapias Coptodon rendalii (508 records) and Oreochromis niloticus (376 records), and most records occurred in the last two decades. The two carps Cyprinus carpio and Ctenopharyngodon idella are the only exotic species recorded in the three main drainage basins of the state. In addition, we warn about the importance of studies about the biology and negative impacts of exotic species over native species on the understanding of management in wild environments.

Novel ACE inhibitory peptides derived from bighead carp (Aristichthys nobilis) hydrolysates: Screening, inhibition mechanisms and the bioconjugation effect with graphene oxide

The ACE inhibitory peptides have been characterized from the enzymatic digestion product of bighead carp protein and bioconjugated with graphene oxide (GO) to enhance its activity. The results showed that aspartic acid and glutamic acid had the highest levels in ultrafiltration fractions (<5 kDa), where eight potential ACE inhibitory peptides were also identified (ADSNHKAF, KLWHHTF, LLRLHF, PPSEPTKL, VEKFPLF, YLRLHF, YYKLKPLL, YYKLKPML). Among the eight peptides, YLRLHF showed the best ACE inhibitory activity (IC50 = 121.90 μM) and was a competitive inhibitor. Molecular docking experiments showed that YLRLHF formed four hydrogen bond interactions in the ACE protein pocket, coordination bonding with Zn2+, and π-π conjugation interactions to His421. GO elevated the ACE inhibitory activity of YLRLHF (at 0.1 mg/mL) from 43.36% to 51.72%. The structural characterization results obtained from FI-IR, XPS, SEM, and TEM demonstrated the successful combination of GO and YLRLHF. Additionally, biocouples of ACE inhibitory peptides from bighead carp proteins with GO might be potential candidates for future functional foods and antihypertensive drugs.

Insight into the protein oxidation impact on the surface properties of myofibrillar proteins from bighead carp

The objective of this study was to elucidate the influence of oxidative modifications of myofibrillar proteins (MPs) on their surface properties. Oxidative modifications (deamination, formation of disulfide bonds and Schiff bases), particle size, net surface charge, and binding ability of volatiles (2-enthylfuran, 1-octen-3-ol, hexanal, and octanal) of oxidized MPs was measured. Molecular docking of volatiles with actomyosin was performed using Qvina-W program and the specific oxidative modifications (monoxidation and deamination) of MPs were determined using LC-MS/MS. Results showed that oxidation of Cys (forming sulfinic, sulfonic, sulfenic acid, and disulfide bonds), monoxidation of Ala, Lys, Glu, and Asn, and deamination of Lys changed the surface properties of oxidized MPs including enhanced surface hydrophobicity and decreased affinity to volatile compounds and water. Overall, this study gives evidence of how protein oxidation affects the properties of MPs and therefore deteriorates fish meat quality.

A combined survey and exposure study reveals the distribution characteristic of chromium in fish head.

In this study, the content of chromium (Cr) in three main edible tissues (dorsal muscle, ventral muscle, and head) of 14 different fish species was determined. As expected, Cr level in fish head is generally higher than that in fish muscle. To elucidate the deposition of Cr in the fish head, bighead carp (Hypophthalmichthys nobilis) was chosen as the model fish and a 14-day-exposure experiment of 1 mg/L Cr was subsequently conducted. The fish head was divided into 7 parts, and the results showed that, in different parts of the head, Cr was significantly accumulated in the brain, the muscle after gills, and the muscle of others, and the bone after the fish was exposed to 1-mg/L Cr for 14 days. Additionally, the health risk assessment showed that there was no potential non-carcinogenic risk of consuming the dorsal muscle, the ventral muscle, and the head of the 14 fish species to children, teenagers, and adults as the THQ values were less than 1. However, there was potential carcinogenic risk of consuming the fish head for adults in the 14 fish species. It is worth noting that, in the exposure experiment, the consuming of the lips and the bone of fish head also posed potential carcinogenic risk to adults while there was no potential risk of consuming the total fish head. Overall, compared to the fish muscle, the fish head usually had a high accumulation of Cr, and the Cr was mainly deposited in the position of the bone, which may pose potential carcinogenic risk to adults. Thus, the potential health risk of consuming the fish head is mainly associated with the content of the bone in the head, and, in the health risk assessment, the influence of the bone in the head should be considered, which may overstate the risks as fish head bone is usually not to be eaten.

FISH FARMING PRACTICES AND DISEASE OCCURRENCE IN THE FISH FARMS OF DHANUSHA DISTRICT, NEPAL

Dhanusha is one of the leading fish producing districts in Nepal and the fish farming is increasing in the district to establish the district as a ‘Fisheries center’. However, with the increasing fish farming and intensity, a number of diseases find their way to the farm which may hinder the progress of fish farming. Present study was carried out to assess the fish farming practices and the disease occurrence across the fish farms of Dhanusha district. Questionnaire-based personal interviews were conducted with 64-fish farmers selected from all over the district using simple random sampling. Majority of the respondents were males (89.1%), in the active age group of 30-50 years (71.9%), with average experience of more than 15 years (39%) in fish farming. The widely adopted farming system was Carp polyculture, however, some of the farmers also culture other species like Pangas, African catfish, Rupchand, Puntius etc. Only earthen ponds were common with water depths of 5-7 ft (54.7%). Majority of the respondents relied on private hatcheries (34.4%) for fish seeds and the most common stocking size was fingerlings (42.2%) and fry (29.7%). The major source of information and technical support for the farmers were successful farmers (82.8%) and government offices (73.4%). Approximately 65.6% of the farmers had received trainings on fish production and disease management. The most common feed materials were mustard oil cake (100%); rice bran (96.9%) and commercial pellet feed (54.7%). Cattle dung (87.5%); poultry manure (28.1%) and Urea/DAP (95.3%) were the major fertilizers used by the farmers. The most prevalent fish disease was Argulosis (96.9%), Lernaea (90.6%) and EUS (85.9%), but asphyxiation (82.8%) caused the reportedly highest mortality of 346.1±305.5 Kg/ha. Similarly, the most susceptible species to disease was Naini (65.6%) followed by silver carp (49.0%) and bighead carp (34.0%), while the least infected species was Grass carp (0.8%). Winter (70.3%) was reported to be the main season for the occurrence of fish diseases in Dhanusha district. The average B/C ratio in pond aquaculture in the study area was 1.36.

Influence of the Enzymatic Hydrolysis Using Flavourzyme Enzyme on Functional, Secondary Structure, and Antioxidant Characteristics of Protein Hydrolysates Produced from Bighead Carp (Hypophthalmichthys nobilis)

In the current study, bighead carp fish were used in conjunction with the flavourzyme enzyme to obtain (FPH) fish protein hydrolysates. The optimum conditions of the hydrolysis process included an enzyme/substrate ratio of 4% and a temperature of 50 °C and pH of 6.5. The hydrolysis time was studied and investigated at 1, 3, and 6 h, and the (DH) degree of hydrolysis was recorded at 16.56%, 22.23%, and 25.48%, respectively. The greatest yield value was 17.83% at DH 25.48%. By increasing the DH up to 25.48%, the crude protein and total amino acid composition of the hydrolysate were 88.19% and 86.03%, respectively. Moreover, more peptides with low molecular weight were formed during hydrolysis, which could enhance the functional properties of FPH, particularly the solubility property ranging from 85% to 97%. FTIR analysis revealed that enzymatic hydrolysis impacted the protein's secondary structure, as indicated by a remarkable wavelength of amide bands. Additionally, antioxidant activities were investigated and showed high activity of DDPH radical scavenging, and hydroxyl radical scavenging demonstrated remarkable activity. The current findings demonstrate that the functional, structural, and antioxidant characteristics of FPH might make it an excellent source of protein and suggest potential applications in the food industry.

Evolution of fish community structure, cause analysis and implications for &lt;i&gt;ex-situ&lt;/i&gt; conservation of Yangtze finless porpoise in Tian-e-Zhou Oxbow of Yangtze River

长江天鹅洲故道是长江江豚首个迁地保护区，其中充足而适口的饵料鱼类资源是长江江豚种群健康发展的保障。为此，根据2017年10月-2021年4月对长江天鹅洲故道进行的7次鱼类调查数据，结合禁捕前的历史数据，对其鱼类群落结构演变进行了分析，并针对长江江豚饵料鱼的供应状况对天鹅洲故道内鱼类资源管理提出了建议。调查期间，共采集到鱼类57种，其中，蒙古鲌（Culter mongolicus）、鲢（Hypophthalmichthys molitrix）和鳙（Aristichthys nobilis）等大中型鱼类生物量明显增加，而䱗（Hemiculter leucisculus）和似鳊（Pseudobrama simoni）等小型鱼类生物量呈现下降趋势。鱼类群落优势种逐渐由太湖新银鱼（Neosalanx taihuensis）、短颌鲚（Coilia brachygnathus）和䱗等小型鱼类转变为鳙、蒙古鲌和拟尖头鲌（Culter oxycephaloides）等大中型鱼类，尤其是新近出现的拟尖头鲌种群发展迅速。同时，短颌鲚和䱗等小型鱼类的体重在减小，而鲢、鳙等大中型鱼类规格在持续提高。长江江豚以小型鱼类和大中型鱼类的幼鱼为食，其资源下降将威胁长江江豚种群的维持和发展。为保障天鹅洲故道内长江江豚的食物供应，建议适当地捕捞鲢、鳙、蒙古鲌和拟尖头鲌，减缓鲢、鳙对小型鱼类的食物竞争压力，以及降低蒙古鲌和拟尖头鲌对小型鱼类的捕食压力；同时丰水期加强故道与长江的连通，引入更多长江干流繁殖的小型鱼类资源；并通过建设人工鱼巢以改善故道内䱗等产粘性卵小型鱼类的繁殖条件，增加小型鱼类资源量。;Tian-e-Zhou Oxbow is the first habitats for the ex-situ reserve established for the Yangtze finless porpoise. The rich and abundant forage fish resources are the guarantee for the healthy development of the Yangtze finless porpoise population. Therefore, the change of fish community structure was analyzed with combined of seven fish surveys data in Tian-e-Zhou Oxbow of Yangtze River from October 2017 to April 2021 and historical data before the fishing ban. In view of forage fish of Yangtze finless porpoise, some suggestions were provided for the scientific management of fish resources in Tian-e-Zhou Oxbow. During the investigation, 57 fish species were collected. The biomass of large and medium-sized fish such as Culter mongolicus, silver carp and bighead carp increased significantly while the biomass of small-sized fish such as Hemiculter leucisculus and Pseudobrama Simoni showed a declining trend. The dominant fish species gradually changed from small-sized fish such as Neosalanx taihuensis, Coilia brachygnathus and Hemiculter leucisculus to large and medium-sized fish such as bighead carp, Culter mongolicus and Culter oxycephaloides, in particular, the newly emerged Culter oxycephaloides population developed rapidly. Meanwhile, the body-weight of small-sized fish such as Coilia brachygnathus and Hemiculter leucisculus was decreasing, but the body-weight of large and medium-sized fish was increasing. Because the Yangtze finless porpoise feeds on the small-sized fishes and juveniles of large and medium-sized fishes, the decline of their food resources would threaten the maintenance and growth of the Yangtze finless porpoise population. In order to ensure food supply for the Yangtze finless porpoises in Tian-e-Zhou Oxbow, it suggested that rational capture of silver carp, bighead carp, Culter mongolicus and Culter oxycephaloides should be taken into consideration in order to reduce the food competition pressure of silver carp and bighead carp and the predation pressure of Culter mongolicus and Culter oxycephaloides on small-sized fishes. Besides, another measures to increase the small-sized fish resources like strengthening the connectivity of the oxbow with Yangtze River in the wet season to introduce more small-sized fish resources from Yangtze River and laying artificial fish nests in the oxbow to improve the breeding conditions for the small-sized fish species with adhesive eggs such as sharply should be carried out.

HYDRO-ECOLOGICAI CONDITION OF LAKE LYMAN (DVS RP "LYMANSKE" OF KHARKIV REGION)

A comparative analysis of the hydro-ecological state of Lake Lyman (DVSRP "Lymanske" of the Kharkiv region) of the cooling reservoir of the Zmiyivska TPP (Siverski Dinets basin) was carried out for the study of ecological and genetic features of white (Hypophthalmichthys molitrix) and variegated (Aristichthys nobilis) carp using ISSR DNA markers during 2019-2020. The ecological state of water bodies is presented, the species composition of the biota, the natural fodder base and the factors influencing the environment on the conditions of aquaculture are defined; the ecological conditions of growing a population of different age groups of variegated (Aristichthys nobilis) and white carp (Hypophthalmichthys molitrix) in the conditions of the Lymanske DVSRP of the Kharkiv region were studied in 2019. The studied phytoplankton shows a rather significant increase in biomass compared to previous research results (1984-2010). A significant increase in the number of phytoplankton is also evidenced by the fixation of floating masses of phytoplankton in the reservoir with a layer of up to 2-3 cm, among which blue-green algae (Cyanophyta), dinophyta (Dinophyta), and diamond algae (Bacillariophyta) predominated in number. The zooplankton of Lake Lyman was represented by rather widespread forms of three main groups: Rotifera, Cladocera, Copepoda. The ichthyofauna of the cooling pond of the Zmiivskaya TPP, which now includes 28 species of fish from 8 families, was studied. The main factors in the formation of the composition of fish in the cooling reservoir are the thermal load of the station, fishing activity and regular supply of river water to the reservoir. Changes in the composition of the fish fauna in recent years are due to the massive spread of evribiont fish-intervenors (needle fish, stickleback), a decrease in the power plant's working capacity (chub fish, gustera, or whitefish), as well as the release of fish from cages when the latter are broken.