Abstract:To assess fish distribution characteristics in Lake Bosten at different seasons and spatial scales as well as the status of fish resources, we conducted lake-wide cruise surveys using a split-beam echosounder (Simrad EY60, 120 kHz) from April to October in 2019. We quantified the spatial and temporal variations in fish density, size composition, and horizontal and vertical distribution. The results showed that fish densities in Lake Bosten in spring, summer, and autumn were 709±141, 8783±2611, and 743±499 ind/hm² , respectively, with mean target strengths (TS) of −52.95, −59.91, and −57.73 dB, respectively. In the horizontal dimension, fish distributed in both the littoral zone and open water area in spring and autumn, and more frequently in the littoral zone and macrophytic area in summer. In the vertical dimension, fish densities decreased with water depth below 3 m in spring, summer, and autumn. The target intensity showed a trend toward increasing with water depth in both the spring and autumn. In summer, the target intensity gradually increased with water depth between 3 and 12 m, while it decreased at water depth greater than 12 m. It is assumed that the spatial and temporal distribution of fish in Lake Bosten is related to factors such as reproduction, growth, and fishing. This study can provide basic data for fish conservation and the rational utilization of fishery resources in Bosten Lake, as well as a scientific basis for lake ecosystem management.

Abstract:To investigate the fish community structure and the factors influencing it in the Ulungur Lake, we collected fish samples using multi-mesh composite gill nets from 2019 to 2021. We identified 22 species in spring, summer, and autumn, belonging to four orders and six families, with seven historical indigenous species accounting for 31.8% of the total. Cyprinidae had the highest percentage of total species, with 15 species accounting for 68.2%. Throughout the year, Rutilus rutilus and Abramis brama were the dominant species in the Ulungur Lake, with Pinkas relative importance index (IRI) values of 7355.28 and 765.65, respectively. The dominant species in the Buluntuohai Lake were Rutilus rutilus and Abramis brama throughout the year, while in the Jili Lake, they were Rutilus rutilus, Perca fluviatilis, and Abramis brama. Calculation results of diversity indexes showed that the Shannon-Wiener index (H′), Margalef index (D), and Pielou index (J′) of fish communities were 0.91–1.76, 0.24–0.54, and 0.23–0.45, respectively. All of the diversity indexes H′, D, and J′ in spring were significantly lower than those in summer and autumn, and the Buluntuohai Lake had slightly higher diversity indexes than the Jili Lake. The analysis of the ABC curve showed that the abundance curve was generally above the biomass curve, and the statistical values of W ranged from –0.104 to –0.371. The disturbance degree was the highest in autumn (W=–0.226), followed by spring (W=–0.2), and the lowest in summer (W= –0.104). Additionally, the disturbance degree in Jili Lake (W=–0.307) was significantly higher than that in Buluntuohai Lake (W=–0.191). The redundancy analysis (RDA) showed that the fish community structure of Buluntuohai Lake was primarily affected by water depth, nitrate nitrogen, and water temperature, which affected the habits of fish breeding and feeding. In contrast, in Jili Lake, chlorophyll a and total nitrogen mainly affected the fish community structure, and the distribution of small omnivorous fish was positively related to the concentration of chlorophyll a and nutrients. This study found that the fish community structure in Ulungur Lake showed a trend of simplification of dominant species, miniaturization of fish, and decline of biodiversity.

Abstract:The reproductive strategy of Triplophysa yarkandensis in the Qarqan River was investigated based on 544 samples collected from 2019 to 2021. The study analyzed the breeding population composition, breeding period, first maturity, spawning type, fecundity, and other characteristics. The results revealed that the breeding population of Triplophysa yarkandensis ranged from 2 to 9 years old, with a male–female ratio of 1.16∶1, belonging to the second type (P=K+D, K＞D). The observed body length and age at first sexual maturity were as follows: female, 111.0 mm, 2 years old; male, 79.0 mm, 2 years old. The first sexual maturity body length (SL₅₀) and age (A₅₀) were as follows: female, 123.2 mm and 3.16 years old; male, 90.9 mm and 2.95 years old. Based on the appearance time and proportion of different gonad development stages, gonad maturity coefficient, and egg diameter distribution, it is inferred that Triplophysa yarkandensis is a batch spawning type, and the breeding period is from March to August, with a peak breeding period from April to June. The average absolute fecundity was (61407±46143) grains, and the average relative fecundity was (743.87±321.78) grains/g. Compared with other water bodies, the Triplophysa yarkandensis population in the Qarqan River had a larger average body length, average body weight, and first sexual maturity body length; a higher absolute fecundity; and a lower relative fecundity. The distinctive reproductive strategy of the Triplophysa yarkandensis population in the Qarqan River can offer fundamental data support for the protection of its resources.

Abstract:To effectively utilize the abandoned saline-alkali water in Xinjiang and establish a model of inland saline–alkali water fishery breeding, we conducted a study from April to September 2022 at Swan Lake of the Fourteenth Regiment in Alar City, Xinjiang. We collected water and fish samples every 30 d to analyze the changes in physical and chemical water quality indices, growth trends, and nutritional components of Cyprinus carpio, Carassius auratus, Ctenopharyngodon idella, and Triplophysa yarkandensis under pond ecological farming. The results indicated that the concentrations of Sal, Alk, Na⁺ , K⁺ , Ca²⁺, Mg²⁺, Cl^– , SO₄ ^2–, CO₃ ^2– and HCO₃ ^– in Swan Lake decreased significantly in July (P＜0.05), and there were no significant changes in Cu²⁺ concentration (P＞0.05). The specific growth rate (SGR) and weight gain rate (WGR) of Cyprinus carpio, Carassius auratus, and Ctenopharyngodon idella were lower than those of Triplophysa yarkandensis under this breeding mode. The moisture, crude protein, crude ether extract, and crude ash contents in the muscle of Cyprinus carpio, Carassius auratus, and Ctenopharyngodon idella were 75.32%–76.13%, 17.79%–22.35%, 2.74%–4.25%, and 1.67%–4.45%, respectively. The content of delicious amino acids (DAA) in the muscle of the three types of freshwater fish was significantly higher when cultured in saline-alkali water than in freshwater (P＜0.05); the essential amino acids (EAA)/total amino acids (TAA) and EAA/non-essential amino acids (NEAA) in the muscles of Cyprinus carpio and Carassius auratus were following the ideal model of the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO). The eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) contents in the muscles of the four kinds of fish were high, owing to the dietary sources of high quality protein and polyunsaturated fatty acids (PUFA). Principal component analysis indicated that the amino acid and fatty acid composition of Triplophysa yarkandensis was significantly different from that of the three major freshwater fishes (P＜0.05). The results showed that the growth rate of bulk freshwater fish was slow under the ecological breeding mode of saline–alkali ponds in Xinjiang, and the nutrient composition of the four kinds of fish was balanced, owing to the dietary source of high quality protein and PUFA. Our study highlights that saline-alkali aquaculture can improve the nutritional quality of bulk freshwater fish, promote effective utilization of saline-alkali water in Xinjiang, and achieve the sustainable development of saline-alkali water fisheries.

Abstract:Habitat restoration is a critical measure for conserving fishery resources and maintaining sustainable production. The habitat of juvenile fish in the Yangtze River Estuary has been seriously degraded. In this study, we aimed to identify the effects of tidal flat habitat restoration on fish community structure in the Yangtze River Estuary. Fish samples were collected in the spring, autumn, winter, and summer of 2021–2022 in the south branch of the Yangtze River Estuary. The study was conducted using fixed plug nets in the habitat restoration and control areas. The number of fish species, individuals, biomass, and diversity indices were compared between the restoration and control areas. A total of 27 fish species belonging to 21 genera in 8 orders and 9 families were collected during the study period, of which 22 species were collected in the restoration areas and 21 species in the control areas. The results showed that the total Margalef richness index (D) was 6.8, the total Shannon-Wiener diversity index (H′) was 4.92, the total Simpson simplicity index (C) was 2.47, and the total Pielou evenness index (J′) was 2.99. The overall biodiversity index was significantly higher in the restoration areas (17.18) than in the control areas (15.82). The frequency of fish larvae collected in the restoration areas (67%) was significantly higher than that in the control areas (44%) in the spring, indicating a preference for habitat restoration areas by juvenile fish in the restoration areas. These findings demonstrate that habitat restoration in the tidal flats could alleviate the ecological crisis of fish biodiversity in the Yangtze River Estuary and those restoration areas can provide nursery sites for juvenile fish. This study provides a reference for elucidating habitat restoration in fish nurseries in the tidal flats of the Yangtze River Estuary. In conclusion, enhancing the protection of fish habitats and restoring damaged wetlands is a crucial measure to protect fish resources in the Yangtze River Estuary.

Abstract:The migration and transformation of nitrogen in a seawater-constructed wetland treating Paralichthys olivaceus mariculture tail water was investigated using stable isotope technology. The study employed the mass balance method to quantify the contribution of different nitrogen removal pathways to overall nitrogen removal. showed that the compound vertical flow constructed wetland had a significant effect on nitrate nitrogen treatment, with a nitrogen removal rate of (92.81±1.21)% after 21 d of operation. The δ¹⁵N value of the coal residue layer was the lowest (203.58±2.87)‰, while the coral stone layer had the highest δ¹⁵N value (303.66±2.22)‰. Plants exhibited the best capacity for nitrogen uptake, with an average nitrogen content of (2.68±0.38)% and an average absolute abundance of (105.61±14.65) × 10^–3 mg/g. Microbial transformation was found to be the main nitrogen removal pathway, accounting for 60.77% of the nitrogen removal. This study provides effective data support for applying stable isotope technology to the construction of seawater-constructed wetlands and clarifies the nitrogen removal process.

Abstract:The large yellow croaker Larimichthys crocea, is a commercially important marine fish species that is susceptible to Cryptocaryon irritans in summer and mass mortality due to cold stress during overwintering. CuSO₄ is an effective and affordable treatment for C. irritans, but it causes Cu pollution in aquaculture water. This study investigated the effects of Cu acclimation on the antioxidant capacity, energy metabolism, and non-specific immunity of large yellow croaker under cold stress. Fish were pre-acclimated to 0 and 20 μg Cu/L for 7 d, and subsequently exposed to cold stress (10 ℃) for 6 and 24 h. The results showed that compared to the control group, the cold stress group showed oxidative damage via changes in the antioxidant system, energy metabolism, and immune system, as evidenced by increased reactive oxygen species (ROS), vacuolation rate of hepatocytes, chromosome coagulation, anaerobic metabolism, and reduced antioxidant capacity. Cu acclimation with low temperature stress alleviated cold stress-induced oxidative damage by improving antioxidant capacity, energy metabolism efficiency, and non-specific immunity, as evidenced by decreased vacuolation rates of hepatocytes, ROS, and lactic acid contents, and increased activities of glutathione peroxidase, catalase, ATP synthetase, succinate dehydrogenase, alkaline phosphatase, lysozyme, and contents of glutathione and ATP. Cu preacclimation can generate adaptive responses that enhance tolerance to low temperature stress, emphasizing the central role of hormesis.

Abstract:To investigate the regulation of glucose homeostasis in Micropterus salmoides, we cloned genes gp1, gp2, pepck1, pepck2, hk, pfk, and g6p encoding 878, 842, 635, 624, 918, 780, and 338 amino acid residues. We also examined the phylogenetic tree, tissue distribution, and effect of fasting on the expression of these genes. Results from multiple protein sequence alignments and phylogenetic analysis showed that these genes shared high levels of identity with their orthologs in other vertebrates. Tissue profiles of these genes revealed enrichment in the liver and muscle, but with unique tissue expression differences. For example, gp1 was highly expressed in the muscle, followed by the liver, and the lowest expression level was observed in the spleen. gp2 was also highly expressed in the muscle and abundant in the heart and liver. pepeck1 was mainly expressed in the liver and intestines, with the lowest mRNA levels in the brain, spleen, kidney, and adipose tissue. pepck2 was more significantly expressed in the liver and brain than in the other tissues, whereas the lowest mRNA levels were found in the spleen and gills. Additionally, hk and g6p were most abundantly expressed in the liver, and pfk in the liver and heart. The g6p gene was also the most abundantly expressed in the liver. The muscle, intestines, and adipose tissue were also enriched with an abundance of g6p. The highest expression levels of pfk were found in the liver and heart, followed by the intestines and gills. We examined the effect of fasting on the mRNA levels of these genes in Micropterus salmoides. The results showed that hepatic gp2, pepck2, and g6p mRNA levels were gradually up-regulated with increasing fasting time, peaking at 24 h after fasting. However, gp1, hk, and pfk exhibited diverse gene expression patterns, with transcription first increasing and then decreasing with the extension of fasting time, peaking at 6 h. Hepatic pepck1 was not significantly affected throughout the fasting period. In the muscle, gp1, gp2, and g6p mRNA expression increased significantly at 12 h, with pepck1 showing the lowest expression at 0 h and the highest expression at 12 and 24 h. After fasting for 24 h, pepck2 showed the highest mRNA level. Muscular hk and pfk showed a similar expression pattern with hepatic gp1, hk, and pfk, increasing and then decreasing with fasting time. Overall, these findings provide groundwork for future studies focusing on glucose homeostasis regulation in Micropterus salmoides.

Abstract:This study aimed to investigate the relationship between morphological traits and body weight and fillet yield in largemouth bass, with the goal of selecting individuals with a high weight gain rate and fillet yield. Largemouth bass widely used for breeding in China (Northern subspecies, YouLu1, YouLu3, and China-Taiwan) were selected for the experiment. Body weight (Y), fillet yield (Y_F), total length (X1), body length (X2), body height (X3), body thickness (X4), head length (X5), interocular distance (X6), eye diameter (X7), snout length (X8), caudal stalk length (X9), and caudal stalk height (X10) were measured. Correlation analysis, path analysis, coefficient of determination analysis, and multiple linear regression analysis were conducted to identify the morphological traits affecting body weight and fillet yield. The results show that total length (X1) and body height (X3) have the greatest influence on body weight, while caudal stalk height (X10), caudal stalk length (X9), body length/caudal stalk length (X2/X9), and body weight (Y) have the greatest influence on fillet yield. Multiple regression equations were constructed for each subspecies. and their influence on body weight and fillet yield were determined for four largemouth bass subspecies: Northern subspecies, YouLu1, YouLu3, and China-Taiwan. For the Northern subspecies, the regression equation for body weight was Y=–622.778+21.21X1+45.305X3+16.633 X8+17.431X10, and for fillet yield, it was Y_F=12.394+3.683X10+24.152X1/X2. The regression equation for YouLu1 was Y=–453.528+54.855X3+5.913X1+22.708X5+41.194X7 for body weight, and Y_F=69.985+3.144 X9–0.020 Y–24.844X1/X2 for fillet yield. The regression equation for YouLu3 was Y=–531.600+56.933 X3+12.502X1+28.466X8 for body weight, and Y_F=120.795–3.221X2/X9–41.856X1/X2–2.495X3/X10 for fillet yield. Finally, for China-Taiwan, the regression equation for body weight was Y=–660.952+20.889 X1+60.774 X3–10.605X5+21.372X4, and for fillet yield, it was Y_F=43.928+0.011Y+0.452X9. These equations enable the selection of largemouth bass with a high weight gain rate and fillet yield. In addition, the study suggests that largemouth bass with a slender body type index (2.60

Abstract:Replacement of fish meal with economic alternative ingredients in aqua-feed is one of the most important question in aquaculture in the past four decades. In this paper, we evaluated the potential of replacing fish meal with feather meal in large yellow croaker (Larimichthys crocea) diet, with emphasis on the roles of keratinase DP-100 and gamma irradiation to improve feather meal use in fish diets. We used a two-way experimental design. A diet containing 35% fish meal severed as basal diet (BD), and 30% of fish meal in diet BD was replaced with hydrolyzed feather meal (I0E0). In diet I0E0, 1% keratinase DP-100 was added (I0E1), or the hydrolyzed feather meal was replaced with gamma ray (γ) irradiated feather meal (I1E0), or 1% DP-100 supplementation and replacement of the hydrolyzed feather meal with γ-irradiated feather meal were performed in combination (I1E1). Large yellow croaker were fed with the test diets in experimental net pens (1 m×1 m×2 m) for 10 weeks. Initial body weight of the test fish was (19.7±0.2) g (±SD, n=15), and fish density was 40 fish per pen. The results showed that 1% DP-100 supplementation significantly affected (P＜0.05), while γ-irradiation did not obviously affect (P＞0.05), feed intake, final body weight (FBW) and weight gain. Feed conversion ratio (FCR), nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE), energy retention efficiency (ERE), condition factor, hepatosomatic index, viscerosomatic index, whole body composition, ratio of fish meal consumption to fish production (RCP), nitrogen waste and phosphorus waste were independent on DP-100 supplementation, γ-irradiation and their interactive effect (P＞0.05). The feed intake, FBW and weight gain were higher in fish fed diets I0E1 and I1E1 than in fish fed diets I0E0 and I1E0 (P＜0.05). The FBW and weight gain of fish fed diet BD was higher than those of fish fed diets I0E0 and I1E0 (P＜0.05), but did not significantly differ from those of fish fed diets I0E1 and I1E1 (P＞0.05). The RCP was lower in fish fed diets I0E0, I1E0, I0E1 and I1E1 than in fish fed diet BD (P＜0.05), while no significant differences were found in FCR, NRE, PRE, ERE, condition factor, hepatosomatic index, viscerosomatic index, whole body composition, nitrogen waste and phosphorus waste between fish fed diet BD and diets I0E0, I1E0, I0E1 and I1E1 (P＞0.05). This study indicates that 1% DP-100 supplementation benefited to improve feather meal as a fish meal substitute in large yellow croaker diet, while γ-radiation treatment did not play a positive role in increasing fish meal replacement level with feather meal. Dietary fish meal level for large yellow croaker could be reduced from 35.0% to 24.5% by adding 1% DP-100 and 8.5% hydrolyzed feather meal in combination.

Abstract:To identify a suitable diet for the cultivation of Daphnia carinata, an experiment was conducted to investigate the effects of different diets on the growth, reproduction, and population dynamics of D. carinata. Corn powder, yeast, Chlorella sp., Schizochytrium sp., Chlorococcum sp., and Nannochloropsis oculata were used as dietary sources. The nutritional composition of each diet, culture water quality, and bacterium count were also assessed. The results showed that the survival rate of D. carinata was highest when fed Chlorococcum sp. The Chlorococcum sp. and N. oculate groups had significantly higher first offspring times (4.0 d) compared to other groups, with the highest offspring number per female found in the Chlorococcum sp. group (375.2 ind). Conversely, the survival rate of offspring was significantly lower in the corn powder group than in the other groups. D. carinata treated with Chlorococcum sp. exhibited the highest net reproductive rate (R₀ , 293.3), and the mean generation time of D. carinata in the Chlorella sp. group (5.0 d) was significantly lower than that in other groups. Although there was no significant difference in intrinsic growth rate r_m and finite growth rate λ among the Chlorella sp., Chlorococcum sp., and N. oculate groups, all of them were significantly higher than those in the other groups. Correlation analysis between diet nutrition compositions and the growth, reproduction, and population dynamics of D. carinata showed that dietary protein content was significantly negatively correlated with time for first offspring but positively correlated with intrinsic growth rate, finite growth rate, net reproduction rate, and reproductive capacity. The dietary carbohydrate content was positively correlated with the time of first maturity. The dietary arachidonic acid (ARA, C20∶4n-6) content was significantly positively correlated with reproductive capacity, survival rate, and net reproductive rate. The dietary linoleic acid (C18∶2n-6) content was positively correlated with the time of first maturity but negatively correlated with the survival rate. The dietary oleic acid (C18∶1) content was extremely negatively correlated with the survival rate of D. carinata. In conclusion, the protein content, carbohydrate content, and fatty acid composition of the diet were the key factors affecting the culture effect of D. carinata. Among the six diets, Chlorococcum sp. was found to be more suitable for the cultivation of D. carinata.

Abstract:This study aimed to investigate the effects of dietary phytosterols on growth performance, digestion, antioxidant and immune responses, and hepatopancreas and intestinal morphology in Procambarus clarkii. Five diets were prepared by adding 0%, 0.10%, 0.19%, 0.38%, and 0.76% phytosterols to the basal diet, which were named CON, P1, P2, P3, and P4, respectively. The crayfish were cultured for six weeks, and their average body weight was (9.37±0.02) g. The results showed that the weight gain rate and specific growth rate in P1 and P2 were significantly higher than those in CON (P＜0.05), and the growth performance in P2 was the best. The protease activity in the gut in P3 was significantly higher than that in CON, while the lipase activity was significantly lower (P＜0.05). The acid phosphatase and alkaline phosphatase activities in P1 were the highest in the hepatopancreas, and the acid phosphatase and alkaline phosphatase activities in P2 were the highest in the hemolymph; however, there were no significant differences compared to those in CON (P＞0.05). As the phytosterol level increased, the total superoxide dismutase and catalase activity in the hepatopancreas and hemolymph increased, and the malondialdehyde content decreased. Compared with CON, the intestinal structure in P1 was improved. However, when the phytosterol level exceeded 0.10%, hepatopancreas and intestinal damage increased with the increase in the dietary phytosterol level. The expression of NF-κB in the hepatopancreas increased as the phytosterol level increased. The expression of Hsp70 in P1 was significantly higher than that in other groups (P＜0.05). In conclusion, 0.10%–0.19% dietary phytosterol could promote the growth and digestion of P. clarkii, improve the morphology of the intestinal and liver tissues, and enhance the antioxidant and immune responses of P. clarkii.