Abstract:In order to track the fishery resources in Haizhou Bay, we conducted preliminary studies on the community structure of fishery resources in the northern area of Haizhou Bay. The data were collected in bottom trawl surveys in May 2012 (spring). In the survey totally 51 species were collected including 33 species of fish, 14 species of crustaceans and 4 species of cephalopods. The range of the biomass distributions of fishery resources was 13.55−35.90 kg/h, with an average of 24.59 kg/h. The range of the number distributions of fishery resources was 1858−14844 ind/h, with an average of 8046.58 ind/h. The individual density of fishery resources was 65.58×10³−589.92×10³ ind/km², with an average of 297.24×10³ ind/km². The biomass density of fishery resources was 428.34−1420.16 kg/km², with an average of 919.09 kg/km². The dominant species were Syngnathus acus, Pholis fangi and Metapenaeopsis dalei. There were 15 important species including Callionymus kitaharae, Liparis tanakae, Lophius litulon, Heptacarpus rectirostris etc. The species richness (D), Shannon-Wiener diversity index (H′) and evenness index (J′) were calculated based on the survey data. D was 1.400−3.255, with an average of 2.471; H′ was 0.492−2.309, with an average of 1.857; J′ was 0.182−0.713, with an average of 0.596. The previous survey in 1980s showed that there were 150 species of fish in Haizhou Bay, therefore since then the diversity of fish species have greatly declined. The numbers of crustaceans and cephalopods species were also decreased compared to data (19 species of crustaceans and 6 species of cephalopods) from other researchers. The biomass and numbers of the main economical species were reduced. Small and low-value fish species and Metapenaeopsis dalei have gradually taken over the dominance. Tailfish (Trichiurus lepturus), an economical species, was not found. These phenomena may result from over-fishing and/or anthropogenic pollutions.

Abstract:The high sea fishing grounds of Patagonia Continental Shelf is rich in fishery resources. There have been reports on squid fishing in domestic fishery, but study on trawl resources has been lacking. In this study, we analyzed the dynamics of the environmental characters, the fishery resources, the species composition as well as the biology of the dominant species. This study was based on the monthly bottom trawl surveys between January and March in 2011. The fishing grounds (45°01′−46°53′ S, 60°07′−60°47′ W) of Patagonia Continental Shelf high seas had a flat bottom and the depth of water was 110−180 m. The weather condition was good during the survey. This area was suitable for bottom trawl. There was a thermocline and halocline at 20−80 m underwater. This area was located at the edge of Patagonian Continental Shelf Fisheries which was adjacent to the Falklands - Malvinas Continental Shelf Fisheries. Hence the catch composition had the combined characters of both fisheries. The trawling catch was composed of 11 economic species, and Argentine shortfin squid (Illex argentinus), rock cod (Patagonotothen ramsayi), Argentine hake (Merluccius hubbsi), Argentine anchovy (Engraulis anchoita) and the skates accounted for 92.26% of the total. The average relative resource index (RRI) was the lowest in January and the highest in March. The results suggested that these fisheries were suitable for bottom trawling; the northern and southern parts of the fishing grounds were very different in species composition and the resource density, and the northern part had a more diverse and abundant resource. The dominant mantle length of I. argentinus increased from January to March, but that of M. hubbsi did not change over time. The dominant body length of rock cods was shorter than the length when they first became sexually mature, and their length was only 110−130 mm in January. It was most likely that the majority of the catch in this survey were feeding migratory juveniles.

Abstract:The concentration of chlorophyll-a is an important index of phytoplankton biomass that can reflect the status of ocean primary productivity. According to the analysis on the physicochemical environmental factors that affect the concentration of chlorophyll-a, we may clarify the dominant factors of ocean primary productivity. Two monitoring stations were situated on the sea area in Jiangmen, Guangdong Province, China. The survey was conducted from March to November 2010 to determine chlorophyll-a, water temperature, salinity, pH, dissolved oxygen (DO), chemical oxygen demand (COD), phosphate, nutrient N and oil in two stations. According to the principal component analysis (PCA), the application of the partial least squares (PLS) regression solved the multiple regression analysis including the multiple correlations between the environmental factors with a high precision; it also established the mathematical model with fewer monitoring data. In the PLS regression, the monitoring data were normalized, and then used the variable importance in projection and T² ellipse fitting-aided analysis technique for extraction. The regression equation of station A was y = 0.0076x₁-0.0806x₂-1.2869x₃+ 0.1498x₄-0.1905x₅ 126.6x₆ 5.985x₇-0.3538x₈ 10.84. The regression equation of station B was y= 0.0781x₁ 0.5852x₂ 0.4773x₃-0.5661x₄-38.11x₅ 0.8501x₆-4.429. The eutrophic index of station A was 0.041, suggesting that the water of Chuandao sea area was oligotrophic. The eutrophic index of station B was 1.005, suggesting that the water of Shadi sea area was eutrophic. The results showed that the main effective factors of chlorophyll-a were nutrients N and phosphate in oligotrophic waters of Chuandao sea area, and that COD, DO and water temperature were the effective factors of the ocean primary produ¬ctivity in Shadi sea area.

Abstract:The breeding of fish species that tolerate saline-alkaline is of great importance in the usage of salinity-alkalinity water bodies and in the sustainable development of aquaculture industry. Due to their fast growth rate and excellent adaptability to different environments, Nile tilapia Oreochromis niloticus could be a good candidate for the saline-alkaline tolerance breeding. In this study we evaluated the tolerance and growth performance of three strains of juvenile Nile tilapia (Shanghai, Shandong and Hebei strains) in salinity-alkalinity water. During a 60-day culture experiment we compared the average growth rates of the three strains in different salinity-alkalinity water (S0A0, S10A0, S10A2, S10A4, and S10A6) and their median lethal saline/alkaline concentrations. The results showed that in the 96 h culture the median lethal salinities for juvenile Shanghai, Shandong, Hebei strain were 18.528 g/L, 20.347 g/L, and 19.342 g/L respectively; the median lethal NaHCO3 alkalinities were 8.827 g/L, 8.540 g/L, and 8.542 g/L respectively. For mixed salinity-alkalinity test, at salinity 10 the 96-h lethal alkalinity was 4.377 g/L for Hebei strain, 3.561 g/L for Shanghai strain, and 3.108 g/L for Shandong strain; at salinity 15, it was 2.144 g/L for Hebei strain, 2.183 g/L for Shandong strain, and 2.183 g/L for Shanghai strain (P>0.05). The alkaline tolerance of Nile tilapia at high salinity was significantly lower than that at low salinity (P<0.05). The growth experiment results showed that there was no significant difference in the average growth rate between S0A0, S10A0 and S10A2. However, the average growth rate decreased at S10A4 and was significantly lower at S10A6 (P<0.05). Hebei strain showed a higher growth rate than Shanghai and Shandong strains at S10A2, S10A4 and S10A6 (P<0.05). Our results should provide important clues about the suitable salinity and alkalinity of the culture water bodies and about the selected breeding of Nile tilapia.

Abstract:The sustained-release delivery system of human chorionic gonadotropin (HCG) has been considered as a good method to induce gonad maturation in cultured fish. Sodium alginate microsphere is a new type of sustained-release delivery system of Human Chorionic Gonadotropin (NaAlg-HCG). In this study we implanted the NaAlg-HCG into female goldfish at regular intervals and examined its effects on the gonadal development, the level of major sex hormone in serum, and the expression of genes associated with reproduction hormones. The serum hormone level was measured with Radiate Immuno Assay (RIA) and the gene expression was examined using RT-PCR. Initially most oocytes of female golden fish were at stage III. From the Day 6 to Day 21 after the implantation, the gonadosomatic index (GSI) of fish implanted with NaAlg-HCG was significantly higher than that of the control group (P<0.05). From the Day 6 to Day 30, the levels of both estradiol (E2) and testosterone (T) in the serum of NaAlg-HCG group were significantly higher than those of the control group (P<0.05). RT-PCR results showed that from Day 6 to Day 21, the relative expression level of CYP19A of the NaAlg-HCG group was significantly higher than that of the control group (P<0.05). From Day 14 to Day 30, the ERα mRNA in the gonad of the NaAlg-HCG group was significantly higher than that of the control group (P<0.05). There was no difference in the relative expression level of GH in the gonad between the NaAlg-HCG group and control (P>0.05), except for the 2nd day after the implantation of NaAlg-HCG (P<0.05). These results suggested that after one-time implantation of NaAlg-HCG, HCG could be released steadily and regularly in 21 days. During this period NaAlg-HCG significantly increased the gonadosomatic index (GSI), the level of sex hormone in the serum, and the relative expression of genes associated with reproduction. The sodium alginate microsphere-based sustained-release delivery system therefore could be a good candidate for hormone implantation.

Abstract:Northern pike (Esox lucius), one of the major indigenous economic fish in Xinjiang, belongs to the ferocious carnivorous cold-water fish family. With the fast development of artificial breeding, disease outbreak has raised. The outbreak of bacterial sepsis is one of the dominant diseases to Northern pike farming, causing huge economic losses in local aquaculture. In order to identify the etiology of the Northern pike, the liver and kidney samples of Northern pike were collected for the morphology observations, physiological and biochemical tests, and 16S rDNA sequence analysis. Nine dominant bacteria were separated, which belong to the Aeromonas hydrophila family (named PK001−PK009). The PCR specificity detection results indicated that the separated nine strains contained three mainly and widely studied virulence factors of A.hydrophila ahpA, hlyA and aerA with the frequency from zero to three, which leaded to the discrepancy of strains. The illness of artificial recurrent infection and natural case of E. lucius were similar, and the origin infection bacteria were separated and further confirmed with A. hydrophila infection. A. hydrophila is the main pathogenic bacteria that induce fish bacterial sepsis.

Abstract:In order to evaluate the effects of non-starch polysaccharide (NSP) enzymes in the seaweed Ulva pertusa-containing diets on the feed utilization of Siganus canaliculatus, we prepared six isonitrogenous and isolipid compound diets with 32% crude protein and 8% lipid. Diets without seaweed were used as control diet 1 (C1); diets that contained 15% seaweed powder were used as control diet 2 (C2); four other diets that contained 15% seaweed powder together with different levels of non-starch polysaccharide enzyme were used as experimental diets (T1−T4). S. canaliculatus juveniles were fed with these six diets for 8 weeks. We then compared their growth performance, the activities of digestive enzymes, and the apparent digestibility of nutrients, in order to determine the effects NSP and its optimal amount in the diet. The results showed that the weight gain rate, specific growth rate and protein efficiency rate in Groups T1−T4 were higher than those in Group C2, but displayed no significant difference from Group C1 (except for the protein efficiency in Group T4) (P>0.05). All six groups showed no significant differences in the body biochemical composition and activities of digestive enzymes in stomach, foregut and liver that included protease, amylase and lipase (P>0.05). The apparent digestibility coefficient of protein and the digestibility of dry matter in Groups T1−T4 were significantly higher than those in Group C2 (P<0.05). The whole body composition was similar between the seaweed groups and the control group. In terms of the amino acid and fatty acid composition in the dorsal muscles, seaweed groups showed no significant differences from the control, except that the levels of ALA, EPA, DPA, Tyr and Met in flesh were reduced in the seaweed groups, and the level of His was increased. These results indicated that the addition of NSP enzyme in seaweed-containing diets could improve the growth performance and feed utilization efficiency, and seaweeds in diet have little impact on the nutrition composition in the flesh.

Abstract:The relationship between the feeding strategy and the growth of sea cucumber Apostichopus japonicus has been an important issue in aquaculture, but the study on the optimized feeding frequency was rare. We conducted a 40-day experiment to identify the best feeding frequency and the mechanisms how feeding frequency affected the growth, the biochemical composition and the energy budget of sea cucumbers. The sea cucumbers were divided into four groups according to the feeding frequencies: F1 (1 time/day), F2 (2 times/day), F3 (3 times/day), and F4 (4 times/day). Each group had 3 duplicates. The artificial feed was made by authors themselves. During the experiment, the unfed feed and feces of sea cucumbers were collected then dried at 70℃. The food consumption, initial body weights and final body weights were recorded. The results showed that the F3 and F4 grew faster and their final body weights were significantly higher than those of F1 and F2 (P<0.05). Food consumption increased along with the feeding frequency. Food consumption of F4 was 3.67 g/(d•ind) which was the highest among all groups. Food consumption of F3 and F4 was significantly higher than that of F1 and F2 (P<0.05), but there was no significant difference between F3 and F4 (P>0.05). The food conversion efficiency increased along with the feeding frequency and it was 9.70% in F4, but the digestion rate showed the opposite trend. The feeding frequency did not much affect the biochemical composition of sea cucumbers. The remained food energy in feces was more than 50% of the total food energy in all 4 groups, and it was significantly lower in F1 and F2 than in F3 and F4 (P<0.05). The proportions of food energy consumed in respiration in F1 and F2 were higher than those in F3 and F4 (P<0.05). Our data suggested that the optimal feeding frequency was three times per day for sea cucumbers reared indoors. The poor growth performance of F1 may be caused by their high excretion and respiration expenditure in energy.

Abstract:Due to the rapid development of Tilapia exportation in China, a large number of fish processing by-products have been generated which are rich in collagen. Proper extraction of the collagen from the by-products could help alleviate environmental pollutions as well as improve the added value of the fish processing by-products. In this study we used Tilapia skin as the material and applied the orthogonal design and the single factor test to exam the efficiency of alkali method, acid method and enzyme method in the pretreatment of Tilapia skin, according to the skin yield, viscosity and gel strength. Through a set of experiments we first identified the best method among the three and then optimized the bleaching and extraction process, and at last we made a discussion about this study to provide guidance on the gelatin production using fish skin. The results showed that the enzyme method was the best for gelatin extraction. The process was as below: the fish skin was treated with 0.2% mixed enzyme solution at pH 3.5, and underwent enzymatic hydrolysis at 40℃ for 1 h; the skin was then blanched with 6% potassium permanganate solution for 3 h followed by further blanching with 1.5% oxalic acid solution for 45 min; the skin was then degelatinized at pH 5−6. The gelatin extraction process includes 3 heating steps: 60℃ for 2 h, 65℃ for 2 h, and 70℃ for 2 h before the final filtrated product was pooled. The filtrate was then concentrated to around 20% in the vacuum (≥500 mmHg) at the temperature ≤60℃. The concentrate was dried (water content <14%) at 60℃ and the final gelatin product was obtained after crushing. The yield of gelatin was 19.93% (wet basis), and the viscosity was 13.1 mPa•s, and the gel strength was 1034.3 g/cm2.

Abstract:Norovirus (NoV) is the most common pathogen of acute viral gastroenteritis worldwide, which causes serious issues on public health and food safety. Histo-blood group antigens (HBGAs) have been recognized as receptors of NoV. It has been reported that type A-like HBGA presents in oyster gastrointestinal cells and induces specific accumulation of NoV in oysters. Alpha-1,2-fucosyltransferase (FUT2) is one of the key enzymes required in the HBGA synthesis. However, studies on FUT2 in oysters and other aquatic animals have been lacking. In this study, we cloned the FUT2-like gene in oysters (Crassostrea gigas) using homologous gene sequence method, and also analyzed the expression of FUT2-like gene in five tissues, including hepatopancrea, adductor muscle, mantle, labial palp and gills. The FUT2-like cDNA has a full length of 1941 bp, including a180-bp 5-untranslated region (UTR), a 1086-bp open reading frame (ORF) that encodes a protein of 361 amino acids, and a 675-bp 3-untranslated region (UTR). The molecular evolution analysis showed that the FUT2-like gene in oyster should be categorized into the same branch as FUT2 genes in Mus musculus and other mammals. The expression pattern of FUT2-like gene was analyzed in 5 tissues mentioned above. The results showed that the mRNAs of this gene were expressed in all 5 tissues; the expression level in labial palp was significantly lower than that in the other 4 tissues. Our results indicated that A-like HBGA in oyster might have a similar biosynthesis pathway as Type A HBGA in human. Our study should provide insights into the molecular mechanism of the accumulation of NoV in oysters.

Abstract:To investigate the effects of various densities on the growth, physiology and water quality of adult turbot in a recirculating aquaculture system, the adult turbots with the initial average weight (580.9±44.65) g were cultivated at one of the following three stocking densities: low (14.30 kg/m2, Group A), medium (20.49 kg/m2, Group B), and high (31.32 kg/m2, Group C) for 120 days. The survival rate, weight change, food coefficient and blood lysozyme level, as well as the changes in total ammonia (TAN), nitrite nitrogen (NO2-N), and COD in aquaculture water were measured. The results showed that the stocking densities of A, B and C group were 30.09 kg/m2, 41.30 kg/m2 and 60.07 kg/m2, respectively at 120 days. The survival rates of three groups were all over 95%. The net weight gain in each group varied significantly (P <0.01) with the highest in Group C. Feed conversion rates (FCR) of cross the three groups were 0.73, 0.75 and 0.82, respectively, which were positively associated with stocking density. Blood lysozyme level in Group C was increased at 5 d; it began to decline at 20 d and then decreased markedly at 40 d compared with that in Group A (P<0.01). During the entire experiment, the recirculating aquaculture systems were stable and the stocking densities had significant effects on the TAN, NO2-N and COD of water quality index (P<0.05). The increase of the stocking density significantly increased water quality indexes; however, it did not exceed the fishery water quality standards.

Abstract:The current study investigated the early pigment accumulation and transformation process of Plectropomus leopardus and evaluated the effects of two feeding additives on growth and body color traits. The results indicated that larval eyespot pigment granules gradually increased at day 2, the white eyes became black, and the feeding behaviors appeared. The arborization melanin area extended on the back fin at day 3, and a melanocytes plexus appeared at the bottom of the spine. At 22 d, the row intermittent melanin spots appeared above the fish spine and the number of melanin spots reduced. The mouth, the base of the fins and both sides of the spine became pale yellow. At 28 d, the accumulation of yellow and red pigment of the juvenile was further increased, which were surrounded by lots of red pigment spots. The fish had vivid orange color. At 30−33 d, the surface of both sides was covered with dense black and orange spots. The chunks of the spots were disappeared under the spine except a large melanin spot at the bottom of the caudal. The spirulina powder and astaxanthin had similar and significant effects on the full length and body weight of Plectropomus leopardus (P<0.05) at day 15. At day 30, 9% but not 3% and 6% of spirulina powder had significant effects on the body weight (P<0.05). Compared to the control, all astaxanthin treatments (except the 0.6% group) significantly increased the body weight with the best treatment of 0.1% experimental group. At day 15, astaxanthin markedly improved the body color. At day 30, the spirulina powder did not improve the body color. These results demonstrated that the spirulina powder may contribute to the early development of the juveniles but negatively affected the growth with the increase of feeding concentrations and the breeding time; however, and that 0.1% astaxanthin treatment was effectively enhance fish growth and body color development.

Abstract:Seven-band grouper (Epinephelus septemfasciatus) and Kelp bass (E.moara) grow fast and are considered to have great commercial potentials in marine fish cage culture in the temperate seas along the coast of Northeast Asia. There have been extensive aquacultural studies on these two species internationally in the past several decades. This study focused on the mass seed production technique of E.septemfasciatus and E.moara in China, which was newly developed in recent years. Recirculating aquaculture system (RAS) provides a stable environment for the fish growth that is not affected by natural conditions, hence has been the major breeding mode for a sustainable development in the aquaculture industry. In this mode one can easily compare the growth characteristics of different fish species. In this study we used curve estimation to analyze the model and to estimate the parameters for the growth of E.septemfasciatus and E.moara. Their growth was characterized based on the weights, the total lengths and the body lengths. After the 122-day culture, the average weights of E.septemfasciatus and E.moara increased from (114.836±25.343) g to (213.861±38.604) g and from (79.620±13.007) g to (238.086± 46.307) g respectively. The total lengths (TL) of E.septemfasciatus and E.moara could be described by functions TL=−0.006t3+1.622t+13.954 and TL=−0.013t2+2.008t+11.540 respectively, in which the variable t was the culture time. The relationship between the weight (W) and the body length (BL) of E.septemfasciatus and E.moara conformed to W=0.436BL2.055 and W=0.018BL3.083 respectively. The relative growth rates (RGR) were 0.707% for E.septemfasciatus and 1.631% for E.moara. E.septemfas-ciatus and E.moara did not show significant difference in the relative fatness (2.2−3.4, P>0.05).

Abstract:To explore the fertilization mechanism of Centropristis striata and improve the fertilization rate, the ultrastructure of spermatozoon and egg and the fertilization process were observed using the scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the sperm of C. striata was mainly composed of the following three parts: 1) head; mainly consisted with nucleus and without the acrosomal structure; 2) midpiece; consisted with mitochondrion, centriolar complex (including proximal centriole and matrix) and sleeve structure; and 3) tail; consisted with axoneme that is surrounded by plasma membrane. The axoneme of C. striata was consistent with the typical “9+2” structure in most fish. The eggs were spherical, colorless, and transparent with the diameter at (0.950±0.039) mm, which belonged to pelagic eggs. A big grain of oil ball (0.182 ± 0.011mm in diameter) was observed in the egg. Overlapping curves were observed on the surface of the eggs, on which the tiny holes with different sizes (0.246±0.103 µm) were evenly distributed. A completely-opened fertilization hole was in the central part of the funneled area at the animal pole. The shell of the egg included plasma membrane, vitelline membrane and shell membrane. The shell was filled with cytoplasm. The fertilization process of C. striata was short. The sperm penetrated into the egg through the micropyle in 10 seconds after insemination. The morphological feature of the fertilized egg changed after that, and the fertilization cone and fertilization plug were observed. Finally, about 60 s after insemination, the fertilization hole closed to prevent the penetration of other sperms. This study may provide theoretical foundation to improve the fertilization rate of C. striata artificial breeding.

Abstract:The current study described the morphological characteristics of the hybrid F1 by Epinephelus moara (♀) × E. septemfasciatus(♂) and the relationship to the offspring of its parents. The hybrid F1 of E. moara (♀) × E. septemfasciatus(♂) at 6 months old were measured and analyzed by the conventional morphometrics and the cluster analysis. Five traits of the countable characteristics and nine traits of the measurable characteristics of the hybrid F1 of E. moara (♀) × E.septemfasciatus(♂), E.moara, and E.septemfasciatus were analyzed. The result showed that the body shape of the hybrid F1 of E.moara (♀) × E.septemfasciatus(♂) were oval, flat and stout with seven taupe lateral bands on the side of body surface. The body color of the hybrid F1 by E.moara (♀) × E.septemfasciatus(♂) were a mixture of both E.moara and E.septemfasciatus. Among twelve measurable and countable traits for hybrid index analysis, there were six traits approached to E.moara, five traits approached to E. septemfasciatus and one trait approached to both the E.moara and E.septemfasciatus. The result of cluster analysis showed that the hybrid F1 of E.moara (♀) × E.septemfasciatus(♂) was closed to the female E.moara in the morphology. The study indicated that the body color of the hybrid F1 by E.moara (♀) × E.septemfasciatus(♂) appeared to be a mixture, and the morphological characteristics were closed to the female E. moara.

Abstract:Temperature plays an important role in fertilized egg hatching and the growth of larvae. The effects of temperature on marine fish at early developmental stages have been reported domestically and internationally. Temperatures above the optimal range may cause stress on the growth and increase the mortality rate and the deformity rate. However, the effects of temperature on embryonic development and the larval activity of F1 Epinephelus moara (♀)×E. septemfasciatus(♂) have been unknown. In this study we recorded the hatching rate, deformity rate and survival activity index (SAI) of the embryo and larvae of F1 E.moara (♀)×E.septemfasciatus(♂) at a series of temperatures (13℃, 15℃, 17℃, 19℃, 21℃, 23℃, 25℃, 27℃, 29℃, and 31℃), and identified the optimal temperature for the seed feeding. The good fertilized egg rate after 12 hours of hatching, the hatching rate and the deformity rate of newly-hatched larvae were also recorded. The SAI and survival rate of newly-hatched larvae were measured by not feeding the larvae till death. The results suggested that there was a positive correlation between the embryonic development of F1 and the temperature. The optimal temperature range for hatching was 17-25℃. When the temperature was above 25℃ or below 17℃, the hatching rate decreased and the deformity rate increased. The SAI of F1 first increased and then decreased along with the change in temperature. In the range of 17-21℃, the SAI showed higher values that were 32.14±2.83, 32.30±1.29, and 22.98±1.42 respectively. In conclusion temperature is a very important factor in the process of seed feeding. The optimal water temperature range may be between 17-21℃ for an improved germination rate and reduced mortality and deformity rates.

Abstract:The current study investigated the toxic effects of Cu2+, Zn2 , and Pb2 on the embryos and larvae of Epinephelus septemfasciatus. The results indicated that as the three heavy metals ion levels increased the fertilized egg hatching speed and the hatching rate gradually declined while the malformation rate gradually increased. The malformation of the embryos and larvae included bended tail sprouts, incomplete hatching, the “L”, “S” and “V”-shaped vertebrate of newly-hatched larvae and comma-shaped un-expanded tail deformity. Based on the comprehensive hatching rate, hatching rate and malformation rate, the toxicity to the embryonic development of these heavy metal ions were: Cu2 > Zn2 > Pb2 . The newly-hatched larvae toxicity test cycle was 96 h. The survival rate of the larvae gradually reduced with the increased time. The increased concentrations of these heavy metal ions dramatically decreased the survival rate while increased the number of deformity. Based on the time period of the half lethal concentration (LC50) and the safety concentration, the toxicity of three heavy metal ions on the newly-hatched larvae were: Cu2 > Pb2 > Zn2 . These results may contribute to the formulation of new fishery water quality standard and parameters of water environment monitoring and provide important scientific basis for E. septemfasciatus breeding of heavy metal monitoring and management.

Abstract:Disinfection of fertilized egg may prevent many pathogens and their vertical transmission; however, the toxic effects of disinfectants also exist. Therefore, it is important to control the type of disinfectants, their concentrations, and disinfection time. The current study investigated four commonly- used disinfectants on the hatching effects of Epinephelus fuscoguttatus(♀) × E. lanceolatus(♂) by bath method at (27±0.5)℃. Povidone-iodine, formaldehyde and chlorine dioxide treated for 10 min while Ozone treated for 1, 2 and 3 minutes respectively. The results indicated that the fertilized egg hatching and malformation rate were negatively associated with the concentrations of disinfectants and disinfection time. Formaldehyde and chlorine dioxide remarkably affected the hatching and malformation rate compared to those in the control group. Povidone-iodine had no effects on the hatching and malformation rate at 25 mg/L, 50 mg/L and 75 mg/L, but had significant effects at 100 mg/L. Ozone did not affect the hatching ability and malformations at 0.3 mg/L compared to the control group at all time points; and it had various influences at 0.5 mg/L, 0.7 mg/L and 1.0 mg/L of each time point. The hatching rate was extremely low (4.14%) and the deformity rate was 50.00% at 0.5 mg/L with 2-minute infection. These results suggest that the best condition for disinfection is as follows: povidone-iodine, 20–70 mg/L for 10 min; ozone, 0.3–0.5 mg/L for 1 min. Chlorine dioxide and formaldehyde are not recommended because of the side effects to the environment and humans.

Abstract:We applied experimental ecological approaches to study the allometric growth patterns at early developmental stages of Centropristis striata. Nikon E100 microscope and vernier caliper were used to measure the total length, mouth width, rostrum length, eye diameter, head length, head height, trunk length, trunk height, pectoral fin length and the tail fin length. All data were analyzed with appropriate statistical methods. The results showed that the growth of the total length of black sea bass conformed to the equation Y = 4.529-(9.227×10^-5)X³ + 0.015X² -0.189X (R²=0.994), and the dry body weight fit in the equation Y=0.002X³-0.151X² 3.257X-18.232 (R²=0.993)，which displayed a J-shaped curve. Most of functional organs showed allometric growth patterns. We found that organs responsible for feeding and locomotive functions had relatively early growth inflection points. The growth inflection points of the mouth width, rostrum length, eye diameter, pectoral fin length and tail fin length were 20, 44, 32, 36, and 19 days post hatching respectively. The growth inflection points of other organs appeared at later time: head length, head height, abdomen length and trunk height had inflection points on 56, 37, 44 and 60 days post hatching respectively. There were also other models of allometric growth patterns, for example, the head length showed a negative allometric growth before reaching the inflection point but a constant growth pattern afterward. Allometric growth patterns ensure the priority development of organs that are required in key functions such as feeding and escaping from predators, which improved the viability of black sea bass. Our study will greatly help establish appropriate breeding conditions for black sea bass.

Abstract:The current study investigated the Epinephelus fuscoguttatus(♀) × E. lanceolatus(♂) hybrid embryo and larvae in the terms of the morphological characteristics to provide a basis for the future breeding. The results show that embryonic development required 25 h 25 min at 27−28℃. The embryonic developmental process included five stages: cleavage stage, blastula stage, gastrula stage, nerve stage, and organogenesis stage. The post-embryonic development included larval, juvenile, and young fish stages at (27±0.5)℃, salinity 30, and pH 8 based on the features of the yolk sac, second dorsal fin spine, pelvic fin spine, scales, and body color. Larval was further divided into early and late larval larvae according to the presence or absence of yolk sac. Newly-hatched to 4-day was the early larvae, and larvae hatching yolk sac completely disappeared at 5 d. Fifty percent of larvae entered larval period at 32 d. Fifty percent larval completed the metamorphosis that developed into juvenile fish. The average total length of newly-hatched larvae was (1.65±0.11) mm, reaching (75.47±0.19) mm at 70 d. These results indicated that the hybrid offspring from conception to the later stages are healthy and normally-grown and developed; the disease-resistant heterosis had the appearance of “Epinephelus fuscoguttatus head and E. lanceolatus tail”.

Abstract:Artificial breeding of Chromileptes altivelis is difficult to marine fishing, and related studies on C. altivelis are limited. The present study investigated the embryonic and morphological development of larval, juvenile and young fish of C. altivelis using microscope, anatomical lens and digital camera. The morphological features and the time of development stages were described. The results showed that the embryonic development of C. altivelis was divided into five stages: cleavage stage, blastula stage, gastrula stage, neurula stage, and organogenesis stage. The embryonic development requires 27 h 25 min under the following condition in the sea water at 25−26℃ and salinity of 30. The post embryonic development of C. altivelis was divided into larval stage, juvenile stage and young fish stage based on the features of the yolk-sac, finfold, second dorsal fin spine, pelvic fin spine, scale, and body color. The larval stage was further classified into early larvae and late larvae based on the existence of the yolk-sac or not. The embryos developed into prelarvae in 2 days under water environment with temperature between 22 and 26℃, salinity between 29 and 31, DO≥5 mg/L. The yolk-sac of larvae disappeared and the postlarvae began at day 3. The larvae started to develop to juveniles at day 31. The juveniles completed metamorphosis and became young fish at day 57. The growth and configuration of the second spine of dorsal fin and the first spine of ventral fin were the most obvious changes during early development of C. altivelis. This study provides information for the propagation, seed culture and morphological identification of grouper fish.