Abstract:The resources status and species diversity of fish in Daiquyang were analyzed based on the data collected from the investigations from spring (May), summer (August) and autumn (November) in 2009 to winter (February) in 2010 by bottom trawl. There are three methods including sweep area method, biodiversity analysis and analysis of variance (ANOVA). The results showed that: A total of 38 species of fish were caught by bottom trawl, which belonged to 31 genera, of 21 families, 8 orders, 2 classes and 1 phylum. For percentage of number of species, biomass and number abundance density, warm temperature species all occupied the dominant position. Coilia mystus was the dominant species in all the seasons. On temporal distribution, both the biomass and the number abundance density in summer were the highest, but opposite in winter, and the biomas in summer was significantly different from that in winter (P<0.05), and same to the number abundance density (P<0.05). On spatial distribution, both the biomass and the number abundance density in northern area were higher than those in southern area, and those in the eastern were higher than those in the southern. By correlation test, the relationship between the biomass and average sea bottom water temperature can be denoted by binary curve (P<0.01). The Margalef richness index (D), Shannon-Wiener diversity index (H′) and Pielou evenness index (J′) in spring were significantly different from those in autumn (P<0.05). Compared with offshore water and deep sea in East China Sea, the Shannon-Wiener diversity index (H′) in Daiquyang was lower.

Abstract:Mud crab Scylla paramamosains is widely cultured in brackish and seawater ponds along the coast of southeast China including Shantou. In recent years, mud crab cultured in Niutianyang reclaiming coastal area of Shantou suffered from serious diseases, especially the bacterial diseases (such as Vibrio parahaemolyticus), which results in high mortality and great economic loss. In present study, V.parahaemolyticus isolated from Shantou Niutianyang crab culture area was injected to S.paramamosains to study the differential gene expression of the mud crab by cDNA-AFLP technology. Furthermore, 20 fragments that exhibited differential expression were discovered and sequenced. The results show that 6 fragments are homologous to the known functional genes, 5 of which are up-regulated. They are involved in energy metabolism including arginine kinase, phosphoenolpyruvate-carboxykinase and glyceraldehydes 3 phosphate dehydrogenase, arginyl-tRNA synthetase involved in transport progress, as well as the chymotrypsin-like proteinase involved in defense response. The other 8 fragments were identified to be unknown function genes. The result here shows that the response of S.paramamosain upon V. parahaemolyticus infection is involved in multiple pathways and needs further investigation.

Abstract:In this paper, 4 sections in Dongtou Archipelago were chosen to investigate the spatial-temporal distribution and the biodiversity of intertidal macrobenthos in autumn (Oct.) 2006 and spring (Apr.) 2007, respectively. The total number of macrobenthos in four sampling sites was 72, which included 44 species of mollusc, 13 species of crustacean, 11 species of macro algae, 2 species of polychetes, 1 species of echinoderm, and 1 species of the other group. Compared with the data in autumn and in spring, the number of species in the former (66 species) was slightly higher than that in latter (63 species), whereas the average biomass and abundance in the former (576.98 g/m²,461 ind/m²) were obviously lower than that in latter (1 129.23 g/m²,707 ind/m²). For all of the sections, Thais clavigera Kuster, Tetraclita japonica Pilsbry, Tectarius granularis Gray, were the dominant species and accounted for over 60% of the whole biomass and abundance. For the average index of biodiversity, the species biodiversity index was 1.73?0.47(0.83-2.10), the index of Margalef’s species richness was 2.26?0.33(1.99-2.95), the Pielou’s evenness was 0.62?0.19(0.29-0.85), and the index of Simpson’s dominance was 0.70?0.18(0.36-0.87). The whole result indicated human activities were the main factor to lead to the extremely unstable community in the intertidal macrobenthos with the lower biodiversity in Dongtou Archipelago. And there was a trend of evolving into the secondary type community structure.

Abstract:According to the 16S-23S rRNA gene sequences of Nocardia seriolae available in GenBank, a pair of primers was designed for establishing a SYBR Green I real-time fluorescence quantitative PCR method. It had a good linear relationship between initial templates and Ct values, and the correlation coefficient of the standard curve was 0.998. The sensitivity analysis showed that the developed SYBR GreenⅠreal-time PCR could detect 10^-6 μg/μL DNA. The specificity assay showed that negative control and the other bacteria such as Aeromonas hydrophila, Escherichia coil, Staphylococcus aureus, could not be detected by this PCR. Through the epidemic seasons, 16 fish tissue sample, 4 water samples and 8 fish bait tissue samples were detected by the real-time PCR assay. Results showed that 7 out of those samples were positive, which had good agreement (100%) with bacteriological analysis by isolation and culture. It was able to diagnose the clinically diseased fishes, and to recognize the carrier of N. seriolae as well. It reflected application value on early prevention and control of disease. The results showed that the developed SYBR GreenⅠreal-time PCR assay had the advantages of specificity, sensitivity, rapidity and quantitativity, and was able to be applied to the clinical diagnosis of N. seriolae in fish.

Abstract:There are scarce researches about the male reproductive system of Procambarus clarkii. This study aims to get some features of the male reproductive system of P.clarkii. The ultrastructure of the vas deferens was studied by using transmission electron microscopy, the microstructure of testis, vas deferens and spermatophore of P.clarkii was studied by using paraffin method, and the annual variation of the testis was investigated. Testis comprised many spermatogenic acini and collecting ducts whose structure is like grapes; The germ cells in the spermatogenic acini are transported to the vas deferens by through the collecting duct after matured; P.clarkii has a right and a left vas deferens, the right vas deferens was half longer than the left, the right vas deferens has a larger diameter, its curling degree and inclusion content are materially higher than the left, and secretory cells of the right vas deferens have more abundant endoplasmic reticulum. The vas deferens can divide into anterior, middle, posterior sections and a male gonopores acording to the difference of its morphous. Anterior and middle vas deferens can secrete materials for the formation of the spermatophore. The posterior section can store and ejaculate spermatophore. Male gonopores are the outcome of the vas deferens. The shape of spermatophore is elongated capsule or ellipsoidal. The spermatophore is composed of sperm mass, spermatophore matrix and two layers of spermatophore wall, sperm mass is in one side of the spermatophore. Male P.clarkii has two maturity periods that the most part of spermatogenic acini in the testis are at spermatid stage in its annual variation, and one is from May to August and the other is in October.

Abstract:For studying Elopichthys bambusa resource status in the middle and lower reaches of Pearl River, which could be used to guide fish resources protection and ecological restoration, larval Elopichthys bambusa were surveyed at Zhaoqing section in 2005 and 2006. Sampling was conducted continuously by Jiang net. The result show that reproduction period of E. bambusa lasted 105 days, and the larval was mainly occurred from May to July, accounted for 0.29% of the total fish larvae in 2006. The larval E. bambusa were 8.89?0.25 mm in total body length, and ranged from melanoid eye stage to yolk-exhausted stage. The density of E. bambusa and total fish larvae regularly changes with day and night. The density was higher at night than day time. Correlation and cross-covariance function analysis show that it was significantly correlated between density of E. bambusa larvae, discharge and water level in Guanliang hydrometric station (P<0.05, n=126), Luoding River was one of the main rivers that affected E. bambusa reproduction. It was also inferred that Luoding River and from Luoding River estuary to Wuzhou section were the main spawning grounds, which were contributing about 41.4% of the total E. bambusa larvae in the middle and lower reaches of Pearl River.

Abstract:The aim of this paper is to investigate the toxic influence of cadmium on the histopathological alterations of gill and hepatic cells in Tegillarca granosa exposed to various concentrations of cadmium(5 μg/L, 15 μg/L, 45 μg/L, 90 μg/L). The experiment lasted for 96 hours. The results are as follows: as the metal concentration rose, the gill cavity swelled, in which stored lots of haemocytes; finally the gill broke and dissolved, where the epithelia cells dropped; the findings of ultrastructure showed that there was granular osmiophilic material in gill epithelia cells, moreover, the number of secondary lysosome and mitochondrion increased, and the cells became vacuolated. The influnce of cadmium on the microstructure of hepatic cells was not obvious, only turning up some yellow sediment. However, its ultrastructure results indicated that the granular osmiophilic material was also present, and the secondary lysosome increased as well, consistent with the cases in gill; Furthermore, the nucleus of hepatic cells deformed and shrank, even showed vacuoles, suggesting the cells were irreversibly damaged. But the two most sensitive organelle, mitochondrion and endoplasmic reticulum, were normal, so we infer that the results may be caused by antioxidant enzymes, which were induced by cadmium.

Abstract:The study of fish behavior lays an important foundation for comprehending of fish migration routes, improving fishing efficiency and the protection of fishery resources. A large number of data are necessary in the study, such as stress response, cluster, migration and other measured data. However, getting these data is a time-consuming process. As fish behavior is often recorded in the form of video and a stereo camera recording system is popularly used for measurement and observation in the laboratory study, how to extract the data of fish behavior efficiently from the video has been a major problem in the study of fish behavior. By far fish 3D coordinate is usually calculated by hand, or by self made software which turns an importing fish 2D coordinate into a 3D one. In order to improve fish behavior data extraction efficiency, this paper presents an automated 3D fish tracking method based on a single video camera. A waterproof mirror was set above the experimental aquaria to simulate a camera shooting from the top, which provided a way to use a single camera for 3D imaging. We extract the data of fish behavior automatically by 3D fish tracking method which is divided into four parts: distortion calibration of single camera system, transfer formula between image coordinate to world coordinate, the automated tracking algorithm of fish movement and the automated output of fish behavior 2D and 3D data. Tests find out that while the distance between the camera and the aquaria is 1.5 m, the distortion calibration result shows the pixel error is much more acceptable which is about 0.1 pixels. As the camera tilted slightly during the experiment, the shape of the aquaria in the images changed. So based on the processing of Free-Form Deformation, the deformation of images is rectified during coordinate transform process. Then we implemented the algorithm of Interacting Multiple Model Joint Probabilistic Data Association (IMMJPDA) to automatically track fishes in 3D and output fish behavior data. The result of 6 Hemigrammus rhodostomus tracking experiment shows that: IMMJPDA algorithm can deal with the key issues during fish tracking system, which enables the method to extract individual fish from video images, construct their tracks, output 3D positions and speeds, and finally generate a complete 3D movement track drawing for fish behavior analysis. In a dense clutter situation JPDA requires a fairly large amount of computation to evaluate the joint probabilities. We combined Nearest Neighbor algorithm and JPDA algorithm to reduce the computational burden.

Abstract:This study was conducted to evaluate the effects of replacement of fish meal by housefly maggot meal (HMM) on growth performance, antioxidant and non-specific immune indexes of juvenile white shrimp (Litopenaeus vannamei). Six isonitrogenous and isoenergetic diets were formulated with 0, 20%, 40%, 60%, 80% and 100% replacement of fish meal with HMM on a protein basis. 960 juvenile shrimp with an average body weight of (0.56?0.03) g were randomly assigned to 6 groups. The shrimp were fed six diets respectively, named G0, G20, G40, G60, G80 and G100. After 45 d feeding, there was no significant difference in WGR (weight gain rate) from G20 to G60, while it was significantly decreased in G80 and G100. SGR (specific growth rate) of shrimp were significantly lower than that of the control group except for G40 (P<0.05). FI（feed intake）in G100 was significantly lower than other groups (P<0.05). Compared with the control group, there was no significant difference in FCR (feed conversion ratio), PER (protein efficiency ratio), PPV (productive protein value), HSI (hepotosomatic index) when the replacement levels were no more than 60%, while FCR, HSI were significantly increased and PER, PPV were significantly decreased with increasing HMM replacement ration. CF (condition factor) and SR (survival rate) in HMM groups were higher than those in the control group to some extent. With HMM increasing, crude protein, calcium and total phosphorus content increased significantly and crude lipid content decreased (P<0.05), while dry matter and ash content were not significantly different (P>0.05). No significant difference was found among all the treatments in serum and hepatopancreas SOD (superoxide dismutase) activity, and serum MDA (malondialdehyde) content (P>0.05), and MDA content in G80 and G100 was significantly higher than that of the control group (P<0.05). Serum PO (phenoloxidase) activity tended to increase first and then decrease, the highest value was observed in G20 (P<0.05). Hepatopancreas AKP (alkaline phosphatase) activity decreased significantly with HMM increasing (P<0.05). In all the treatments, no significant difference was observed in serum THC (total haemocyte count)，NO (nitric oxide ) content, AKP activity and hepatopancreas PO activity and NO content (P>0.05).

Abstract:In recent years, individual-based model (IBM) has been increasingly used to address issues in marine ecological environment because of its flexibility in incorporating different ecological processes. An IBM regards individual as a simulating unit, considering differences among individuals and influence of variability in spatial and temporal environmental conditions on individual development. This paper provides an overall review of scientific research in ecosystem-based fisheries management and resource recruitment forecasting. We introduced the basic concept, research methods and theory of IBM, and reviewed the status of research with the focus on the applications of larval transport, growth and mortality, prey-predation research using the IBM in fishery. Limitations associated with IBM approach are also discussed. We concluded that it is important for us to conduct interdisciplinary research between scientists in fisheries and other research areas to strengthen and improve our understanding of early life history dynamics for fish species in coastal waters of China, which is essential to develop an ecosystem-based management and assessment of fisheries resources.

Abstract:An important environmental concern associated with intensive fish culture is the production of ammonia, which is formed through ammonification of organic matter like unconsumed food and feces. The object of this study was to evaluate the effects of ammonia-N stress on the gill Na⁺/K⁺-ATPase, microstructure and serum physiological-biochemical indices of juvenile black carp, Mylopharyngodon piceus. The black carp, whose initial average weight was (7.00 ? 0.14) g, were transferred off the freshwater and exposed to different ammonia-N levels: 0 mg/L (low, control), 10 mg/L (middle) and 20 mg/L (high) NH₄Cl, each ammonia-N level was randomly triplicate and sampled at 0, 6, 12, 24, 48 and 96 h, respectively. The results indicated that the gill Na⁺/K⁺-ATPase activities in the middle and high ammonia-N treatment groups decreased gradually at first and reached the minimum at 12 h, 6 h, respectively, then increased gradually and reached the maximum at 48 h, and returned to the same level as that of control group after 96 h. Gill microstructure observation showed that chloride cell in middle ammonia group increased at 12 h; pavement cells fell off partly at 24 h; chloride cells vacuolated partly, blood capillary fractured and red blood cell overflowed at 96 h. But in high ammonia group, chloride cell increased at 6 h; pavement cells fell off partly at 12 h and largely at 24 h; After 96 h, blood capillary fractured on the base region of the lamellae and congestion, pillar cell disorganized of arrangement. Serum cortisol and glucose concentration in ammonia-N treatment group increased gradually at first 12 h, and then decreased gradually and returned to the same level as that of control group after 48 h. The activities of total superoxide dismutase (SOD) in ammonia-N treatment group increased significantly at first 6 h (P<0.05), and SOD activity in the middle ammonia-N treatment group returned to the same level as that of control group after 12 h, but SOD activity in the high ammonia-N treatment group was still significantly higher than that of control group after 96 h (P<0.05). Serum catalase activity decreased at first 6 h and then increased and reached the maximum at 12 h, and then decreased and recovered to the same level as that of control group after 48 h. Total antioxidant capacity (T-AOC), glutathione (GSH) and alanine transaminase (ALT) activities in am-monia-N treatment group decreased gradually at first 24 h, and malondialdehyde (MDA) concentration showed converse trends. After 96 h, GSH and ALT activities in ammonia-N treatment group returned to the same level as that of control group, however, the MDA concentration in ammonia group was significantly higher than that of control group and T-AOC activity in high ammonia group was significantly lower than that of control group. These results indicated that the ammonia stress could seriously disturb the antioxidant system at short-term ammonia-N stress, but fish showed the self-regulation ability , however, the antioxidant capacity decreased and gill structure was damaged after long-term ammonia-N stress.

Abstract:Mature Chinese mitten crabs, Eriocheir sinensis, are exposed to brackish water or coastal waters as an obligatory part during adult reproductive migration. In this study, we investigated the changes in serum total protein and oxyhemocyanin contents, alkaline phosphatase (AKP), superoxide dismutase (SOD) and phenoloxidase (PO) activities in both mature male and female E. when in freshwater and after step-wise acclimation to the following salinities: 7, 14, 21, 28, 35. Increasing salinities caused a gradual decrease in serum total protein and oxyhemocyanin contents. Serum AKP activity was elevated slightly at 7, thereafter it dropped slowly by the end of experiment. Serum SOD activity showed a slight decrease after increase of salinity until 21, it was activated above 21. Serum PO activity decreased gradually with the increase of salinity in males; however, it maintained a stable level above 21 in females. All tested parameters in serum except for SOD were significantly higher in females than those in males. It is suggested that elevated salinity induced a decrease in serum total protein and oxyhemocyanin contents. Serum immune enzyme activities in mature E. sinensis will be affected when the salinity was near to or above 28, which could exert a negative effect on reproduction. Further studies are needed to understand the biochemical adaptation of mature E. sinensis, during their reproductive migration acclimation to elevated salinities. Sex differences should not be ignored.

Abstract:In this study, the acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were extracted from scale of grass carp by the methods of acid and acid-pepsin. The partial biological properties of these collagens were researched and compared with pig skin collagen (PC). Experiment results indicate that the ASC, PSC and PC were type Ⅰcollagen and the triple helical structure in the three collagen samples. The thermal transition temperature of PC(41.6 ℃) was obviously higher than that of ASC(34.8 ℃) and PSC(35.2 ℃). The in vitro enzyme degradation properties of collagens were influenced by many factors, such as the enzyme variety, the isolation methods of collagen, the collagen sources, the thermal treatment and self-assembly degree of collagens. PSC can be degraded by collagenase, trypsin and papain, but the degradability of collagenase is the most notable. In the same conditions, the order of in vitro enzyme degradation ratio of these collagens were ASC>PSC>PC. The enzyme degradation ratio of these collagens could be increased after thermal treatment and could be decreased after self-assembly processing. The collagen sponges of ASC, PSC and PC have different structural and mechanical characterization. Sponges of ASC and PSC were porous and had low mechanical strength but the sponge of PC was the other way round.

Abstract:Allelopathic effects of Ulva prolifera on the harmful algae (Heterosigma akashiwo) were studied in laboratory. The results showed that the growth of H. akashiwo was significantly (P>0.05) lowered by fresh tissue of U. prolifera. The growth of H. akashiwo was not significantly (P>0.05) lowered by U. prolifera culture medium filtrate under initial filtrate addition, but the growth of H. akashiwo was strongly inhibited by macroalga culture medium filtrate under semi-continuous filtrate addition. The growth of H. akashiwo was strongly inhibited by dry powder and methanol extract of U. prolifera. The results showed that allelochemicals existed more in the tissue of U. prolifera than excreted to the medium and continuous addition of allelochemicals. It was important to effectively control the growth of H. akashiwo. The concentration effect of antagonistic relationship existed between U. prolifera and H. akashiwo.

Abstract:Wastewater treatment technologies with constructed wetlands and pond facilities for freshwater Litopenaeus vannamei culture were conducted and the effects were measured. The wetlands consist of free water surface (FWS) and subsurface horizontal flow (SF) wetlands. Ponds facilities contain aerators and artificial water purifying nets. During the middle and late culture period (about 60 d later), shrimp ponds’ wastewater was recirculated three times through the wetlands under hydraulic loading rate (HLR) of 1.65 m/d which effectively improved water quality in shrimp ponds and ensured a good harvest. At the same time, the outbreak of blue-green algae was controlled. -N and BOD5 at outlet were significantly removed at different levels (P<0.01 and P<0.05). The removal percentage and removal rates were 72.6%, 0.467 g/m²·d and 29.7%, 2.651 g/(m²·d). The removal percentage and removal rates of -P, TN and CODMn were 41.7%, 0.022 g/(m²·d), 26.1% , 2.619 g/(m²·d) and 15.9%, 3.738 g/(m²·d) respectively. The removal percentage of -N was only 3.6% but the removal rate was as high as 0.462 g/(m²·d). -N and -N were both significantly (P<0.01) reduced by 96.8% and 93.3% when effluents remained in the macrophytes unit for 4 d. The water chemical parameters were all maintained within a safe range during the culture period. The harvested shrimp in experimental pond had the mean body weight of 8.81 g and length of 9.36 cm. While the culture in control group had to terminate on the 60th day due to an outbreak of shrimp disease caused by microcystin and the harvested shrimp was only 3.06 g and 6.54 cm each. The results indicated that low frequency operation of the constructed wetlands under a higher HLR combined with pond facilities could effectively control water quality in shrimp pond under the conditions of no water exchange and no medicine use and then ensured a good harvest.

Abstract:Fish age and growth are key biological parameters for the assessment of fisheries resources. By the purse seiners and trawlers catch sampling, a total of 1 025 individuals of moonfish, Mene maculata were collected monthly in the mouth of the Beibu Gulf, South China Sea from August 2010 to May 2011. The samples ranged from 83 to 256 mm with fork length (FL). By biological measurement and age identification of 292 (female: 148, male: 144) pieces of vertebrae section, the age and growth of M. maculata were studied. Results showed that the annuli was composited of opaque wide band and transparent narrow band which indicated they were formed once a year, from August to October by monthly changes in the Marginal Growth Increment (MGI). Moreover, the Gonadosomatic index (GSI) designated that the time of reproduction period and formed annuli were similar. Both the GSI and the pelagic water temperature peaked from August to October, which indicated the close relationship of M. maculata spawned periods and pelagic water temperature. Age was determined by reading annuli on vertebrae, and the estimated age ranges from 0⁺ to 5⁺ years for female and from 0⁺ to 4⁺ years for male. The females and males moonfish showed similar ages structure and growth patterns, and the body weight and fork length data fitted the function W=6×10^-5L2.8415 (n=1025, r²=0.94, P>0.05). The fork length and age data fitted the von Bertalanffy growth function L_t=334.85[1-e^{-0.17(t+0.92)}]. It can be safely concluded that moonfish grows faster before age three, and then slows down.

Abstract:Aldolase is a glycolytic enzyme, which plays a key and pivotal role in glycolysis and glucose metabolism. And compared to aldolase A and aldolase C, aldolase B is involved in both glycolysis and gluconeogenesis. In this research, the two genomic sequence fragments are amplified according to two contigs cDNA fragments of ALDOB gene from EST database of grass carp(Ctenopharyngodon idellus). Then three nucleotides mutations were identified by using directly sequencing and blasting. The polymorphisms are C+687G, A117C and C+1042A, which are in exon 6, intron 7 and exon 8 respectively. C+687G is synonymous mutation and -A63C is non-synonymous mutation. 296 grass carps were used to genotype polymorphisms and then calculate the genotype and gene frequency by SnaPshot method. Frequencies of the AA genotype were 42.9%, 32.8% and 32.8% respectively, the AB genotype were 42.9%, 45.9% and 45.6% respectively, the BB genotype were 14.2%, 21.3% and 21.6% respectively. A general linear model was used to statistically analyze the relationship between ALDOB gene polymorphisms and major growth traits. The result indicated that the three different genotypes of C+687G site only showed significant association at body length/caudal peduncle ratio (P<0.05), while they showed no significant association at body weight. The three different genotypes of A117C andC+1042A sites showed significant association at body weight and so on (P<0.05). Three combinations of seven, three and seven diplotypes, with the minor allelic frequencies of above 3%, were constructed based on three SNPs in the experiment population. Association analysis indicated that three combinations of diplotypes were all significant association between diplotypes and body weight (P<0.05): the seven diplotypes of C+687G, A117C and C+687G, C+1042A showed significant association at body weight, body width and so on (P<0.05). And the three diplotypes of A117C and -43C, C+1042A showed significant association at body weight and space. Not only different genotypes of three SNPs sites, but also diplotypes showed significant association in major growth traits in grass carp. And the homozygous genotypes were higher than heterozygote genotypes in the main growth traits. As a result, ALDO B gene could be a candidate modifier gene for grass carp growth traits which could be useful for grass carp molecular breeding.

Abstract:Nemipterus bathybius is a small-size demersal species, which is mainly distributed in tropical and subtropical oceanic waters. The species is mostly in habitat offshore areas (>60 m) and caught commercially by hook-and-line and bottom trawl. The output of N. bathybius ranked first in the catch compositions of demersal fishes during bottom trawl survey conducted in 1964—1965. Recently, the stock density and yield of N. bathybius have changed dramatically, and the catches mainly consisted of young fish and the population structure was low-aged and miniaturization. Therefore, the aims of this research are to elucidate the effects of fishing activities and environment variations on its biological parameters, and provide theoretic basis for reasonable utilization and exploration.Based on the biological data obtained from bottom trawl conducted in the Beibu Gulf during 1992—1993 (1992), 1997—1999 (1997) and 2009—2010 (2009), population structure, growth and mortality parameters, as well as its annual variations of N. bathybius were analyzed. The results presented miniaturization and maturation at younger ages (and/or smaller sizes) of N. bathybius, as well as the growth rate increased and sexual maturity becameearlier. The average body length of N. bathybius lessened from 138.25 mm in 1992 to 112.70 mm in 1997, and 118.28 mm in 2009, respectively, the corresponding average body weight were 60.06 g, 39.03 g and 48.85 g. The parameters, asymptotic length (L_∞), growth coefficient (k) and zero-length age (t₀) in the von Bertanaffy growth equation in 1992, 1997 and 2009, were 242.2 mm, 0.39 and -0.39 a; 220.4 mm, 0.45 and -0.35 a; 235.5 mm, 0.48 and ?0.32 a, respectively. The inflexion age reduced from 2.19a in 1992 to 1.97a in 1997 and 1.86 a in 2009. Body length at 50% sexual maturity (L₅₀) diminished from 128.6 mm in 1992 to 116.5 mm in 1997, and 110.5 mm in 2009. The exploitation rates (E) in 1992, 1997 and 2009 were 0.57, 0.62 and 0.58, respectively. It suggested that the stock has been over-exploited since the 1990s. A series of changes of population parameters of N. bathybius in the Beibu Gulf indicated that in order to sustain their populations, N. bathybius has undergone adaptive changes under high fishing pressure.

Abstract:GIFT strain of Nile tilapia (Oreochromis niloticus) played an important role in world fishery. Several researches indicated that the growth performance of GIFT can still be improved. As an important indicator of breeding, body-weight was influenced by many morphological traits, and morphological traits that impact offspring body-weight might be changed after breeding, so comparative analyses of the impacts of morphological traits on body-weight between the offspring and parental generation became necessary. Sixty families of GIFT were introduced into FFRC as the parents (P) in 2006 for further study, three generations of offspring were bred (F1, F2, F3). In order to observe the achievement of breeding, body- weight (Y), body-length (X1), body-thickness (X2) and body-height (X3) of the P and F3 were measured, variation of four morphological traits of P and F3 were analyzed; correlation analysis, path analysis and regression analysis were used to calculate the correlation coefficient, path coefficient and the coefficient of determination, and the multiple regression equations between body-weight(Y) and morphological traits(X1, X2, X3)were established and analyzed. Results showed that: 1) compared with P, body-weight, body-length and body-thickness of F3 had a significant increase (P<0.01), meanwhile a certain decline in the coefficient of variation (CV) was observed, body size of tilapia of F3 showed a trend of being consistent. Male of F3 had increased in some degree, significant increase of 4 traits of the male group was not observed. 2) Trait affected the body-weight most of F3 converted to body-length, which was body-height×body-length in P. 3) The influence of body-length, body-thickness and body-height on body-weight declined more in F3 than that in P. Results above indicated that, breeding made a positive effect on the growth speed of GIFT; for further study we should be more careful in selecting morphological traits, and some other morphological traits which might impact the body-weight should be taken into account for more accurate breeding project.

Abstract:We documented the data of fish species systematically collected in Southwestern Continental Shelf of Nansha Islands according to Nelson"s classification system and analyzed the diversity at different taxonomic levels using inclusion index at taxonomic level (TINCLi), taxonomic diversity (△ and ∧ ), relative abundances (R) and the similarity index (C) at order and family levels. The results indicated that the fish species in the Southwestern Continental Shelf of Nansha Islands belonged to 20 orders, 110 families and 206 genera, and Perciformes is the major order. Analyzed by the inclusion index at taxonomic level, the average number of (families, genera, species), (genera, species) and (species) in per order, family and genus are (5.5, 10.30, 14.85), (1.87, 2.70) and (1.44), higher than the case of East China Sea Continent Shelf, Daya Bay and Dongsha Islands at order level. The values assumed the inverse proportion with the variation of latitude which demonstrated that the taxonomic diversity of fishes in lower-latitude was lower than the higher-latitude. The average taxonomic distinctness △ and the variation in taxonomic distinctness ∧ of the Daya Bay were tested in this paper by the PRIMER5.2. The average taxonomic distinctness △ was 65.8, and the variation in taxonomic distinctness ∧ was 110.0. Compared the △ with those of East China Sea continent shelf, Daya Bay and Dongsha Island, the genetic relationship of the composition of fish species in Southwestern Continental Shelf of Nansha Islands was closer than East China Sea continent shelf (65.7) and farther than Dongsha Island(55.2) and Daya Bay(62.2). Compared the similarity index, at the order and family levels, the composition of fish species in Southwestern Continental Shelf of Nansha Islands is similar to the Daya Bay.

Abstract:Somatostatin (SS) called also somatotropin release-inhibiting factor is a peptide named for its ability to inhibit pituitary growth hormone release. To facilitate investigation of the SS function in the teleost, its coding sequence in paralichthys olivaceus was isolated by the technique of Rapid Amplification of cDNA Ends (RACE). SYBR Green I Quantitative Real-time PCR analysis and immunohistochemistry were used to assess the expression of SS at mRNA and protein level. The deduced protein sequence contains 126 amino acid residues and a predicted molecular mass of 14.3 kD. Very low level of SS mRNA is presented during the first three days after hatching. The expression level of the SS gene was increased constantly before metamorphosis and steadily during the metamorphosis, then increased significantly during post-metamorphosis. There was no SS-positive reaction in the oropharyngeal cavity and esophagus. SS secreting cells are only distributed in the stomach, pancreas and pituitary. Several types of SS secreting cells could be distinguished in above organs. In stomach, SS secreting cells are dispersively distributed among the epithelium cells, presenting various kinds of forms such as ovoid, globular, triangle, elongated or spindle-shaped aspects. The pancreas and liver of flounder combine into a single organ named hepatopancreas, and SS-positive cells are only located in the pancreas, showing as globular-shaped, most of them are closed to blood vessels. SS-positive cells at high density are located in pars distalis of pituitary, so it is difficult to distinguish the shape of those cells.