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1.
Abstract:   Age, growth and sexual maturity of the fan ray Platyrhina sinensis in Ariake Bay, Japan were determined from specimens collected from May 2002 to September 2006. Age determination was conducted by vertebral centrum analysis using soft X-radiography. Annual band pair deposition was determined by marginal increment and edge analyses. The von Bertalanffy growth model best described the overall pattern of growth for both males and females (males L ∝  = 455.2, k  = 0.56, t 0 = −1.09; females L ∝  = 555.8, k  = 0.28, t 0 = −1.77; L ∝ is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t 0 is the theoretical time at zero length). Parameter estimates suggest that females attain a larger asymptotic total length and grow more slowly than males. The observed maximum ages were 5 years for males and 12 years for females. Age at 50% sexual maturity was 2.1 years for males and 2.9 years for females. The results indicate that this species is relatively fast-growing, short-lived and early maturing compared with many batoid species.  相似文献   

2.
5种石斑鱼遗传差异的RAPD分析   总被引：3，自引：0，他引：3  
运用随机扩增多态性DNA（random amplified polymorphic DNA,RAPD）技术对鞍带石斑鱼（Epinephelus lanceolatus）、驼背鲈（Cromileptes altivelis）、棕点石斑鱼（E.fuscoguttatus）、斜带石斑鱼（E.coioides）和鲑点石斑鱼（E.fario）的遗传多样性及系统发生进行了研究。从120个RAPD随机引物中筛选出扩增效果好的引物19个,分别用于5种石斑鱼基因组DNA的扩增。结果显示,5种石斑鱼平均多态性位点比率（P）分别为64.23%,72.61%,60.34%,69.97%,73.94%;个体间平均遗传相似系数（S）分别为0.8238,0.8110,0.8345,0.8277,0.8064;平均遗传距离（D）分别为0.1762,0.1890,0.1655,0.1723,0.1936;平均Nei基因多样性指数（H）分别为0.1189,0.1364,0.1028,0.1439,0.1648;平均Shannon信息指数（Hi）分别为0.1801,0.1992,0.1530,0.2100,0.2434。5个种间的遗传距离（Dxy）在0.3964～0.6085之间。  相似文献   

3.
Abstract –  Using geometric morphometric (GM) techniques, we quantified intra and interspecific variation in female body shape using five collections each of Etheostoma caeruleum Storer, Etheostoma nigrum Rafinesque, and Etheostoma stigmaeum (Jordan). Nested multivariate analysis of variance showed significant variation in body shape among populations (Wilks' Λ = 0.0687, F 144,7585.1 = 19.35, P  < 0.0001), as well as among species (Wilks' Λ = 8.7 × 10−6, F 24,2 = 28.18, P  = 0.0348). Etheostoma caeruleum displayed greater body depth relative to both E. nigrum and E. stigmaeum , whereas E. nigrum displayed a compressed arrangement of mid-body landmarks relative to both E. stigmaeum and E. caeruleum . The broader implications of these findings highlight the value of geometric morphometrics as both an exploratory and analytical approach. Conclusions drawn from comparisons among moderately differentiated darter species in future studies of body size and shape are likely robust to intraspecific variation within species, and will permit more rigorous investigations into the ecomorphology of these benthic stream fishes.  相似文献   

4.
Donhyug  KANG  Kazuhiro  SADAYASU  Tohru  MUKAI  Kohji  IIDA  Doojin  HWANG  Kouichi  SAWADA  Kazushi  MIYASHITA 《Fisheries Science》2004,70(5):819-828
ABSTRACT:   Black porgy are hatched and released in marine ranching areas in Japan, Korea and Taiwan to maintain fisheries resources in coastal areas. If acoustic methods are used for field surveys, target strength ( TS ) information on the species is needed to convert acoustic data to biomass density. Target strength of black porgy ( Acanthopagrus schlegeli ) 15.5–32.9 cm fork length (nine individuals) was measured at 38 and 120 kHz (split beam) by ex situ measurements (cage and fishhook methods) of living fish, a tethered method with shock-frozen fish, and an acoustic scattering model, the Kirchhoff ray mode (KRM) model based on fish morphology. The ex situ TS -to-fork length ( FL , cm) relationships were TS 38kHz = 20log10 FL  − 64.6 ( r  = 0.77) and TS 120kHz = 20log10 FL  − 65.2 ( r  = 0.70). The values for the KRM model were TS 38kHz = 20log10 FL  − 64.8 ( r  = 0.88) and TS 120kHz = 20log10 FL  − 65.4 ( r  = 0.80). The agreement between the ex situ measurements and the KRM model for the mean TS was very good. In contrast, the results for the tethered method ( TS 38kHz = 20log10 FL  − 69.3 [ r  = 0.42]) differed markedly from the other two methods, perhaps because of the effects of the shock-freezing procedure in air. The results of the ex situ measurements and scattering model provide basic information for studying TS and conducting acoustic surveys of black porgy, even though the tethered method must be modified.  相似文献   

5.
两种杂交石斑鱼子一代杂种优势的微卫星标记分析   总被引：5，自引：3，他引：2  
使用6对微卫星引物对两种杂交子一代(青龙斑和虎龙斑)及其亲本(斜带石斑鱼、棕点石斑鱼和鞍带石斑鱼)共5个群体进行微卫星分析,计算等位基因频率、有效等位基因数、基因杂合度、多态信息含量、相似指数和Nei氏遗传距离。结果显示,在5种石斑鱼中,棕点石斑鱼的平均有效等位基因数最大(6.849 3),最小的是鞍带石斑鱼(2.608 6)。6对微卫星引物在这5个群体中具有丰富的多态性,平均多态信息含量(PIC)分别为0.666 7、0.751 3、0.441 9、0.664 0、0.542 6。在平均观测杂合度(Ho)中,虎龙斑和青龙斑的最高均为0.940 0,鞍带石斑鱼的最低为0.508 3。遗传距离和遗传相似率结果显示,青龙斑和虎龙斑均与父本鞍带石斑鱼的亲缘关系较近。杂交子一代群体的等位基因基本来自父母本群体双方,可推断杂交子一代的遗传物质来自父母双方,属两性融合生殖,是真正意义上的杂交种。杂交后代的遗传变异水平明显增强,这是杂种优势得以形成的重要遗传物质基础。  相似文献   

6.
ABSTRACT:   Elongate ilisha Ilisha elongata is a commercially important fishery resource in both Japan and China. Age and growth of the species were investigated by scale analysis from June 1996 to July 1997 in Ariake Sound, Japan. Scale annuli were formed once a year mainly between June and July. The age was 1–6 years for both male and female individuals. There was no significant difference in the regression of fork length (FL) on scale radius ( R ) between sexes by a covariance analysis. The combined sex von Bertalanffy growth equations were expressed as L t  = 495.4 × (1 − e−0.3176( t  + 0.4108)), where L t is FL in mm at age t . Comparison of the age and growth among different populations from coastal waters in the western North Pacific Ocean suggested that the FL of the Ariake population is the smallest at each age. The spatio–temporal variations in growth are possibly relevant to environmental conditions of the growth grounds of subadults; however, there was no gradient change in the growth of I. elongata with latitude. Water temperature may not be the main factor affecting the growth of this species . The growth of the tropical population from Sarawak differs greatly from those of temperate and subtemperate populations, which implies genetic variation or phenotypic plasticity in different climate zones.  相似文献   

7.
Length composition data from quarterly catches of Omani narrowband Spanish mackerel, Scomberomorus commerson (Lacepède), landed between 1987 and 1995 were used to estimate the growth, mortality and exploitation parameters of the stock. Non-linear least square fitting provided a complete set of von Bertalanffy growth estimates: L ∞ = 173.6 cm fork length; K  = 0.28; and t 0 = −0.86 years. There were no seasonal differences among the growth estimates. The instantaneous natural mortalities determined by three independent methods based on life-history parameters were 0.35, 0.64 and 0.77. Seasonal total mortalities were calculated by the length converted catch curve method for evaluating seasonal exploitation ratios ( E ). The E -values exceeded 0.4, indicating overexploitation during almost all the seasons studied. This was supported by the large reduction in the total landings of S . commerson from 27 762 t in 1988 to 3265 t in 1993.  相似文献   

8.
ABSTRACT:   A field experiment was conducted in the Matsumae area of Hokkaido, Japan, during June and July 2002, to investigate the effects of different entrance designs on the catch efficiency of fish traps by fishing with commercial traps (entrance inclination angle [α] = 37°; funnel length of entrance [ L f ] = 22 cm) and experimental traps. The experimental traps were of the same size and similar design as commercial traps, with different entrance inclination angles (trap E1: α = 46°; E2: α = 27°; E3: α = 0°; all L f  = 22 cm) or funnel lengths (E4: α = 37°, L f  = 8 cm). In total, 2200 fish during 200 trap hauls were captured. The catch was significantly higher using both traps E2 and the commercial trap than with trap E3 ( P  < 0.05), and the catch of trap E2 was higher than that of the commercial trap. There were no significant differences in mean fish body length or the frequency distributions of body length among trap types (E1, E2, E3 and commercial). The funnel length of the entrance also affected the catch of traps. Trap E4 had significantly higher catches than the commercial trap ( P  = 0.04) when traps were deployed for a 1-day soak time. Fish body length frequency distributions did not differ between trap E4 and the commercial trap. The results showed that catch can be greatly affected by trap entrance designs.  相似文献   

9.
Abstract  Culture-based fish yield in non-perennial reservoirs of Sri Lanka was related to reservoir morphometry and stocking density. The reservoirs were stocked mainly with fingerlings of one Chinese and three Indian major carp species, common carp, Cyprinus carpio L., and the genetically improved farmed tilapia strain of Nile tilapia, Oreochromis niloticus (L.), at four pre-determined species combinations and a range of stocking densities [ SD (fingerlings ha−1)]. Twenty-three reservoirs were harvested successfully at the end of the culture period of 2002–2003. Basic limnological and morphometric parameters, including shoreline development ( D L ) and shoreline area ratio ( R LA ), were estimated for each of the 23 reservoirs. Bray–Curtis similarity and non-metric multidimensional scaling using mean values of limnological data revealed that reservoirs could be ordinated into two major clusters, one with intact sample distribution due to similar trophic characteristics and the other with scattered sample distribution. Reservoirs in the cluster with similar trophic characteristics showed significant correlation ( P  < 0.05) between R LA and total fish yield ( Y ). A multiple regression equation, Y  = −693 + 4810  R LA  + 0.484 SD , was generated to estimate fish harvest in relation to SD .  相似文献   

10.
ABSTRACT:   The age, growth and maturation of the redbelly tilapia Tilapia zillii introduced into the Haebaru Reservoir on Okinawa-jima Island were studied using 2197 specimens ranging from 7.3 to 168.0 mm standard length (SL). The spawning season was estimated to be from April to August, with a peak in April and May. The first maturation sizes of females and males were estimated to be 38.1 and 33.0 mm SL, respectively. The opaque zones in otoliths that form annually were found to correlate with the spawning season. Maximum ages of females and males were 7 and 6 years, respectively. The von Bertalanffy growth formulae were expressed as: L t  = 99{1 − exp[−0.67( t  + 0.09)]} for females and L t  = 155{1 − exp [−0.36( t  + 0.12)]} for males. Males grew to be larger than females from the first year onward. Populations of this species are characterized by early maturation life history parameters and are thought to adapt and become established quickly after being released into new water systems. Furthermore, extermination activity in winter is thought to be an effective strategy before the newly recruited fish begin breeding in the warmer months.  相似文献   

11.
ABSTRACT:   The genetic diversity of wild and hatchery-released Pacific herring Clupea pallasii collected from three brackish lakes and two bays in Honshu and Hokkaido, Japan was examined with five microsatellite loci. All loci showed high genetic variability with expected heterozygosities ranging from 0.815 to 0.945. Significant differences in genotypic and allelic distributions were detected among all locations except for between the two bays in Honshu Island. Pairwise population analysis based on the F ST values showed close genetic relationships among the locations in Hokkaido Island, and the hierarchical analyses of molecular variance showed significant genetic difference between the two islands. Those results suggest the existence of subpopulations due to natal homing. In addition, stocked fish showed as much genetic diversity as the wild fish. The pairwise population analyses also showed close relationships between the hatchery fish and the wild fish in respective stocking areas, showing that no effects of stocking programs on genetic diversity of wild populations were detected.  相似文献   

12.
Juveniles of orange-spotted grouper ( Epinephelus coioides ), a tropical serranid species, are heavily harvested for aquaculture seeds from nursing grounds in several Southeast Asian countries. Because juveniles of similar sizes are present in a nursery area throughout the year, we aimed to determine whether more than one genetically distinct population contributes to juvenile aggregations. We examined the temporal genetic heterogeneity of juvenile aggregations collected at four different times of the year at a nursery area in coastal waters of the Andaman Sea in Trang province, Thailand. Also, we examined the differences between these temporal samples and an outgroup collected from the Gulf of Thailand (Chantaburi). The genetic variation at six polymorphic microsatellite loci within each sample was moderate, with observed heterozygosities across all loci ranging from 0.551 to 0.629 and number of alleles per locus ranging from 7.0 to 8.33. Results indicated substantial genetic differences between the two geographically distant samples, Trang and Chantaburi (Fst=0.040–0.050, P <0.005), and between the July sample and the remaining samples from Trang (Fst=0.096–0.106, P <0.005). The observed temporal genetic heterogeneity of E. coioides juveniles may reflect high variability in the reproductive success of each spawning event and the existence of spatially isolated groups of spawners.  相似文献   

13.
Proximate composition of some north-eastern Pacific forage fish species   总被引：3，自引：0，他引：3  
To understand the relative dietary value of forage fish as prey in the Bering Sea and Gulf of Alaska, whole organisms of 13 species were analysed for proximate composition (protein, oil, ash and moisture content). Eulachon ( Thaleichthys pacificus ) were high in oil (total lipid) (16.8% to 21.4%) and low in moisture (64.6% to 70.8%). Oil in capelin ( Mallotus villosus ) ranged from 2.1% to 14.0%. Juveniles of walleye pollock ( Theragra chalcogramma ), Atka mackerel ( Pleurogrammus monopterygius ), Pacific herring ( Clupea pallasii ), and prowfish ( Zaprora silenus ) had low oil contents (< 1.8%) and high moisture contents (> 80.3%). Rankings of median proximate values illustrate the similarities. Surf smelt ( Hypomesus pretiosus ), rainbow smelt ( Osmerus mordax ), pricklebacks ( Lumpenus spp.), Atka mackerel, Pacific sand lance ( Ammodytes hexapterus ) and Pacific sandfish ( Trichodon trichodon ) ranked high in median protein content (> 15.4%). Median ash content for all species ranged from 0.6% to 3.3%. Total wet mass caloric content (kcal g–1) was calculated for the four main species and a linear model was developed for caloric content as a function of moisture. The linear models (caloric content = b0 + b1 × moisture) were Pacific sand lance and Pacific sandfish (b0 = 7.82, b1 = – 0.09); eulachon (b0 = 7.97, b1 = – 0.08); and capelin (b0 = 9.70, b1 = – 0.11).  相似文献   

14.
石斑鱼循环水养殖系统及水源热泵应用研究   总被引：1，自引：0，他引：1  
通过构建石斑鱼的循环水养殖系统及水源热泵加温系统,达到在北方大规模养殖石斑鱼的目的。养殖系统由养殖池、弧型筛、循环泵、蛋白分离器、浸没式生物滤池、脱气池、溶氧池、紫外线灭菌器、液氧站组成。采用养殖废水收集及过滤装置处理后的养殖废水作为水源热泵的水源,通过2个冬季的运行,其冬季制热的平均制热能效比(COP)为2.66。在系统中养殖的第1批青斑鱼11个月内由24.41 g生长到480.66 g,存活率超过97%。养殖的第2批青斑12个月内由23.36 g生长到400.46 g,存活率达到84.5%。养殖的珍珠龙胆石斑7个月内由48.46 g生长到511.36 g,存活率达到71.24%。养殖的东星斑12个月内由41.13 g生长到223.56 g,存活率达到65.52%。本系统可实现青斑、珍珠龙胆石斑、东星斑等品种的常年均衡生长,并可降低石斑鱼的养殖成本。  相似文献   

15.
ABSTRACT:   Genetic differentiation and relationships between Crassostrea plicatula and Crassostrea gigas populations from China were studied by means of the microsatellite technique. Seven loci were used to screen five populations each collected from C. plicatula and C. gigas . All loci showed high polymorphism for all populations, as observed in average number of alleles per locus (19.1–28.1), and average expected heterozygosity (0.891–0.954). Significant departures from Hardy–Weinberg equilibrium due to heterozygote deficiency were observed over most populations at each locus and were best explained by null alleles. F ST values showed significant genetic differentiation between C. plicatula and C. gigas populations. According to the neighbor-joining tree constructed on the basis of the genetic distance ( D A), the ten populations fell into two distinct groups ( C. plicatula and C. gigas groups), and the results of principal coordinate analysis and assignment tests also supported the neighbor-joining clustering. The outcomes presented here suggested that the microsatellite markers have great potential for differentiating C. plicatula from C. gigas populations. The information obtained in this study has important implications for the suitable management and conservation of these genetic resources in China.  相似文献   

16.
ABSTRACT:   Five loci ( Phz2 , Phz6 , Phz7 , Phz12 , and Phz14 ) of microsatellite DNA markers developed in a previous study for parentage assignment in the hatchery population generated by mating among 61 broodstock fish (35 females and 26 males) in a spawning tank, were selected. After natural spawning in the same tank, larvae collected at three different times were categorized into early phase (EP), middle phase (MP), and late phase (LP) groups. In the parental broodstock, the mean number of alleles per locus was 21.8 and expected heterozygosity ( H E ) was 0.813. In the progeny, the mean number of alleles per locus decreased to 11.6 (EP), 14.4 (MP), and 6.4 (LP) and H E to 0.796 (EP), 0.833 (MP), and 0.681 (LP). Parental assignment determined eight dams and six sires as major parents for the EP group. In the MP group, 13 dams and ten sires genetically contributed to spawning, but only three dams and two sires were involved in LP group progeny. In the hatchery population produced from a limited number of parental fish such as the LP group, genetic variability was apparently decreased.  相似文献   

17.
ABSTRACT: Characterization was investigated on the 38 kDa and 42 kDa chitinase (EC3.2.1.14) isozymes from the liver of Japanese common squid Todarodes pacificus . Optimum pH toward colloidal chitin was observed at pH 3.0 for the 38 kDa chitinase, and pH 3.0 and 9.0 for the 42 kDa chitinase. K m and k cat of the 38 kDa and 42 kDa chitinases toward a longer substrate, glycol chitin, were 0.071 mg/mL and 1.22/s, and 0.074 mg/mL and 0.196/s, respectively. Alternatively, strong substrate inhibition of both chitinases were observed toward a short substrate, N -acetylchitopentaose (GlcNAc5). Both chitinases decomposed not only chitin but also chitosan (D. A. 95%). The cleavage pattern and reaction rate were investigated using N -acetylchitooligosaccharides (GlcNAcn, n  = 2–6). Both chitinases hydrolyzed GlcNAcn ( n  = 4,5, and 6). The release of GlcNAc was not observed. The speed of the reaction was observed to be in the following order: GlcNAc4 > GlcNAc5 > GlcNAc6 for the 38 kDa chitinase, and GlcNAc6 > GlcNAc5 > GlcNAc4 for the 42 kDa chitinase. Both the chitinases released p -nitrophenol from p -nitrophenyl GlcNAcn ( n  = 2, 3, and 4). N-terminal amino acid sequences of the 38 kDa and 42 kDa chitinases were YLLSXYFTNWSQYRPGAGKYFPQNI and EYRKVXYYTNWSQYREVPAKFFPEN, respectively.  相似文献   

18.
ABSTRACT:   Age and growth of Sebastes vulpes collected from the coastal waters of western Hokkaido were studied. Observation of the otolith margin verified that annuli (outer margins of the opaque zone) were produced chiefly from July to August. This period was associated with parturition and the birth season. The maximum age estimated by the surface method was 12 years but the oldest fish was aged at 35 years by the cross-section method. The surface method was inadequate for aging of S. vulpes older than 6 years because of the underestimation of age. No significant difference was found in the parameters of the growth equations between both sexes. The von Bertalanffy growth curve combined for both sexes was as follows: SL t  = 358.6(1 − exp−0.156( t +0.820)), where SL t is standard length (mm) at age t (after parturition in years). It seems likely that S. vulpes grows slowly and lives longer than previously thought.  相似文献   

19.
Abstract –  Pseudoplatystoma corruscans is distributed widely in the La Plata Basin in Brazil, where it is a very important species because of its high commercial value and ecological role as a voracious predator. This species undertakes long migrations during the dry and rainy seasons to feed and reproduce, respectively. In this study, we analysed seven microsatellite loci to test the hypotheses of the existence of a single panmictic population of P. corruscans in the La Plata Basin. All microsatellites analysed were highly polymorphic with the number of alleles per locus ranging from seven (Pcor28) to 30 (Pcor10). Across all samples, 107 alleles were detected. Thirty alleles were private, i.e., found in only one sample. Highly significant genetic differentiation was observed among samples in three of the four analyses performed: F ST (from 0.03435 to 0.16349, P  < 0.05), Analysis of molecular variance (amova) F ST = 8.25% ( P  < 0.0001) and amova R ST = 9.72% ( P  < 0.0001). A microsatellite multilocus Bayesian assignment test with the programme structure confirmed the division of the fishes into six groups largely concurrent with main branches on a population neighbour-joining tree. The obtained results rejected the panmixia hypothesis. On the other hand, the documented long-distance movements of P. corruscans and the geographical scale of genetic differentiation found in this study indicate a strong tendency for fish of this species to utilise their natal nursery regions for reproduction, which represents the first demonstrated example of homing in a freshwater catfish in South America.  相似文献   

20.
ABSTRACT:   Horse mackerel and tilapia surimi were subjected to six different heat and pressure treatments in order to compare gelation characteristics of easy- and difficult-setting gels, that is, temperature dependence, by observing rheological properties and microscopic molecular mobility. The stress–relaxation and proton spin–spin relaxation time (1H T 2) of water were measured for all treated gels. Horse mackerel gel demonstrated higher elasticity, large distribution of the stress–relaxation process, and smaller water 1H T 2 than tilapia in both heat and pressure treatments. The water 1H T 2 was steeply increased in the pressure treatment at around 294 MPa for both fishes. In contrast, the 1H T 2 rarely changed in the heat treatment in spite of the considerable change in rheological properties. From the experimental results, it is considered that the gelation of horse mackerel (easy setting) surimi is induced by highly unfolding and re-aggregation of protein, which contributes to the formation of a strong network structure compared with tilapia in both heat and pressure treatments, and that pressure treatments hardly improve the gel strength of tilapia (difficult setting) surimi. The water 1H T 2 measurement was used effectively in order to study gelation characteristics of easy- and difficult-setting fish through observing its molecular dynamics.  相似文献   

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