271 research outputs found

    Desova da pescada-foguete, Macrodon ancylodon

    Get PDF
    This paper aims at the determination of (1) period and area of spawning, (2) length and age at first spawning and (3) sex ratio of the 'pescada-foguete' (Macrodon ancylodon) from the southern coast of Brazil. The results obtained show that spawning occurs during October-May with a partial spawning in December and in March-April; the area of spawning was found to be between latitude 32ºS and longitude 51ºW and 52ºW. The first maturation occurs when the fish reach 25 cm long, being complete in about six months. The sex ratio found was 48% females for 52% males

    Mortalidade da pescada-foguete, Macrodon ancylodon

    Get PDF
    The instantaneous mortality coefficient (F + M) of the commercial weakfish, Macrodon ancylodon (Bloch, 1801) caught by trawls along southern Brazilian coast (from latitude 28ºS to 34ºS), was computed by means of the annual catch variation (in number) by age per fishing effort from March 1961 to December 1964. The instantaneous mortality coefficient mean values for female and male was respectivelly 1.31 and 1.53. One year old recruits appear in the landings and the mesh selectivity operates on fish up to three years old. Three-year old class predominates in the landings

    Crescimento da pescada-foguete (Macrodon ancylodon): aspecto quantitativo

    Get PDF
    We determined the age of the commercial marine fish "pescada-foguete" (Macrodon ancylodon, Bloch 1801) caught by trawls along the southern coast of Brazil (28ºS-34ºS), from 1961 to 1963, by means of the annuli in otoliths (CHUGUNOVA, 1959). We correlated the mean total length (L) in centimetres with the age (t) in years by means of the BERTALANFFY expression adjusted by FORD-WALFORD method (BEVERTON & HOLT, 1957). The mean total length was correlated with the mean weight (W) in grams, by means of the expression W = aLb adjusted by least square method, after a logarithmic transformation. Results

    Migração da pescada-foguete, Macrodon ancylodon

    Get PDF
    The "pescada-foguete" fish presented (1961-1964) migration along the southern coast of Brazil (from 28ºS to 34ºS), according to the following expression, adjusted by the least squares method: y = 30.2 + 1.7 cos 30 (x - 1.5) where: y - latitude with maximum production per unit effort (ºS) X = 1, % .... 12, months of the yea

    Análise da pesca da pescada-foguete na costa centro-sul do Brasil

    Get PDF
    In this paper data on catch and effort by gear are analysed, for weakfish (Macrodon ancylodon) landed at Santos from January 1959 to December 1963. The region studied was a narrow band about 30 nautical miles wide, along the southern coast of Brazil, between 23º S and 34º S. From the analysis of monthly data of production per unit-effort by squares of 1º on a side, we divided the studied region in two areas: area I (from 23º S to 27º S) and area II (from 28º S to 34º S). The index of unit-effort production and the effort concentration index were computed grouping the data by quarters. From the results we may drow the following conclusions: 1 - In a general way, the effort for catch weak-fish has been applied satisfactorily because the medium and large parejas have operated almost in areas with average density on¹ higher than average density; 2 - The production per unit-effort in the area I is smaller than the production in area II, which suggests that the index of abundance is higher in area II; 3 - The decrease in production per unit-effort, in area II, suggests a decrease in the abundance or availability of weak-fish in this area; 4 - In the area I, the index of production per unit-effort remained approximately at the same level

    Exotic radiation from a photonic crystal excited by an ultra-relativistic electron beam

    Get PDF
    We report the observation of an exotic radiation (unconventional Smith-Purcell radiation) from a one-dimensional photonic crystal. The physical origin of the exotic radiation is direct excitation of the photonic bands by an ultra-relativistic electron beam. The spectrum of the exotic radiation follows photonic bands of a certain parity, in striking contrast to the conventional Smith-Purcell radiation, which shows solely a linear dispersion. Key ingredients for the observation are the facts that the electron beam is in an ultra-relativistic region and that the photonic crystal is finite. The origin of the radiation was identified by comparison of experimental and theoretical results.Comment: 4 pages, 5 figure

    Additional records of metazoan parasites from Caribbean marine mammals, including genetically identified anisakid nematodes

    Get PDF
    Studies of marine mammal parasites in the Caribbean are scarce. An assessment for marine mammal endo- and ectoparasites from Puerto Rico and the Virgin Islands, but extending to other areas of the Caribbean, was conducted between 1989 and 1994. The present study complements the latter and enhances identification of anisakid nematodes using molecular markers. Parasites were collected from 59 carcasses of stranded cetaceans and manatees from 1994 to 2006, including Globicephala macrorhynchus, Kogia breviceps, Kogia sima, Lagenodelphis hosei, Mesoplodon densirostris, Peponocephala electra, Stenella longirostris, Steno bredanensis, Trichechus manatus. Tursiops truncatus, and Ziphius cavirostris. Sixteen species of endoparasitic helminthes were morphologically identified, including two species of acanthocephalans (Bolbosoma capitatum, Bolbosoma vasculosum), nine species of nematodes (Anisakis sp., Anisakis brevispiculata, Anisakis paggiae, Anisakis simplex, Anisakis typica, Anisakis ziphidarium, Crassicauda anthonyi, Heterocheilus tunicatus, Pseudoterranova ceticola), two species of cestodes (Monorygma grimaldi, Phyllobothrium delphini), and three species of trematodes (Chiorchis groschafti, Pulmonicola cochleotrema, Monoligerum blairi). The nematodes belonging to the genus Anisakis recovered in some stranded animals were genetically identified to species level based on their sequence analysis of mitochondrial DNA (629 bp of mtDNA cox 2). A total of five new host records and six new geographic records are presented.L'articolo è disponibile sul sito dell'editore http://www.springerlink.com

    Multifractal Scaling, Geometrical Diversity, and Hierarchical Structure in the Cool Interstellar Medium

    Get PDF
    Multifractal scaling (MFS) refers to structures that can be described as a collection of interwoven fractal subsets which exhibit power-law spatial scaling behavior with a range of scaling exponents (concentration, or singularity, strengths) and dimensions. The existence of MFS implies an underlying multiplicative (or hierarchical, or cascade) process. Panoramic column density images of several nearby star- forming cloud complexes, constructed from IRAS data and justified in an appendix, are shown to exhibit such multifractal scaling, which we interpret as indirect but quantitative evidence for nested hierarchical structure. The relation between the dimensions of the subsets and their concentration strengths (the "multifractal spectrum'') appears to satisfactorily order the observed regions in terms of the mixture of geometries present: strong point-like concentrations, line- like filaments or fronts, and space-filling diffuse structures. This multifractal spectrum is a global property of the regions studied, and does not rely on any operational definition of "clouds.'' The range of forms of the multifractal spectrum among the regions studied implies that the column density structures do not form a universality class, in contrast to indications for velocity and passive scalar fields in incompressible turbulence, providing another indication that the physics of highly compressible interstellar gas dynamics differs fundamentally from incompressible turbulence. (Abstract truncated)Comment: 27 pages, (LaTeX), 13 figures, 1 table, submitted to Astrophysical Journa
    corecore