Browsing by Author "Díaz de Astarloa, Juan Martín"

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    Clave de identificación de cápsulas de huevos de condrictios del Mar Argentino
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Mabragaña, Ezequiel; Figueroa, Daniel E.; Scenna, Lorena B.; Díaz de Astarloa, Juan Martín; Colonello, Jorge H.; Massa, Ana M.
    Twenty eight species of oviparous chondrichthyans were reported on the Argentine Continental Shelf (SW Atlantic). The egg cases laid on the sea bed provide useful information to identify species, eggs laying areas and seasons. Based on the analysis of 155 egg cases corresponding to 21 chondrichthyan species, an illustrated field guide for a correct identification is presented.
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    Distribución y abundancia de cápsulas de huevo y aspectos del desarrollo embrionario de las rayas Bathyraja brachyurops y Bathyraja macloviana en la plataforma bonaerense
    (Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Vazquez, Diego M.; Gabbanelli, Valeria; Díaz de Astarloa, Juan Martín; Mabragaña, Ezequiel
    In this work the distribution and abundance of egg cases of skates Bathyraja brachyurops and B. macloviana on the Buenos Aires continental shelf and the Mar del Plata submarine canyon are analyzed and stages of embryonic development described. Although distribution, similar for both species, was registered south of 37° S at 84-215 m depth, some cases of B. macloviana were found down to 1,395 m. The highest abundance of B. brachyurops was recorded between 97-145 m and 251 m and that of B. macloviana at 94-105 m. Results indicate similar oviposition areas that coincide with the Argentine break front and the Patagonian scallop banks. Cases with embryos in different stages of development were collected. The anatomical structures, similar for both species in the first stages, showed differences in spinulation and pigmentation in the final ones. In both species early stages of development were found between July and September. The different stages observed in B. brachyurops embryos in July suggest oviposition at different times of the year. Those of B. macloviana found in the same stage in different seasons and in different stages in the same season suggest a similar oviposition pattern.
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    Observaciones sobre el ciclo reproductivo del mero, Acanthistius brasilianus (Serranidae, Pisces)
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1987) Dell'Arciprete, O.P.; Christiansen, H.E.; Díaz de Astarloa, Juan Martín
    The present paper deals with the study of the reproductive cycle of the sea-bass (Acanthistius brasilianus). Its main objective is getting some advance in the inderstanding of the gonad cycle of the sea-bass and the comprehension of its mode of reproduction. The study is emphasized on tahe females because it is thought that they permit a better analysis in this first stage of the reseach work. Some basic aspects, such as the anatomical and the histological description of the gonadas, the study of ovocyte maturation phases and the development of ovary maturity scales were into account. The gonad cycle was analized throughout the year by means of different approaches; histological analysis of ovary preparation and by following the statistical structure of percentage frequencies of ovocyte diameters, and those of the ovary maturity stages, and gonad indexes. The different phases of regression of the post-ovulatory follicles are also considered. Finally, the length at first maturity was calculated; and the spawning mechanism of this species is described.