Browsing by Author "Pájaro, M."
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- ItemConsideraciones sobre la alimentación de la caballa con especial enfasis en la depredación de huevos y larvas de peces(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993) Pájaro, M.Adult and juvenile fish inter and intraspecific predation may be an important source on these first development stages. In this work, adult and juvenile mackerel samples from two areas of Buenos Aires province, one south of Cape San Antonio and the other near Mar del Plata city were analyzed. An important anchovy postlarvae ingestion in both regions considered was observed. A high number of mackerel eggs in the stomach contents from adults was identified. This evidence of cannibalistic behaviour in the argentine mackerel is the first of its kind made in this species and allows to suggest that embryo mortality due to cannibalism might constitute and important percentage of the total embryonic mortality.
- ItemDescripción macroscópica de los ovarios del abadejo manchado (Genypterus blacodes). Escala de maduración(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Machinandiarena, L.; Villarino, M.F.; Cordo, H.D.; Macchi, G.J.; Pájaro, M.The macroscopic ovaric stages of pink cuskeel (Genypterus blacodes) females from the Argentine Sea (SW Atlantic) are described. They were classified in five stages of development based on changes in the appearance and size of the ovary: juvenile (I), developing (II), spawning (III), spent (IV) and resting (V).
- ItemDistribución de huevos, larvas y prerreclutas de merluza (Merluccius hubbsi) en la Zona Común de Pesca Argentino-Uruguaya. Período 1999-2001(Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Machinandiarena, L.; Brown, D.R.; Ehrlich, M.D.; Pájaro, M.; Dorado, J.; Teso, V.Distribution and abundance of eggs, larvae and prerecruit stages of Merluccius hubbsi were evaluated to examine spawning, nursery and settlement areas in the Argentine-Uruguayan Common Fishing Zone during the 1999-2001 period. Larvae and prerecruit stages were more abundant at stations from 50 m to 100 m depth. The nursery area would extend from the 50 m isobath south of 37° S to the 200 m isobath northward where the shelf becomes narrower. In the whole sampling area small size prerecruits were caught; therefore, the whole zone should be considered as a potential settlement area.
- ItemFeatures of the reproductive biology of the southern blue whiting (Micromesistius australis).(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999) Macchi, G.J.; Pájaro, M.Different features of the reproductive biology of the southern blue whiting (Micromesistius australis) are analyzed. Samples were obtained from research cruises and from commercial catches carried out between March-November 1995, in waters near Malvinas Islands. Reproductive activity of M. australis was observed between the end of July and September, southwest of Malvinas Islands. Oocyte diameter distribution of gravid females and the histological observations show that this species is a batch spawner with determinate annual fecundity. Preliminary estimate of the potential annual fecundity was about 478,000 oocytes for a 51-cm mean total length. Size at first maturity for this species was about 31 cm total length.
- ItemFecundidad parcial y frecuencia reproductiva del efectivo patagónico de merluza (Merluccius hubbsi)(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Pájaro, M.; Macchi, G.J.; Ehrlich, M.D.Batch fecundity and spawning frequency of Argentine hake inhabiting Patagonian waters south of 41° S were estimated using monthly samples collected during the December 2000-March 2001 reproductive season and at the end of the March 2002 spawning period. Batch fecundity was fitted to a power function of total length and a linear function of ovary-free female weight with values ranging between 100,000 (32 cm total length) and 2,300,000 (87 cm total length) hydrated oocytes. Batch and relative fecundity showed variations during the spawning season with a marked decrease towards the end of the reproductive period (March). The spawning frequency, which ranged between 0.10 and 0.15, was estimated from the proportion of females with day-1 postovulatory follicles and was higher during the spawning peak (January-February). At these frequencies, a female hake would spawn, on average, 14 times between December and March. Both, batch fecundity and spawning frequency showed higher variability within the same reproductive season than between years
- ItemIchthyoplankton composition, distribution and abundance on the southern patagonian shelf and adjacent waters.(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1999) Ehrlich, M.D.; Sánchez, R.P.; de Ciechomski, J.D.; Machinandiarena, L.; Pájaro, M.This paper reviews the information on pelagic and demersal fish eggs and larvae, describing the distribution and seasonality of different species and their arrangement in icthyoplankton assemblages in the Southern patagonian waters. It also reports on 11 surveys conducted by INIDEP during 1992-1995. A total of 488 ichthyoplankton samples were analyzed. Fish eggs have been recognized in 47. of all ichthyoplankton samples. They belong to three species: Coelorhynchus fasciatus, Macrourus whitsoni and Micromesistius australis. Fish larvae of 23 species and 17 families have been identified in 96. of all samples analyzed. Spawning of most species begins in autumn, and progresses through winter, when the southern blue whiting and grenadier fish contribute to more than half of all eggs present in our samples. Nototheniid and myctophiid larvae were caught during all year long. Four larval groups were detected using cluster analysis: the first group, formed exclusively by nototheniids, which occupied a vast area on the continental shelf between 100 and 200 m depth, the second formed by Agonopsis chiloensis, Eleginops maclovinus, Macruronus magellanicus and Sprattus fuegensis in coastal waters, the third formed by myctophiids, Gymnoscopelus spp. and Micromesistius australis, inhabit the outer continental shelf and slope, and the fourth included Protomyctophum spp., Krefftichthys anderssoni and Bathylagus antarcticus, species typically found in Subantarctic waters of the Malvinas Current. Comparing the distribution of eggs and larvae of blue whiting from collections obtained during the 70's and 80's, with those of recent surveys, it is evident, that a significant contraction of the spawning grounds of the species has take place, particularly to the west of the archipelago.
- ItemPresencia de veneno paralizante de moluscos en higado de caballa de la región costera bonaerense(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 1993) Carreto, J.I.; Akselman, Rut; Cucchi Colleoni, A.D.; Carignan, M.O.; Pájaro, M.During november 1992 an intense bloom of the toxic dinoflagellate Alexandrium tamarense accurred in coastal waters from Mar del Plata, Argentina. Toxicity testing of Mytilus edulis populations of the region revealed high levels of paralytic shellfish poison. In order to study the possible PSP accumulation in mackerel (Scomber japonicus), mouse bioassay (AOAC) was performed in livers from individuals captured during December 1992. Liver extracts were lethal to mice; the sumptoms observed were typical of those caused by paralytic shellfish toxins. Although PSPS concentration is below the established limit for human consumption, it suggests that mackerel can accumulate PSP toxins from its food. On the basis of stomach content analysis of sampled mackerel and the related literature, the occurrence of possible toxins vector organisms is discussed.