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- ItemCaracterísticas limnológicas, ictiofauna y abundancia de Odontesthes bonariensis de 35 lagunas de la región pampeana (Argentina)(Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Mancini, Miguel; Grosman, Fabián; Sanzano, Pablo; Del Ponti, Omar; Salinas, VíctorIn the shallow lakes of the Pampean region (Argentina), that have different limnological characteristics and are the habitat of a wide variety of fish, silverside Odontesthes bonariensis shows the greatest sport and commercial interest. Although those water bodies were categorized as clear or turbid, their open or closed condition has received little attention. It has been suggested that the connection between those environments favours displacement of fish and colonization of new ecosystems. The objectives of this work were to evaluate certain limnological characteristics, the diversity of ichthyofauna, catch per unit effort in number (CPUEn) and biomass (CPUEb) of O. bonariensis in 35 Pampean shallow lakes and examine their degree of association and differences according to the condition of open or closed. Of the 22 fish species identified, O. bonariensis and Oligosarcus jenynsii were the most frequent with richness ranging 1-14 species. Water conductivity and the CPUEn and CPUEb of O. bonariensis showed wide variations. It was determined that the geographic location influences ichthyofauna composition. Up to 8,000 µS cm-1the open/closed condition has a greater effect on fish richness and diversity than water conductivity. In open shallow lakes, the conductivity was correlated with the CPUEn of O. bonariensis. Although they are inhabited by a larger diversity of species, O. bonariensis is the most frequent in both types of aquatic environments.
- ItemDesarrollo embrionario de Pagrus pagrus bajo distintas condiciones de salinidad y temperaturas de incubación(Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Berrueta, M. Mercedes; Suárez, Julieta; Aristizábal, Eddie O.Pagrus pagrus is a demersal species widely distributed in the Mediterranean and the eastern and western shores of the Atlantic Ocean. In Argentina it distributes naturally along the coast of the Buenos Aires Province between 10 and 50 m depth. The estimate of egg quality during the early stages of embryonic development is a useful predictive criterion to evaluate the potential of the species to produce juveniles. The aim of this study was to describe in detail the stages of embryonic development and larval hatching time under different conditions of salinity and temperature. The fertilized eggs obtained from natural spawning were incubated at 15, 30 and 40 salinity levels combined with 14 and 18 °C temperature. In the different experiments the embryonic stages were photomicrographed and structures described. Egg development was completed in all experiments made. At 18 °C the fully formed embryo hatched at 40 h postfertilization; at 14 °C hatching occurred 73 h after. The effect of salinity on embryonic development was reflected in an irregular growth of blastomeres during the cleavage stages at 15 and 40 salinity with a subsequent abnormal development of the caudal region in larvae incubated at said levels. Knowing the embryonic stages, sequence of segmentation, time of organ formation and duration of embryonic development until hatching is a basic requirement to evaluate the quality of egg batches devoted to mass larvae production.
- ItemDistribución 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, EzequielIn 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.
- ItemAnálisis de los desembarques declarados de condrictios a partir de la implementación de la veda en el área del Tratado del Río de la Plata y su Frente Marítimo (2006-2014)(Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Bernasconi, Juan F.; Monsalvo, Mariano; Prosdocimi, Laura; Martínez-Puljak, Gustavo; Navarro, GabrielaIn 2007 the Comisión Técnica Mixta del Frente Marítimo established a closed area to bottom trawl in fishing rectangle 3656 to protect chondrichthyan reproductive aggregations and juveniles. The aim of this work was to analyze the evolution of said measure, the skate and shark landings declared during the 2006-2014 period in said rectangle and the distribution of the fleet before and after implementation. In the period evaluated, the duration of the closed area it was extended from 59 to 151 days and a reduction of tonnes of skates and sharks declared in the Argentine Uruguayan Common Fishing Zone of rectangle 3656 and an increase in the participation of said species in landings of the area of provincial jurisdiction was observed. The same trend was proved in the fishing activity if compare the season 2006-2007 (without closed area) and the season 2012-2013 (with closed area). During the closed season a northeast displacement of activities, a high catch level and fishing operations in the adjacent rectangles were observed.
- ItemMorfometría y topología del cerebro del pez tetra cola roja, Aphyocharax anisitsi (Characiformes: Characidae)(Instituto Nacional de Investigación y Desarrollo Pesquero, 2016) Rincón, Laura; Cavallino, Luciano; Alonso, Felipe; Lo Nostro, Fabiana; Pandolfi, MatíasIn this work a histological description of the neuronal nuclei present in the different regions of bloodfin tetra fish Aphyocharax anisitsi brain is presented. In addition, its external morphology studied quantifying the length and area of the main lobes (olfactory bulbs, telencephalic hemisphere, optic lobes and cerebellum) is shown. An ANOVA was performed to determine any possible significant differences among said structures. Ten individuals were fixed in Bouin’s solution and brains dissected to describe the external anatomy and digital image capture. In order to study the internal topology brains were processed for a paraffin histological protocol with microtome sections and Nisslstain. Results indicated the presence of the typical lobes described for other teleost species. The morphometrical analysis showed the optic lobes of the largest area and length and the olfactory bulbs of the smallest size. Said results suggest a predominance of the visual system. The cerebellum presented a larger total length than the telencephalic hemispheres with no differences as regards the area. Concerning the internal topology, it was observed that nuclei were associated to the anterior, medium and posterior brain. The nuclei found in the different regions did not show differences with regard to those described for other members of the Ostariophysi Superorder such as the zebra fish (Danio rerio) or the cardinal tetra (Paracheirodon axelrodi).