2003 - INIDEP Informe Técnico Nro 50-56

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Browsing 2003 - INIDEP Informe Técnico Nro 50-56 by Subject "Buenos Aires"

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    La caballa (Scomber japonicus) y las condiciones del ambiente en el área "El Rincón" (39°40'-41°30' S) del Mar Argentino. Septiembre, 2000
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Perrotta, Ricardo G.; Viñas, M.D.; Madirolas, Adrián O.; Reta, Raúl; Akselman, Rut; Castro Machado, Federico J.; Garciarena, A. David; Macchi, Gustavo J.; Moriondo Danovaro, Paula I.; Llanos, V.; Urteaga, J.R.
    Between September 1st and 6th a research cruise was carried out in the Buenos Aires shelf area of "El Rincon" 39°40'-41°30'S, Argentine Sea SW Atlantic. The total area studied was 2,527.8 nautical mile2. Knowledge of the commercial fleet location at the time of the survey allowed to intensify sampling in a 'miniarea' of 52,8 nautical mile2. The acoustic assessment of chub mackerel (Scomber japonicus) biomass was 49,511.9 t, 94 of which corresponded to this last area. Fish samples coming from fishing trawls included only adult individuals of 240-460 mm total length (TL) and ages ranging 2-11 years. The limit age was estimated at 13 years and natural and total mortality rates at 0.23 and 0.54, respectively. Oceanographic conditions were those typical of the winter season, characterized by the vertical homogeneity of the water column in temperature and salinity. The isotherms and isohalines distributed parallel to the 50 m isobath with values progressively decreasing from the coast towards the slope. Salinity values allowed to detect two hydrographic regimes: that of the San Matias Gulf 33.8-34.4 located to the West and covering more than half of the study area and the one of the Shelf Waters 33.5-33.79 occurring towards the East. A positive gradient in chlorophyll a concentration was observed in N-S sense and from the coast towards the shelf break. The highest densities of phytoplankton, with dominance of diatoms, were observed in the southern sector. Low concentrations of Alexandrium tamarense and Prorocentrum minimum, two potentially noxious dinoflagellates, were detected. The highest zooplankton biomass associated to the highest salinity values and salinity gradients, represented mostly by Calanoides cf. carinatus, was also detected in the southern sector. The western sector, influenced by the San Matias Gulf regime and characterized by high densities of both, phytoplankton and zooplankton, may constitute a potentially favourable feeding ground for chub mackerel.
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    Estudios químicos y bacteriológicos del río Baradero (Argentina): calidad sanitaria del agua y aptitud de los peces para consumo humano
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Costagliola, Marcela; Seigneur, G.N.; Jurquiza, Verónica
    As a result of an agreement signed by the Municipal Government of Baradero Buenos Aires Province, Argentina and the INIDEP, the sanitary quality of the Baradero River waters was studied and fish safety assessed. Results of five field surveys carried out between 1993 and 1997 are studied. Organochlorine and organophosphorate pesticide residues, as well as traces of heavy metals were analyzed in 49 fish specimens and aerobic heterotrophic bacteria (AHB), total coliform bacteria (TC) and fecal coliform bacteria (FC) were counted out in 7 sampling stations placed on the coast and the riverbed. Alpha Hexachlorohexane, gamma Hexachlorohexane, beta Hexachlorohexane, Aldrin, Heptachlor epoxide, pp'DDE and Dieldrin were detected in fish tissues. The values of AHB found in different stations were not statistically different. The FC density on the coast was significantly greater than that found in the riverbed. Enterobacter cloacae, Morganella morganii, Proteus mirabilis, Escherichia coli, Aeromonas hydrophila and Non-O1 Vibrio cholerae were identified. It is concluded that the current levels of heavy metals and pesticide residues in fish are not dangerous for the average consumer nevertheless, further research is needed to assess the risk for groups with higher consumption rates, such as sport and subsistence fishers. On the other hand, there is microbiological pollution in the river owed to both, industrial wastewater and sewage discharges. The recorded bacterial stocks, pathogenic or potentially pathogenic, are susceptible to cause illnesses.