Revista de Investigación y Desarrollo Pesquero 1984 Nro 4

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Browsing Revista de Investigación y Desarrollo Pesquero 1984 Nro 4 by Subject "Clupeiformes"

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    Características poblacionales de la anchoíta (Engraulis anchoita) del Mar Argentino. Parte I. El largo medio al primer año de vida, crecimiento y mortalidad
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1984) Hansen, J.E.; Cousseau, M.B.; Gru, D.L.
    A total of 7263 otoliths were collected from anchovy samples taken during two pelagic cruises which were carried out in the Spring of 1978. An statistical analysis of back calculated length distributions of one-year-old fish (L1) was made. The L1 mean values taken by geographical latitude form a cline, with higher values in the northern samples, and decreasing Southwards. Within this latitudinal gradient two main anchovy populations can be identified, one in the region of Buenos Aires Province and the other in Patagonian waters. The L1 of the females is significatively larger than that of the males for the former population, whereas in the Patagonian area differences between sexes are not significant. The parameters of the von Bertalanffy Growth curves, as well as the instantaneous total mortality rates (Z), were estimated for both populations by each cruise.
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    Estimación de la biomasa de adultos desovantes de la anchoíta (Engraulis anchoita) en el área costera bonaerense durante la primavera de 1981 y análisis comparativo de los recuentos de ictioplancton con redes de diferentes mallas
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 1984) Sánchez, R.P.; de Ciechomski, J.D.
    A bongo sampler fifted with nets of two different mesh sizes, 330 and 505 u. was used to collected 137 ichthyoplankton samples in the coastal areas off Buenos Aires Province in October, 1981. The efficiency of the two meshes for catching anchovy eggs and larvae and total ichthyoplankton was examined. The statistical analysis of the samples shows that there are no significant differences between the numbers of anchovy and total eggs collected by the different meshes. As regards anchovy and total larvae the finer mesh showed as significantly higher catching efficiency. The results of this partial estimate do not suggest that a major revision of the total assessment of the complete stock is necessary.