Browsing by Author "Simonazzi, M."

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    Estructura por edad y sexo de la población de merluza
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Renzi, M.A.; Santos, B.A.; Simonazzi, M.
    Hake Merluccius hubbsi population structure in 1993, 1994, 1996, 1997 and 1998 and age and sex distribution during 1997 are analyzed. Data were obtained in research surveys. At the end of winter 1997 concentrations of juveniles were found in the San Jorge Gulf Argentine Sea, SW Atlantic, with maximum yields of 10,000 individuals per trawl hour for age 1 and 2,500 individuals per trawl hour for age 2. The highest concentrations of adults were found in the Gulf and South of 47°S, between the 100 and 200 m isobath, maximum yields of up to 1,700 individuals per trawl hour for age 3 and up to 90 individuals per trawl hour for age 7 and older. In spite of the decrease in population abundance, the basic age structure juveniles, young adults and old adults was stable in the period studied. Sex ratio of total population was approximately 1:1. Nevertheless, when sex and age proportion was estimated it was observed that, as of age 3, females were more abundant than males. The highest mortality rates for both sexes in the 1996-1997 period were observed in ages 3 and 4in 1997-1998 they corresponded to ages 6 and 7.
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    Pesca comercial y captura por unidad de esfuerzo de la merluza (Merluccius hubbsi) entre 34º S-41º S durante el período 1986-2005 y evidencias sobre cambios en la distribución y composición por tallas del recurso
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Irusta, G.; Castrucci, R.; Simonazzi, M.
    The activity of the hake (Merluccius hubbsi) commercial offshore ice chilling fleet and its relation to concentration, distribution and population areas of the stock distributed between 34ºS - 41ºS is described. The catch per unit of effort (CPUE) for the 1986-2005 period was estimated applying the General Linear Model. Data derived from the offshore fishing logs provided by the Argentine Secretary of Agriculture, Farming, Fishing and Food Administration and the information obtained in research cruises carried out in 1994, 1996-2001, 2003-2005 to evaluate the resource population abundance. During the main fishing time in the sector (quarter 2) and up until 1991 the fleet scattered within the Argentine-Uruguayan Common Fishing Zone (SW Atlantic). Later on the activity concentrated south of 39ºS where catches and the nominal effort reached their maximum value to decrease northerly as a result of the depletion of stock concentration and the development of the hake fishery in the Patagonian area. The zone south of 39º S is a sector of low concentrations where adult individuals prevail and a transfer zone of the fleet towards Patagonian fishing grounds (41ºS - 48ºS). The annual CPUE estimated with the General Linear Model decreased by 49% in the study period. As of 2000 the fishery became variable as regards catches, fishing effort and operation areas and more dependent on important recruitments as a consequence of the marked decrease of adults population abundance.
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    Relación largo-peso y largo-edad de primera madurez sexual de la merluza
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2003) Simonazzi, M.
    Estimations were made on the basis of a subsample of 6,734 individuals of Merluccius hubbsi from the Argentine Sea south of 41°S. Length-weight relation potential regression parameters were a=0.00950863, 0.01093448 and 0.01096117b=2.90831652, 2.86558431 and 2.86583191 for males, females and total individuals, respectively. The Newton algorithm was used to minimize the residuals. Maturity ogives were estimated with the logistic model adjusted by no lineal minimum quadratic ordinates. Length at first maturity at 50 was 33.79 cm for males and 35.38 cm for females. Age at first maturity estimated with the same model adjusted to the time elapsed from birth to catching was 2.61 and 2.67 years for males and females, respectively. Good fitting in all regressions was obtained.