Browsing by Author "Santos, B.A."

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    Crecimiento de la merluza (Merluccius hubbsi) del Atlántico sudoccidental entre 1993-2003 al norte y sur de 41º S
    (Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Renzi, M.A.; Santos, B.A.; Abachian, Viviana
    The reading of otoliths sagittae collected during the INIDEP (National Institute for Fisheries Research and Development, Argentina) assessment cruises carried out in the 1993-2003 period allowed to estimate length and weight growth parameters and the condition factor of hake (Merluccius hubbsi) and to prospect the two management units of the species north and south of 41ºS (Argentine Sea, SW Atlantic). A great variability in total length and weight in each age group was observed; nevertheless, stable mean length and weight values per age group were observed in the period analyzed. Besides, the values estimated to determine possible growth variations in each and between both management units north and south of 41ºS were compared. The comparison of growth curves of males and females in each area showed highly significant differences. When each sex between stocks was compared, some years those differences were observed for growth as a whole and only for some parameters in others.
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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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    Growth in the 0-group of Argentine hake (Merluccius hubbsi) from the Argentine-Uruguayan Common Fishing Zone
    (Mar del Plata : Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), 2006) Santos, B.A.; Renzi, M.A.
    Growth of hake (Merluccius hubbsi) in the 0-group from the Argentine-Uruguayan Common Fishing Zone was studied and spawning data were back-calculated by identifying daily growth rings in otoliths of specimens caught during research cruises performed in May 1997, May 1998 and June 1999. Total length (TL) range was 14-69 mm. Increments were read under microscope using an otolith daily ring measurement system (RATOC). Changes in the increment width data present a pattern that seemed to be similar, and independent from birth date of individuals. Data observed and back-calculated showed good accordance with the Laird-Gompertz model. Significant differences between coefficients were found in all comparisons of growth curves for observed and retrocalculated data. Growth rates estimated from observed data showed maximum values (ca. 0.54 mm d-1) at the stage of late larvae and minimum values at the stage of large early juveniles (ca. 0.25 mm d-1). For each year back-calculated hatching dates corresponded to the scarce mid-summer reproductive activity.