Diferencias en la distribución de merluza (Merluccius hubbsi Marini, 1933) entre otoño y primavera en la Zona Común de Pesca Argentino-Uruguaya. Período 1998-2012

The variations in the spatial distribution of Argentine hake in Autumn and Spring in the Argentine-Uruguayan Common Fishing Zone were analyzed and related to the respective oceanographic conditions. The Principal Component Analysis was applied and fitting of General Linear Models to the spatial distribution of individuals for both periods in the northern area comprised between 35° S and 37° S performed. Juveniles aggregated, mainly, north of 37° S that coincided, in both seasons, with the area of the sharpest thermohaline gradient and highest spatial variation in temperature as well as salinity. In Autumn a significant relation between fish density and depth was verified. The concentration of individuals, that increased towards greater depths, was evident from 100 m at a temperature between 6-10 °C and 33.7-34.1 salinity. In the northern end of the region the presence of waters of subtropical origin was observed. In Spring, the species distribution  extended to the 50 m isobath that, at that depth, coincided with the location of the 10 °C isotherm. Unlike what was observed in Autumn, at that time of the year waters of subtropical origin were not detected, the relation between density and depth was not significant and bottom temperature decreased. To determine the resource distribution patterns in both seasons and deepen knowledge of the underlying causes would make a valuable contribution when establishing juveniles closed areas in the region.