- ItemEvolución reciente de la captura por unidad de esfuerzo (1993-2004) y de las tallas medias (1993-2005) del pez palo (Percophis brasiliensis) en el litoral marítimo entre 34º S y 42º S(Mar del Plata: Instituto Nacional de Investigación y Desarrollo Pesquero, 2009) Rico, M.R.; Perrotta, R.G.Brazilian flathead (Percophis brasiliensis), of wide latitudinal distribution (23° S-47° S), is caught in Argentina in two coastal areas north and south of the Province of Buenos Aires delimited by the 39° S latitude. The species shows the highest abundance and catch yield percentages ( 5. ) of all coastal fish groups. The importance of the species makes it necessary to analyze mean lengths and define an annual abundance index that would allow to diagnose the state of the stock. To calculate the index the General Linear Model was adjusted. The factors used were Year, Quarter and 4 sub-areas, all statistically significant. The problem generated by the presence in the model of first order interactions that include the Year factor is discussed. It is concluded that the catch per unit of effort series did not represent changes in the resource abundance. Results suggest that caution should be taken when using the values normally considered to diagnose the state of the stock and implement management measures. Based on catch and effort values, the most important sub-areas were the mouth of the Río de la Plata river (1) and the Mar del Plata adjacent areas (3). A decreasing trend of the mean length throughout the study period was also observed.