HERNÁNDEZ, D.R., BEZZI, S.I. & IBAÑEZ, P.M. 2003. Análisis y diagnóstico del diseño de muestreo de las campañas de evaluación de merluza (Merluccius hubbsi), al norte y al sur de los 41° S (Zona Común de Pesca Argentino-Uruguaya y Mar Argentino). Años 1996-1999. INIDEP Informe Técnico, 52: 10 p. – Ver texto completo

Analysis and diagnosis of the hake (Merluccius hubbsi) assessment survey design, north and south of 41° S (Argentine-Uruguayan Common Fishing Zone and Argentine Sea). Years 1996-1999. Gain contribution by stratification in hake biomass estimation with respect to a simple random sampling based on the same sample size is analyzed. Considering as objective hake biomass assessment, curves which relate precision reached in estimations to the sample size are established. Data proceed from total hake biomass surveys carried out from 1996 through 1999; hake management units distributed north and south of 41º S are analyzed separately. Stratification used at present allows to obtain very variable gains in precision associated to biomass appraiser in the north management unit, with a maximun of 88% in 1996 and no gain in 1997. The south management unit presents also variable results but always with important gains. The applied sampling effort levels allow to obtain biomass estimation relative errors no higher than 29% in the assessment corresponding to the north management unit and 14% in the assessment relative to the south management unit. These values may be considered as very satisfactory. In the event of further diminishing estimation errors to obtain minimum gains it will be necessary to increase the sampling effort to levels which are inadmissible from a practical point of view. It does not seem feasible to diminish the present error of biomass estimation in both management units.