From monthly zooplankton samples collected during October 1976 to October 1977, the seasonal variation of zooplankton standing crop and its relation to the number offish larvae from Bay of Concepción has been established. The zooplankton standing crop varied between 58 ml/m² in August and 430 ml/m² in January. The number offish larvae in the same sample ranged from 30 larvae /m² in January to 1045 larvae/m² in March. An inverse relationship between the zooplankton standing crop and the number of fish larvae it was checked and this relation is discussed according to the bibliographic antecedents.