On the other hand postlarvae exploitation from the environment poses a additional pressure on the shrimp resource. One view is that the effect is negligible since larval mortality is naturally high. In order to assess the impact of larvae extraction on shrimp populations, Gracia (1989a,b) analyzed simulation models based on population parameters of white shrimp. The results showed that the impact of larvae extraction was variable depending on the stage of shrimp. There is a small impact when extraction takes place at the first stages and increases exponentially in later stages, mainly in juvenile stages. Natural mortality is a critical factor too. According to the analysis, postlarvae extraction has less effect when organisms are caught in the coastal zone close to the estuaries or coastal lagoons during shrimp immigration to nursery grounds.