Allozyme analysis was used to study the genetic variability of the <br /><br />bigeye croaker Micropogonias megalops in the Upper Gulf of California (UGC). <br /><br />Samples of 55 and 65 individuals were collected from commercial fishing zones <br /><br />in the UGC. Starch gel electrophoresis of proteins was used. Fourteen enzymatic <br /><br />systems were analyzed and 30 loci were detected. All polymorphic loci were<br />outside of the Hardy-Weinberg equilibrium and the inbreeding coefficient (Fis)<br />was 86%. Allozyme indicators were considered low for the population and indicate erosion in the genetic variability. Commercial fishing catch represents a population impact. A fishery management plan incorporated into the traditional economic activities is a proposal to assure this fishery resource.