We analyzed the decline in the abalone harvest of two species Haliotis fulgens and H. corrugata, from one region composed of six study zones along the Baja California peninsula, Mexico. Survey data from 1991 to 2001 were used and density estimations with a Δ-distribution were computed. The results showed a dramatic decline in density (kg/10 m²) for both species. The decline in densities of H. fulgens and H. corrugata is consistent with a pattern observed since 1975. The current condition of the abalone stock is an example of an uncontrolled fishery. An increase in fishing effort or harvest rate must be avoided because we do not know the equilibrium density of these populations.