From September of 2003 until February of 2004 were carried out monthly samplings in the Gulf of Montijo-Veraguas, Panama. In the swamp of Muzzle, Mouth of the Trinidad, Gulf of Montijo was evaluated, aspects biométricos (I weigh fresh, total and dry, condition index, yield, and proportion of sexes). The populational structure of animals was studied collected in marked quadrants of 9 m². During the six months of study in the community of The Huacas 1351 animals were measured to estimate the structure of the commercial sizes. The density average in the quadrants of the swamp of Muzzle was considered in 1.00 org. /m2. Inside the parameters biométricos the condition index and the yield presented maxima respectively 54.02 and 33.87% and minima of 31.37 and 20.50%. The opposing proportion of sexes was of 1.68, however, statistically there were not significant differences with prospective proportion 1:1.