The exploitation of bivalve molluscs in new fishing areas generally begins with scarce or no biological and fishery information to support management measures. The objective of this study was to estimate the morphometric relationships, growth parameters, and natural mortality in recently exploited populations of Megapitaria aurantiaca, Megapitaria squalida, and Dosinia ponderosa, to generate information on the population dynamics that could support management and conservation measures. The length–weight relationship and the relationships between the length, height, and width of the shells were calculated, which were used to estimate the morphometric size at first maturity. The parameters of the von Bertalanffy growth model were calculated through a modal progression analysis and the natural mortality was estimated depending on age. The morphometric relationships were allometric in all cases. The morphometric length at first maturity for M. aurantiaca is 67.60–77.20 mm, M. squalida is 35.40–40.32 mm, and D. ponderosa is 103.44 mm, which corresponds to ages between 0.68 and 5.97 y. The species exhibited a moderate growth (k = 0.421–0.448 y^-1). Natural mortality for the adult phase oscillated between 0.71 and 1.45 y^-1 and between 1.26 and 1.97 y^-1 during the juvenile phase. These estimates constitute basic inputs for fishery management and conservation of the species.