Population studies about species in the Order Dictyotales have been concentrated in temperate areas (Allender 1977; Benson 1986; King and Farrant 1987; Malbran and Hoffman 1990) and some in tropical zones (Ganesan et al. 2000; Montanes et al. 2006; Paul-Chavez et al. 2006). Among the population parameters studied, seasonal changes in cover and size has been found (King and Farrant 1987; Paul-Chavez et al. 2006). However, mostly of the studies were done at the same depth or tide level, broader spatial comparisons are not common (Liddle 1975), specially in relation height/width of the thalli. Density has been used as a population descriptor in other genera (Montanes et al. 2006). In relation to reproduction there are contradictory information exist, because in some populations reproduction is continuous (King and Farrant 1987; Phillips 1988; Ganesan 2000) while in other populations reproduction is seasonal with peaks in autumn (Benson 1986) or winter (Malbran and Hoffman 1990). The only coincidence in all the studies is the dominance of tetrasporophyte thalli (Foster et al. 1972; Allender 1977; King and Farrant 1987; Montanes et al. 2006) and the regeneration from mitotic spores and fragments (Gaillard 1972; Foster et al. 1972; Benson 1986). Population studies of Dictyotales in Mexican Pacific have been done at the southern Gulf of California in where Paul-Chavez et al. (2006) developed a population study of P. caulescens Thivy, in where strong seasonal variations in biomass, size structure and reproduction were observed while cover remained constant suggesting as a good population parameter for comparisons. A second study in the same area by Altamirano-Cerecedo and Riosmena-Rodriguez (2007), evaluated the influence of geography in the morphology and reproductions of Dictyota crenulata J. Agardh. They found variations in size and proportion of reproductive life cycle stages in relation to the geography suggesting strong population changes. In the case of P. concrescens, Ortuno-Aguirre and Riosmena-Rodriguez (2007) described the dynamics of the epiphytes in relation to the host. However, studies in other species might let us understand better the population’s trends in the subtropical areas (like the Baja California Peninsula) with the hypothesis that permanent populations are present in those areas based on a Algae Volume 24(1): 31-38, 2009