Reproductive biology of<i> Macrobrachium amazonicu</i>m (Heller, 1862) (Crustacea: Decapoda, Palaemonidae) from the mouth and lower Amazon River regions, Brazil

Reproductive biology studies are crucial for understanding ecological and behavioral processes and establishing pillars for the sustainable exploitation of species of economic interest. Our study encompasses the general aspects of Macrobachium amazonicum reproductive biology in two important artisanal fishing areas: the mouth and lower sections of the Amazon River, located in the Brazilian states of Amapá and Pará, respectively. We captured 6,796 prawns, 4,163 females and 2,633 males, using 20 artisanal traps known locally as matapi. Our results showed that the reproductive peaks in both areas coincide with the rainy season in the Amazon (November 2017 to April 2018). Recruitment peaks were observed in July, both in the mouth and the lower Amazon regions. The average standard length of the females captured in the Amazon mouth was 56.85 ± 11.34 mm and 43.57 ± 10.48 mm in the lower Amazon section. There was a positive correlation between fecundity and female size in the regions. The average egg production was 3.026 ± 1.169 at the mouth and 1.346 ± 434 in the lower section. The reproductive investment average of the species was 11.05% (± 1.66) at the mouth and 12.67% (± 2.55) in the lower region. The mouth and lower Amazon River regions are favorable areas for the reproduction of M. amazonicum, as they attract females of all sizes.