Abundance and Morphometric Relationships of Amazon Shrimp - Macrobrachium amazonicum (Heller 1862) (Decapoda, Palaemonidae) - In an Amazon Estuary - North Coast of Brazil

Abstract

From Macrobrachium amazonicum ( Heller, 1862 ) (Decapoda, Palaemonidae) abundance in monthly collections in the Amazon estuary and on Mosqueiro Island (State of Para, Brazil) between April 2006 and August 2007, we verified that the site mentioned is favorable to the development of the species, since there is a significant number of young and adults specimens throughout the year, whose abundance is significantly higher in the dry season. Icoaraci was the site of great contribution in the total of specimens caught, relating this productivity to the large amount of organic matter in suspension. In this study, we found the largest M. amazonicum specimen ever collected, comparing to those mentioned by available scientific literature. The individual was a female caught on Combu Island with 44.72 mm carapace length or 18.45 cm total length. Relations of body mass (g) vs. carapace length (mm) for males, females and sexes together had negative allometry, which can be associated to the gonadal maturation cycle of the species. All other morphometric relationships showed positive allometry. Keywords . carapace; bio-ecology; population dynamics.