Length-weight relationship and condition factor of Macrobrachium amazonicum (Heller, 1862) (Decapoda, Palaemonidae) from a reservoir in Bahia, Brazil

Abstract

Macrobrachium amazonicum (Heller, 1862) is a freshwater prawn occurring in rivers and reservoirs of Central and South America. Given its broad geographical distribution, the species shows great intraspecifi c morphological, reproductive, physiological and ecological plasticity. Furthermore, it also stands out for its economic importance, especially in the states of North (Pará and Amapá) and Northeast Brazil. Despite the wide geographic distribution and economic importance of M. amazonicum, the biology of this species is poorly known, particularly in Northeast Brazil. We analyzed the length-weight relationships and condition factor of males and females of M. amazonicum. Specimens were collected monthly from September 2008 to August 2009 at the Pedra do Cavalo Reservoir, city of Cabaceiras do Paraguaçu, State of Bahia. All specimens were sexed, measured and weighted. After that, lengthweight relationships and the allometric (K) and relative (K r) condition factors were calculated. Altogether 2,974 specimens were analyzed, 334 of which were males (11%) and 2,640 were females (89%). Females were larger and heavier than males. Males and females showed isometric and negative allometric growth, respectively. Monthly variations in the condition factor were similar for both sexes, and correlated strongly with rainfall regime and temperature in the region. Such variations are not correlated with the reproductive cycle of the species, but are probably correlated with food availability and somatic growth.

Population biology of Macrobrachium jelskii (Miers, 1877) (Decapoda, Palaemonidae) from an artificial pond in Bahia, Brazil

“…The predominance of females and the smaller size of males are strong indications that the mating system in this case is "pure search" (sensu Correa and Thiel, 2003). This reproductive pattern was also observed in populations of Macrobrachium amazonicum (Heller, 1862) that inhabit lentic environments (Pantaleão et al, 2012;Rocha et al, 2015).…”

“…By ruling out hermaphroditism, variations in the sex ratio of populations of Macrobrachium spp. might be explained by other factors, for instance: differences in migration rates, mortality, longevity and growth between the sexes (Wenner, 1972;Souza and Fontoura, 1996;Mantel and Dudgeon, 2005;Mattos and Oshiro, 2009), and different reproductive strategies (Mossolin and Bueno, 2002;Hayd and Anger, 2013;Rocha et al, 2015).…”

Population structure of Macrobrachium amazonicum (Heller, 1862) (Decapoda: Palaemonidae) in Miranda Hydroelectric Plant Reservoir, Araguari river, Minas Gerais, Brazil

“…In our study, the presence of males with different morphological characteristics was not detected, such as in other studies (Pantaleão et al, 2012;Hayd & Anger, 2013;Rocha et al, 2015) with females larger than males. The weak expression of this sexual dimorphism associated with the absence of investment in the defense of potential females for mating make the males smaller.…”

“…2017) with few studies in the northeast (Sampaio et al, 2007;Rocha et al, 2015) and southeast region (Pantaleão et al, 2012(Pantaleão et al, , 2014Silva et al, 2017).…”

Length/weight relationship and condition factor of Macrobrachium jelskii (Miers, 1877) and M. brasiliense (Heller, 1862) (Decapoda, Palaemonidae) in two locations in the state of São Paulo

“…In fish and crustaceans species, the adaptation to environments can be verified by the condition factor (Rocha et al, 2015). This value is obtained by the weight gain/length gain ratio, which indicates the general welfare of the animal (Rodrigues et al, 1988;Susanto and Irnawati, 2014).…”