Population biology of shrimp Macrobrachium jelskii (Miers, 1778) (Decapoda, Palaemonoidea) at the Grande River at northwest of the state of Minas Gerais, Brazil

Abstract

AIM: The population biology of the freshwater shrimp Macrobrachium jelskii was investigated here emphasizing the length-frequency distribution, sex ratio, reproductive period and juvenile recruitment. In addition, the abundance of individuals was correlated with the abiotic factors. METHODS: Samples were collected on a monthly basis from July 2005 to June 2007 along the river margin in shallow water of Grande River, at Planura region, State of Minas Gerais, Brazil (20º 09' S and 48º 40' W), using a trawl net (1.0 mm mesh size, and 2.0 m × 0.5 m wide). The fishing gear was handled by two people along the marginal vegetation of the Grande River in a course of 100 m, covered for one hour. In the laboratory, the specimens were identified, measured and sexed. RESULTS: A total of 2,789 specimens was analyzed, which corresponded to 1,126 males (549 juveniles and 577 adults) and 1,663 females (1,093 juveniles, 423 adults non-ovigerous and 147 ovigerous). The sex ratio differed significantly in favor of the females of M. jelskii (1:1.48; χ² = 103.95; p < 0.0001). The mean size of carapace length (CL) of females (6.32 ± 1.84 mm CL) was statistically higher than of males (5.50 ± 1.07 mm CL) (p < 0.001). The length-frequency distribution of the specimens revealed an unimodal pattern and non-normal distribution for males and females (W = 0.945; p < 0.01). No significant relationship between the abundance of M. jelskii and the environmental variables was observed (p = 0.799). CONCLUSION: The presence of ovigerous females and juveniles in the population suggests a continuous reproduction pattern and recruitment for M. jelskii at Planura region.

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

“…According to Bauer (2004), shrimp species distributed in clusters present a "pure search" mating behavior, in which there are neither agonistic interactions between males nor courting of females. In this type of behavior, the gametes are transferred to several females, which can explain the sex ratio skewed toward females in the population of this species, observed in this study and substantiated by Barros-Alves et al (2012). Another hypothesis for the sex ratio found for M. jelskii is possibly the different spatial distribution between sexes in large dammed water bodies.…”

“…Continuous reproduction is typical of M. jelskii (see Barros-Alves et al, 2012). This species exhibits lower average body size than M. brasiliense, so the difference in the condition factor of individuals with developed gonads is more representative, as evidenced by the significant variations in the monthly values throughout the year.…”

“…According to Barros-Alves et al (2012), M. jelskii exhibits a continuous breeding process, with females reaching larger sizes than males. In the Southeast and Midwest of Brazil, the reproductive period of M. brasiliense is restricted to the spring, with females smaller than males (Mantelatto and Barbosa, 2005;Pereira and Chacur, 2011).…”

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

“…In Brazil, studies on the reproductive biology of M. jelskii populations were carried out in the Southeast (Barros-Alves et al, 2012;Mossolin et al, 2013;Soares et al, 2015), North (Magalhães, 2000;Lima et al, 2013) and Northeast (Paiva and Barreto, 1960;Nery et al, 2015). However, no studies have investigated the biology of M. jelskii populations in the state of Bahia and in an urban artificial environment.…”

Biologia reprodutiva de Macrobrachium jelskii (Crustacea, Decapoda, Palaemonidae) no Rio São Francisco, Minas Gerais, Brasil

“…Barros-Alves et al (2012) no Rio Grande, noroeste do estado de Minas Gerais, Mossolin et al (2013) na região central de São Paulo e Paiva & Barreto (1960) no Ceará contribuíram com informações sobre a biologia, com ênfase nos aspectos reprodutivos, e Bastos & Paiva (1959), também no Ceará, estudaram sobre o consumo de oxigênio do camarão-sossego. No Amazonas, Magalhães (2000) verificou o desenvolvimento larval abreviado e, Gamba (1997) na Venezuela, obteve informações sobre a biologia reprodutiva da espécie.…”