ABSTRACT. The aim of the present study was to determine the size at sexual maturity in the freshwater crab Dilocarcinus pagei Stimpson, 1861, from a population located in Mendonça, state of São Paulo, Brazil. The crabs were sampled monthly (July 2005 to June 2007, at Barra Mansa reservoir. The specimens were captured manually or in sieves passed through the aquatic vegetation. The crabs were captured and separated by sex based on morphology of the pleon and on the number of pleopods. The following dimensions were measured: carapace width (CW); carapace length (CL); propodus length (PL); and abdomen width (AW). The morphological analysis of the gonads was used to identify and categorize individuals according to their stage of development. The morphological maturity was estimated based on the analysis of relative growth based on the allometric equation y = ax b . The gonadal maturity was based on the morphology of the gonads by the method CW 50 which indicates the size at which 50% of the individuals in the population showed gonads morphologically mature to reproduction. The biometric relationships that best demonstrated the different patterns of growth for the juvenile and adult stages were CW vs. PL for males and CW vs. AW for females (p<0.001). Based on these relationships, the estimated value to morphological sexual maturity was 21.5 mm (CW) in males and 19.7 mm (CW) in females. The determination of the size at sexual maturity and the adjustment of the data based on the logistic curve (CW 50 ) resulted in a size of 38.2 mm for males and 39.4 mm for females (CW). Based on the data obtained for sexual maturity for D. pagei, we can estimate a minimum size for capture of 40 mm (CW). This minimum size allows at least half of the population to reproduce and retains the juveniles and a portion of the adults in the population.KEYWORDS. Allometric growth, gonadal maturity, morphological maturity, reproduction. Os caranguejos foram separados por sexo, de acordo com a morfologia do abdome e pleópodos. As dimensões mensuradas foram: largura da carapaça (LC); comprimento da carapaça (CC); comprimento do própodo (CP) e largura do abdome (LA). Além disso, análise morfológica das gônadas foram realizadas e caracterizadas em relação ao estágio de desenvolvimento. A maturidade morfológica foi estimada com base no estudo do crescimento relativo, esta análise é baseada na equação alométrica y = ax b e a maturidade gonadal através da morfologia das gônadas, utilizando o método LC 50 indicando o tamanho em que 50% dos indivíduos encontram-se com gônadas desenvolvidas para a reprodução. As relações biométricas que melhor indicaram os diferentes padrões de crescimento das fases jovem e adulta foram LCxCP para os machos e LCxAB para fêmeas (p<0,001). Baseado nessas relações, o valor estimado para a maturidade sexual morfológica em machos foi de 21,5 mm (LC) e de 19,7 mm de (LC) para fêmeas. Na determinação da maturidade sexual gonadal, o ajuste da curva logística (LC 50 ) resultou em um tamanho de 38,2 mm para os machos e 39,4 mm para...

This study aimed to analyze the carcino-bycatch of seabob shrimp (Xiphopenaeus kroyeri) in Macaé/RJ, a region influenced by the Cabo Frio upwelling. Samples were collected monthly with a shrimp fishing boat, from July/2010 to June/2011. The carcino-group bycatch was represented by 15 families, 24 genera and 30 species. The families with the highest number of species were Portunidae (7) and Penaeidae (5), representing 23.33% and 16.66% of the total catch, respectively. For each seabob shrimp captured, 2.94 bycatch individuals were caught on average, with the largest discrepant values in summer (1: 4.82) and autumn (1: 5.76). The main components of this carcinofauna (Artemesia longinaris and Pleoticus muelleri) are species with increasing importance as a fishery resource in the region due to their abundance, and need to be continuously studied over diverse aspects of population biology, aiming to improve conservation actions.

The seabob shrimp Xiphopenaeus kroyeri ranks third in commercial importance among fisheries in southeastern Brazil. An important management question is whether the same offseason can be applied to different regions. The population dynamics of the seabob shrimp was compared in two regions of southeastern Brazil: Macaé, state of Rio de Janeiro and Ubatuba, state of São Paulo. All demographic categories of shrimp in the Macaé region were larger than those in the Ubatuba region. Lower temperatures and greater longevities in the Macaé region may account for this difference in size from Ubatuba. In Macaé, number of reproductive females and juveniles correlated with organic-matter content. In Ubatuba, only chlorophyll-a showed a correlation with reproductive females. The reproductive period and recruitment were correlated in both populations. The difference in environmental factors between these regions, resulting of the Cabo Frio upwelling, although they are located close together, directly influences the population dynamics of X. kroyeri. The Cabo Frio upwelling may be acting as a physical barrier, preventing gene flow and differentiating the seabob shrimp stocks in the two regions. These data suggest that different offseason periods for different regions could increase the sustainability of shrimp harvesting along the Brazilian coast.

ABSTRACT.Regions affected by upwelling show environmental characteristics that may change the distribution of the species. This study evaluated the influence of environmental factors on the spatiotemporal distribution of two caridean shrimps, Nematopalaemon schmitti and Exhippolysmata oplophoroides, in a region of the Brazilian coast affected by Cabo Frio upwelling. Shrimps were collected monthly from July 2010 through June 2011 off Macaé off the northern coast of Rio de Janeiro State, at six locations: three at 5 m, and the other three at 15 m depth. Shrimp abundance was compared among seasons and sampling sites. Nematopalaemon schmitti (n = 1200) was more abundant at 5 m depth while E. oplophoroides (n = 2176) occurred predominately at 15 m. There were significant seasonal fluctuations in the distribution of the species in the region, resulting from variation in bottom temperature. The presence of the South Atlantic Central Water (SACW) favors the decrease in the abundance of N. schmitti and highest abundance of E. oplophoroides. The abundance of E. oplophoroides and the percentage of organic matter were significantly and positively correlated. The organic matter content in the sediment and water temperature was among the most important variables affecting seasonal distribution of the species. The distinct environmental characteristic between the bathymetric regions were a determinant factor in their spatial distribution.

In crustaceans, successful reproductive processes, such as the transition from juvenile to adult, exhibit important morphological changes that can be detected by analyzing relative growth. This study describes the relative growth of body structures in Nematopalaemon schmitti and its secondary sexual characteristics, and also estimates the morphological sexual maturity of this species in a region influenced by upwelling. The carapace length (CL), second pleuron length (PlL), cheliped carpus length (CaL), cheliped propodus length (PrL) and the length of appendix masculina (AML) of the shrimp were measured. The relationships that best demonstrated the changes in allometric coefficient between demographic categories were AML vs. CL for males, and PlL vs. CL for females. The estimated CL for morphological sexual maturity in males was 8.51 mm and 9.30 in females. Our results showed the appendix masculine and the second pleuron were secondary sexual characteristics that play roles in reaching the morphological sexual maturity necessary for reproductive success and to assure the life cycle of this species.

Freshwater crabs of the family Trichodactylidae are widely distributed in major river basins of the South American continent. The population structure of one species, Dilocarcinus pagei, was analyzed in an artificial reservoir in Southeastern Brazil, recording data on the sex ratio, recruitment, and mortality. A total of 1339 crabs were collected and included 804 males and 535 females (3 ovigerous and 4 with hatchlings); the sex ratio was 1:0.61 (males: females). Two modes of male and female carapace width (CW) were recorded, with means of 14.4 mm (n = 407) and 38.9 mm (n = 394) for males and 17.9 mm CW (n = 269) and 39.2 mm (n = 267) for females. The mean size of males (CW = 26.6 ± 13.8 mm) was significantly larger than that of females (CW = 28.5 ± 12.8 mm). The data indicated that recruitment occurs in summer (January-March), with the reproductive period in spring (October-December), periods with the highest rainfall and temperature values in the region. Reproduction leads to the death of the parents, influencing the sex ratio, which oscillates mainly during the reproductive period.

This study describes the weight vs. carapace length relationship and provides the total and monthly condition factor values for populations of Macrobrachium jelskii (Miers, 1977) and related to the climatic environmental factors between the two areas. Our investigation sampled M. jelskii from the Barra Mansa Dam, Mendonça, SP, a semilotic environment with greater resilience than the Talhadinho Stream, Talhado, SP, a lotic environment where specimens of M. brasiliense were captured. Individuals were classified according to sex and measured at the carapace length (CL) and weighed (WE). The relationship WE/ CL was analyzed by dispersion diagrams of the empirical points, which were set to the power function (WE = a.CL b ). Values of the mean condition factor were compared monthly. In total, 1493 individuals of M. jelskii and 843 individuals of M. brasiliense were captured. Analyses of the constant allometry revealed that both sexes of M. jelskii, as well as females of M. brasiliense grow proportionately more in size than weight. The results concerning the morphometric aspects studied in both species suggest an association with the reproductive processes.

Spatial and temporal distribution and abundance of two species of Persephona (Decapoda: Brachyura: Leucosiidae) on the southern coast of the state of São Paulo, Brazil. Biota Neotropica. 19(1): e20180534. http://dx.Abstract: Crabs of the genus Persephona are intensely captured in shrimp fisheries as bycatch in the Cananéia region off the coast of the state of São Paulo, Brazil. The analysis of the spatial and temporal distribution of Persephona punctata and Persephona mediterranea could provide information about variation in the abundance of these species, as well as the environmental variables affecting their distribution and the existence of a possible habitat partitioning. Using a shrimp fishery boat equipped with double-rig nets, crabs were monthly captured from July 2012 to June 2014 in seven sites: four in the coastal area adjacent to the Cananéia region and three in the Mar Pequeno estuarine area. The abundances of both species were compared according to spatial (among sites) and temporal (years and seasons) scale distribution. A total of 396 individuals of P. punctata and 64 of P. mediterranea were captured. The abundance of both species was higher in the second sampling year (July 2013-June 2014) and in coastal areas; only one individual of each species was captured in the estuarine area due to the low salinity at this location (approximately 27.7‰). The temperature was the environmental variable that most affected the distribution of both species, which was more abundant in warmer periods. The temporal variation in abundance was modulated by temperature, while salinity modulated the spatial distribution of P. punctata and P. mediterranea. The spatial-temporal distribution of both species differered in Cananéia, pointing to a similar use of the environment's resources. Distribuição espacial e temporal e abundância de duas espécies do gêneroPersephona (Decapoda: Brachyura: Leucosiidae) no litoral sul do estado de São Paulo, Brasil Resumo: Os caranguejos Persephona são intensamente capturados na pesca do camarão como fauna acompanhante, inclusive na região de Cananéia no litoral do estado de São Paulo, no Brasil. A avaliação da distribuição espaço-temporal pode, consequentemente, fornecer informações sobre variações na abundância de Persephona punctata e Persephona mediterranea, bem como as variáveis ambientais que afetam suas distribuições e uma possível partilha de habitat desses congêneres. Com um barco de pesca de camarão equipado com redes de arrasto duplo, os indivíduos foram coletados mensalmente de julho de 2012 a junho de 2014 em sete locais: quatro na área costeira adjacente à região de Cananéia e três na área estuarina Mar Pequeno. A abundância dessas espécies foi comparada de acordo com a distribuição espacial (entre sítios) bem como entre anos e estações. Um total de 396 indivíduos de P. punctata e de 64 de P. mediterranea foram capturados. A abundância de ambas as espécies foi maior no segundo ano de coleta (julho de 2013 a junho de 2014). A abundância de ambas as espécies foi maior na área c...