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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.

This study tested for social monogamy inAlpheus brasileiroAnker, 2012. We also analysed egg production in this species. Sampling was conducted bimonthly from March 2013 to January 2014, and specimens were collected manually in the intertidal estuarine zone of Cananéia, São Paulo, Brazil. A total of 186 specimens (92 males and 94 females) were captured, and ~46% of them were found living in heterosexual pairs. The carapace length (CL mm) of paired males and females was positively correlated. We analysed 35 females carrying eggs underneath the abdomen: 28 of these females had eggs in stage I of development, four had eggs in stage II, and three had eggs in stage III. The average (±SD) mean fecundity for females carrying early (stage I) eggs was 149 (±93) eggs. Egg volume differed significantly among developmental stages, with a 35.4% increase in egg volume between stages I and III. The egg volume and size (CL) of females correlated positively. A positive correlation between the number of eggs and carapace length was found, with a proportional increase in the number of eggs according to the size of females. Our results suggest that the studied population ofA. brasileirois socially monogamous and provide the first insights into egg production in this species.

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.

This study estimated the sexual maturity of Dilocarcinus pagei Stimpson, 1861 based on relative growth and gonadal development. In addition, a possible sexual dimorphism was reported. The specimens were monthly captured from October 2005 to September 2007 in the Marimbondo/Furnas Hydroelectric Plant Reservoir, municipality of Icem in northwestern São Paulo State. Handedness was recorded for males, with the right cheliped propodus invariably longer and wider than the left. The estimated carapace width for morphological sexual maturity in males was 28.7 mm, based on the biometric relationship of the cheliped propodus length vs. carapace width; for females, this value was 24.2 mm, using the relationship of the abdominal width vs. carapace width. The size at gonadal maturity was estimated at 39.2 mm and 39.9 mm, for males and females respectively (CW50). There was not sexual dimorphism in relation to carapace width. For a crab to be able to procreate, it must reach morphological maturity and have developed gonads. Thus a minimum capture size based on the size, at which 50% of the population is considered reproductive, can ensure the continued preservation of this species.

Hermit crabs are soft-abdomen decapods. They depend upon gastropod shells for protection, with the latter influencing growth rate, mortality and reproduction. The present work aims to provide information about the biology and reproduction of Pagurus brevidactylus in a conservation area in Brazilian southeastern littoral. The material was sampled through active searching by SCUBA diving and refuge traps. We analyzed population structure, fecundity, reproductive output (RO), reproductive periodicity and shell utilization for P. brevidactylus. In total, 54 males, 18 nonovigerous females, 34 ovigerous females and 10 juveniles were sampled. The females had a fecundity of 69.5 ± 65 eggs, which was lower than that compared to other populations from different localities. The RO ranged from 1.48% to 63.04%, with a mean of 26.75 ± 18.23%. There was a positive relationship between egg number and female size. The animals had continuous reproduction, but they reached smaller maximum sizes when compared with other populations. The shell occupation pattern was also different from other localities, the shells of Phrontis alba being the most occupied; this shell has a smaller size when compared to others that P. brevidactylus occupies in other localities. Therefore, P. alba could have had limited the growth and reproduction of P. brevidactylus.

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