Abstract We estimated the growth patterns, age at the onset of sexual maturity, longevity, and natural mortality of the snapping shrimp Alpheus brasileiro Anker, 2012. The sampling occurred monthly from April 2015 to March 2016 in the estuarine intertidal zone of Cananéia, São Paulo, Brazil. To estimate the growth parameters, all cohorts were adjusted to the Bertalanffy growth model. Longevity was estimated by the inverse growth equation. Natural mortality was calculated following the decrease in abundance over time of each cohort. We obtained the following estimates: CL∞ = 9.49 mm, k = 0.0077 day-1 (1.64 year-1), t0 = - 0.7628 for males, and CL∞ = 9.31 mm, k = 0.0095 day-1 (1.32 year-1), t0 = 0.0374 for females. The estimated age at the onset of morphological sexual maturity was 94 and 74 days for males and females, respectively. Females take 89 days to reach functional maturity, and have a higher mortality (4.35 year-1) than males (3.67 year-1). We rejected the hypothesis that males and females of A. brasileiro have the same growth patterns, longevity, mortality and, reaches sexual maturity at the same age. Our results suggest that physiological aspects and energy allocation strategies modulate the growth, longevity, and mortality of these snapping shrimps.

Abstract We investigated the abundance and spatial distribution of Callinectes danae Smith, 1869 during the day/night periods and tidal cycles in a coastal area of Brazil. Sex ratio, size class distribution, and mean sizes of males and females were also analyzed. The sampling occurred between February and March 2011 in the estuary-bay complex of São Vicente. Collections occurred in six sampling stations during both daytime and nighttime. A total of 1997 specimens were collected in the bay and 963 specimens in the estuary. The abundance of males and females differed between the bay and estuary, with males more abundant in the estuary and adult females in the bay. Crabs in all demographic categories were more abundant at night. The species distribution was intrinsically related to the interaction between environmental factors. In addition to the higher capture during nocturnal collections, a positive correlation was found between the abundance of reproductive females and salinity, while juveniles were more abundant in shallower stations and at lower salinities. Our results contribute to a better understanding of the influence of day/night periods and tidal cycles on the abundance and distribution of the swimming crab C. danae.