Renata A. Shinozaki-Mendes

Population structure of nurse sharks, Ginglymostoma cirratum (Orectolobiformes), caught off Ceara State, Brazil, south-western Equatorial Atlantic

The nurse shark, Ginglymostoma cirratum, is considered an endangered species in Brazil and its capture by fisheries forbidden. Despite such legislation, nurse sharks continue to be caught as these laws are unenforced and fisheries are not monitored. The goal of the present study was to describe the population structure of nurse sharks caught off Ceara State, north-eastern Brazil, based on the following aspects: abundance and size, sex-ratio, fisheries incidence and seasonality of captures. Landings were monitored weekly during a two-year period. A total of 1 8 9 specimens were recorded. Total length (TL) varied between 73 and 274 cm. The male-female ratio did not differ significantly (1.19♀:1♂). TL of individuals landed as carcasses was estimated based on interdorsal length. The following equation was obtained for males and females: TL = 12.606ID + 14.24 (R 2 = 0.9505). Most of the landed sharks were juveniles (86.2%). No seasonal pattern of abundance and TL variation was observed. Management of this fishery is required in order to prevent localized over-fishing of nurse sharks.

Histochemical study of the ovarian development of the blue land crab Cardisoma guanhumi (Crustacea: Gecarcinidae)

The reproductive tract of female Cardisoma guanhumi was macroscopically and microscopically described. The stages of sexual maturation were defined and related to gonad coloration and to the degree of development of the germ cells, including oogonia (diameter 14.17 ± 0.97 µm), forming nests in the germ zone; pre-vitellogenic oocytes (PVO, 51.02 ± 2.90 µm) of a basophilic nature, with one or two nucleoli; vitellogenic oocytes (VO, 110.93 ± 7.04 µm) of acidophilic nature; mature oocytes (MO, 237.52 ± 13.54 µm), revealing the chorion; and atretic oocytes (AO). Follicular cells were found close to germ cells. The following gonad development stages were identified: immature (translucent color, germ zone containing oogonia, and peripheral maturation zone with PVO); maturing (color ranging from yellow to dark brown; maturation zone with VO); mature (dark brown color; predominance of MO in maturation zone); spawning (dark brown or yellow color, containing oocytes in early atresia, stage observed in ovigerous females); and resting (translucent to yellow color, thick gonad wall, and residual AO).

The influence of environmental factors on the abundance of swimming crabs (Brachyura, Portunidae) in a tropical estuary, northeastern Brazil

Swimming crabs (family Portunidae) were collected in Santa Cruz Canal, Brazil from March 2009 through February 2010 using a beach seine and fishing line. The purpose of this study was to characterize the abundance of portunid crab species and to analyse the influence of environmental factors on the catches per unit effort (CPUE) values of Callinectes danae Smith, 1869 in the canal. The catches included five species: C. danae (the most abundant species), Callinectes marginatus (A. Milne-Edwards, 1861), Callinectes exasperatus (Gerstaecker, 1856), Charybdis hellerii (A. Milne-Edwards, 1867) and Callinectes bocourti A. Milne-Edwards, 1879. The species could be assigned to groups according to their abundance and the values of catches were higher during the dry period. The influences of water temperature, tide height, lunar illumination, salinity, precipitation and season were tested, although the average CPUE (μ) of C. danae for the beach seine and line methods was influenced only by tide height (T) and by salinity (S), according to the model: μ seine = exp ( 3 . 4921 − 1 . 3584 T ) and μ line = exp ( 0 . 055589 S ) . Within the ranges of the environmental variables included in the study, a tide height of 0.1 m was found to optimize the CPUE of the beach seine (28.68 Ind/h per m2). Furthermore, the CPUE using the line was optimized as the salinity level increased, with a capture rate of 05.92 Ind/h.

Estimativa da batimetria do açude do Saco-PE com auxílio de dados orbitais

The bathymetry of a water body can be measured in the field using bathymetric probes; however this process is costly and time-consuming. Thus, the main objective of this study was to fit bathymetry estimation models of a lake from satellite data. The study was conducted in the Saco reservoir, located in the Pajeu river basin near the city of Serra Talhada - PE, Brazil. Regression models were adjusted between the bathymetry values collected with a probe, the green and near infrared spectral bands of the Landsat 5 TM satellite and the normalized difference water index. Evaluation of the adjusted models was performed by analysis of the coefficient of determination, mean squared error and model efficiency. The bathymetry of the reservoir varied between 0.3 and 10 meters deep. The best fits were found when using the power and exponential models, with coefficients of determination greater than 0.46 and model efficiency close to one. It can be concluded that the bathymetry models adjusted to the remote sensing data provided a satisfactory accuracy for estimating bathymetry values of the Saco reservoir, especially in the shallow regions of the lake.