Ecologia da raia, Dasyatis americana (Hildebrand & Schroeder, 1928), na Região Metropolitana do Recife - PE e na ReBio Atol das Rocas - Brasil

Abstract

The south stingray is commonly captured as by-catch in different fisheries, not only in Brazil but also in some parts of South America, and due to the deficiency of available data, there is now a considerable deficit of information to evaluate the population status of the specie. In this context, the main goal of this study was to investigate aspects related to the ecology of the D. americana along the coast of the metropolitan area of Recife, from capture data and acoustic monitoring, and in the Biological Reserve of Atol das Rocas, from observation and movement analysis. On the coast of Recife CPUE´south stingray was higher in Boa Viagem / Piedade (0.33) than in Paiva (0.26). The average monthly CPUE on the beach of Boa Viagem / Piedade was higher in May, while on the beach of Paiva the highest value occurred in June. The annual CPUEs, to the beaches in combination, were higher at the research beginning in 2004 and 2005. Of the 85 specimens, it was possible to identify the sex in 17 animals, of which 16 were females, with DW ranging between 79.00 and 152.00 cm (124.63 ± 20.86), DL between 94.00 and 142.00 cm (113.08 ± 14.14), and TL between 97.00 and 255.00 cm (188.31 ± 54.97); and only one was male, with DW 87.00 cm. Throughout the research was also recorded the occurrence of a food item (Dasyatis marianae) unusual, never described before for D. american diet. The evaluation of the detection from the acoustic monitoring on the reef coastline, in relation to the 24 hour cycle indicated that the majority of the detections occurred over night (96.4%) (X² = 144.857; P <0.0001). The TAH values were higher in the years 2003 (0.76 ± 1.51) and 2008 (1.55 ± 1.76), observing, between 2009 (0.15 ± 0.42) and 2013 ( 0.21 ± 0.57), values consistently lower. The significant decrease of species sightings within the Rocas Atoll raised the possibility of there being a natural population decline in the region. The vertical habitat use pattern for the D. americana showed a strong preference for both tagged stingrays (91.4% and 86.3%, respectively) by hot water (above 28 ° C) and shallow (depths up to 5m) of Rocas Atoll over the monitoring period. The results showed that low depth areas as one of the essential habitats for specie inside to Rocas Atoll. Finally, it is essential that greater efforts are seeking in employees the continuation of an adequate monitoring of their populations in coastal and island waters.