Caracterização dos encalhes de tartarugas marinhas no litoral norte de São Paulo e a influência das ameaças antropogênicas associadas

Abstract

Sea turtles are aquatic reptiles with a high migratory capacity, distributed along the Brazilian coast, alternating between feeding and nesting areas. Of the seven species in the world, five occur in Brazil. All over the world, a reduction in the populations of sea turtles has been recorded, with an increase in the number of records of strandings being increasingly recurrent, and currently all species being on the Brazilian coast are, at different levels, threatened with extinction. Bycatch and solid waste contamination are one of the main threats to non-target organisms. The analysis of sea turtle stranding patterns allows inferences about aspects of biology and ecology, compiling data on mortality, distribution, diet, sex ratio, feeding areas, spawning and diseases. In this study, (i) we analyzed the effects of seasonality on the abundance of stranded sea turtles, (ii) we verified whether there is a distinction between the sex and developmental stage of stranded sea turtles and (iii) we evaluated whether human activities can contribute to strandings or for greater viewing of beached sea turtles. Stranding data were collected over a six-year interval (2015-2021), on 235 beaches located in the the northern coast of the State of São Paulo, municipalities of Ubatuba, Caraguatatuba, São Sebastião and Ilhabela, on the northern coast of the State of São Paulo, obtained through active daily monitoring and passive and made available on the SIMBA/PMP/BS public domain platform. During the five years of monitoring, 6411 sea turtle strandings were recorded, the majority being Chelonia mydas (n = 5812), Caretta caretta (n = 313), Lepidochelys olivacea (n = 116), Eretmochelys imbricata (n = 61) and Dermochelys coriacea (n = 9). These strandings were reported mainly by the population. Most stranded animals were dead, in an advanced stage of decomposition, and in the juvenile stage of development. Strandings occurred mainly in winter and spring. In animals in which it was possible to determine the cause of death, the main associated anthropogenic factors were fishing gear, injuries from collisions and ingestion of solid waste, such as plastics. The regularity of monitoring programs on beaches in southeastern Brazil made possible studies that suggest to an increase in the frequency of strandings of sea turtles and a pattern of these strandings for the coast of the Southeast, with records for the five species that occur in Brazil. This study demonstrates the importance of monitoring along the Brazilian coast, enabling the collection and study of stranding data, which help to understand the dynamics of marine ecosystems and the main threats to be considered in management and conservation plans. It is necessary to expand environmental and oceanic education activities, promoting reflection on environmental issues, raising awareness and democratizing the participation of different sectors of society.