Photo identification on the flukebook platform reveals aspects of the behavioral biology of sotalia guianensis in Rio Grande do Norte and Paraíba states, Brazil

Abstract

Cetaceans are affected by ecological factors such as the distribution of prey and predators, physical water conditions, as well as anthropogenic factors such as the rate of accidental and/or intentional captures, habitat degradation, pollution, and the increase in vessel traffic. These ecological influences can change the behavior of individuals, resulting in alterations in habitat use and species distribution. The collection of baseline demographic information is important for identifying these changes and for the management and conservation of marine species like the Guiana dolphin, Sotalia guianensis, which is still little known in the northeastern region of Brazil. One way to collect these data is by generating catalogs for the identification of individuals and their distribution over time and space, enabling long-term studies that use natural markings on the dorsal fin. The main objective of this study is to generate one of these catalogs through the use of the Flukebook platform, utilizing the four algorithms available on the website, and analyzing the photos belonging to the UFRN archive (ARC - Archive for Research and Conservation of Images and Sounds from Nature) obtained between Tabatinga-RN and Cabedelo-PB. This catalog resulted in the identification of 64 individuals, 59 of which were re-sighted during the collection period (2005 to 2023), with four of the re-sightings being females located in or around the Reserva de Fauna Costeira de Tibau do Sul (REFAUTS) reserve. These results indicate the REFAUTS reserve represents an important habitat for maternal care. The results also revealed that some individuals use more than one bay in the region, with a certain fidelity degree. Another important result obtained through the re-sighting of individuals was an estimate of longevity in the region, whicha minimum established at one year and maximum of 11 years. The urgency in understanding the behavioral ecology of this cetacean arises the species being coastal, having a low reproductive rate, and vulnerable to extinction. Data such as those from the present study, which gathers longitudinal data (2005 to 2023) on the spatial distribution of Sotalia guianensis in the northeastern region, whose population was determined as BRNE2, allow us to estimate trends in abundance and distribution over time, giving us clues about population health and individual behavior, as well as facilitating the discovery of potential feeding, reproduction, and nursery sites that are conservation priorities for the species.