Conservação e manejo do tubarão-lixa, Ginglymostoma cirratum, (Bonnaterre, 1788), (Orectolobiformes: Ginglymostomatidae): revisão de pesca, potencial distribuição, reabilitação e fisiologia digestiva

Abstract

The nurse shark (Ginglymostoma cirratum) is a species found in tropical and subtropical regions of the Atlantic Ocean, currently classified as “Vulnerable” to extinction by the International Union for Conservation of Nature (IUCN), mainly due to overfishing. In the first chapter, a review of the literature on its capture was conducted, identifying records in 26 locations from nine countries in the Americas and Africa, involving artisanal fishing (10 locations), accidental capture (6), landing (3), and sport fishing (1). Nets, longlines, traps, and spearfishing stand out among the methods used. Although fishing for this species is prohibited in countries such as Brazil, Colombia, and Guinea-Bissau, conservation strategies were identified in almost all the countries analyzed. In the second chapter, species distribution modeling (SDM) was used to estimate the potential distribution of G. cirratum in the Western Atlantic, using records from global occurrence platforms and environmental variables obtained from Bio-ORACLE. The algorithms used were BIOCLIM, Domain, Generalized Linear Model (GLM), and Random Forest (RF), all of which performed satisfactorily (AUC > 0.7). The most relevant predictors were dissolved oxygen (BIOCLIM), pH and temperature (Domain), bathymetry (GLM) and primary productivity (RF). The models indicated a high probability of occurrence in island regions, particularly the Antilles, Cuba, Fernando de Noronha, Trindade and Martim Vaz, the Bahamas, and the edge of the continental shelf. Considering the species' low mobility and fidelity to specific habitats, which favour population isolation between continental and island regions, the importance of genetic studies on the species is emphasized. The third chapter presents a case study on the rehabilitation and release of a Ginglymostoma. cirratum specimen, with the aim of establishing a first aid and clinical care protocol for elasmobranchs. Rescued in a state of circulatory shock and moderate dehydration, the animal was referred to the Associação de Pesquisa e Preservação de Ecossistemas Aquáticos (AQUASIS), where it received intensive treatment involving fluid therapy, antibiotics, antiparasitics, and laboratory tests. Following the absence of leukocytosis and mercury toxicity after treatment, the animal was deemed fit for release and was released into the Parque Estadual Marinho da Pedra da Risca do Meio. This case study highlights the necessity of specialized infrastructure for the rehabilitation of elasmobranchs, which remains limited in many centers dedicated to marine fauna. Finally, the fourth chapter aimed to characterize the gastrointestinal transit (GT) time of the Atlantic nurse shark. This information is important for managing individuals in human care, particularly in environments such as aquariums, where the species is commonly kept due to its low maintenance requirements. Using contrast-enhanced barium sulphate ultrasound, the total GT was found to be 23 hours and 56 minutes, with no evidence of morphological changes or intestinal obstructions. These data are relevant for optimizing feeding protocols and assessing animal welfare under human care. Finally, the fourth chapter aimed to characterize the gastrointestinal transit time (GIT) of the Atlantic nurse shark, using contrast-enhanced barium sulphate ultrasound, the total GIT was found to be 23 hours and 56 minutes, with no evidence of morphological changes or intestinal obstructions. These data are relevant for optimizing feeding protocols and assessing animal welfare in human care.