Use of non-invasive methods to assess the distribution and area usage by spotted eagle rays (Aetobatus narinari) in the vicinity of island marine protected areas

• Grant number: 23/13564-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2024
• End date: November 30, 2025
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Biological Oceanography
• Principal Investigator: June Ferraz Dias
• Grantee: Jaermeson Silva Santos Junior
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Elasmobranchs, with life cycles classified as K-strategists, have their susceptibility increased by anthropogenic pressures such as direct and indirect overfishing (target species and by-catch) and environmental degradation, mainly in coastal regions. In view of this, Marine Protected Areas play a fundamental role in the protection of rays and sharks. The spotted eagle ray (Aetobatus narinari) is a demersopelagic mesopredator that primarily feeds on mollusks, serving as an important link in marine food webs. It occurs from north to south in Brazil, and according to the IUCN, it is endangered, but there is limited information about its population structure and its use and/or presence in coastal areas of the country, classified as "Data Deficient (DD)" by ICMBio. To support knowledge about habitat use in two island regions (Fernando de Noronha (PE) and Ilha Anchieta (SP)), the objectives of this project are: to identify and quantify individuals of A. narinari using both areas, validate the presence of individuals in both areas, and provide information on recurrent or non-recurrent occupancy patterns of the species. Manual and open-source software photoidentification will be used on images already available from two citizen science sources, taken in the Fernando de Noronha Marine National Park and the vicinity of the Ilha Anchieta State Park. In the literature, the chosen methods result in over 85% accuracy in recognizing and identifying spotted eagle rays and can be compared in the analysis of results, supporting the understanding of area use, management, and conservation of the species.