Enhancing multitasking capacity: An acoustic tagging and sampling methodology for the spiny butterfly ray (Gymnura altavela) in the Canary Islands

Abstract

Challenge: The depletion of elasmobranch populations and limited access to these species have posed significant challenges for researchers aiming to study sharks and rays effectively. Response: Consequently, novel techniques have been developed to enhance knowledge of these species within the marine environment. Target species: Our focus has been on the spiny butterfly ray, a benthic species that spends portions of its life cycle near the coast in shallow areas. Methodology: Between 2020 and 2024, 133 individuals of spiny butterfly ray were internally tagged in Gran Canaria and Tenerife using a combined double tagging approach, employing acoustic and external T-bar tags. Additional data collection: During the same procedures, skin, gill, and anal orifice swabs were obtained to analyse microbiota; blood samples were collected to assess stress levels and hormonal profiles; and in situ ultrasound examinations on females were performed to evaluate pregnancy status. Morphometric measurements were also recorded for future growth and age studies. Operational efficiency: All these processes were conducted simultaneously through coordinated efforts among sub-teams, enabling the complete methodology to be completed in less than 8 min per individual. Practical implication: Solution: This integrated, rapid approach demonstrates an effective model for minimally invasive, multifaceted research on elusive benthic elasmobranchs, potentially informing conservation strategies and further ecological understanding.