Important Shark and Ray Areas for pelagic, migratory data-deficient species: A case study of Mobula hypostoma in the northern Gulf of Mexico

The identification of Important Shark and Ray Areas (ISRAs) represents a critical approach to supporting the conservation of vulnerable elasmobranch species globally. ISRAs are science-based designations for spatially significant habitats essential for the survival and recovery of various shark and ray populations. Their establishment relies on a rigorous set of criteria that assess ecological importance, such as the presence of essential life-history stages, critical migratory routes, and unique population assemblages. However, defining precise ISRAs for data-deficient, often pelagic and migratory, elasmobranch species is challenging. These include the Atlantic pygmy devil ray (Mobula hypostoma), a pan-Atlantic species for which data on population structure, habitat use, and seasonal movements remain limited.

In this presentation, we describe the criteria and methodological framework for identifying ISRAs applied to a poorly documented species, M. hypostoma, in the northern Gulf of Mexico. In this case study, various observational and analytical methods including citizen science sighting reports, acoustic and satellite telemetry, stable isotope ratios as biomarkers, species distribution modelling and population genomics are used to understand the spatiotemporal distribution of M. hypostoma in the study region, as well as the ecological value of the habitats (with regard to feeding, mating, birthing grounds, nurseries and migration corridors) frequented by the species. Our results indicate that M. hypostoma undertakes significant seasonal migrations – likely driven by seasonal prey availability – between West Central Florida and the northern Gulf. Upon reaching maturity, an ontogenetic shift occurs, with juveniles and subadults primarily feeding in shallow coastal waters while adults predominantly forage offshore in deeper waters, along the continental slope and in canyons, with dives reaching depths of up to 180 meters. The Emerald Coast in Florida appears to provide critical foraging habitat for juveniles and subadults (individuals less than 100 cm disc width), with some individuals residing in the area for up to six months annually.

Based on these findings, we propose two candidate ISRAs for M. hypostoma in the northern Gulf of Mexico: the Emerald Coast as a primary feeding ground, encompassing the shallow coastal waters and the head of the DeSoto Canyon; and the waters connecting this region to West Central Florida as a vital migration corridor. These preliminary areas of interest will be submitted to the Independent Review Pannel for evaluation during the North American and Caribbean Atlantic regional workshop (2025).

Our findings illustrate how rigorous biodiversity observation and monitoring efforts can enable scientists to identify and designate ISRAs. By generating actionable, data-driven insights, ISRAs offer decision-makers and stakeholders essential information for implementing targeted conservation measures within broader marine protected area networks. This approach exemplifies a pathway to more informed, equitable, and ecosystem-based conservation strategies that bridge science and policy for the benefit of marine biodiversity.