Batoid nurseries: definition, use and importance

Abstract

Nursery areas are crucial for many elasmobranch species, providing benefits that increase fitness and survival. Shark nurseries are well studied and our knowledge of their function and importance has expanded over the past few decades. However, little attention has been given to batoid nurseries, with studies covering less than 6% of the 663 currently described species. Threats of extinction faced by batoids reinforce the importance of defining these critical habitats. This review synthesises current knowledge of batoid nursery areas to provide a better understanding of their ecological roles and importance. Historically, different criteria have been used to define viviparous and oviparous batoid nurseries, causing confusion that could lead to failure of conservation and management strategies by under-or overestimating the importance of areas and delaying effective action. We suggest the criteria used to identify shark nurseries be applied to juvenile batoids, standardizing this nursery definition for all elasmobranchs, but we also advocate for a second set of criteria that identifies egg case nurseries. Batoids are thought to play 3 main ecological roles in nursery areas: energetic links, bioturbators and mesopredators. Biotic and abiotic features affect abundance and distribution of batoids within nurseries and likely play a key role in their habitat use. However, analysis of batoid ecological roles in nursery areas is limited by the lack of research on their early life history stages. Thus, identification of areas that support sensitive life stages and an improved understanding of early life history are crucial for the efficient management and conservation of batoid species and their nurseries.