A review of batoid philopatry, with implications for future research and population management

Animal movements, in particular residency or return migrations (collectively de fined as 'philopatry'), can shape population structure and have implications for management. This review examines the evidence for philopatry in batoids, which are some of the least understood and most threatened vertebrates, and updates a prior review of the same in sharks. Evidence for philopatry in batoids was found in 46 studies, including 31 species that involve 11 species complexes. Batoid philopatry research has lagged behind shark philopatry research, with the annual publication rate of shark philopatry studies in the last 5 yr (17 yr(-1)) being more than twice that of batoids (7 yr(-1)). Philopatry research on both sharks and rays is taxonomically skewed: < 50% of elasmobranch families are represented. Research is also skewed towards charismatic megafauna (white sharks, whale sharks, and manta rays), while the batoid philopatry literature is biased towards 'Near Threatened' species, even though approx. 47.5% of batoids are considered to be 'Data Deficient' by the IUCN. Limited evidence was found for residency in batoids, contrary to popular assumptions that they are sedentary, and there was limited evidence for sex-differentiated movements. Hypothesis-driven research, longer study durations, more taxon and life stage diverse studies, and consistent use of philopatry terminology are needed to advance the fields of batoid philopatry and conservation. Given strong evidence of philopatry in some species of batoids, management should proceed at the local scale until more studies are conducted.