Variable migration patterns of whitespotted eagle rays Aetobatus narinari along Florida’s coastlines

Abstract

Basic distribution and movements of elasmobranch species, particularly mesopredatory rays, remain relatively unknown. This is especially true for the whitespotted eagle ray (Aetobatus narinari), a protected species in Florida with poorly described migratory and habitat use patterns. Passive acoustic telemetry was used to reveal multi-scale spatial patterns of A. narinari in Florida waters. Between 2016 and 2018, 54 rays were fitted with acoustic transmitters and tracked via collaborative telemetry networks. Movement patterns between the Atlantic and Gulf coast individuals were distinct; a majority of Gulf coast tagged A. narinari exhibited migratory or transient behaviors while most Atlantic coast tagged individuals remained resident in the Indian River Lagoon (IRL). On both coastlines, water temperatures during times when A. narinari were present were significantly warmer (mean\u2009=\u200927.8\xa0°C) compared to temperatures when A. narinari were absent (mean\u2009=\u200924.9\xa0°C), suggesting temperature may be a major abiotic factor influencing migration patterns. Ontogenetic shifts in habitat use were evident along the Atlantic coast in the IRL, but not along the Gulf coast. Immature rays spent significantly more time (mean\u2009=\u200991.5%) inside the IRL compared to mature counterparts (mean\u2009=\u200960.2%). This is the first multiyear study to examine large-scale movements of A. narinari in U.S. waters and results may be important for adaptive management strategies throughout this species’ range. Importantly, our work suggests potential sub-population structuring of A. narinari may be occurring more than previously considered\xa0within Florida, which has significant conservation implications for this species.