Fine-scale movement and habitat use of whitespotted eagle rays Aetobatus narinari in the Indian River Lagoon, Florida, USA

Abstract

Despite being crucial to the conservation of batoids (skates and rays), assessments of fine-scale movements and habitat use of these taxa are lacking in the scientific literature. Here we used active acoustic telemetry to characterize habitat use and movement behavior of the state-protected whitespotted eagle ray Aetobatus narinari in the Indian River Lagoon, Florida, USA. Seven mature individuals (6 males and 1 female) were individually tracked for a total of 119.6 h. Brownian bridge movement models of ray distribution showed the importance of habitats with high anthropogenic activity (i.e. boat traffic) such as inlets and channels, as well as clam aquaculture lease sites close to shore. This was supported by the significantly lower rates of movement in these habitats relative to other regions (offshore, open lagoon). Rate of movement significantly increased with temperature, suggesting that rays are more active during warmer periods. No tidal patterns in ray habitat use or distribution were evident. On average, rays used the deeper portions of the lagoon during the day and shallower portions during the night. While more extensive tracking is required to elucidate long-term movement patterns, this study is the first to characterize fine-scale habitat use by the whitespotted eagle ray in Florida while also identifying areas of potential interactions between this species and multiple anthropogenic threats.