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Spatiotemporal Movements of Common Bottlenose Dolphins (Tursiops truncatus truncatus) in Northeast Florida, USA
Abstract: Common bottlenose dolphins (Tursiops truncatus truncatus) (hereafter referred to as “dolphins”) are distributed along the east coast of Florida in a longitudinal continuum within inland waterways and federally managed via assignment into stocks. Seven regional studies have identified local estuarine populations with resident and seasonally transient dolphins. However, study area boundaries limit understanding of distribution and movement patterns between these geographically separated regions. To reveal the bigger picture of spatiotemporal movements, a multi-organizational consortium conducted semiannual photo-identification surveys from the Florida–Georgia border to Titusville, Florida (331 km). The study area incorporated dolphins occurring in the Jacksonville Estuarine System (JES) stock in the north, the Mosquito Lagoon within the Indian River Lagoon Estuarine System (IRLES-ML) stock in the south, and the connecting 156-km inland waterway currently managed under the Western North Atlantic Northern Florida and Central Florida coastal stocks. The area was divided into segments, and simultaneous surveys were conducted from 2011 to 2016 during two primary sampling seasons within each year: five summers and five winters (primary period), with two to three surveys (secondary sessions) within each primary period separated by one-week intervals to allow mixing of the population. A total of 6,896 dolphins, including 196 neonates, were observed, and 649 individuals were identified. Spatial autocorrelation analyses of 222 marked dolphins sighted in ≥ 5 primary surveys revealed that 78% exhibited significant regional and seasonal fidelity to one or more segments, which no single study could elucidate. Additionally, JES-North dolphins demonstrated strong regional site fidelity and were consistently sighted during both seasons, similar to studies in the 1990s, and continued to be partitioned from dolphins to the south. JES-South and IRLES-ML dolphin home ranges extended beyond previously known boundaries. Based on spatiotemporal movement patterns between the segments, recommendations are made to revise boundaries of the JES and IRLES stocks.
Key Words: common bottlenose dolphin, Tursiops truncatus truncatus, Northeast Florida, Jacksonville Estuarine System stock, Indian River Lagoon Estuarine System stock, St. Johns River, Mosquito Lagoon, site fidelity, movement patterns
Page Numbers: 285-300