Predictable temperature regulated residency, movement and migration in a large, highly-mobile marine predator (Negaprion brevirostris)

Understanding how and why animals are distributed through time and space has always been a fundamental component of ecology and is an essential prerequisite for effective conservation/management. However, for highly-mobile k-selected species, behavioural predictability is rarely considered over appropriate scales relative to life-history. To address this point, a multidisciplinary approach combining telemetry, external tagging, physical assessment, environmental monitoring and genetic analysis was adopted to determine a spatial framework for the movements of adult lemon sharks, Negaprion brevirostris, at multiple spatial and temporal scales from 2007 to 2011. Lemon sharks (n=83) were tracked with passive acoustic telemetry revealing a winter residency in the southeast Florida region. Detections from individuals recorded within the core winter habitat for > 20 days (n = 56) were incorporated into a generalized linear mixed-effects model (GLMM) to investigate the influence of water temperature, photoperiod, moon phase, month and year on presence. The findings of this study suggest a temperature driven “migration-residency” model for mature lemon shark distribution across the U.S. eastern seaboard. Lemon sharks are distributed across a wide geographical area in the summer months and migrate south concentrating off southeast Florida in the winter, with this pattern repeated each year. From comparative genetic analysis and the absence of any evidence of mating behaviour during the winter residency period, mating and parturition are most probably occur in May/June between northern Florida and the Carolinas. This study highlights the importance of determining the specific dynamics and proximate causes of animal movement and distribution over appropriate spatial and temporal scales relative to life-history