The data modeling, which was developed by UF graduate student and study co-author Felipe Carvalho, shows only a portion of the population migrates at one time and there is a higher probability for females to arrive on the main Hawaiian Islands between September and October. Scientists tagged more than 100 tiger sharks since 2004 and collected data using passive acoustic telemetry. Sharks were recorded swimming within proximity of receivers placed at every island in the Hawaiian archipelago, which spans about 1,500 miles.
"We believe approximately one-quarter of mature females swim from French Frigate Shoals atoll to the main Hawaiian Islands in the fall, potentially to give birth," Papastamatiou said. "However, other individual sharks will also swim to other islands, perhaps because they are trying to find a more appropriate thermal environment, or because there may be more food at that island. So, what you see is this complex pattern of partial migration that can be explained by somewhat fixed factors, like a pregnant female migrating to give birth in a particular area, and more flexible factors such as finding food."
Researchers used satellite information that tracks when the sharks reach the surface to confirm horizontal movements. They also investigated environmental circumstances, resource availability, first-hand observations and data collected from previous studies to better understand varying conditions and validate their results.
Christopher Lowe, a professor in the biological sciences department at California State University Long Beach who was not involv
|Contact: Yannis Papastamatiou|
University of Florida