Publication Date

2016-12-14

Availability

Open access

Embargo Period

2016-12-14

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Marine Affairs and Policy (Marine)

Date of Defense

2012-12-12

First Committee Member

Neil Hammerschlag

Second Committee Member

Maria Estevanez

Third Committee Member

Jill Richardson

Abstract

The purpose of this project was to identify the effects of various environmental factors (sea surface temperature, salinity, sea surface currents, and Earth's magnetic field intensity) on tiger sharks (Galeocerdo cuvier) movements in the Atlantic Ocean, with a primary focus on the influence of Earth's magnetic field. Previous studies concluded that several species of sharks are capable of detecting small electromagnetic pulses under controlled experimental conditions, however evidence is lacking regarding sharks utilize the Earth's magnetic field to navigate the open ocean. To investigate this, four mature female tiger sharks were satellite tagged and tracked for a minimum of 6 months and a maximum of 10 months. Geographic Information Systems (GIS) were used to analyze how the aforementioned environmental factors influenced the sharks' movements. Sea surface temperature and salinity appear to play minor roles in shark distribution patterns, and sea surface currents appeared to have little influence on the sharks' direction of movement. A relationship was found between shark movements and the Earth's total field intensity; while traveling offshore, the sharks occurred over a wide range of magnetic field intensities, which may suggest that these sharks are able to recognize an increase and decrease in Earth's magnetic filed values as they move to and from their desired destination.

Keywords

Tiger Shark; Shark; Navigation; Magnetic Field; Environmental Factors

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