Movements and Home Ranges of Alligator Gar in the Mobile-Tensaw Delta, Alabama

Alligator gar (Atractosteus spatula) populations have declined across the species' historical range. Therefore, data on movements and home ranges of alligator gar are needed to evaluate potential management scenarios. The movements of 12 alligator gar were monitored using radio and sonic telemetry in the Mobile-Tensaw Delta, Alabama, from June 1998 to April 2000. Fish were fitted with external radio transmitters (N = 5) from June to October 1998 and sonic transmitters (N = 10) from March to May 1999. Seven fish were released in Threemile Creek in the western delta, three fish were released in the central delta and five fish were released in the eastern delta. Twelve of 15 alligator gar were located at least once after tagging. Fish were relocated from one to 19 times, and total observed movement was highly variable (1.55-23.10 km). Linear home ranges of fish ranged from 2.73 to 12.25 km. Distance moved per relocation increased with fish size (r2 = 0.32, P = 0.05), and the number of relocations decreased with fish size (r2 = 0.51, P < 0.01). A relationship (r2 = 0.42, P = 0.16) was not found between home range and fish size. Management strategies should incorporate these new data which suggest that juvenile alligator gar exhibit site fidelity and large individuals are highly mobile.

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