Movement Patterns of Gray Triggerfish, Balistes capriscus, Around Artificial Reefs in the Northern Gulf of Mexico
Type of Degreethesis
DepartmentFisheries and Allied Aquacultures
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Relatively little is known about the ecology of gray triggerfish, Balistes capriscus Gmelin, despite its importance to both sport and commercial fisheries. In particular, gray triggerfish habitat use is not well understood. Fine scale tracking would provide an understanding of habitat use for gray triggerfish which may help with the future management of this species. Thus, this study was an attempt to implant ultrasonic transmitters in gray triggerfish and track their fine scale movement patterns around artificial reefs in the northern Gulf of Mexico. Adult gray triggerfish (n = 17) were successfully tagged with transmitters and tracked using the VR2W Positioning System (VPS). Most (84.2 %) tagged fish successfully survived and were tracked for extended periods (1 to 57 weeks), with only three fish lost within 24 hours of tagging (here considered a tagging artifact). Tagged gray triggerfish showed diel movement patterns with home ranges (95 % KDE) and core areas (50 % KDE) significantly larger during the day than night. Fish also showed seasonal movement patterns that were positively correlated with water temperature. Gray triggerfish showed high site fidelity (mean distance from reef = 46.3 ± 1.3 m) and residency (79 % still present after 100 days) to release site reefs. This high site fidelity could have important implications for gray triggerfish management. This species forms spawning groups around artificial reefs with a single dominant male and several females. Due to this species high site fidelity, fisher removal of the dominant male may disrupt spawning success at greater rates than previously considered. Also, the high site fidelity to artificial reefs further emphasizes the importance of structured habitat for gray triggerfish, and this new VPS tracking methods provided an important advancement for gray triggerfish movement studies.
- Herbig thesis.pdf