Theses and Dissertations

Title: Long-term residence and diel movements of red snapper on artificial reefs in the northern Gulf of Mexico

Name: Schroepfer, Rebecca L.

Degree: MS

Chair: Stephen T. Szedlmayer


University: Auburn University

Location: Auburn, Alabama

Date: 2004

Pages: 80

Keywords: red snapper, Gulf of Mexico, artificial reefs, reefs, residence and diel movements, Lutjanus campechanus


Red snapper Lutjanus campechanus (N = 54) were tagged and tracked on 12 artificial reefs in the northern Gulf of Mexico. Fish were surgically implanted with ultrasonic transmitters and monitored with Vemco remote receivers and Sonotronics surface receivers from August 2000 to January 2004. Four fish were manually tracked from the surface overnight with positions recorded every hour for 16 h. Mean ? SE total length offish tagged was 589 ? 14 mm. Mean ? SE detections by the remote receivers was 239,753 ? 38,004. Red snapper were resident on artificial reefs for a mean ? SE of 243 ? 35 d, with a range of 23-595 d. Fish were resident on the same artificial reef for three to six seasons (winter, spring, summer, fall). Red snapper showed changes in proximity to reefs with season, and were significantly closer to the reef from August to December. Red snapper left the receiver range (1.6 km) for certain periods of time, e.g. fish 25 left the reef 285 times for 1-4 h. However, all fish spent most time within the receiver range (mean ? SE = 98 ? 1%). No relation was detected between fish size and length of residency on an artificial reef. Tagged red snapper showed longer residence on some artificial reef sites compared to others. Four fish tagged with Vemco transmitters and monitored with remote receivers varied in proximity to the reef over 24 h cycles. Two fish were further from the reef during the afternoon and two fish were further from the reef at night. Four fish tagged with Sonotronics transmitters and manually tracked for 16 h from the surface also showed diel movements. These fish used a larger area at dusk and were closer to the reef at dawn. Mean ? SE area used was 2,314 ? 563 m2 and mean ? SE distance from the reef was 29 ? 2 m. In this study, red snapper showed high site fidelity over long time periods, as some fish were resident on particular artificial reefs for greater than one year.

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