Identifier

etd-04122007-135119

Degree

Master of Science (MS)

Department

Biological Sciences

Document Type

Thesis

Abstract

The black drum, Pogonias cromis (Sciaenidae), is a molluscivorous, coastal/estuarine species, often associated with oyster reefs, that is sought in recreational and commercial fisheries. I used a radio-acoustic positioning system and an array of moored receivers to monitor movements of 34 black drum around oyster reefs in Barataria Bay, Louisiana from March 2006 to February 2007. Residence time was variable; five fish were detected almost daily for more than 60 days, but others only on the day of release. Daily movements exceeded spatial coverage, and home range sizes could not be determined. Short-term site fidelity to reefs was higher in the fall than spring. Long-term site fidelity was observed with 64% of fish released in the spring returning in the fall. Diel activity on oyster reefs was nocturnal during warmer months and corresponded closely with twilight, but was diurnal in cooler months. Diel movement was more rapid shortly before sunset and after sunrise and slower during the night. Movement rates are among the slowest observed with a positioning system, 8-14 meters/minute. A geographic information system was used to examine spatial and habitat use. A habitat selection index (HSI) showed preference for oyster reef habitat, avoidance of soft sediment, and no selection for marsh edge. Conventional tag and release methods were used simultaneously to determine long-distance movement, local abundance, and to test whether catch and release deters predation on oysters. Of 790 fish tagged, five were recaptured, four at the site of release. Oyster mortality was decreased in the spring due to the disturbance involved in mark and recapture, but not the fall, and a correlation was found between increasing catch and dissolved oxygen concentrations. From an oyster management perspective, short-term removal of fish is not likely to increase oyster survival due to extensive daily movements and immigration.

Date

2007

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Kenneth M Brown

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