Identifier

etd-07112011-132809

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

The Gulf of Mexico (GOM) red snapper stock has been exploited since the mid 1800s; yet it is still one of the most economically important fisheries in the GOM. Red snapper have been managed as a unit stock and are currently overfished, but perhaps no longer undergoing overfishing. Habitat varies greatly throughout the GOM and while numerous studies have aged red snapper, none have simultaneously compared the age and size structure and growth rates among standing and toppled oil and gas platforms with natural habitats. The objectives of this study were to examine the size and age structure and growth rates of red snapper among three different habitats (shelf-edge banks, standing platforms, toppled platforms) and six recreational fishing regions of the GOM (South Texas, North Texas, Louisiana, Alabama, Northwest Florida, Central Florida). Across all of the habitats and regions, red snapper were small (mean TL = 526.84 mm, mean TW = 0.97 kg) and from younger age classes (mean age = 4.44 yr), representing the strong recruitments of 2004, 2005 and 2006, with few fish older than seven years (1.5%). Total length, weight, and age frequencies, and growth models differed significantly among the habitats. Red snapper from the banks were significantly smaller at age and slower growing than red snapper from the artificial habitats. Also, shelf-edge banks appear to support a higher predominance of older red snapper compared to the artificial habitats. Demographic differences in red snapper size and age frequencies and growth parameters exist across the GOM. Small, fast-growing individuals dominated the recreational catches of South Texas, Northwest Florida, and Central Florida, whereas larger, slower growing red snapper constituted the majority of the Alabama and Louisiana catches. Also, both of the Florida regions’ catches were comprised of significantly younger red snapper than catches in the north-central and western regions. To prevent habitat- and region-specific overfishing and promote stock recovery, these differences should be weighed when evaluating future stock assessments and management decisions. It is also important for fisheries managers to note the absence of old red snapper in this study and its implications for the stock’s recovery status.

Date

2011

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cowan, James H

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