Theses and Dissertations

Date of Award

5-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean, Coastal, and Earth Sciences

First Advisor

Richard Kline

Second Advisor

Owen Temby

Third Advisor

Juan L. Gonzalez

Abstract

East Bank Ridge is a natural reef formation located 18 nautical miles off the coast of South Padre Island, covering an area of over 80 km2, with the southern portion extending into Mexico. There is no previous record of the structural composition or fish community present at the site. The ridge was a well-known fishing site in the local community over the past decades but catch rates have decreased substantially according to personal accounts from local anglers. In this study, areas of reef habitat were identified, and fish presence and abundance metrics were determined at East Bank Ridge. These measures were compared to Sebree Banks, the closest natural reef bank, approximately 20 nautical miles north. Side-scan sonar was used to create a 2D bathymetric image of East Bank Ridge. Split beam sonar was used to define seafloor characteristics of vertical relief, roughness, and rise time at both sites and determine fish biomass and abundance estimates. Comparisons of fish abundance showed Sebree Banks had significantly greater fish abundance when scaled for area surveyed. Generalized Additive Mixed Models showed that vertical relief had the largest contribution to fish presence and biomass at East Bank Ridge. Visual surveys using a remotely operated vehicle were also conducted and nine species were identified at EBR, and six more were seen at Sebree Banks. Additionally, a questionnaire was distributed to local, long-term anglers and shrimpers to provide a baseline of historic fish presence and to identify perceived sources of degradation to East Bank Ridge. According to respondents, the fishery at EBR has declined in abundance, especially regarding the Red Snapper fishery and the main threats they identified to the fishery were illegal fishing practices from across the US-Mexico border and shrimp trawling practices. This study provides the first assessment of East Bank Ridge and identifies that the fishery is degraded when compared to a reef bank to the north, the Sebree Banks.

Comments

Copyright 2024 Marissa Lamb.

https://go.openathens.net/redirector/utrgv.edu?url=https://www.proquest.com/pqdtglobal1/dissertations-theses/investigating-demise-east-bank-ridge-through/docview/3085276619/sem-2?accountid=7119

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