Bottlenose dolphins (Tursiops truncatus) in the Texas Coastal Bend: Population abundance estimation using photo-identification

Date

2023-05-15

Authors

Wilkins, Allison

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Abstract

Common bottlenose dolphins (Tursiops truncatus) are the only species of marine mammal residing in the inshore Texas Coastal Bend (TCB). There has not been published research on their population abundance in several decades despite their exposure to a variety of natural and anthropogenic threats. The population abundances of dolphins inhabiting Corpus Christi Bay (CCB), Aransas/Redfish Bay (AB), and Laguna Madre (LM) were calculated. Vessel-based photo-identification surveys were conducted each quarter of the year in 2018 through 2022 using a closed population model to sample and resample dolphins (n = 72 surveys). Individual dolphins were distinguished by unique markings on their dorsal fins captured in photographs. Photographs were quality control checked, matched, and cataloged with metadata for population modeling. The Cormack-Jolly-Seber mark-recapture model estimated a population abundance of 1,280 dolphins in CCB, 1,105 dolphins in AB, and 1,356 dolphins in both areas. The population size estimate for LM was 408 individuals. The population of dolphins in TCB appears to have grown compared to reports from the 1980’s and 1990’s, although different survey approaches were used. Baseline population abundance data provide insights into the size and stability of the stocks of dolphins inhabiting the TCB of utility for future research and conservation efforts.

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College of Science, Life Sciences, Honors Program; Faculty Mentor: Dr. Dara Orbach

Keywords

bottlenose dolphin, Texas Coastal Bend, population abundance

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