Date of Award

8-2021

Degree Type

Honors College Thesis

Academic Program

Marine Biology BS

Department

Biological Sciences

First Advisor

Nicole M. Phillips, Ph.D.

Advisor Department

Biological Sciences

Abstract

The Critically Endangered smalltooth sawfish, Pristis pectinata, was historically found throughout tropical and subtropical coastal waters of the Atlantic Ocean. As a result of mortalities in fisheries and habitat degradation, they became largely restricted to southwest Florida in the U.S. and the Bahamas by the 1980s. However, recent public encounter reports of sawfish in the Florida panhandle, Mississippi, and Louisiana suggest this species is occasionally present in northern Gulf of Mexico waters. Targeted species surveys are needed to improve our understanding of the occurrence and status of this species in these waters. This research used environmental DNA (eDNA) methods to assess the presence of P. pectinata in waters off the Chandeleur Islands, Louisiana. Water samples from 20 sites on the northwestern side of the Chandeleur Islands were collected and filtered in 2019. DNA was extracted from these samples, and these extracts were screened for target DNA using species-specific quantitative PCR and Droplet Digital™ PCR assays. Neither PCR assay confirmed the presence of target DNA from any of the 20 water samples, suggesting P. pectinata was not present in the vicinity of the collection sites during sampling. These results are inconclusive because they are based on a small number of samples collected at one timepoint. More comprehensive eDNA surveys are needed in the Chandeleur Islands to fully investigate their potential occurrence in these waters.

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