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USM Biology Professor Uses Environmental DNA to Verify Smalltooth Sawfish in Mississippi Waters

Thu, 07/18/2019 - 13:19pm | By: Van Arnold

Dr. Nicole Phillips, assistant professor of biology in The University of Southern Mississippi (USM) School of Biological, Environmental, and Earth Sciences, and vice president of the Sawfish Conservation Society, has verified the presence of smalltooth sawfish in Mississippi waters using environmental DNA (eDNA) with the assistance of USM graduate student Ryan Lehman. This research is supported by the state of Mississippi with funding from the National Institutes of General Medical Sciences of the National Institutes of Health (NIH).

Sawfish are a type of ray, but they have a long nose surrounded by teeth, which inspired their name. Five sawfish species are recognized, and they are all Endangered or Critically Endangered. Dr. Phillips explained that most sawfish species are found in Australia, except for what is presumed to be the last viable population of smalltooth sawfish near the southwest coast of Florida; however, in 2014, a smalltooth sawfish was caught near Deer Island off the coast of Mississippi. Since then, there have been several more reports of juvenile sawfish in Mississippi and Louisiana, and Dr. Phillips noted that their presence may indicate sawfish are giving birth in Mississippi waters.

According to Dr. Phillips, the traditional way to study marine species was to put out nets and hope to catch a specimen. This method requires permits, can put undue stress on the animal, and unlikely to be successful in the case of rare and Critically Endangered species. Therefore, she created an eDNA analysis system to find smalltooth sawfish without capturing them. She collects water samples and tests them to detect smalltooth sawfish eDNA, or DNA left behind by the sawfish. Dr. Phillips has used this method in collaboration with Dr. Gregg Poulakis and other colleagues from the Florida Fish and Wildlife Conservation Commission in Charlotte Harbor, Florida.

With the help of Jill Hendon, director of the USM Shark Research Program and the interim director of the Center for Fisheries Research and Development at The USM Gulf Coast Research Laboratory (GCRL), Phillips and Lehman collected samples of water from Cat Island, Ship Island, and the Deer Island area, and they tested the water using eDNA analysis. Over the course of three different months, the water sample results came back positive for smalltooth sawfish eDNA, confirming their presence in Mississippi. Dr. Phillips noted that these results are promising, and they will keep testing water samples to determine whether they can replicate the positive results.

Moving forward, Dr. Phillips plans to use habitat modeling to identify habitats that could be suitable for juvenile smalltooth sawfish and focus sampling on these areas. She also hopes to test other sites such as the Pascagoula River in Mississippi and the Chandeleur Islands in Louisiana, where sawfish encounters have been recently reported.

Treating habitats with respect and practicing responsible fishing can help protect the smalltooth sawfish, but the most important way to help is to report any current or past sawfish sightings. If you catch a sawfish, make sure to cut the line, leave the sawfish in the water, and report your sighting by calling the Sawfish Hotline 1.844.4SAWFISH (1.844.472.9347). Any information can potentially provide Dr. Phillips with important data to help map where smalltooth sawfish can be found in Mississippi.

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