Lucas Griffin

Lucas Griffin is an assistant professor at the University of South Florida. In this interview, we discuss the use of acoustic monitoring to track the migration of Atlantic tarpon in support of management and conservation strategies for this iconic species.   

What research questions were you trying to answer with this project?

The Atlantic tarpon, also known as the silver king, is one of the most sought-after catch-and-release game fish in the United States. Before 2016, we knew little about this species—only that they aggregated in the Florida Keys each spring, and many moved northward to some extent afterward.  Growing concerns from anglers about their abundance led to questions we couldn’t answer. It became clear that we needed to address important knowledge gaps regarding their seasonal cycles, migratory patterns, and the threats they encounter along their migratory pathways. Led by Dr. Andy Danylchuk at the University of Massachusetts Amherst, this project aims to answer three main questions: What are the migratory patterns of Atlantic tarpon? When and where do Atlantic tarpon interact with potential threats? How can we use this data to improve management and conservation strategies? 

What was your most significant finding to date?

Using the collaborative tracking network facilitated by OTN, we confirmed that Atlantic tarpon is a highly migratory species! They can, sometimes, migrate thousands of kilometers, going from the tip of Florida all the way up to Louisiana, with our furthest detection recorded in Ocean City, Maryland. Atlantic tarpon displayed repeatability—meaning they traveled similar migratory routes every year and at around the same time—and encountered multiple threats, including anglers, sharks, and toxic human-driven algal blooms. Our tracking data also suggests multiple Atlantic tarpon sub-groups exist. One of these groups migrates along the eastern Gulf of Mexico, spanning from the Florida Keys to Louisiana. The second group primarily migrates along the Eastern U.S. Seaboard, spanning from the Florida Keys to the Chesapeake Bay. Thus, these two different groups necessitate different management and conservation strategies.  

What was the biggest challenge you faced during this project?

By far the most challenging part of this study was catching the fish. These fish, sometimes 70-kg or more, can only be caught using a hook and line. They have very bony mouths and love to jump, so it’s hard to bring them to the boat for tagging. For an angler, if you manage to hook even one, it’s a good day! We collaborated closely with anglers and fishing guides across the southeastern U.S. who would host us and assist with tagging tarpon.   

During the final day of a tagging trip in Tampa Bay in 2017, alongside my friend Capt. Court Douthit, striking out seemed inevitable for that last evening. Around 3:30 a.m., just hours before my flight back to the University of Massachusetts Amherst, we suddenly heard a handful of loud splashes in the darkness about 30 meters away—a clear sign of a hooked tarpon. We looked for another boat that might have hooked it, but there was only a young man in his early twenties on a bridge 15 meters above us. After some shouting back and forth, we managed to persuade the angler to let us try to land his jumping fish for research purposes. He agreed and we were able to tag and track the fish for five years!  

How does OTN support your projects? 

Without the collaborative effort of sharing detections that OTN facilitates, studying Atlantic tarpon would not have been possible. OTN, alongside other tracking networks—like FACT, ACT and iTAG—have been a cornerstone of our research efforts, enabling us to answer our research questions and contribute to the broader scientific community. OTN’s substantial loan of receivers for our work in the Florida Keys was also essential, especially after Hurricane Irma led to the disappearance of many of our receivers. Their expertise in quality control for our array was excellent and helped maintain data integrity throughout the project. Best yet, OTN helps foster collaborative efforts across institutions and partners.  

OTN has also been key to the success of other research projects, for example on giant trevally in Seychelles and diamondback terrapin in Massachusetts. In fact, we would not have been able to study diamondback terrapin without OTN’s loan of twelve receivers. I encourage all aquatic telemetry researchers to join OTN because they excel in data quality control, sharing detection information, providing equipment loans, analytical support, and fostering collaborations across numerous research groups. Moreover, the individuals behind OTN—both researchers and staff—go above and beyond to support research projects.