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christian-binoculars

Using the rangefinder to take vessel locations.

by Christian Gredzens (PhD Candidate/Research Assistant)

The Big Bend of Florida serves as important habitat for a wide variety of marine species, including three species of marine turtles: loggerheads, Kemp’s ridleys, and green turtles which are all listed under the Endangered Species Act. Specifically, the coastal seagrass beds in the region act as important foraging and developmental habitat for these species of turtles. This area also supports major recreational opportunities such as the Florida bay scallop fishery which brings thousands of people out onto the water from Bay to Hernando county between late June and late September annually. Coincidentally, the primary scalloping grounds overlap with the seagrass beds turtles use. Unfortunately, the effects of increased human use on turtle foraging patterns is unknown and it is thought that high densities of people out on the water may displace turtles from their foraging grounds into less productive habitats.

gredzens-turtle-satellite

Attaching a satellite transmitter to a small green turtle. Photo taken with all applicable state and federal permits in place.

Fieldwork began in May 2016 where I attached ten satellite transmitters to two species of turtles: Kemp’s and greens. The transmitters will allow me to figure out how turtles are moving in the environment and also help me determine if there was a change in movement after the scallop season opener in late June. Next, I began assessing human use of the area with countless hours spent on the water with my volunteers getting vessel locations using a handheld rangefinder. To date over 3,600 boat locations have been collected along 12 miles of coast with over 3,000 of them counted during the scallop season alone. At the same time I have been assessing the different habitats in the area to see if certain areas provide higher quality habitat. Finally, I have been opportunistically catching turtles from the side of the boat to get a better idea of the specifics for each turtle population in the area.

gredzens-turtle

Capturing a male loggerhead in Crystal River. Photo taken with all applicable state and federal permits in place.

The next phase of the project is to create a habitat map to overlay with turtle sightings and tracking data which will tell me if there are specific habitat associations for each species. I will also look at if there are any effects from the scallop season on turtles by looking at movements before and during the scallop season and matching them with boat locations and high density scalloping areas. Hopefully this information can be used to inform and educate the public on marine turtles in areas where they recreate.