Sea Turtle Research

The Conservancy of Southwest Florida sea turtle program is one of the longest continuously running sea turtle monitoring research projects in the world.

Since the program’s inception, we have documented over 320,000 hatchlings from Keewaydin Island reaching Gulf of Mexico waters for their chance at becoming adults.

Female loggerhead sea turtle

what we do

Our work seeks to gain a better understanding of what these animals are doing in and out of the water, while protecting as many nests and hatchlings as possible.  The science team monitors sea turtle nesting activity, prevents nest predation by resident wildlife, and conducts cooperative research with agencies and universities to gain insight into the life history of sea turtles. Most of the turtles recorded on Keewaydin are loggerheads, although green turtle nests are periodically encountered. In 2015, we documented the first leatherback nest on Keewaydin. It was also the first leatherback nest ever recorded in Collier County.

During sea turtle nesting season, we patrol Keewaydin Island to locate nesting adults or their tracks so that we can cage the eggs to protect them from predators. We apply PIT tags, flipper tags, and measure the adult. In this manner, the adult sea turtle can be identified and its nesting history documented over the years.

Nesting female loggerhead sea turtle returning to the Gulf of Mexico
Nest excavation

Once each nest hatches, Conservancy scientists determine the hatching success and determine the fate of each nest such as whether it was washed out, flooded, depredated or successful. This information helps to determine the overall success of the nesting season on Keewaydin Island from year to year. This helps to track population trends overtime to see if the sea turtle population that nests on Keewaydin Island is increasing, decreasing or staying the same.

The nesting records of some the Keewaydin turtles now span well over 25 years. What is amazing is that baby sea turtles that we helped get to the Gulf of Mexico at the start of this project could now be returning as adults to lay their eggs.

Watch this episode of Experts and Insights to hear from longtime Conservancy Biologist Dave Addison on the history and success of the program

COLLABORATIVE SEA TURTLE RESEARCH PROJECTS

We conduct independent and cooperative research with various universities and Federal, State and County agencies to advance the overall knowledge about the life history of sea turtles.

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The east coast of Florida is mainly producing female sea turtles. Keewaydin Island’s hatchlings are a good mix or mostly males. It shows how important Keewaydin really is to the population of turtles.

- Jill Schmid, Rookery Bay National Estuarine Research Reserve and former Conservancy sea turtle intern.

The Conservancy has worked to protect over 320,000 hatchlings over the last 38 seasons.

Hatchling Sex Ratio Study

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In 2001, the Conservancy teamed up with Rookery Bay National Estuarine Research Reserve to determine the sex ratio of hatchlings on Keewaydin Island. The sex of a loggerhead sea turtle is usually determined by nest temperature during the middle third of the 55 day incubation period. Nest temperature can be affected by a number of factors including nest location and rainfall amount in a given year. There are typical temperature ranges the can be used to predict whether or not a nest will produce primarily males or females. Generally, the hotter the nest the more females, hence the saying “hot chicks and cool dudes.”

Data loggers are placed in a number of nests each year. These devices take temperature measurements inside the nest during the incubation period to help the teams determine the gender ratio of a given number of nests each year.
As ambient air temperatures rise we can expect nest temperatures to do the same, ultimately producing more females than males. Our research efforts on Keewaydin show us that the island produces a sizable portion of cooler, male dominated nests. Though we may not have as high a density of nests as many other beaches in Florida, these male producing beaches are critical to the survival of loggerhead sea turtles.
Loggerhead sea turtle hatchling
Green Sea Turtle (18)

If there are chances to help fellow researchers out, or provide a window into the lives of these animals, you just say yes. That’s how you develop a rapport with your colleagues.

- Dave Addison, Conservancy of Southwest Florida sea turtle biologist

It is expected that only 1 in 1,000 sea turtles survive to adulthood. A loggerhead sea turtle nest can contain anywhere from 20 to over 100 eggs, which equates to 1 hatchling out of 10 nests that will survive.

Biological Sampling

Collectiing Biopsy Sample For Brian Shamblin Keewaydin Is. Florida 2011

collecting tissue samples

With our ability to interact with nesting loggerheads, we have been able to provide graduate students and facility at many universities with tissue samples for population studies and foraging area assessment with stable isotope analysis.

Some of these cooperative efforts have been on-going for a long as 10 years.

satellite tagging

Conservancy biologists and University of Central Florida began a satellite tagging program in 2009. The objective was to determine if loggerheads return to the same foraging areas year after year just as they return to the same beach to nest. Additionally, since nesting females lay multiple nests during the same year, we wanted to determine where sea turtles that laid nests on Keewaydin Island went in between nesting sessions. We are also interested in identifying migratory pathways, as well as specific foraging areas that are of importance to loggerhead turtles during the years when they do not nest. Recently we have teamed up with Sanibel Captiva Conservation Foundation to extend our project to include green sea turtles on Keewaydin and Sanibel Islands and as of 2021 with FWC to retag some of our earlier satellite-tagged turtles to see if they return to the same foraging areas over a decade later. If you would like to see where the turtles migrated to, you can visit them at www.seaturtle.org.

Turtle with satellite tag swims out to the Gulf

LOGGERHEAD SEA TURTLE FACTS

How much do you know about loggerhead sea turtles? Scroll over each tile to learn more about these native Florida reptiles!

Scientific name

Caretta caretta

Length of an adult

3 feet

Weight of an adult

250 - 300 pounds

Lifespan

Greater than 50 years

Habitat

Widely distributed throughout temperate and tropical regions of the ocean. Here in Florida, sea turtles use our patch reef ecosystems, just like you can see in our 5,000 gallon Patch Reef Aquarium, as foraging grounds.

Diet

Loggerhead sea turtles are primarily carnivorous eating items such as crustaceans, mollusks, jellyfish, fish and occasionally seagrass and algae.

Protection Status

Threatened in Florida, Endangered in other parts of the world.

Threats

As hatchlings, sea turtles face many natural predators, but as adults their only predators are sharks and humans. Human threats include habitat loss, poaching, pollution, litter (such as plastic bags), commercial fishing, and boat collisions.

How you can help

Clean up our beaches, use reusable bags instead of plastic bags, support fisheries that use turtle safe devices on their nets, and slow-down in designated channel zones.