The leatherback sea turtle is the largest of the five species that have been found in the northern Gulf of Mexico. With a carapace (top shell) length between 6-7 feet and weighing between 800-1000 pounds it is truly a magnificent creature. Any encounter with them is amazing.
Most encounters occur with fishermen or divers who are out searching for artificial reefs to fish or dive. Though very rare, they have been known to nest in this area. They feed exclusively on jellyfish and will follow them close to shore if need be. But what do leatherbacks do with most of their time? Do they hang offshore and follow jellyfish in? Do they circle the entire Gulf of Mexico and we see them as they pass? Based on past studies, many encounters with this turtle occur in the warmer months. They often become entangled in commercial fishing longlines set in the central Gulf of Mexico. But what do they do during the fall and winter? One of the tagging projects presented at a recent workshop tried to answer that question.
The project was led by Dr. Christopher Sasso of the National Oceanic and Atmospheric Administration. The tag chosen for this was a satellite tag. Since the leatherback must surface to breath air, and often is found near the surface following jellyfish, orbiting satellites would be able to follow them. As we mentioned in Part 1, catching the creature is step 1, and catching a six-foot 1000-pound sea turtle is no easy task.
The team used a spotter aircraft to locate the turtles. Once found, the pilot would radio the chase boat who would zip in with a large net. The net was connected to a large metal hoop and was designed to give way once it was around the turtle. Once in the net the turtle was hauled onto a small inflatable boat where the work of tagging could be done. They would measure the animal, take blood samples, place a PIT tag within them (similar to a microchip in your pet) and then attach the satellite tag by a tether to the tail end of the turtle before releasing it. The entire operation took less than 30 minutes.
Between 2015-2019 19 leatherbacks were tagged in the northern Gulf. 17 of these were females and 2 were males. Data obtained from these tags ranged between 63 and 247 days at liberty. The behavior the team noticed was divided into foraging behavior (feeding on jellyfish) and transiting behavior (direct swimming ignoring all).
The turtles foraged in this part of the Gulf until the fall season. At that point most of them moved south along the Florida shelf, past the western peninsula of the state, heading towards the Keys. A few chose to swim directly south against the Loop Current, and a small number remained in the area.
Those moving along the Florida shelf appeared to be foraging as they went. Those crossing the open Gulf may have foraged some but seemed to be focused on getting south to the nesting beaches. Almost all of the turtles entered the Caribbean on the east side of the Yucatan channel, following the currents, with their final destination being their nesting beaches. When they returned, they did so in the warmer months and used the western side of the channel – again following the currents – until they once again reached the northern Gulf and foraging began again. One interesting note from this study, the two males tagged did not leave the Gulf.
The tagging studies do show that leatherbacks use the Gulf of Mexico year-round. They usually head south to the Caribbean when it gets colder and use the currents to do so. It is during the warmer months we are most likely to see them here foraging on jellyfish. It is an amazing experience to encounter one of these large turtles. I hope you get to experience it one day.
Satellite tracks of leatherback movement in the GoM. Red (2015), Blue (2018), Black (2019).
Image: Sasso (et.al.) 2021.
Reference
Sasso, C.R., Richards, P.M., Benson, S.R., Judge, M., Putman, N.F., Snodgrass, D., Stacy, B.A. 2021. Leatherback Sea Turtles in the Eastern Gulf of Mexico: Foraging and Migration Behavior During the Autumn and Winter. Frontiers in Marine Science., Vol. 8., https://doi.org/10.3389/fmars.2021.660798.
Recently I attended a workshop on wildlife tagging projects. Researchers from across the Gulf of Mexico who had projects going on in the northern Gulf were invited to present their updates. I was there to help present what we have learned about diamondback terrapins but there were numerous other talks, and the results were fascinating. Fascinating enough that I thought the public would be interested in them as well. Most of the presentations were on fish or reptiles, but the fish included interesting species such as whale sharks, tiger sharks, cobia, and tarpon. So, I am going to run a series of posts on the different species along with another series on barrier island wildlife.
I thought I would start with an introduction on the methods of wildlife tagging and why scientists tag animals. Some of the reasons may seem obvious, but with today’s modern tags, there is a lot of information scientists can gain from doing this.
Why do they tag?
With the types of tags they used when I was in school there were a few things that you could learn. (1) How far do the animals range, (2) how fast they reached those locations, (3) some idea of live longevity – you at least knew how long they were “at freedom”. With these data you could get a better idea of what their habitat range was and how they used the habitat. Some, like blue sharks, may move great distances all year long. Others, like nurse sharks, may not move more than a few miles from the point where they were tagged. Others may move seasonally, spending summer in one region and winter in another. All of these data are useful to resource managers responsible for maintaining the species population.
With the more modern electronic tags, they can learn such things as how deep they dive, how long they stay at depth, what water temperatures they may frequent, what salinity they prefer, and let you know where the animal is at any given moment in time. Today’s tags are pretty amazing.
This tag is similar to the ones we used in the 1980s on sharks. They provide a number for individual identification. Ours also had a capsule with a note on water resistant paper.
Photo: Hallprint.
How do they tag?
Well… step one to answering this question is HOW DO YOU CATCH THE ANIMAL? – not as easy as you think. Whale sharks and leatherback sea turtles are quite a handful. If your target species is something like a white shark, tiger shark, diamondback rattlesnake, there is an extra danger added. As you plan a method for your safety, you must also plan a method for their safety. The objective is not harm or kill the creature – you will learn nothing from this. When I began my career, I saw a program on how they tagged polar bears in the 1980s. They would fly over the ice in a helicopter looking for the bears. When the bears saw the helicopter, they would run for the safety of water. The scientist would try to shoot a dart into the animal to put it asleep long enough to get a tag on it. BUT if you overdosed the bear, and it made it to the water, it could drown. So, from the air, they had to gauge the weight of the bear, guess what amount of the drug to shoot, and hope they were right. If the bear did fall asleep, how “asleep was it? Did you give ENOUGH drug? Polar bears can be very dangerous. In the episode I watched the bear was asleep, but the researchers did mention that they will “play sleep” and you need to be ready. Such was the world of wildlife tagging 40 years ago.
One of the things that was also discussed when I was in school was what type of tag you were going to place on the animal. They did not have the neat tools they have now. Most tags had a capsule with a piece of paper, sometimes written in multiple languages, to call said person and report where and when they found the animal. There was usually a monetary award for doing so, or sometimes a hat or T-shirt. I remember the hat you got for reporting a tagged redfish was really neat, but I never caught a tagged one.
You did not want to place a tag that would alter the natural behavior of the animal. In the case of the polar bear, they would place an ear tag and paint a large number on its side in black paint. This made sense from the biologist’s side – flying over the ice you could see the large black “3” on a bear and know the individual. But that large black number could also be seen by their prey. Not good. I saw researchers painting the shells of gopher tortoises with all sorts of neon colors to make detection by them easier, but easier for their predators as well.
Radio tagging was used 40 years ago. This involves capturing the animal (as we have already seen – fun in itself), putting it asleep and attaching/inserting a radio tag. This tag provides a radio signal that can be detected by a receiver carried by the research holding an antenna walking/driving around following the animal. You had to be within range to hear the signal and – honestly – good at detecting the signal. Some researchers were better at this than others. As you can imagine this was only as good as your ability to keep up with the animal. At some point your car/boat would need fuel, or the animal crossed a river you could not. It provided some good data, but there were limits.
Today modern tags have solved a lot of these issues. Some new tags do not have typed notes but sensors that can detect the elevation/depth, temperature/salinity, all sorts of information that was unknown in my college days. These tags can be retrieved and downloaded on a computer to give a much better idea of how the animal spends its time and what it seeks.
This modern shark tag could provide additional information such as diving depth, water temperature, and more.
Satellite tags work well for creatures who surface frequently – sea turtles, whales, whale sharks. Satellites can detect them, and you can follow their movements/habitat preferences as they are actually using them.
For species at depth, like some sharks, cobia, tarpon, etc. there are now acoustic tags. The tag emits a signal that is detected by an array of receivers the researchers place in the environment. As the animal passes within range of the receiver it is detected, and the downloaded data gives a similar picture of how the animal uses the environment. A couple of neat things about acoustic tags are that (a) you can track satellite tagged animals while they are diving, and (b) your receivers can detect other species tagged by other researchers and let them know where their creature was. This was one reason for the workshop – so, everyone could meet everyone else and know who has tagged what and how to share information.
No tag is permanent. All are designed to fall off. Battery power will eventually fail. But no animal is stuck with this all of their lives as they could have been when I was in school. In future articles we will look at the results of some of these studies.
This tag with an antenna can be detected by a satellite and tracked real time.
Photo: USGS
Mark Twain once said – “Everyone talks about the weather, but no one does anything about it.” A similar statement could be made about the Gulf Sturgeon – “Everyone talks about the Gulf sturgeon, but on one has actually seen one.” Those along the coast who have a dock, pier, seawall, or have placed a marina, artificial reef, or oyster farm over state submerged lands, have certainly heard about this fish. It is a portion of the permit in each case. Heck, maybe they have seen one. But it is a fish that many know about but seems elusive to encounter.
Left-facing Gulf sturgeon illustration. Lighter brown than Atlantic sturgeon. Credit: Jack Hornady for NOAA Fisheries.
The Gulf sturgeon (Acipenser oxyrinchis desotoi) is one of 27 species of sturgeon found worldwide. It is a subspecies of the Atlantic sturgeon. These are ancient fish, and they look it. Sturgeons are large, reaching lengths of up to eight feet and 300 pounds. They have armored looking scutes embedded into their skin, giving them a “dinosaur” appearance. They have a heterocercal caudal fin that resembles a shark. And like sharks, they have a cartilaginous skeleton and a spiral valve within their digestive tract. Their head has a pointed snout with whisker-like structures called barbels, which are used for detecting food buried in the sand, and they lack teeth. They have been swimming in our oceans since the era of the dinosaurs, about 225 million years.
Sturgeons are anadromous fish, meaning they (like salmon) spend their adult lives in salt water, traveling miles upriver to their location of their birth to lay eggs. The Gulf sturgeon spends the colder months (November through February) inhabiting our bays and the nearshore Gulf of Mexico in waters less than 100 feet. Now is the time when you may encounter one near the coast. Because they eat very little while in the river systems, they gorge on benthic invertebrates during the winter. They spend most of their time over sand flats and sand bars, using their barbels to detect a variety of buried invertebrates. When sturgeon sense warmer months coming, they begin their long migrations up the inland rivers seeking the area where they were born. At this time, they leap from the water like mullet and make splashes that can be heard from a long distance. They are famous for this in the Suwannee River and have, at times, been a concern for boaters and jet skiers. Many boaters have had to go to the hospital due to collisions with leaping sturgeon.
The Gulf Sturgeon.
Photo: U.S. Geological Survey
Once they reach the spawning grounds, if conditions are right – temperature, water flow, and pH – the female will lay between 250,000 – 1,000,000 eggs which will become fertilized by the smaller males. Most eggs will not survive, but for those that do, the cycle will begin again with the trek back towards the Gulf of Mexico beginning in September.
Why are they declining?
Early in the 20th century they were sought after for their meat and fertilized eggs (caviar). Most of the rivers within their range (which is between the Mississippi and Suwannee Rivers) have been damned, dredged, or both. Dams impede their ability to reach their nursery grounds and dredging can reduce the required conditions to stimulate breeding, or literally bury their eggs. Between these human activities, their numbers declined drastically. In 1991 they were listed both as a federally and state threatened species and have been protected and monitored ever since. The best population, and best chance to encounter one, is in the Suwannee River. This river has been left basically pristine and has not had the habitat altering activities of the others. Locally, they are found in the Escambia, Blackwater, and Yellow Rivers.
Winter is the time to see them in the lower parts of our bay. Maybe you will be lucky enough to encounter one.
References
The Gulf Sturgeon. Florida Fish and Wildlife Conservation Commission.
Diamondback terrapins are the only resident turtle within brackish water and estuarine systems. Their range extends from Massachusetts to Texas but, prior to 2005, their existence in the Florida panhandle was undocumented. The Panhandle Terrapin Project was developed to first determine whether terrapins exist in the panhandle (Phase I) and, if so, what is their status (Phase II and III).
The project began at the Marine Science Academy at Washington High School (in Pensacola) in 2005. Between 2005 and 2010 the team was able to verify at least one record in each of the panhandle counties. For Phase II we used what we called the “Mann Method” to determine the relative abundance of terrapins in each area. To do this we needed to conduct assessments of nesting activity in each county. In 2012 the project moved from Washington High School to Florida Sea Grant. At that time, we developed a citizen science program to conduct Phase II of this project. Effort first focused on Escambia and Santa Rosa counties, but in recent years has included Okaloosa County. Florida Sea Grant now partners with the U.S. Geological Survey (based out of Gulf County) to assist with Phase II and lead Phase III, which is estimating populations using mark-recapture methods, as well as satellite tagging to better understand movements and habitat use. The focus of Phase III has been Gulf County, but tagging has occurred in Okaloosa and Escambia counties.
Over the years we have trained 271 volunteers who have conducted thousands of hours of nesting surveys and helped obtain a better picture of the status of diamondback terrapins in the Florida panhandle. Here are the 2023 project results.
Results from 2023
We trained 67 volunteers; 35 (52%) of which participated in at least one nesting survey.
The volunteers conducted 196 surveys logging 212 hours.
During those surveys terrapins (or terrapin sign) were encountered 43 times; a Frequency of Encounter (FOE) of 22%.
Three terrapins were tagged. Two from Okaloosa and one from Escambia. All but two of the nine primary survey beaches saw nesting activity (78%). One new nesting beach was discovered.
Escambia County
Two nesting beaches. 47 surveys. 7 encounters (FOE = 15%).
The Mann Method assumes the sex ratio is 1:1 (male: female) but recent studies suggest the ratio may be as high as 5:1 (male: female). Based on these two rations the number of terrapins estimated to be using these beaches ranged from 4-36.
One terrapin (“Dollie”) was tagged. Fire ants and torpedo grass were reported on some beaches.
Santa RosaCounty
Three nesting beaches. 68 Surveys. 14 encounters (FOE = 21%).
The number of terrapins estimated to be using these beaches ranged from 6-30.
No terrapins were captured, though one was seen nesting. No invasive species were reported from the nesting beaches.
OkaloosaCounty
Four nesting beaches. 67 surveys. 21 encounters (FOE = 31%).
The number of terrapins estimated to be using these beaches ranged from 2-66.
Two terrapins were tagged (“Kennedy” and “Molly”). Phragmites were reported from all beaches.
Walton County
Walton county currently does not have a volunteer coordinator and surveys are not occurring at this time. We are working with an individual who may take the lead on this.
BayCounty
This team is just beginning and currently there are no primary beaches. The team focused on five beaches encountering terrapin nesting activity on one of them. They conducted a total of 14 surveys encountering terrapin tracks on 1 of those (FOE = 7%). The estimated number of terrapins using this beach ranged from 4-12.
Baldwin County Alabama
Due to the proximity of terrapin habitat and nesting beaches at the Alabama/Florida line, and the possibility of terrapins using habitat in both states, a team was developed in Baldwin County Alabama this year. The team began conducting Phase I surveys and encountered one deceased terrapin. No nesting beaches have been identified at this time.
Summary
The results of this year’s surveys suggest that, based on the number of nesting beaches we know of, there are anywhere from 2-66 terrapins utilizing them. Again, two of the primary beaches did not have nesting activity this year. USGS tagging studies will provide better population estimates and a better understanding of how these animals are utilizing these habitats. The current population estimate for Gulf County is a little over 1000 individuals and most are showing relatively small range of habitat utilization, although two individuals in the western panhandle moved from one county to the neighboring one.
Training for volunteers occurs in March of each year. If you are interested in participating, contact Rick O’Connor – roc1@ufl.edu.
Despite efforts by public and private land managers, feral hog populations continue to rise in many areas in Florida. Feral hogs damage crop fields, lawns, wetlands, and forests. They can negatively impact native species of plants and animals. Their rooting leads to erosion and decreased water quality. Feral swine can also harbor and infect domestic swine with diseases such as African Swine Fever, foot-and-mouth disease, pseudorabies, swine brucellosis, and others.
USDA APHIS conducts feral swine monitoring for diseases to help safeguard our pork production here in the US. More than 6,000 samples are taken annually to test for diseases of concern. This monitoring effort not only keeps our domestic swine safe but also keeps humans safe from diseases that can infect us. African Swine Fever (ASF) is the main disease of concern right now for the state of Florida, especially those counties bordering the Gulf of Mexico.
ASF is a deadly disease of both feral and domestic hogs. It is not transmitted to humans so it is not a health or food safety concern. It is, however, highly contagious and would likely have a catastrophic effect on our domestic pork industry. Although it has not been found in the US, this disease has recently been detected in the Dominican Republic and Haiti.
This concern has led to a new monitoring program in Florida specifically for ASF in counties bordering the Gulf. USDA APHIS will begin trapping wild hogs in these counties in order to monitor populations for ASF. Landowners, both public and private, can benefit from this monitoring program. Professional trappers will be employed to remove wild hogs for this monitoring effort. For more information on this program, contact Buddy Welch, North Florida Assistant District Supervisor, USDA Wildlife Services, ASF Surveillance at edgar.welch@usda.gov.
Sounder of hogs in a corral trap. Photo Credit: Jennifer Bearden
A deer darting across a path, a bobwhite calling at sunrise, or the tracks of a coyote in the mud are all fascinating examples of how we enjoy our natural areas. Have you ever wished you could watch wildlife all day to understand the intricate relationships they have with one another? What if you could learn more about their behavior? And their habitat and daily activities?
Deer captured on a digital game camera.
Image: Dr. Carolina Barzzui.
Dr. Carolina Baruzzi at the UF/IFAS North Florida Research and Education Center and Dr. Corey Callaghan at the UF/IFAS Fort Lauderdale Research and Education Center are launching “ConservationCam”, a new extension program to help you monitor wildlife on your property using camera traps.
Camera traps are a valuable tool for wildlife monitoring. When an animal moves in front of a camera, they trigger a motion sensor to take a picture or video. Camera traps can be set up in multiple ways to target a species or habitat of interest, such as a forest opening or a wildlife burrow. Thanks to their versatility and relative low cost, camera traps are being used in a variety of contexts, for example, understanding the effects of wildlife or habitat management on target species.
Images of turkeys captured on a digital game cam.
Image: Dr. Carolina Barzzui.
The primary goal of ConservationCam is to provide private landowners with access to camera traps, and expert guidance about monitoring wildlife and managing natural resources for biodiversity based on camera trap observations. Armed with this knowledge, landowners can make informed decisions about land management practices that positively impact biodiversity on their property. If you live in the Florida Panhandle, and are interested in using camera traps to monitor wildlife on your property, while learning how to answer different ecological questions, we are gathering expressions of interest through this online form.
Rabbit near a burrow on a digital game came.
Image: Dr. Carolina Barzzui.
