Tagging Wildlife Part 2 – Leatherback Sea Turtles

Tagging Wildlife Part 2 – Leatherback Sea Turtles

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.

Local Oysters Displaying “Green Gills” 

Local Oysters Displaying “Green Gills” 

And it’s a good thing! Green gill oysters are prized in the oyster community. In the Carolinas and Northern France, green gill oysters are a seasonal, cherished crop and a product of the saying “You are what you eat!” The phytoplankton, Haslea ostrearia, is the typical culprit, and their distribution is measured by direct observation from plankton tows or the occurrence of green-gilled oysters. The exact distribution is unknown, but there are reports of H. ostrearia throughout the Atlantic, Pacific, and Indian oceans. Haslea ostrearia is a beautiful pennate diatom that contains a water-soluble blue pigment known as marennine (More Here). Marennine’s production is stimulated by long photoperiods, blue light, and high light/low cloud weather. It can also be released into the water and into the flesh of organisms (typically oysters) that consume them.

Green-gill oyster on the farm
Fresh out of the water Grayson Bay Oyster with green gills! – Brandon Smith, Grayson Bay Oyster Company

Pensacola Bay, and surrounding areas, had a pretty mild fall in terms of rainfall, and the bays have turned a beautiful green-blue hue as the bays have risen in salinity and phytoplankton typically found in the Gulf of Mexico were able to survive. Brandon Smith, owner of Grayson Bay Oyster Company, was out working his farm January 7th, 2024, and sent a text to me saying “take note of the green gills,” and I was very shocked and happy to see actual, green-gilled oysters in our local waterways. He graciously harvested a few dozen to examine (and let me taste test), and I was able to confirm the presence of green gills in the oysters. After further research on H. ostrearia, it seems as though the pennate diatom made it into our bays and is the culprit of this wonderful surprise.

Oyster displaying green-gills
A local Grayson Bay Oyster displaying green-gills – Thomas Derbes II

When I shucked my graciously donated oysters from Grayson Bay, I was reminiscing on the first time I came across green-gilled oysters. The first batch of green gill oysters I ate came from an oyster farm in North Carolina called N. Sea Oyster Company. Their green-gilled beauties “Divine Pines” were requested by a wedding I was catering for, and I was able to slurp down one to get talking and tasting notes. The seasonal Divine Pines offered a sweet yet salty taste and became one of my favorite out-of-area oysters to serve at events and to personally consume. While beautiful, the green-gilled oysters are usually only found in the fall/winter months. These green-gilled Grayson Bays were very comparable and offered a salty yet very sweet and minerally finish. The H. ostrearia is responsible for not only the green gills, but the sweet tasting notes, and I highly recommend adding any green-gilled oyster to your fall/winter raw bar selection.   

References:

Turpin, Vincent & Robert, J-M & Philippe, Goulletquer & Massé, Guillaume & Rosa, Philippe. (2008). Oyster greening by outdoor mass culture of the diatom Haslea ostrearia Simonsen in enriched seawater. Aquaculture Research. 32. 801 – 809.

From Seed to Shuck – More Oyster 101

From Seed to Shuck – More Oyster 101

When you hear about oyster farming, you typically hear the word “seed” and how it is highly important to the future of the farm. While it might not be a typical seed that produces agricultural crops like corn, this seed is a living, breathing (albeit in the water) organism that produces a beautiful, cupped oyster. Depending on market size demand and requirements, it could take anywhere from 8 to 24 months to reach “shucking ready” size. Let’s take a dive into the timeline of an oyster, from seed to shuck.

Cooler Full of Seed Headed To Farm
A cooler full of R6 oyster seed headed out to the farm – Grayson Bay Oyster Company

Oyster farmers typically buy seed from an oyster nursery or hatchery, where they carefully spawn male and female oysters together in individual spawning chambers. Depending on the farmer’s needs, they can produce either diploid or triploid oyster larvae (more on triploids next week). These larvae are free-swimming for the first 2-3 weeks of their life until they develop into pediveligers (Oyster 101). Hatcheries will, for lack of better terms, mix the pediveligers with very tiny grains of ground-up oyster shells. These pediveligers will then attach to a single grain and begin to form into a “seed” oyster. Seed costs range and vary from year to year, and this cost is usually one of the biggest financial purchases oyster farmers can make. Seed is sold by size, starting at 6 millimeters (typically called size R6), and by increments of 1,000. Hatcheries and nurseries are located all along the Gulf Coast, but Florida law requires seed put in the Gulf of Mexico waters and estuaries must come from Gulf of Mexico hatcheries, and the same rules apply to Atlantic waters.

Oyster Seed
Oyster Seed (>R16) – Thomas Derbes II

Once purchased, these seed oysters make it to their homes in beautiful nutrient-rich waters and grow at a steady rate, and can reach an overall size of 2 inches in 4 to 9 months. During those months, the seed are filtering gallons of water per oyster per day, helping sequester carbon in their shells and consuming large amounts of plankton and algae that could contribute to the eutrophication of the bays. Oyster farmers will check on the seed almost weekly, changing bag mesh sizes and sorting the seed by size. Farmers will also take this opportunity to check for any oyster predators and swiftly evict them from their all-you-can-eat buffet. Sorting is done by using a “tumbler” that has a long drum with holes of varying sizes. This tumbler also helps clean the oyster and chip away at the lip of an oyster shell, causing the oyster to grow deeper and create a beautiful cup.

Farmed oysters do not have a size limit, but most farmers stick to a 2.5 to 3-inch size oyster. These oysters have filtered over 7,000 gallons of estuary water individually and sequestered a very generous amount of carbon, in the form of calcium carbonite (more here), in their shells in their first year of life. Once deemed ready for harvest, farmers will pull them out of the water and get them quickly in the fridge, following strict biosecurity guidelines and regulations to provide a safe product year-round.

Oysters of varying size
Some oysters are fast growers! These were apart of the same spawn. – Thomas Derbes II

And there you have it, from seed to shuck. With the holidays coming up, and seafood sometimes being a part of the holiday plans, reach out to the local oyster farmers in your area to reserve a dozen or two for your favorite uncle. You can also wow the crowd with this very fancy mignonette recipe below! 

Lemon Champagne Mignonette

Juice From 2 Local Meyer Lemons (They’re in Season!)

1 Shallot Chopped Finely

½ cup Champagne Vinegar

¼ cup Red Vinegar

1 tbsp each of Green and Pink Peppercorns 

24 Local Farm Raised Oysters (For the Environment!) 

1.       In a bowl, add the juice of Meyer lemons and shallots. Let it marinate for 10 minutes.

2.       Add champagne vinegar, red vinegar, and peppercorns to the lemons and shallots.

3.       Chill for at least 30 minutes in the fridge.

4.       Shuck oysters and top with freshly made mignonette. Enjoy!

The Elusive Gulf Sturgeon

The Elusive Gulf Sturgeon

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.

https://myfwc.com/wildlifehabitats/profiles/saltwater/gulf-sturgeon/#:~:text=The%20Gulf%20sturgeon%2C%20also%20known,as%20a%20source%20of%20caviar.

The Gulf Sturgeon. National Oceanic and Atmospheric Administration.

https://www.fisheries.noaa.gov/species/gulf-sturgeon.

October Seafood – Flounder

October Seafood – Flounder

For many who grew up in the Pensacola area October meant flounder gigging season.  This once popular past time involved going out at night along the shores of Santa Rosa Sound with flounder lights and gigs seeking a local favorite flounder.  Everyone has their favorite recipe for this fish but in this article, we are going to focus on the fish – maybe something you did not know about it. 

In the northern Gulf of Mexico, flounder are flatfish with the two eyes on the left side of the head.  Locally, flatfish with eyes on the right side are called soles.  We do have native soles, but all species are too small to be a food option.  If you are not familiar with the “two eyes on one side of the head” idea, yes – flounder hatch from the egg looking like a normal fish, an eye on each side of the head.  But earlier in development one eye slides across to the other side.  This is a weird transformation and there are probably videos online, so you see how this happens – check them out.  The reason for this transformation is to improve depth perception.  Eyes close together give the animal binocular vision.  Binocular vision does not have a wide viewing range, can basically see what is in front of it but not so much what is behind it, but it does give the animal good depth perception, it can tell how far away the prey actually is, and this is important when hunting. 

Once the eyes have shifted to the left side of the head, flounders lose the pigments on the side without eyes, which becomes white, and the fish lays on its side – white side down.  The cells on the “eye side” have chromatophores that allow the fish to change color to match the sand on the bottom.  Another important feature of being a successful hunter.  Most of know they will bury themselves in this sand as well.  With their binocular vision, camouflaged body, and sharp teeth, they lie in wait to ambush predators. 

You may also be surprised at how many different kinds of flounder are found in the northern Gulf of Mexico.  There are 21 species listed, and they range in size from the small Spiny Flounder which can reach an average length of 3 inches, to the Southern Flounder which attains a length of 3 feet.  The Gulf flounder and Southern flounder are two species that are popular seafood targets, but any decent sized flounder will do. 

Flounder are found in a variety of habitats ranging from shallow seagrass beds nearshore, near structure just offshore, to artificial reefs and the base of bridges, to depths of 1200 feet in the Gulf of Mexico.  Many species spend the warmer months in the estuaries moving offshore when the weather cools down to spawn.  Hard northerners can trigger a mass migration and a great time for commercial and recreational fishermen alike.    

It is flounder season.  Whether you prefer to catch your own or buy from the local seafood market I think will enjoy one of the variety of ways to prepare this fish. 

A flounder scurrying across the seafoor. Photo: NOAA
The Great Scallop Search; Pensacola Bay 2023

The Great Scallop Search; Pensacola Bay 2023

Introduction

Bay scallops (Argopecten irradians) have been an important part of the economy of many gulf coast communities within the Florida Big Bend for decades.  It was once abundant in all gulf coast counties of the state but beginning in the 1960s populations in many bays began to decline to levels where they are all but nonexistent.  The cause of this decline has been associated with many factors including a decline in water quality, a decline in suitable habitat (sea turtle grass beds – Thalassia), and overharvesting.  Most likely the cause included all of these.  Since the collapse of both the commercial and recreational fishery, Gulf coast communities have been trying to address all three of the stressors above.  Multiple monitoring projects are ongoing in the Pensacola Bay area and one of those is the Great Scallop Search.  

The Great Scallop Search was developed by Sea Grant Agents in Southwest Florida and expanded, through Florida Sea Grant, to Northwest Florida.  In each location volunteers snorkel a 50-meter transect line searching for live bay scallops, as well as monitoring the status of the seagrass habitat.  Since 2015 317 volunteers have logged 634 hours surveying 407 50-meter transects in 106 grids in Big Lagoon or Santa Rosa Sound.  In that time 4 live scallops have been logged, though we hear anecdotal reports of additional scallops being found in these bodies of water. 

Survey Method

Volunteers select and survey one of 11 grids in Big Lagoon, or one of 55 grids in Santa Rosa Sound.  Once on site, the volunteers anchor and record preliminary information on the data sheet provided.  Two snorkelers enter the water and swim on opposite sides of a 50-meter transect line searching for live scallops.  Any live scallop found is measured and returned.  The species and density of the seagrass is recorded as well as the presence/absence of macroalgae on that seagrass.  Four such transects are surveyed in each grid. 

2023 Results

2023SRSBLTotalOther
# of volunteers    72No significant difference between 2022 and 2023
# of grids surveyed8816Slight decrease from 2022.  16 of the 66 grids (24%) were surveyed. 
# of transects surveyed265177A decrease from 2022.  More surveys were conducted in Big Lagoon than Santa Rosa Sound. 
Area surveyed (m2)2600510077001.9 acres
# of scallop found2  24Four live scallops are a record for this project.  It equals the sum of all other live scallops since the project began. 
Scallop Size (cm)4.5, 5.04.0, 4.5  
Surveys with Seagrass    
Halodule5121717/21 surveys – 81%
Thalassia8111919/21 surveys – 90%
Syringodium0222/21 surveys – 10%
Grass Density    
100% grass391212/21 surveys (57%) were 100% grass
90%101Note: Volunteers typically select area for transects
75%314with a lot of grass.
70%101 
50%3912 
5%101 
Macroalgae    
Present448 
Absent2101212/21 surveys (57%) had no macroalgae.
Abundant224 
Sediment Type    
Mud011 
Sand781515/21 surveys (71%) were sandy.
Mixed145 

21 surveys were conducted covering 16 grids.  8 grids were surveyed in each body of water. 

A total of 77 transects were conducted covering 7,700 m2 and four live scallops were found. 

Two of the scallops were found in Big Lagoon and two in Santa Rosa Sound. 

All scallops measured between 4-5cm (1.6-2”). 

The number of live scallops found this year equaled the total number found over the last eight years. 

Most of the transects included a mix of Halodule and Thalassia seagrass ranging from 100% coverage to 5%.  The majority of the transects were between 50-100% grass.  Four transects had 100% Thalassia.  Three of those were in Santa Rosa Sound, one was in Big Lagoon.  The diving depth of the volunteers ranged from 0 meters (0 feet) to 2.4 meters (8 feet).  Macroalgae was present in 8 of the 21 surveys (38%) but was not abundant in most. 

Volunteer measuring one of the four collected bay scallops in 2023 from Pensacola Bay. Photo: Gina Hertz.

Summary of Project

YearVolunteerGrids SurveyedTransects SurveyedLive Scallops Found
201587281010
201696311111
201754160
2018207320
2019136200
202052161
2021176240
20227422872
20237216774
TOTAL3174078
MEAN3514450.4

To date we are averaging 35 volunteers each event, surveying 14 of the 55 possible grids (25%).  We are averaging 45 transects each year (4500 m2), have logged 407 transects (40,700 m2) and have recorded 8 live scallops (< than one a year). 

Discussion

Based on the results since 2016 this year was a record year for live scallops.  Whether they are coming back on their own is still to be seen.  Being mass spawners, bay scallop need high densities in order to reproduce successfully, and these numbers do not support that.  The data, and comments from volunteers, suggest that the grasses look good and dense.  Thalassia, a favorite of the bay scallop, appear to be becoming more abundant.  This is a good sign. 

Though small and few, bay scallops are trying to hold on in Pensacola Bay. Photo: Gina Hertz