Farmed Oysters Never Go Out Of Style

Farmed Oysters Never Go Out Of Style

Growing up in the South, I was exposed to many “Old Wives’ Tales,” ranging from not cleaning your house or clothes on New Year’s Day to the one that everyone, including the northern states, knows, “don’t consume oysters in months without an R.”  While most “tales” are full of superstition, the “R” tale was one of biosecurity, and was mainly truthful until two new types of “R” came about; Regulations and Refrigeration. The tale came about due to the rise in food poisonings from shellfish in the warmer summer months that do not contain a “R,” such as June and July. The rise in food poisoning came about from the practices used by the oyster “tongers” at the time. Commercial harvest of wild oysters is a very labor-intensive job that requires long days on the water and constant tonging, measuring, and sorting of oysters as they come off the bottom. During the summer, the oysters would sit on the deck of the boat for hours in the heat, causing microorganisms and bacteria to flourish inside the closed oyster.  Bacteria, like Vibrio, would replicate to harmful levels inside of the oysters and when consumed by a human, could cause life-threatening illnesses.

That was then, and this is now. While the consumption of wild Florida oysters during the summer is not allowed (closed harvest season for wild oysters during the summer in Florida), you can still find oysters from all over the US, and farmed oysters from Florida are still allowed to be consumed during the summer. Biosecurity is a major factor involving food production and aquaculture, and without biosecurity, the consumption of Florida-farmed oysters would be prohibited. Oyster farmers in Florida must follow a very rigorous biosecurity plan that includes State-issued harvest times, water-to-refrigeration requirements, reporting of harvest and planting, and twice-daily temperature monitoring requirements. The regulations for harvest times and refrigeration requirements have scientific backing, showing a statistical difference in Vibrio concentrations between properly handled oysters and neglected oysters, with properly handled oysters having little to no concentrations of Vibrio. For instance, during the summer months, oyster farmers must have oysters harvested and in the cooler before 11am and down to 45°F within 2 hours of storing in cooler.  

Boat Full of Harvest Oysters
A farmer returns early morning from the lease with harvest oysters covered by burlap. This keeps the oysters “cool.” (Photo by: Thomas Derbes)

While there is an increased concentration of harmful bacteria during these warmer months, properly cared-for oysters help limit the growth and proliferation of the bacteria. Another myth is that Vibrio doesn’t exist in cold, winter waters. Vibrio can exist year-round, and people with health risks, including immune-suppressed patients and those with diabetes, should exercise extreme caution when consuming raw seafood. When purchasing seafood for personal consumption, make sure to bring a cooler with ice and place your seafood above the ice, making sure to not allow any fresh water to touch the seafood. When storing seafood at home, make sure they are in a container that can breathe, and cover with a moist paper towel to keep their gills wet. Oysters are typically good for 10-14 days after the harvest date, so make sure you check the tags and consume within time.

Next summer, when you see farmed oysters on the menu, remember the new R’s and order a couple dozen for the table. The need for support from your local oyster farmer is most needed during those months without R, so slurp them down all summer and thank your local oystermen and women!

Oyster with French Mignonette Sauce
Locally Farmed Oyster with French Mignonette (Photo by: Kelly Derbes)

Easy French Mignonette Recipe

Recipe for 2doz Oysters

¼ cup Red Wine Vinegar

¼ cup Champagne Vinegar

1 tablespoon of Finely Chopped Shallot

1 teaspoon of Fresh Crushed Black Pepper

Juice of ½ Lemon

Combine all ingredients together. Spoon over shucked, chilled raw oysters.

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
Meet the New Invasive Species on the Barrier Islands; Cogongrass

Meet the New Invasive Species on the Barrier Islands; Cogongrass

Miami is ground zero for invasive species in this state.  But the Florida panhandle is no stranger to them.  Where they are dealing with Burmese pythons, melaleuca, and who knows how many different species of lizards – we deal with Chinese tallow, Japanese climbing fern, and lionfish.  The state spends hundreds of thousands of dollars each year battling and managing these non-native problem species.  By definition, invasive species cause environmental and/or economic problems, and those problems will only get worse if we do not spend the money to manage them.  Those who work in invasive science and resource management know that the most effective way to manage these species is to detect them early and respond rapidly. 

The Invasive Species Curve

Invasive species have made their way to the coastal waters and dunes of the barrier islands in the Florida panhandle.  Beach vitex, Brown anoles, and Chinese tallow are found on most.  Recently on Perdido Key near Pensacola, we found a new one – cogongrass. 

Cogongrass (Imperata cylindrica) was accidentally introduced to the Gulf coast via crates of satsumas entering the port of Mobile in 1912.  It began to spread from there and has covered much of the upland areas of the southeastern U.S.  It has created large problems within pasture lands, where livestock will not graze on it, and in pine forest where it has decreased plant and animal biodiversity as well as made prescribed burning a problem – it burns hot, hot enough to actually kill the trees.  The impacts and management of this plant in that part of the panhandle has been known for a long time.  The Department of Agriculture lists it as one of the most invasive and noxious weeds in the country. 

Cogongrass seedheads are easily spotted in spring. Photo credit: Mark Mauldin

Two years ago cogongrass was discovered growing around a swimming pool area at a condo on Perdido Key.  To be considered an invasive species you must (a) be non-native to the area – cogongrass is certainly non-native to our barrier islands, (b) have been introduced by humans (accidentally or intentionally) – strike two, we THINK it was introduced by mowers.  This is a common method of spreading cogongrass, mowing an area where it exists, then moving those mowers to new locations without cleaning the equipment.  We do not know this is how it got to the island, but the probability is high.  Third, it has to be causing an environmental and/or economic problem.  It certainly is north of the I-10, but it is not known what issue it may cause on our barrier islands.  Could it negatively impact protected beach mice and nesting sea turtle habitat?  Could alter the integrity of dunes to reduce their ability to hold sand and protect properties.  Could it overtake dune plants lowering both plant and animal diversity thus altering the ecology of the barrier island itself?  We do not know.  What we do know is that if we want to eradicate it, we need to detect it early and respond rapidly. 

According to EDDMapS.org – there are 75 records of cogongrass on the barrier islands, and coastal beaches of the Florida panhandle.  This is most likely under reported.  So, step one would be to conduct surveys along your islands and beaches.  Florida Sea Grant and Escambia County of Marine Resources are doing just that.  EDDMaps reports five records on Perdido Key and four at Ft. Pickens.  It most likely there is more.  A survey of the northeast area of Pensacola Beach (from Casino Beach east and north of Via De Luna Drive) has found two verified records and two unverified (they are on private property, and we cannot approach to verify).  Surveys of both islands continue. 

The best time to remove/treat cogongrass is in the fall.  The key to controlling this plant is destroying the extensive rhizome system.  In the upland regions, simple disking has been shown to be effective if you dig during the dry season, when the rhizomes can dry out, and if you disk deep enough to get all of the rhizomes.  Though the rhizomes can be found as deep as four feet, most are within six inches and at least a six-inch disking is recommended.  Depending on the property, this may not be an option on our barrier islands.  But if you have a small patch in your yard, you might be able to dig much of it up. 

Chemical treatments have had some success.  Prometon (Pramitol), tebuthurion (Spike), and imazapyr have all had some success along roadsides and in ditches north of I-10.  However, the strength of these chemicals will impede new growth, or plantings of new plants, for up to six months.  There are plants that are protected on our islands and on Perdido Key any altering of beach mouse habitat is illegal.  We certainly do not want to kill plants that are holding our dunes.  If you feel chemical treatment may be needed for your property, contact the county extension office for advice. 

Most recommend a mixture of burning, disking, and chemical treatment.  But again, this is not realistic for barrier islands.  Any mechanical removal should be conducted in the summer to remove thatch and all older and dead cogongrass.  As new shoots emerge in late summer and early fall herbicides can then be used to kill the young plants.  Studies and practice have found complete eradication is difficult.  It is also recommended not to attempt any management while in seed (in spring).  Tractors, mowers, etc. can collect the seeds and, when the mowers are moved to new locations, spread the problem.  If all mowing/disking equipment can be cleaned after treatment – this is highly recommended. 

Step one would be to determine if you have cogongrass on your property, then seek advice on how to best manage it.  For more information on this species, contact your local extension office. 

New Gulf of Mexico Sea Grant Science Outreach Publications

New Gulf of Mexico Sea Grant Science Outreach Publications

The Gulf of Mexico Sea Grant Science Outreach Team is proud to announce four new outreach items that are applicable throughout the US and showcases marine microplastics and homeowners’ insurance:

How Hot Can You Go?  Warmer bay waters and the thermal maximums of estuarine creatures

How Hot Can You Go?  Warmer bay waters and the thermal maximums of estuarine creatures

I attended a meeting recently where one of the participants stated – “We have been looking at a lot of water quality parameters within our bay in recent years, and plan to look at more, but has anyone been looking at temperature?”

What he was referring to was that the focus of most monitoring projects has been nutrients, dissolved oxygen, etc.  But most agencies and universities who have been conducting long term monitoring in our bays are collecting temperature data as well.  His question was not whether they have or not but has anyone looked at this long-term temperature data to see trends. 

I know from some of the citizen science monitoring I have been involved with that temperature is collected but (anecdotally) does not vary much.  It is like pH, we collect it, it is there, but does change drastically (anecdotally) over time.  However, it has been a very hot year.  This “heat dome” that has been sitting over the Midwest and southeast this summer has set records all across the region.  Someone monitoring water temperature in East Bay recently reported surface water temperature at 96°F (36°C).  Many have stated that swimming in our waters at the moment feels like swimming in bath water.   It’s not just warm in your yard, it is warm in the bay.  And this brings up the question of thermal tolerance of estuarine species.

All creatures have a temperature tolerance range.  They resemble a bell curve where you have the thermal minimum at one end, the thermal maximum at the other, and the “preferred” temperatures near the top of the bell curve (see image below).  Many creatures have a large tolerance for temperature shifts (their bell curves extend over a larger temperature range).  You find such creatures in the temperate latitudes where temperature differences between summer and winter are larger.  Others have a lower tolerance, such as those who are restricted to polar or tropical latitudes.  Within an estuary you can find creatures with varying thermal tolerances.  Some have a larger tolerance than others.  Ectothermic (cold-blooded) creatures often have a wider range of temperatures they can survive at than endothermic (warm-blooded) ones.  Homotherms (creatures who maintain their body temperature near a fixed point – such as humans 98.6°F/37°C) expend a lot of energy to do this.  When environmental temperatures rise and fall, they have to expend more to maintain it at their fixed temperatures. 

Image provide by Research Gate.

It is also true that most creatures prefer to exist near their thermal maximum.  In other words, the bell curve is sort of skewed towards the warmer end of their range.  But what is their thermal maximum?  What happens when they reach it?  How hot can they go?

Local waters are warmer this year. Photo: Rick O’Connor

The studies I reviewed suggested that the thermal maximum is dependent on other environmental factors such as salinity and dissolved oxygen.  In most cases, the higher the salinity, the higher the thermal maximum was.  I looked at studies for the eastern oyster (Crassostrea virgincia), the brown shrimp (Farfantepenaeus aztectus), the blue crab (Callinectes sapidus), the Spot Croaker (Leiostomus xanthurus), and the pinfish (Lagodon rhomboides).  The oyster, shrimp, and blue crab support important commercial fishery.  The spot croaker is a dominant fish species in the upper estuary where the pinfish is a dominant species in the lower sections.  These studies all suggested that again, depending on salinity, dissolved oxygen, pressure, and rate of temperature increase, the thermal maximum could happen as low as 30°C (86°F) and as high as 40°C (104°F), with many having a thermal maximum between 35-40°C. 

At these temperatures proteins begin to denature and biological systems begin to shut down.  Most of the studies determined the endpoint at “loss of equilibrium” and not actually death.    Our estuaries can certainly reach these temperatures in the summer.  Again, one recent reading in East Bay (within the Pensacola Bay system) was 96°F (36°C). 

So, what do these creatures do when such temperatures are reached?

The most obvious response is to move, find cooler water.  These are often found in deeper portions of the bay below the thermocline (a point in the water column where water temperatures significantly change – usually decreasing with depth).  However, many sections of our estuaries are shallow and deep water cannot be found.  In these cases, they may move great distances to seek deeper water areas, or even move to the Gulf of Mexico.  In some cases – like with oysters – they cannot move, and large die-offs can occur.  Other responses include lower metabolic rates and decline in reproduction. 

We know that throughout history, there have been warmer summers than others and heat waves have happened.  In each case, depending on other environmental factors, estuarine creatures have adapted, and some members have survived, to keep their populations going. 

We know that large scale die-offs have occurred in the past and the tougher species have continued on. 

We also know that the planet is warming, and it would be interesting to look at how the water temperatures have changed over the last few decades.  Are they increasing?  Are they reaching the thermal maximums of the creatures within our bay?  How will these creatures respond to this? 

How hot can they go?

Meet the Barnacle

Meet the Barnacle

You might say this is a strange title – “meet the barnacle” – because everyone knows what a barnacle is… or do they? 

As a marine science instructor, I gave my students what is called a lab practical.  This is a test where you move around the room and answer questions about different creatures preserved in jars.  Almost every time that got to the barnacle they were stumped.  I mean they knew it was a barnacle but what kind of animal is it?  What phylum is it in? 

Going through a thought process they would more often than not choose that it was a mollusk.  This makes perfect sense because of the calcium carbonate shell it produces.  As a matter of fact, science thought it was a mollusk until 1830 when the larval stage was discovered, and they knew they were dealing with something different.  It is not a mollusk.  So… what IS it?  Let’s meet the barnacle…

Barnacles along the seashore is a common site for many. Photo: NOAA

The barnacle is actually an arthropod.  Yep… the same group as crabs and shrimp, insects and spiders.  Weird right…

But that is because the creature down within that calcium carbonate shell is more like a tiny shrimp than an oyster.   It is in the class Cirripedia within the subphylum Crustacea.  It is the only animal in this class and the only sessile (non-motile) crustacean. 

Barnacles are exclusively marine.  This has been helpful when conducting surveys for terrapins or assessing locations for living shorelines – if you see barnacles growing on rocks, shells, or pilings, it is salty enough.  There are over 900 species described and they live independently from each other attached to seawalls, rocks, pilings, boats, even turtle shells.  Louis Agassiz described the barnacle as “nothing more than a little shrimplike creature, standing on its head in a limestone house kicking food into its mouth.” 

This image from a textbook shows the internal structure of a barnacle. Notice the shrimplike animal on its back with extendable appendages (cirri) for feeding. Image: Robert Barnes Invertebrate Zoology.

The planktonic barnacle larva settles to the bottom and attaches to a hard substrate using a cement produced from a gland near the base of their first set of antenna (crustaceans, unlike insects and spiders, have two sets of antenna).  It is usually head down/tail up and begins to secrete limestone plates forming the well known “shell” of the animal.  Some barnacles produce a long stalk near the head end (called the peduncle) which holds the adhesive gland and it is the peduncle that attaches to the hard substrate, not the head directly.  The goose neck barnacle is an example of this.  We find them most often in the wrack along the Gulf side of our beaches attached to driftwood or marine debris. 

Lucky was found in the Gulf of Mexico. He had been there long enough for these goose neck barnacles to attach and grow. Photo: Bob Blais

The “shell” of the barnacle is a series of calcium carbonate plates they secrete.  These plates overlap and are connected by either a membrane or interlocking “teeth”.  The body lies 90° from the point of attachment on its back. 

There are six pairs of “legs” which are very long and are extended out of the “doors” of the shell and make a sweeping motion to collect planktonic food in the water column.  They are most abundant in the intertidal areas were there are rocks, seawalls, or pilings. 

Most species are hermaphroditic (possessing both sperm and egg) but cross fertilization is generally the rule.  Barnacles signal whether they are acting males or females via pheromones and fertilization occurs internally, the gametes are not discharged into the water column as in some mollusks and corals.  The developing eggs brood internally as well.  Our local barnacle (Balanus) breeds in the fall and the larva (nauplius) are released into the water column in the spring by the tens of thousands.  The larva goes through a series of metamorphic changes until it settles on a hard substrate and becomes the adult we know.  They usually settle in dense groups in order to enhance internal fertilization for the next generation.  Those who survive the early stages of life will live between two and six years. 

So, there you go… this is what a barnacle is… a shrimplike crustacean who is attached to the bottom by its head, secretes a fortress of calcium carbonate plates around itself, and feeds on plankton with its long extending legs.  A pretty cool creature. 

Reference

Barnes, R.D. 1980. Invertebrate Zoology. Saunders College Publishing.  Philadelphia PA.  pp. 1089.