A Brief Explanation About Triploid Oysters

A Brief Explanation About Triploid Oysters

When you sit down and enjoy some fresh, farmed oysters during the summer, you might notice that the oyster is not watery but yet plump and full of meat, unlike the usual wild oysters. These farmed oysters are very special and are called “triploid oysters.” What makes an oyster a triploid? Well, it all starts in the oyster hatchery and involves using tetraploid male oysters to breed with diploid female “wild” oysters.

Before we dive into triploids, let’s go over some definitions. A diploid organism contains two sets of chromosomes. As humans, we have two sets of chromosomes, and the pair is formed by a chromosome from the mother and a chromosome from the father. Triploid organisms contain three sets of chromosomes and while very rare, triploidy does happen in the wild. Tetraploid organisms have four sets of chromosomes and are usually only formed in a laboratory setting using pressure or other means to cause tetraploidy. When you breed a tetraploid oyster with a diploid oyster, the result is a triploid oyster.

Spawning Chamber
A hatchery worker keeping an eye on spawning chambers with diploid oysters – Thomas Derbes II

Inside of an oyster hatchery, you will see many small breeding chambers for the oysters. When a hatchery decides to spawn oysters, they place a single wild diploid oyster in each chamber. During spawning, the hatchery will introduce a cycle of cold then warm water and this cycle is repeated until a spawn is triggered. Hatchery workers will closely watch the oysters and will shut off the water supply to any oyster that has spawned so they can trap the gametes in the chamber. You can determine the sex of an oyster by watching it spawn; a female oyster “claps” out her eggs while a male opens slightly and releases sperm into the water. When spawning for triploid oysters, the hatchery workers will only obtain the eggs from female diploid oysters and discard any diploid sperm to avoid cross contamination. During the spawn, a worker will strip the sperm from male tetraploid oysters and once all female diploids are done spawning, they will introduce the tetraploid sperm to the diploid eggs. After 30 minutes, fertilization rates are calculated and stocking densities are formed.

Tub of Triploid Oyster Seed
3-month-old triploid seed – Thomas Derbes II

Why Would a Farmer Want to Grow a Triploid Oyster?

There are many benefits for a farmer to raise triploid oysters. First and foremost, triploid oysters are sterile. This is a major benefit for the farmers during the summer months. During the summer, wild diploid oysters spawn, and when they spawn, the meat turns very thin and watery. In the Panhandle of Florida, the harvest of wild oysters is prohibited in the summer and only farmed oysters can be harvested.

Another added benefit is the increased growth rate of a triploid oyster compared to a diploid oyster. As mentioned above, triploid oysters lack the ability to spawn. Since a triploid oyster does not have to spend energy producing gametes, it puts all of its energy into growing its shell and meat. A typical diploid oyster could take more than two years to reach harvest size, where a triploid oyster can reach harvest size within 8 months (commonly 12-24 months but there are usually some fast growers in a batch).

There are more benefits of triploid oysters including selective breeding for disease resistance and environmental sustainability. With the use of triploid oysters for oyster farming, wild stocks go relatively unaffected and help contribute to more sustainable aquaculture practices. I hope this brief explanation of triploid oysters will help you understand more about the somewhat unknown world of oyster aquaculture. With demand for oysters on the rise, triploid oysters hold great promise in meeting the needs of an ever-growing oyster aquaculture industry.

It’s Been a Cruel Summer, Especially for Southern Oyster Farmers

It’s Been a Cruel Summer, Especially for Southern Oyster Farmers

There is a term that all oyster farmers dislike, it is almost like that one villain from a famous book/movie series where they shouldn’t say his name. That term is “unexplained spring/summer mortality” and it has been a growing issue along with the expansion of oyster farming throughout the southeast. While the art of oyster farming has been around since the time of the Romans, it is a relatively new venture here in the Gulf of Mexico, and Florida is home to over one hundred oyster farms. These farms are meticulously cared for by the oyster farm crew, with many different anti-fouling techniques and biosecurity measures in practice to provide the customer with a safe, clean product that you can consume even in the months without an R (another article on that coming later). Each year, farm managers can expect a 10-30% mortality event during the transition from winter into spring/summer, hence the term “unexplained spring/summer mortality.” Researchers and scientists from all over the southeast have been actively working to find a cause for this phenomenon, but the answer has been hard to find.

Dead, market ready oysters from one bag. Cause of death, “Unexplained Mortality Event 2022”
Photo by: Thomas Derbes II

Our Pensacola Bay has been a hotbed for oysters lately; The Nature Conservancy recently constructed 33 oyster beds along Escribano Point in East Bay, the establishment of the Pensacola & Perdido Bay Estuary Program, acquisition of a $23 million restoration grant with $ 10 million towards 1,482 acres of oyster restoration, and the establishment of oyster farms and hatcheries. In Pensacola Bay, there are currently 5 oyster farms in operation, one of those farms being a family-owned and operated Grayson Bay Oyster Company. Brandon Smith has been managing the business and farm for over 4 years now and has experienced mortality events during those prime spring/summer months. In recent years, they have experienced mortality events ranging from minimal to what many would consider “catastrophic,” and reports from around Florida and the Southeast convey a similar message. Concerned for not only the future of his family farm, but other oyster farms in the Southeast, he has been working with the most experienced institutions and groups in 2022 to possibly get an answer on his and other local “unexplained mortality events.” Each road led to the same answer of “we aren’t quite sure,” but this didn’t deter Smith or other the farmers who are dealing with similar issues.

In 2023, Smith was invited to participate in a Florida-Wide program to track water quality on their farm. This project, led by Florida Sea Grant’s Leslie Sturmer from the Nature Coast Biological Station in Cedar Key, Florida, hopes to shed some light on the changes in water quality during the transition from winter to spring and spring to summer. Water samples have also been taken weekly to preserve plankton abundance and the presence of any harmful algae if a mortality event does occur. With the hottest July on record occurring in 2023, temperature could play a role in mortality events, and now researchers are equipped with the right tools and open lines of communication to possibly find a solution to the problem.

3-month-old seed being deployed out on Grayson Bay Oyster Company’s farm in Pensacola, Florida (2023).
Photo by: Thomas Derbes II

As with traditional farming on land, oyster farming takes a mentally strong individual with an incredible work ethic and the ability to adapt to change. The Southeast has a resilient system of oyster farmers who display these traits and continue to put their noses down and “plant” seed every year for the continuation of a growing yet small industry, even through the hardest of trials and tribulations. Through collaboration with local and state institutions, stakeholders, programs, and citizens, oyster farmers are hopeful that they can solve this “unexplained mortality event” and help develop resilient farming techniques. An important message is local farms that have environmental and economic impacts cannot exist without the support of their community.

If you’re interested in tracking water quality on select farms, including Grayson Bay Oyster Company, the website is https://shellfish.ifas.ufl.edu/farms-2023/ and it is updated monthly.        

Offshore Aquaculture: Siting Tools

Offshore Aquaculture: Siting Tools

Aquaculture is growing faster than any other animal food-production sector.  The development of new technologies, stagnation of wild capture fisheries, and the increase in seafood demand are all contributing to a 5.3% increase in aquaculture production within the last two decades (FAO, 2020). While global aquaculture production continues to expand, the U.S. is experiencing a seafood trade deficit of $14 billion.  The U.S. is clearly in urgent need of more domestic seafood production.

Aquaculture is a growing industry in Florida and one of the best opportunities for expanding seafood production is in offshore or open-ocean marine aquaculture. Offshore aquaculture production has the potential to help meet the protein requirements for a burgeoning population and provide seafood security.  Additionally, it can help support working waterfront communities and even enhance recreational dive tourism and recreational fishing.  However, the complexity of offshore production is not fully understood by the public.  In fact, there is a small, but vocal, anti-aquaculture activist groups that often uses false or outdated information to undermine public confidence and resists even low-impact or environmentally responsible operations.  Identified concerns include that the expansion of marine aquaculture will adversely impact fishing, harm coastal communities, and degrade the oceans for other recreational users.

Proper siting of offshore aquaculture farms can address many of the identified concerns.  In response, NOAA scientists have developed a tool, Ocean Reports, that can instantaneously analyze more than 100 ocean datasets to develop maps, graphics, and other details of selected areas in the Gulf of Mexico and beyond.  Users can get detailed information about habitats and species, industries in the area, potential hazards (such as undersea cables or shipwrecks), the economic value of ocean commerce, and other detailed oceanographic information.

Ocean reports has data useful to industry and science, but is user-friendly enough for other stakeholders, including students.  Recently, students studying aquaculture at Freeport High School in Freeport, FL used the tool to search for potential offshore aquaculture sites off the coast of Florida.  The tool is fun and easy to use, so feel free to visit the website to give it a try.  https://www.marinecadastre.gov/oceanreports

Offshore Aquaculture Netpen
Freeport High School Students exploring Ocean Reports tool.
Is Tuna Trendy?

Is Tuna Trendy?

February is American Heart Month and when I think of heart, my thoughts turn to seafood.  Perhaps that is unusual, but I love seafood and the fact that the American Heart Association recommends 1 to 2 seafood meals a week fits right into my gastronomic plans. More seafood on your table can improve your overall health and help fight off infections.

During the recent pandemic, an increase in home cooking has resulted in a rise in seafood consumption.  Consumers rediscovered frozen and canned fish, a trend that continues today.  Canned tuna and fish stick consumption rose as home cooks perfected their tuna melts and fish sandwiches. Home chefs throwing fish steaks, aluminum wrapped fillets, shrimp, and even oysters on the grill have raised the bar on home-cooked meals.

Other new trends on the horizon are more innovative. How do Atlantic salmon hot dogs sound?  High-end canned and jarred seafood, think canned smoked oysters, are gaining in popularity as well as being quick and easy to prepare. Nose to tail is another trend that promotes maximum utilization of the whole seafood product.  Cooking fish whole or tanning fish skins for an upscale leather are new ways to enjoy seafood. Want to try something new? Sea vegetables, including kelp and other seaweed are taking the culinary world by storm because of their great taste and nutritional benefits.

Let us not forget about our furry friends.  Sustainable seafood-based pet treats are gaining quite a bit of market share.  Seafood has one of the lowest environmental footprints of any protein, and as such makes a great, healthy, sustainable snack for fido.

Sustainable seafood, both wild and farm-raised, is an option that is good for your heart and good for the planet. Buying sustainably harvested or raised seafood is one way you can do your part to protect the ocean and ensure plentiful seafood for the future. Make a resolution to try a new product, recipe, or cooking method during this month to celebrate a healthy heart.

Cooked red snapper (Photo credit: L. Tiu)

The World is Your Oyster

The World is Your Oyster

There are a lot of good oyster quotes. One I remember from childhood is the saying to only eat oysters in months with the letter “r,” basically September to April. I believe this originated when all oysters came from the wild. This was a way to avoid the hot months that may have led to a watery oyster, or even food poisoning. Today, with the rise of oyster aquaculture and refrigeration, oysters can be enjoyed year-round.

The Florida Fish and Wildlife Conservation Commission recently made the tough decision to shut down wild oyster harvesting in Apalachicola, FL for up to five years in response to a struggling bay oyster population threatened by water flow issues and overharvesting. This was devastating news to an area that historically produced 90% of the state’s oysters and 10% of the nation’s. On the bright side, oyster aquaculture has been steadily growing in the area and is working hard to fill some of the gap.

A team of Florida Sea Grant Agents recently made a visit to Apalachicola to learn more about this historic oyster town and how the industry is adapting. Our first stop was Water Street Seafood, the Florida Panhandle’s largest seafood distributer. Water Street provides a wide diversity of both fresh and frozen seafood, including oysters, delivering daily in northwest Florida and shipping worldwide. We visited their oyster processing facility where we saw mesh bags of oysters brought in from Louisiana and Texas. The oysters, both farmed and wild caught, are carefully cleaned and sorted, with some going to the live, halfshell, restaurant market and some shucked onsite for the shucked market.

Next, we visited one of the many new oyster aquaculture farms in the area. Oysters farms are permitted by the state and are located in waters that have been carefully evaluated for their suitability for oyster production. Small plots are leased to the farmer allowing off-bottom production in mesh bags teathered with anchors in the shallow, productive bay waters. Oyster farmers tend to their crop by turning the bags regularly to reduce fouling of the oyster shell, and sorting by size as the oyster grows. Oysters take between eight to eighteen months to reach a harvest size.

Given the increasing demand for oysters by tourists and locals, we can thank aquaculture for keeping these tasty gems on our plates. If you are lucky enough to find some locally raised oysters on the menu, take the opportunity to try something new and support a local farmer.

An oyster farmer visiting his lease to monitor his crop. (credit: L. Tiu)
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Fresh live oysters from an Apalachicola Oyster Farm (credit: L. Tiu)

Oyster bag holding cooler at Water Street Seafood with green bags holding wild caught oysters and purple bags holding farm raised oysters. (credit: L. Tiu)