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 In fact, there is a small, but vocal, anti-aquaculture activist groups that often uses false or outdated information to undermine public confidence and resists even low-impact or environmentally responsible operations.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 NetpenFreeport High School Students exploring Ocean Reports tool.
A Lionfish Removal and Awareness Day festival volunteer sorts lionfish for weighing. (L. Tiu)
The northwest Florida area has been identified as having the highest concentration of invasive lionfish in the world. Lionfish pose a significant threat to our native wildlife and habitat with spearfishing the primary means of control. Lionfish tournaments are one way to increase harvest of these invaders and help keep populations down. Not only that, but lionfish are a delicious tasting fish and tournaments help supply the local seafood markets with this unique offering.
Since 2019, Destin, Florida has been the site of the Emerald Coast Open (ECO), the largest lionfish tournament in the world, hosted by Destin-Fort Walton Beach and the Florida Fish and Wildlife Commission (FWC). While the tournament was canceled in 2020, due to the pandemic, the 2021 tournament and the Lionfish Removal and Awareness Day festival returned to the Destin Harbor May 14-16 with over 145 tournament participants from around Florida, the US, and even Canada. The windy weekend facilitated some sporty conditions keeping boats and teams from maximizing their time on the water, but ultimately 2,505 lionfish were removed during the pre-tournament and 7,745 lionfish were removed during the two-day event for a total of 10,250 invasive lionfish removed. Florida Sea Grant and FWC recruited over 50 volunteers from organizations such as Reef Environmental Education Foundation, Navarre Beach Marine Science Station and Tampa Bay Watch Discovery Center to man the tournament and surrounding festival.
Lionfish hunters competed for over $48,000 in cash prizes and $25,000 in gear prizes. Florida Man, a Destin-based dive charter on the DreadKnot, won $10,000 for harvesting the most lionfish, 1,371, in 2 days. Team Bottom Time secured the largest lionfish prize of $5,000 with a 17.32 inch fish. Team Into the Clouds wrapped up the $5,000 prize for smallest lionfish with a 1.61 inch fish, the smallest lionfish caught in Emerald Coast Open History.
It is never too early to start preparing for the 2022 tournament. For more information, visit EmeraldCoastOpen.com or Facebook.com/EmeraldCoastOpen. For information about Lionfish Removal and Awareness Day, visit FWCReefRangers.com
A great blue heron enjoying the Gulf of Mexico. Photo: Chris Verlinde
June is National Ocean Month. Close your eyes and think about just how many oceans there are. Surprise, there is only one! The ocean is huge, covering over 70 percent of the earth’s surface. Traditionally, the ocean was divided into four named ocean basins: the Pacific, Atlantic, Indian, and Arctic. However, most countries, including the United States, now recognize the Southern (Antarctic) as the fifth ocean. No matter where you live, you are connected to our one global ocean.
What do you know about our ocean? The ocean is where life began over 3.5 billion years ago. The ocean covers over 70% of the Earth’s surface and includes over 96% of the Earth’s water. Australia’s Great Barrier Reef is the largest living structure on Earth and can be seen from the moon! The deepest part of the ocean is in the Mariana Trench, and nearly 7 miles beneath the waves! Coral reefs cover only 1/50th of the ocean floor but about one quarter of all the marine species make coral reefs their home. No light penetrates the ocean at depths greater than 3,280 feet. Aided by deep diving rovers and remote sensing cameras, scientists are still discovering new species beneath the waves. The Gulf Stream transports more water than all the Earth’s rivers combined. The mid-ocean ridge crisscrosses the globe for over 40,000 miles and is the largest geological feature on Earth. Did you know that about 95% of the ocean remains unexplored?
What about our beloved Gulf of Mexico? Is it an ocean? No! While both oceans and gulfs are large bodies of saltwater, gulfs are smaller and are bordered on three sides by land. In the case of the Gulf of Mexico, it’s bordered by the United States and Mexico. So, although it is large and salty like the ocean, the Gulf of Mexico is considered part of the Atlantic Ocean.
This is not a word that most visitors to the beach want to hear. However, shark attacks are actually not that common and the risk is very low. People hear this every year on shark programs, but it does not seem to make them feel any better. Here is what the International Shark Attack File says (as of 2020)…
–Since the year 1580 there have been 3164 unprovoked shark attacks around the world.
Let that sink in for a moment… 3000 unprovoked attacks on humans in the last 440 years.
Now consider the number of car accident victims that have occurred in the last month within the United States. See what they are getting at? Let’s look at more…
–Of the 3164 reported unprovoked attacks (yes… these data only include what was reported) 1483 were from the United States… 47% of them. This may be due to the fact we are “water people”. The other top countries are Australia, South Africa, and Brazil, all “water people” as well.
–Of the 3164 reports 851 were from Florida (27%). This is the number of reported shark attacks in our state since the Spanish settled it. This comes out to 2 each year – though the data shows a sharp increase in attacks starting in the 1970s (most have occurred since then).
–Of the 3164 reports 25 were from the panhandle region (0.8%) and 7 from the Pensacola Bay area (0.2%).
Let that sink in for a moment. Seven reported attacks from the Pensacola Beach area since the time DeLuna landed here in 1559… 7.
And lets once again consider the number of vehicle accidents that will occur in the bay area today.
These numbers have been posted before. Yet people are still very worried when the hear sharks are in the Pensacola Beach region. When attacks occur, they are big news. The International Shark Attack File does give trends and suggestions on what to do. But as many say, sharks are the least of your worries when you are planning a day at the beach.
Now that we have said all of that, they are truly amazing animals.
They are fish but differ in that their skeletons lack hard calcified bone – they are cartilaginous. There are 25 species in 9 different families in the Gulf of Mexico. Many are completely harmless – 13 of the 25 have been reported to have had unprovoked attacks somewhere around the world – the white, tiger, and bull sharks leading the way. Several rarely come close to shore.
Sharks lack a swim bladder and thus cannot “float” in the water column the way your aquarium fish do. Some, like the nurse and angel sharks, rest on the bottom. Others, like the white and blue sharks, swim constantly to get water flowing over their gills.
Because of this, they are very streamlined with reduce scales. They actually have modified teeth for scales – called placoid scales. Their fins are angular and rigid (as are other open water fish) and some can swim quite fast – makos have been clocked at over 30 mph for short distances. Many have seen video of large white sharks exploding with a burst of speed on a sea lion and actually leaping out of the water with it.
Many species do lay eggs, but others keep the eggs within and give live birth after they hatch. One species, the sand tiger, produce four embryos within the mother. The first to hatch consumes the other three!
The teeth of sharks are famous. Rows of them, some pointed, some are serrated, all are designed to cut and swallow. The tiger shark has a serrated tooth that is angled like a can opener. They can use this to “open” sea turtle shells – adding them to their rather large menu. They “shed” these frequently – placing a new sharp tooth where the dull old one was – and will go through tens of thousands of teeth in a lifetime.
The sensory system is one of the most amazing in the world. Tiny gelatinous cells along their sides, called the lateral line, detect pressure waves from great distances. Splashing, thrashing movements made by fish can be detected a mile away – and get their attention. As they approach the sound their sense of smell kicks in. It has been said that a shark can detect one drop of blood in thousands of gallons of water – and it is true. However, the sharks must be down current of the victim to detect it. Their eyes are much better than most think. They have “crystals” within their retina that act as mirrors reflecting light that enters. Imagine turning on a flashlight in a dark room. Now imagine doing this if the walls and ceiling were mirrors – you kind of understand how they can actually see pretty well even in the low light. That said, light does not travel well under water, so they rely on their other senses more. And as if that were not enough. They have small gelatinous cells around the head region that can detect small electric fields. When a shark bites, it must close its eyes and – as the fishermen say – “roll back” out of the head. At this point the shark is basically blind and cannot see the target it is trying to bite. However, if you move out of the way, the weak electric fields produced by your muscles in doing so can be detected by these cells and the shark knows where you are.
Cool – and scary at the same time. Let’s meet a few of these amazing fish in our area.
The nurse shark. Notice the barbels (whiskers) on its head. Photo: NOAA
NurseShark
This is one of the bottom dwelling sharks that appear harmless – and they are – but if provoked, they will bite. They have less angular fins, or a brownish-bronze color, and really like structure – they are found on our reefs. They posses a “whisker-like” structure called a barbel. These are common on other bottom fish, like catfish, and possess chemo-sensory cells to detect prey buried in the sand. They are not as common here as they are in the Keys, but they have been seen. They can reach lengths of 14 feet.
Blacktip sharks are one of the smaller sharks in our area reaching a length of 59 inches. They are known to leap from the water. Photo: Florida Sea Grant
Blacktip – Spinner
These are grouped together because (a) they resemble each other, and (b) they are both common here.
They are both stream-lined in shape and have blacktips on their fins. Actually, spinner sharks have more fins tipped-black than the blacktip. The anal fin of the spinner is tipped black, but this is not the case for the blacktip. The spinner gets its name from the habit of leaping from the water and spinning very fast as it does so. Both are quite common in the Gulf and the bay. They reach about eight feet in length and unprovoked attacks are very rare.
The Scalloped Hammerhead is one of five species of hammerheads in the Gulf. It is commonly found in the bays. Photo: Florida Sea Grant
Hammerheads
This is a creepy group – check out the head. It is one that many people fear, and unprovoked attacks have occurred. The reader may not know that there are more than one kind – five species actually. They have a tall dorsal fin which sometimes extends above the water when swimming near the surface – the classic “shark is coming” look. Their heads are aerofoil shaped and there are several possible explanations for this. 1) It is more aerodynamic, making it easier for this ram-jetter to swim, using less energy to do so. 2) It is a battery of sensory cells. By swinging the head back and forth, as they do, it is an advanced radar searching for prey, possibly finding it before other sharks do. There are stories of hammerheads arriving first. 3) It is also believed they use their electric sense to detect buried prey – the shape making this easier to find and expose them. It could very well be that all of these could explain the shape.
This pregnant bull shark has an impressive girth.
Bull Shark
Since the film Jaws the world has turned its attention from solely the white shark – to the bull shark. As you can imagine, it is hard for a shark attack victim to tell you which species bit them – “I don’t know… it was a big gray thing chomping on my leg!” or “It was a great white!” because that is the only one many know. But studies sine the 1970s suggest that the bull shark is an aggressive species and may be responsible for a lot of attacks. Particularly in the estuaries and upper estuaries. Bull sharks are what we call euryhaline – they have tolerance for a wide range of salinities. This shark has been reported in low salinities of the upper estuaries and even into freshwater rivers. One report had them over 100 miles from the coast – they are certainly where the people are.
The extremely long upper lobe of the thresher shark. Image: NOAA
ThresherSharks
These are bizarre looking sharks. Most sharks have what we call a heterocercal tail – different – different meaning the upper lobe of the forked tail is longer than the lower. But the threshers take this to the extreme – the tail can make up almost half of their body length, which can be 20 feet. It is believed that use this extremely long tail to herd and stun baitfish – their favorite prey. They prefer colder waters and records in the Gulf are not common. Those that exist suggest they live offshore and are rarely encountered near beaches. There are no unprovoked attacks reported from this shark.
The massive whale shark. Photo: Florida Museum of Natural History.
WhaleShark
Amazing… heart stopping… what else can you say. Encounters with the largest fish on our planet are rare – but when they do happen you will never forget it – it will be one of the highlights of your life. As the name suggest – these are large sharks, with a mean length of 45 feet but some reporting in at 60 feet. They are easily recognized first by their size, but also their coloration. They are brownish color with beige or white spots in nice rows running across the dorsal side. They swim slowly filtering plankton from the sea – though will occasionally take in a fish. Some reports show them vertical in the water column moving up and down filtering from a school of plankton or tiny fish. They are rarely seen because they tend to dive deeper during the day with the plankton layer – then surfacing at night following the same plankton. They are, unfortunately, sometimes struck by boats while at the surface.
This is a good name for this group. They are mollusk that have two shells. They tried “univalve” with the snails and slugs, but that never caught on – gastropods it is for them. The bivalves are an interesting, and successful, group. They have taken the shell for protection idea to the limit – they are COMPLETELY covered with shell. No predators… no way. But they do have predators – we will talk more on that.
An assortment of bivalves, mostly bay scallop. Photo: Florida Department of Environmental Protection.
As you might expect, with the increase in shell there is a decrease in locomotion – as a matter of fact, many species do not move at all (they are sessile). But in a sense, they do not care. They are completely covered and protected. Again, we will talk more about how well that works.
The two shells (valves) are connected on the dorsal side of the animal and hinged together by a ligament. Their bodies are laterally compressed to fit into a shell that is aerodynamic for burrowing through soft muds and sands. Their “heads” are greatly reduced (even missing in some) but they do have a sensory system. Along the edge of the mantle chemoreceptive cells (smell and taste) can be found and many have small ocelli, which can detect light. The scallops take it a step further by having actually eyes – but they do live on the surface and they do move around – so they are needed.
The shells are hinged together at the umbo with “teeth like structures and the shells open and close using a pair of adductor muscles. Many shells found on the beach will have “scars” which are the point of contact for these muscles. They range is size from the small seed clams (2mm – 0.08”) to the giant clam of the Indo-Pacific (1m – 3.4 ft) and 2500 lbs.! Most Gulf bivalves are more modest in size.
Being slow burrowing benthic animals, sand and mud can become a problem when feeding and breathing. In response, many bivalves have developed modified gills to help remove this debris, and many actually remove organic particles using it as a source of food. Many others will fuse their mantle to the shell not allowing sediment to enter. But some still does and, if not removed, will be covered by a layer of nacreous material forming pearls. All bivalves can produce pearls. Only those with large amounts of nacreous material produce commercially valuable ones.
Coquina are a common burrowing clam found along our beaches. Photo: Flickr
Another feature is the large foot, used for digging a burrowing in the more primitive forms. It is the foot we eat when we eat clams. They can turn their bodies towards the substrate, begin digging with their foot but also using their excurrent from breathing to form a sort of jet to help move and loosen the sand as they go – very similar to the way we set pilings for piers and bridges today.
These are the earliest forms of bivalves – the burrowers. Most are known as clams and most live where the sediment is soft. Located near their foot is a sense organ called a statocyst that lets them know their orientation in the environment. Most have their mantles fused to their shells so sand cannot enter the empty spaces in the body. To channel water to the gills, they have developed tubes called siphons which act as snorkels. Most burrow only a few inches, some burrow very deep and they are even more streamlined and elongated.
Some have evolved to burrow into harder material such as coral or wood. One of the more common ones is an animal called a shipworm. Called this by mariners because of the tunnels they dig throughout the hulls of wooden ships, they are not worms but a type of clam that have learned to burrow through the wood consuming the sawdust of their actions. They have very reduced shells and a very long foot.
This cluster of green mussels occupies space that could be occupied by bivavles like osyters.
Other bivalves secrete a fibrous thread from their foot that is used to grab, hold, and sometimes pull the animal along. These are called byssal threads. Many will secrete hundreds of these, allow them to “tan” or dry, reduce their foot, and now are attached by these threads. The most famous of this group are the mussels. Mussels are a popular seafood product and are grown commercial having them attach to ropes hanging in the water.
Another method of attachment is to literally cement your self to the bottom. Those bivalves who do this will usually lay on their side when they first settle out from their larval stage and attach using a fluid produced by the animal. This fluid eventually cements them to the bottom and the shell attached is usually longer than the other side, which is facing the environment. The most famous of these are the oysters. Oysters basically have lost both their “head” and the foot found in other bivalves. These sessile bivalves are very dependent on tides and currents to help clear waste and mud from their bodies.
Oysters are a VERY popular seafood product along the Gulf coast. Photo: Rick O’Connor
Then there are the bivalves who actually live on the bottom – not attached – and are able to move, or even swim. Most of these have well developed tentacles and ocelli to detect danger in the environment and some, like the scallops, can actually “clap their shells together” to create a jet current and swim. This is usually done when they detect danger, such as a starfish, and they have been known to swim up to three feet. Some will use this jet as a means of digging a depression in the sand they can settle in. In this group, the adductor has been reduced from two (the number usually found in bivalves) to one, and the foot is completely gone.
As you might guess, reproduction is external in this group. Most have male and female members but some species (such as scallops and shipworms) are hermaphroditic. The gametes are released externally at the same time in an event called a mass spawning. To trigger when this should happen, the bivalves pay attention to water temperature, tides, and pheromones released by the opposite sex or by the release of the gametes themselves.
Scallop life cycle. Image: University of Florida IFAS
The fertilized eggs quickly develop into a planktonic larva known as a veliger. This veliger is ciliated and can swim with the current to find a suitable settling spot. Some species have long lived veliger stages. Oysters are such and the dispersal of their veliger can travel as far as 800 miles! Once the larval stage ends, they settle as “spat” (baby shelled bivalves) on the substrate and begin their lives. Some species (such as scallop) only live for a year or two. Others can live up to 10 years.
As a group, bivalves are filter feeders, filtering organic particles and phytoplankton as small as 1 micron (1/1,000,000-m… VERY small). In doing this they do an excellent job of increasing water clarity which benefits many other creatures in the community. As a matter of fact, many could not survive without this “eco-service” and the loss of bivalves has triggered the loss of both habitat and species in the Gulf region. Restoration efforts (particularly with oysters) is as much for the enhancement of the environment and diversity as it is for the commercial value of the oyster.
Now… predators… yes, they have many. Though they have completely covered their bodies with shell, there are many animals that have learned to “get in there”. Starfish and octopus are famous for their abilities to open tightly closed shells. Rays, some fish, and some turtles and birds have modified teeth (or bills) to crush the shell or cut the adductor muscle. Sea otters have learned the trick to crush them with rocks and some local shorebirds will drop them on roads and cars trying to access them. And then there are humans. We steam them to open the shell and cut their adductor muscle to reach the sweet meat inside.
It is a fascinating group – and a commercial valuable one as well. Lots of bivalves are consumed in some form or fashion worldwide. Take some time at the beach to collect their shells as enjoy the great diversity and design within this group. EMBRACE THE GULF!
