In recent weeks, the country has heard about shark attacks off the Carolina coast and great whites off the northern coast of the Gulf of Mexico – then of course, we just completed “Shark Week”. This sometimes makes visitors to our beaches a bit unnerved about swimming. Each year we hear about how other activities we engage in are much more dangerous than swimming in the Gulf where there are sharks – and this is true – but we may still have a concern in the back of our minds. So – we will give you some information that will hopefully enlighten you on the issue of sharks.
First, what kind of sharks are in the Gulf and how common are they?
According to Dr. Hoese and Dr. Moore from Texas A&M, there are 30 species of sharks who have been found in the Gulf of Mexico – and this includes the great white. They range in size from the Cuban Dogfish (3 ft.) to the whale shark (60 ft. in length). Each has their own niche. Some, like the large whale sharks, are plankton feeders. Others, like the blue and mako, are open ocean travelers covering large stretches of water hunting prey. Others, like the blacktip and spinner, are more common near shore – close to estuary outfalls where food is plentiful. And others still, like nurses sharks, are bottom dwellers feeding on slow fish and crustaceans.
The Bull Shark is considered one of the more dangerous sharks in the Gulf. This fish can enter freshwater but rarely swims far upstream. Photo: Florida Sea Grant
As far as how common they are – I was involved in shark tagging in the early 1980’s and we tagged several species. Blacktips and spinner sharks were very common. We also tagged a lot of bull and dusky sharks – though dusky sharks are declining. Tiger sharks were not as common at the time. It was believed this was due to an increase in shark rodeos in the 1970’s – which were popular during the “Jaws” films. However, those events stopped for several years and recent shark events have once again captured tigers. There are five species of hammerheads that were tagged – the scalloped and bonnethead were the most common. White sharks and makos are in the Gulf but were never tagged. It was believed they spent more time offshore (where we were not sampling). Both species have been seen closer to shore in recent years, but there are no reports of any problems from this. It is possible they have been doing this all along and were just undetected. Blacknose, finetooth, and silky sharks were also frequently tagged.
People are probably not surprised to hear that sharks frequent the bays. Many of the species mentioned above do so. The small (3 ft.) Atlantic sharpnose shark is one of the most common. Sawfish were once common in the estuaries but have declined significantly across the region to do over harvesting in the early 20th century. They are currently protected.
You have probably also read that bull sharks have been found in freshwater rivers – and this is the case. Some have been found several miles up river systems.
What type of prey do sharks prefer and how to do they select and hunt for them?
This, of course, varies from species to species. Plankton feeding whale sharks generally cruise slowly through the water column filtering small fish and crustaceans – the same as the great whales. They do tend to feeding in deeper water during the day and closer to the surface at night. They are following what is known as the Deep Scattering Layer. This is a large layer of zooplankton (animal plankton) that migrates each day – deeper (600 feet or so) during the daylight hours and closer to the surface in the evenings.
Bottom dwelling sharks feed on benthic creatures like flounder and crabs. Many have the ability to detect their prey buried beneath the sand using electric perception they have.
Many species of sharks are what we call “ram-jetters”. This means they do not have a pump system to pump water over their gills. So, in order to breath, they must swim forward. Swimming continuously requires a lot of energy. Most of them are what we call opportunistic feeders – meaning they will grab what they can. Stomach analysis of such sharks find primarily fish and squid, but other creatures have been found – such as birds and even other sharks. The general rule here is seek prey that is “easy”. If your objective in feeding were to obtain energy – it would not make since to chase prey that would require a lot of energy to catch. Simple first, and take opportunities when you can. It is the ram-jetter species that people are most concerned. Swimming and taking opportunities. However, evidence suggest that we are not a prey of choice, not good opportunities. More on this in a minute.
Tiger sharks are interesting. It is in their stomachs we find such things as hubcaps, metal, and other sorts of garbage. Because of their tooth design, they are also capable of eating sea turtles.
How often do shark attacks on humans actually occur and what were the people doing that may have enticed it to happen?
Records on human shark attacks are kept at the International Shark Attack File at the Florida Museum of Natural History in Gainesville, FL. This data set only logs unprovoked attacks – those where the people were doing their thing and all of a sudden… Not those where humans were pulling them into their boats after fishing or grabbing their tails while diving.
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
Based on this data – there have been 3031 unprovoked shark attacks reported worldwide since 1580 A.D. This equates to seven attacks / year. Granted… not all attacks are reported, particularly from the undeveloped regions of the world – and from early history, but it does give us something to look at.
Currently, we are averaging between 70 and 100 shark attacks worldwide and between 5-15 of these are fatal. Honestly, this is very low when compared to other activities in which humans participate.
||Deaths from Other
||Deaths from Shark Attacks
|1959 – 2010
||Lightning strikes – 1970
|2004 – 2013
||Rip Currents – 361
|2001 – 2013
||Dog bites – 364
|2000 – 2007
||Hunting accidents – 441
|2002 – 2013 (Florida only)
||Boating accidents – 782
As you can see… the risk is much lower.
It is true that most of the shark attacks worldwide are in the United States (46%) and that most in the U.S. are in Florida (56%). However, it is believed that this is due to the number of Americans (and Floridians) who enjoy water activities. In Florida, most of the encounters have been on the east coast – 89% of them! There have only been 65 attacks reported from the west coast – only 37 from the Florida panhandle – since 1580 A.D. There have only been six reported from Escambia County and one from Santa Rosa in that time.
As far as what people were doing when a shark attack occurred – most were surfing, but swimming has increased in recent years. This is believed to be connected to the increase in the number of humans swimming. The human population visiting beaches, particularly in the U.S., has increased significantly. Most shark attacks occur in near shore waters – which would make sense… that is where we are. Most are the “hit & run” version – meaning the shark hits the person and runs… not returning. Based on Florida reports, it is believed most of these are blacktips, spinners, and blacknose sharks. These rarely end in a fatality. “Bump & Bite” – meaning the shark circles, bumps the person, and then bites, are not as common. It is believed most of these are from great whites, tigers, and bull sharks. The few fatalities that happen are usually from this form of encounter.
When assessing “risk” in an activity you have to consider “control”. This means that the more you are in control of the situation, the less risky the activity seems to be. Most feel that in the water, the shark is in control – this increases our fear and risk concern. However, as mentioned in this article, many of the other activities we are involved – where we think we are in control – are far more risker than swimming on the open Gulf of Mexico.
However, shark attacks do occur and there are a few things swimmers can do to reduce their risk.
- Do not swim alone – all predators will try and isolate an individual from a group before they attack – much easier to attack an individual than a group
- Do not swim near dusk or after dark – to increase their chance of hunting success, sharks are more actively hunting in low light conditions
- Remove shiny objectives like jewelry – sunlight hitting metal objectives can appear to be baitfish to a shark
- Avoid blood in the water – it is true they have an excellent sense of smell – small amounts of blood in the water can be detected as far away as 100 feet suggesting easy prey nearby. Avoid swimming near fishing activity where bait and fish blood may be discharged into the water
I have been swimming in the Gulf all of my life. It is too much fun to worry about a low risk encounter with a shark. Follow the simple rules suggested by the ISAF and you should not have any problems.
The International Shark Attack File – https://www.floridamuseum.ufl.edu/shark-attacks/.
Hoese, H.D., R.H. Moore. 1977. Fishes of the Gulf of Mexico; Texas, Louisiana & Adjacent Waters. Texas A&M Press, College Station TX. pp. 327.
You might get that impression from the movies but if you look at the data you will see quite a different story. With nearly fifty species identified in the Gulf of Mexico, an encounter with a shark is eminent if you spend much time in our coastal waters. So, let’s get the “scary” stuff out of the way first and finish with the more interesting facts for our much-maligned “toothy” friends.
The Bull Shark is considered one of the more dangerous sharks in the Gulf. This fish can enter freshwater but rarely swims far upstream. Photo: Florida Sea Grant
The most recent data from the University of Florida’s International Shark Attack File shows that unprovoked attacks have occurred in 26 of Florida’s 35 coastal counties, from 1882 to present. Florida is the hotspot in the U.S. which makes sense with our 1,300-plus miles of coastline. Volusia County has recorded the most incidents at 299. Brevard County is second (144) and Palm Beach County third (75). Do you have any idea how many people have been in the water in these three counties since 1882? Let’s just say, a lot; if sharks were hunting for people, they would have found more of us by now.
In the coastal counties of the Florida Panhandle, numbers are much lower with Bay County having the most incidents at 9. Numbers drop from there with Escambia at 6, Okaloosa at 4, Gulf and Franklin at 2, Santa Rosa and Walton at 1 and none from Wakulla down through Pasco; remember, since 1882. Species most often involved have been bull or blacktip sharks (20% each), spinner at 16% and hammerhead at 13%. Believe it or not, the next highest is nurse sharks at 7%. Compared to drowning fatalities from 1992-2000, sharks loose, 2 to 135.
Okay, now for some more interesting facts about our Gulf of Mexico sharks. Some of you have heard about the encounter that Grayson Shepard (of Apalachicola) had with a great white back in 2015. If you want to see his amazing video visit this link. Even though great whites are considered a cold-water species, scientists have known for a long time that they do visit the Gulf of Mexico. Their incredible migratory nature has been studied in greater detail of-late. An 8.5 foot juvenile female that was radio-tagged off Hilton Head South Carolina travelled to Nova Scotia Canada before turning around and going south all the way around the tip of Florida and into the Gulf of Mexico. The most northerly “ping” picked up by the satellite receiver was north of Tampa on January 31, 2018. Savannah (her given name) is currently back on the east coast near where she was tagged by researchers. Vist this website to follow Savannah’s incredible journey.
The Great White shark.
Photo: UF IFAS
Another impressive shark species that occurs in our Gulf waters holds the title of “world’s largest fish!” Whale sharks can reach lengths of fifty feet and weigh around 20 metric tons. Most of the sightings in the Gulf have proven to be juveniles but occasional aggregations happen around abundant plankton resources. One chance encounter by scientists from the Mississippi-based Gulf Coast Research Laboratory, documented a large number of whale sharks feeding near the surface. Plankton samples revealed a rich concentration of fish eggs from recent spawning activity of little tunny and crevalle jack. Aggregations numbering near 150 individuals, feeding on abundant plankton, have been reported in the nutrient-rich waters near the Mississippi River drainage.
Sharks in the Northern Gulf of Mexico, just as alligators in our lakes and rivers, deserve our respect and a balanced conservation-minded attitude. They are an incredible resource that have vital connections to many other species in our marine environment. They are also one of the most thrilling creatures on the planet when you get to meet one up close. Just please use some good sense and mind those pearly-white teeth if you catch one on a line. Even a cute little wild mouse will bite you when handled but the outcome is slightly more concerning with sharks and alligators.
White Shark (Carcharhinus carcharias). Credit: Florida Sea Grant Stock Photo
From Fear to Fascination: White Sharks in the Florida Panhandle
UF/IFAS Extension – Florida Sea Grant
By Rick O’Connor (Escambia County) and L. Scott Jackson (Bay County)
Recently, I was walking on our local Gulf fishing pier checking fishing line recycle bins. You can’t walk on a Gulf pier without looking over to possibly catch a glimpse of a sea turtle or a shark, and I was not disappointed. It was hard to tell which species of shark but it was about 6 feet in length. It swam south along the edge of the pier and then east to make a large arching circle through the emerald water, past bathers at the surf break, and back to the pier only to swim the pattern again. Onlookers from out-of-town were giggling with delight to see the animal while a couple of local fishermen tried tossing bait at it, but most ignored it and went on with their fishing.
Bob Shipp’s book, Fishes of the Gulf of Mexico, lists 29 species of shark found locally. Most are members of the requiem shark family, such as blacktips and bulls, and hammerheads. Though these sharks are certainly capable of attacking humans, their presence usually does not interrupt water activities. Divers who encounter sharks may be startled at first but rarely do they end their dive or have problems with them. Even in 2005, remembered as the “summer of the shark attack”, few people stopped diving or surfing. Individuals have become educated regarding shark behavior and are not as startled when they see one. However, in 2015 there were several encounters with White Sharks.
Sightings in the Gulf of Mexico are rare but usually occur in the cooler months. Is the increased interaction with White Sharks unusual or something to worry about?
To answer this question I turned to George Burgess, a shark expert who manages the International Shark Attack File housed at the UF Florida Museum of Natural History.
Is this unusual?
Burgess assured me that White Sharks do occur in the Gulf of Mexico usually during cooler months and are transients, as opposed to residents. Their movement in and out of the Gulf is temperature driven. As late spring Gulf waters continue to warm into early summer, sighting a White Shark is less likely to occur. According to Burgess, White Sharks use deep water when traveling but prefer shallow water when hunting fish, turtles, and marine mammals. So, inshore encounters especially in cooler months would not be unusual.
Why is there a sudden increase in the numbers of encounters?
One part of the answer lies with the increased number of White Sharks. Conservation of sharks has been effective. Additionally, with the passing of the Marine Mammal Protection Act, there are more marine mammals, thus an increase in their predators, White Sharks. The other part is the number of humans visiting the northern Gulf has increased. There are more more visitors to marine waters, especially since the Deepwater Horizon oil spill. Everyone has a camera. Beachgoers, Swimmers, Divers, and Anglers all have improved technology to record their adventures.
Is Northwest Florida a “hot spot” for White Sharks? Burgess indicated that the northern Gulf of Mexico is more productive than the peninsular Florida due to the number of nutrient rich rivers in the region. Seeing more White Sharks here would not be any more unusual than finding more snapper, lionfish, or other species of shark. As far as worrying, there have been no records of White Shark attacks in the northern Gulf of Mexico since they began keeping records in 1872.
Finally, what does one do if they encounter a White Shark?
The quick answer is nothing different than with any other shark. It is true that most White Shark attacks occur at the surface but there are no records of any attacks in Florida. Burgess indicated that the Bull Shark is probably a bigger threat than the White Shark. For more information about Bull Sharks and general tips to avoid a negative shark encounter read this article http://nwdistrict.ifas.ufl.edu/nat/sharktips
In a recent video, recorded near Apalachicola, a diver was on an anchor line on a decompression stop when he saw a White Shark approaching from depth. What should a diver do in this situation? Should they swim for the surface and risk decompression sickness, remain still, or return to the bottom?
The answer has a lot to do with what the shark is actually doing. Is the shark interested in the diver or acting aggressively? Burgess suggests, you assess the situation and the shark’s behavior. All options are on the table and have to be weighed against the consequences given in this scenario. As a last resort, a diver may need to make a quick but graceful exit out of the water, past the shark, and depend on their diving partners to render aid as needed. The lesson is for divers to be prepared for a variety of potential issues on every dive.
For more information on sharks and shark attacks in Florida visit the International Shark Attack File at http://www.flmnh.ufl.edu/fish/Sharks/ISAF/ISAF.htm
Note: White Sharks are a protected and prohibited species. It’s illegal to beach or land them. See guidance on shark fishing regulations, gear requirements, Including catch and release methods from the Florida Fish and Wildlife Conservation Commission at http://myfwc.com/fishing/saltwater/recreational/sharks