Sanibel Island is among the jewels of the Southwest Florida coast: a roughly 36-square-mile barrier island not plagued by overdevelopment, and indeed boasting plenty of fine natural subtropical habitat.
A beautiful swath of that habitat lies protected in Sanibel’s J.N. “Ding” Darling National Wildlife Refuge, occupying most of the island’s northern, mangrove-lined margin and host to better than 220 bird species.
Edged by Pine Island Sound to the north, San Carlos Bay to the northeast and east, and the wide-open Gulf of Mexico to the west and south, Sanibel (and its barrier-isle companion, Captiva) sits smack-dab in the midst of a very productive shark domain.
So if you’re wondering if Sanibel Island has sharks, the answer is Yes: A variety of shark species find rich hunting and nursery grounds in and around Sanibel Island. But that’s no cause for alarm!
The most common types of sharks found around Sanibel Island, FL are:
- Blacktip sharks
- Spinner sharks
- Lemon sharks
- Sandbar sharks
- Bull sharks
- Tiger sharks
- Bonnethead sharks
- Great hammerheads
- Nurse sharks
- And more
The good news is that Sanibel Island sharks aren’t bloodthirsty monsters, despite their Hollywood and media-fueled reputation.
Rather, they’re integral parts of the estuarine and marine ecosystems, regulating prey populations and performing other essential ecological services as the region’s top saltwater predators.
Outside of anglers, most visitors are unlikely to see a shark here; herons, egrets, wood storks, roseate spoonbills, and other waterbirds, plus alligators and manatees, are more frequent sights, though this is not to say that sharks aren’t abundant and widespread in local waters.
Let’s profile some of the more common shark species here, from laidback bottom-dwellers to fleet, flashy surf-hunters.
Types of Sharks at Sanibel Island
More than a dozen species of sharks occupy the coastal waters of Southwest Florida, from diminutive dogfish to the massive (and infamous) great white shark.
We’ll mainly be focusing on those species identified by the Sanibel-Captiva Conservation Foundation as the most common around the island.
The sturdy but sleek blacktip shark is one of the quintessential nearshore predators around Sanibel (and in much of Florida).
Maxing out at about eight feet, the blacktip embodies the typical form of the so-called “requiem sharks” (members of the carcharhinid family), with a broad, pointed snout, streamlined form, and asymmetrical caudal or tail fin, the top lobe being much longer than the bottom.
Blacktips dart their way around bays, estuaries, and nearshore ocean waters, hunting many kinds of baitfish; these hunts often bring them into surf right off the beach. They’re most common in summertime.
The spinner shark much resembles the blacktip and reaches about the same size, but a few subtle differences set these two carcharhinid relatives apart:
The spinner’s anal fin is tipped in black, unlike (a little ironically) the blacktip’s, and the spinner’s first dorsal fin is set slightly farther back on the body—behind the pectoral fin.
Spinners come by their name honestly: In exuberant pursuit of baitfish, they commonly corkscrew clear out of the water at high speeds.
The lemon shark, another requiem shark, is every so slightly flattened-looking, and as its name suggests its hide is a bit yellowish in hue.
Another characteristic feature of the species is the first and second dorsal fins being close to the same size.
Lemon sharks are common in inshore waters, occasionally hunting river mouths; mainly a tropical species, they head into deeper waters or southward during the winter. Young lemon sharks (pups) find refuge in mangrove swamps and shallow seagrass flats.
Full-grown lemon sharks enjoy a diverse diet including various fish, crabs, and even the odd seabird.
Growing to roughly the same size as blacktips and spinners, sandbar sharks are less often seen right along the shores of Sanibel, but do occasionally hunt in bays and estuaries.
This brownish shark’s most striking feature is its tall, sail-like first dorsal fin. Sandbar sharks often hunt along the seafloor, looking to seize rays, skates, smaller sharks, octopi, squid, and the like.
The bull shark roughly resembles, say, a blacktip or sandbar shark, only majorly beefed up.
Bull sharks are brawny, thick-looking carcharhinids with heavy jaws and robust teeth.
Usually 10 feet or less in length, bull sharks nonetheless may grow to at least 13 feet.
Preying on everything from bony fish, rays, and other sharks to dolphins and seabirds, bull sharks are well known for their freshwater tolerance; common in tidal rivers and estuaries, they may swim long distances upstream.
Tiger sharks are the largest of all the requiem sharks, capable of reaching lengths of 18 feet and perhaps more.
Named for the dorsal stripes that fade some with age, the tiger shark boasts an impressively wide set of jaws packed with serrated, asymmetrically curved teeth capable of sawing through the carapaces of sea turtles (a favored prey item).
Like bull sharks, tiger sharks are top predators of Southwest Florida’s estuaries, bays, and inlets.
They pursue a legendarily undiscriminating diet: besides turtles, also spiny lobsters, crabs, bony fish, rays, other sharks, seabirds, offal, and marine mammals such as dolphins and manatees.
(In various parts of the world, tiger-shark stomachs have yielded everything from tin cans and automobile tires to domestic animals and crocodiles.)
Of the several hammerhead-shark species found in Southwest Florida waters, the bonnethead is the most readily seen—and by far the littlest.
Possessing a more tightly curved, shovel-like head compared with the classic hammerhead design, the bonnethead grows to a maximum length of a mere five feet.
Bonnetheads are common in inshore estuarine waters and nearshore surf, where they snack heavily on crabs. They’re also the only known species of shark to regularly ingest plant matter—seagrasses, to be specific.
Their small size makes bonnetheads vulnerable to a variety of predators, from other sharks and groupers to alligators and even ospreys.
At the other end of the hammerhead size spectrum from the bonnethead, the great hammerhead is the biggest of its kind: sometimes 20 feet or so from flattened snout to tail-tip.
This magnificent beast cruises reef drop-offs, seagrass flats, and other continental-shelf habitats, and also periodically enters bays and passes.
Defined equally by its hammer-shaped head and its tall, ramrod first dorsal fin, the great hammerhead may take a wide variety of sealife as a meal, but it’s particularly fond of stingrays.
Occasionally spotted by snorkelers and divers off Southwest Florida, nurse sharks are among the most distinctive inhabitants of regional reefs and (especially when young) mangrove communities.
A tawny, good-sized shark capable reaching lengths of 12 to 14 feet in rare cases, the nurse shark sports distinctive barbels on its snout, a regally long tail fin, and a first dorsal fin set well back on the body.
While often seen during the day resting motionless on the bottom, nurse sharks are active reef hunters foraging for sea urchins, crabs, lobsters, octopi, and other bottom-dwelling prey.
Other Sanibel Island Sharks
Among the other shark species found in Sanibel’s general vicinity are several other carcharhinids, including the small and slender blacknose shark and the much heftier dusky shark.
Another requiem shark, the oceanic whitetip, was once extremely abundant in pelagic waters of the Gulf of Mexico (and more broadly across the World Ocean’s tropical and subtropical reaches), but its population here, as in many other parts of its vast range, has collapsed drastically due to overfishing.
Other more pelagic Gulf sharks include makos—the speedsters of the shark world—and threshers with their almost cartoonishly long caudal fins.
Great white sharks, which may reach 20 or more feet and weigh better than two tons, have also been tracked into the offshore waters of Southwest Florida.
The snaggle-toothed sand tiger shark hovers around reefs and wrecks.
Smooth and scalloped hammerheads are relatives of the bonnethead and great hammerhead also found locally.
Besides bonnetheads and blacknoses, other common little sharks in the region include the smooth dogfish and chain catshark.
Shark Attack History at Sanibel Island
If a fear of Sanibel Island sharks has kept you out of the water during your getaway here, allow us to quell that anxiety a bit.
Sanibel has seen a mere eight—yep, eight—officially confirmed shark attacks, and none of them have been fatal.
And, as the Sanibel-Captiva Conservation Foundation notes, a significant share of these bites were pretty clearly defensive responses on the part of the fish.
For example, the first documented attack on Sanibel Island, which dates to 1958, involved a man stepping on a shark—in fact, as he described it, stepping into its mouth—which may have been resting on a sandbar.
The most recent known sharkbite from Sanibel, from 2013, involved a 17-year-old who was fishing in waist-deep water on a sandbar; a shark, later theorized to be a six- to eight-foot-long bull shark possibly attracted by bait in the teen’s pocket, bit him on the shin and ankle, resulting in minor injuries.
Perhaps the most serious shark attack recorded on Sanibel took place in 1986, when a six-year-old girl was bitten on her upper leg by what was reckoned to be a five- to eight-foot-long lemon shark. She survived and regained most of her leg function. As in the 1958 sharkbite, the victim had actually stepped on the shark.
The Sanibel-Captiva Conservation Foundation further observes that the broader Southwest Florida coast around Sanibel Island has never experienced a documented fatal shark attack.
Many of the other attacks in the region also suggest either defensive bites or sharks aroused by angling.
Nips to swimmers (and surfers) account for many of the shark attacks in the Sunshine State, and are thought to primarily result when small to midsize sharks such as blacktips or spinners that are hunting close to the beachfront mistake a moving human hand or foot for the baitfish they’re after.
Florida “boasts” by far the largest number of confirmed shark attacks in the U.S., with 868 recorded since 1837. Compare that total with those for the states with the next-highest tallies of shark attacks: Hawaii at 176 and California at 129.
But the vast, vast majority of those attacks have been fairly minor bites; only 36 of them were fatal. And your odds of being attacked by a shark to any degree are less than being struck by lightning, savaged by a dog, hit by a car—or, certainly, of drowning, a much more front-and-center danger to Sanibel Island beachgoers.
According to the Florida Museum’s International Shark Attack File, requiem sharks account for most attacks on people in the state, though, unsurprisingly, the exact species often goes unidentified.
Of the incidents wherein the attacking species was pegged, most involved bull sharks, followed closely by blacktips.
Based on size and disposition alone, the most dangerous sharks regularly encountered in Sanibel waters are bull and tiger sharks, though the great hammerhead—while not as aggressive as those two species—is worthy of mention given its impressive proportions.
Of the six most recent fatal shark attacks in the state of Florida (occurring in 2010, 2005, 2000, 1998, and 1995), bull sharks were pinpointed as the likely culprit in five, while a tiger shark was responsible for the ‘98 incident.
Before you go, one quick note on the infamous white sharks, which are not particularly common in this region.
While disposed as adults to prey on creatures as big or bigger than humans—including pinnipeds, small to medium-sized cetaceans, and large fish such as tuna and billfish—great whites are thought to most frequently attack people due to mistaken identity.
And we’ll note that there’s never been a confirmed attack by a white shark in Florida, though the species is definitely present here, at least on a seasonal basis.
(While you’re here, learn about jellyfish in Sanibel Island.)
Avoiding Shark Attacks at Sanibel Island (Tips & Things to Know)
There are many common-sense measures you can take to minimize the chance you’ll have an unpleasant encounter with a shark during your Sanibel Island idyll.
And let’s underscore the fact that said chance is a low one to begin with.
Drawing on the slim history of shark attacks on this barrier island, you might first and foremost watch where you step while wading, and take extra precaution when fishing, given sharks may be drawn in by bait and blood, or targeting the same fish you are at the same time.
Here are a few other fundamentals of Sanibel Island shark safety:
- Don’t swim, snorkel, or surf alone: Pursuing these and others water activities with others (a) may discourage a shark from tangling with you and (b) puts more helping hands on the scene in the unlikely event of an attack.
- Avoid swimming in areas where baitfish are congregating—which may be indirectly evidenced by diving seabirds or circling dolphins—and where fishing boats or shore-bound anglers are at work.
- Don’t swim at dawn, dusk, or nighttime, periods when sharks are generally more active.
- Avoid wearing shiny jewelry in the water: A shark may confuse its glint for glittery fish scales.
- Be particularly cautious around sandbar or reef drop-offs, classic places for large sharks to prowl.
Sharks are a precious and awe-inspiring component of Sanibel Island’s underwater ecosystem.
In Sanibel, as with most beaches in the United States, there’s no need to be afraid of these ancient and beautiful fish.
If sharks were more prone to targeting people as prey, they’d be terrifying animals indeed—but they simply aren’t, as the statistics support.
Treat sharks and their environment with respect, stay aware and alert, and avoid reckless behavior while swimming, snorkeling, boating, and fishing, and you’re highly unlikely to be on the receiving end of those splendidly fierce teeth.
For more, don’t miss:
- Guide to sharks in Tybee Island
- Guide to sharks in Hilton Head
- Guide to sharks in Topsail Island
- Guide to sharks in Malibu
- Guide to sharks in Panama City Beach
Hope this helps!