Researchers have now documented the first known occurrences of white sharks ( Carcharodon carcharias ) in the Flower Garden Banks National Marine Sanctuary and surrounding outer continental shelf ecosystem, suggesting that a network of offshore reefs may form part of a seasonal migration corridor for white sharks traveling thousands of kilometers across the western North Atlantic.

Flower Garden Banks National Marine Sanctuary, or FGBNMS, lies just over half-a-mile (roughly 200 kilometers) offshore in the northwestern Gulf of Mexico. Its 17 banks rise from the surrounding seafloor, creating patches of hard-bottom habitat in a region where such habitat is relatively scarce. Many of these hard-bottom habitats in turn support coral, sponge and other invertebrate communities, along with the fishes that depend on them. The waters around the banks also attract highly mobile predators including sharks, tunas and billfishes. This unexpected underwater metropolis has been monitored by scientists for more than 35 years of observations. But white sharks had never been documented there through visual or remotely operated vehicle surveys.

Between 2022 and 2025, a large acoustic receiver array was deployed across the sanctuary and surrounding outer shelf. Thirty-two receivers were positioned at natural banks, artificial reefs and other sites. Meanwhile, white sharks had already been fitted with acoustic transmitters elsewhere along the eastern coast of North America, from South Carolina to New Brunswick, Canada. When one of those tagged sharks passed close enough to a receiver, the instrument recorded its unique acoustic signal. Nine white sharks eventually appeared in the data from the Gulf. They had originally been tagged as far away as Massachusetts and South Carolina, with some traveling more than 2,299 miles (3,700 kilometers) from their tagging locations to reach the outer shelf of the northwestern Gulf.

And it turns out that these sharks were not simply passing through one random patch of ocean! Five individuals were detected at seven different banks within the sanctuary, including East Flower Garden, Horseshoe, Bright, Geyer, Rezak, Sidner and Alderdice. Others were detected at surrounding banks and artificial reefs, including areas associated with shipwrecks and oil and gas platforms. The timing of their visits were also intriguing; white sharks were detected between January and August, with most observations occurring during spring and summer. Their visits were generally brief and no individual remained at a single receiver site for more than a day, suggesting these reefs may function less like a destination and more like stepping stones along a much larger journey.

That possibility fits with what scientists already know about white shark migrations: in the western North Atlantic, these sharks move between northern waters and the southeastern United States and Gulf of Mexico. Their movements can span thousands of miles/kilometers, and the timing of their southern migrations overlaps with seasonal changes in temperature and prey availability. This means the Gulf may be more than an occasional stopover. It seems like its outer shelf banks could be acting as important waypoints in a migration corridor, particularly during periods when prey such as reef and pelagic fishes aggregate around these structures. The timing also overlaps with the seasonal movements of other large predators and migratory fishes, including bluefin tuna, although the researchers caution that a direct relationship between those migrations has not been established.

For an animal capable of crossing an ocean basin, it certainly raises eyebrows when they keep coming back to a specific area, though. Two white sharks, one male and one female, were detected in the Gulf across multiple years and returned during roughly the same seasons. One male was detected during spring in three successive years. Another female returned during summer in two consecutive years. The male’s annual journey between the Gulf of St. Lawrence and Flower Garden Banks amounted to at least 5,717 miles (9,200 kilometers) each year. Repeatedly returning to the same offshore region raises fascinating questions. What really brings these sharks back — are they following predictable concentrations of prey? Are environmental conditions acting as navigational cues? And if a white shark only spends a day at a particular reef, does that reef still matter?

Probably, is the answer to that last question. For highly migratory animals like white sharks, protecting individual places matters, but so does understanding how those places connect. That is where acoustic telemetry becomes particularly powerful. The white sharks were not tagged specifically because researchers expected them to visit Flower Garden Banks! The receivers were simply there, listening as part of a broader effort to understand ecosystem connectivity. The sharks revealed themselves because scientists had built the infrastructure to hear them.

The Gulf of Mexico has long been treated as part of the white shark’s broader migration story, but these detections add another chapter to what is turning out to be a fascinating book of the region. It seems that beneath the surface, those offshore reefs may be more connected than they appear on a map, linking distant parts of a shark’s enormous seasonal range. The next challenge is figuring out exactly what brings these giants back and how we can protect the routes they use to get there.