On August 13, the crew members of Gulf Magic, a charter fishing boat based in Port Aransas, had just decided to move from their fishing spot near an oil platform about six miles offshore from Port A. They were in about fifty feet of water when Captain Addison Smith saw an unusually large dark shadow. It was just an instant before he and his friend and crewmate Alexus Broome realized they’d been paid a visit by the biggest fish in the world: a whale shark. This one, whose length the sailors estimated as 20 to 25 feet, was probably an immature male that might one day nearly triple that size, maxing out at 62 feet long and forty tons. No one knows exactly how long whale sharks can live, but estimates range from 80 to 130 years.
Recognizing their luck, Smith and Broome quickly dropped an underwater camera beneath the surface and captured footage of the animal’s fluid swimming, offering a rare close-up of its striking spotted coloration, which looks like white planets embedded in a deep blue sky. In the brief video clip, which went viral on TikTok, a dozen or so smaller fish tag along, like groupies following a rock star. For a moment, the frame is filled by two cobia and a few remora, or shark suckers—species that shadow whales and sharks in a mutualistic relationship, snacking on small parasites. Then the world turns to bubbles just before the behemoth dives, the whole encounter just 22 seconds of magic.
Smith told Texas Monthly he’s fished the Gulf his entire life and worked as a recreational fishing captain for the last six years, but he had never before seen a whale shark, much less one so close to shore. “I only wished I would have jumped in and swam with it,” he said. It’s fine to swim with whale sharks, which aren’t a danger to humans, as long as you keep your distance to keep the animal safe. Smith described the sighting as “a bucket list moment.”
Seeing a whale shark so close to Texas shores isn’t unprecedented—a similar sighting near Port Mansfield made news in 2019, for example—but it is rare and thrilling. Whale sharks typically prefer deeper, warmer waters; in tropical destinations such as Cabo San Lucas, Mexico, and Roatan, Honduras, tourists sign up for boat tours that promise a chance to swim alongside the gentle giants. From a research vessel out in the Gulf, where he was doing bottom longline surveys of fish and sharks, NOAA fisheries biologist Eric Hoffmayer shared Smith and Broome’s enthusiasm. “It’s really cool to hear about this type of encounter, especially in areas where they aren’t typically seen that close to shore,” he said.
In 2021, Hoffmayer and his colleagues published the largest study of whale sharks in the northern Gulf of Mexico, including a database of 822 sightings made between 1989 and 2016 from boats and oil platforms. Most whale sharks were reported along the continental shelf and slope between the western Florida Panhandle and Corpus Christi.
The sightings revealed that the whale sharks were common near the mouth of the Mississippi River, where nutrients form the basis for a rich community of plankton—a whale shark’s primary food source. Rather than pointed faces and trident-shaped teeth stereotypical of sharks, whale sharks have wide mouths that give them their whalelike look and allow them to Hoover up vast quantities of food. Inside the mouth, twenty meshy filter pads sieve out plankton.
Hoffmayer’s research found that an area called Ewing Bank, off Louisiana, proved especially popular with whale sharks in the summer. There the species is often associated with a fish called little tunny, or bonito. Little tunny release eggs every few days, and the whale sharks arrive during the release and then disperse. The next time little tunny release eggs, the whale sharks return again. “I’ve been out there with a hundred animals at a time,” Hoffmayer said.
Feeding is part of the reason for these aggregations, but their exact nature is unclear. The groups tend to be made up of immature males, like the kind Smith and Broome saw. But why the groups are mostly young males remains an unanswered question, as does much about the life history of the mature animals, which tend to be solitary and nomadic. “The really big females are a mystery,” Hoffmayer said. “It’s like the Holy Grail when you do find one.” No one knows, for example, where or when whale sharks mate or have their young. No one has ever reported seeing a pregnant female in the Gulf of Mexico.
To reveal more about the secret lives of these indisputably charismatic creatures, Hoffmayer and his colleagues attached satellite tags at the bases of the dorsal fins of 48 whale sharks between 2008 and 2014. The tags stayed on the animals anywhere from a few days to a year. Some trends emerged: The whale sharks cruised up to 32 miles per day, with an average of 12 miles. They spent the summers nearer to the surface and closer to the continental shelf and tended to move to the south and into deeper water during the winter.
But collectively, the satellite tracks looked a lot like a plate of spaghetti dumped onto the Gulf of Mexico until Hoffmayer mapped them along with oceanographic features called warm-core eddies. The dominant current in the Gulf, the Loop Current, regularly sheds these circular currents hundreds of miles in diameter. The eddies’ spin pulls nutrient-rich deep water up toward the sunlit surface and creates conditions under which plankton prosper. The whale sharks appeared to capitalize on these complex dynamics. Their satellite tracks were associated with the eddies where the plankton they eat were likely abundant.
Whale shark scientists are also using advanced computational methods to gain more knowledge about individual animals. The galaxy of white spots on a whale shark’s skin is one of a kind, like a human fingerprint. Sharkbook is a blended citizen-science and research program that catalogs imagery of whale sharks. Once someone uploads a photo or video of a whale shark, the software, which uses algorithms similar to those employed by NASA to spot new planets, then tries to distinguish individual animals. Machine learning further enhances the identification system, which contains individual identifications for 120 whale sharks from the northern Gulf and about 2,000 from the southern Gulf. (Estimates of the total global population range from 128,000 to 200,000.)
An ideal photo for Sharkbook’s analysis is of the area behind the gills on the left side of the animal, taken at a 90-degree angle to its body. By chance, Smith and Broome’s stunning video captured the whale shark’s right side. Nonetheless, at Hoffmayer’s urging, they submitted the footage to the database. No match has been found, yet. Perhaps when someone else sees the same animal and submits data from both its left and right flanks, we’ll learn more about the intrepid giant that ventured into Lone Star waters. Hoffmayer also encourages anyone who sees a whale shark to submit the sighting to a database at the University of Southern Mississippi, even if they are unable to capture images.
While advancing scientific understanding is important, Hoffmayer agrees that seeing a whale shark is about more than just data. “It’s a life-altering experience for most folks to see an animal that big, to look eye to eye with these guys,” he says. “Most people don’t know they occur in the Gulf, so when they do come closer to shore, hopefully it increases awareness for folks. They’re such amazing creatures.”
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