That timidity goes out the window when an energy-rich food source comes into view. The black triggerfish’s name belies its brilliantly ornate coloration. On any given dive, it’s common to see individuals laying on their sides, molding their 12-inch-long, oval-shaped bodies into shallow depressions in the volcanic rock, an apparent effort to blend into the background until the danger has passed. ![]() Sky-blue pinstripes delineate the fish’s ribbon-like fins, which propel them through the water with rhythmic flutters-a motion that brings to mind the flight pattern of a butterfly more than the aggressive tail swipes of a predator. While they often appear dark as pitch in low light, better illumination reveals a deep indigo interwoven with a complex pattern of olive green, light blue and gold as ornate as any Persian rug. Despite the name, they’re not actually black. Photos of their dense, dark schools made them look more like pests than attractions, but they’re really quite beautiful and fascinating. Having read about and seen dozens of pictures of blackfish before I came to Ascension, I didn’t expect to like or appreciate them as much as I do. And it’s just as common to see them grazing along the algae-covered bottom like herds of hungry goats.īlack triggerfish await the research team as they prepare for a dive at Ascension's Boatswain Bird Island. You can’t possibly go in or even near the waters of Ascension without seeing black triggerfish cruising the shallows in large, loosely organized groups waiting for a meal, any meal, to drift, swim or drop into their paths. Although the scientists aren’t entirely sure why the species has been so successful around these rocky outcrops, they think it’s probably a combination of the relatively low numbers of predators and competitors here, as well as the fish’s uncanny blend of omnivory and opportunism when it comes to food choice. Here, and around a few other isolated oceanic islands, they literally swarm. In most places, their numbers tend to be relatively modest. In the following video, a specimen intended for Rocha’s collection bag quickly becomes the focus of a massive feeding mob of black triggerfish (video by Steven Bedard):īlack triggerfish, or simply “blackfish” as the Ascension locals call them, are found in nearly every imaginable tropical reef habitat around the world. ![]() Even though the rest of the dive team carries nothing more than cameras and measuring tapes, the fish trail them, too, as they make their way back toward the beach. Fifteen minutes later, they haven’t given up. In his wake, a school of 30 or more black triggerfish ( Melichthys niger) mill around like a group of nervous, but hopeful, dogs at a barbecue as the last few snacks are packed away. “Sons o’ bitches,” he says with equal parts admiration and frustration as he fights his way through the surf and onto the narrow beach fringing this corner of Ascension Island's Comfortless Cove. After 45 minutes underwater, Rocha has had enough. This threat, though, is unrelenting, and the pursuers outnumber us by a wide margin. The Galápagos sharks that have followed our blood trail on earlier collecting dives are nowhere to be seen. It’s not sharks that Rocha’s worried about. ![]() Although there’s more sampling to be done and he still has plenty of air left in his tank, the scientist, a curator of ichthyology at the California Academy of Sciences, can’t afford to lose any more specimens. With his half-filled collection bag in tow, Luiz Rocha is high-tailing it out of the water. Now a team of scientific divers has taken the rare and brief opportunity to come to this rock in the middle of the Atlantic Ocean and study one of the most poorly understood marine communities in the world-to try to figure out where these fish come from, how long they’ve been here, and how they’re making a living in such isolation. While the number of fish here is astounding, surprisingly few species have been hardy enough and lucky enough to make the long journey and settle here successfully. Editor's note: There’s a fascinating natural experiment happening around Ascension Island.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |