Stan Ulanski: A Floating Jungle: The Sargassum Community

Today we welcome a guest post from Stan Ulanski, who teaches us how sargassum is like its own ecosystem within the ocean.  The various organisms attract many species of fish, which in turn draw anglers to these “floating jungles.”  A federal law now regulates sargassum habitats to protect these many species.  To learn more, check out Ulanski’s new book, Fishing North Carolina’s Outer Banks: The Complete Guide to Catching More Fish from Surf, Pier, Sound, and Ocean, now available. -Alex

Knowledgeable anglers are keenly cognizant of the fact that habitat plays a key role in fishing success. Spotted seatrout prefer holes or depressions where they can corral baitfish, which do not have much chance of escape. Sheepshead are notoriously structure oriented; they hold close to pilings of the pier, where they remain in the shade of the structure and dine on the attached organisms. But in Neptune’s realm, the vast expanse of the offshore region, there is very little visible habitat, only any endless horizon of blue water. But periodically and sporadically oases of life can be found: lines or patches of sargassum weed.

The drifting sargassum is actually a brown algae, which gets its name from the pea-size floats, containing a mixture of mostly oxygen, nitrogen, and carbon dioxide, which provides for its buoyancy. As Portuguese sailors journeyed to the New World, they christened the floating raft of weed salgazo because the tiny floats brought to mind a small grape found in their homeland.

Pelagic sargassum supports a diverse assemblage of organisms, including fungi, micro- and macro-epiphytes (plants that grow on other plants), and dozens upon dozens of invertebrates, fish, eels, and turtles. This web of life comprises a “floating jungle.” The high diversity of organisms, dependent upon this marine jungle, may be the result of a number of factors: protection, shade, feeding opportunity, and use of spawning substrates. With its tangled maze of stems, fronds, and floats, sargassum provides a perfect shelter for small fish to take up residence. But wherever there is a concentration of prey, hungry predators make their presence known, ready to play their role in the marine food chain.

Anglers, who routinely head out to the offshore waters from the myriad marinas strung out along the Outer Banks, are keenly aware of the attraction of sargassum weed for Gulf Stream gamefish. Dolphin (or dolphinfish) have a particular affinity to sargassum weed. Attracted to the smorgasbord of marine organisms that inhabit the sargassum, dozens of dolphin may be found holding just below even the smallest clumps of sargassum. When a school of dolphin is located, anglers use cut bait, such as squid, on light tackle. With reels in free spool, the baited hooks are played out behind the boat. Dolphin are aggressive feeders and will literally hook themselves.

If dolphin are not sighted, anglers will troll ballyhoo on twenty- to fifty-pound tackle along sargassum weed lines. The skipping bait often elicits a strike from a big male dolphin that charges out from the beneath sargassum to engulf the angler’s offering.

Because of the unique assemblage of organisms within the sargassum community, which attracts predatory game fish, the South Atlantic Fishery Management Council (SAFMC), the federal agency responsible for protecting pelagic fish and their habitat from North Carolina to Florida, has declared sargassum as “essential fish habitat” and is charged by law with minimizing any adverse effects on such habitat. In 2003, SAFMC developed and implemented the Sargassum Management Plan, which places strict limits on the harvesting of sargassum within 100 miles of the coast.

Stan Ulanski is professor of geology and environmental science at James Madison University. He is author of Fishing North Carolina’s Outer Banks: The Complete Guide to Catching More Fish from Surf, Pier, Sound, and Ocean and The Gulf Stream: Tiny Plankton, Giant Bluefin, and the Amazing Story of the Powerful River in the Atlantic. He is a passionate angler who has fished all along the Atlantic and Gulf coasts.