While trolling one hot December morning off Vitoria, Brazil, my host noticed an approaching boat. "That captain loves to catch dorado," he said. "Watch what he does when he gets a little closer."

The newcomer nearly left skid marks on the waves as he screeched to a stop a quarter mile away from us. His excited voice came over the radio to ask how long we'd been fishing and how many dorado we had seen. The dolphin hunter couldn't wait to get lines in the water because he envisioned a banner day with the ideal conditions stretching out before him. We were working a wide weed line that extended for miles along a green-to-blue color change.

Weed lines provide cover for baitfish and represent a feeding trough for the ocean's predators. While dolphin usually top the list of hungry visitors, larger pelagics also answer the ringing dinner bell. On that day we set our sights on white marlin; three hours of trolling the blue side of that weed line produced six strikes and three releases.

Look for Life
Capt. Tony Murphy of Key Limey Charters (305-293-1814; www.keylimey.com) often encounters weed lines in the waters around Key West in spring and summer. "Our predominant summer winds come out of the southeast, while the Gulf Stream generally flows to the east. The current meets the southeast breeze and gathers floating material into weed lines," he says.

In the Mid-Atlantic region, Capt. Brynner Parks (252-473-1934; www.smokersportfishing.com) finds floating structure 30 to 40 miles out of North Carolina's Oregon Inlet. Vegetation carried by opposing forces — the south-flowing Labrador Current and the northbound Gulf Stream — forms lines when the wind cooperates. "A strong east or west wind blows across the currents, scattering grass and breaking up weed lines," he says.

Like paramedics arriving on the scene, both skippers check for vital signs as soon as they find a weed line. "Weed lines may be live or dead," Parks explains. "Live ones have grass that looks bright yellow, almost gold. That's a better sign than darker, brownish grass. Live weed lines usually have more baitfish and dolphin under them."

Murphy scans the water and sky before wetting a hook. "Many beautiful weed lines hold no fish," he says. "I like to see plenty of baitfish and activity under the weeds, along with birds working along the line. Don't waste hours trolling in a search for fish beside a dead weed line. And before you start trolling, take a good look around to make sure you're not going down the line behind another boat!"

Moving water makes a good weed line even better. "The perfect situation occurs when weeds gather along a rip. When I see that, I get a tingly feeling that something is about to happen," Murphy says.

Keep it Clean
Most weed lines have a clean side (with a well-defined edge) and a dirty side littered with loosely scattered weeds. Murphy stays on the clean side so he doesn't have to keep reeling in baits to remove debris. Also, dolphin often refuse to take baits fouled by vegetation.

Although Murphy prefers live-bait fishing from his 31 Contender, he always carries a few pre-rigged ballyhoo so he can begin trolling immediately upon finding a weed line to his liking. He follows the floating contours so one of the baits stays within 3 feet of the edge.

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