Sometimes called "brown bomber," cobia prowl the flats off Key West in winter, often betrayed by cormorants. The behavior is occasionally seen in other parts of Florida.

Winter mornings, cobia forage along the rocks and guts of channel bottoms north of Key West. As the sun climbs, the shark-like brown fish move to the channel edges bordering the flats and wait for stingrays. When the rays swing up from the depths with their broad triangular wings, the cobia follow. Across clear, warm shallows, cobia chase crustaceans and baitfish the rays nose up out of the marl and sand bottom, as cormorants dive from the surface after the same prey.

The scene plays near Key West like a traveling circus act of the animal kingdom, with clumsy cormorants and determined cobia ganging up on the hard-working, harassed rays. It only happens a few weeks every winter though, while packs of cobia reside in the Lower Gulf before their spring migration north. With bad timing, anglers can miss it completely, but tracking the rays and cormorants to feeding cobia might be the sportiest pursuit on Lower Keys flats all winter.

“I’m sure if those rays had a gun they’d shoot the cormorants,” Phil Thompson says, “and probably the cobia, too.”

But the rays can only lead the cobia to us, as long as we have the smarts to figure out the pattern that brings the cobia to the flats in the first place. It’s not as easy as it sounds.

Phil found them the last Monday of January, and he and a few friends, all guides, went out on a busman’s holiday the next day and had a blast—eight cobia hooked, five boated, four released, all on fly. One guy would spot a ray mudding, go up and shut down his boat, and call the others if the ray held cobia. About a quarter of the rays were holding fish. Thompson and his friends had to pole to follow the ray with the wind, or else hold the boat off the ray if the wind blew them too close. When they hooked one, they followed the fight to the finish. Then they would find another mud and begin again.

“We had good size cobia, about 25 pounds,” Phil said. “Not the really big ones that we know are around, but good size.

Watching a cobia sprint across shallow bottom is a new experience.

“You don’t have to worry too much about spooking a cobia. It’s actually hard to get them off the ray,” he continued. “We made at least 10 casts to the ones we had out here before we hooked one of them. That’s why it’s great for a beginner fly caster. First, because he can see the ray, and the cobia often, too, and second, because he has a lot more time than with a permit, which will spook at the slightest move.”

That day, Phil actually broke off a cobia on fly that went right back to the ray. Then Phil cast to him again and the same cobia took the fly, and this time, Phil landed him. “They’re not shy,” Phil said. “I don’t know any other fish that will do that, twice in a row on fly.”

All that had been on a waning quarter moon and a high tide about 3 p.m, when the action got hot. The following day, another friend had five again, all on fly.

Phil and I made it out the next day. We were on the turtlegrass flats slightly north of Key West known as the Sea Plane Basin and Pearl Basin. At 9 a.m. the water temperature was 68 degrees.

“It will be about 72-74 degrees by 2 p.m.,” Phil says, “and slightly higher by the time the tide comes off this flat.”

Small jig sweetened with shrimp won't spook cobia.

We couldn’t confirm it until after a few more trips, but that water temperature near 72 degrees turned out to be the single most important factor in drawing the cobia up on the flats. Otherwise, we had a low tide at 11:30 a.m. and a 4-5:00 p.m. high tide, depending on place. The low was a moderate low, what Phil called a “hump tide,” for its subtle rise, much less than a spike. For bait we had shrimp-tipped jigs, live crabs and flies on 9-weight rods. We looked forward to holding by the cobia and sight-casting to them on the clear, 3-foot-deep flats. For fly patterns, use just about anything, Phil says. The action you give the fly is more important than the pattern.

“We had a hard time hooking up until we teased them into biting. You had to take it away and give it again. Use something bright and large that gets down a few feet quickly, like a big shrimp pattern with an epoxy head,” Phil said.