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Rigs, Towers, FADs & Sinkhole Hunting

My first dives on intact and active oil rigs came during the 2002 Alabama Open Spearfishing Rodeo, about 60 miles offshore from Gautier, Mississippi. Rigs are amazing vertical coral reefs, with more fish than I’ve ever seen in any one place, especially big pelagic and reef fish! (All divers should have rig dives high on their bucket lists!)  

Every continent in the world has oil and gas rigs, and according to Rigs to Reefs, in the USA there are over 4,500 offshore rigs from Alabama through Texas in the Gulf of Mexico, and 27 in the Pacific Ocean offshore from California. 420 former oil rig platforms have been decommissioned and converted into permanent artificial reefs, as of September 2012. Most commonly they are left in place after toppling or partial removal below safe navigational depths. Sometimes they are towed and placed elsewhere, as were three donated by Tenneco in the early to middle eighties and placed in Pensacola, Apalachicola and Fort Lauderdale. I videotaped the Tenneco Towers in Lauderdale in the nineties, in about 110ft, with relief of nearly 50 ft. They are a few of the largest artificial reefs in the USA. They are great dives, composed of the tower frame, with legs, horizontal and diagonal cross beams, and stairways, all heavily overgrown in coral, gorgonians, and sponges. Several scuba divers with tiny guns were chasing amberjacks around but didn’t shoot anything. Goliath groupers were all around the bottom, and I saw one black grouper take off to the other much deeper towers to the east. I’ve got to dive those towers!

Offshore Jack Up Rig in The Middle of The Sea at Sunset
Offshore Jack Up Rig in The Middle of The Sea at Sunset

Most of the active rigs I’ve dove from Alabama, Louisiana, and Texas were conventionally fixed rigs, which had the same type of structure as the Tenneco Towers, but also included clusters of vertical interior pipes, huge docking decks near the surface, and frequently, a few extra towers attached or in close swimming distance. The biggest rigs are multiple combined towers, sometimes connected with walkways on their highest decks. Usually, good spearfishing begins 40 to 80 nautical miles offshore, in 330ft / 100m or much deeper. Even that far out, mirk layers from “Big Muddy”, AKA the Mississippi River, make visibility a challenge. It’s either green and cloudy on the surface, but clear 30 feet below, or the other way around. In 4 years diving with the Hell Divers Club in their Rodeos, I only saw the bottom on 2 dives, well west in Texas where it gets shallower. The smallest rigs are nicknamed “Lemon Trees,” by the Hell Divers because they have single trunks above water, and always seem to have lots of lemon-fish, (or cobia.) These little rigs still have extensive legs branching out with lots of beams below, and many interior pipes as well.

Rigs often have current, so to avoid being swept off the rig you need to hang inside between the legs, or at least keep them in sight. A new thing I learned quickly, is that rig legs spread out right away, so don’t bother swimming to the rig on the surface, just descend straight down from the boat, and you’ll end up near a rig leg.

With all this vertical structure, it’s little wonder there are so many big fish on rigs. Red snapper is the most prestigious fish in the North Central Gulf. They are very smart and sound quickly on the rig legs. Sometimes reds and other fish will follow scuba bubbles shimmering to the surface, so roll over and look up often! I’ve never seen such huge schools of mangrove snappers, buzzing around the waterline decks. I had a double head-shot once, stoning one 12-pounder, and unknowingly, hitting a 7-pounder behind him! Sixty-plus pound gag grouper, record-sized scamp, and massive Warsaw grouper, often rise along the pipes from very deep to shallower water, so divers need to keep watch on the center pipe clusters. (Black groupers don’t range past north-central Florida waters.) There are always lots of big cobia around rigs, commonly at the surface when you enter. Remember these fish love to play possum when shot, and go berserk when a diver touches the spear. Amberjack just under or just over 100lbs are common, and almaco jacks are not so rare on rigs either. The Hell Divers showed me an amazing local rigging method for spearguns, called a “Riding Rig, but nobody seems to remember who invented it! It’s mostly used by scuba shooters, but I occasionally used it skin diving. A riding rig is much like a bluewater rig, because when you pull the trigger the gun is no longer attached, and the diver shoulders it by running one arm through a band. Uniquely different is that the end of the cable or spectra shooting line is crimped to a short segment of rope, about the length from the gun handle to the front line-wrap near the muzzle. The 3/8” or ½” rope is easy to hold onto, like in a western rodeo on land! The rope is held in a manner that does not loop over the hand, for safety reasons, and a large brass or SS clip is looped onto the end of the rope. If the diver is getting towed down, he can wrap it on a piece of the rig and clip it back to itself, and ascend high above to watch while the fish tires and bleeds out. The riding rope is also used to pull the muzzle in any direction before taking a shot. Back at the boat, the rope is handed to a buddy who hoists the fish aboard, while the diver deals with the rest his gear. A buddy of mine, Jim (Chiefy) Mathie, wrote a spearfishing book called “Catching the Spear-it!”, for which I contributed some fish & diver photos. To my surprise, he printed 3 pages of photos of my Riding Rigged speargun! Having not returned to the rigs in years, I switched the riding rig to my Bluewater Lite speargun, and the length matched it perfectly after unlooping the brass clip and attaching a shackle directly to my float line, with a bungee breakaway. If I get a rig trip in the future I can easily switch it back to the riding rig gun.

amberjack school in the blue
amberjack school in the blue

Towers come in many sizes, from shallow navigational light towers, which usually attract a few barracuda and little else, to some big ones like those in the Gulf of Mexico, southwest of Naples, FL and running down almost to Key West, or farther just north of the Dry Tortugas. My first tower dive was on a run to the Tortugas, and nobody wanted to stop for it, so I solo freedove it, shooting a 10lbs mangrove snapper, with one leg still in the air! Everybody then raced getting dressed. There are 7 of these Department of Defense, Airforce Relay Towers, which are close to the size of a Lemon Tree Rigs, but one of my Hell Diver buddies who dove one said, “That ain’t even close to a rig son, that’s just a pole!” I’ve hit all but 2 of them, and they all branch out to 4 legged towers with horizontal & diagonal crossbeams, just no interior pipes, and just 100ft / 30m tall, and only in 65ft /20m to 125ft / 38m of water. Visibility is usually good and they have lots of amberjacks, permit African Pompano, so my Riding Rig gun works well there, as well would the Bluewater Lite rigging. Where these towers stand, the bottom is often littered with pieces of metal from the tower, as well as some broken limestone ledges that attract good-sized gag and black grouper. Soon I’ll run a Towers and Wrecks trip to SW FL, and hopefully hit the 2 towers I’ve missed. Then maybe I’ll head northwest to Apalachicola, in the Big Bend area of Florida, where they have 5 more towers, most of them standing inside barges.

Fish Aggregation Devices, FADs, are usually just buoys attached to the bottom in an area where the chain and anything attached to it will collect marine growth, which attracts bait, which draws pelagic fish. Many weather buoys or commercial shipping moorings unintentionally became FADs. In places like Hawaii, with deep bluewater they work great, but in other places, not so well. Many years ago, I dove NOAA’s NDBC Buoy 42036, a few miles from a very fishy area called the Florida Middle Grounds. The surface waters were barren, as was the bottom in 165ft / 50m of water. Conversely, divers and fishermen have a history of fishing weed lines in the Atlantic, very successfully for dolphin and tripletail. A floating pallet or other debris enhances the action much more. Some people argue that FADs should be stopped, because they aggregate fish, and make spearfishing too easy. If they ever bluewater spearfished they wouldn’t say it’s easy. Many say that about artificial reefs as well, even though they are proven to increase fish habitat, and relieve fishing pressure on natural reefs.

As in all spearfishing areas with a structure at or near the surface, divers should avoid entanglement, and use gear that does not easily get cut off but carry knives and cable cutters for safety reasons.

Sinkholes are found way offshore from St. Petersburg, FL, that drop straight down from sandy bottoms around 130ft/ 40m deep, into barren limestone holes 200ft /61m or deeper. Sinkholes are the reverse of rising vertical structure but similarly attract many pelagic fish in the waters above. Very few Gulf sinkholes have grouper or snapper on the bottom because they have little-broken rubble or tight ledges to interest them. Blue holes in the Bahamas are very different, sometimes with extensive coral reefs around them. Two I dove in the Cay Sal Banks were loaded with big black groupers and hogfish, which can be shot freediving with primitive polespears or slings. I do not remember seeing jacks or other pelagic fish there.

Like FADs, freedivers or scuba divers, that spearfish on sinkholes need to watch out for entanglement. One of the St Pete sinkholes is named Russ’s Sink, not because he found the site, but because he drowns there, wrapped in his cable shooting line and a vertical cable he used to float big amberjacks to the surface. I recommend stainless steel EMT sheers, now called Sea-snips, for cutting away cable or spectra shooting lines or fishing tackle. Always dive with a sharp stiletto knife as well.

Dive and spearfish with care!

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Chad Carney
Chad Carney
Capt. Chad Carney - Lifetime diving and spearfishing instructor.