Off the coast of Grand Isle, Louisiana, “Cajun Coral” – a highly customizable type of 3D-printed concrete – is slowly attracting sea life. 

Late this summer, a barge brought 500 pieces of Cajun Coral just east of the Barataria Waterway, which connects the Gulf of Mexico and Grand Isle to Lafitte and New Orleans. The coral modules, each weighing more than 400 pounds, were placed into the waterway individually by crane to encourage the growth of more than 10,000 square feet of living reef. 

The new reef was built on a former oil and gas platform called Hotel Sid that once stood in these waters.

In Grand Isle, a fishing town situated on a small barrier island, fishermen favored the waters surrounding the platform because its hard substrate supported an abundance of speckled trout. When Hotel Sid was removed last year, the trout lost a habitat they had come to rely on. 

One angler, in particular, noticed the void left by removing the platform and set out to replace the lost habitat with an artificial reef. Todd Graves, who founded Raising Cane’s near Louisiana State University in 1996, grew up fishing around the Hotel Sid platform and saw the drop in fish population last year. That prompted him to contribute to the $500,000 artificial reef, dubbed the Raising Cane’s Hotel Sid reef.

Raising Cane’s Hotel Sid is the 52nd artificial reef built along Louisiana’s disappearing coast through CCA Louisiana, the state chapter of the Coastal Conservation Association, a nonprofit founded in the 1980s to promote responsible management of the state’s fisheries resources. 

Hotel Sid was installed with funding from Graves, CCA and the Artificial Reef Trust Fund at the Louisiana Department of Wildlife and Fisheries (LDWF). At the new reef’s installation, Graves announced a further donation, for a total of $500,000, to the Coastal Conservation Association (CCA) Louisiana, to create four additional artificial reefs around Grand Isle.

Cajun Coral – a new resource for artificial reef construction

Cajun Coral has been used for coastal restoration projects in Louisiana since 2021. The 3D-printed concrete coral modules are produced by Danos in Amelia, Louisiana, a small town on the Intracoastal Canal that’s long been a fabrication hub for the Gulf.

Danos creates the concrete pieces in custom shapes for each project, with the help of Natrx geospatial software that analyzes a site’s unique wind, wave and habitat dynamics.

Once in production, the blocks are printed using a patented dry-forming technique. Then they are cured in a box mold before being transported to CCA Louisiana’s next artificial reef or shoreline stabilization project. 

In Grand Isle, when Hotel Sid’s oil platform was removed, a shell pad remained on the bottom. CCA incorporated the shell pad into the design of the new artificial reef. Cajun Coral modules were placed on top of and around the pad. 

“The bottom is not flat,” said Rad Trascher, executive vice president of CCA Louisiana. “So we took the deepest parts of [the pad] and we’re making four different reef sites around that shelter.” At the Hotel Sid site, he expects the Cajun Coral modules will create an artificial reef that grows beyond the pad to build 10,000 square feet of living reef.

 “I think this thing will be a fully living coral reef in less than a year,” Trascher said. His confidence comes from nearby Independence Island, one of CCA Louisiana’s most productive artificial reef sites, north of Grand Terre in Barataria Bay.

In 2015, CCA Louisiana and the Louisiana Department of Wildlife and Fisheries added 6,700 tons of limestone to expand the artificial reef site, Independence Island, which had first been restored in 2011. 

The Independence Island reef is not built on a decommissioned oil platform. For decades, Independence Island was a shoal, a submerged island just south of Hotel Sid – yet another example of a former marsh island that slipped beneath the waves due to coastal land loss. 

Today, Independence Island is one of the most productive artificial reefs built by CCA Louisiana, Trascher said. The crushed limestone created two parallel mounds that provide refuge for fish in this area with strong tidal flow. It is now an important habitat for aquatic organisms that attract popular recreational species such as redfish, speckled trout, black drum, sheepshead and flounder. 

But limestone has its limitations. Cajun Coral’s 3D-printing technology offers a way to build artificial reefs to more precise specifications. Because the concrete forms are customizable, modules can be built at a specific height, determined by scientists to provide the most habitat without impeding navigation.

“When we started this program 20 years ago, we had to use size 57 limestone,” said Trascher, referring to the crushed pieces of limestone often used in landscaping projects. “It was an imperfect science, raking it off the barge.” With the addition of Cajun Coral, the artificial reef-building process has become much more exact.

Rigs-to-Reefs and new opportunities for nearshore oil and gas platforms

While Cajun Coral has changed how Louisiana is able to build artificial reefs close to shore, Hotel Sid is unique, said Mike McDonough, artificial reef coordinator at the Louisiana Department of Wildlife and Fisheries.

Until now, he said, Louisiana’s Artificial Reef Program did not replace inshore oil and gas platforms, located within bays and harbors. Instead, over the past 40 years, it did a brisk business of creating reefs on offshore platforms in the open sea. 

While the program has built 33 inshore artificial reefs dispersed among the state’s coastal basins, including several in Lake Pontchartrain and at Independence Island, the projects were driven by coastal land loss and did not focus on decommissioned platforms.

The majority of oil and gas platforms slated for removal are nearshore platforms, in state and federal waters between the coastline of Louisiana and the 100-foot depth contour. 

To date, the program has built 18 artificial reefs in this nearshore zone, including several in the waters off Grand Isle. So it seems possible that many of the platforms could be prime artificial-reef sites.

Yet for nearshore oil and gas platforms, the economic incentive to turn a rig into a reef isn’t very compelling. Closer to shore, it can be less expensive for oil and gas companies to remove the platform than to turn it into a reef. 

To make the option more compelling to oil and gas companies, the Louisiana Artificial Reef Program is working to establish partnerships to support the creation of more reefs. 

The advent of customizable Cajun Coral offers Louisiana more possibilities to safely create reefs from nearshore decommissioned platforms. Though platforms help keep newly built reefs in place, past reefs were built of crushed limestone and recycled concrete structures. Using those elements, it was difficult to create reefs at heights that matched the seafloor and water currents of each area, without creating navigational hazards.

 “Trying to reef large items in shallow water is even more difficult than it sounds,” McDonough said.

Louisiana’s deeper-water reefs made from oil rigs have attracted fish for 40 years

Oil rigs attract an abundance of fish. The towering underwater platforms offer plenty of real estate for invertebrates such as sponges, corals, barnacles, mussels and sea anemones to attach onto. This creates habitat for small fish, which seek refuge and food amongst the reef. Larger fish accumulate around the rig, in search of a meal. One study, published by The National Academy of Sciences, found that oil rigs off California are among the most productive marine fish habitats globally.

It’s been nearly 40 years since Louisiana adopted its Artificial Reef Plan. From its start, in 1987, it sited its reefs on offshore oil and gas platforms. The first artificial reefs created through the program were in deeper, offshore federal waters, between the 100-foot depth contour and the U.S. Exclusive Economic Zone boundary 200 nautical miles from shore. 

Some marine-life experts even connect the high number of decommissioned oil platforms that dot the Gulf of Mexico near Louisiana to the density of fish and seafood in those waters. “Louisiana is the tuna capital of the world. We have a more plentiful snapper population than anybody,” said Trascher. “Why? Oil and gas platforms. Think of the structure we have compared to Florida or California.”

Despite these claims, some environmental advocates see the federal “Rigs-to-Reefs” program as a policy that saves money for the oil and gas industry while leaving waste in the ocean. This has prevented a similar program from developing in the North Sea, where offshore oil and gas platforms are also being decommissioned, according to research published in Ocean & Coastal Management.

The federal Rigs-to-Reefs program was designed to ease the high cost and environmental impact of completely removing offshore oil and gas platforms from the Gulf of Mexico. With the help of the federal guidelines set up by Rigs-to-Reefs, Gulf Coast states, chiefly Louisiana and Texas, because that’s where most rigs are, have built hundreds of reefs in the Gulf. So far, the Louisiana Artificial Reef Program has created 84 offshore reef sites from more than 460 decommissioned platforms.

Louisiana is also encouraging oil and gas companies to donate half of the money saved by reefing a rig to the Artificial Reef Trust Fund. Just this week, CCA partnered with Chevron, LDWF, Danos and Reefmaker-Walter Marine to construct a “super reef,” replacing a decommissioned rig at South Timbalier Block 63, about 20 miles south of Port Fourchon.

Fully removing offshore oil rigs and bringing the pieces back to shore releases large amounts of greenhouse gases such as carbon dioxide, according to research published in The Journal of Sustainable Development Law and Policy. Those warming gases would worsen rising ocean temperatures. In 2021, the United Nations found that around 90% of heat generated by greenhouse gases is absorbed by the ocean.

The success of the U.S. “Rigs-to-Reefs” program for offshore platforms drove the development of a Phase II Plan to move the reef construction closer to shore, replacing nearshore and inshore oil and gas platforms. Raising Cane’s Hotel Sid is an early example of what can be done with shallow-water decommissioned platforms. 

“These reefs will be around for generations to come and I’m looking forward to taking my grandkids out here one day,” said Graves, of Raising Cane’s. “This is a huge step in marine conservation and will enable future generations to enjoy and benefit from the great fishing that Grand Isle is known for.”