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Counting Fish: Gulf of Mexico Artificial Reef Survey


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More than three thousand offshore oil and gas platforms currently stand in the Gulf of Mexico. Federal regulations have long required companies to remove everything from the sea once a well ceases production, and over the past several decades, hundreds of structures have been toppled into deep water or towed to shore to become scrap metal.

In 2010, spurred by damage to offshore structures from Hurricanes Katrina and Rita in 2005 and the Deepwater Horizon disaster earlier that year, the Department of the Interior issued a Notice to Lessees. These, according to a government official, are “formal documents that provide clarification, description, or interpretation of regulations and standards.” This one reminded oil and gas companies of their responsibility to remove idle structures, and required that some 650 of them be gone within one to five years, depending on their location and status.

Many companies took the notice to heart; in 2010, 216 platforms were removed, and in 2011, 265. Industry sources say perhaps several hundred could come out this year.

No one disagrees that improperly maintained offshore platforms pose a risk of leaks or spills. It’s also clearly more difficult and expensive to remove a mangled structure from the sea bottom than to take out a standing one.

But not everyone agrees that idle platforms should be removed at all. Almost as soon as they’re put in the water, these structures essentially become artificial reefs, providing two to three acres of habitat for sessile life such as corals, fans and sponges, along with all the usual inhabitants of a reef, from tiny blennies and gobies on up to giant grouper, sharks, rays, marine mammals, and everything in between. Their tendency to attract large schools of fish makes them popular with fishermen and divers.

State programs established in Texas and Louisiana under a federal initiative allow companies to convert platforms to official artificial reefs rather than remove them. Texas has 66 artificial reef sites, 51 of them including pieces of former platforms. Louisiana has 69 offshore reef sites.

Yet only 2 percent of decommissioned platforms in less than 100 feet of water have been reefed in the Gulf, and only 38 percent of those in waters 101 to 200 feet deep. A difficult and lengthy permitting process may be partly to blame. Nor is reefing a perfect solution; current rules require that structures be at least 85 feet below the surface of the sea – too deep for most reef life to survive.

Despite their abundance and the fact that platforms have been in the Gulf for decades, we don’t know much about the role these structures play in the greater ecosystem, while in place or once reefed. But a two-year study launched this summer by the Harte Research Institute for Gulf of Mexico Studies at Texas A&M University Corpus Christi aims to help find out.

“The whole controversy over artificial reefs and accelerated platform removal brought home for me just how valuable these structures are, from a biological standpoint as habitat, and economically for fishing,” says HRI director Larry McKinney. “There have been some studies done, but not truly definitive ones that would allow us to evaluate the value of those thousands of platforms.”

HRI scientists plan to document fish and other marine life around 15 artificial reef sites off the Texas coast (see map). The sites vary in depth, distance from shore, complexity of materials, and number of structures. This first year, each site will be evaluated for fish species and abundance, and differences between sites due to their location and materials used. Next year, representative sites will be evaluated more closely, looking at things such as vertical and seasonal patterns of fish, and how those physical differences between representative sites affect species abundance and richness.

The scientists will employ both divers and ROVs to conduct surveys. To date, the team has completed ROV surveys on four artificial reef sites and on six nearby standing platforms (which have not been reefed). Diving surveys have been completed at one standing structure. Field work will continue through the fall as weather permits. In the next few weeks, I’ll participate in a few of the trips, both diver and ROV-based, and write about them here. I’ve been scuba diving around standing platforms before, and can attest that they make for some of the best diving available, not to mention some of the most accessible.

“There is a good case to be made that artificial reefs are in fact new habitat and self-sustaining,” McKinney says. “Our goal is to say definitively yes or no, and that’s clearly what the Texas Parks and Wildlife Department, which is funding the study, wants to answer.”

He points out that apart from their potential importance as spawning habitat and for biodiversity, platforms are key to the multi-billion dollar recreational fishing industry. “Fishermen have boats that can go anywhere, and electronic gear that can find anything,” he says. “You have all this pressure to fish, and it’s economically important, so there is going to be fishing. Would we rather these people be fishing around artificial reefs, or around the natural ones? We can either help provide a place to fish and take pressure off those natural reefs, or the pressure on them will continue. We need facts so can make good decisions. “

Stay tuned.

Videos by: Harte Research Institute, Artificial Reef Monitoring Program

Melissa Gaskill About the Author: A science and environment writer based in Austin, Texas, Melissa Gaskill has a B.S. in zoology from Texas A&M University and a master’s in journalism from the University of Texas. She also has a passion for the ocean and writes about it whenever possible for publications such as Nature News, Men’s Journal, The New York Times, and many others. Follow on Twitter @MelissaGaskill.

The views expressed are those of the author and are not necessarily those of Scientific American.





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