Finding Answers Underwater

TPWD Artificial Reef Program

The Texas Parks and Wildlife (TPWD) Artificial Reef program was established in 1990 with a guiding mission to develop, maintain, promote and enhance the artificial reef potential in Texas Coastal waters. Funded through industry partners and grants, the program has established almost 100 reef sites that run along the Texas coast and include locations in both state and federal waters. These reefs include sunken ships, prefabricated concrete pyramids, culverts and a myriad of other suitable materials. All this sounds great, right? But how do we measure the success of an artificial reef?

The answer comes in the form of our biological monitoring program. Guided by a handful of burning biological questions, scientists must find a time and cost-efficient way to collect informative data. Each reef can vary greatly in the materials used, creating a problem for biologists attempting to gather consistent data. For instance, a field of concrete pyramids sitting in 70 feet of murky water will require different observation techniques than a deep-water oil and gas platform 90 miles offshore.

Different data snapshots can be combined to provide a picture of reef health. Vertical longline (VLL) fishing, water quality sampling, and scientific SCUBA diving make up the bulk of our biological monitoring techniques. Sampling physical water quality parameters such as temperature, pH, and dissolved oxygen can help us understand how environmental factors impact the biological community. Vertical longline sampling provides valuable data and physical measurements used to assess the Red Snapper population. These methods are tried and tested, and when combined, they can give us great insight. However, there is only so much we can observe topside.

Getting a fish-eye-view with scientific diving provides unique opportunities to monitor and record data below the waves. Divers can more easily observe the condition of the reef material and the diversity and quantity of its inhabitants. Scientists can get a firsthand look at how fish communities interact with the reef, and we can take note of any invasive fish species or unusual behaviors. Plus, it is very satisfying to see months, even years of paperwork and permit applications come to fruition as a teeming artificial reef! Nevertheless, working underwater can be inherently dangerous and it’s my job as diving safety officer to mitigate those risks.

TPWD Artificial reef program SCUBA dives under standards and procedures established and reviewed annually by the American Academy of Underwater Sciences (AAUS). All employees must complete an extensive 100-hour training course which includes topics on specialized diving equipment, survey techniques, and emergency management. This may seem excessive, and while research and data collection are the goal, safety is paramount regardless of the diving method used.

We use two diving methods - Roving diver surveys are performed by swimming randomly for ten minutes on the reef material, identifying fish by species and grouping into abundance categories. If a diver observes a large school of Vermillion Snapper, they would record Vermilion Snapper and mark them as abundant (more than 100 individuals). Video surveys are similar in survey time and reef position but deploy a GoPro camera mounted on parallel lasers. Focusing on recreational and commercially important species, divers will position the laser dots centrally along the lengths of individual fish. Back in the lab, clear screen grabs are taken from the video and used in conjunction with the known distance between the lasers to calculate size estimates of these fish.

Both SCUBA survey methods can give us a great snapshot of the existing biological community on a reef and when carried out over long periods of time, can even show trends. One example is the Kraken, a 371-foot long ship which was reefed in the winter of 2018. All pre-reefing dive surveys performed at the Kraken reef site saw only a few species of shark and one very friendly cobia. Post reefing, TPWD divers have observed large schools of Red and Vermillion snapper, Atlantic Spadefish, mackerel, several species of jack and grouper. Sometimes the baitfish are so thick it can interfere with the laser survey!

However, benefits always come with drawbacks. Reef sites which sit in murky water or at extreme depths are probably not the best candidates for SCUBA. Vertical long lines and water quality sampling are just a couple of research methods used in addition to diving, so we can paint a more complete biological picture.

Ultimately, the monitoring we do lays the foundation for our program. Working with the knowledge we gain, TPWD can make valuable management decisions in building and placing new reefs. These artificial reefs go on to create enhanced fishing and diving opportunities for coastal communities, bringing both economic and biological success to the coast of Texas.

For more information about the Texas Artificial Reef Program, contact us at (281) 534-0147 or via email at [email protected]. Join us on Facebook at www.facebook.com/TexasParksAndWildlifeArtificialReefProgram.