Oyster Reef Restoration in Texas: A Balancing Act

Emma Clarkson | Habitat Assessment Team Lead, TPWD Coastal Fisheries Division
Oyster Reef Restoration in Texas: A Balancing Act
Figure 1. Over the past decade, Texas Parks and Wildlife Department has restored over 500 acres of oyster reef (shown in red) in Texas bays. The majority of these restoration projects are in Galveston Bay, which has over 15,000 acres of natural oyster reef (shown in black).

If you’ve lived in Texas for any amount of time you’ve likely had the opportunity to eat an oyster. You may like to eat these briny treats raw, fried, or covered in butter, or you may absolutely hate the taste and texture. But even people who don’t enjoy eating oysters can still enjoy the benefits that oysters provide. These benefits largely stem from the oyster’s unique growth habit - like tropical corals, oysters grow cemented together in clusters to create a structure that we call reefs. This structural complexity supports a diverse underwater community where the reefs provide a refuge for small fish, crabs, and shrimp, and a buffet for their hungry predators. The benefits from this rich community trickle up to anglers’ coolers, and these reefs are often targeted by anglers for their known abundance of fish. These structures do more than just benefit sea life and anglers – they also reduce wave energy and stabilize sediments, which reduces shoreline erosion, while the oysters themselves improve water quality and clarity by filtration. The additional benefits provided by oysters and the reefs they form are known as “ecosystem services”, and the services oysters provide go far beyond the production of plump tasty snacks by increasing the health and resiliency of ecosystems.

Unfortunately, many of the oyster reefs in Texas have been degraded by both natural events and human activities; some reefs have been buried by storms, some oyster communities have died from changes in water quality or currents, some have been impacted by coastal development, and some have experienced heavy harvest pressure that has reduced the structural complexity of the reefs. When reefs become degraded, not only do commercial and recreational fishing communities suffer, but ecosystem services can also be lost.

The story of oysters and their reefs does not have to end with degradation and loss. Fortunately, oyster reefs can be restored. By placing cultch (hard materials such as limestone, shell, or river rock) into a bay, spat (baby oysters) can settle, grow, and form reefs. Over the past 12 years, Texas Parks and Wildlife has successfully restored over 500 acres of oyster habitat (see Figure 1) and plans to continue restoration efforts. While TPWD is proud of this success, 500 acres is just a drop in the bucket when compared to the oyster reef habitat in Galveston Bay (over 15,000 acres) and Copano Bay (over 6,300 acres).

So how does TPWD decide what area or site to focus restoration efforts when there are so many places to choose from? Appropriate site selection is one of the most critical parts of the restoration process because it can make or break a project. Site selection starts by identifying areas where restoration is likely to be successful. Poor site selection can result in the cultch sinking into the mud or oysters dying. In general, we focus on areas with suitable water quality conditions that have oyster habitat that is physically degraded from impacts such as storms or fishing pressure. Rather than going into details of the hydrological and biological thresholds for the species, suffice it to say, we have a pretty good idea of where oysters will have the best chance at growing and surviving and where they will not. We always place our cultch where oyster growth and survival are likely.

The bigger question is, what are we trying to accomplish by restoring oyster habitat? By no surprise, a common goal for a restoration project is to maximize the number of market-sized oysters on a reef, but restoration projects can also have the goal of improving ecosystem services, like the enhancement of fish habitat or increased shoreline protection. Let’s use Galveston Bay as an example. The salinity in East Galveston Bay is ideal for oyster growth and survival. Therefore, restoration efforts in East Bay may focus on increasing the number of market-sized oysters, which would subsequently benefit surrounding oyster reefs as well as the oyster industry. West Galveston Bay, in comparison, has higher salinity that may promote the occurrence of oyster predators or disease. However, oysters will spawn, settle, and grow in the salty waters of West Galveston Bay, even in the presence of such challenges, creating a complex habitat that fully supports fish communities, enhances angling, and improves water quality. Restoration projects in West Galveston Bay may focus on enhancing these ecosystem services, and just because it may result in fewer market-sized oysters, that does not mean restoration in West Galveston Bay is less valuable or less likely to be successful.

There is, unfortunately, often a trade-off between oyster harvest intensity on the reef and the magnitude of ecosystem services provided by the reef, which must be considered when selecting a restoration site. Our goal is to choose restoration sites that maximize the quantity and quality of ecosystem services so that everyone, including recreational anglers, commercial fishers, and fish and wildlife resources, can reap the rewards. The key to a successful restoration program is to balance the ecosystem needs with those of the people who enjoy it and depend on it for their livelihood, and that includes choosing restoration sites that address all of these needs. A single project site alone cannot benefit everyone equally, and so addressing multiple needs is often accomplished by implementing multiple projects with different goals. The true “success criteria” of the TPWD restoration program is maintaining both healthy wild oyster populations and the reef habitat and community they support, because you cannot have one without the other.