It’s not a matter of which oyster, but if any oyster could thrive in the Bay
- Comments are closed for this article.
When we take visitors onboard our survey vessel to examine oyster bar conditions in the Chesapeake Bay, they are invariably shocked by what they see. Even those aware of the crisis in the oyster fishery are not prepared for the barren moonscape-like images sent topside by our video bottom sled. The camera creeps along the bottom at a speed of one half knot, its myopic view of this once-productive bottom presenting an endless uniform landscape of sand and mud. For variety, here and there is a worm hole or scattered flecks of shell bits on the surface. This is the existing oyster habitat, representative of most of the Bay; largely a barren desert unsuited for the re-establishment of our native oyster let alone an exotic species such as the Asian oyster.
To provide some variety to this monotony, we navigate to localized portions of oyster bars where we know we will find some oyster shell, remnants of the state’s massive oyster shell replenishment effort. Every year, Maryland and Virginia have invested heavily in moving and “planting” dredged “fossil” oyster shell to improve oyster bar habitat. In Maryland, from 1960 to the present, this effort has cost between $1 million to $10 million dollars per year. When we slow the video sled over one of these recent plantings, the camera sees that even here the shell is mostly buried under a blanket of sand or mud. Live oysters are rare to non-existent.
Successful reproduction and colonization of any oyster species is dependent on oyster bars having hard substrate (predominately oyster shell) upon which oyster larvae may settle and grow. To assess how severe this lack of necessary sediment-free habitat has become, we conducted studies using novel seabed sonar classification and analysis techniques to classify and map bottom character from 38,000 acoustic samples on 18 oyster bars in the Bay—roughly 5 percent of Maryland’s total historic oyster bottom. Results showed that more than 95 percent of the state’s historic oyster bottom is presently unsuitable for oyster settlement because of an almost complete burial by mud or sand.
Further analysis, to characterize the condition of oyster plantings based on the time since they were placed on the bottom, showed that within 10–25 years of creation, all oyster shell plantings had reverted to sand or mud, with no trace of visible shell. Essentially, we validated what most watermen already knew; shell plantings serve for a few years as a potential recruitment site, which with luck, would then serve for a few years as a harvest area. Prior to the high disease years of the late 1980s, this shell planting program did serve in boosting local harvests.
To continue our analysis of the long-term effects of oyster management, we developed a model to assess the contribution of this massive financial expenditure on the current condition of Maryland oyster habitat over time and space. The model annually duplicated the area of the state’s shell plantings, the spatial overlap of plantings, and the observed rate of degradation of planted shell. Results showed no positive effect on overall oyster bar conditions for the 45 years of the program. Restored bottom was degrading faster than it could be rehabilitated. When we tested our simulation for changes in the scale of shell planting, even a fourfold increase in the size of the restoration effort produced no positive effect—just more oyster bottom reverting to sand or mud. The only factor to show a significant positive influence on the inexorable movement of shelled bottom to sedimented bottom was the effect of having living oysters growing on the bottom, mitigating or reversing the effect of sedimentation.
By these results, Maryland’s oyster management program seems to have spent considerable money and effort in an attempt to restore oysters and their habitat, leaving both, after 45 years, in much worse shape than when they started. Obviously, parasitic oyster disease and long-term harvest impacts are big factors contributing to this intertwined triage of disease/habitat loss/harvest. But, if our goal was to get a sustained return from public investments in the oyster resource, this has not happened.
As we now consider the eventuality of introducing an exotic oyster into the Bay, and possibly, willing or not, the entire Atlantic and Gulf coasts, what can we learn from Maryland’s failed efforts? Are we managing for long-term sustainability of the resource or the short-term needs of the harvest industry and consumers? How can we ensure that mistakes made in past efforts to restore the native oyster are not made again, if and when we attempt to introduce a foreign oyster? Many of the prerequisites for moving forward are independent of which oyster species is chosen for the job. Here— four issues believed to be fundamental to successful oyster restoration in the Chesapeake Bay—are offered.
Scale Dependency: Our evidence indicates that no order of magnitude increase in the present oyster restoration strategy would make even a bump in native oyster production or habitat improvement within the Bay. Our model results say that by doing it the way we are doing it now, not only can you not do it large enough, you also can’t do it long enough to accomplish anything.
In scientific investigation, things that behave in such a manner are said to be in a scale dependent domain. For example, something that works in a test tube does not work in a beaker, and something else that works in a beaker does not work in a small pond. Or, dropping a time variable into the mix, something that happens in a test tube immediately, may take a week in beaker and never happen in the pond.
Likewise, is the outcome of oyster restoration activity when it is viewed at a Baywide level. Over the 45 years of the restoration program, nearly 20 percent of the entire oyster bottom was planted in shell. Given this rate of effort, in another 200 years or so, we could claim restoration of the entire Maryland oyster bottom. But here is where scale dependency smacks us. With new restoration activity reverting to mud or sand in 20 years, we will never get there and, in fact, will be moving backward rapidly. No one wants to do the math.
Colonization as a new paradigm—Achieving the required effect of scale: No one as yet has been talking about doing things at the true scale, or required commitment, to accomplish something that will make a difference. There is a background of whining that if we just get the Asian oyster, and throw armloads into the Bay, it will all begin to happen. There is no consideration in this approach that the oyster bottom condition may be inadequate for the survival and propagation of any oyster species. Perhaps a new workable conceptual framework is in order. This must be based in cold realism, grounded in the concept of scale. We must move beyond limp soothing, eco-marketing-based approaches and slogans such as “restoration” and “recovery.” We need to get real, and get beyond things that are really just public relations, fund-raising, and photo opportunities. Let’s start fresh with the concept of colonization as a new paradigm.
Colonization is for real. It is a win or lose scenario that will play out and be measured for success in a designated time frame and spatial context. Colonization means starting from scratch and building a self-sustaining system. It could be thought of as sort of an inverse amphibious beachhead analogy. Like the martial analogy, its success involves critical time factors, immense support and coordination, and pinpoint geographic precision. Also similar to the analogy, we must be prepared to commit wave after wave of effort to obtain the footholds necessary.
Colonizing the Bay with either species will require that we put in place a single and adequately funded command structure with relentless monitoring and evaluation of restoration results. It will require a real, long-term marshaling of energies, logistics and commitments. We will need a game plan to deal with setbacks, a willingness to go back and do it again—and again—when setbacks occur.
Lessons of the past show that some things that come out of committees, consensus and compromise are often so watered down that they are unworkable. Take for instance:
- We must disallow the current scatterbrained approach of sowing as many minute postage stamp restoration sites throughout the Bay as possible. This grain to the wind philosophy has most merit in public relations. In early stages of colonization, we must focus all efforts within a few historically productive tributaries.
- Harvest and colonization do not go hand in hand until success is reached. Past experience shows us that the dual goal of producing oysters for ecological benefits as well as harvest may be a path to failure. Future scenarios must cleanly diverge into population restoration in key tributaries and site-specific aquaculture for the industry.
- The efforts needed will not happen on their own. The people out there with the real talents and skills required to accomplish these groundbreaking technical and logistical feats are not in place in our current institutions. They must not only be found, but also enticed to commit. New structures and institutions on par with this expertise and creative talent must be designed and put in place.
- Whatever oyster is the species of choice, we will be severely broodstock limited over the barren habitat we are trying to colonize. We will need to expand our capacity to produce oysters in hatcheries by orders of magnitude. If the Asian oyster is employed, we must accelerate our efforts to produce a genetically robust and well- understood animal. If we wish to move forward with the native oyster, genetics is a big player. We must have the highest disease resistance we can produce in this broodstock.
Realistically, the hardest part of this paradigm is really deciding if we want to accept the challenges in totality. Will we really ante up to the stakes, or, do we really just like the idea of all this? We either accept the challenge of successful colonization in its totality, or just continue tottering backward with feel-good projects out of step with the reality of the scale of the task.
Develop and Employ in situ Habitat Rehabilitation: If we accept that just dumping more shell will never accomplish the scale of what we need, there is another option. In situ means “in place.” In situ rehabilitation would restore shell that is already on the bottom (albeit buried or covered with sediment). This approach is attractive because the majority of traditional oyster-producing areas within key tributaries have nearly 50 years of state repletion shell lying buried in place. And this is only what is on the books. The practice of returning shell to the rivers has been a tradition for more than 100 years. The only problem we face is that all this shell is buried.
This approach does not discount the ongoing value of the fossil shell resource. For any colonization effort, the availability of stockpiles of this type shell will be extremely important to site specific restoration where in situ material may be lacking. This resource is exhaustible, though. The current dredge location is running low. Additionally, proposals to expand searches for similar buried stockpiles in the Bay face environmental challenges.
Our prototype efforts in the Bay to assess the feasibility of bringing buried shell to the surface, and or, to clean it in place, were successful. A problem lies in that oyster habitat and buried shell configuration and density are so variable that many variations of vacuuming and tilling techniques may need to be employed. This is not completely new territory. Custom-built vessels have, and are, being used in New England to clean private oyster leases.
Another important factor is that technical advances in satellite positioning technology, sonar and computer mapping now give us the capability to monitor the effectiveness of such in situ operations with the necessary precision. We can view the barren oyster bars as a farmer would examine his own fields. Thus, we will see that every little creek or river bottom has unique characteristics, something that is different when it comes to re-establishing the habitat necessary for successful colonization.
A drawback to in situ restoration is the potential adverse effects of sedimentation from these activities. This concern is not just for Bay organisms, but the oyster beds themselves. Suspending sediment in the water column for a period of time does not mean it will not resettle on oyster beds. The numbers are in our favor; but there are more deep mud areas unsuited for oysters than oyster bar. When moving sediment off bars, there will always be a net win. Pessimists may say that a permit process to approve such activity will stand in the way. Perhaps this is something we should have already been working on.
Re-Evaluate Population and Habitat Monitoring: The same oyster bar sampling tools now used for oyster management in Maryland have been us ed for more than 60 years. These implements of the 19th century oyster industry, such as sounding poles and oyster dredges, are inadequate except for determining the simple relative abundance of oysters. Likewise, only recently has data relevant to oyster management issues begun to be assembled in meaningful data formats capable of interrogation and analysis. In short, for years, not only were we not getting the information we needed to manage properly, we were unable to properly assemble and assess that information. Even with the best of intentions, no one could ever have their finger on all of the information sources and paths. The small parts did not add up to the big picture.
For new paradigms to become workable, these deficiencies need to be resolved now. We could hardly propose the undertaking that we have described without the incorporation of dedicated Geographical Information Systems as a keystone to this approach. Such computer mapping and analysis technology is embedded in most complex terrestrial applications where spatial data such as land use management and large scale agriculture is critical.
By employing the best talent in designing and applying such a dedicated system, we can begin to approach a complex colonization effort. We need first to ask not what information do we have, but what information do we need to know. We need the tools in place to record and document our efforts. We need to be able to view our remedial efforts on the bottom at the full range of spatial scales that we require. Experience from our past failure tells us that we must have the tools that allow us to measure our performance. If we can’t measure whether we are winning or losing, and how we measure the score, there is no sense in starting the game.
In presenting these views, the reader has been boldly asked on face value to: live by the tenets of a new resource management theoretical underpinning—scale dependency; dump old, public relations-based restoration spin based on fairy tale paradigms; believe there is gold buried under all that muck; and take our hand and believe technology is your friend.
This may be a hard course to swallow. Yet viewed against the context of the official status quo we have been mired in, it can be said that at least it presents a workable option. Three years ago, when we were finalizing data collection for our oyster habitat model, our federal and state governments, in trail with the usual partner signatories, were still proclaiming that we had a workable goal in effect to increase native Bay oyster populations by tenfold in 10 years. We are now at year seven of this grand plan, and by an uneducated guess may have moved in the negative direction of this goal by at least fivefold. And all of this without even a coordinated theory or paradigm of how it was to happen.This comentary drew on information from an upcoming article, “Assessment of habitat conditions of eastern oyster bars Crassostria virginica in mesohaline Chesapeake Bay,” in the North American Journal of Fisheries Management. Smith was the lead author.
Comments are now closed for this article. Comments are accepted for 60 days after publication.