10
Decision Making and Recommendations for Future Research

TO INTRODUCE OR NOT TO INTRODUCE?

In deciding whether to approve or disapprove the introduction of a nonnative oyster, either open-water aquaculture of sterile triploid oysters or deliberate establishment of a reproductive population, policymakers must weigh the potential risks and benefits associated with introducing a nonnative species. For the Chesapeake Bay region, policymakers have been unable to reach agreement on whether nonnative oysters should be part of the response to the collapse of the native oyster population. Recent experiences with attempts to eradicate or even control invasions by nonnative nuisance species have left many resource managers averse to approving introductions of exotic species. On the other hand, there is growing impatience with the apparent failure of current efforts to rebuild stocks of the native oyster to support the oyster fishery. This study was commissioned to define and assess the risks and benefits of introducing the Suminoe oyster to help reconcile these two points of view.

In general, deliberate introductions of exotic species have had mixed success. Although many new species have been imported without major consequences, the exceptions include nuisance species that have precipitated dramatic and typically irreversible changes to ecosystems. To assess the potential threats associated specifically with oysters, the committee reviewed the results of previous oyster introductions (Chapter 3). The oysters themselves are a problem in some cases but not others. Introductions of the Pacific oyster, Crassostrea gigas, into several areas in Australia and New Zealand, for example, resulted in unanticipated losses of native oyster



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 232
Nonnative Oysters in the Chesapeake Bay 10 Decision Making and Recommendations for Future Research TO INTRODUCE OR NOT TO INTRODUCE? In deciding whether to approve or disapprove the introduction of a nonnative oyster, either open-water aquaculture of sterile triploid oysters or deliberate establishment of a reproductive population, policymakers must weigh the potential risks and benefits associated with introducing a nonnative species. For the Chesapeake Bay region, policymakers have been unable to reach agreement on whether nonnative oysters should be part of the response to the collapse of the native oyster population. Recent experiences with attempts to eradicate or even control invasions by nonnative nuisance species have left many resource managers averse to approving introductions of exotic species. On the other hand, there is growing impatience with the apparent failure of current efforts to rebuild stocks of the native oyster to support the oyster fishery. This study was commissioned to define and assess the risks and benefits of introducing the Suminoe oyster to help reconcile these two points of view. In general, deliberate introductions of exotic species have had mixed success. Although many new species have been imported without major consequences, the exceptions include nuisance species that have precipitated dramatic and typically irreversible changes to ecosystems. To assess the potential threats associated specifically with oysters, the committee reviewed the results of previous oyster introductions (Chapter 3). The oysters themselves are a problem in some cases but not others. Introductions of the Pacific oyster, Crassostrea gigas, into several areas in Australia and New Zealand, for example, resulted in unanticipated losses of native oyster

OCR for page 232
Nonnative Oysters in the Chesapeake Bay populations that had been commercially harvested. Introductions of this same oyster to the U.S. West Coast and France filled voids created by previous overharvesting or diseases of native species and have become the basis of extensive aquaculture industries. It is impossible, given the present state of knowledge, to predict whether the Suminoe oyster will be a boon or an ecological disaster in this sense. The committee’s review of case studies clearly indicates that greater ecological or economic harm typically arises from organisms that are inadvertently introduced with the foreign oyster. With the exception of pathogens (including some viruses) that can be transmitted from adults to their progeny, unwelcome “hitchhiking” organisms can be avoided by strict adherence to the International Council for the Exploration of the Sea (ICES) protocols, which specify that only hatchery-reared nonnative oysters should be allowed in open waters. Current proposals to use the Suminoe oysters stipulate adherence to ICES protocols to minimize the risk of introducing a disease organism or other unwanted species. Although the nonnative oysters could become an unwelcome invasive species, this risk is probably lower than the risk of introducing a multitude of alien species incidental to an illegal rogue introduction. Consequently, regulatory and enforcement measures should be taken to reduce the risk of a rogue introduction. Development of a quantitative risk assessment model for evaluating risks associated with the three management options would require a great deal of additional research that could take many years to complete. Moreover, while risk assessment is a tool for characterizing the likelihood of various outcomes, it does not provide a basis for determining whether an outcome or combination of outcomes is desirable or undesirable. That is, risk assessment may inform the decision-making process but cannot replace it. Nevertheless, a decision must be reached about whether or not to proceed with the use of the nonnative oyster despite uncertainty about the type and magnitude of the potential risks involved. Regulators and decision makers will need to consider all available information and weigh the often opposing interests of the various stakeholders to decide whether to allow introduction of the nonnative Suminoe oyster, C. ariakensis, into the Chesapeake Bay, either limited to aquaculture of the sterile triploid or as a deliberate inoculation of reproductive diploids. This is a particularly difficult circumstance because of the magnitude of uncertainty associated with each option and the perception, on all sides, that any decision will have lasting and serious consequences. Various decision analysis techniques have been used to clarify objectives and elucidate the effects of uncertainty on the possible outcomes of alternative management actions for similarly difficult decisions (e.g., Keeney and Raiffa, 1976; Hilborn and Walters, 1977; Walker et al., 1983; Bain, 1987; Saaty, 1990; Merritt and Criddle, 1993). The intention here is not to conduct a comprehensive deci-

OCR for page 232
Nonnative Oysters in the Chesapeake Bay sion analysis but to sketch a road map for assessing the likelihood of achieving the various goals under each of the three management options. In decision analysis the likely impact of an action is assessed relative to the uncertainty of the outcome, the reversibility of the action, and the likelihood of unintended consequences. The first step in decision analysis requires clear definition of the management objectives and stakeholder concerns. At the study’s October 2002 workshop, the committee heard presentations by various stakeholders involved in the question about how best to restore oysters (native or nonnative) to the Chesapeake Bay. Two major goals were expressed by this diverse assemblage of interested parties: (1) build a profitable oyster production and processing sector that is competitive in local, regional, and global markets and (2) improve ecological conditions in the Chesapeake Bay through restoration of oyster beds. These overarching goals share some common features but differ in other respects. For example, it may be possible to develop a profitable fishery without restoring oyster populations in the bay. Similarly, restoring oyster populations will not necessarily lead to the restoration of a profitable fishery or to meaningful changes in water quality. Different stakeholders support the major goals for different reasons. By decomposing the major goals into their constituent parts, the effects of a management action can be analyzed for more precisely defined subobjectives, thereby making the consequences of decisions more obvious and understandable. Moreover, elucidation of subobjectives often reveals common interests that can form the basis for decisions supported by multiple stakeholders. Each management option should be assessed for its efficacy in addressing these subobjectives in addition to the major goals. Again, the uncertainty of outcomes, reversibility of actions, and potential unintended consequences should be elucidated. The committee was asked to assess whether or not there was sufficient information to support risk assessments of three management options. The committee concluded that quantitative risk assessments could not be conducted based on existing data but found that differences in the types of risks associated with each option could be described. On the basis of existing information about oysters in general and the Suminoe oyster in particular, Option 3—direct introduction of reproductive Suminoe oysters—would likely have a moderate to high chance of increasing the abundance of oysters in the Chesapeake Bay, particularly if it was done as a massive introduction, much as the Pacific oyster was introduced into France. To the extent that the introduction was successful, this action might reduce the likelihood of a rogue introduction. However, because of the lack of information on the biology and ecology of the Suminoe oyster, there is a high degree of uncertainty about the outcome of an introduction. The changed environment in many parts of the bay

OCR for page 232
Nonnative Oysters in the Chesapeake Bay may no longer support the survival and growth of any oyster. Baywide, the Suminoe oyster may not perform as it has in the limited field tests conducted to date. It may prove susceptible to native pathogens, parasites, or predators. It may not form reefs but may instead spread as a thin layer on soft bottoms, smothering native fauna. It may become established and abundant but have low commercial value if, for example, there is a high incidence of mud blisters or if it has a short shelf life. The nonnative oyster may spread outside of the bay, where it could have negative impacts on still-healthy populations of the native Eastern oyster. Finally, it is unlikely that the Suminoe oyster could be eradicated after it was introduced; thus, any undesirable consequences that ensue would be permanent. In sum, the irreversibility of introducing a reproductive nonnative oyster and the high level of uncertainty with regard to potential ecological hazards make Option 3 an imprudent course of action. Option 1—no use of nonnative oysters—is unlikely to result in significant changes in oyster abundance in the bay in the near term. This outcome has moderate uncertainty, owing to external events or actions that might favor the recovery of native oyster populations (e.g., favorable climate change or success in restoration efforts employing selectively bred, disease-resistant stocks). Although Option 1 is reversible in the sense that nonnative oysters could still be introduced at some time in the future, this option includes the risk of continued losses to the oyster industry and erosion of confidence in government action. One possible response to the latter is increased risk of a rogue introduction and the especially high hazards associated with unintentional cointroductions of disease organisms or nuisance species. Option 2—sterile triploid aquaculture carried out with strict accountability and best management practices to minimize the risk of diploid escape—would probably have little impact on total oyster abundance because even expanded aquaculture operations are unlikely to produce a volume of oysters at the scale of the natural populations in the Bay. Uncertainty associated with this action would be low. The reversibility of this option depends on the effectiveness of measures taken to prevent reproduction; if aquaculture is practiced at a small scale, the probability of reproduction will be low and the reversibility of this management action will be high. The probability of introduction of reproductive oysters would increase if triploid aquaculture were to expand dramatically. Over the long term it is likely that some nonnative oyster larvae will be spawned; whether the larvae will survive, establish a nonnative population, and spread throughout the bay is unknown. The potential number of larvae released is directly related to the scale of triploid aquaculture. Under Option 2, dramatic expansion of aquaculture effectively grades into a small-scale diploid introduction as described for Option 3. The perception that Option 2 represents management action rather than inac-

OCR for page 232
Nonnative Oysters in the Chesapeake Bay tion (Option 1) might reduce the likelihood of a rogue introduction. Over 6 or 7 years, controlled and strictly regulated triploid aquaculture could provide critical biological and ecological information now lacking for the Suminoe oyster. It would also allow time to assess whether climate variation or new approaches to restoration are effective at reversing the decline of the native oyster. Option 2 has already received considerable scrutiny by the Chesapeake Bay Program and its member states and federal agencies. Limited field trials with triploid nonnative oysters have already been conducted in Virginia and outside the bay in North Carolina’s coastal waters, and larger trials are in the advanced planning stages in both states. To a limited extent, the decision to introduce triploid Suminoe oysters has already been made. The risks of proceeding with triploid aquaculture in a responsible manner, using best management practices, are low relative to some of the risks posed under the other management options. If regulators enforce strict protocols for accountability and require collection of the biological, economic, and social information necessary to evaluate the risks and benefits of culturing or introducing the nonnative oyster, this management option could provide useful information to support decision analyses and risk assessments regarding the future use of nonnative oysters in the Chesapeake Bay. UNREALISTIC EXPECTATIONS AND COMMON MISCONCEPTIONS In evaluating the scientific evidence bearing on the potential risks and benefits of introducing a nonnative oyster into the Chesapeake Bay, the committee finds relatively little scientific support for many of the common assumptions that have shaped public discourse on this issue. These assumptions should be treated with healthy scientific skepticism if progress is to be made in resolving the problem. As a prelude to recommendations for action and future research, we portray five such misconceptions as “myths.” These five myths may not be the only misconceptions and assumptions surrounding this complicated issue, but they do reveal major gaps in knowledge and uncertainties confronting a decision about whether or not to introduce a nonnative oyster into the Chesapeake Bay. Myth I: Declines in the Oyster Fishery and Water Quality of the Chesapeake Bay Can Be Quickly Reversed This is an overarching myth with respect to hopes for the success of restoration efforts and to the issue of nonnative oyster introduction, rooted

OCR for page 232
Nonnative Oysters in the Chesapeake Bay perhaps in fundamental cultural beliefs in the power of technology and control over nature (McPhee, 1989). The oyster fishery in the Chesapeake Bay has been in decline for about a century; the native oyster is on the verge of local economic extinction. Also, water quality has declined as a consequence of numerous activities over a long period of time, including urbanization, deforestation, agriculture, overfishing, shell mining, and waste disposal. The belief that these trends will be readily reversed, restoring the bay to some semblance of its pristine past, is unrealistic. The failure of a succession of corrective actions to reverse the decline in the fishery—relaying of spat on cultch, restoration of shell-reef habitat, establishment of sanctuaries, hatchery enhancement—each of which was once thought to be the solution to the bay’s problems, is testimony to the absence of easy answers and quick fixes. Progress on reversing the long-term declines in oyster populations and water quality will be achieved only when unrealistic expectations for a quick fix are replaced with a long-term commitment to systematic approaches for addressing the bay’s complex multidimensional problems. Progress may also depend on climate variation. The native oyster has been rendered particularly vulnerable to disease by a series of drought years with milder than usual winters, conditions that increase infection rates and mortality. The native oyster would benefit enormously from a reversal of this climate pattern and a return to wetter years with colder winters, which would inhibit proliferation of parasites in the oyster and provide oyster populations with more low-salinity refuges from diseases. Variation in climate patterns, on interannual and perhaps interdecadal timescales, must be incorporated into expectations about the recovery of the native oyster and the ecology of the bay. Myth II: Oyster Restoration, Whether Native or Nonnative, Will Dramatically Improve Water Quality in the Chesapeake Bay The role of filter-feeding bivalves in estuarine ecosystems has been well documented (e.g., Dame, 1993), but the conventional wisdom that either a disease-free native oyster or a nonnative oyster could repopulate the Chesapeake Bay to an extent that would restore water quality and dramatically improve the condition of the bay’s living resources is unreasonably optimistic given current environmental conditions. The connection between oysters and water quality was popularized by the oft-cited calculation suggesting that the native oyster was abundant enough, even in the late 19th century, to filter a volume of water equal to that of the Chesapeake Bay every 3.3 days, while today’s depleted population takes nearly a year to filter the equivalent volume (Newell, 1988). Although this type of calculation dramatically illustrates how oysters may have contrib-

OCR for page 232
Nonnative Oysters in the Chesapeake Bay uted to the ecology of the bay in the 19th century, it is a fault of logic to assume that all of the bay’s current water quality problems are the consequence of the loss of the oyster population and therefore can be corrected by efforts to restore this population. Other ecosystem stressors have intensified since the late 19th century, including increased nutrient runoff, higher sediment loads, climate shifts, and more toxic chemical pollution. These stressors could delay or prevent the expected improvements in water quality predicted with restoration of the oyster population. Gerritsen et al. (1994) conclude that in regions of the bay with exceptionally high numbers of suspension feeders (e.g., upper shallow reaches, oligohaline regions of the bay), most of the primary production (phytoplankton biomass) is consumed by zooplankton and bivalves. Although the oyster population has declined in these areas, several species of invasive bivalves now provide a similar functional role as the oysters. In the middle and deeper regions of the Chesapeake, less than 50% of the primary production is consumed, and physical attributes of the bay’s deeper waters will always limit the ability of suspension feeders to reduce the volume of phytoplankton biomass. These authors conclude that restoring oyster populations could improve water clarity in shallow zones, but for the large volume of water in the main stem of the bay, much more comprehensive efforts will be necessary to achieve significant improvements in water quality. Increasing the biomass of suspension-feeding bivalves (in this case oysters) has the potential to enhance biofiltration. Under controlled triploid aquaculture, however, the effects will be spatially limited to the immediate grow-out areas. Intensive triploid aquaculture, similar to some of the coastal bays and lagoons in France where the Pacific oyster is raised, could increase filtration enough to improve water clarity in some of the shallow, retention-type tributaries of the bay. If diploid nonnative oysters were introduced and populated the bay, water clarity in shallow reaches could improve, an outcome similar to the zebra mussel invasion of the Great Lakes. However, high fishing pressure and mortality from predators of the native species (e.g., fish, crabs) could limit the population size and spread of an introduced oyster. In contrast, zebra mussels have no commercial value in the Great Lakes and are often found in areas where there are no natural predators. Lastly, increased sedimentation of prime oyster settlement areas could prevent any oyster from achieving as large an abundance as the historical population of native oysters. This myth, though it has served to make political bedfellows of diverse stakeholders who share the goal of increasing the oyster population in the bay, should be replaced by the more realistic assumption that declining water quality results from multiple stressors that cannot be reversed by simply stocking more oysters in the

OCR for page 232
Nonnative Oysters in the Chesapeake Bay bay. Oysters are only one part of the solution to the complex problems that affect water quality in this region. Myth III: Restoration of Native Oyster Populations Has Been Tried and Will Not Work Disenchantment with the failure of restoration efforts is evident in press accounts and the testimony received by the committee at its public meetings. While current advocates of restoration may claim that past expectations were too high and that signs of limited success exist, it is clear that despite the considerable resources that have been expended, large-scale reversals in the decline of native oyster populations have not been achieved. Nevertheless, it would be erroneous to infer that future restoration efforts will be entirely ineffectual. Restoration efforts to date have not corrected or ameliorated the multiple stressors that contributed to the loss of native oysters. For example, restoration efforts that address reef habitat but do not address disease are not likely to succeed. Similarly, restoration efforts that serve only to create a put-and-take fishery are unlikely to yield meaningful increases in baywide oyster populations. The idea of using disease-resistant oyster stocks for restoration rather than aquaculture has only recently been explored (Allen and Hilbish, 2000). The incidence and severity of oyster diseases have been exacerbated by drought conditions for the past 4 years. A series of more typical colder and wetter winters could give restoration efforts a substantial boost relative to progress in the recent past. Myth IV: C. ariakensis Will Rapidly Populate the Bay, Increasing Oyster Landings and Improving Water Quality The assumption that the Suminoe oyster will rapidly invade the Chesapeake Bay is heralded by those who see this as the salvation of a fishery on the verge of extinction and abhorred by those who fear ecological disaster. Champions of introduction base their assumption of rapid proliferation on the results of small field experiments with triploid C. ariakensis, in which the nonnative oyster grew rapidly and was resistant to or tolerant of the two diseases affecting the native oyster (Calvo et al., 2001; Thompson, 2001). The specter of an ecological disaster, on the other hand, is made by analogy to the negative consequences of invasions by the zebra mussel and other nuisance species. However, there are no data to suggest that reproductive populations of C. ariakensis will necessarily enjoy a rapid rate of population growth in the Chesapeake Bay. The Suminoe oyster has not invaded the West Coast of the United States, where it was inadvertently introduced with C. gigas in the 1970s (Langdon

OCR for page 232
Nonnative Oysters in the Chesapeake Bay and Robinson, 1996), but this may not be a reliable indicator of its likelihood of becoming invasive on the East Coast. For example, the Pacific oyster has not been invasive on the U.S. West Coast, but in New Zealand and Australia this same species has invaded and displaced the native rock oyster. Indeed, review of the consequences of oyster introductions around the world suggests the difficulty if not the impossibility of predicting whether or not the Suminoe oyster will be invasive in the Chesapeake Bay and beyond. This myth is also based on the assumption that there has been no loss of suitable oyster habitat in the bay and that the current environment is capable of supporting oyster populations as large as those in the past. Increased sedimentation in the bay from upland sources already limits settlement of native oysters; the settlement of nonnative oysters would be similarly affected by sedimentation. Myth V: Aquaculture of Triploid C. ariakensis Will Solve the Economic Problems of a Devastated Fishery and Restore the Ecological Services Once Provided by the Native Oyster The primary motivation for pursuing triploid aquaculture of C. ariakensis is to reduce the risk of establishing a reproductive population of nonnative oysters in the bay. The use of triploids, however, does not completely eliminate the risk of nonnative oyster introduction. Indeed, the release of fertile diploids from aquaculture of triploid oysters is considered inevitable by a consensus of scientists, watermen and producers, regulators, nongovernmental organizations, and concerned citizens from Virginia, Maryland, North and South Carolina, Delaware, and New Jersey (Hallerman et al., 2001). However, this risk can be managed and reduced through application of stringent aquaculture protocols as described in the section below. A primary risk management strategy is to contain triploid oysters so as to ensure their removal from the water before they are likely to reproduce. Triploids may reproduce either through spawning of the small percentage of diploid oysters that occur in each batch of triploids, through spawning of triploid oysters that can produce diploid offspring, or through age-dependent reversion of triploid reproductive tissue to the diploid condition. Contained aquaculture, however, is likely to be limited by the relatively high costs of materials and labor. On the U.S. West Coast, single oysters are produced in contained aquaculture for the half-shell market, in which premium prices offset higher production costs. Contained aquaculture may not be competitive if the product is destined for the traditional shucked-meat market. Thus, contained aquaculture of triploid oysters would likely involve only a fraction of the bay’s oyster industry, and the scale would be too small to make a noticeable difference in the water quality of the Chesapeake Bay. Success with trip-

OCR for page 232
Nonnative Oysters in the Chesapeake Bay loid aquaculture could lead, however, to a push by industry for more economical on-bottom culture, which might be more competitive with wild harvest fisheries but would increase the risk of diploid escape, reproduction, and establishment. RECOMMENDATIONS Biosecurity Against Rogue Introductions Regulations against rogue introductions and enforcement of existing regulations should be reviewed by responsible state agencies and the Chesapeake Bay Program. The likely routes of introduction and critical points where interdiction might be achieved should be identified, along with the resources required to achieve various levels of biosecurity. Genetic profiling of natural populations of C. ariakensis has begun (Francis et al., 2001) but should be expanded to make available a suitable set of diagnostic markers for forensic applications, such as determining the provenance of any unsanctioned introductions that are discovered. Most importantly, the public should be educated about the risks of unregulated introduction of nonnative oysters to increase awareness and vigilance. Development of Standards for Regulating Nonnative Oyster Aquaculture Before the commencement of open-water aquaculture (or pilot-scale field trials), the committee recommends the development of a stringent protocol to minimize and monitor the unintentional release of sexually competent C. ariakensis. The Hazard Analysis Critical Control Point system used in the field of food safety provides a framework for the development of the type of protocol that will be required. The protocol should include: assessment of the security of confinement and certification of adult brood stock, larvae, and seed in the hatchery producing the triploids; sampling to detect the frequency of diploid oysters in triploid seed lots produced by tetraploid by diploid crosses (chemical induction should not be used to induce triploidy because of the relatively high percentage of diploid larvae produced); statistical determination of the density of culture that reduces the risk of cross-fertilization of gametes from these diploids to an acceptable level; sampling to monitor gonadal maturation and to detect reversion;

OCR for page 232
Nonnative Oysters in the Chesapeake Bay standards and protocols for removing nonnative oysters in the event of catastrophe, such as a storm, a disease outbreak, or unusual rates of gonadal maturation or reversion; accurate accounting of all animals, from hatchery through growout and disposal, including the use of genetic markers for identification in case nonnative oysters are found in open waters outside the grow-out containers; sampling protocol to detect morbidity and to ascertain the causes of unusual mortalities; documentation and prior approval of the transfer or relaying of nonnative oysters; estimation of the probability of control system failure, resulting in the escape or disappearance of subject oysters; and identification of parties responsible for monitoring and enforcement. Bonding should be considered as an incentive to enhance compliance with the control system protocols. Biological Research Large gaps in biological knowledge exist for both native and nonnative oysters, and the biology of both species needs to be understood in the broader context of long-term environmental change in the Chesapeake Bay. The committee thus recommends a spectrum of biological research to provide information for risk assessments of the three management options, from specific near-term objectives to broader longer-term research goals. Many of these recommendations have been the subjects of previous or current research, but because the problems addressed are extremely complex, answers to some of these research needs will require significant effort over a period of several years. The largest and most immediate gaps in knowledge concern the nonnative oyster. Some of this research could be conducted in quarantined experimental facilities; some of it could be conducted in conjunction with experimental field trials using triploid nonnative oysters. If introduction of triploid or diploid oysters does proceed, it should be done with riskaverse management practices based on a foundation of biological information. Data from such research should be integrated immediately into models of the biological risks associated with introduction of nonnative oysters as either triploids or diploids. Several short-term research objectives are needed to address critical gaps in knowledge of the biology of the nonnative oyster:

OCR for page 232
Nonnative Oysters in the Chesapeake Bay continue the development and refinement of assay methods and hatchery protocols for the detection and elimination of pathogens that might be introduced, even using ICES protocols, via vertical transmission in oyster gametes; determine the susceptibility of C. ariakensis to Bonamia ostreae through challenge experiments, by obtaining DNA from the Bonamia-like organism associated with a C. ariakensis mortality in France (archived material available from IFREMER, La Tremblade) for comparison with known B. ostreae sequences, or both; develop a better understanding of C. ariakensis biology in the Chesapeake Bay, particularly its growth rate, gametogenic cycle, larval behavior, and settlement patterns in different hydrodynamic regimes; size-specific postsettlement mortality rates and susceptibility to native parasites, pathogens, and predators incorporating salinity and temperature dependencies of all features; develop sufficient data on the fidelity, stability, and fertility of mated triploid C. ariakensis to permit estimates not only of mean parameters, such as the proportions of triploids, diploids, or mosaics in lots of mated triploid seed, the proportion of triploid individuals undergoing gametogenesis, the fecundity of triploids, the types and proportions of gametes produced by triploids, the fertility of these gametes, etc., but also estimates of uncertainty in these parameters; determine the distance and range of concentrations over which fertilization can be achieved under various conditions of water flow; determine the ecological interactions of C. ariakensis and C. virginica at the juvenile, adult, and gametic life stages; and determine the genetic and phenotypic diversity of different geographic populations of C. ariakensis and other closely related Asian species of the genus Crassostrea and the extent to which they might respond differently to the Chesapeake Bay environment. Longer-term research goals, though not immediately applicable to a decision about introducing the nonnative oyster within the next few months or years, are needed, nevertheless, to address larger questions about the ecological role and future abundance or success of native and nonnative oysters in the Chesapeake Bay: develop an integrated approach to understanding the responses of native and nonnative oysters to environmental change and multiple stressors, including naturally occurring or introduced dis-

OCR for page 232
Nonnative Oysters in the Chesapeake Bay eases, climate change, land use, nutrient loading, sedimentation, pollutants, and the interactions of these factors; develop an integrated, science-based approach to restoration of the native oyster. This would include development of an effective breeding program for building genetically diverse native oyster stocks that are tolerant of or resistant to Dermo and MSX. Integrate the resulting disease-tolerant or disease-resistant stocks into the restoration of protected sanctuary areas that favor local recruitment, as recommended by Allen and Hilbish (2000). Perform a cost-benefit analysis of an integrated restoration program; develop a model of oyster larval dispersion based on a detailed circulation model for the Chesapeake Bay; incorporate information about differences in the larval behavior or physiological performance between the native and nonnative oysters to predict their dispersal throughout and outside the Chesapeake Bay; determine the causes of recruitment success or failure for C. virginica; determine the success of sanctuaries for the native oyster and their relationship to recruitment; determine the genetic and physiological bases for disease tolerance or resistance of native oysters; determine why native oysters are not developing natural resistance in the Chesapeake Bay but do seem to be developing resistance in Delaware Bay; and determine the ecological role of oyster reefs, whether they are simply attractants or whether they provide essential services to species. The number and difficulty of these big questions highlight the complete uncertainty about the outcome of such a dramatic ecological experiment as introducing a diploid nonnative oyster into the Chesapeake Bay, either directly or indirectly as the consequence of escape from triploid aquaculture. Decision Making and Regulatory Framework Characterize Public Versus Private Use of Submerged Lands As discussed in Chapter 8, states differ in the extent of submerged lands offered for leasing, the security and enforcement of leaseholders’ exclusive use rights, the conditions and constraints imposed on leaseholders, and the duration and conditions for renewal of leases. These institutional differences have shaped the development of oyster fisheries

OCR for page 232
Nonnative Oysters in the Chesapeake Bay in Virginia and Maryland and will affect the economic and sociocultural impacts of the three management options. A better understanding of the institutional differences, their consequences, and their possible evolution will be critical to predicting the outcomes of the proposed options, the ability of managers to oversee and control production practices, and the potential for Maryland and Virginia oystermen to compete with producers in other regions. Institutional differences, their consequences, and their possible evolution need to be assessed. A better understanding of these factors will be critical to predicting the outcomes of the proposed options, the ability of managers to oversee and control production practices, and the potential for Maryland and Virginia oystermen to compete with producers in other regions. Evaluation of Alternative Institutional Structures The rules that govern access to fishery resources and the utilization of those resources have been shown to exert an important influence on the level of excess capital investment, the dissipation of economic profits, and the incentive to weigh the consequences of excessive harvests. Unlike other shellfish and finfish fisheries, the oyster fishery has not been carefully examined with regard to the attributes of alternative institutional designs. During this period of evolution in the oyster fishery, the current institutional structure and alternative structures should be reassessed. This analysis could consider the applicability of individual transferable quotas or harvester cooperatives, individual and community territorial use rights in fisheries (TURFs),1 limited entry, long-term leases, and other institutional designs. Review the Chesapeake Bay Program’s Decision Making Authority In Chapter 8, the existing regulatory and institutional framework was found to be inadequate for monitoring or overseeing the interjurisdictional aspects of open-water aquaculture or direct introduction of C. ariakensis. While the Chesapeake Bay Program (CBP) appears well positioned to assume monitoring and oversight authority, its decisions are nonbinding. Moreover, the CBP does not appear to have sufficient budget or personnel resources to support analyses of the ecological, economic, or sociocultural consequences of alternative management actions. 1   TURFs are spatially based individual or collective harvest privileges that have often been established in less industrialized and smaller-scale coastal fisheries where management has been based on restricting participation to a localized population in a limited geographical area (Christy, 1982; Seijo, 1993).

OCR for page 232
Nonnative Oysters in the Chesapeake Bay The committee recommends a review of the CBP, by parties to the Chesapeake Bay Agreement, to determine whether the CBP could serve as a venue for interjurisdictional decision making and to identify what institutional changes would be required for the CBP or another multistate entity to have binding authority over management decisions that could affect the bay. Economic and Sociocultural Analyses Development of Baseline Data The current economic and sociocultural characteristics of the oyster fishery and fishery-dependent communities need to be carefully documented to serve as a baseline for postimplementation analyses of the impacts of whatever actions are taken. Recent trends in the economic and sociocultural data series and likely ongoing trends also need to be documented to help isolate postimplementation changes that are a direct result of management action as opposed to the continuation of prior trends. Economic Feasibility of Alternative Production Systems Restoring oyster production to 1985 production levels using the same old production technologies operating under the same old institutional arrangements is unlikely to yield profits comparable to those realized in 1985; much of the rest of the world has moved past the hunter-gatherer stage of oyster production. The economic viability of different production systems should be examined for each management option and by production region. For example, under the status quo, estimates should be developed for the profitability of public and leased-bottom fisheries in Virginia and Maryland for tong, dredge, diver harvest, and power-dredge production modes. These traditional modes should be compared with the profitability of relaying to manage disease exposure, seeding of selected stock, and so forth. Similarly, examination of triploid nonnative aquaculture should consider the likely profitability of various contained and on-bottom culture systems, including the use of antipredator strategies. Impacts of Alternative Production Systems on Communities and Households Structured interviews should be conducted with watermen and coastal community members, during which they are provided with descriptions of the management options and alternative production systems

OCR for page 232
Nonnative Oysters in the Chesapeake Bay and in which their opinions about the likely effects of the various combinations of management structure and production system are solicited. Information gained in the interviews will be useful in modeling the impacts of different management options and production systems on households and communities. These outcomes will depend in part on the economic consequences but also depend on whether the production systems associated with the options are compatible with current sociocultural norms and household production patterns. In addition to structured and systematic interviews, existing literature on changes in fishery production systems should be reviewed for information on the effects on fishers, processors (including workers), and socioeconomic and cultural characteristics of local communities. Cost Minimization Model While development of a comprehensive risk assessment model is daunting, development of a model to minimize the conditional costs of meeting biological risk assessment objectives is relatively straightforward and should be pursued. Although this approach would not integrate the full suite of risks and would not address risk tradeoffs, it would provide a criterion for selecting among alternative management decisions with similar levels of risk. For example, if the risk assessment model suggested that two alternatives had equal but acceptably low likelihoods of the unintended establishment of reproductive populations of C. ariakensis, managers could select the alternative that resulted in the least adverse impacts on watermen and fishery-dependent communities. Restoration Activities The proposed restoration activities should be assessed for probable level of success and the near- and intermediate-term economic consequences posed for watermen. The analysis should include expected net benefits and the variance of expected net benefits for harvesting and processing sectors in Maryland and Virginia for probable levels of recovery at different time points on the recovery schedule. Establish an Ongoing Economic and Sociocultural Data Collection Program The ability of social scientists to predict or evaluate the outcomes of contemplated management actions is impaired by a lack of baseline data and a lack of postimplementation data. The contemplated actions are likely to engender substantial changes in the economic organization of

OCR for page 232
Nonnative Oysters in the Chesapeake Bay the fishery and fishing communities. Therefore, the states of Virginia and Maryland should establish programs to collect baseline economic and sociocultural data. Such data should include economic information on production costs, including capital and labor expenditures, market trends and marketing practices, and changes in economic strategies and decision making in response to changes in the fishery. Sociocultural information should be collected on household- and community-level responses to changes in the oyster fishery and how such changes modify traditional sociocultural norms of such communities. The collection of economic and sociocultural data should be coordinated to maximize integration and complementarity. The data should be collected at different levels of scale, ranging from baywide to subregions and communities where existing industry structures (e.g., public versus leased), ecological conditions (e.g., salinity), and harvesting practices (e.g., power dredging versus patent tonging) could result in different sociocultural and economic consequences. Without good baseline data and consistent data collection over the next 5 to 10 years, it is unlikely that the effects of management action can be separated from the effects of unrelated changes in the fishery. While there is a tradition of this type of observation in some social sciences, there have been few longitudinal studies of fisheries. This research program could be organized through local Sea Grant offices or through a multistate entity but should be designed and budgeted for the full 5- to 10- year period with research conducted by a team of social scientists.