Fishery independent standing stock surveys of oyster populations in Virginia 1997

Extensive description of the Virginia oyster resource and history of its utilization has been given by Haven, Hargis and Kendall (1981), and more recently reviewed by Hargis and Haven (1988). These contributions, among many others, describe a state of continuing decline. The James River, Virginia has served as the focal point for the Virginia oyster industry for over a century, being the source of the majority of seed oysters that were transplanted for grow-out to locations within the Virginia portion of the Chesapeake Bay and much further afield in the Middle Atlantic states (Haven et al, 1981). The Rappahannock River in Virginia was, for many years, a source of large and valued oysters for both the shucking and half shell trade. Other subestuaries and embayments in the Virginia portion of the Chesapeake Bay have served variously as both seed oyster (e.g. the Great Wicomico and Piankatank Rivers) and market oyster (Mobjack Bay, Tangier Sound and Pocomoke Sound) sources for the once substantial historical fishety. Until the initiation of the current project with suppmt of the Chesapeake Bay Stock Assessment Committee of NOAA (hereafter CBSAC) there was little effort to estimate standing stocks of oysters in the Virginia subestuaries, especially the James and Rappahannock Rivers. Continuing losses of productive oyster reef over the past 35 years to Haplosporidium nelsoni, commonly known as MSX, and Perkinsus marinus, commonly known as Dermo , in the higher salinity regions of the Bay and the subestuaries, combined with increased fishing pressure on all remaining stocks, have emphasized the need for working estimates of standing stock. This need has been further exaggerated in the James River by a change in emphasis in the past decade from the harvesting of seed oysters to larger market oysters, and the reduction in size limit of the latter from three to two-and-one-half inches maximum dimension for the 1988 through 1994 public oyster fishing seasons. The fishery continues to exploit the limited remaining broodstock from the James River in order to retain a viable fishery for market oysters, while simultaneously threatening the long term future of the river as the only functional seed producing location in the Virginia portion of the Chesapeake Bay. (more ..

Fishery independent standing stock surveys of oyster populations in the Virginia sub estuaries of the Chesapeake Bay and a comparison with continuing estimates obtained from fishery dependent data

Extensive description of the Virginia oyster resource and history of its utilization has been given by Haven, Hargis and Kendall (1981), and more recently reviewed by Hargis and Haven (1988). These contributions, among many others, describe a state of continuing decline. To facilitate resource management a fishery independent survey was proposed to and subsequently supported by the Chesapeake Bay Stock Assessment Committee in 1993. This report covers activity on that program for the period October of 1993 through September of 1994. Spatial variability in distribution of oysters within an oyster reef system, and distribution of reefs in the intertidal and/or subtidal regions complicate fishery independent estimation of standing stock. By contrast, fishery dependent estimates of oyster standing stock can be made, where adequate data on effort and temporal changes in landings exist, through application of Leslie-DeLury regression analysis (Barber and Mann, 1991). Intensive, fishery independent estimates are rare but pivotal to examination of spawning capabilities of broodstock supporting commercial fisheries and related requirements for establishment of fishery catch quotas. The James River, Virginia has served as the focal point for the Virginia oyster industry for over a century, being the source of the majority of seed oysters that were transplanted for grow-out to locations within the Virginia portion of the Chesapeake Bay and much further afield in the Middle Atlantic states (Haven et al, 1981). The Rappahannock River in Virginia was, for many years, a source of large and valued oysters for both the shucking and half shell trade. It is surprising that comparatively little effort has been previously expended to estimate standing stock in both the James and Rappahannock Rivers given the acknowledged need for such data in fishery management. Continuing losses of productive oyster reef over the past three decades to Haplosporidium nelsoni, commonly known as MSX, and Perkinsus marinus, commonly known as Dermo , in the higher salinity regions of both rivers, combined with increased fishing pressure on all remaining stocks, have emphasized the need for working estimates of standing stock. This need has been further exaggerated in the James River by a change in emphasis in the past decade from the harvesting of seed oysters to larger market oysters, and the reduction in size limit of the latter from three to two-and-one-half inches maximum dimension (although this action was reversed with an increase in minimum market size to three inches for the 1994-1995 season). The fishery is now facing the dilemma of exploiting the limited remaining broodstock from the James River in order to retain a viable fishery for market oysters, while simultaneously threatening the long term future of the river as a seed producing location

Fishery independent standing stock surveys of oyster populations in Virginia 1995

Extensive description of the Virginia oyster resource and history of its utilization has been given by Haven, Hargis and Kendall (1981), and more recently reviewed by Hargis and Haven (1988). These contributions, among many others, describe a state of continuing decline. The James River, Virginia has served as the focal point for the Virginia oyster industry for over a century, being the source of the majority of seed oysters that were transplanted for grow-out to locations within the Virginia portion of the Chesapeake Bay and much further afield in the Middle Atlantic states (Haven et al, 1981 ). The Rappahannock River in Virginia was, for many years, a source of large and valued oysters for both the shucking and half shell trade. It is surprising that comparatively little effort has been previously expended to estimate standing stock in both the James and Rappahannock Rivers given the acknowledged need for such data in fishery management. Continuing losses of productive oyster reef over the past three decades to Haplosporidium nelsoni, commonly known as MSX, and Perkinsus marinus, commonly known as Dermo , in the higher salinity regions of both rivers, combined \vith increased fishing pressure on all remaining stocks, have emphasized the need for wodcing estimates of standing stock. This need has been further exaggerated in the James River by a change in emphasis in the past decade from the harvesting of seed oysters to larger market oysters, and the reduction in size limit of the latter from three to two-and-one-half inches maximum dimension (although this action was reversed with an increase in minimum market size to three inches for the 1994-1995 season). The fishery continues to exploit the limited remaining broodstock from the James River in order to retain a viable fishery for market oysters, while simultaneously threatening the long term future of the river as the only functional seed producing location in the Virginia portion of the Chesapeake Bay. (more...

Oyster Restoration Efforts in Virginia

Long-term restoration of the Virginia Oyster resource has been assisted by a series of governmental and regulatory initiatives. Following the 1990 Blue Ribbon Panel the Virginia Marine Resources Commission set as goals that the oyster resources and oyster fishery would be so managed as to achieve (a) no net loss of existing standing stock of the native oyster over the next five years, and (b) a doubling of the existing standing stock of the native oyster over the next ten years. The 1994 Chesapeake Bay Aquatic Reef Plan and Oyster Fishery Management Plan both recommended the creation of 5,000 acres (2024 hectares) of oyster reef habitat during the 1995-2000 period. Practical progress toward this goal has been made through the development of several programs including direct application of substrate (cultch) to extant oyster reefs to facilitate settlement and recruitment, enhancement of reefs of the Seaside of the Eastern Shore by exhumation of buried shell, and construction of elevated reef structures in the Virginia subestuaries of the Chesapeake Bay. Efforts in the James River have included subtidal berm type structures capped with shell and a reef constructed entirely of shell. A shell reef has been constructed in the Piankatank River, and construction of several more is planned. All reefs remain as brood stock sanctuaries. Continuing management is supported by quantitative stock assessment.https://scholarworks.wm.edu/vimsbooks/1088/thumbnail.jp

When Shape Matters: correcting the ICFs to derive the chemical abundances of bipolar and elliptical PNe

The extraction of chemical abundances of ionised nebulae from a limited spectral range is usually hampered by the lack of emission lines corresponding to certain ionic stages. So far, the missing emission lines have been accounted for by the ionisation correction factors (ICFs), constructed under simplistic assumptions like spherical geometry by using 1-D photoionisation modelling. In this contribution we discuss the results (Goncalves et al. 2011, in prep.) of our ongoing project to find a new set of ICFs to determine total abundances of N, O, Ne, Ar, and S, with optical spectra, in the case of non-spherical PNe. These results are based on a grid of 3-D photoionisation modelling of round, elliptical and bipolar shaped PNe, spanning the typical PN luminosities, effective temperatures and densities. We show that the additional corrections --to the widely used Kingsburgh and Barlow (1994) ICFs-- are always higher for bipolars than for ellipticals. Moreover, these additional corrections are, for bipolars, up to: 17% for oxygen, 33% for nitrogen, 40% for neon, 28% for argon and 50% for sulphur. Finally, on top of the fact that corrections change greatly with shape, they vary also greatly with the central star temperature, while the luminosity is a less important parameter.Comment: Oral contribution (4 pages, 2 figures) to IAU Symposium 283: "Planetary Nebulae: An Eye to the Future" held in Puerto de la Cruz, Tenerife, Spain in July 25th-29th 201

Oyster Reef Habitat Restoration : a synopsis and synthesis of approaches; proceedings from the symposium, Williamsburg, Virginia, April 1995

This volume has its origin in a symposium held in Williamsburg, VA in April 1995, though most of the chapters have been significantly revised in the interim. The primary purpose of the symposium was to bring together state fisheries managers involved in fisheries-directed oyster enhancement and research scientists to refine approaches for enhancing oyster populations and to better develop the rationale for restoring reef habitats. We could hardly have anticipated the degree to which this been successful. In the interim between the symposium and the publication of this volume the notion that oyster reefs are valuable habitats, both for oysters and for the other ecosystem services they provide, has been gaining wider acceptance. . . . Table of Contents Introduction and Overview by Mark W. Luckenbach, Roger Mann and James A. Wesson Part I. Historical Perspectives Chapter 1 - The Evolution of the Chesapeake Oyster Reef System During the Holocene Epoch by William J. Hargis, Jr. Chapter 2 - The Morphology and Physical Oceanography of Unexploited Oyster Reefs in North America by Victor S. Kennedy and Lawrence P. Sanford Chapter 3 - Oyster Bottom: Surface Geomorphology and Twentieth Century Changes in the Maryland Chesapeake Bay by Gary F. Smith, Kelly N. Geenhawk and Dorothy L. Jensen Part II. Synopsis of Ongoing Efforts Chapter 4 - Resource Management Programs for the Eastern Oyster, Crassostrea virginica,in the U.S. Gulf of Mexico ...Past, Present and Future by Richard L. Leard, Ronald Dugas and Mark Benigan Chapter 5 - Oyster Habitat Restoration: A Response to Hurricane Andrew by William S. Perret, Ronald Dugas, John Roussel, Charles A. Wilson, and John Supan Chapter 6 - Oyster Restoration in Alabama by Richard K. Wallace, Kenneth Heck and Mark Van Hoose Chapter 7 - A History of Oyster Reef Restoration in North Carolina by Michael D. Marshall, Jeffrey E. French and Stephen W. Shelton Chapter 8 - Oyster Restoration Efforts in Virginia by James Wesson, Roger Mann and Mark Luckenbach Part Ill. Reef Morphology and Function - Questions of Scale Chapter 9 - South Carolina Intertidal Oyster Reef Studies: Design, Sampling and Focus for Evaluating Habitat Value and Function by Loren D. Coen, David M. Knott, Elizabeth L. Wenner, Nancy H. Hadley, Amy H. Ringwood and M. Yvonne Bobo Chapter 10 - Small-scale Patterns of Recruitment on a Constructed Intertidal Reef: The Role of Spatial Refugia by Ian K. Bartol and Roger Mann Chapter 11 - Perspectives on Induced Settlement and Metamorphosis as a Tool for Oyster Reef Enhancement by Stephen Coon and William K. Fitt Chapter 12 - Processes Controlling Local and Regional Patterns of Invertebrate Colonization: Applications to the Design of Artificial Oyster Habitat by Richard W. Osman and Robert B. Whitlatch Chapter 13 - Reefs as Metapopulatons: Approaches for Restoring and Managing Spatially Fragmented Habitats by Robert B. Whitlatch and Richard W. Osman Chapter 14 - Application of Landscape Ecological Principles to Oyster Reef Habitat Restoration by David B. Eggleston Chapter 15 - Use of Oyster Reefs as a Habitat for Epibenthic Fish and Decapods by Martin H. Posey, Troy D. Alphin, Christopher M. Powell and Edward Townsend Chapter 16 - Are Three Dimensional Structure and Healthy Oyster Populations the Keys to an Ecologically Interesting and Important Fish Community? by Denise L. Breitburg Chapter 17 - Materials Processing by Oysters in Patches: Interactive Roles of Current Speed and Seston Composition by Deborah Harsh and Mark W. Luckenbach Chapter 18 - Oyster Reefs as Components in Estuarine Nutrient Cycling: fucidental or Controlling? by Richard F. Dame Part IV. Alternative Substrates Chapter 19 - Use of Dredged Material for Oyster Habitat Creation in Coastal Virginia by Walter I. Priest, III, Janet Nestlerode and Christopher W. Frye Chapter 20 - Alternatives to Clam and Oyster Shell as Cultch for Eastern Oysters by Haywood, E. L., III, T. M. Soniat and R. C. Broadhurst, III Chapter 21 - Dredged Material as a Substrate for Fisheries Habitat Establishment in Coastal Waters by Douglas Clarke, David Meyer, Allison Veishlow and Michael LaCroix Part V. Management Options and Economic Considerations Chapter 22 - Managing Around Oyster Diseases in Maryland and Maryland Oyster Roundtable Strategies by Kennedy T. Paynter Chapter 23 - Chesapeake Bay Oyster Reefs, Their Importance, Destruction and Guidelines for Restoring Them by William J. Hargis, Jr. and Dexter S. Haven Chapter 24 - Economics of Augmentation of Natural Production Using Remote Setting Techniques by John E. Supan, Charles A. Wilson and Kenneth J. Robert

Comparison of Crassostrea virginica Gmelin (Eastern Oyster) Recruitment on Constructed Reefs and Adjacent Natural Oyster Bars over Decadal Time Scales

Since 1993, oyster reef replenishment efforts in the Virginia portion of the Chesapeake Bay have relied heavily on construction of oyster shell reefs with enhanced vertical relief. We evaluated the performance of six reefs constructed in proximity to natural subtidal oyster bars by comparing recruit densities (spat m ^ where spat are young-of-the-year oysters with shell heights less than 50 mm) between habitats. Recruitment was higher on the reefs than bars during the first 1-3 yr post-construction, usually by at least an order of magnitude. Within 7 yr, recruitment was similar between reef-bar pairs although both reefs and bars received additions of shell, live oysters, or both during the study period. At decadal time scales, constructed oyster reefs did not show enhanced recruitment relative to adjacent natural oyster bars. The rapid decline in reef recruitment post-construction is likely related to three processes: (i) shell degradation by taphonomic processes, (ii) biofouling that occludes the shell surface to recruitment, and (iii) inability of extant oysters on the reef to produce new shell at a rate commensurate with losses to (i) and (ii). There appears to be a requirement for continued replenishment activity to maintain the shell base on these reefs, contrary to the dynamics of a healthy natural oyster population. The similarity in recruitment between constructed reefs and natural bars at deeadal time scales suggests that subtidal shell plants or shell additions to natural bars may be a more cost-effective repletion strategy because they provide equal population enhancement per unit area