How to avoid knee tunnel convergence when performing a combined anterior cruciate ligament reconstruction and lateral extraarticular tenodesis utilizing the antero medial window

The anterolateral structures of the knee have been demonstrated to have a significant impact on reducing rotational instability and the forces applied to the anterior cruciate ligament reconstruction (ACL) graft after surgical reconstruction. Combined ACL reconstruction and lateral extraarticular tenodesis are being performed at an increasing number due to its promising outcome in properly indicated patients. However, tunnel convergence in combined ACLR and lateral extraarticular tenodesis can lead to graft damage and possible failure defeating the purpose of this very effective technique. This technical note describes how to avoid knee tunnel convergence when performing a combined ACL reconstruction with lateral extraarticular tenodesis utilizing the “Antero medial window”

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

A Comparison Of Dredge And Patent Tongs For Estimation Of Oyster Populations

Exploited oyster stocks on public grounds in Virginia waters are subject to regular surveys effected using a traditional oyster dredge and, more recently, patent tongs. Dredges provide semiquantitative data, have been used with consistency over extended periods (decades), and provide data on population trends. Surveys with patent tongs provide absolute quantification (number of individuals per unit area) of oyster stocks but are more labor intensive. Absolute quantification of dredge data is difficult in that dredges accumulate organisms as they move over the bottom, may not sample with constancy throughout a single dredge haul, and may fill before completion of the haul thereby providing biased sampling. Selectivity of dredges versus patent tongs with respect to oyster demographics has not been rigorously examined. The objective of this study is to compare demographic oyster data collected at the same sites in the same years from both gear types. Data for the study were taken from 1993 to 2001 surveys conducted in the James River, Virginia, by the Virginia Institute of Marine Science and the Virginia Marine Resources Commission wherein the same stations were sampled by both techniques. Dredge surveys give data in oysters per bushel and assume no selective retention of live oysters with respect to shell substrate by the dredge. Patent tong surveys provide data as per tong estimates of oysters by size class and shell by volume. The hydraulically operated, 1-m square tong used in VMRC/VIMS surveys is designed to sample on and below the reef surface and include elements of buried shell that are probably not well sampled by a dredge, although the sampling ensures collection of all oysters within the tong mouth. Oysters collected by both gear types were classified as small (25-75 mm) or market (\u3e75 mm SL) for comparisons across methods. Shell volumes collected in patent tong surveys were standardized to bushel increments assuming 35.28 L of shell per bushel. The summary plots of mean values from 1993 to 2001 and 1998 to 2001 illustrate differences related to sampling gear. More shell per unit oyster (lower bushel counts) are observed in a patent tong sample. The appropriate model for attempting to fit a predictive line is open to debate, and will be influenced by patent tong penetration as determined by the degree of consolidation of the underlying substrate. The available data do not strongly support the ability to predict a relationship between dredge and patent tong population estimates at this time

Northern Quahog (Hard Clam) Mercenaria Mercenaria Abundance And Habitat Use In Chesapeake Bay

Recent (2001-2002) surveys of hard clam Mercenaria mercenaria density and distribution, using patent tongs in a stratified random design (n = 7,358 stations) in lower Chesapeake Bay are not consistent with historic descriptions of clam habitats and densities. The highest average densities observed, up to 3.1 clams m(-2), were in the lower James River. The highest modern average density observed is half that of clam densities commonly observed in these same habitats during the early 1970s. Current distribution is significantly affected by water depth and substrate composition. Hard clam density in Chesapeake Bay is positively associated with increasing sediment grain size; 78% of all clams collected were found in shell or sand habitats. However, 44% of sand habitats and 54% of shell habitats were unoccupied suggesting that even habitat types that typically support higher clam densities may currently be underused

Expanding Virginia’s oyster industry while minimizing user conflict

This study seeks to assess the sustainability of the public oyster fishery and the expansion of hatchery dependent oyster aquaculture in the Virginia portion of the Chesapeake Bay. Previous analyses have suggested that limitations in available shell resources will ultimately drive the future of the public fishery. The expansion of intensive aquaculture, already apparent in the Bay, suggests sustainability will be contingent upon the availability of bottom space and/or a shift in practices that minimize user conflict in leased areas

Oyster (Crassostrea Virginica, Gmelin 1791) Population Dynamics On Public Reefs In The Great Wicomico River, Virginia, USA

We describe oyster population trends in the Great Wicomico River, VA, from 2000 through 2009 using quantitative fishery independent survey data collected using a stratified random design. The seven public reefs examined cover a total of 2.8 X 10(5) m(2) and vary in individual size from 1.36 X 10(4) to 7.16 X 10(4) m(2). The river is functionally divided by a sand spit into upriver and downriver regions. Oyster densities on the upriver reefs were typically an order of magnitude higher than densities on the downriver reefs within the same time period. Throughout the system, the highest observed densities were coincident with high annual recruitment events (2002, 2006). Recruitment events were usually followed by high mortality, with small percentages of the population reaching \u3e= 3 y of age. A predictive stock recruit relationship is absent; rather, population demographics appear to be dominated by periodic high recruitment events. In the absence of seed removal, biomass maxima follow 1-2 y after recruitment maxima. Standing stock for the system varied between 1.56 X 10(6) g and 3.63 X 10(7) g in 2005 and 2006. Year-specific age-at-length relationships were estimated from demographics data. Length demographics were recast as age demographics to estimate mortality. Observed proportional mortality between young of the year and age 2 oysters was approximately 0.88 for the 2006-y class, which is slightly higher than the 0.62-0.71 observed for the 2007-y class. The ability to estimate age specific mortality accurately allows the construction of shell (habitat) budgets for the individual reef systems. The Great Wicomico oyster population appears to be maintained by episodic and extraordinary recruitment in the face of high mortality the latter driven by disease (predominantly Perkinsus marinus) epizootics. The shell resource is modest, equivalent to little more than a monolayer several centimeters thick. Over short timescales (years), the available shell resource oscillates in concert with mortality. The shell accretion rate on upriver reefs is consistently 4-5 times greater than that observed on downriver reefs. Periodic modest shell planting has maintained the habitat base (the shell resource) throughout the system over decadal scales

Management Of The Piankatank River, Virginia, In Support Of Oyster (Crassostrea Virginica, Gmelin 1791) Fishery Repletion

The Piankatank River is a trap-type estuary on the western shore of Chesapeake Bay that has been managed for seed oyster production since 1963. Market oyster production in the river is minimal. Repletion efforts include shell planting and seed removal. We describe sequential changes in population demographics and habitat in relation to repletion activities on eight Piankatank River public oyster reefs from 1998 through 2009. Two reef groups (northern and southern) may be distinguished by density (oysters/m(2)), biomass (e dry tissue weight), and shell volume (L/m(2)) data. Age-at-length relationships were estimated from demographic data using a quadratic model. Observed mortality rates were high, and age 3+ oysters were essentially absent. A strong recruitment signal was observed in 1999 and 2002. Between 1998 and 2009, about 30% of the live oysters in the river were harvested as seed, corresponding to similar to 7.5% of the total shell base in an average year. Typically, for every 5 bushels of shell planted, 1 bushel of seed was harvested (20% return). Even with shell planting (similar to 10 L/m(2)/y), the river shell budget showed a deficit with respect to the accretion rate required to balance sea level rise and natural degradation processes. During the study period, the mean river recruit-to-stock ratio was similar to 4. The unusual and consistently high recruit-to-stock ratios suggest that management for modest continuous seed removal may be accomplished without shell planting. Annual stock assessment to identify low recruitment years is recommended as a method to adjust annual seed harvest quotas

Expanding Virginia s oyster industry while minimizing user conflict - Interim report (Year 2 of 3)

This study seeks to assess the sustainability of the public oyster fishery and the expansion of hatchery dependent oyster aquaculture in the Virginia portion of the Chesapeake Bay. Previous analyses have suggested that limitations in available shell resources will ultimately drive the future of the public fishery. The expansion of intensive aquaculture, already apparent in the Bay, suggests sustainability will be contingent upon the availability of bottom space and/or a shift in practices that minimize user conflict in leased areas

Population Studies Of The Native Eastern Oyster, Crassostrea Virginica, (Gmelin, 1791) In The James River, Virginia, Usa

We describe oyster population trends in the James River, VA from 1993 through 2006 using quantitative fishery independent survey data collected using a stratified random design, The 23 reefs contained in the study area cover a total of 2.41 to 4.98 X 10(7) m(2). There is a marked pattern in density of oysters among X 10(7) m(2) and vary in individual size from 1.26 X 10(4) m(2) the reefs: during the Study period a small group of reefs comprising 5.4% of the total a rea consistently contained between 25.7 and 55.5% by number and 35.8 and 54.8% by biomass of the total oyster population. The highest density reefs exhibit, with very few exceptions, mean densities well in excess of 200 oysters m(-2), typically between 300 and 500 m(-2) with a single maximum value of 773 oysters m(-2) in 2002 coincident with the highest annual recruitment observed during the Study period. Recruitment events were usually followed by very high mortality with very small percentages of the population reaching ages \u3e= 3 y of age. A strong stock-recruit relationship is absent; rather population demographics appear to be dominated by periodic high recruitment events. Biomass maxima tended to lag one to two years after recruitment maxima. Standing stock for the total system varied between 1.07 X 10(8) g and 3.31 X 10(8) g (107 and 331 metric tonnes) in 2003 and 2005, respectively as the 2002 recruits grew and suffered mortality. Age-at-length relationships were estimated from demographics: using a July I birth date and a November 1 survey date giving lengths of 37.3 mm at 0.33 y, 58.9 mm at 1.33 y, 80.5 mm at 2.33 y, 102.1 mm at 3.33 y and 123.7 mm at 4.33 y Length demographics were recast as age demographics to estimate annual proportional mortality. Mean proportional mortality values for age 1 oysters range from a low of 0.2-0.4 to a high in excess of 0.7. Age 2 mean proportional mortality values range from a low of 0.41 to a high exceeding 0.75. The proportional mortality for age 3 and 4 y olds generally exceeded mean values of 0.6 with highest values approaching 0.95. In all cases, these values exceeded mortality estimates calculated using traditional box count methods by a considerable margin. The ability to accurately estimate age specific mortality allows the construction of shell (habitat) budgets for the individual reef systems. Shell half-life loss rate estimates in the most productive reefs is between 2 and 3 y and the population is maintained by the continual and extraordinary recruitment in the face of high mortality-the latter driven by disease (predominantly Perkinsus marinus) epizootics. The shell resource, even on the most productive reefs, is modest, equivalent to little more than a monolayer several centimeters thick. Individual reefs demonstrate remarkable stability as either high shell density + high population density associations (high:high) or low shell density + low Population density associations (low:low), even in the face of temporal population and demographic fluctuations associated with disease related mortality. The probability of Manipulating either shell and/or live oyster density to effect the transition of a low:low reef to a high:high reef is considered bleak in the face of extant recruitment and mortality patterns. The primary impediment 10 population expansion or rebuilding is high and uncontrolled mortality rather than a lack of recruitment. Given the large numbers of oysters in low salinity refugia that have the ability to contnually contribute to the larval pool, active selection against disease susceptible oysters on a system wide basis is unlikely

Oyster Planting Protocols To Deter Losses To Cownose Ray Predation

The utility of shell overlays to oyster (Crassostrea virginica) plantings as a cownose ray (Rhinoptera bonasus) predator deterrence mechanism was examined. Typical industry practice of oyster seed planting was followed in an experimental design employing treatment areas of 0.5-1.0 acre (0.2-0.4 hectare). Areas were prepared in the Lower Machodoc Creek, Virginia, by the initial application of shell to insure a stable substrate under planted seed oysters. Seed oysters were planted using standard industry methods. Experimental areas were located, two upstream and two downstream, of a constriction in the Lower Machodoc that dictated differing physical environments in the respective locations with downstream locations being more exposed to northeast wind-driven stresses and, historically, a greater incidence of ray predation. Once oysters were planted, two of the areas, one upstream and one downstream of the aforementioned constriction, were additionally treated with a shell overlay as a predation deterrent. Oyster seed were planted in the experimental plots in February 2012. Market oysters were harvested from the experimental plots in December 2013 and January 2014. Final harvest data demonstrated that shell overlays do not offer additional protection to planted oyster seed with respect to possible cownose ray predation. Evidence of predation in the form of characteristically broken oyster valves were recorded in all treatment areas. Concurrent stomach content analysis of rays captured at the study location and observations of fouling community associated with the cultured oysters taken during the harvest operation indicate broad dietary preferences for rays when such a variety exists in the foraging region. For rays, oysters are not the singular preferred diet item, although localized and intensive feeding on oysters remains an option with a wide foraging range. Areas without overlay demonstrated higher production than those with shell overlay. Shell overlays are not recommended as predator deterrents for cownose rays in large deployments of unprotected oyster seed