Dépôts récents

  • Preliminary Stock Structure of Coastal Bottlenose Dolphins along the Atlantic Coast of the US

    Southeast Fisheries Science Center, National Marine Fisheries Service (U.S.) (2001-06)
    Recent analyses have identified multiple stocks of bottlenose dolphins along the Atlantic coast from New Jersey to central Florida. Although drawing stock boundaries is confounded by the migratory pattern of the northernmost stock and by the unequal distribution of samples both spatially and temporally, results to date indicate the likelihood of a high level of structuring. In order to estimate abundance, the offshore range of the coastal morphotype of bottlenose dolphin also has been tentatively identified. That range is different north and south of Cape Hatteras; north of Cape Hatteras, evidence suggests that the coastal morphotype generally inhabits a range from the coast to 12km from shore, while south of Cape Hatteras, the range extends to 27km. Using both sets of results (latitudinal and longitudinal), management units can be defined for the purpose of evaluating the potential effects of fisheries mortality: 1. Northern Migratory Unit: In summer, this stock is found primarily from the NC/VA state line to the northern limit of the range (NJ or NY). In winter, this stock migrates out of the northern coastal areas and at least some of the animals are found off the coast of NC, where they spatially overlap with the northern and southern NC units. 2. Northern NC Unit: In summer, this unit consists of dolphins along the coast of NC from Cape Lookout to the VA/NC line and dolphins that reside in northern estuaries in this region. There is some evidence of dolphins moving between estuaries and the coast. There may also be spatial overlap between this unit and the southern NC unit in summer, at least in the estuaries near Cape Lookout. In winter, this unit occurs along the coast or estuaries of NC, where it spatially overlaps with the migratory unit and the southern NC unit. 3. Southern NC Unit: In summer, dolphins in this unit are found primarily along the coast of NC from south of Cape Lookout, NC, to Murrell's Inlet, SC. There may also be spatial overlap between this unit and the northern NC unit in summer, at least in the estuaries near Cape Lookout. In winter, these dolphins are assumed to be in the same areas, where they may spatially overlap with the migratory unit and with the Northern NC unit. 4. South Carolina Management Units: This management unit encompasses dolphins south of Murrell’s Inlet, SC, (the southern NC Unit) and the SC/GA state line. Seasonal movements that might result in spatial overlap between this stock and any others have not been defined. 5. Georgia Management Unit: This management unit encompasses dolphins in coastal and estuarine waters of Georgia. Seasonal movements that might result in spatial overlap between this stock and any others have not been defined. 6. Northern Florida Management Unit: This management unit includes dolphins from the FL/GA state line to the north end of the Indian/Banana River Lagoon system. 7. Central Florida Management Unit: This management unit begins south of the northern management unit and has an undefined southern boundary because of lack of information south of the Indian/Banana River system. However, consistent with results from areas to the north, it is precautionary to assume that this stock does not range as far south as southern Florida.
  • Taxonomic review and meristic variation in marine sculpins (Osteichthyes:Cottidae) of the northeast Pacific Ocean

    Howe, Kevin M.; Richardson, Sally L. (U.S. NOAA National Marine Service, Northwest and Alaska Fisheries Center, 1978-09-30)
    Within the northeast Pacific Ocean (Baja California to the Aleutian Islands), 40 genera comprising 90 species of sculpins (Cottidae) have been recorded; this includes two members of the freshwater genus Cottus which are often found in nearshore marine waters. The species are listed and their distributions are indicated. At present, only one family, Cottidae, should be recognized for the sculpins. Each genus is discussed in terms of taxonomic problems and affinities and each is also diagnosed, indicating differentiating characteristics. Some genera should be synonymized and these are indicated although no formal synonymies are proposed at this time. In addition, other genera need to be studied as they appear closely related to other genera and might be synonymized without any loss of information. The species in some genera (i.e. Artediellus, Hemitripterus, Icelinus, Icelus, Malacocottus, Myoxocephalus, Triglops) are in serious need of study. Some of the species within these genera, as well as many species in other genera are noticably rare in museum collections. Each species within the northeast Pacific is also diagnosed and comments on depth distribution and relative rarity are provided. Meristic data compiled from museum specimens is provided for each genus as well as each species. Artificial keys to the cottid genera and cottid species in the northeast Pacific Ocean are included.
  • A science-based seagrass survey window for coastal construction project planning in Florida

    Karazsia, Jocelyn (NOAA National Marine Fisheries Service, Southeast Region, 2010-05-01)
    A variety of construction activities occur in or near estuarine and coastal waters of Florida within habitats that may support seagrass. Resource managers have a need for a science-based seagrass survey window for Florida to ensure that habitats are adequately mapped and characterized prior to authorizing the destruction or modification of the habitat. The development of a survey window requires a balance between physical factors that maximize the ability to detect seagrass during sampling (essentially water clarity) and the time of year that supports peak biomass and distribution. Of the seven seagrass species found in Florida, two species exhibit greater seasonality: Halophila decipiens and Halodule wrightii. Several publications were synthesized that refer to the seasonality of seagrass. Based on this review and consultation with leading seagrass scientists, surveys for these seagrass species should occur June 1 through September 30. Results from surveys conducted outside this window will require careful evaluation given the likelihood that seagrass distribution or extent is underrepresented. This recommendation differs from but is not in conflict with recommendations from NMFS Protected Resources Division for Johnson's seagrass, Halophila johnsonni, which exhibits a life history that makes year-round sampling less problematic than it is for Halophila decipiens and Halodule wrightii. Because Halophila decipiens and Halodule wrightii are within the range of Halophila johnsonii, conducting surveys within the June 1 to September 30 window could eliminate the need for multiple surveys.
  • Growth and age study of Pacific hagfish (Eptatretus stoutii) off the central California coast

    Nakamura, Royden (California Polytechnic State University, 1994-03-07)
    The recent development of a short term, but very intense fishery for Pacific hagfish (Eptatretus stoutii) on the Pacific Coast of North America prompted concern over the absence of management and conservation guidelines for this species. However, very little is known of the biology of hagfish, particularly with regard to information applicable to fishery resource management. Growth and population age-size structure data are among critical categories of information that are non-existent to date. This project obtained primary growth information from field and laboratory studies as well as comprehensive population size composition data.
  • Estimates of cetacean abundance in the northern Gulf of Mexico from vessel surveys

    Hansen, Larry J.; Mullin, Keith D.; Roden, Carol L. (National Marine Fisheries Service, Southeast Fisheries Science Center, 1995)
    The Southeast Fisheries Science Center (SEFSC) initiated annual, vessel-based visual sampling surveys of northern Gulf of Mexico marine mammals in 1990. The primary goal of these surveys was to meet Marine Mammal Protection Act requirements for estimating abundance and monitoring trends of marine mammal stocks in United States waters. The surveys were designed to collect: 1) marine mammal sighting data to estimate abundance and to determine distribution and diversity; and 2) environmental data to evaluate factors which may affect the distribution, abundance and diversity of marine mammals. The analyses for abundance estimation from the 1991-1994 surveys are presented in this report.
  • Preliminary estimates of cetacean abundance in the northern Gulf of Mexico, and of selected cetacean species in the U.S. Atlantic Exclusive Economic Zone from vessel surveys

    Hansen, Larry J.; Mullin, Keith D.; Roden, Carol L. (National Marine Fisheries Service, Southeast Fisheries Science Center, 1995)
    The Southeast Fisheries Science Center (SEFSC) initiated annual, vessel-based visual sampling surveys of northern Gulf of Mexico marine mammals in 1990 and conducted a similar survey in U.S. Atlantic Exclusive Economic Zone (EEZ) waters from Miami, Florida, to Cape Hatteras, North Carolina, in 1992. The primary goal of these surveys was to meet Marine Mammal Protection Act requirements for estimating abundance and monitoring trends of marine mammal stocks in United States waters. The surveys were designed to collect: 1) marine mammal sighting data to estimate abundance and to determine distribution and diversity; and 2) environmental data to evaluate factors which may affect the distribution, abundance and diversity of marine mammals. The preliminary analyses for abundance estimation from the 1990-1993 surveys are presented in this report.
  • Report on the biology of Pacific hagfish, Eptatretus stouti and the development of its fishery in California

    Kato, Susumu (NOAA National Marine Fisheries Service, Southwest Region, 1990-08-03)
    Hagfish, often referred to as "slime eels", are familiar to most fishermen as pests that frequently devour fish caught by trap, hook, and gillnet. In the Republic of Korea (ROK or South Korea), however, hagfish are sought after as valuable fish not only for their edible flesh, but also for their skin, which is processed into leather used to make expensive purses, shoes, and other articles. In fact, because of a shortage of hagfish in the waters near the ROK, the leather industry there has started to import hagfish, first from Japan in the mid 1980's, then from the United States starting in 1988.This report describes the nascent fishery for Eptatretus stouti (Pacific hagfish) in California, and includes aspects of its life history. The hagfish industry in the ROK is also briefly described.
  • Abundance of cetaceans in the oceanic northern Gulf of Mexico from 2003 and 2004 ship surveys

    Mullin, Keith D. (NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, 2007-03)
    The Gulf of Mexico (GMx) is a subtropical marginal sea of the western North Atlantic Ocean with a diverse cetacean community. Ship-based, line-transect abundance surveys were conducted in oceanic waters (>200 m deep) of the northern GMx within U.S. waters (380,432 square km) during summer 2003 and spring 2004. Data from these surveys were pooled and minimum abundance estimates were based on 10,933 km of effort and 433 sightings of at least 17 species.The most commonly sighted species (number of groups) were pantropical spotted dolphin, Stenella attenuata (115); sperm whale, Physeter macrocephalus (85); dwarf/pygmy sperm whale, Kogia sima/breviceps (27); Risso’s dolphin, Grampus griseus (26); and bottlenose dolphin, Tursiops truncatus (26). The most abundant species (number of individuals; coefficient of variation) were S. attenuata (34,067; 0.18); Clymene dolphin, S. clymene (6,575; 0.36); T. truncatus (3,708; 0.42); and striped dolphin, S. coeruleoalba (3,325; 0.48). The only largewhales sighted were P. macrocephalus (1,665; 0.20) and Bryde’s whale, Balaenoptera edeni (15; 1.98). Abundances for other species or genera ranged from 57 to 2,283 animals. Cetaceanswere sighted throughout the oceanic northern GMx, and whereas many species were widely distributed, some had more regional distributions. Compared to abundance estimates for this area based on 1996-2001 surveys, the estimate for S. attenuata was significantly smaller (P <0.05) and that for the spinner dolphin, S. longirostris, appeared much smaller. Also, P. macrocephalus estimates were based on less negatively biased estimates of group-size using 90-minute counts during 2003 and 2004.
  • Feasibility of using sea surface temperature imagery to mitigate cheloniid sea turtle–fishery interactions off the coast of northeastern USA

    Braun-McNeill, Joanne; Sasso, Christopher R.; Epperly, Sheryan P.; Rivero, Carlos (2008)
    Endangered Species Research
    As sea turtles migrate along the Atlantic coast of the USA, their incidental capture in fisheries is a significant source of mortality. Because distribution of marine cheloniid turtles appears to be related, in part, to sea surface temperature (SST), the ability to predict water temperature over the continental shelf could be useful in minimizing turtle–fishery interactions. We analyzed 10 yr of advanced very high resolution radiometer (AVHRR) SST imagery to estimate the proportion of 18 spatial zones, nearshore and offshore of Hatteras, North Carolina, USA (35° N), to north of Cape Sable, Nova Scotia (44° N), at temperatures >10 to 15°C, by week. Detailed examples for 11°C, the temperature employed by some management actions in the study area, and for 14°C, the lowest temperature at which turtles were sighted by some studies in the area, demonstrate a predictable pattern of rapid warming in March and April, followed by rapid cooling in October and November, with nearshore waters warming more rapidly than those offshore. Of those loggerhead turtles Caretta caretta that stranded, were sighted, or were incidentally captured between Cape Hatteras, North Carolina, and Cape Cod, Massachusetts, those at lower latitudes occurred when 25% or more of the area reached a water temperature of 11°C, while those in the northern zones did not occur until 50% or more of the area had reached a water temperature of 14°C. This analysis provides a means of predicting marine cheloniid turtle presence, which can be helpful in regulating fisheries that seasonally interact with turtles.
  • Northeast Fisheries Observer Program manual, 2013

    NOAA Northeast Fisheries Science Center (NOAA/National Marine Fisheries Service, 2013)
    The National Marine Fisheries Service (NMFS) Northeast Fisheries Science Center (NEFSC) Fisheries Sampling Branch (FSB) collects, maintains, and distributes data for scientific and management purposes in the northwest Atlantic Ocean. FSB manages three separate but related observer programs: the Northeast Fisheries Observer Program (NEFOP), the Industry Funded Scallop (IFS) Observer Program, and the At Sea Monitoring (ASM) Program. For the purposes of this manual, “observers” refers to any observer/monitor working for the FSB.In 2011, FSB trained and deployed over 200 observers, provided coverage on a variety of fisheries, and completed over 15,000 sea days. Observed trips are required under many of the region's fishery management plans, and for some fisheries by other federal laws and authorities such as Amendment 16 and Framework 44, Magnuson-Stevens Fishery Conservation and Management Act, Marine Mammal Protection Act, the Endangered Species Act, the and the Sustainable Fisheries Act.The purpose of this guide is to provide FSB observers, as well as end users of NEFSC Observer Program data, with a detailed description of each data field collected. In addition to this manual, the NEFSC Observer Program Biological Sampling and Catch Estimation Manual provides summaries and tables intended to enable observers to quickly determine the correct sampling protocols and methods while at sea.This manual represents a revision of the data forms, collection procedures, and protocols described in the 1996 NEFSC Observer Program Manual. For documentation of other changes see Documentation of changes made to the NEFSC Fisheries Observer Program Manual, 2013.
  • Use of skeletochronological analysis to estimate the age of leatherback sea turtles Dermochelys coriacea in the western North Atlantic

    Avens, Larisa; Taylor, J. Christopher; Goshe, Lisa R.; Jones, T. Todd; Hastings, Mervin (2009)
    Endangered Species Research
    Although growth rate and age data are essential for leatherback management, estimates of these demographic parameters remain speculative due to the cryptic life history of this endangered species. Skeletochronological analysis of scleral ossicles obtained from 8 captive, known-age and 33 wild leatherbacks originating from the western North Atlantic was conducted to characterize the ossicles and the growth marks within them. Ages were accurately estimated for the known-age turtles, and their growth mark attributes were used to calibrate growth mark counts for the ossicles from wild specimens. Due to growth mark compaction and resorption, the number of marks visible at ossicle section tips was consistently and significantly greater than the number visible along the lateral edges, demonstrating that growth mark counts should be performed at the tips so that age is not underestimated. A correction factor protocol that incorporated the trajectory of early growth increments was used to estimate the number of missing marks in those ossicles exhibiting resorption, which was then added to the number of observed marks to obtain an age estimate for each turtle. A generalized smoothing spline model, von Bertalanffy growth curve, and size-at-age function were used to obtain estimates of age at maturity for leatherbacks in the western North Atlantic. Results of these analyses suggest that median age at maturation for leatherbacks in this part of the world may range from 24.5 to 29 yr. These age estimates are much greater than those proposed in previous studies and have significant implications for population management and recovery.
  • Population structure of island-associated dolphins: evidence from photo-identification of common bottlenose dolphins (Tursiops truncatus) in the main Hawaiian Islands

    Baird, Robin W.; Gorgone, Antoinette M.; McSweeney, Daniel J.; Ligon, Allan D.; Deakos, Mark H.; Webster, Daniel L.; Schorr, Gregory S.; Martien, Karen K.; Salden, Dan R.; Mahaffy, Sabre D. (2009)
    Marine Mammal Science
    Management agencies often use geopolitical boundaries as proxies for biological boundaries. In Hawaiian waters a single stock is recognized of common bottlenose dolphins, Tursiops truncatus, a species that is found both in open water and near-shore among the main Hawaiian Islands. To assess population structure, we photo-identified 336 distinctive individuals from the main Hawaiian Islands, from 2000 to 2006. Their generally shallow-water distribution, and numerous within-year and between-year resightings within island areas suggest that individuals are resident to the islands, rather than part of an offshore population moving through the area. Comparisons of identifications obtained from Kaua‘i/Ni‘ihau, O‘ahu, the “4-island area,” and the island of Hawai‘i showed no evidence of movements among these island groups, although movements from Kaua‘i to Ni‘ihau and among the “4-islands” were documented. A Bayesian analysis examining the probability of missing movements among island groups, given our sample sizes for different areas, indicates that interisland movement rates are less than 1% per year with 95% probability. Our results suggest the existence of multiple demographically independent populations of island-associated common bottlenose dolphins around the main Hawaiian islands.
  • Combining stable isotopes and skeletal growth marks to detect habitat shifts in juvenile loggerhead sea turtles Caretta caretta

    Snover, Melissa L.; Hohn, Aleta A.; Crowder, Larry B.; Macko, Stephen A. (2010)
    Endangered Species Research
    Understanding the phase and timing of ontogenetic habitat shifts underlies the study of a species’ life history and population dynamics. This information is especially critical to the conservation and management of threatened and endangered species, such as the loggerhead sea turtle Caretta caretta. The early life of loggerheads consists of a terrestrial egg and hatchling stage, a posthatchlingand juvenile oceanic, pelagic feeding stage, and a juvenile neritic, primarily benthic feeding stage. In the present study, novel approaches were applied to explore the timing of the loggerhead ontogenetic shift from pelagic to benthic habitats. The most recent years of somatic growth are recorded as annual marks in humerus cross sections. A consistent growth mark pattern in benthic juvenile loggerheads was identified, with narrow growth marks in the interior of the bone transitioning to wider growth marks at the exterior, indicative of a sharp increase in growth rates at the transitional growth mark. This increase in annual growth is hypothesized to correlate with the ontogenetic shift from pelagic to benthic habitats. Stable isotopes of carbon and nitrogen just interior and exteriorto the transitional growth mark, as well as stable isotopes from pelagic and benthic flora, fauna and loggerhead stomach contents, were analyzed to determine whether this transition related to a diet shift. The results clearly indicate that a dietary shift from oceanic/pelagic to neritic/benthic feeding corresponds to a transitional growth mark. The combination of stable isotope analysis with skeletochronology can elucidate the ecology of cryptic life history stages during loggerhead ontogeny.
  • Analyzing and mapping fish assemblages off central California, USA

    Morrison, Wendy; Claflin, Larry; Monaco, Mark; Turk, Teresa; Wilson-Vandenberg, Deb (2010)
    California Fish and Game
    This study describes fish assemblages and their spatial patterns off the coast of California from Point Arena to Point Sal, by combining the results of the multivariate analyses of several fisheries datasets with a geographic information system. In order to provide comprehensive spatial coverage for the areas of inshore, continental shelf, and continental slope, three fisheries datasets were analyzed: 1) Inshore: the California Department of Fish and Game dataset of fishery-dependent commercial passenger fishing vessel trips that targeted rockfish; 2) Continental Shelf: the National Marine Fisheries Service (NMFS) fishery-independent bottom trawls; and 3) Continental Slope: the NMFS fishery-independent bottom trawls on the continental slope. One-hundred seven species were analyzed. These species represented those captured in at least 5% of the fishing trips or trawls in at least one of the three data sets. We analyzed each of the three datasets separately, and the three sets of results were combined to define 28 species assemblages and 23 site groups. A species assemblage consisted of species caught together, whereas a site group consisted of fishing trips or trawl locations that tended to have the same species assemblages. At the scale of these datasets, 97% of all site groups were significantly segregated by depth.
  • 2007 biennial report to Congress on the progress and findings of studies of striped bass populations

    Shepherd, Gary R.; Hooker, Brian R.; Laney, R. Wilson; Meserve, Nichola; Jacobs, John (NOAA/National Marine Fisheries Service, 2007)
    The 1997 reauthorization of the Atlantic Striped Bass Conservation Act (Striped Bass Act) mandated biennial reports to Congress and to the Atlantic States Marine Fisheries Commission (Commission) from the secretaries of the Department of Commerce and the Department of the Interior concerning the progress and findings of studies of Atlantic striped bass (Morone saxatilis). The Striped Bass Act specifically requests updates on studies that include, but are not limited to: annual stock assessments, investigations on the causes of fluctuations in Atlantic striped bass populations, the effects of environmental factors on the recruitment, spawning potential, mortality, and abundance of Atlantic striped bass populations, and investigations of interactions between Atlantic striped bass and other fish. This document is the fifth such report to Congress and includes data available through 2007 with emphasis on the 2005 and 2006 calendar years.
  • Sensitivity of Lake Sturgeon population dynamics and genetics to demographic parameters [Powerpoint Slide]

    Schueller, Amy M.; Hayes, Daniel B. (2007)
    Lake sturgeon Acipenser fulvescens restoration is a priority throughout the Great Lakes basin, where sturgeon have been reduced to less than 1% of historic levels due to habitat degradation, overharvest, and fragmentation of spawning populations. The population parameters mostimportant to long-term lake sturgeon persistence are unknown.
  • Deriving acceptable biological catch from the overfishing limit: implications for assessment models

    Prager, Michael H.; Shertzer, Kyle W. (2010)
    North American Journal of Fisheries Management
    The recently revised Magnuson–Stevens Fishery Conservation and Management Act requires that U.S. fishery management councils avoid overfishing by setting annual catch limits (ACLs) not exceeding recommendations of the councils’ scientific advisers. To meet that requirement, the scientific advisers will need to know the overfishing limit (OFL) estimated in each stock assessment, with OFL being thecatch available from applying the limit fishing mortality rate to current or projected stock biomass. The advisers then will derive ‘‘acceptable biological catch’’ (ABC) from OFL by reducing OFL to allow for scientific uncertainty, and ABC becomes their recommendation to the council. We suggest methodology based on simple probability theory by which scientific advisers can compute ABC from OFL and thestatistical distribution of OFL as estimated by a stock assessment. Our method includes approximations to the distribution of OFL if it is not known from the assessment; however, we find it preferable to have the assessment model estimate the distribution of OFL directly. Probability-based methods such as this one provide well-defined approaches to setting ABC and may be helpful to scientific advisers as they translate the new legal requirement into concrete advice.
  • The nation's fisheries

    National Oceanic and Atmospheric Administration (U.S. Department of Commerce, National Oceanic and Atmospheric Administration, 1972)
    Brief NOAA pamphlet about U.S. fisheries. Includes illustrations of fish and fishing gear, and photographs of fishing vessels. (PDF has 5 pages.)
  • Age determination and age related factors in the teeth of Western North Atlantic bottlenose dolphins.

    Hohn, Aleta A. (1980)
    Scientific Reports of the Whales Research Institute
    Teeth were taken from 120 bottlenose dolphins, Tursiops truncatus, which had stranded on the mid-Atlantic coast of the United States. The number of annual growth layer groups (GLGs) for each animal was used to construct a growth curve. The growth rate of coastal North Atlantic Ocean Tursiops is similar to other cetaceans in having a high initial rate of growth, with no differences in growth between females and males. In females, the first dentinalGLG is thickest and is followed by GLGs which become progressively narrower. In males, the second GLG is thicker than the first; GLGs beyond number two become progressively smaller but at a slower rate than in females. In males and females, the translucent layer makes up proportionallylarger parts of the GLG as the animal ages, but in males the percent translucent layer remains constant at about 50% while in females it continues to increase up to about 70% of the GLG. These two factors, GLGs width and translucent layer width, indicate that the sex and age of the animal influence the deposition of GLGs. Incremental layers are also present, averaging 12 per GLG, and seem similar to incremental layers described in other marine mammals. A plot of the relationship of percent growth of the last GLG to time of death suggests that the deposition of GLGs is relatively constant, at least during the first half of the year, and that North Atlantic Ocean Tursiops give birth in the fall as well as in the spring. (PDF contains 31 pages.)
  • Analysis of growth layers in the teeth of Tursiops truncatus using light microscopy, microradiography, and SEM

    Hohn, Aleta A. (1980)
    Report of the International Whaling Commission
    Preliminary results show microradiography and scanning electron microscopy (SEM) to be more accurate methods of accessing growth layer groups (GLGs) in the teeth of Tursiops truncatus than transmitted light microscopy. Microradiography shows the rhythmic deposition of mineral as alternating radiopaque and radiolucent layers. It improves the resolution of GLGs near the pulp cavity in older individuals, better than either SEM or light microscopy. SEM of etched sections show GLGs as ridges and grooves which are easily counted from the micrograph. SEM also shows GLGs to be composed of fine incremental layers of uniform size and number which may allow for more precise age determination. Accessory layers are usually hypomineralized layers within the hypermineralized layer of the GLG and are more readily distinguishable as such in SEM of etched sections and microradiographs than in thin sections viewed under transmitted light. The neonatal line is hypomineralized, appearing translucent under transmittedlight, radiolucent in a microradiograph, and as a ridge in SEM. (PDF contains 6 pages.)

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