Fish recruitment is the result of the integration of small‐scale processes affecting larval survival over a season and large oceanic areas. A hydrodynamic model was used to explore and model these ...physical–biological interaction mechanisms and then to perform the integration from individual to population scales in order to provide recruitment predictions for fisheries management. This method was applied to the case of anchovy (Engraulis encrasicolus) in the Bay of Biscay (NE Atlantic). The main data available to investigate survival mechanisms were past growth (otolith) records of larvae and juveniles sampled at sea. The drift history of these individuals was reconstructed by a backtracking procedure using hydrodynamic simulations. The relationships between (real) growth variation and variations in physical parameters (estimated by hydrodynamic simulations) were explored along the individual trajectories obtained. These relationships were then used to build and adjust individual‐based growth and survival models. Thousands of virtual buoys were released in the hydrodynamic model in order to reproduce the space–time spawning dynamics. Along the buoy trajectories (representative of sub‐cohorts), the biophysical model was run to simulate growth and survival as a function of the environment encountered. The survival rate after 3 months of drift was estimated for each sub‐cohort. The sum of all these survival rates over the season constituted an annual recruitment index. This index was validated over a series of recruitment estimations. The modelling choices, model results and the potential use of the recruitment index for fisheries management are discussed.
•Individuals’ life-time growth trajectory is determined by early growth.•Age-0 growth has declined and is density-dependent for anchovy and sardine.•Large fish disappear within cohorts and this ...occurs even with low harvest rates.•Environmental variables have little effect of the magnitude of selection.•Different stock histories explain the different selection regimes both of species.
In many exploited marine fish species, older individuals within cohorts often have slower growth rates at age than their younger counterparts, a process generally attributed to fishing. However, environmental changes might also contribute to the selective disappearance of faster growing individuals because of the increasing constraints acting on growth in suboptimal environments. Using otoliths of anchovy and sardine collected each year in spring since 2000 in the Bay of Biscay, we measured individuals’ growth during age-0 and catch-up growth during age-1, and followed their changes in time from 2000 to 2018 to quantify the magnitude of selective mortality. We then determined whether the variations in growth and selective mortality were related to seasonal temperature, food quantity, stock biomass or stock harvest rate. In both species, there was a decline in growth during age 0 over time and a catch-up growth declined in anchovy. Density-dependence had a strong effect on growth in anchovy. In both species, there was a systematic selective disappearance of individuals with large growth at age-0 within each cohort and selection has changed over time to favour individuals with large catch-up growth in anchovy. Moreover, diversifying selection occurred for growth at age-0 in both species and catch-up growth in anchovy. In anchovy, years with high selective disappearance of large individuals, high catch-up growth and high diversifying selection were those in which the harvest rates were high (environmental variables having more limited effect). In sardine, the selective disappearance of large individuals was stronger in years with low food quantity and the magnitude of selection acting on growth was unrelated to this stock’s harvest rate. Though fishing exerted strong selection pressure in anchovy, selective mortality against large growth still occurred even at low harvest rates in both species, suggesting that this might be a natural process affecting these small pelagic forage fish species. Although anchovy and sardine have a similar trophic position, their selection regimes differed due to differences in their stock dynamics, environmental sensitivity, and fishing rate. It might therefore be hazardous to extrapolate the responses of single species to environmental and anthropogenic factors onto others.
The relation between growth and survival was investigated using the otolith growth data collected during repeated larval surveys (May–July) and a juvenile survey (September) undertaken in 1999 on ...anchovy spawning and nursery grounds in the Bay of Biscay (NE Atlantic). The paper describes the methodology for reading the larval and juvenile otoliths, for reconstructing the correspondence in space and time between juveniles and larvae using Lagrangian simulations, and for comparing the otolith growth rates among the reconstructed sub‐cohorts. Virtual buoys were released weekly on the grid of a three‐dimensional hydrodynamic model and their trajectories were tracked. The origin of an individual was determined by selecting the trajectory beginning on its hatching week and ending at the minimum distance of its sampling location on the sampling date. Larvae and juveniles with the same spatio‐temporal origin were selected and supposed to belong to the same sub‐cohorts. The surviving juveniles showed faster growth rates during their larval period than the pool of larvae they were estimated to originate from, which supports the idea of growth‐selective survival. Alternative interpretations (transport and gear selectivity) are discussed. Variations in otolith growth pattern also suggest a higher juvenile growth over the shelf break than in oceanic waters.
•The PELGAS integrated survey conducted since 2000 in spring in the Bay of Biscay is presented.•PELGAS objectives have switched from the study of the anchovy stock status to ecosystem ...monitoring.•Spatially-explicit data of the main pelagic ecosystem components have been collected since 2000.•Multidisciplinary collaborative working and enough vessel space were critical success factors.•Finding relevant common scales is essential to analyse ecosystem data within or across compartments.
The Pélagiques Gascogne (PELGAS) integrated survey has been developed by a multidisciplinary team of Ifremer and La Rochelle University scientists since 2000, joined by commercial fishermen in 2007. Its initial focus was to assess the biomass and predict the recruitment success of anchovy in the Bay of Biscay in spring. Taking advantage of the space and versatility of R/V Thalassa II, sampling has been progressively extended to other ecosystem components. PELGAS therefore further developed the second objective of monitoring and studying the dynamic and diverse Biscay pelagic ecosystem in springtime. The PELGAS survey model has allowed for the establishment of a long-term time-series of spatially-explicit data of the Bay of Biscay pelagic ecosystem since the year 2000. Main sampled components of the targeted ecosystem are: hydrology, phytoplankton, mesozooplankton, fish and megafauna. The survey now provides two main ecosystem products: standard raster maps of ecosystem parameters, and a time series dataset of indicators of the Bay of Biscay pelagic ecosystem state. They are used to inform fish stock and ecosystem-based management, and support ecosystem research. The present paper introduces the PELGAS survey, as a practical example of an integrated, vessel-based, ecosystem survey. The evolution of the PELGAS scientific team and sampling protocols are presented and analysed, to outline factors crucial to the success of the survey. Data and results derived from PELGAS are reviewed, to exemplify scientific questions that can be tackled by integrated ecosystem survey data. Advantages and challenges of the survey are discussed and put into the context of marine ecosystem surveys in the European Marine Strategy Framework Directive and the Common Fisheries Policy.
Spontaneous spinal epidural hematoma is a rare entity. We report four cases of nontraumatic spinal epidural hematomas observed from 1990 to 1994.
In two cases, the causes were determined to be an ...acquired coagulopathy and a vascular malformation; in the other two cases, no causes were detected. We reviewed 85 cases in the literature, with particular emphasis on the various causes detected (coagulopathy, vascular malformations, tumor) and the diagnostic methods used.
All the patients were investigated by computed tomography and magnetic resonance imaging and underwent surgery.
We considered the expression "nontraumatic epidural hematoma" to be less ambiguous than "spontaneous spinal epidural hematoma," which is the one that is usually used in the literature and corresponds to various definitions. In the absence of any signs suggestive of vascular malformation on magnetic resonance imaging, preoperative angiography is not essential and need not delay the surgical procedure, because the timing of the surgery, together with the preoperative clinical state, determines the quality of the clinical result.
•Exploration of energy density sources of variability: species, season, region, size.•Relationships between dry mass content and ED are strong but species specific.•Larger length, mass and ED at age ...in the English Channel than in the Bay of Biscay.•Sardine display larger energy reserves than anchovy.•Larger reserves are likely in link with larger spawning or maintenance costs.•A strong scaling of ED with size with a dome shape pattern for sardine.•Decrease of ED with size is discussed in link with feeding and spawning behaviours.
There is a growing interest in monitoring body condition of marine organisms in the context of the ecosystem approach to fisheries and global change. Fish condition is under the influence of environmental variability on seasonal scale, but also on longer timescales. It represents a good indicator of habitat quality or individual fitness, and is also a relevant parameter to evaluate energy transfer through the trophic chain. However, the sources of variability in fish condition need to be accurately understood and the significance of existing indices has to be correctly assessed. Here, we measured the energy density, a precise and global indicator of fish bioenergetic condition, for anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Bay of Biscay and the English Channel, based on an extensive sampling design in 2014. First, we investigated the well-documented relationship between percent dry mass and energy density, and showed that such relationship is species specific. Second, we observed distinct patterns in bioenergetic condition between anchovy and sardine. Both species display similar minimum values at size or age but maximum are significantly higher for sardine, reflecting a higher energy storage capacity that scales more strongly with size. Third, we confirmed the large seasonal variability in energy density of both species. In the Bay of Biscay, energy density values for anchovy and sardine (age 1+) are 5.7 and 5.9 kJ g−1 (wet weight) in spring and 6.8 and 7.9 kJ g−1 in autumn, respectively. Our results revealed that fish from the English Channel display significantly higher energy density values in autumn (9.8 kJ g−1 for anchovy and 10.5 kJ g−1 for sardine) than those from the Bay of Biscay. When combined with size and weight at age it appears clearly that, after age 1, fish from the northern region display larger growth and energy reserves. This likely results from a higher zooplankton productivity in the English Channel or/and a selection pressure towards faster growing and faster reserve building individuals, to be able to survive a longer winter than in the Bay of Biscay. Finally, we described a dome shaped evolution of energy density with body size in case of sardine. Increase with size has been well documented but not the decrease at largest sizes. Several mechanisms may explain such a pattern, i.e. increasing investment in spawning, shift in diet or a metabolic trade-off between temperature and food availability, with regard to maintenance requirements.
Occipitocervical fixation is used for the treatment of nontraumatic upper cervical instabilities. To date, plates have been fixed with screws or wires. However, these devices are not indicated in the ...treatment of patients with severe osteoporosis or in instances of significant thinning of the occipital bone. We performed a clinical trial of a new type of fixation that uses cervical interlaminar hooks and occipital claws with hooks or with screws (CCD type; Sofamor-Danek, Roissy, France) for the treatment of nontraumatic upper cervical instabilities.
Five women and one man ranging in age from 28 to 72 years (average age, 54 yr) were thus treated. The CCD type material had two rod plates and hooks allowing the proper placement of interlaminar and occipital claws. The occipital plate can also be directly screwed to the bone. Occipital hooks were used in four patients. The other two patients, who had occipitocervical congenital abnormalities that required an occipitocervical opening and an additional dural enlargement, underwent occipital screw fixation because of the previous opening of the foramen magnum. A cancellous iliac autograft allowed the usual fusion.
No postoperative complications were observed, and all patients experienced significant improvement of their neck pain. Four patients had neurological symptoms. The condition of two patients improved, and the condition of the other two stabilized.
This report confirms the interest of the CCD method to correct all types of upper cervical instabilities, even in cases of unusual thinning of the occipital bone or in osteoporotic states.
Petitgas, P., Doray, M., Massé, J., and Grellier, P. 2011. Spatially explicit estimation of fish length histograms, with application to anchovy habitats in the Bay of Biscay. - ICES Journal of Marine ...Science, 68: 2086-2095.
Fish length frequency histograms from research surveys are of prime importance for identifying habitats of different life stages, as well as for stock assessment. However, no method has thus far been available for mapping these histograms as spatially varying curves. Here, a procedure is applied to map spatially connected curves, and detail is given on how it can be applied to map the length frequency histograms. At each sample location, a fish length frequency histogram is given as a vector of non-independent values. The histogram is first modelled as a polynomial expansion on the basis of orthogonal polynomials. Then, the polynomial coefficients are mapped by co-kriging, after fitting a model of co-regionalization. The length frequency map is finally derived by linearly combining maps of polynomial coefficients. An estimation variance associated with the map is also derived. Maps of anchovy length distributions are produced by applying the method to midwater trawl length data from the PELGAS acoustic surveys in the Bay of Biscay. This novel approach extends the application of kriging techniques to curves or functions, opening new perspectives for mapping more complex information than just the values of fish density.
The aim of this study was to perform a multivariate analysis including clinical and biological prognostic factors on glial tumor outcome. Seventy-nine patients were analyzed (48 men and 31 women; ...mean age = 56 years, range = 16-77 years): 7 had a benign glial tumor (grades 1 and 2), 21 had an anaplastic glial tumor (grade 3), and 51 had a glioblastoma (grade 4). Median follow-up was 17.9 months for patients who survived (50 patients died). Biopsies were obtained at time of diagnosis (complete tumor resection in 62 patients and stereotaxic biopsies in 17 patients). Epidermal growth factor receptor (EGFR) was measured by a binding assay, and labeling index (LI) was measured by tritiated thymidine incorporation. EGFR varied from 4 to 73,110 fmol/mg protein (mean = 3912 fmol/mg protein; median = 374 fmol/mg protein; n = 79). LI varied between 0.1 and 16.5% (mean = 6.2%; median = 5.2%; n = 40). Log10 EGFR was significantly and positively correlated with patient age. LI was significantly different according to tumor histology. Univariate Cox analysis (end point was cancer death) showed that age (P = 0.027), log10 EGFR (P = 0.025), and LI (P = 0.0019) were significant continuous variables, the survival being shortened when the covariable increased; tumor resection (P = 0.015, relative risk = 0.45) and histology (P = 0.0009) were significant categorical factors. A multivariate Cox analysis (forward selection) including age, histology, tumor resection, log10 EGFR, and LI revealed that log10 EGFR, LI, and tumor resection were the only independent significant predictors of survival. This multivariate approach reveals that the clinical prognostic factors of glial tumors, namely age and tumor histology, disappear, to the benefit of intrinsic characteristics of the tumor, i.e., EGFR expression and LI, suggesting that coupled EGFR and LI determination could be a useful tool for better evaluation of glial tumor outcome.
Syringomyelia is a rare, mainly sporadic disease of the spinal cord, which is associated with 80% of cases in which a Chiari Type I malformation is also present. A mendelian transmission of ...syringomyelia (autosomal dominant or recessive) has been proposed in approximately 2% of reported cases. The association of syringomyelia with hereditary diseases (Noonan's syndrome, phacomatoses) has been mentioned frequently in the literature. The authors report the presence of a Chiari Type I malformation accompanied by syringomyelia in two unrelated patients affected by a familial Type II blepharophimosis-ptosis-epicanthus inversus syndrome (BPES). The first patient was a 35-year-old woman who presented with a right C-8 root paresia. The second case involved a 20-year-old man who complained of cervical radicular pain. Both belong to families in which BPES was segregated in an autosomal dominant modality, but other family members had no known neurological symptoms. To the authors' knowledge, such a combination has never been described. Perhaps the possible involvement of a genetic component in some cases of Chiari Type I-associated syringomyelia will someday be debated.
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