scholarly journals Trends of white grouper landings in the Northeastern Mediterranean: reliability and potential use for monitoring

2020 ◽  
Vol 21 (1) ◽  
pp. 183
Author(s):  
SINAN MAVRUK
Keyword(s):  
Time Series ◽  
Age Groups ◽  
Monitoring Program ◽  
Bottom Trawl ◽  
Data Sets ◽  
Trawl Survey ◽  
Catch Per Unit Effort ◽  
Multiple Sources ◽  
Statistical Institute ◽  
The Status

As a consequence of national fishery statistics showing a sharp decline in the landings of white groupers (WG), Epinephelus aeneus (Geoffroy Saint-Hilaire, 1817) after 2010, the decision to ban any further fishing of the species was implemented by the Turkish management authority in 2016. Stakeholders have since strongly objected to this decision claiming that the trends of landing statistics are unreliable. Here, this assertion is questioned using multiple sources of data. The catch per unit effort (CPUE) from the fishery independent bottom trawl survey (2004-2018) officially reported landing statistics (2002-2017) and the microdata set of landings (2012-2016) gathered by the Turkish Statistical Institute (TUIK). Based on the results of this study, there was a clear parallelism amongst the data sets. Landing records and the CPUE time series revealed unimodal non-linear patterns along the time (p<0.001). Landings increased until 2010 and decreased thereon after, whereas CPUE values started to decrease after 2009. In segmented time series, there were no statistically significant differences between the direction and magnitude of slopes of landings and fishery independent data. Cross-correlations between landings and CPUE were statistically significant with one and two-year lag distances. This was because the earlier age groups were sampled with coastal bottom trawl operations. Combined with further efforts, this finding may help to develop a monitoring program for the status of white grouper populations in the northeastern Mediterranean and contribute to a better management strategy.

scholarly journals Influence of improved performance monitoring on the consistency of a bottom trawl survey

2003 ◽  
Vol 60 (4) ◽  
pp. 818-826 ◽  
Author(s):  
Mark Zimmermann ◽  
Mark E Wilkins ◽  
Kenneth L Weinberg ◽  
Robert R Lauth ◽  
Franklin R Shaw
Keyword(s):  
Time Series ◽  
Performance Monitoring ◽  
Bottom Trawl ◽  
Data Sets ◽  
Trawl Survey ◽  
Performance Measurements ◽  
Bottom Contact ◽  
Technological Advances ◽  
Improved Performance ◽  
Trawl Surveys

Abstract Numerous trawl hauls, made during the triennial bottom trawl surveys (1977–1998) conducted by the National Marine Fisheries Service off the U.S. West Coast, had unusually small catch rates of benthic fish and invertebrates (cpueB), probably because the trawl failed to contact the seabed (off-bottom). Technological advances in the equipment used to monitor trawl performance since 1986 have increased our ability to recognize off-bottom tows, and cpueB has risen. As direct trawl performance measurements were not available in earlier surveys, a minimum cpueB derived from the survey with the best monitoring of bottom contact of the time-series (1998) was used as a criterion to eliminate trawls with poor bottom contact from earlier surveys. The truncated data sets produce significantly larger biomass indices, especially in 1980, with increases of 43, 45, and 56% for Dover sole, petrale sole, and Pacific sanddab, respectively. The analysis suggests that changes in cpueB over the time-series may be related more to changing survey fishing methods than to changes in abundance. Other bottom trawl surveys, which have also added trawl monitoring equipment during their time-series, may have experienced similar changes in trawl performance.

scholarly journals Correcting density-dependent effects in abundance estimates from bottom-trawl surveys

2014 ◽  
Vol 71 (5) ◽  
pp. 1107-1116 ◽  
Author(s):  
Stan Kotwicki ◽  
James N. Ianelli ◽  
André E. Punt
Keyword(s):  
Stock Assessment ◽  
Dead Zone ◽  
Walleye Pollock ◽  
Assessment Model ◽  
Bottom Trawl ◽  
Trawl Survey ◽  
Negative Consequences ◽  
Catch Per Unit Effort ◽  
Density Dependent ◽  
Index Of Abundance

Abstract Indices of abundance are important for estimating population trends in stock assessment and ideally should be based on fishery-independent surveys to avoid problems associated with the hyperstability of the commercial catch per unit effort (cpue) data. However, recent studies indicate that the efficiency of the survey bottom trawl (BT) for some species can be density-dependent, which could affect the reliability of survey-derived indices of abundance. A function qe∼f(u), where qe is the BT efficiency and u the catch rate, was derived using experimentally derived acoustic dead-zone correction and BT efficiency parameters obtained from combining a subset of BT catch data with synchronously collected acoustic data from walleye pollock (Theragra chalcogramma) in the eastern Bering Sea (EBS). We found that qe decreased with increasing BT catches resulting in hyperstability of the index of abundance derived from BT survey. Density-dependent qe resulted in spatially and temporarily variable bias in survey cpue and biased population age structure derived from survey data. We used the relationship qe∼f(u) to correct the EBS trawl survey index of abundance for density-dependence. We also obtained a variance–covariance matrix for a new index that accounted for sampling variability and the uncertainty associated with the qe. We found that incorporating estimates of the new index of abundance changed outputs from the walleye pollock stock assessment model. Although changes were minor, we advocate incorporating estimates of density-dependent qe into the walleye pollock stock assessment as a precautionary measure that should be undertaken to avoid negative consequences of the density-dependent qe.

scholarly journals Cytokine storm in severe patient COVID-19 and curative plasmapheresis

2021 ◽  
Vol 64 (3) ◽  
pp. 32-35
Author(s):  
Victoria Rusu ◽  
Keyword(s):  
Intensive Care ◽  
Age Groups ◽  
Data Sets ◽  
Cytokine Storm ◽  
Reactive Protein ◽  
Immunological Markers ◽  
The Status ◽  
General Data ◽  
The Impact ◽  
Severe Patient

Background: In the intensive care unit, the curative plasmapheresis technique is widely applied among severe patients, who show signs of both endogenous and exogenous intoxication. The impact of isovolemic isooncotic curative plasmapheresis on the status of hemoleukogram and immunological markers has not been studied yet. Material and methods: The study is retrospective, observational. The medical records of 34 COVID-19 patients from the COVID intensive care units of Timofei Mosneaga Republican Clinical Hospital who benefited from isovolemic, curative isooncotic plasmapheresis were analyzed. There were 25 complete, analyzed data sets. General data were recorded: preplasmapheresis, postplasmaphesis hemoleukogram. Results: Isovolemic, isooncotic plasmapheresis, performed in patients with severe COVID-19, SARS-CoV2 showed effects of improving the status of laboratory indices that denote the evolution and favorable prognosis of the disease. The activity of the cytokine storm decreased in both groups of patients, both in those with a mean age of up to 60 years and in those over 60 years of age, with p = 0.001. Patients over 60 years of age had a marked improvement in serum ferritin index, compared to patients in the age group up to 60 years, in the period after plasmapheresis, p = 0.043. Analogously, the level of C-reactive protein was analyzed, which clearly decreases in patients <60 years of age, compared to those> 60 years of age, p = 0.037 Conclusions: Isovolemic, isooncotic plasmapheresis is a procedure performed in severe COVID-19 (SARS-CoV-2) patients to improve the status of the cytokine storm. Moreover, the performance of the procedure in different age groups induced an improvement in the satiety of hemoleukogram and proinflammatory indices.

Temporal and Spatial Consistency

2010 ◽  
pp. 89-110 ◽  
Author(s):  
Oliver Duke-Williams ◽  
John Stillwell
Keyword(s):  
Time Series ◽  
Age Groups ◽  
Register Data ◽  
Data Sets ◽  
Interaction Data ◽  
Patient Register ◽  
Health Authorities ◽  
Spatial Consistency ◽  
Using Data ◽  
Over Time

One of the major problems challenging time series research based on stock and flow data is the inconsistency that occurs over time due to changes in variable definition, data classification and spatial boundary configuration. The census of population is a prime example of a source whose data are fraught with these problems, resulting in even the simplest comparison between the 2001 Census and its predecessor in 1991 being difficult. The first part of this chapter introduces the subject of inconsistencies between related data sets, with general reference to census interaction data. Various types of inconsistency are described. A number of approaches to dealing with inconsistency are then outlined, with examples of how these have been used in practice. The handling of journey to work data of persons who work from home is then used as an illustrative example of the problems posed by inconsistencies in base populations. Home-workers have been treated in different ways in successive UK censuses, a factor which can cause difficulties not only for researchers interested in such working practices, but also for those interested in other aspects of commuting. The latter set of problems are perhaps more pernicious, as users are less likely to be aware of the biases introduced into data sets that are being compared. In the second half of this chapter, we make use of a time series data set of migration interaction data that does have temporal consistency to explore how migration propensities and patterns in England and Wales have changed since 1999 and in particular since the year prior to the 2001 Census. The data used are those that are produced by the Office of National Statistics based on comparisons of NHS patient records from one year to the next and adjusted using data on NHS patients re-registering in different health authorities. The analysis of these data suggests that the massive exodus of individuals from major metropolitan across the country that has been identified in previous studies is continuing apace, particularly from London whose net losses doubled in absolute terms between 1999 and 2004 before reducing marginally in 2005 and 2006. Whilst this pattern of counterurbanisation is evident for all-age flows, it conceals significant variations for certain age groups, not least those aged between 16 and 24, whose migration propensities are high and whose net redistribution is closely connected with the location of universities. The time series analyses are preceded by a comparison of patient register data with corresponding data from the 2001 Census. This suggests strong correlation between the indicators selected and strengthens the argument that patient register data in more recent years provide reliable evidence for researchers and policy makers on how propensities and patterns change over time.

Temporal and Spatial Consistency

2013 ◽  
pp. 1675-1696
Author(s):  
Oliver Duke-Williams ◽  
John Stillwell
Keyword(s):  
Time Series ◽  
Age Groups ◽  
Register Data ◽  
Data Sets ◽  
Interaction Data ◽  
Patient Register ◽  
Health Authorities ◽  
Spatial Consistency ◽  
Using Data ◽  
Over Time

One of the major problems challenging time series research based on stock and flow data is the inconsistency that occurs over time due to changes in variable definition, data classification and spatial boundary configuration. The census of population is a prime example of a source whose data are fraught with these problems, resulting in even the simplest comparison between the 2001 Census and its predecessor in 1991 being difficult. The first part of this chapter introduces the subject of inconsistencies between related data sets, with general reference to census interaction data. Various types of inconsistency are described. A number of approaches to dealing with inconsistency are then outlined, with examples of how these have been used in practice. The handling of journey to work data of persons who work from home is then used as an illustrative example of the problems posed by inconsistencies in base populations. Home-workers have been treated in different ways in successive UK censuses, a factor which can cause difficulties not only for researchers interested in such working practices, but also for those interested in other aspects of commuting. The latter set of problems are perhaps more pernicious, as users are less likely to be aware of the biases introduced into data sets that are being compared. In the second half of this chapter, we make use of a time series data set of migration interaction data that does have temporal consistency to explore how migration propensities and patterns in England and Wales have changed since 1999 and in particular since the year prior to the 2001 Census. The data used are those that are produced by the Office of National Statistics based on comparisons of NHS patient records from one year to the next and adjusted using data on NHS patients re-registering in different health authorities. The analysis of these data suggests that the massive exodus of individuals from major metropolitan across the country that has been identified in previous studies is continuing apace, particularly from London whose net losses doubled in absolute terms between 1999 and 2004 before reducing marginally in 2005 and 2006. Whilst this pattern of counterurbanisation is evident for all-age flows, it conceals significant variations for certain age groups, not least those aged between 16 and 24, whose migration propensities are high and whose net redistribution is closely connected with the location of universities. The time series analyses are preceded by a comparison of patient register data with corresponding data from the 2001 Census. This suggests strong correlation between the indicators selected and strengthens the argument that patient register data in more recent years provide reliable evidence for researchers and policy makers on how propensities and patterns change over time.

scholarly journals An application of two techniques for the analysis of short, multivariate non-stationary time-series of Mauritanian trawl survey data

2005 ◽  
Vol 62 (3) ◽  
pp. 353-359 ◽  
Author(s):  
Karim Erzini ◽  
Cheikh A. O. Inejih ◽  
Kim A. Stobberup
Keyword(s):  
Time Series ◽  
Factor Analysis ◽  
Fishing Effort ◽  
Stationary Time Series ◽  
Dynamic Factor ◽  
Data Sets ◽  
Trawl Survey ◽  
Explanatory Variables ◽  
Nao Index ◽  
Complementary Techniques

Abstract Min/max autocorrelation factor analysis (MAFA) and dynamic factor analysis (DFA) are complementary techniques for analysing short (>15–25 y), non-stationary, multivariate data sets. We illustrate the two techniques using catch rate (cpue) time-series (1982–2001) for 17 species caught during trawl surveys off Mauritania, with the NAO index, an upwelling index, sea surface temperature, and an index of fishing effort as explanatory variables. Both techniques gave coherent results, the most important common trend being a decrease in cpue during the latter half of the time-series, and the next important being an increase during the first half. A DFA model with SST and UPW as explanatory variables and two common trends gave good fits to most of the cpue time-series.

ICCAT stock assessments of Atlantic billfish

2003 ◽  
Vol 54 (4) ◽  
pp. 361 ◽  
Author(s):  
Victor Restrepo ◽  
Eric D. Prince ◽  
Gerry P. Scott ◽  
Yuji Uozumi
Keyword(s):  
Fishing Effort ◽  
Data Sets ◽  
Historical Overview ◽  
Catch Per Unit Effort ◽  
Historical Trends ◽  
Istiophorus Platypterus ◽  
Catch Data ◽  
Makaira Nigricans ◽  
Stock Assessments ◽  
The Status

This paper presents a historical overview of the assessments of the Atlantic stocks of blue marlin (Makaira nigricans), white marlin (Tetrapturus albidus) and sailfish (Istiophorus platypterus) that have been conducted by the International Commission for the Conservation of Atlantic Tunas between 1977 and 2000. Details are presented on the data sets used and the models applied, noting the strengths and weaknesses of the assessments. The major causes of uncertainty in the current perception of the status of the stocks are related to some of the data used and to their interpretation, especially historical trends in catch per unit effort. In particular, there are uncertainties about historical catch data, including discards, and about the degree to which longline fishing effort overlaps with billfish habitat. The paper concludes with an account of the efforts that should be made to reduce these uncertainties.

Longer-term effects of corrective input: an experimental approach

1998 ◽  
Vol 25 (3) ◽  
pp. 701-721 ◽  
Author(s):  
MATTHEW SAXTON ◽  
BELA KULCSAR ◽  
GREER MARSHALL ◽  
MANDEEP RUPRA
Keyword(s):  
Time Series ◽  
Experimental Approach ◽  
Data Sets ◽  
Negative Evidence ◽  
Verb Forms ◽  
Grammatical Errors ◽  
The Status ◽  
Within Subjects ◽  
Time Series Analyses ◽  
Positive Input

There is growing evidence that corrective input for grammatical errors is widely available to children (Farrar, 1992; Morgan, Bonamo & Travis, 1995). However, controversy still exists concerning the extent to which children can identify and exploit available negative input. In particular, very little is yet known about the longer-term effects of negative input. Performing a time series analysis on observational data, Morgan et al. (1995) conclude that corrective recasts are not related to future improvements in grammaticality. It is argued here, though, that the data sets analysed in this study are inherently ill-suited to the demands of time series analyses. The present study adopts an experimental approach in order to compare the effects of negative evidence versus positive input on the acquisition of irregular past tense verb forms. Twenty-six children (mean age 3;10) participated in a within-subjects design over a period of five weeks. It was found that improvements in the grammaticality of child speech were considerably greater in cases where negative evidence had been provided. Moreover, children's intuitions concerning the status of irregular and overregularized forms more closely approximated adult intuitions when corrective input was available.

scholarly journals A HARMONIZED DATASET ON GLOBAL EDUCATIONAL ATTAINMENT BETWEEN 1970 AND 2060 – AN ANALYTICAL WINDOW INTO RECENT TRENDS AND FUTURE PROSPECTS IN HUMAN CAPITAL DEVELOPMENT

2016 ◽  
Vol 82 (3) ◽  
pp. 315-363 ◽  
Author(s):  
Anne Goujon ◽  
Samir K.C. ◽  
Markus Speringer ◽  
Bilal Barakat ◽  
Michaela Potancoková ◽  
...  
Keyword(s):  
Time Series ◽  
Human Capital ◽  
Educational Attainment ◽  
Educational Development ◽  
Age Groups ◽  
Data Sets ◽  
Future Prospects ◽  
Human Capital Development ◽  
Recent Trends ◽  
Capital Development

Abstract:We hereby present a dataset produced at the Wittgenstein Centre (WIC) containing comprehensive time series on educational attainment and mean years of schooling (MYS). The dataset is split by 5-year age groups and sex for 171 countries and covers the period between 1970 and 2010. It also contains projections of educational attainment to 2060 based on several scenarios of demographic and educational development. The dataset is constructed around collected and harmonized empirical census and survey data sets for the projection base year. The paper presents the principles and methodology associated with the reconstruction and the projection, and how it differs from several previous exercises. It also proposes a closer look at the diffusion of education in world regions and how the existing gaps in terms of generation, gender, and geography have been evolving in the last 40 years.

Sign in / Sign up

Export Citation Format

Share Document