scholarly journals Extracting groundfish survey indices from the Ocean Biogeographic Information System (OBIS): an example from Fisheries and Oceans Canada

2009 ◽  
Vol 67 (4) ◽  
pp. 638-645 ◽  
Author(s):  
Daniel Ricard ◽  
Robert M. Branton ◽  
Donald W. Clark ◽  
Peter Hurley
Keyword(s):  
Time Series ◽  
Information System ◽  
Trawl Survey ◽  
Independent Information ◽  
Stock Assessments ◽  
The World ◽  
Abundance Trends ◽  
Selected Subset ◽  
Temporal Abundance ◽  
Trawl Surveys

Abstract Ricard, D., Branton, R. M., Clark, D. W., and Hurley, P. 2010. Extracting groundfish survey indices from the Ocean Biogeographic Information System (OBIS): an example from Fisheries and Oceans Canada. – ICES Journal of Marine Science, 67: 638–645. Scientific trawl surveys have been conducted in different regions of the world and by a variety of countries and agencies since the mid-1900s. Although the data are collected in a scientifically and statistically appropriate context and represent an important source of fishery-independent information for agency-specific stock assessments, their use and dissemination has often been limited to the agencies conducting the surveys. In recent years, Internet data portals such as the Ocean Biogeographic Information System have provided an arena for the wider distribution and use of marine fish data. Despite the increased accessibility of such data, their scientific acceptability has been limited by a lack of reproducibility in data analyses. We present a methodology for the computation of time-series of groundfish stock indices using publicly available trawl survey data derived from the Canadian Department of Fisheries and Oceans Maritimes region. Potential pitfalls associated with the computation of time-series are discussed and proper stratified random estimates of temporal abundance trends are compared with other methods for a selected subset of species. Also, the broader applicability of the methods for datasets collected under similar sampling designs is discussed, along with the reproducibility of the analyses and results.

scholarly journals Age-specific differences in the seasonal spatial distribution of butterfish (Peprilus triacanthus)

2016 ◽  
Vol 74 (1) ◽  
pp. 170-179 ◽  
Author(s):  
Charles F. Adams
Keyword(s):  
Time Series ◽  
Spatial Distribution ◽  
Reference Points ◽  
Trawl Survey ◽  
Spatial Equilibrium ◽  
Science Center ◽  
Fisheries Science ◽  
Specific Analysis ◽  
Stock Assessments ◽  
Seasonal Analysis

The spatial distribution of butterfish (Peprilus triacanthus) in the Northwest Atlantic Ocean was investigated using a suite of spatial indicators based on Northeast Fisheries Science Center spring and fall bottom trawl survey data, 1982–2013. In the spring, ages 2 and 3 were found farther northeast and deeper than age 1 butterfish, while in the fall, age 3 butterfish were found farther northeast and deeper than ages 0 and 1. There was no significant northward movement of butterfish in spring or fall over the course of either time-series. However, there was a significant increase in the area occupied by ages 1–3 in the spring that was correlated with surface temperature. This illustrates that responses to climate change may be manifested as range expansions, rather than poleward movement of the centre of gravity (i.e. bivariate weighted mean location of the population). Two changes were observed over the course of the fall time series, both for ages 1 and 2: increased spatial dispersion; and a decrease in depth. The former result would have been masked, while the latter would have been erroneously generalized to all age classes, if an age-specific analysis had not been done. This study demonstrates the importance of an age-based and seasonal analysis. It is also shown how a spatial distribution analyses can inform stock assessments by providing insights into diverging survey indices and availability to surveys in general. Similarly, spatial distribution analyses can be used to verify the spatial equilibrium assumption for the calculation of biological reference points.

scholarly journals Cumulated subsidence maps of Mexico city

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Penélope López Quiroz ◽  
Marie Pierre Doin ◽  
Iván Martínez Zazueta ◽  
Francisco Javier Osorno Covarrubias
Keyword(s):  
Time Series ◽  
Information System ◽  
Mexico City ◽  
Soil Compaction ◽  
Temporal Evolution ◽  
Synthetic Aperture ◽  
Radar Images ◽  
The World ◽  
Over Exploitation ◽  
Mexico Basin

A set of 38, 30 x 30 m resolution rasters of the subsidence over Mexico City and part of its metropolitan area, has been made available through this work. Subsidence rates in Mexico, one of the most populated cities in the world, reaches up to 0.4 m/yr, mainly due to soil compaction led by over exploitation of the Mexico Basin aquifer. To accurately map the spatial and temporal evolution of this phenomena, a set of Synthetic Aperture Radar images has been processed through interferometry and the results have been formatted as rasters that can be read and analyzed on any Geographic Information System. Moreover, the whole set of rasters can be visualized as interactive animated time series of the subsidence, through the journal platform.

scholarly journals Trends in Pacific Canadian groundfish stock status

2021 ◽  
Author(s):  
Sean C Anderson ◽  
Brendan M Connors ◽  
Philina A English ◽  
Robyn E Forrest ◽  
Rowan Haigh ◽  
...  
Keyword(s):  
Time Series ◽  
Credible Interval ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Pacific Cod ◽  
Strait Of Georgia ◽  
Individual Transferable Quotas ◽  
Stock Status ◽  
Stock Assessments ◽  
Trawl Surveys

We assembled estimated biomass (B) time series from stock assessments for 24 Pacific Canadian groundfish stocks and modelled average and stock status through 2020 based on biomass relative to each stock's (1) Limit Reference Point (B/LRP), (2) Upper Stock Reference (B/USR), and (3) biomass at maximum sustainable yield (B/BMSY). The overall mean B/LRP in 2020 was 3.2 (95% credible interval [CI]: 2.6-3.9). The overall mean B/USR and B/BMSY in 2020 was 1.5 (95% CI: 1.3-1.9) and 1.4 (95% CI: 1.1-1.7), respectively. Average stock status declined from 1950 to around 2000 and has remained relatively stable since then. The change around 2000 followed the implementation of ITQs (individual transferable quotas) for the trawl fleet and the commencement of the synoptic trawl surveys. As of their last assessment, four stocks (Strait of Georgia Lingcod [Area 4B], coastwide Bocaccio, and inside and outside Quillback Rockfish) had a greater than 5% probability of being below their LRP (i.e., in the "critical zone"); Pacific Cod in Area 3CD had a 4.6% probability. Roughly one-third of stocks had a greater than 1 in 4 chance of being below their USR (i.e., in the "cautious zone"). Conversely, two-thirds of assessed groundfish stocks had a high (>75%) probability of being above the USR (i.e., in the "healthy zone").

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.

Rose vs. Rho: a comparison of two approaches to address retrospective patterns in stock assessments

2020 ◽  
Author(s):  
Christopher M Legault
Keyword(s):  
Time Series ◽  
Single Model ◽  
Stock Status ◽  
Wide Range ◽  
Stock Assessments ◽  
Abundance Trends ◽  
Pros And Cons ◽  
The Difference ◽  
Parameter Values ◽  
The Rose

Abstract Two approaches to address retrospective patterns in stock assessments are compared. The Rose approach is an ensemble of models that all remove the retrospective pattern through changes in data, parameter values, or model assumptions. It is time intensive and can result in a wide range of historical abundance trends. The Rho approach modifies the terminal year estimates of a single model that exhibits a retrospective pattern. It is fast and easy to apply but results in a discontinuous time series. Neither approach identifies the source of the retrospective pattern. The pros and cons of these two approaches are compared in terms of catch advice and stock status using four examples with varying strength and direction of retrospective patterns. The choice of which approach to use could be based on time and expertise available to conduct and maintain an assessment, with Rose preferred if a lot of both are available while Rho preferred otherwise. If the Rho approach is used, managers should consider adjusting their control rule or risk buffer to account for the difference between Rose and Rho results shown here.

scholarly journals Business Days Time Series Weekly Trend and Seasonality

2021 ◽  
Vol 5 (1) ◽  
pp. 26
Author(s):  
Karlis Gutans
Keyword(s):  
Time Series ◽  
Global Warming ◽  
Exchange Rates ◽  
Temperature Data ◽  
Adjustment Method ◽  
Currency Exchange ◽  
Currency Exchange Rates ◽  
Time Series Decomposition ◽  
The World

The world changes at incredible speed. Global warming and enormous money printing are two examples, which do not affect every one of us equally. “Where and when to spend the vacation?”; “In what currency to store the money?” are just a few questions that might get asked more frequently. Knowledge gained from freely available temperature data and currency exchange rates can provide better advice. Classical time series decomposition discovers trend and seasonality patterns in data. I propose to visualize trend and seasonality data in one chart. Furthermore, I developed a calendar adjustment method to obtain weekly trend and seasonality data and display them in the chart.

scholarly journals Did the UN convention on the rights of the child reduce child mortality around the world? An interrupted time series analysis

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Christopher A. Tait ◽  
Abtin Parnia ◽  
Nishan Zewge-Abubaker ◽  
Wendy H. Wong ◽  
Heather Smith-Cannoy ◽  
...  
Keyword(s):  
Time Series ◽  
Time Series Analysis ◽  
Child Mortality ◽  
Interrupted Time Series ◽  
Interrupted Time Series Analysis ◽  
Series Analysis ◽  
Rights Of The Child ◽  
Reduce Child Mortality ◽  
The World

scholarly journals The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

1991 ◽  
Vol 37 (127) ◽  
pp. 388-400 ◽  
Author(s):  
Julian A. Dowdeswell ◽  
Gordon S. Hamilton ◽  
Jon Ove Hagen
Keyword(s):  
Time Series ◽  
North America ◽  
Active Phase ◽  
Aerial Photographs ◽  
Polar Ice ◽  
Phase Duration ◽  
Field Surveys ◽  
The World ◽  
Glacier Surges ◽  
Fast Motion

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

A comparison of global suicide terrorism by region before and after 9/11 terrorist attacks

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ahmet Guler ◽  
Mustafa Demir
Keyword(s):  
Time Series ◽  
Interrupted Time Series ◽  
Sub Saharan Africa ◽  
Terrorist Attacks ◽  
Suicide Terrorism ◽  
Content Type ◽  
The World ◽  
Before And After ◽  
Sub Saharan ◽  
Global Terrorism Database

Purpose This study aims to examine the effect of the 9/11 terrorist attacks on suicide terrorism in different regions of the world and changes in the trends in suicide terrorism according to regions before and after 9/11. Design/methodology/approach Using the data obtained from the Global Terrorism Database from 1981 to 2019, the descriptive statistics were computed first and then, independent samples t-tests were run to compare the monthly mean percentage of suicide-terrorism incidents that occurred in each region between the pre-9/11 and the post-9/11 periods. Finally, to statistically assess the effect of the 9/11 attacks and changes in the trends for the dependent variables over time, monthly interrupted time-series analyzes were conducted. Findings The results of monthly interrupted time series analyzes showed that after the 9/11 attacks, the trends for suicide-terrorism rates decreased significantly in three regions including South Asia, the Middle East and North Africa and Europe, while the trend for suicide-terrorism rates increased significantly in Sub-Saharan Africa. However, no statistically significant changes in the trends in suicide-terrorism rates occurred in three regions including North America, East Asia and Central Asia and Southeast Asia before 9/11, during November 2001 or after 9/11. Originality/value This study indicates the critical importance of the 9/11 terrorist attacks in suicide terrorism and its impact on these events in different regions of the world. The research also provides some recommendations concerning the effectiveness of defensive and offensive counterterrorism policies against suicide terrorism.

Assessment of E-Government Portals

2022 ◽  
Vol 14 (1) ◽  
pp. 0-0
Keyword(s):  
Information System ◽  
Public Service ◽  
Public Services ◽  
Government Information ◽  
Assessment Framework ◽  
Web Portals ◽  
Framework Model ◽  
The World ◽  
Government Portal ◽  
The Web

This research revealed the importance of public service web portals for an e-government information system. An e-government portal is interacting with its administrators, citizens, businesses and other governments helping them increase their operations performance. The authors have developed, modeled, formulated and compared an efficient assessment framework for e-government portals. In order to accomplish such task many quantitative factors and indicators were taken under consideration; also, other frameworks have been studied and compared. The authors focused on the web portals services quantity that the interested parties should use, in order to create an well designed public services’ web portal. This research provides a framework model to evaluate the basic common digital public services that a government offers to its interactive stakeholders, so that all other countries across the world can predefine weaknesses and strengths, improve existing or formulating new e-services. The importance of the assessment framework model is thoroughly explained through the results.

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