scholarly journals Generic management procedures for data-poor fisheries: forecasting with few data

2014 ◽  
Vol 72 (1) ◽  
pp. 251-261 ◽  
Author(s):  
H. F. Geromont ◽  
D. S. Butterworth
Keyword(s):  
Scientific Management ◽  
Fish Stocks ◽  
Control Rules ◽  
Management Procedure ◽  
Key Characteristics ◽  
Management Procedures ◽  
Wide Range ◽  
Generic Management ◽  
Few Data ◽  
Index Of Abundance

Abstract The majority of fish stocks worldwide are not managed quantitatively as they lack sufficient data, particularly a direct index of abundance, on which to base an assessment. Often these stocks are relatively “low value”, which renders dedicated scientific management too costly, and a generic solution is therefore desirable. A management procedure (MP) approach is suggested where simple harvest control rules are simulation tested to check robustness to uncertainties. The aim of this analysis is to test some very simple “off-the-shelf” MPs that could be applied to groups of data-poor stocks which share similar key characteristics in terms of status and demographic parameters. For this initial investigation, a selection of empirical MPs is simulation tested over a wide range of operating models (OMs) representing resources of medium productivity classified as severely depleted, to ascertain how well these different MPs perform. While the data-moderate MPs (based on an index of abundance) perform somewhat better than the data-limited ones (which lack such input) as would be expected, the latter nevertheless perform surprisingly well across wide ranges of uncertainty. These simple MPs could well provide the basis to develop candidate MPs to manage data-limited stocks, ensuring if not optimal, at least relatively stable sustainable future catches.

scholarly journals Complex assessments or simple management procedures for efficient fisheries management: a comparative study

2014 ◽  
Vol 72 (1) ◽  
pp. 262-274 ◽  
Author(s):  
H. F. Geromont ◽  
D. S. Butterworth
Keyword(s):  
Fishery Management ◽  
Stock Assessment ◽  
Assessment Methods ◽  
Essential Requirement ◽  
Fish Stocks ◽  
Control Rules ◽  
Management Procedures ◽  
Simple Rules ◽  
Sound Management

Abstract Complex stock assessment methods are data- and expertise-hungry, with the annual updates of catch-at-age data and models typically seen as an essential requirement for sound management. But are the heavy commitments of resources required for this level of annual intervention really necessary to achieve efficient long-term fishery management? This question is addressed through a retrospective analysis of management performance over the last 20 years for four North Atlantic fish stocks. The assessments for two of these stocks have exhibited fairly strong retrospective patterns. The actual assessment advice for these stocks was provided based on complex assessment methods making use of age data. The outcomes are compared with what could have been achieved with much simpler catch control rules based upon age-aggregated survey indices alone. Even for the stocks whose assessments exhibit retrospective patterns, these simple rules can achieve virtually equivalent catch and risk performance, with much less interannual TAC variability, compared with what actually occurred over the past 20 years.

Using Bayesian decision analysis to help achieve a precautionary approach for managing developing fisheries

1998 ◽  
Vol 55 (12) ◽  
pp. 2642-2661 ◽  
Author(s):  
M K McAllister ◽  
G P Kirkwood
Keyword(s):  
Decision Analysis ◽  
Probability Distributions ◽  
Bayesian Decision ◽  
Catch Per Unit Effort ◽  
Precautionary Approach ◽  
Control Rules ◽  
Trade Offs ◽  
Management Procedures ◽  
Resource Data ◽  
Few Data

Bayesian decision analysis offers a useful framework for helping to achieve a precautionary approach to managing developing fisheries. With few data on the resource, data and experience from ecologically similar fish populations (or prior information) can also be used to quantitatively evaluate alternative procedures for managing the resource and to provide management advice. We applied Bayesian decision analysis to a hypothetical developing fishery in which a logistic model was fitted to catch per unit effort data. We evaluated the trade-offs in yield and the risk of depletion of catch and effort control rules. Effort control rules yielded average catches nearly 40% larger for levels of risk similar to those given by catch control rules. Management procedures designed to reduce the risks of implementing high harvest rates and to promote resource recovery at low stock sizes reduced the risks of overexploitation and caused only very small reductions in average catch. However, -50 and +100% biases in prior probability distributions for some parameters and the use of overly precise priors (CV < 0.5) in stock assessments caused large increases in the risk of overexploitation.

scholarly journals Consideration of uncertainties in environmental science and management with examples from Pacific salmon

2015 ◽  
Author(s):  
Randall Peterman
Keyword(s):  
Quantitative Methods ◽  
Environmental Science ◽  
Pacific Salmon ◽  
Natural Populations ◽  
Observation Error ◽  
Imperfect Data ◽  
State Dependent ◽  
Strategy Evaluation ◽  
Management Procedure ◽  
Management Procedures

An informal review of the history of new quantitative methods in environmental science, including environmental risk assessment, shows about a 10- to 20-year lag in wide acceptance of such methods by management agencies. To reduce that lag time as innovative methods continue to emerge, environmental scientists will need to work much more intensively with communications specialists on better ways to explain risk analyses and decision-making strategies to non-technical decision makers and the public. Four key uncertainties make such communication difficult: (1) natural variability in both physical and biological processes, (2) imperfect data arising from observation error (i.e., measurement error), (3) incomplete understanding of an environmental system's structure and dynamics, and (4) outcome uncertainty (deviations between realized outcomes and management targets). These uncertainties create risks -- risks to natural populations as well as to people who use them. Examples of these four sources of uncertainty are presented here for Pacific salmon (Oncorhynchus spp.). One promising framework for explicitly taking such uncertainties into account was initially developed in the early 1990s by scientific advisors to the International Whaling Commission. They built stochastic models, which essentially were comprehensive formal decision analyses, to derive management procedures (i.e., sampling designs for collecting data, methods to analyze those data, and state-dependent harvest-control rules for use by managers) that were robust to all the uncertainties considered. This method of "Management Strategy Evaluation" or "Management Procedure Evaluation" is now considered the "gold standard" for conducting risk assessments and making risk-management decisions in marine fisheries.

scholarly journals ESG disclosure patterns in the Baltics

2020 ◽  
Author(s):  
Ilze Zumente ◽  
Nataļja Lāce ◽  
Jūlija Bistrova
Keyword(s):  
Content Analysis ◽  
Statistical Analysis ◽  
Stock Exchange ◽  
Financial Disclosure ◽  
Social Dimensions ◽  
Key Characteristics ◽  
Wide Range ◽  
Financial Metrics ◽  
The Baltic ◽  
Disclosure Patterns

The goal of this article is to provide evidence on the volume of ESG disclosures of 34 companies listed on the NASDAQ Baltic stock exchange. It provides a broad view of the non-financial disclosure thoroughness and offers conclusions on the key characteristics of the Baltic listed companies in terms of ESG. By performing content analysis of the publicly available reports based on 106 ESG criteria and statistical analysis of the retrieved data, the disclosure patterns across reporting dimensions, industries, and company characteristics are analyzed. Authors find a wide range (8% to 67%) ESG transparency scores with an average of 41%. On aggregate, governance and social dimensions are reported better (49% and 44%) than environmental (24%). Correlation analysis was performed to test the correlation between ESG and selected financial metrics revealing that the ESG disclosure score correlates with the firm’s market capitalization.

scholarly journals Prosedur Pengelolaan Keuangan pada Dinas Pemuda, Olahraga, Kebudayaan dan Pariwisata Kabupaten Kapuas

2019 ◽  
Vol 3 (1) ◽  
pp. 1-11
Author(s):  
Vivi Pancasari Kusumawardani
Keyword(s):  
Financial Management ◽  
Youth Sports ◽  
Secondary Data ◽  
District Office ◽  
Sports Culture ◽  
Management Procedure ◽  
Analysis Technique ◽  
Management Procedures ◽  
Data Collection Technique ◽  
District Culture

This study aims to determine the procedure for managing financial statements at the Kapuas District Office of Youth, Sports, Culture and Tourism.The data used in this study are documentary data, while the data sources used are secondary data with data collection technique in the form of documentation technique, namely collecting written material in the form of data obtained from the Finance Department of the Department of Youth, Sports, Culture and Tourism Kapuas Year 2015 and 2016. Data analysis technique use qualitative analysis technique.The results showed that: (1) the Kapuas District Youth, Sports, Culture and Tourism Office had financial management procedures as a guideline governing the financial management process that covered all financial aspects managed by the Kapuas District Culture, Youth and Sports Service. (2) In the financial management procedure owned by the Department of Youth, Sports, Culture and Tourism of the Kapuas Regency, it has complied with government regulations stipulated in the Minister of Home Affairs Regulation Number 13 of 2006.

scholarly journals A Comparison between Two Sonic Measuring Systems for Demersal Fish

1970 ◽  
Vol 27 (4) ◽  
pp. 737-742 ◽  
Author(s):  
R. G. Dowd ◽  
E. Bakken ◽  
O. Nakken
Keyword(s):  
Linear Relation ◽  
Demersal Fish ◽  
High Density ◽  
Measuring Systems ◽  
Fish Stocks ◽  
Digital Counter ◽  
Schooling Fish ◽  
Wide Range ◽  
Two Systems

Two sonic methods for estimation of abundance of fish stocks, the echo integrator and the digital counter methods, were compared on single and schooling fish in the Lofoten area of Norway during March 1969. Good correlation was obtained between the two systems for both situations, but the slopes of the regressions of integrated values on the digital counter differed significantly between low and high density fish concentrations. This suggests that the two systems treated the echo information differently, but nevertheless maintained a linear relation between themselves over a wide range of counts.

scholarly journals Population variability under stressors is dependent on body mass growth and asymptotic body size

2020 ◽  
Vol 7 (2) ◽  
pp. 192011
Author(s):  
Leonie Färber ◽  
Rob van Gemert ◽  
Øystein Langangen ◽  
Joël M. Durant ◽  
Ken H. Andersen
Keyword(s):  
Body Mass ◽  
Life Histories ◽  
Random Noise ◽  
Fish Stock ◽  
Vital Rates ◽  
Anthropogenic Pressures ◽  
Fish Stocks ◽  
Asymptotic Size ◽  
Wide Range ◽  
Stock Recruitment

The recruitment and biomass of a fish stock are influenced by their environmental conditions and anthropogenic pressures such as fishing. The variability in the environment often translates into fluctuations in recruitment, which then propagate throughout the stock biomass. In order to manage fish stocks sustainably, it is necessary to understand their dynamics. Here, we systematically explore the dynamics and sensitivity of fish stock recruitment and biomass to environmental noise. Using an age-structured and trait-based model, we explore random noise (white noise) and autocorrelated noise (red noise) in combination with low to high levels of harvesting. We determine the vital rates of stocks covering a wide range of possible body mass (size) growth rates and asymptotic size parameter combinations. Our study indicates that the variability of stock recruitment and biomass are probably correlated with the stock's asymptotic size and growth rate. We find that fast-growing and large-sized fish stocks are likely to be less vulnerable to disturbances than slow-growing and small-sized fish stocks. We show how the natural variability in fish stocks is amplified by fishing, not just for one stock but for a broad range of fish life histories.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

scholarly journals Development of an assessment tool for infrastructure asset management of urban drainage systems

2020 ◽  
Author(s):  
Meriem Igroufa ◽  
Abbas Benzerra ◽  
Abdelghani Seghir
Keyword(s):  
Asset Management ◽  
Second Phase ◽  
Urban Drainage ◽  
Measurement Scales ◽  
Drainage Systems ◽  
Weighted Sum Method ◽  
Management Procedure ◽  
Management Procedures ◽  
Urban Drainage Systems ◽  
Infrastructure Asset Management

Abstract The present paper deals with the improvement of infrastructure asset management of urban drainage systems (UDS). A numerical tool for assessing the existing management procedures is proposed. It is based on a participatory methodology for the construction of a set of performance indicators. This methodology consists of two phases. The first concerns the identification of priority objectives, criteria and indicators related to the management of the UDS infrastructure. The second phase concerns the assessment of the global performance for each identified objective. Performance measurement scales are first defined for all the elements of the proposed methodology. Then, the Fuzzy Analytical Hierarchy Process (FAHP) is used for the weighting stage, and the Weighted Sum Method is used for the aggregation of indicators and criteria. To illustrate this methodology, a case study concerning Bejaia City in northern Algeria was carried out. Two priority objectives are identified for this case, they are divided into 6 criteria and 31 indicators. The results of the application of the developed tool highlighted some weaknesses that need improvements in the actual management procedure applied by the local sanitation services.

scholarly journals A quantitative taxonomic review of Fusichonetes and Tethyochonetes (Chonetidina, Brachiopoda)

2017 ◽  
Vol 91 (6) ◽  
pp. 1296-1305 ◽  
Author(s):  
Hui-ting Wu ◽  
G. R. Shi ◽  
Wei-hong He
Keyword(s):  
Cladistic Analysis ◽  
Species Classification ◽  
Triassic Boundary ◽  
Morphological Variations ◽  
Key Characteristics ◽  
Wide Range ◽  
Kolmogorov Smirnov ◽  
Morphological Variables ◽  
End Members ◽  
Permian Triassic Boundary

AbstractTwo middle Permian (Capitanian) to Early Triassic (Griesbachian) rugosochonetidae brachiopod genera, Fusichonetes Liao in Zhao et al., 1981 and Tethyochonetes Chen et al., 2000, have been regarded as two distinct taxa and used as such for a wide range of discussions including biostratigraphy, paleoecology, paleobiogeography, and the Permian-Triassic boundary mass extinction. However, the supposed morphological distinctions between the two taxa are subtle at best and appear to represent two end members of a continuum of morphological variations. In this study, we applied a range of quantitative and analytical procedures (bivariate plots, Kolmogorov-Smirnov test, categorical principle component analysis, and cladistic analysis) to a dataset of 15 quantified morphological variables, integrating both key external and internal characters, measured from 141 specimens of all well-known Fusichonetes and Tethyochonetes in order to test whether or not these two genera could be distinguished in view of the chosen characters. The results indicate that these two genera are morphologically indistinguishable and that the species classification previously applied to these two genera appears to represent polyphyletic groupings within the genus Fusichonetes. Consequently, Tethyochonetes is concluded to be a junior synonym of Fusichonetes. The diagnosis and key characteristics of Fusichonetes are clarified and refined based on a new suite of well-preserved specimens from the Permian−Triassic Xinmin section in South China.

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