311 research outputs found
Substituting model based indicators in Harvest Control Rules by observations using fuzzy logic methodology
The accepted manuscript (AM) is the final draft author manuscript, as accepted for publication by a journal, including modifications based on referees’ suggestions, before it has undergone copyediting, typesetting and proof correction. This is sometimes referred to as the post-print version. Source at: http://doi.org/10.1093/icesjms/fsx227Harvest Control Rules are predefined heuristic decision rules to provide quota advices for managed fisheries. Frequently statistical methods and biological assumptions expressed in mathematical models, are used to provide the Harvest Control Rules with initial information (indicators values). The aim of this article is to investigate a possible way forward of replacing these inputs by quantities of measurable observations, e.g. catch-at-age statistics. The article presents a method by which recruitment indexes and stock biomass indicators are obtained by non-parametric use of annual catch-at-age records, without filtering the raw data (observations) through mathematical models. Two related methods, applied on three empirical cases, are provided: First, showing that recruitment strengths of the Northeast Arctic cod, haddock, and saithe stocks, obtained by fuzzy logic methodology, are satisfactory captures by the use of catch-at-age data. Second, stock size indicators are estimated for the three species by the same catch-at-age data. The second task turns out to be more challenging than the first, but also in the case of stock size evaluation, the suggested procedure provides reasonable results when compared to standard stock assessment method
HARVEST FUNCTIONS: THE NORWEGIAN BOTTOM TRAWL COD FISHERIES
A detailed and comprehensive set of catch and effort data for the cod fisheries of 18 Norwegian bottom trawlers have been obtained for the period 1971–85, a period with few binding quota restrictions on vessel operations. Harvest functions have been designed and estimated. The independent variables are hours of trawling per vessel day and biomass of the cod stock (3+). Daily biomass estimates have been calculated by polynomial interpolation of the annual estimates of the International Council for the Exploration of the Sea (ICES). By maximizing the log-likelihood function using numerical methods, parameter estimates and performance indicators of the different models were obtained. The best result was obtained for a harvest model allowing for seasonal changes and with an autocorrelated error term. For this model, the stock-output elasticity is estimated at 0.424, the effort-output elasticity at 1.232, and the technological change at about a 2% annual increase in productivity. The seasonal changes in catchability are significant, with the lowest intra-annual catchability being less than 30% of the annual maximum.Resource /Energy Economics and Policy,
Disability and Poverty
This book is about being disabled and being poor and the social, cultural and political processes that link these two aspects of living in what has been characterised as a “vicious circle” (Yeo & Moore 2003). It is also about the strengths that people show when living with disability and being poor. How they try to overcome their problems and making the best out of what little they have. This book will appeal to academics, postgraduates and policymakers in disability studies, development studies, poverty and social exclusion
Recommended from our members
On Cost Efficiency in the Barents Sea Cod Fisheries
The theoretical economic performance of the year 2000 Norwegian fishing fleet in the Barents Sea cod fisheries are studied under different stock biomass levels and age compositions by applying the EconMult fleet model. Quarterly stock conditions during the period 1946-2004 have been investigated as this represent stock conditions which may naturally occur. Cost profiles and prices are from Norwegian official statistics of year 2000, while the harvest production equations are from the EconSimp2000 model. The study confirms a close relationship between relative economic performance between fleet segments and the stock properties. No dominant factor is found, as both stock properties, stock-output elasticities and fleet cost compositions are all important factors influencing the final result. Stock size and age composition in stock are however important factors, particularly the latter. The study indicates that bottom trawl may be relatively more efficient the second half of each year when the cod availability is reduced, while gill netters and long liners dominate the first half; except in years of extreme biomasses, as these often are characterised by large biomasses of young cod which suits the trawler fleet better than the conventional fleet
Recommended from our members
An Integrated Study of Possible Economic Effects of Global Warming on the Barents Sea Cod Fisheries
A number of simulations have been carried out to study different management scenarios in the Barents Sea cod fisheries when implementing physical and biological effects of global warming. A regional representation of the IPCC SPRES B2 scenario (world region OECD90) has been obtained through the REMO5.1 model. Water temperatures and plankton biomasses are calculated by the SinMod model, employing the REMO5.1 results. This study therefore represents a fully integrated model project, linking the global circulation model to the Barents Sea fisheries through regional downscaling for the investigated area. The presence of significant dynamic systems represents a major difficulty in isolating the global warming effects from the natural variations on all levels. One natural fluctuating factor, namely the occasional inflow of herring into the Barents Sea, is represented stochastically, while the effects of choice of management regimes are studied by selecting six possible management scenarios. The study seems however to support earlier study, claiming that the choice of management regimes potentially will have a greater impact on the biological and economic performance of the Barents Sea system when assuming the system to preserve its basic composition. Significant shifts in ecosystem structure as in the case of a high degree of alien species are not considered
Space – det 5. operasjonsdomenet: En styrkemultiplikator for Hærens kampkraft?
I 2019 ble Space erklært som et nytt militært operasjonsdomene i NATO. Samme år godkjente Forsvarssjef (FSJ) admiral Haakon Bruun-Hanssen operasjonalisering av romdomenet i Forsvaret. Forarbeidet til dette startet allerede med FSJ anbefaling i FMR 2015. Anbefalingen gikk ut på å øke bruken av satellitter i nordområdene og etablere Program Space i Forsvarsdepartementet. Program Space sin hovedoppgave var å utarbeide en plan for koordinert ledelse av Forsvarets romvirksomhet. (Fauske & Strand, 2022, s. 17). I 2020 ble Program Space flyttet til Forsvarsstaben (FST), og Forsvarets romvirksomhet var da en realitet.
Hæren bruker daglig rombasert teknologi, og kampplattformene har blitt mer høyteknologiske og avhengige av romdomenet for å fungere optimalt. Teknologiutviklingen akselererer i et forrykende tempo og informasjonstilfanget fra rombaserte tjenester er enormt. Derimot har ikke Hæren enda helt klart å forstå mulighetene og begrensningene det nye domenet gir. Spesielt ikke hva bortfall av teknologien vil gjøre med stridsfeltet og manøveren i operasjonen. Derfor har jeg i denne oppgaven valgt å ta for meg hvordan Hæren kan implementere og utnytte rombasert teknologi for å styrke kampkraften.
Gjennom undersøkelsen har jeg ikke kommet over annen forskning som omhandler Hærens relasjon til romdomenet. De 12 intervjuobjektene var derfor helt essensielle for å få en solid bredde på empirien. I prosessen med bearbeidelsen av innsamlet empiri, var det spesielt fire faktorer som krystalliserte seg som meget avgjørende for Hæren i møte med romdomenet og styrking av egen kampkraft. Disse faktorene er lederstøtte, beslutningstaking, samvirke og konsekvenser ved bortfall og kompetanse. Sistnevnte faktor viser seg å være kjernen i arbeidet med problemstillingen og de fem forskningsspørsmålene. Det er et stort kompetansegap i Hæren, og det kan med bakgrunn i oppgavens funn hevdes at det er tidskritisk å få tettet disse hullene.
Hæren er både positiv til, og motivert for et tettere samarbeid med Forsvarets romvirksomhet. Det er en felles enighet om at implementering og utnyttelse av romdomenet vil gi fordeler på stridsfeltet. Å ha tilgang til et tilnærmet kontinuerlig oppdatert situasjonsbilde vil spare tid i beslutningssløyfen, og gi en styrket fordel i favør av fienden. Trekantsamarbeidet mellom Forsvaret, Forsvarets forskningsinstitutt og sivil industri øker innovasjonstempoet, og gir organisasjonen tilganger til både nasjonale og allierte evner. Vår geostrategiske plassering og innovative utvikling innenfor romdomenet gjør oss til en viktig alliert i NATO. Undersøkelsens empiri gir et overordnet og tydelig signal om at det 5. operasjonsdomenet, Space, er en styrkemultiplikator for Hærens kampkraft
Measuring Disability and Inclusion in relation to the 2030 Agenda on Sustainable Development
publishedVersio
Recommended from our members
When, Where and What to Fish? Fishermen's Behaviour When Choosing Optional Seasonal Profiles
Most fishermen are faced with several options in both long and short term planning of their activity. In this paper we study fishers short term decisions when different seasonal fishery options are available. This involves choices of spatial and temporal allocation of effort as well as use of varying fishing gears in order to obtain the planned target specie mix. In a heterogeneous fishing fleet the seasonal options may differ considerably from vessel to vessel, also depending on its home port. The paper presents a framework wherein the seasonal choices are understood on the basis of economically rational behaviour where expected marginal benefit of the different options are evaluated and the most profitable season chosen. A monthly model is developed to describe the marginal profitability of the various fishing opportunities based on Norwegian data. The impact management decisions may have on the chosen seasonal profile and the vessel profitability is then discussed on the basis of the presented seasonal model. In particular we study the impacts of different quota allocation regimes. A diverse fleet structure may be an efficient response on highly fluctuating and unpredictable fish resources, while fisheries regulations may have the effect of reducing the flexibility by which the fleet can respond to such changes
Using prospective methods to identify fieldwork locations favourable to understand divergences in health care accessibility
Central to this article is the issue of choosing sites for where a fieldwork could provide a better understanding of divergences in health care accessibility. Access to health care is critical to good health, but inhabitants may experience barriers to health care limiting their ability to obtain the care they need. Most inhabitants of low-income countries need to walk long distances along meandering paths to get to health care services. Individuals in Malawi responded to a survey with a battery of questions on perceived difficulties in accessing health care services. Using both vertical and horizontal impedance, we modelled walking time between household locations for the individuals in our sample and the health care centres they were using. The digital elevation model and Tobler’s hiking function were used to represent vertical impedance, while OpenStreetMap integrated with land cover map were used to represent horizontal impedance. Combining measures of walking time and perceived accessibility in Malawi, we used spatial statistics and found spatial clusters with substantial discrepancies in health care accessibility, which represented fieldwork locations favourable for providing a better understanding of barriers to health access.publishedVersio
- …