Developing empirical management procedures to meet management objectives for data-limited fisheries

Most of the world’s fish stocks are considered data-limited and there are insufficient data for complex stock assessment models; nevertheless, scientifically sound management advice is required. Empirical management procedures rely on empirical data and can guide management decisions. The main goals of this project were to develop and test empirical management procedures to improve data-limited fisheries management. Candidate management procedures can be evaluated using management strategy evaluation, which simulates the managed system and management in a feedback loop. Here, many generic operating models were generated covering a wide range of life histories. First, a trend-based empirical management procedure was explored. Simulations revealed that the management performance depended on the individual growth rate of the species, and the method delivered poor performance with high risk of stock depletion for faster-growing species. However, management performance could be improved by applying a genetic algorithm and optimisation towards specified management objectives such as long-term sustainable exploitation and risk limits demanded by stakeholders. An alternative empirical method (harvest rates) was found to be applicable to faster-growing species. Optimised parameterisations of the empirical methods from generic simulations were confirmed for several case study stocks with more available data. These analyses suggested that the generic methods lead to precautionary management, but management performance can be improved through case-specific optimisation. The outcomes of this project showed that the current management practices of data-limited fisheries resources applied by the International Council for the Exploration of the Sea in Europe are insufficient and do not ensure sustainable and precautionary exploitation, even though this is required through international treaties. However, the management procedures evaluated in this study show a way to overcome current management deficiencies and indicate that simple empirical management procedures are a scientifically sound alternative to expensive model-based management approaches.Open Acces

Full currency convertibility in Eastern Europe?

In the countries of Eastern Europe the question as to the degree of currency convertibility is among the most important decisions to be taken when setting the framework for a free market economy. This article attempts to indicate the monetary and fiscal measures that will be required if the reform countries willing and able to be integrated into the EC and OECD are to proceed rapidly to the liberalisation of capital transactions

Financial opening in developing countries

Many developing countries are currently considering liberalisation of external capital flows. While the ultimate objective of financial opening is to raise efficiency and growth, the reform process must be carefully designed to achieve these results. A recent conference has discussed the policy choices

Correlated motion of two atoms trapped in a single mode cavity field

We study the motion of two atoms trapped at distant positions in the field of a driven standing wave high-Q optical resonator. Even without any direct atom-atom interaction the atoms are coupled through their position dependent influence on the intracavity field. For sufficiently good trapping and low cavity losses the atomic motion becomes significantly correlated and the two particles oscillate in their wells preferentially with a 90 degrees relative phase shift. The onset of correlations seriously limits cavity cooling efficiency, raising the achievable temperature to the Doppler limit. The physical origin of the correlation can be traced back to a cavity mediated cross-friction, i.e. a friction force on one particle depending on the velocity of the second particle. Choosing appropriate operating conditions allows for engineering these long range correlations. In addition this cross-friction effect can provide a basis for sympathetic cooling of distant trapped clouds.Comment: 10 pages, 9 figures, accepted for publication in Phys. Rev. A. Minor grammatical changes to previous versio

An Exploration into the Determinants of Patent Activities. Some Empirical Evidence for Austria

Series: Discussion Papers of the Institute for Economic Geography and GIScienc

Hundert Jahre für den Naturschutz

HUNDERT JAHRE FÜR DEN NATURSCHUTZ Hundert Jahre für den Naturschutz / Fischer, Helmut (Rights reserved) ( -