The Inclusion of Stocks in Multi-species Fisheries: The Case of Danish Seiners

Efficiency analysis in fisheries has become an area of increased research. However, setting up models to perform such analyses is complicated and several important modeling issues, including choice of inputs and outputs, level of aggregation and inclusion of stock indices, have only briefly been addressed in the literature. The latter issue is addressed in this paper, using data on Danish seiners and Data Envelopment Analysis (DEA) to estimate efficiency. Production in fisheries is obviously dependent on the fish stocks, and comparing vessel efficiency, therefore, needs to account for stock developments. Three methods to include fish stocks are analyzed. It is shown that estimations based on the Catch Per Unit Effort (CPUE) stock measure differ from the estimations based on independent stock measures, and are independent of the choice of time horizon and choice of input/output measures.Data Envelopment Analysis, fish stock, multi-species fisheries, technical efficiency, Resource /Energy Economics and Policy, Q22,

Quota Trading and Profitability: Theoretical Models and Applications to Danish Fisheries

Using Data Envelopment Analysis (DEA), we provide a framework to analyze the potential gains from quota trading. We compare the industry profit and structure before and after a free trade reallocation of production quotas. The effects of tradable production quotas depend on several technological and behavioral characteristics, including the ability to learn best practice (catch-up) and the ability to change the input and output composition (mix). To illustrate the usefulness of our approach, we analyze a dataset from the Danish fishery. We study the industry profit and structure under each of four sets of technological and behavioral characteristics.Data Envelopment Analysis (DEA), Individual Transferable Quotas (ITQ), reallocation, technical efficiency, allocative efficiency, fishery, Agribusiness, C61, L51, Q22, Q28,

Dynamics of semifluxons in Nb long Josephson 0-pi junctions

We propose, implement and test experimentally long Josephson 0-pi junctions fabricated using conventional Nb-AlOx-Nb technology. We show that using a pair of current injectors, one can create an arbitrary discontinuity of the Josephson phase and in particular a pi-discontinuity, just like in d-wave/s-wave or in d-wave/d-wave junctions, and study fractional Josephson vortices which spontaneously appear. Moreover, using such junctions, we can investigate the \emph{dynamics} of the fractional vortices -- a domain which is not yet available for natural 0-pi-junctions due to their inherently high damping. We observe half-integer zero-field steps which appear on the current-voltage characteristics due to hopping of semifluxons.Comment: Fractional vortices in conventional superconductors ;-