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Migration Costs (migration + cost)
Selected AbstractsPopulation density of migratory and resident brown trout (Salmo trutta) in relation to altitude: evidence for a migration costJOURNAL OF ANIMAL ECOLOGY, Issue 1 2001T. Bohlin Abstract 1For anadromous salmonids, the positive relations found in previous studies between adult size/age and stream characteristics suggest that the migration cost increases with stream length, water discharge and the altitude of the spawning site. In this study we hypothesized that the altitude of the spawning site is positively related to the migration effort. 2Life-history theory predicts (i) that the equlibrium egg density, which is a fitness measure, thereby will decline more rapidly with altitude in migratory than in stream-resident populations, and therefore (ii) that residency will be selected for at large enough altitudes. 3As the density of juveniles is a function of egg density, we hypothesized that (a) altitude has stronger effect on juvenile density in migratory than in resident populations, and (b) juvenile density is larger in migratory than in resident populations. 4We tested (a) and (b) using multivariate methods for electrofishing data from 164 sea-migratory and 167 stream-resident populations of brown trout Salmotrutta L. in Sweden. Both predictions were supported; the juvenile density was larger and declined more rapidly with altitude in migratory than in resident populations. 5The results are further evidence that migration costs reduce fitness in anadromous salmonids. [source] Why is Employment Protection Stricter in Europe than in the United States?ECONOMICA, Issue 295 2007MICHÈLE BELOT I argue that the reason why the United States prefers a lower level of employment protection than the European countries lies in the differences in gains and costs from geographical mobility. I present a model in which labour migration and employment protection are both determined endogenously. The labour market is modelled within a matching framework, where the employment protection reduces both the job finding and job firing rates. Countries with low migration costs and high economic heterogeneity may prefer no employment protection so that workers can move quickly to better horizons rather than being maintained in low productive activities. [source] EU Enlargement, Migration, and Lessons from German UnificationGERMAN ECONOMIC REVIEW, Issue 3 2000Hans-Werner Sinn The paper studies the role of international implications after EU enlargement. Based on a formal model with migration costs for both capital and labor, it predicts a two-sided migration from the new to the old EU countries which is later reversed. As the migration pattern chosen by market forces turns out to be efficient, migration should not be artificially reduced by means of legal constraints or subsidies to the new member countries. The paper draws the parallel with German unification and points out the lessons to be learned by Europe. The analysis concludes with a brief discussion of the second-best problem posed by the existence of welfare states in the old member countries. [source] Population density of migratory and resident brown trout (Salmo trutta) in relation to altitude: evidence for a migration costJOURNAL OF ANIMAL ECOLOGY, Issue 1 2001T. Bohlin Abstract 1For anadromous salmonids, the positive relations found in previous studies between adult size/age and stream characteristics suggest that the migration cost increases with stream length, water discharge and the altitude of the spawning site. In this study we hypothesized that the altitude of the spawning site is positively related to the migration effort. 2Life-history theory predicts (i) that the equlibrium egg density, which is a fitness measure, thereby will decline more rapidly with altitude in migratory than in stream-resident populations, and therefore (ii) that residency will be selected for at large enough altitudes. 3As the density of juveniles is a function of egg density, we hypothesized that (a) altitude has stronger effect on juvenile density in migratory than in resident populations, and (b) juvenile density is larger in migratory than in resident populations. 4We tested (a) and (b) using multivariate methods for electrofishing data from 164 sea-migratory and 167 stream-resident populations of brown trout Salmotrutta L. in Sweden. Both predictions were supported; the juvenile density was larger and declined more rapidly with altitude in migratory than in resident populations. 5The results are further evidence that migration costs reduce fitness in anadromous salmonids. [source] | ||||||||||