839 research outputs found

    MANAGEMENT OF ARTISANAL FISHERIES: THE ROLE OF MARINE FISHERY RESERVES

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    Resource /Energy Economics and Policy,

    Are Fishermen Rational? A Fishing Expedition

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    Uncertainty is a defining characteristic of fisheries. Fishermen make decisions affecting their livelihood daily and even hourly, often with scant information on which to evaluate alternatives. Cognitive psychologists and behavioral economists have shown that decisions involving uncertainty often diverge substantially from what would be predicted by expected utility theory. I review relevant findings from the literature on decision making under uncertainty and previous empirical modeling of fishing decisions, and explore the implications of a number of different behavioral theories on fishing decisions of various types. Excerpts from ethnographic interviews of groundfish fishermen in New England are used to illustrate how these fishermen deal with uncertainty in decisions they make about when, where, how, and how long to fish. The interviews provide anecdotal evidence in support of prospect theory and other behavioral hypotheses that appear to contrast with what would be considered rational behavior from a neoclassical economics perspective.Fisheries, risk aversion, prospect theory, uncertainty, heuristics and biases., Community/Rural/Urban Development, Institutional and Behavioral Economics, Research Methods/ Statistical Methods, D01, Q22.,

    ON DIRECT AND INDIRECT MANAGEMENT OF FISHING CAPACITY

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    Resource /Energy Economics and Policy,

    MARINE RESERVES FOR FISHERIES MANAGEMENT

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    Conventional methods of regulating commercial fisheries restrict catch by limiting either the quantity or efficiency of fishing effort, or by putting direct limits on catch. These regulatory practices are neither feasible nor desirable for many fisheries, and have failed to conserve fishery stocks in other fisheries. Marine reserves may be an effective alternative management strategy for some fisheries. Here we develop a dynamic model of marine reserves applicable to inshore fisheries. In contrast to previous models of reserves, the model is fully dynamic and provides information on both equilibrium conditions and the path to equilibrium. A simulation model based on red snapper data from the Gulf of Mexico is presented. The simulation results suggest that marine reserves can sustain or increase yields for moderate to heavily fished fisheries but will probably not improve yields for lightly fished fisheries.Resource /Energy Economics and Policy,

    Geographic Proximity Not a Prerequisite for Invasion: Hawaii Not the Source of California Invasion by Light Brown Apple Moth (Epiphyas postvittana)

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    BACKGROUND: The light brown apple moth (LBAM), Epiphyas postvittana (Walker), is native to Australia but invaded England, New Zealand, and Hawaii more than 100 years ago. In temperate climates, LBAM can be a major agricultural pest. In 2006 LBAM was discovered in California, instigating eradication efforts and quarantine against Hawaiian agriculture, the assumption being that Hawaii was the source of the California infestation. Genetic relationships among populations in Hawaii, California, and New Zealand are crucial to understanding LBAM invasion dynamics across the Pacific. METHODOLOGY/PRINCIPAL FINDINGS: We sequenced mitochondrial DNA (mtDNA) from 1293 LBAM individuals from California (695), Hawaii (448), New Zealand (147), and Australia (3) to examine haplotype diversity and structure among introduced populations, and evaluate the null hypothesis that invasive populations are from a single panmictic source. However, invasive populations in California and New Zealand harbor deep genetic diversity, whereas Hawaii shows low level, shallow diversity. CONCLUSIONS/SIGNIFICANCE: LBAM recently has established itself in California, but was in Hawaii and New Zealand for hundreds of generations, yet California and New Zealand show similar levels of genetic diversity relative to Hawaii. Thus, there is no clear relationship between duration of invasion and genetic structure. Demographic statistics suggest rapid expansion occurring in California and past expansions in New Zealand; multiple introductions of diverse, genetically fragmented lineages could contribute to these patterns. Hawaii and California share no haplotypes, therefore, Hawaii is not the source of the California introduction. Paradoxically, Hawaii and California share multiple haplotypes with New Zealand. New Zealand may be the source for the California and Hawaii infestations, but the introductions were independent, and Hawaii was invaded only once. This has significant implications for quarantine, and suggests that probability of invasion is not directly related to geographic distance. Surprisingly, Hawaiian LBAM populations have much lower genetic diversity than California, despite being older

    Probing the cosmic star formation using long Gamma-Ray Bursts: New constraints from the Spitzer Space Telescope

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    We report on IRAC-4.5mic, IRAC-8.0mic and MIPS-24mic deep observations of 16 Gamma-Ray Burst (GRBs) host galaxies performed with the Spitzer Space Telescope, and we investigate in the thermal infrared the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with these objects. Our sample is derived from GRBs that were identified with sub-arcsec localization between 1997 and 2001, and only a very small fraction (~20%) of the targeted sources is detected down to f_4.5mic ~3.5microJy and f_24mic ~85microJy (3sigma). This likely argues against a population dominated by massive and strongly-starbursting (i.e., SFR > ~100 Msol/yr) galaxies as it has been recently suggested from submillimeter/radio and optical studies of similarly-selected GRB hosts. Furthermore we find evidence that some GRBs do not occur in the most infrared-luminous regions -- hence the most actively star-forming environments -- of their host galaxies. Should the GRB hosts be representative of all star-forming galaxies at high redshift, models of infrared galaxy evolution indicate that > ~50% of GRB hosts should have f_24mic > ~100microJy. Unless the identification of GRBs prior to 2001 was prone to strong selection effects biasing our sample against dusty galaxies, we infer in this context that the GRBs identified with the current techniques can not be directly used as unbiased probes of the global and integrated star formation history of the Universe.Comment: ApJ in press, 23 pages, 8 figures (scheduled for the ApJ 10 May 2006, v642 2 issue). Full resolution available at http://perceval.as.arizona.edu/~elefloch/Publis/ms_grb_spitzer.pd

    MAGNETIC RESONANCE (MR) MEASUREMENTS OF THE MASS FLUX IN GAS-SOLID FLUIDIZED BEDS

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    Magnetic Resonance (MR) Imaging was used to measure the time-averaged voidage and particle velocity in a 3D gas-solid fluidized bed. Two different distributors were used. The mass-flux through a horizontal plane was calculated by combining the local voidage and particle velocity measurements. Based on the conservation of mass it was possible to give an error in the combined voidage and particle velocity measurements. It was found that the error in the mass flux was usually small (\u3c 5%), albeit increasing with increasing fluidization velocities
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