288 research outputs found
Reported Trip Costs, Gross Revenues, and Net Returns for U.S. Atlantic Pelagic Longline Vessels
Logbook set and trip summary data (containing catch and cost information, respectively) collected by NOAA’s National Marine Fisheries Service (NMFS) were analyzed for U.S. pelagic longline vessels that participated in Atlantic fisheries in 1996. These data were augmented with vessel information from the U.S. Coast Guard. Mean fish weights and ex-vessel prices from NMFS observers and licensed seafood dealers, respectively, were used to estimate gross revenues. Comparisons revealed that net returns varied substantially by vessel size and fishing behavior (i.e. sets per trip, fishing location, season, and swordfish targeting). While the calculated economic effects of proposed regulations will depend on the descriptive statistic chosen for analysis, which itself depends on the type of analysis being conducted, results show that considering heterogeneity within this fleet can have a significant effect on predicted economic consequences
A study of flux lines lattice order and critical current with time of flight small angle neutron scattering
Small angle neutron scattering (SANS) is an historical technique to study the
flux lines lattice (FLL) in a superconductor. Structural characteristics of the
FLL can be revealed, providing fundamental information for the physics of
vortex lattice.
However, the spatial resolution is limited and all the correlation lengths of
order are difficult to extract with precision.
We show here that a time of flight technique reveals the Bragg peak of the
FLL, and also its translational order with a better resolution.
We discuss the implication of these results for pinning mechanisms in a
Niobium sample.Comment: accepted in PR
A BIOECONOMIC ANALYSIS OF MANAGEMENT ALTERNATIVES FOR THE U.S. NORTH ATLANTIC SWORDFISH FISHERY
A bioeconomic model of the North Atlantic swordfish (Xiphias gladius) fishery is developed to evaluate policy-relevant management options as changes from the status quo. The model accounts for heterogeneity in vessel and trip characteristics, including the number of sets placed and catch composition. Results indicate that five-year economic returns to the U.S. Atlantic pelagic longline (PLL) fleet can be increased by reducing juvenile swordfish mortality or fleet size (and possibly changing fleet composition). These policies may not be effective, however, if implemented simultaneously. Domestic management of the swordfish fishery was found to be effective, despite the small share of the international quota. Lastly, producer surpluses earned by the domestic PLL vessel owners are significantly affected by: (1) changes in swordfish demand (due to, for example, the recent chef's boycott), (2) success at negotiating the swordfish quota share, (3) catch rates, and (4) relative costs of heterogeneous vessels and trip behavior.Resource /Energy Economics and Policy,
Economic profile of Florida's marine life industry
The marine life industry in Florida is defined as the harvest of live marine specimens (fish and
invertebrate species including plants, live rock and sand, and small “critters”) for commercial use,
primarily aquariums. This paper summarizes data collected on the industry since 1990, including
total landings, revenues, and trends over time. Regional analysis shows where the primary collecting
areas are located in Florida. Seasonal analysis shows when the majority of landings occur within the
year. Statistics on the number of participants by type (i.e., collector versus wholesaler) provide
insight into the size of the industry. Trends are evaluated in terms of changes across the 9-year
period from 1990 to 1998. In general, the number of licensed collectors has increased substantially,
landings of fish and animal invertebrates peaked in 1994, angelfish dominated the fish landings, live
rock dominated the invertebrate landings, and the average landings per trip have remained relatively
constant. (67pp.
1999 US tropical fish wholesaler survey: results and implications
A survey of marine life wholesalers was initiated in 1999 as a first step towards understanding the
nature of Florida’s marine life industry, the demand for Florida products, and the need for changes in
the way the industry is regulated. Florida firms deal primarily in marine species and collect much of
their own product. Wholesalers outside of Florida handle more freshwater species and purchase most
of their inventory, the majority from overseas suppliers. Dealers predict that the average firm size
will continue to grow as the industry consolidates. Niche markets for eco-friendly product will gain
momentum. In Florida, marketing strategies should point to the high quality of Florida species with
emphasis on the growing popularity of invertebrates. Wholesalers should look to provide buyers of
Florida product with more consistent quantities throughout the year. Resource managers will be
challenged to find ways to protect over-harvested species without interfering with the collection of
abundant species while considering the effect of new regulations. (42pp.
POLICY IMPLICATIONS OF RESTRICTED ACCESS STRATEGIES FOR MULTISPECIES FISHERIES
The commercial fishery that primarily targets king mackerel, stone crab, snappers, groupers and spiny lobster in Monroe and Collier counties is one of the most important commercial fisheries in Florida. These species currently face problems of overfishing and/or over capitalization. A dual-based restricted profit function is used to estimate the economic and technical interactions that exist in this multi-species fishery, primarily using own-price and cross-price elasticities of supply. It is found that the production technology does not exhibit input-output separability and nonjointness-in-inputs over all species groups. This result suggests that these key species may be more efficiently managed as a group, rather than with the use of existing single species regulations. Spiny lobster and stone crab, the dominant value species in the fishery, are shown to have very elastic substitution relationships with king mackerel.Resource /Energy Economics and Policy,
Integral Field Spectroscopy of High-Redshift Star Forming Galaxies with Laser Guided Adaptive Optics: Evidence for Dispersion-Dominated Kinematics
We present early results from an ongoing study of the kinematic structure of
star-forming galaxies at redshift z ~ 2 - 3 using integral-field spectroscopy
of rest-frame optical nebular emission lines in combination with Keck laser
guide star adaptive optics (LGSAO). We show kinematic maps of 3 target galaxies
Q1623-BX453, Q0449-BX93, and DSF2237a-C2 located at redshifts z = 2.1820,
2.0067, and 3.3172 respectively, each of which is well-resolved with a PSF
measuring approximately 0.11 - 0.15 arcsec (~ 900 - 1200 pc at z ~ 2-3) after
cosmetic smoothing. Neither galaxy at z ~ 2 exhibits substantial kinematic
structure on scales >~ 30 km/s; both are instead consistent with largely
dispersion-dominated velocity fields with sigma ~ 80 km/s along any given line
of sight into the galaxy. In contrast, DSF2237a-C2 presents a well-resolved
gradient in velocity over a distance of ~ 4 kpc with peak-to-peak amplitude of
140 km/s. It is unlikely that DSF2237a-C2 represents a dynamically cold
rotating disk of ionized gas as the local velocity dispersion of the galaxy
(sigma = 79 km/s) is comparable to the observed shear. Using extant
multi-wavelength spectroscopy and photometry we relate these kinematic data to
physical properties such as stellar mass, gas fraction, star formation rate,
and outflow kinematics and consider the applicability of current galaxy
formation models.[Abridged]Comment: 19 pages, 10 figures (5 color); accepted for publication in ApJ.
Version with full-resolution figures is available at
http://www.astro.caltech.edu/~drlaw/Papers/OSIRIS_data1.pd
International trade in live, ornamental "fish" in the US & Florida
The importance of international markets as a source of live, ornamental “fish” supply is growing due
to more stringent wild-harvest regulations in Florida. In addition, foreign markets are increasing in
importance as a source of demand for Florida purveyors of live, ornamental “fish”. Florida plays an
important role in this growing international market. Trends in imports and exports of live,
ornamental “fish” are described for two primary data sets: U.S. Customs and U.S. Fish and Wildlife
Service. These trends are described primarily for the 1994-98 period for Florida and the United
States. Florida imports and exports are described for the two major ports: Miami and Tampa. The
most important trading countries are also described. This information will help Florida purveyors of
live, ornamental “fish” better understand the international markets upon which they have become
more dependent. (PDF has 18 pages
Measurement of [OIII] Emission in Lyman Break Galaxies
Measurements of [OIII] emission in Lyman Break galaxies (LBGs) at z>3 are
presented. Four galaxies were observed with narrow-band filters using the
Near-IR Camera on the Keck I 10-m telescope. A fifth galaxy was observed
spectroscopically during the commissioning of NIRSPEC, the new infrared
spectrometer on Keck II. The emission-line spectrum is used to place limits on
the metallicity. Comparing these new measurements with others available from
the literature, we find that strong oxygen emission in LBGs may suggest
sub-solar metallicity for these objects. The [OIII]5007 line is also used to
estimate the star formation rate (SFR) of the LBGs. The inferred SFRs are
higher than those estimated from the UV continuum, and may be evidence for dust
extinction.Comment: 25 pages, including 6 figures. Accepted for publication in Ap
Structure of Flux Line Lattices with Weak Disorder at Large Length Scales
Dislocation-free decoration images containing up to 80,000 vortices have been
obtained on high quality BiSrCaCuO superconducting
single crystals. The observed flux line lattices are in the random manifold
regime with a roughening exponent of 0.44 for length scales up to 80-100
lattice constants. At larger length scales, the data exhibit nonequilibrium
features that persist for different cooling rates and field histories.Comment: 4 pages, 3 gif images, to appear in PRB rapid communicatio
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