66 research outputs found
Interactions between a Trawl Fishery and Spatial Closures for Biodiversity Conservation in the Great Barrier Reef World Heritage Area, Australia
Background\ud
The Queensland East Coast Otter Trawl Fishery (ECOTF) for penaeid shrimp fishes within Australia's Great Barrier Reef World Heritage Area (GBRWHA). The past decade has seen the implementation of conservation and fisheries management strategies to reduce the impact of the ECOTF on the seabed and improve biodiversity conservation. New information from electronic vessel location monitoring systems (VMS) provides an opportunity to review the interactions between the ECOTF and spatial closures for biodiversity conservation.\ud
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Methodology and Results\ud
We used fishing metrics and spatial information on the distribution of closures and modelled VMS data in a geographical information system (GIS) to assess change in effort of the trawl fishery from 2001â2009 and to quantify the exposure of 70 reef, non-reef and deep water bioregions to trawl fishing. The number of trawlers and the number of days fished almost halved between 2001 and 2009 and new spatial closures introduced in 2004 reduced the area zoned available for trawl fishing by 33%. However, we found that there was only a relatively minor change in the spatial footprint of the fishery as a result of new spatial closures. Non-reef bioregions benefited the most from new spatial closures followed by deep and reef bioregions.\ud
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Conclusions/Significance\ud
Although the catch of non target species remains an issue of concern for fisheries management, the small spatial footprint of the ECOTF relative to the size of the GBRWHA means that the impact on benthic habitats is likely to be negligible. The decline in effort as a result of fishing industry structural adjustment, increasing variable costs and business decisions of fishers is likely to continue a trend to fish only in the most productive areas. This will provide protection for most benthic habitats without any further legislative or management intervention
HESS VHE Gamma-Ray Sources Without Identified Counterparts
The detection of gamma rays in the very-high-energy (VHE) energy range (100
GeV--100 TeV) provides a direct view of the parent population of
ultra-relativistic particles found in astrophysical sources. For this reason,
VHE gamma rays are useful for understanding the underlying astrophysical
processes in non-thermal sources. We investigate unidentified VHE gamma-ray
sources that have been discovered with HESS in the most sensitive blind survey
of the Galactic plane at VHE energies conducted so far. The HESS array of
imaging atmospheric Cherenkov telescopes (IACTs) has a high sensitivity
compared with previous instruments(~ 0.01 Crab) in 25 hours observation time
for a 5 sigma point-source detection), and with its large field of view, is
well suited for scan-based observations. The on-going HESS survey of the inner
Galaxy has revealed a large number of new VHE sources, and for each we attempt
to associate the VHE emission with multi-wavelength data in the radio through
X-ray wavebands. For each of the eight unidentified VHE sources considered
here, we present the energy spectra and sky maps of the sources and their
environment. The VHE morphology is compared with available multi-wavelength
data (mainly radio and X-rays). No plausible counterparts are found
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