284 research outputs found

    Stock assessment of Queensland east coast blue swimmer crab (Portunus armatus)

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    Blue swimmer crabs are widely distributed in Australia. They are found along the western coast of Australia, across Australia’s north and down the east coast to the New South Wales–Victoria border. This assessment of the north eastern Australian (Queensland) blue swimmer crab biological stock, informs the status of the stock and the harvest strategy development under Queensland’s Sustainable Fisheries Strategy. This stock assessment used a length-structured model with a monthly time step. Data inputs included total harvests, standardised catch rates, and carapace width size compositions. Model analyses suggested that exploitable (legal sized male) biomass fell to around 33 per cent of unfished biomass in 2018–19. The blue swimmer crab harvest control rule recommends an initial harvest limit of 129 t to begin rebuilding the stock to levels consistent with 60% of unfished biomass

    Pleasure and pedagogy: the consumption of DVD add-ons among Irish teenagers

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    This article addresses the issue of young people and media use in the digital age, more specifically the interconnection between new media pleasures and pedagogy as they relate to the consumption of DVD add-ons. Arguing against the view of new media as having predominantly detrimental effects on young people, the authors claim that new media can enable young people to develop media literacy skills and are of the view that media literacy strategies must be based on an understanding and legitimating of young people's use patterns and pleasures. The discussion is based on a pilot research project on the use patterns and pleasures of use with a sample of Irish teenagers. They found that DVDs were used predominantly in the home context, and that, while there was variability in use between the groups, overall they developed critical literacy skills and competences which were interwoven into their social life and projects of identity construction. The authors suggest that these findings could be used to develop DVDs and their add-on features as a learning resource in the more formal educational setting and they go on to outline the potential teaching benefits of their use across a range of pedagogical areas

    Stock assessment of the Australian east coast sea mullet (Mugil cephalus) fishery 2018

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    The sea mullet (Mugil cephalus) is found in tropical and subtropical waters around the world. On the east coast of Australia, sea mullet are harvested from a single continous stock which occurs from Baffle Creek in Queensland to Eden in New South Wales. Sea mullet undertake annual migrations along ocean beaches to spawn that make them susceptible to overfishing. This stock assessment covers the Australian east coast and incorporates Queensland and NSW catch data up to 2016. The vast majority of the harvest is taken in the commercial fishery, with the catch in NSW exceeding the Queensland catch (approximately 65% and 35% of the catch respectively). The current assessment combined data in an annual age-structured population model tailored for the biology, management and fishing history of sea mullet and estimates the sea mullet biomass in 2016 is around 50 per cent of unfished exploitable biomass (all sectors and jurisdictions). Biological information for sea mullet has revealed a cyclic pattern of new fish recruitment over years. This has produced a cyclic fluctuation in the exploitable biomass results with a midpoint at around 50% of virgin levels which is trending downward. The final year of the model occurs during a downward phase in a long term cycle of biomass peaks and troughs and fishing could exacerbate this downward biomass trend. The assessment noted that the Bundaberg to Noosa stock range was experiencing below average harvests. Further assessment of the extent of regional decline will increase our understanding of the relationshop between historical levels of fishing and environmental change. The assessment provides estimates of the maximum sustainable yield (MSY) and recommends a total allowable catch to rebuild the stock to the Sustainable Fisheries Strategy (SFS) longer term target of 60% unfished biomass (as a proxy for MEY) by 2027

    Harvest strategy evaluation to optimise the sustainability and value of the Queensland scallop fishery. Queensland scallop fishery - FRDC Project No 2006/024 Final Report

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    Objective 1. Measure spatial and temporal trawl frequency of scallop grounds using VMS data. This will provide a relative measure of how often individual undersized scallops are caught and put through a tumbler 2. Estimate discard mortality and growth rates for saucer scallops using cage experiments. 3. Evaluate the current management measures, in particular the seasonal closure, rotational closure and seasonally varying minimum legal sizes using stock assessment and management modeling models. Recommend optimal range of management measures to ensure long-term viability and value of the Scallop fishery based on a formal management strategy evaluation. Outcomes acheived to date: 1. Improved understanding of the survival rates of discarded sub-legal scallops; 2. Preliminary von Bertalanffy growth parameters using data from tagged-and-released scallops; 3. Changing trends in vessels and fishing gear used in the Queensland scallop fishery and their effect on scallop catch rates over time using standardised catch rates quantified; 4. Increases in fishing power of vessels operating in the Queensland scallop fishery quantified; 5. Trawl intensity mapped and quantified for all Scallop Replenishment Areas; 6. Harvest Strategy Evaluations completed

    A-dependence of nuclear transparency in quasielastic A(e,e'p) at high Q^2

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    The A-dependence of the quasielastic A(e,e'p) reaction has been studied at SLAC with H-2, C, Fe, and Au nuclei at momentum transfers Q^2 = 1, 3, 5, and 6.8 (GeV/c)^2. We extract the nuclear transparency T(A,Q^2), a measure of the average probability that the struck proton escapes from the nucleus A without interaction. Several calculations predict a significant increase in T with momentum transfer, a phenomenon known as Color Transparency. No significant rise within errors is seen for any of the nuclei studied.Comment: 5 pages incl. 2 figures, Caltech preprint OAP-73

    Study of the B^0 Semileptonic Decay Spectrum at the Upsilon(4S) Resonance

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    We have made a first measurement of the lepton momentum spectrum in a sample of events enriched in neutral B's through a partial reconstruction of B0 --> D*- l+ nu. This spectrum, measured with 2.38 fb**-1 of data collected at the Upsilon(4S) resonance by the CLEO II detector, is compared directly to the inclusive lepton spectrum from all Upsilon(4S) events in the same data set. These two spectra are consistent with having the same shape above 1.5 GeV/c. From the two spectra and two other CLEO measurements, we obtain the B0 and B+ semileptonic branching fractions, b0 and b+, their ratio, and the production ratio f+-/f00 of B+ and B0 pairs at the Upsilon(4S). We report b+/b0=0.950 (+0.117-0.080) +- 0.091, b0 = (10.78 +- 0.60 +- 0.69)%, and b+ = (10.25 +- 0.57 +- 0.65)%. b+/b0 is equivalent to the ratio of charged to neutral B lifetimes, tau+/tau0.Comment: 14 page, postscript file also available at http://w4.lns.cornell.edu/public/CLN
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