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81.
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83.
L. Richard Little André E. Punt Bruce D. Mapstone Gavin A. Begg Barry Goldman Ashley J. Williams 《Ecological modelling》2009
Individual transferable quotas (ITQs) are increasingly seen as a way to make fisheries more profitable and halt over-capitalisation. ITQs allocate to users of a resource a share of a total allowable catch (TAC) which they are free to use, lease, or sell. We outline an approach to modelling the effect of an ITQ system in a multi-species, multi-sector fishery and apply it to the Coral Reef Fin Fish Fishery (CRFFF) in Queensland, Australia. An ITQ model, based on the assumption that operators seek to maximize profits, simulates the use of tradeable quota units by operators in the fishery, taking account of the initial quota allocation to operators, seasonal fish prices and individual operator variable costs, their fishing efficiency and experience, and constraints on vessel movements. Rationalization of the fishery is predicted to occur under an ITQ system for the CRFFF, which will lead to reductions in effort, increases in profits, and changes over time in quota prices. The ecological consequences of transferable quota in the multi-species fishery are seen in the catch and discard levels of the less profitable species, even though a TAC was set. This had flow-on effects on biomass. For example, simulations showed that the TAC for the primary target species, coral trout, was used more fully than that for a less valuable target species, red throat emperor, and that this was achieved through increased discarding of red throat emperor. Catches of both coral trout and red throat emperor that were derived from the model were higher than those recently observed in the fishery. The effort predicted by the model, however, closely approximated the actual effort observed in the fishery following implementation of ITQ management. 相似文献
84.
In 1997 a workshop was held on the subject of how to cope with accelerating technologies. These are industries such as aviation, air traffic control and biotechnology, amongst others, where the rate of technological development is significant. A number of papers were presented from a range of viewpoints and in a variety of different industrial contexts. The papers ranged from theoretical models to help understand the process of acceleration and its impact on organisational learning, to practical analyses of future potential risks in specific accelerating industries such as air traffic control. The aim of the papers and the workshop as a whole was to provide insight into the problems associated with accelerating technologies, and thereby derive measures to control or cope with such acceleration. The problems arising from acceleration, as predicted by the theoretical models and evidenced by experiences in accelerating industries (e.g. aviation) are manifold. Two examples of particular problems are unforeseen risks in an industry (a lack of forward vision), and a failure to learn adequately (i.e. in time) from incidents occurring in an organisation (a lack of constructive hindsight). There is also an incipient danger of society being driven by technology rather than being led by social needs. Even if each technology ultimately becomes ‘ultra-safe’, it will nevertheless have its own ‘event horizon’, limiting useful further progress. Each of the papers from the workshop is summarised and integrated into a three-part synopsis of the workshop. This covers the context of accelerating technologies, modelling their impacts, and deriving coping strategies. Four of the papers are included in their entirety as separate papers in their own right in this special issue of Safety Science. 相似文献
85.
Trace Element Concentrations and Bioindicator Responses in Tree Swallows from Northwestern Minnesota 总被引:5,自引:0,他引:5
Custer CM Custer TW Warburton D Hoffman DJ Bickham JW Matson CW 《Environmental monitoring and assessment》2006,118(1-3):247-266
Extremely high concentrations of cadmium (3.5 μg/g dry wgt.) and elevated concentrations of chromium (>10 μg/g dry wgt.) and mercury (1.6 μg/g dry wgt.) were reported in waterbird tissues at Agassiz National Wildlife Refuge in northwestern Minnesota in 1994. Tree
swallows (Tachycineta bicolor) were studied during 1998–2001 at three drainages into the Refuge, two pools on the Refuge, and at a nearby reference location
to document whether high levels of contaminants were still present, and if so to quantify the source and severity of the contamination.
Trace elements were measured in tree swallow eggs, livers, and diet. Reproductive success and bioindicator responses were
monitored. In 2000, water was drawn down on Agassiz Pool, one of the main pools on the Refuge. This presented an opportunity
to evaluate the response of trace element concentrations in the diet and tissues of tree swallows after reflooding. High concentrations
of trace elements were not detected in swallow tissues, nor were there differences among locations. Less than 20% of swallow
samples had detectable concentrations of cadmium or chromium. Mercury concentrations were low and averaged <0.25 μg/g dry wgt. in swallow tissues. Trace elements, including mercury, did not increase in tree swallows following the 2000 drawdown
at Agassiz Pool. Hatching success and survival of nestlings to 12 days-of-age for tree swallows on the Refuge were similar
to the national average and consistent with background trace element concentrations. Bioindicator measurements were within
the normal ranges as well. 相似文献
86.
Schewe Rebecca L. Hoffman David Witt Joseph Shoup Brian Freeman Matthew 《Environmental management》2020,65(1):74-87
Environmental Management - This study examines the engagement of Vietnamese American commercial fisheries stakeholders in the US Gulf Coast with state and federal agencies and the role that citizen... 相似文献
87.
Buscemi DM Hoffman DJ Vyas NB Spann JW Kuenzel WJ 《Environmental pollution (Barking, Essex : 1987)》2007,148(1):312-315
Effects of field application levels of wildfire control chemicals, Phos-Chek G75-F (PC) and Silv-Ex (SE), were examined on red-winged blackbird (Agelaius phoeniceus) embryos. Embryos were more sensitive to PC and SE when eggs were immersed for 10s at an early developmental stage (days 3-5 of incubation) than at a later stage (days 6-9 of incubation). The LC(50) (concentration causing 50% mortality) for early stage embryos exposed to PC was 213.3g/L (slope=1.6; 95% confidence interval [CI]=129.1-326.1). The no observed effect concentration (NOEC) was below 135g PC/L, which caused a significant increase in embryonic mortality and represents the lowest field coverage level of 1gal/100feet(2). The LC(50) for early stage embryos exposed to SE was 19.8g/L (slope=1.5; 95% CI=11.7-52.2). Significant mortality was observed at 10g SE/L and marginal at 7.5g SE/L with an apparent NOEC around 5g SE/L. Neither chemical resulted in apparent developmental malformations. 相似文献
88.
J. M. Davidson Timothy R. B. Johnson Jr. David T. Rigdon Barry H. Thompson 《黑龙江环境通报》1984,4(5):355-363
Obstetric ultrasonography has made the prenatal diagnosis of gastroschisis and omphalocele more common. We present illustrative cases 2nd review the ultrasonographic features. Because of the increased risk of concomitant abnormalities (including trisomies) with omphalocele, full evaluation is indicated when this diagnosis is suspected. Recent perinatal approaches to delivery have favoured caesarean section. without scientific evidence that outcome is improved. Our experience. as well as a review of the literature, suggests that the outcome for vaginally delivered infants is acceptable. A prospective study of this question is needed. 相似文献
89.
Saikat SQ Carter JE Mehra A Smith B Stewart A 《Environmental geochemistry and health》2004,26(4):395-401
Endemic goitre was prevalent in the population of Derbyshire in the UK for many centuries until it declined from the 1930s. A contemporary medical survey showed that endemicity of goitre was particularly higher in the Carboniferous limestone areas of the Derbyshire-Peak District. Unlike classical goitrous areas of the world, where the distribution of goitre has been found to be related to the iodine content in the environment, there is no such relationship reported for the Derbyshire-Peak District area. The present study reviews the presence of endemic goitre in this area with reference to iodine in different environmental media using past and present data. In comparison with the world average values, the iodine contents in the soil and sediment in the Peak District are not deficient, but compared to England, Wales and Scotland averages, these levels are low. As no information on the mobility and bioavailability of iodine of this area is available, a cautious approach is necessary before any assumption is made on the aetiology of endemic goitre. The study also discusses some hypotheses relating to the possible cause of endemic goitre in the limestone areas. Further research needs are suggested depending on the land use and geochemistry of the Peak District to determine the underlying causes of the former endemic goitre in this area. 相似文献
90.
Blus LJ Henny CJ Hoffman DJ Grove RA 《Environmental pollution (Barking, Essex : 1987)》1995,89(3):311-318
Waterfowl and passerines in northern Idaho in 1987 had high levels of lead in their blood and tissues that originated primarily from mining and smelting activities. Four Canada geese (Branta canadensis) and one common goldeneye (Bucephala clangula) found dead contained 8 to 38 microg/g (wet mass) of lead in their livers. These levels exceed the lower lethal limit of 5 microg/g in experimental birds. Two of the Canada geese (one each from the contaminated and reference areas) died with ingested lead shotgun pellets (shot) in their gizzards, whereas the other three birds from the contaminated area contained no ingested shot and evidently died from ingesting environmental lead in sediment or biota. Lead burdens in most American robins (Turdus migratorius) and mallards (Anas platyrhynchos) were high, whereas those in tree swallows (Tachycineta bicolor) were slightly elevated. Lead accumulated to potentially hazardous levels in blood and tissues of some nestling robins (maxima of 0.87 microg/g in blood and 5.6 microg/g in liver) and mallards (maxima of 10.2 microg/g in blood and 2.8 microg/g in liver). In mallards, lead levels and associated physiological characteristics of blood were significantly different in juveniles (HY) versus adults (AHY). Activity of delta-aminolevulinic acid dehydratase (ALAD) was about 87 to 95% lower than values for control birds in experimental studies. Activity of ALAD was significantly inversely correlated with blood lead levels. Cadmium was detected in kidneys of most birds, but even the maximum concentration of 7.5 microg/g in an AHY mallard was below known harmful levels. 相似文献