14 resultados para Active Management

em Aquatic Commons


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This article outlines the outcome of work that set out to provide one of the specified integral contributions to the overarching objectives of the EU- sponsored LIFE98 project described in this volume. Among others, these included a requirement to marry automatic monitoring and dynamic modelling approaches in the interests of securing better management of water quality in lakes and reservoirs. The particular task given to us was to devise the elements of an active management strategy for the Queen Elizabeth II Reservoir. This is one of the larger reservoirs supplying the population of the London area: after purification and disinfection, its water goes directly to the distribution network and to the consumers. The quality of the water in the reservoir is of primary concern, for the greater is the content of biogenic materials, including phytoplankton, then the more prolonged is the purification and the more expensive is the treatment. Whatever good that phytoplankton may do by way of oxygenation and oxidative purification, it is eventually relegated to an impurity that has to be removed from the final product. Indeed, it has been estimated that the cost of removing algae and microorganisms from water represents about one quarter of its price at the tap. In chemically fertile waters, such as those typifying the resources of the Thames Valley, there is thus a powerful and ongoing incentive to be able to minimise plankton growth in storage reservoirs. Indeed, the Thames Water company and its predecessor undertakings, have a long and impressive history of confronting and quantifying the fundamentals of phytoplankton growth in their reservoirs and of developing strategies for operation and design to combat them. The work to be described here follows in this tradition. However, the use of the model PROTECH-D to investigate present phytoplankton growth patterns in the Queen Elizabeth II Reservoir questioned the interpretation of some of the recent observations. On the other hand, it has reinforced the theories underpinning the original design of this and those Thames-Valley storage reservoirs constructed subsequently. The authors recount these experiences as an example of how simulation models can hone the theoretical base and its application to the practical problems of supplying water of good quality at economic cost, before the engineering is initiated.

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Automatic recording instruments provide the ideal means of recording the responses of rivers, lakes and reservoirs to short-term changes in the weather. As part of the project ‘Using Automatic Monitoring and Dynamic Modelling for the Active Management of Lakes and Reservoirs', a family of three automatic monitoring stations were designed by engineers at the Centre for Ecology and Hydrology in Windermere to monitor such responses. In this article, the authors describe this instrument network in some detail and present case studies that illustrate the value of high resolution automatic monitoring in both catchment and reservoir applications.

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Steady-state procedures, of their very nature, cannot deal with dynamic situations. Statistical models require extensive calibration, and predictions often have to be made for environmental conditions which are often outside the original calibration conditions. In addition, the calibration requirement makes them difficult to transfer to other lakes. To date, no computer programs have been developed which will successfully predict changes in species of algae. The obvious solution to these limitations is to apply our limnological knowledge to the problem and develop functional models, so reducing the requirement for such rigorous calibration. Reynolds has proposed a model, based on fundamental principles of algal response to environmental events, which has successfully recreated the maximum observed biomass, the timing of events and a fair simulation of the species succession in several lakes. A forerunner of this model was developed jointly with Welsh Water under contract to Messrs. Wallace Evans and Partners, for use in the Cardiff Bay Barrage study. In this paper the authors test a much developed form of this original model against a more complex data-set and, using a simple example, show how it can be applied as an aid in the choice of management strategy for the reduction of problems caused by eutrophication. Some further developments of the model are indicated.

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Management options for the Silver Springs free-ranging rhesus macaque population range from removal to active maintenance of the population in situ. Selection of a management option is dependent upon which issues are perceived to be true problems. Management options are presented along with their effectiveness in dealing with issues previously described.(31 page document)

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Mid-frequency active (MFA) sonar emits pulses of sound from an underwater transmitter to help determine the size, distance, and speed of objects. The sound waves bounce off objects and reflect back to underwater acoustic receivers as an echo. MFA sonar has been used since World War II, and the Navy indicates it is the only reliable way to track submarines, especially more recently designed submarines that operate more quietly, making them more difficult to detect. Scientists have asserted that sonar may harm certain marine mammals under certain conditions, especially beaked whales. Depending on the exposure, they believe that sonar may damage the ears of the mammals, causing hemorrhaging and/or disorientation. The Navy agrees that the sonar may harm some marine mammals, but says it has taken protective measures so that animals are not harmed. MFA training must comply with a variety of environmental laws, unless an exemption is granted by the appropriate authority. Marine mammals are protected under the Marine Mammal Protection Act (MMPA) and some under the Endangered Species Act (ESA). The training program must also comply with the National Environmental Policy Act (NEPA), and in some cases the Coastal Zone Management Act (CZMA). Each of these laws provides some exemption for certain federal actions. The Navy has invoked all of the exemptions to continue its sonar training exercises. Litigation challenging the MFA training off the coast of Southern California ended with a November 2008 U.S. Supreme Court decision. The Supreme Court said that the lower court had improperly favored the possibility of injuring marine animals over the importance of military readiness. The Supreme Court’s ruling allowed the training to continue without the limitations imposed on it by other courts. (pdf contains 20pp.)

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Shellfish bed closures along the North Carolina coast have increased over the years seemingly concurrent with increases in population (Mallin 2000). More and faster flowing storm water has come to mean more bacteria, and fecal indicator bacterial (FIB) standards for shellfish harvesting are often exceeded when no source of contamination is readily apparent (Kator and Rhodes, 1994). Could management reduce bacterial loads if the source of the bacteria where known? Several potentially useful methods for differentiating human versus animal pollution sources have emerged including Ribotyping and Multiple Antibiotic Resistance (MAR) (US EPA, 2005). Total Maximum Daily Load (TMDL) studies on bacterial sources have been conducted for streams in NC mountain and Piedmont areas (U.S. EPA, 1991 and 2005) and are likely to be mandated for coastal waters. TMDL analysis estimates allowable pollutant loads and allocates them to known sources so management actions may be taken to restore water to its intended uses (U.S. EPA, 1991 and 2005). This project sought first to quantify and compare fecal contamination levels for three different types of land use on the coast, and second, to apply MAR and ribotyping techniques and assess their effectiveness for indentifying bacterial sources. Third, results from these studies would be applied to one watershed to develop a case study coastal TMDL. All three watershed study areas are within Carteret County, North Carolina. Jumping Run Creek and Pettiford Creek are within the White Oak River Basin management unit whereas the South River falls within the Neuse River Basin. Jumping Run Creek watershed encompasses approximately 320 ha. Its watershed was a dense, coastal pocosin on sandy, relic dune ridges, but current land uses are primarily medium density residential. Pettiford Creek is in the Croatan National Forest, is 1133 ha. and is basically undeveloped. The third study area is on Open Grounds Farm in the South River watershed. Half of the 630 ha. watershed is under cultivation with most under active water control (flashboard risers). The remaining portion is forested silviculture.(PDF contains 4 pages)

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The study was an endeavor to bring forward a concise, factual description of the salient features of the present status of artisanal fisheries resources and its management for sustainable development of fishing communities in Teknaf coast, Cox’s Bazar, Bangladesh. This study was conducted through 14 fishing villages of 4 Unions in Teknaf Upazila. As a hub of various fisheries deeds, a comprehensive coastal fisheries census, conducted on the coast during the study period, revealed that about 566 fishing fleet of two types, 1263 fishing gears of seven kinds, 6466 fishermen were being involved in fishing at Naaf river estuary. The catch composition of the coastal fishing was found 52 finfish species, 10 shrimp and 3 crabs. The unique potentialities provided by mostly affluent fisheries resources are needed to be tapped and channelized in the appropriate direction for maintaining a paragon of these fisheries resources of coastal area and for pursuing ecologically sustainable development via environment friendly intrinsic exploration and exploitation. “Community Based Fisheries Co-management” program should initiate immediately for the fisherman community of Naaf river estuary of Teknaf coastal region. This will go along way to help sustain the coastal fisheries resources with active participation of the fishermen

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An assessment of three methods of fish capture, to establish the best fishing method which reflects the best range of sizes and species of fish in a given area. The methods used were trawl netting, electrofishing, and seine netting which were assessed on the Crossens drainage system near Southport. The report also includes a study of roach / bream hybrids that were found at the site, which focuses on their distinguishing features and compared with the features of roach and bream.

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Squaretail coralgrouper (Plectropomus areolatus) were captured and tagged at a fish spawning aggregation (FSA) site with conventional and acoustic tags to assess their vulnerability to fishing and spatial dynamics during reproductive periods. Males outnumbered females in catch and, on average, were larger than females. Findings revealed a high vulnerability to fishing, particularly during reproductive periods, and most fish were recaptured within the 5-month spawning season and within 10−12 km of the aggregation site. Individual and sex-specific variability in movement to, and residency times at, the FSA site indicates that individual monthly spawning aggregations represent subsets of the total reproductive population. Some individuals appeared to move along a common migratory corridor to reach the FSA site. Sex-specific behavioral differences, particularly longer residency times, appear to increase the vulnerability of reproductively active males to fishing, particularly within a FSA, which could reduce reproductive output. Both fishery-dependent and fishery-independent data indicate that only males were present within the first month of aggregation. The combined results indicate that reproductively active P. areolatus are highly vulnerable to fishing and that FSAs and migratory corridors of reproductively active fish should be incorporated into marine protected areas. The capture of P. areolatus during reproductive periods should be restricted as part of a comprehensive management strateg

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The implementation of Puerto Rican Regulation No. 6768, which overhauled the existing fishery management framework, generated considerable hostility towards local managers. Among the controversial management measures adopted in 2004 were the assignment of fishing licenses based on fishing income, the establishment of closed seasons, and new minimum size restrictions for commercially valuable species. Though tensions have subsided, considerable opposition to these regulations remains. This paper provides a characterization of the current population of active small-scale fishermen, discusses their perceptions about the biological and socio-economic condition of the fishery, and describes their attitudes towards the new management framework. This study revealed that the number of active fishermen decreased from 1,731 in 1988 to 868 in 2008. Although a declining resource base was one of the main drivers behind these waning participation statistics, rising fuel costs and burdensome regulations exacerbated the rate of attrition. The majority of the fishermen were middleaged men (50 years) with moderate levels of formal education and high levels of fishing dependence which limited their employment opportunities outside the fishery. Most of the vessels were small (20 ft) and outfitted with a single outboard engine (80 hp). Hook and line and SCUBA were dominant gears because of their versatility and cost effectiveness. Fishermen suggested that their opposition to the regulations would continue unless they were afforded greater regulatory flexibility and provided with a larger role in the decision-making process. Fishermen were adamant about the need to reconsider the income reporting requirements to secure a fishing license because of the potential for losing public assistance benefits. They also objected to increasing the minimum size of many deepwater snapper (Lutjanidae) and grouper (Serranidae) species because it forced them to discard dead fish, a practice they consider wasteful since these species do not survive the ascent to the surface once hooked.

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The fishery for deepwater precious corals in the Hawaiian Islands has experienced an on-and-off history for almost 40 years. In spite of this, research, driven primarily by the precious coral jewelry industry, remains active. In this paper, the results of deepwater surveys in 2000 and 2001 are reported. In summary, a new bed on the summit of Cross Seamount is described and revised estimates of MSY’s for pink coral, Corallium secundum; red coral, Corallium regale; and gold coral, Ger ardia sp., in the two known beds off Makapuu, Oahu, and Keahole Point, Hawaii, in the main Hawaiian Islands, are presented. The population dynamics of each species is described, as well as their ecological limits on Hawaii’s deep reefs, island shelves, and seamounts. The local supply of precious coral in the main Hawaiian Islands is sufficient to support the local industry, but cost/ benefits of selective harvest requirements and weather constraints limit profitability of the fish

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Southeast Bering Sea Carrying Capacity (SEBSCC, 1996–2002) was a NOAA Coastal Ocean Program project that investigated the marine ecosystem of the southeastern Bering Sea. SEBSCC was co-managed by the University of Alaska Fairbanks, NOAA Alaska Fisheries Science Center, and NOAA Pacific Marine Environmental Laboratory. Project goals were to understand the changing physical environment and its relationship to the biota of the region, to relate that understanding to natural variations in year-class strength of walleye pollock (Theragra chalcogramma), and to improve the flow of ecosystem information to fishery managers. In addition to SEBSCC, the Inner Front study (1997–2000), supported by the National Science Foundation (Prolonged Production and Trophic Transfer to Predators: Processes at the Inner Front of the S.E. Bering Sea), was active in the southeastern Bering Sea from 1997 to 1999. The SEBSCC and Inner Front studies were complementary. SEBSCC focused on the middle and outer shelf. Inner Front worked the middle and inner shelf. Collaboration between investigators in the two programs was strong, and the joint results yielded a substantially increased understanding of the regional ecosystem. SEBSCC focused on four central scientific issues: (1) How does climate variability influence the marine ecosystem of the Bering Sea? (2) What determines the timing, amount, and fate of primary and secondary production? (3) How do oceanographic conditions on the shelf influence distributions of fish and other species? (4) What limits the growth of fish populations on the eastern Bering Sea shelf? Underlying these broad questions was a narrower focus on walleye pollock, particularly a desire to understand ecological factors that affect year-class strength and the ability to predict the potential of a year class at the earliest possible time. The Inner Front program focused on the role of the structural front between the well-mixed waters of the coastal domain and the two-layer system of the middle domain. Of special interest was the potential for prolonged post-spring-bloom production at the front and its role in supporting upper trophic level organisms such as juvenile pollock and seabirds. Of concern to both programs was the role of interannual and longer-term variability in marine climates and their effects on the function of sub-arctic marine ecosystems and their ability to support upper trophic level organisms.

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The priorities for the revised National Plan of Action include: strengthening current regulations; improved data collection of landings; identifying breeding and nursery grounds; study of ecology and biology of sharks; improved data acquisition of shark products and trade; and active enforcement at sea, landing sites and markets.

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A casual study of the hydrological map of Uganda would convince every serious fisherman and fisheater that he is most favoured to be in Uganda. The extent and distribution of the country's aquatic system plus the rich variety of fish species there is promises a fishery potential of considerable magnitude: The open waterways comprised by the Uganda portions of Lakes Victoria, Albert and Edward; and Lakes Kyoga, George plus minor lakes Wamala, Kijanebarora, mutanda, etc. occupy about 15% of the total surface area (91,000 m2; Depart. Land Survey, 1962). Most of the nation's fish supplies are currontly from this source. 1.2. A rich network of permanent and seasonal rivers and streams filling and/or emptying various water systems covers most of Uganda. This aquatic network is associated with a fish fauna whose immense significance as a source of protein is perhaps better appreciated by the local subsistance fisherman and consumer than by the fisheries scientist and manager in this country. Many species of this fish fauna have strong affinities with the open water systems while some are typically riverine. 1.3. Then there are wetlands composed mainly of expanses of swamp, but including some areas of bog. These cover about 2% of the country. While the variety of fish fauna found here is limited by the rather hostile nature of the environment (comparatively de-oxygenated under a canopy of dense stands of emergont vegetation) several specialised fishes e.g. Clarias spp. and Protpterus aethiopicus (Kamongo) occur here. Availability of permanent and seasonal sources of water, well distributed throughout most areas of Uganda, opens up immense potential for a variety of aquaculture practices. However, while active exploitation of much of these fishery resources is currently underway, important questions regarding the magnitudes of the various resource potentials and dynamics, and about suitable levels and modes of exploitation, are yet unanswered. These gaps in knowledge go about the fishery resources of Uganda would hinder formulation of adequate development and management schemes. This short paper examines some of the above problems and suggests some approaches towards balanced oxploitation and management of the fisheries of Uganda.