59 resultados para Murray-Darling Basin (N.S.W.) -- Environmental aspects.
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The following brief is to ensure standard criteria and format are used for the scoping and environmental assessment of water resources projects leading to the production of an environmental report or Environmental Statement. This volume is one of a series giving guidance on water resources projects. The water resources projects will predominantly comprise drought orders and permits, time limited and permanent licences. Smaller projects, such as spray irrigation licences, will not require an environmental assessment. This document forms the basis for discussions between the Environment Agency North East Region, consultees and the applicant. The process aims to produce a thorough assessment. Each section addresses consecutive elements of the assessment process. Section 2 outlines the structure for a scoping document, section 3 outlines the structure for an Environmental Statement and section 4 gives guidance on the role of an Environmental Action Plan. Appendices 1 and 2 should be used in conjunction with the scoping process and cover a wide range of aspects. However, some projects may not require all of them to be included, whilst for others, the inclusion of additional factors may be appropriate.
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A case study of Atlantic Salmon runs into the R. Tyvi (S. Wales) is presented. Radio tracking of over 200 salmon in 1988 and 1989 has demonstrated that flow is an important factor in modifying both run timing and migratory success. Entry of salmon into the river is typically in response to flow events, and periods of low falling flows delay entry and may directly result in reduced runs into the river. Delayed entry may also increase the proportion of the run migrating after the end of both rod and net fishing seasons. The implications of these results for net and rod catch and catch/effort data are discussed, using both statutory reported catch data and data from specific catch/effort studies. Flow is demonstrated to be a dominant factor in determining the within-season distribution of rod catch and catch/effort during low-flow years. Estuarial seine net catch and catch/effort tend to be controlled more by time of return than by flow although low flows may delay runs. Annual reported rod catch is correlated with flow, which controls in season availability, catchability and consequently the amount of fishing effort. Use of catch or catch/effort data should take account of inter-year variations in flow and other environmental factors. Although catch and catch/effort are valuable indicators of fishery performance, they are inadequate to represent changing stock levels.
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A description of the foraging habitat of a cetacean species is critical for conservation and effective management. We used a fine-scale microhabitat approach to examine patterns in bottlenose dolphin (Tursiops truncatus) foraging distribution in relation to dissolved oxygen, turbidity, salinity, water depth, water temperature, and distance from shore measurements in a highly turbid estuary on the northern Gulf of Mexico. In general, environmental variation in the Barataria Basin marine environment comprises three primary axes of variability (i.e., factors: temperature and dissolved oxygen, salinity and turbidity, and distance and depth) that represent seasonal, spatial-seasonal, and spatial scales, respectively. Foraging sites were differentiated from nonforaging sites by significant differences among group size, temperature, turbidity, and season. Habitat selection analysis on individual variables indicated that foraging was more frequently observed in waters 4–6 m deep, 200–500 m from shore, and at salinity values of around 20 psu. This fine-scale and multivariate approach represents a useful method of exploring the complexity, gradation, and detail of the relationships between environmental variables and the foraging distribution patterns of bottlenose dolphin.
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Between May and October 1990, fecundity, egg size and condition factor of Chrysichthys nigrodigitatus (Lacépède) in the Cross River, Nigeria, were studied. The fecundity (F) of this population varied from 3 046 eggs (total length, L=28.5 cm) to 28 086 eggs (L=64 cm). A mean relative fecundity of 231 eggs/cm or 13 eggs/g of fish was obtained for this population. The fecundity of this population can be estimated with the formula F=2.511 · L 2.30 or F=52.893 · W 0.78 , total length being in cm and weight (W) in g. The mean egg diameter of this population varied from 0.65 mm to 3.54 mm. Condition factor (CF) of the population varied from 0.24 to 1.34 with 0.977 as the mean; 52.8% had CF higher than the mean and 47% had CF above unity. Smaller fish in this population were in better condition than bigger ones. The egg size and condition factor obtained in this study are evidence that the Cross River population of C. nigrodigitatus can provide excellent broodstock.
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Gillnet catches of Oreochromis mortimeri (Trewavas) were studied in the Bumi Basin of Lake Kariba in 1988 and 1989. Total length (TL) was positively correlated with standard length (SL). The linear relationship between TL and SL was TL=1.91 + 1.22 SL (r super(2)=0.982). The relationship between SL and weight in g (W) was of the form W = 0.12 SL super(2.67). Maximum standard length (L sub(max)) was 33 cm and asymptotic length (L sub( infinity )) was 34.7 cm. Monthly ratios of male to female varied between 0.6:1 and 13:1. The mean ratio was 57.4% male: 42.6%female. Monthly condition factors varied between 3.19 and 5.11 in males, and between 3.18 and 5.14 in females. Catches were higher in 1989 compared to 1988 and possible reasons for these differences are discussed.
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This is the report on the Fisheries Aspects of North West Water Authority Schemes to Increase Water Abstraction in West Cumbria by the Egremont and District Anglers’ Association. Existing river pollution and water abstraction in the Ennerdale Lake-River Ehen system is shown to have caused a major deterioration in the conditions in the Ehen fishery. This is reflected by the fact that catches of salmon, sea trout and smelts on the Ehen have all fallen to roughly 6% of the 1965 level; wich is far worse than the deterioration shown in salmon catches for S. W. Cumberland as a whole. Recommendations are made, in the light of proposals by North West Water Authority to increase water abstraction in West Cumbria, to prevent further deterioration in the Ehen fishery in the short term and to improve the situation in the longer term. It contains sections on pollution, water abstraction and fisheries background, flow statistics for and discussion of high water-droughts on the River Ehen, effects of droughts on Tidal Water and a discussion of N.W.W.A. Paper entitled `Water Resources in West Cumbria’ in the light of conditions on the River Ehen.
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Project fact sheet prepared in cooperation with the USDA Natural Resources Conservation Service and the Kings River Conservation District.
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EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring chronologies, developed from cores from Pinyon pines growing on climatically sensitive sites in the north-central Great Basin, have been used to reconstruct precipitation and drought histories of the area from A.D. 1600 to 1982. Analysis of these hydrologic time series helps to place current climatic conditions into the perspective of the past 383 years (since 1600). ... The years 1934 and 1959 were the first and fourth driest while 1934 had the lowest July Palmer Drought Severity Index (PDSI) of the reconstructed records. Nevertheless, the decade of the 1930's is only the seventh driest since 1600; the decade 1953-1962 ranks as the second driest. The driest non-overlapping decade since 1600 was 1856-1865. Interestingly, the second wettest decade was 1932-1941. An examination of 30-year mean precipitation data shows that the driest 30-year period was 1871-1900; 1931-1960 ranks as the fourth driest. The current 30-year period (1951-1980) ranks twelfth.