950 resultados para freshwater Dinophyta


Relevância:

20.00% 20.00%

Publicador:

Resumo:

The value of specially designated sites in conserving biodiversity has been a hotly debated issue for many years. The debate has recently been given fresh impetus by the creation of Natural England, the new Government Agency responsible for the protection and enhancement of the natural environment in England, and the challenges facing the management of designated sites resulting from the increasingly tangible effects of climate change. In the freshwater environment, the role of designated sites is very much under the spotlight because of the implementation of the European 'Water Framework' Directive, which aspires to holistic, ecologically-based management of aquatic habitats.This paper explores the underlying premises of, and rationale for, special site designations for wildlife, and provides a frank account of the inevitable clash of management philosophies that designated sites create in the freshwater environment, drawing on experiences of managing designated freshwater sites in England over the past decade. A positive role is outlined for designated sites in freshwater conservation, which addresses these management conflicts in a way that not only meets Government obligations towards these sites but also paves the way for enlightened, progressive management of the wider freshwater resource. As part of this account, attempts are made to clarify the relationship between key biodiversity-related policy drivers in the freshwater environment, and to explain how the spectre of climate change can be addressed within designated site management. The importance of strategic freshwater science, collaboratively designed and funded, in maximising the value of the designated freshwater site network to the wider freshwater habitat resource, is stressed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

It has been estimated that in England and Wales fresh water covers some 340 square miles of which about one quarter is inhabited mainly by salmon and trout; in Scotland the lakes cover an area of 340 square miles. The principal object of this publication is to make available in handy form some of the methods, especially those involving the use of manures, by which crops of fish from water can be increased. The cultivation of water which this implies may be compared directly to the cultivation of farm land: the conditions for growth are made as favourable as possible, the seed is sown in the form of young fish, and after one or perhaps two growing seasons the crop is harvested. There are however many waters about the country where marketable fish are already available and can be removed without prejudice to, and indeed to the advantage of, sporting fisheries. In such cases it is necessary only to remove the fish and to rely on the natural processes of reproduction of those which are left to repopulate the water. Farming waters in the true sense is the concern of the greater part of this publication; the removal of crops of otherwise unwanted fish is considered in the last two sections on perch trapping and eel fisheries.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper is designed to give a general account of freshwater biology as it bears on waterworks practice. Most water that is used for consumption will commonly go through a storage reservoir. Here special reference is given to the biological relations in standing waters, the biological control of water supplies, methods of plankton estimation, the biology of slow sand filtration and the use of algicides.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The Workinq Party of North West Water Authority and the Annan District Salmon Fishery Board's aims were to identify the current problems relating to the salmon and freshwater fisheries in the Solway Firth and its tributaries (embracing the catchments of the Annan, Kirtle Water, Sark, Esk, Eden, Wampool and Waver - and possibly also the Lochar Water and the Nith) to produce agreed outline solutions, and to consider the financial aspects of the future administration of these fisheries.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

There is a need to determine quantitative relationships between fishery status and water quality in order to make informed judgements concerning fishery health and the setting of environmental quality standards for fishery protection. Such relationships would also assist in the formulation of a system for classifying fisheries. A national database of fisheries and water quality has been collated from the archives of pollution control authorities throughout the UK. A number of probable and potential water quality effects on fish populations have been identified from a thorough analysis of the database, notwithstanding large confounding effects such as habitat variation and fish mobility, and the generally sparse nature of water quality information. A number of different approaches to data analysis was utilised, and the value of each has been appraised. Recommendations concerning the integration of water quality assessment approaches have been made and further research on fishery status, and its measurement, in relation to water quality has been suggested.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The essential aim of this study was to provide a broad foundation of biological knowledge upon which a programme of mussel utilization and management could be built. Results of the study are presented in three main sections. Part 1 describes the stock of Lake Kariba and Lake McIlwaine; part 2 describes various aspects of the breeding biology of the three species; and part 3 presents the results of morphological, biochemical and age analyses - aspects which are used for initial standing crop and production calculations. The final discussion concludes the thesis with a general examination in ecological terms of the factors which have influenced the development and nature of the mussel faunas of the two lakes under consideration.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Production and consumption of fish were estimated for a one year period during 1995-96 using a sample of 5 117 households. The sample was taken from a study area covering 83 sample communes in 51 fishing districts belonging to eight freshwater fisheries provinces. About 39% of households in fishing dependent communities were actively involved in fishing. Of the total fishing households, 14% took part in commercial fishing using middle-scale fishing gear. Average annual catch per household for middle-scale and family fishing was 3 319 kg and 647 kg, respectively. Nearly 40% of the fish catch was consumed within the communes. The per capita consumption of fresh fish by fishing households (49.7 kg/yr) was higher than that of non-fishing households (39.9 kg/yr). Including processed fish, the total fish consumption by the fishing dependent communes was estimated at 75.6 kg per capita per annum. Given this high rate of fish consumption, development interventions must consider the role of fisheries in ensuring a sustainable livelihood and food security to Cambodia's growing population.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The article highlights the aquaculture of marble or sand goby (Oxyeleotris marmoratus) in Malaysia. Topics discussed are: breeding, hatchery and nursery techiques, nutrition, growout techniques, and diseases.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A discussion is presented on the current problems facing the freshwater fisheries of Sri Lanka, following the decision taken by the Government to abolish the Inland Fisheries Division of the Fisheries Ministry and to stop aid to freshwater fisheries and aquaculture on the grounds that such practices are not in accordance with the history and tradition of the people of Sri Lanka. Without government subsidies, help and regulation, the freshwater fishery and aquaculture sectors are in grave danger of complete collapse. The need for a comprehensive management plan for the multiple use of the country's reservoirs is stressed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Many interconnected problems involved for the conservation of freshwater fish genetic resources of India are enumerated. Some possible solutions to the problems are also discussed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A list of freshwater fishes inhabiting lakes, reservoirs and rivers of Armenia is presented which include 39 species and subspecies belonging to 5 orders, 9 families and 29 genera. A brief description of the ecology, distribution and present status (introductions, threats, commercial value) of these fishes is given.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Freshwater pearl culture is growing as a source of employment and income in many Southeast Asian countries. Bangladesh, Thailand, the Philippines and Vietnam have initiated freshwater pearl culture projects in recent years. In India, the Central Institute of Freshwater Aquaculture is carrying out research on identification of suitable local pearl mussel species (Genera Lamellidens)defining appropriate surgical implantation procedures, developing post-operative care procedures and captive pond culture of mussels.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The management of African freshwater fisheries in Southern African Development Coordination (SADC) countries is discussed. Changes in catch and fishing effort in the SADC freshwater fisheries in the past 50 years, the main causes behind the patterns of change in fishing effort, the effects of fishing effort and environment on the regeneration of fish stocks, as well as existing and proposed fisheries management regulations are investigated.