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CONSERVATION Aim HYDROPOWER MANAGEMENT IN THE PYRENEMi RIVERS (1~-SPAIN)
<br />M. Angeles Puig, Jorge Mato & Marina Aboal*. Centro de 7nvestigaciones del Agua
<br />La Poveda, 28500 Arganda del Rey, Madrid, Spain. *Departrnent of Vegetal Biology
<br />Murcia University, 30100 Murcia, Spain.
<br />The Pyrenean watersheeds of Ebro basin are sti~bmitted to a strong hydropower management. We
<br />can tell different: kinds of gestion: a) little hydropower plants, which affecting to the
<br />river flow a part of year only (spring) and in small stretches; b) the hydropower plants
<br />associated to water transfer from Pyrenean lake catchments, with very increase .flow at
<br />time of thaw; c) the reservoir for hydropower production, this kind induced dry areas
<br />downstrean the reservoir or reduced flay in summer, short-term fluctuations (daily patterns)
<br />The two first kind were building in the up stretches( 1000 m.a.s.l.) ar-d they were the
<br />most commonly in the east section of Pyrenean, mountains. The last kind was distributed on
<br />west Pyrenean.
<br />A long of 1990 we have beginirag the study of conservation state of rivers associated to
<br />hydropower management in the east section of Pyrenean Mountains. The first data apointing
<br />to different conservation status between fish populations, invertebrate and algae communi-
<br />ties. The most important differences appear associate to the biomas of flnctional irrverte-
<br />brate groups.
<br />STRATEGIES FOR CONSERVATION AND MANAGEMENT OF VANISHING GANGETIC DOLPHIN
<br />(Platinista gangettca). Arun K. Singh, Freshwater Biology Laboratory,
<br />B.D.E. College, Patna-800 001, India and S. Hasib Ahmad, Associate Professor
<br />Fisheries, Bihar Veterinary College, Patna-14, India.
<br />The River Ganga is the largest river system of India, its basin covers an area of 0.861
<br />million sq. km. It covers 26x land mass end carries 25x of India's water wealth. This
<br />river harbors the only aquatic mammal, the freshwater dolphin (Platinista gangetica).
<br />Unfortunately the population of this species is gradually declining. The various major
<br />threats to this animal are due to indiscriminate catching of small, young and adult
<br />specimens, poaching, and pollution of the river. Remedial measures may take several
<br />forms, such as complete prohibition by legislation for indiscriminate capture of this
<br />endangered and threatened species. In case they are accidentally caught during fishing
<br />operations, they should be released back into the river as early as possible in living
<br />condition. The pollution of the river by human agencies depositing sewage, sullage,
<br />domestic effluent, chemical detergents, and silting causing death of the animals and
<br />their food organisma sould be completely stopped by enforcing laws. As the stock of
<br />this species is depleted, the seeding of the river with juveniles should be adopted.
<br />Sanctuaries or reserves should be established for protecting this valuable vanishing
<br />freshwater Gangetic dolphin. The other measures of conservation for protecting this
<br />aquatic mammal as well as various management measures to be adopted will be discussed in
<br />detail.
<br />THE REHABILITATION OF A FAST-GROWING BROWN TROUT (SAZ?f0 TRUTTA L.)
<br />POPULATION BY STOCKING. Per Aass, University of Oslo, Zoological Museum,
<br />Sarsgt. 1, N-0562 Oslo 5, Norway.
<br />During the last 70 years, the Norwegian Lake Mjosa end its inflowing rivers have been
<br />subjected to serious changes due to hydroelectric power development. Regulation of the
<br />main inlet river, Gudbrandsdalslagen, started in 1919. The river power station at the
<br />Hunder falls was completed in 1964. The majority of the ascending spawners of the
<br />fast-growing strain of brown trout, SaZmo trutta L. settled below the falls. During its
<br />construction, the water flow below the dam was at times cut off in winter. This caused
<br />the immediate death of a great number of spent spawners. The running of the power plant
<br />led to a severe reduction in the water flow below the dam, and the most important
<br />spawning and nursery areas were, affected. The natural smolt production was permanently
<br />reduced, although to an unknown degree.
<br />The rehabilitation program included the construction of a fish ladder through the dam,
<br />so as to open the river above for spawning, as well as a fixed minimum flow below the
<br />dam. A hatchery was built and a stocking program using the local strain was imposed.
<br />Among the relief measures the effect of stocking has been the easiest to evaluate. The
<br />ascent of wild spawners has stabilized at s low level and hatchery-reared fish
<br />constitute a growing share of the spawning population. During the last 5 years the
<br />total number of spawners controlled in the fish ladder has varied between 151 end 349•
<br />Of these, 46.8x have been stocked. The Lake Mjosa stocked fish constitute about 1/3 of
<br />the total yearly catch, estimated to be 10,000 kg. The effect of smolt size, stocking
<br />time and location on survival is considerable.
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