996 resultados para SPECTROSCOPIC INVESTIGATIONS


Relevância:

20.00% 20.00%

Publicador:

Resumo:

All species of fish are able to propagate and maintain their numbers provided that no adverse influence occurs to change the compatible environment, the salmon is no exception. Propagation of fish by artificial means has long been a subject of discussion amongst fishery workers and views have been expressed (both favourable and unfavourable) on the merits of the various methods employed. In an attempt to discover whether artificial propagation was necessary and also to find the best methods of propagation to adopt in the various rivers, a phased programme of investigation into natural spawning efficiency and the results obtained by various methods of artificial propagation was started in the Lancashire River Board area during 1957. The object being to seek information on: (1) The survival of ova from natural spawnings to the eyed and alevin stages. (2) The population density of feeding fry (from natural spawnings) at various intervals of development. (3) The viability of green ova and eyed ova- when planted artificially. (4a) The survival to 0+ parr from implants of eyed ova unfed fry and fed fry. (4b) Populations per unit area of 0+ parr from various planting densities of eyed ova, unfed fry and fed fry. Sampling stations were selected on the Rivers Ribble, Lune and Wyre watersheds for the purpose of marking and examination of natural salmon redds.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This report explores salmon propagation in the Lancashire River Board area (North West of England), looking at the Rivers Lune, Wyre, Ribble, and Hodder, showing salmon catch statistics, methods of propagation and habitat conditions investigations.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Langcliffe hatchery investigations looks at fish mortalities for salmon (fry), sea trout, brown trout and rainbow trout, and explores the River Ribble's water supply.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Galaxies are clusters of millions and billions of stars dynamically stable, with gas, dust and dark matter. They are the biggest isolated objects known in the Universe . Even though they are very complex systems, today we have a clear knowledge about their evolution and about their physical phenomena. Aside from the stellar component there is a gaseous component, principally neutral Hydrogen (HI), and dust that, although is not a significant component in terms of the mass, plays an important role on the absorption phenomena. Finally, cinematic and other kind of observations suggest the existence of a spheric dark matter halo, dominant in terms of mass and more extensive than the barionic component.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This is the Report to the Devon River Board on the investigations in the Walla Brook (1955-58). This report provides information on the nature and quantification of the bottom fauna, the population of fish and their habits and behaviour throughout the year, and the relation of this fish population to the potential stock-carrying capacity of the river. It includes a bottom fauna list with occurring invertebrates and an Addendum to the report.