At present we lack solid information about the salmon spawning migration in the large northern Swedish rivers, their reproductive success, the size, number and survival of the juveniles, etc. Swedish salmon biologists monitor the juvenile production in the rivers by doing "quantitative" fishing surveys during the summer, in parts of the watershed. Unfortunately, these measurements are not reliable. Most northern salmon rivers currently have a low abundance of juveniles with few individuals per 100 m2. Abundance in the test areas, in the Vindelälven for example, does not correspond to the number of adult salmon returning a few years later to the rivers.

Data on the juvenile production is and will be uncertain if we cannot monitor or calculate the number of salmon offspring on the spawning sites. One reason for this is that fishery biologists by experience choose areas what they "believe" are the spawning areas and this do not always coincide with the real "salmon" world.

In other words, there's lack of detailed knowledge where spawning sites are distributed in large rivers. We aim for having the salmon to choose their own spawning areas and then monitor those areas. Information about this is vital and of basic importance for the long-term management and conservation of wild salmon stocks. Otherwise, there is a great risk that we will lose local salmon stocks.

Data gathered in this study will provide reliable estimates of the production of salmon juveniles in the river, to be used in forthcoming stock-recruitment models to help the threatened wild salmon.