There are over 1000 different obstacles in Latvian rivers that hinder fish migration, according to data obtained from an inventory of Latvian rivers carried out by the BIOR research institute. Obstacles include not only dams and hydroelectric power plants, but also stone piles, beaver dams and various culverts.
To determine the condition of Latvian rivers, researchers from the BIOR research institute have carried out an inventory, dividing all rivers into one-kilometre fragments and collecting all relevant information about them. As a result, 1549 rivers and streams have been organised into a list of Latvian rivers according to their importance in preserving fish fauna, with a coefficient calculated for each river and stream. In addition, a list of potential significance has been created, which analyses how rich and valuable the rivers could be. (...)