Maintaining corridors and natural habitat fragments
Fragmentation of natural ecosystems is generally seen to be one of the most important threats to biodiversity. Fragmentation occurs when human activities such as agricultural develop-ment, forestry or urbanisation remove large proportions of the natural ecosystem and replace them with a greatly modified matrix, within which small remnants of the native ecosystem remain. Corridors of native vegetation linking fragments are commonly seen as a solution, but the decision to include corridors in a conservation network has to be taken with numerous factors in mind. It is very important for fishes to maintain spawning migration ways in rivers.