Study the following statements regarding the threats to biodiversity.
I. The existence of many commercially important marine fishes is endangered as they are over harvested.
II. When alien species are introduced into a habitat, they turn invasive and establish themselves at the cost of indigenous species.
III. African cat fish introduced into Lake Victoria, in east Africa led to the extinction of more than 200 species of cichlid fish in the lake.
Identify the correct statements.

The existence of many commercially important marine fishes is endangered as they are over harvested. This exemplifies loss of biodiversity due to overexploitation.
Most of the alien species introduced into a habitat become invasive and establish themselves at the cost of indigenous species. This happens due to lack of their predators and competitors from their native habitat in the new land. Nile perch introduced into Lake Victoria, in east Africa led to the extinction of more than 200 species of cichlid fish in the lake. These two cases exemplify alien species invasion.