Between 1967 and 1972, an African cichlid fish introduced into Gatun Lake in Panama wiped out six of the eight previously common fish species, drastically reduced populations of a seventh, and took a toll up and down the food chain among aquatic invertebrates, algae, and fish-eating birds. The screwworm threatened some 70 million head of livestock in North Africa and could have spread to Sub-Saharan Africa, the Middle east, southern Europe and Asia. Impact of Introduced Species on Gene Pools Even introducing the same species can present hazards through the mixing of genetic stocks. Furthermore, largely homozygous fish under culture in ponds or in cages at sea can reduce the heterozygosity of the same species in the wild should they escape and interbreed. In many cases, introducing new crops or livestock or new varieties can be extremely beneficial.
All countries grow some crops imported from other regions.
Impact on Introduced Species on Society Regulations need to consider the potential social impacts of introductions too. Even where an introduction is judged beneficial, the potential impacts cannot be minimized unless the local communities and institutions are alerted to upcoming releases. Fundamentally, regulations must ensure that no organism can be released without first getting the host country government's consent. Guidelines Nations should strictly regulate the transfer of species and genetic resources and their release into the wild. Introduction of an alien species should be considered only if no native species seems suitable for the same purpose.