In Norway, the number of salmon escaping from fish farms exceeds the wild population, resulting in wild types diminished due to introgression of domestic stocks, loss of genetic adaptation to local conditions as well as potential susceptibility to diseases. It has prohibited siting of salmon farms within 30km of important salmon runs. Marine environment and preservation of the marine biodiversity does not only concern developing countries but more so than ever concerns the industrialised countries which have lost much of theirs. Spectrum of risks posed by GMOs include adverse effects on humans and animals as well as disruption of ecological processes. Currently, there are no effective regulations of control.
Some organisms depend on certain factors to trigger specific biological reactions e.g. spawning.
Then, they move upstream into low-medium salinity reaches. When mature, they move out from the low-medium salinity zones to the estuary and reefs to spawn. In the process, they inhabit and utilise more than 10 different types of critical habitats in succession, in addition to daily diurnal migration between numerous habitat types. The yield is proportionate to the presence of wetlands area. Many cultured organisms cannot be bred in captivity.