Populations of Atlantic bluefin tuna have decreased dramatically due to over fishing. This is an example of illegal fishing.
Step-by-step explanation:
Fishing zones are mainly concentrated on those areas having adequate supply of sun rays in the phoetic zone, abundance of planktons and adequate mixing of cold and warm ocean currents. Each and every ocean has some specific fishing enriched zone where all the said conditions are available.
Likewise in the Atlantic ocean Bluefin fishes are in large number and they are being fished rapidly and decreased dramatically. This is called over fishing and caused due to illegal fishing. In case of forest fell down of trees rapidly and cutting down causes deforestation.