This subsector comprises establishments primarily engaged in catching fish and other wild animals from their natural habitats. These establishments are dependent upon a continued supply of the natural resource. The catching of fish is the predominant economic activity of this subsector and it usually requires specialized vessels that, by the nature of their size, configuration and equipment, are not suitable for any other type of production, such as transportation. Hunting and trapping utilize a wide variety of production processes and are classified in the same subsector as fishing because the availability of resources and the constraints imposed, such as conservation requirements and proper habitat maintenance, are similar.